Development of dental charts according to tooth development and eruption for Turkish children and young adults

International Nuclear Information System (INIS)

Karadayl, Beytullah; Ozaslan, Abdi; Afsin, Hueseyin; Karadayi, Suekriye

2014-01-01

In this study, we aimed to develop dental charts for Turkish children and young adults of both genders within the age group of 4.5-22.5 years according to tooth mineralization and eruption in a format similar to that proposed by AlQahtani et al. In total, 753 digital panoramic radiographs from 350 males and 403 females were assessed. The permanent teeth were evaluated according to the classification system described by Demirjian et al. The eruption stage was assessed with Bengston's system, which was modified by AlQahtani et al at four points. Teeth generally developed earlier in females than in males. This was particularly notable in the age group of 5-14 years. However, this difference was usually visible in only one stage, not in all teeth. It has been determined that the mixed dentition period ended with the shedding of the second deciduous molars in both genders. The dental charts presented here included information that could be beneficial to dental clinicians in making appropriate diagnosis and planning orthodontic and surgical procedures. These charts also provided datasets for preliminary dental age estimation in Turkish children and young adults.

Development of dental charts according to tooth development and eruption for Turkish children and young adults

Energy Technology Data Exchange (ETDEWEB)

Karadayl, Beytullah; Ozaslan, Abdi [University of Istanbul, Cerrahpasa Faculty of Medicine, Forensic Medicine Department, Istanbul (Turkey); Afsin, Hueseyin [University of Istanbul, Cerrahpasa Faculty of Medicine, Forensic Medicine Department, Istanbul (Turkey); Karadayi, Suekriye [Public Health Agency, Istanbul (Turkey)

2014-06-15

In this study, we aimed to develop dental charts for Turkish children and young adults of both genders within the age group of 4.5-22.5 years according to tooth mineralization and eruption in a format similar to that proposed by AlQahtani et al. In total, 753 digital panoramic radiographs from 350 males and 403 females were assessed. The permanent teeth were evaluated according to the classification system described by Demirjian et al. The eruption stage was assessed with Bengston's system, which was modified by AlQahtani et al at four points. Teeth generally developed earlier in females than in males. This was particularly notable in the age group of 5-14 years. However, this difference was usually visible in only one stage, not in all teeth. It has been determined that the mixed dentition period ended with the shedding of the second deciduous molars in both genders. The dental charts presented here included information that could be beneficial to dental clinicians in making appropriate diagnosis and planning orthodontic and surgical procedures. These charts also provided datasets for preliminary dental age estimation in Turkish children and young adults.

Correlation between permanent tooth eruption pattern and the predominance of the motor function laterality.

Science.gov (United States)

Veloso-Durán, Ana; Vazquez-Salceda, Ma Carmen; López-Jiménez, Julian; Veloso-Durán, Margarita; Puigdollers, Andreu

2014-09-01

To asses whether dental eruption order can play a role in the early diagnosis of crossed laterality. Dental eruption pattern along with eye, ear, hand and foot lateralism were examined on 131 children between 6 to 8 years old from public schools from a multietnic population area of Barcelona city. Statistic methods (Statgraphics Plus 5.1 program) were used to evaluate data recollected. Only foot and dentition lateralities behave as independent variables regarding hand laterality. So dental eruption laterality (along with the foot one) would be one of the parameters more related to hand laterality given that dentition variable relationship is greater that the foot one. This suggests that tooth eruption could be more clinically relevant. Crossed laterality hand-foot is significantly more predominant in men (13%) than in women (1,6%). Meanwhile, the relationship between hand and dentition didn't show any influence of sex. Dental eruption order, can be used as a good parameter in the determination of the patient's laterality.

Characterization of glycosaminoglycans during tooth development and mineralization in the axolotl, Ambystoma mexicanum.

Science.gov (United States)

Wistuba, J; Völker, W; Ehmcke, J; Clemen, G

2003-10-01

Glycosaminoglycans (GAGs) involved in the formation of the teeth of Ambystoma mexicanum were located and characterized with the cuprolinic blue (CB) staining method and transmission electron microscopy (TEM). Glycosaminoglycan-cuprolinic blue precipitates (GAGCB) were found in different compartments of the mineralizing tissue. Various populations of elongated GAGCB could be discriminated both according to their size and their preferential distribution in the extracellular matrix (ECM). GAGCB populations that differ in their composition could be attributed not only to the compartments of the ECM but also to different zones and to different tooth types (early-larval and transformed). Larger precipitates were only observed within the dentine matrix of the shaft of the early-larval tooth. The composition of the populations differed significantly between the regions of the transformed tooth: pedicel, shaft and dividing zone. In later stages of tooth formation, small-sized GAGCBs were seen as intracellular deposits in the ameloblasts. It is concluded that the composition of GAGCB populations seems to play a role in the mineralization processes during tooth development in A. mexicanum and influence qualitative characteristics of the mineral in different tooth types and zones, and it is suggested that GAGs might be resorbed by the enamel epithelium during the late phase of enamel formation.

Effect of early childhood malnutrition on tooth eruption in Haitian adolescents.

Science.gov (United States)

Psoter, W; Gebrian, B; Prophete, S; Reid, B; Katz, R

2008-04-01

The objective of this retrospective cohort study was to determine the effects of early childhood protein-energy malnutrition (EC-PEM) and current nutritional status as defined by anthropomorphic measures on the exfoliation and eruption patterns of teeth among adolescents. Oral clinical examinations were conducted in 2005 using World Health Organization (WHO) diagnostic criteria on 498 11- to 13-year-old Haitians for whom early childhood malnutrition data were available. Anthropomorphic records (weight-for-age) from the Haitian Health Foundation computerized database on children from birth through 5-years old were utilized. Current heights and weights were ascertained. Both sets of data were converted to z-scores based on the National Center for Health Statistics (NCHS) referent database. Based upon these z-scores, EC-PEM and current malnutrition categories were developed for this study. The analyses separately regressed the number of primary and permanent teeth on age, gender, EC-PEM status and current nutritional status. Both a delayed exfoliation of primary teeth and a delayed eruption of permanent teeth were associated with EC-PEM and current stunting in adolescence. The observed associations were either direct and statistically significant or indirectly demonstrated by presenting evidence of confounding. The overall interpretation of the models is that malnutrition beginning in the earliest years and extending throughout childhood influences the exfoliation and eruption of teeth. These findings present evidence of an association between tooth exfoliation/eruption patterns and both EC-PEM and nutritional insufficiency (stunting) throughout childhood. This observed delay in the exfoliation of the primary dentition and in the eruption of the permanent dentition has practical significance in interpreting age-specific dental caries data from populations with different malnutrition experiences.

Identification of six novel PTH1R mutations in families with a history of primary failure of tooth eruption.

Science.gov (United States)

Risom, Lotte; Christoffersen, Line; Daugaard-Jensen, Jette; Hove, Hanne Dahlgaard; Andersen, Henriette Skovgaard; Andresen, Brage Storstein; Kreiborg, Sven; Duno, Morten

2013-01-01

Primary Failure of tooth Eruption (PFE) is a non-syndromic disorder which can be caused by mutations in the parathyroid hormone receptor 1 gene (PTH1R). Traditionally, the disorder has been identified clinically based on post-emergent failure of eruption of permanent molars. However, patients with PTH1R mutations will not benefit from surgical and/or orthodontic treatment and it is therefore clinically important to establish whether a given failure of tooth eruption is caused by a PTH1R defect or not. We analyzed the PTH1R gene in six patients clinically diagnosed with PFE, all of which had undergone surgical and/or orthodontic interventions, and identified novel PTH1R mutations in all. Four of the six mutations were predicted to abolish correct mRNA maturation either through introduction of premature stop codons (c.947C>A and c.1082G>A), or by altering correct mRNA splicing (c.544-26_544-23del and c.989G>T). The latter was validated by transfection of minigenes. The six novel mutations expand the mutation spectrum for PFE from eight to 14 pathogenic mutations. Loss-of-function mutations in PTH1R are also associated with recessively inherited Blomstrand chondrodysplasia. We compiled all published PTH1R mutations and identified a mutational overlap between Blomstrand chondrodysplasia and PFE. The results suggest that a genetic approach to preclinical diagnosis will have important implication for surgical and orthodontic treatment of patients with failure of tooth eruption.

Identification of six novel PTH1R mutations in families with a history of primary failure of tooth eruption.

Directory of Open Access Journals (Sweden)

Lotte Risom

Full Text Available Primary Failure of tooth Eruption (PFE is a non-syndromic disorder which can be caused by mutations in the parathyroid hormone receptor 1 gene (PTH1R. Traditionally, the disorder has been identified clinically based on post-emergent failure of eruption of permanent molars. However, patients with PTH1R mutations will not benefit from surgical and/or orthodontic treatment and it is therefore clinically important to establish whether a given failure of tooth eruption is caused by a PTH1R defect or not. We analyzed the PTH1R gene in six patients clinically diagnosed with PFE, all of which had undergone surgical and/or orthodontic interventions, and identified novel PTH1R mutations in all. Four of the six mutations were predicted to abolish correct mRNA maturation either through introduction of premature stop codons (c.947C>A and c.1082G>A, or by altering correct mRNA splicing (c.544-26_544-23del and c.989G>T. The latter was validated by transfection of minigenes. The six novel mutations expand the mutation spectrum for PFE from eight to 14 pathogenic mutations. Loss-of-function mutations in PTH1R are also associated with recessively inherited Blomstrand chondrodysplasia. We compiled all published PTH1R mutations and identified a mutational overlap between Blomstrand chondrodysplasia and PFE. The results suggest that a genetic approach to preclinical diagnosis will have important implication for surgical and orthodontic treatment of patients with failure of tooth eruption.

Orientation and deformation of mineral crystals in tooth surfaces.

Science.gov (United States)

Fujisaki, Kazuhiro; Todoh, Masahiro; Niida, Atsushi; Shibuya, Ryota; Kitami, Shunsuke; Tadano, Shigeru

2012-06-01

Tooth enamel is the hardest material in the human body, and it is mainly composed of hydroxyapatite (HAp)-like mineral particles. As HAp has a hexagonal crystal structure, X-ray diffraction methods can be used to analyze the crystal structure of HAp in teeth. Here, the X-ray diffraction method was applied to the surface of tooth enamel to measure the orientation and strain of the HAp crystals. The c-axis of the hexagonal crystal structure of HAp was oriented to the surface perpendicular to the tooth enamel covering the tooth surface. Thus, the strain of HAp at the surface of teeth was measured by X-ray diffraction from the (004) lattice planes aligned along the c-axis. The X-ray strain measurements were conducted on tooth specimens with intact surfaces under loading. Highly accurate strain measurements of the surface of tooth specimens were performed by precise positioning of the X-ray irradiation area during loading. The strains of the (004) lattice plane were measured at several positions on the surface of the specimens under compression along the tooth axis. The strains were obtained as tensile strains at the labial side of incisor tooth specimens. In posterior teeth, the strains were different at different measurement positions, varying from tensile to compressive types. Copyright © 2012 Elsevier Ltd. All rights reserved.

Inactivation of IL11 signaling causes craniosynostosis, delayed tooth eruption, and supernumerary teeth

DEFF Research Database (Denmark)

Nieminen, Pekka; Morgan, Neil V; Fenwick, Aimée L

2011-01-01

Craniosynostosis and supernumerary teeth most often occur as isolated developmental anomalies, but they are also separately manifested in several malformation syndromes. Here, we describe a human syndrome featuring craniosynostosis, maxillary hypoplasia, delayed tooth eruption, and supernumerary...... teeth. We performed homozygosity mapping in three unrelated consanguineous Pakistani families and localized the syndrome to a region in chromosome 9. Mutational analysis of candidate genes in the region revealed that all affected children harbored homozygous missense mutations (c.662C>G [p.Pro221Arg], c...... for the treatment of craniosynostosis....

Disturbances in Tooth Mineralization and Forensic Dental Age Estimations

DEFF Research Database (Denmark)

Jensen, Niels Dyrgaard; Arge, Sára Oladóttir; Larsen, Sara Tangmose

When performing a forensic dental age assessment, mineralization disturbances of the teeth and the possible consequences these may have upon the reliability of the assessment must be taken into consideration. Furthermore, mineralization disturbances of a general character in the teeth may be seen...... as an indicator of more systemic insults during tooth formation and thus supplement the examination performed by the forensic pathologist. At our department the forensic dental age assessment is based upon a dental panoramic image, intra oral images of the third molars as well as a clinical photograph...

Localization of Heat Shock Protein 27 (Hsp27) in the Rat Gingiva and its Changes with Tooth Eruption

International Nuclear Information System (INIS)

Sasaki, Au; Yamada, Tohru; Inoue, Katsuyuki; Momoi, Tomoko; Tokunaga, Hiroshi; Sakiyama, Koji; Kanegae, Haruhide; Suda, Naoto; Amano, Osamu

2011-01-01

Heat shock protein 27 kDa (Hsp27) functions as a molecular chaperon to prevent apoptosis as well as to contribute to the regulation of cell proliferation and differentiation during development. In the present study, the localization of Hsp27 in the oral epithelium of rats and its expression change during formation of the gingiva with the tooth eruption were examined immunohistochemically to elucidate the roles of Hsp27 in the oral mucosa. In adult rats, Hsp27-immunoreactivity was localized in the prickle and granular layers but absent in the basal and horny layers of the oral epithelium. On the other hand, in the outer and sulcular epithelia of the free gingival, Hsp27-immunoreactivity was detected in the whole layers, while it was not found in the proliferation zone of the junctional epithelium immunoreactive for Ki67. In immature rats on 10th postnatal day, Hsp27-immunoreactivity was intense in the prickle and granular layers of the oral epithelium, but was not detected in its basal layer. In rats at the eruptive phase on 15th postnatal day, Hsp27-immunoreactivity was detected in sites of the basal layer adjacent to where the dental cusps penetrated through the oral epithelium. Although the immunoreactivity for Ki67 was found in the basal layer of the oral epithelium, it was not localized in the Hsp27-immunopositive sites of tooth-penetration in the basal layer. Just after the tooth-eruption on 20th postnatal day, Hsp27-immunoreactivity was not found in the stratified squamous epithelium at the dentogingival junction, whereas it was intense in a single layer of cuboidal epithelial cells attached to the tooth neck. Ki67-positive cells were scattered in the stratified squamous epithelium at the dentogingival junction, whereas no positive cells were found in the portion of a single layer of cuboidal epithelial cells. These findings suggest that the outer and sulcular epithelia of the free gingiva have a relatively slower rate of proliferation than other gingival and

Premature eruption of the premolars.

Science.gov (United States)

Camm, J H; Schuler, J L

1990-01-01

This paper presents a variety of cases in which very early loss of abscessed primary molars caused early eruption of the permanent successors. Clinical sequelae including ectopic eruption, alteration of eruption sequence, arch-length inadequacy and tooth impaction are illustrated by five case reports.

Sea urchin tooth mineralization: Calcite present early in the aboral plumula

Science.gov (United States)

Stock, Stuart R.; Veis, Arthur; Xiao, Xianghui; Almer, Jonathan D.; Dorvee, Jason R.

2012-01-01

In both vertebrate bone, containing carbonated hydroxyapatite as the mineral phase, and in invertebrate hard tissue comprised of calcium carbonate, a popular view is that the mineral phase develops from a long-lived amorphous precursor which later transforms into crystal form. Important questions linked to this popular view are: When and where is the crystallized material formed, and is amorphous solid added subsequently to the crystalline substrate? Sea urchin teeth, in which the earliest mineral forms within isolated compartments, in a time and position dependent manner, allow direct investigation of the timing of crystallization of the calcite primary plates. Living teeth of the sea urchin Lytechinus variegatus, in their native coelomic fluid, were examined by high-energy synchrotron x-ray diffraction. The diffraction data show that calcite is present in the most aboral portions of the plumula, representing the very earliest stages of mineralization, and that this calcite has the same crystal orientation as in the more mature adoral portions of the same tooth. Raman spectroscopy of the aboral plumula confirms the initial primary plate mineral material is calcite and does not detect amorphous calcium carbonate; in the more mature adoral incisal flange, it does detect a broader calcite peak, consistent with two or more magnesium compositions. We hypothesize that some portion of each syncytial membrane in the plumula provides the information for nucleation of identically oriented calcite crystals that subsequently develop to form the complex geometry of the single crystal sea urchin tooth. PMID:22940703

Requirement of alveolar bone formation for eruption of rat molars

Science.gov (United States)

Wise, Gary E.; He, Hongzhi; Gutierrez, Dina L.; Ring, Sherry; Yao, Shaomian

2011-01-01

Tooth eruption is a localized event that requires a dental follicle (DF) to regulate the resorption of alveolar bone to form an eruption pathway. During the intra-osseous phase of eruption, the tooth moves through this pathway. The mechanism or motive force that propels the tooth through this pathway is controversial but many studies have shown that alveolar bone growth at the base of the crypt occurs during eruption. To determine if this bone growth (osteogenesis) was causal, experiments were designed in which the expression of an osteogenic gene in the DF, bone morphogenetic protein-6 (BMP6), was inhibited by injection of the 1st mandibular molar of the rat with an siRNA targeted against BMP6. The injection was followed by electroporation to promote uptake of the siRNA. In 45 first molars injected, eruption either was delayed or completely inhibited (7 molars). In the impacted molars, an eruption pathway formed but bone growth at the base of the crypt was greatly reduced as compared to the erupted first molar controls. These studies show that alveolar bone growth at the base of the crypt is required for tooth eruption and that BMP6 may be an essential gene for promoting this growth. PMID:21896048

A systematic review of the consequences of premature birth on palatal morphology, dental occlusion, tooth-crown dimensions, and tooth maturity and eruption.

Science.gov (United States)

Paulsson, Liselotte; Bondemark, Lars; Söderfeldt, Björn

2004-04-01

This systematic review addresses the question whether prematurity results in alteration of palatal morphology, dental occlusion, tooth-crown dimensions, and tooth maturation. A literature survey from the PubMed database covering the period from January 1966 to November 2002 used the Medical Subject Headings terms "infant, premature," and "infant, low birth weight" in combination with "jaws," "dental physiology," "dentition," and "tooth abnormalities." Controlled studies written in English and with definitions of premature birth according to the World Health Organization were selected. Two reviewers selected and extracted the data independently and also assessed the quality of the studies. The search strategy resulted in 113 articles, of which 13 met the inclusion criteria. Scientific evidence was found for altered palatal morphology in the short term among the premature children, and oral intubation was a contributing factor to the alterations. If corrected age was considered for the premature children, no delay in dental development and eruption was found compared with normally born children. Thus, the early birth of premature children must be taken in account when planning for orthodontic treatment. Because of the contradictory results and lack of longitudinal studies, the scientific evidence was too weak to answer the questions whether premature birth causes permanent alteration of palatal morphology, alteration of dental occlusion, and altered tooth-crown dimensions. To answer these questions and obtain reliable scientific evidence whether premature children are at risk for malocclusions from possible alterations of palatal morphology such as asymmetry and high arched palates, further well-designed controlled studies as well as longitudinal studies are needed.

Sea urchin tooth mineralization: calcite present early in the aboral plumula.

Science.gov (United States)

Stock, Stuart R; Veis, Arthur; Xiao, Xianghui; Almer, Jonathan D; Dorvee, Jason R

2012-11-01

In both vertebrate bone, containing carbonated hydroxyapatite as the mineral phase, and in invertebrate hard tissue comprised of calcium carbonate, a popular view is that the mineral phase develops from a long-lived amorphous precursor which later transforms into crystal form. Important questions linked to this popular view are: when and where is the crystallized material formed, and is amorphous solid added subsequently to the crystalline substrate? Sea urchin teeth, in which the earliest mineral forms within isolated compartments, in a time and position dependent manner, allow direct investigation of the timing of crystallization of the calcite primary plates. Living teeth of the sea urchin Lytechinus variegatus, in their native coelomic fluid, were examined by high-energy synchrotron X-ray diffraction. The diffraction data show that calcite is present in the most aboral portions of the plumula, representing the very earliest stages of mineralization, and that this calcite has the same crystal orientation as in the more mature adoral portions of the same tooth. Raman spectroscopy of the aboral plumula confirms the initial primary plate mineral material is calcite and does not detect amorphous calcium carbonate; in the more mature adoral incisal flange, it does detect a broader calcite peak, consistent with two or more magnesium compositions. We hypothesize that some portion of each syncytial membrane in the plumula provides the information for nucleation of identically oriented calcite crystals that subsequently develop to form the complex geometry of the single crystal sea urchin tooth. Copyright © 2012 Elsevier Inc. All rights reserved.

Inherited retarded eruption in the permanent dentition.

Science.gov (United States)

Rasmussen, P; Kotsaki, A

1997-01-01

The term retarded eruption, may be used in cases where eruption is inhibited, causing an interruption in the coordination of tooth formation and tooth eruption. The phenomenon may be local or general, and several etiological factors for retarded eruption have been listed, comprising a lack of space, ankylosis, cysts, supernumerary teeth, hormone and vitamin deficiencies and several developmental disturbances and syndromes. The present paper describes several cases of retarded eruption where no factors other than inheritance have been evident. So far 14 cases have been evaluated, 9 boys and 5 girls. In addition several cases have been registered among parents and grandparents of the probands. Typical features are: retarded eruption, defined as more than 3 SD beyond mean eruption figures, comprises all teeth in the permanent dentition, and in 5 cases also second primary molars. The chronology of tooth formation are within normal limits. Consequently the teeth finish development still laying deeply buried in the jaws, often in aberrant positions and with curves or hooks on the roots. When the teeth finally get the "signal" for eruption, 5-15 years beyond normal eruption time, they move rather quickly into right positions, despite the long eruption paths and the hooked roots. Permanent teeth without, as well as with predecessors, are affected. Extraction of predecessors does not seem to provoke eruption. The main features in management are to take care of the primary teeth, to improve-esthetics, and offer surgery and orthodontics when needed. Analyses of pedigrees indicates that the genetic transmittance may be autosomal dominant as both sexes are affected, about half of the siblings show the trait, and the trait shows continuity through generations.

Spontaneous Eruption of Premolar Associated with a Dentigerous Cyst

Directory of Open Access Journals (Sweden)

Irla Karlinne Ferreira de Carvalho

2016-01-01

Full Text Available Dentigerous cyst (DC is the second most common odontogenic cyst with greater incidence in young patients. It presents as a unilocular, asymptomatic radiolucency involving the crown of an impacted tooth, commonly noticed in X-rays to investigate absence, wrong tooth position, or delay in the chronology of eruption. Decompression/marsupialization (D/M is the most implemented treatment, especially when preserving the tooth involved is advised. The aim of this study is to discuss the DC characteristics that contribute to spontaneous eruption of premolars, by reporting the case of a conservative treatment of DC. This eruption depends on factors such as age, angulation of inclusion, rate of root formation, depth of inclusion, and eruption space. This paper reports the case of a 10-year-old patient with a radiolucent lesion diagnosed as DC involving element 35, which erupted as a result of treatment. The patient was observed during 1 year and 6 months.

Spontaneous Eruption of Premolar Associated with a Dentigerous Cyst.

Science.gov (United States)

de Carvalho, Irla Karlinne Ferreira; Luna, Anibal Henrique Barbosa

2016-01-01

Dentigerous cyst (DC) is the second most common odontogenic cyst with greater incidence in young patients. It presents as a unilocular, asymptomatic radiolucency involving the crown of an impacted tooth, commonly noticed in X-rays to investigate absence, wrong tooth position, or delay in the chronology of eruption. Decompression/marsupialization (D/M) is the most implemented treatment, especially when preserving the tooth involved is advised. The aim of this study is to discuss the DC characteristics that contribute to spontaneous eruption of premolars, by reporting the case of a conservative treatment of DC. This eruption depends on factors such as age, angulation of inclusion, rate of root formation, depth of inclusion, and eruption space. This paper reports the case of a 10-year-old patient with a radiolucent lesion diagnosed as DC involving element 35, which erupted as a result of treatment. The patient was observed during 1 year and 6 months.

Bioactive Polymeric Composites for Tooth Mineral Regeneration: Physicochemical and Cellular Aspects

Science.gov (United States)

Skrtic, Drago; Antonucci, Joseph M.

2011-01-01

Our studies of amorphous calcium phosphate (ACP)-based dental materials are focused on the design of bioactive, non-degradable, biocompatible, polymeric composites derived from acrylic monomer systems and ACP by photochemical or chemically activated polymerization. Their intended uses include remineralizing bases/liners, orthodontic adhesives and/or endodontic sealers. The bioactivity of these materials originates from the propensity of ACP, once exposed to oral fluids, to release Ca and PO4 ions (building blocks of tooth and bone mineral) in a sustained manner while spontaneously converting to thermodynamically stable apatite. As a result of ACP's bioactivity, local Ca- and PO4-enriched environments are created with supersaturation conditions favorable for the regeneration of tooth mineral lost to decay or wear. Besides its applicative purpose, our research also seeks to expand the fundamental knowledge base of structure-composition-property relationships existing in these complex systems and identify the mechanisms that govern filler/polymer and composite/tooth interfacial phenomena. In addition to an extensive physicochemical evaluation, we also assess the leachability of the unreacted monomers and in vitro cellular responses to these types of dental materials. The systematic physicochemical and cellular assessments presented in this study typically provide model materials suitable for further animal and/or clinical testing. In addition to their potential dental clinical value, these studies suggest the future development of calcium phosphate-based biomaterials based on composite materials derived from biodegradable polymers and ACP, and designed primarily for general bone tissue regeneration. PMID:22102967

Longitudinal eruptive and posteruptive tooth movements, studied on oblique and lateral cephalograms with implants.

Science.gov (United States)

Zhang, Xiaoyun; Baumrind, Sheldon; Chen, Gui; Chen, Huizhong; Liang, Yi; Xu, Tianmin

2018-05-01

The purpose of this study was to investigate the eruptive and posteruptive tooth displacements of untreated growing subjects longitudinally and the potential connections between posteruptive displacement of the maxillary and mandibular first molars and skeletal facial growth. The sample comprised 11 series of right 45° oblique cephalograms and lateral cephalograms of untreated children with metallic implants of the Björk type obtained from the archives of a growth study. Cephalograms generated at approximately 2-year intervals between the ages of 8.5 and 16 years were selected and traced. Superimpositions of serial tracings of oblique cephalograms on stable intraosseous implants were made to determine the displacements of buccal segment teeth in both arches, and superimpositions of serial tracings of lateral cephalograms were used to evaluate growth of the jaws. Continuous mesial tipping of the maxillary molars was observed from 8.5 to 16 years of age, averaging 8.2° ± 5.5° for the first molars and 18.3°± 8.5° for the second molars. Compared with the maxillary molars, the mandibular first molars showed less change in angulation except in the later mixed dentition when more than half of the subjects had accelerated forward tipping of the first molar in the late mixed dentition associated with migration into the leeway space. Average amounts of cumulative eruption from 8.5 to 16 years of age were 12.1 ± 2.1 mm downward and 3.8 ± 1.7 mm forward for the maxillary first molar. The mandibular first molar showed 8.6 ± 2.3 mm of eruption and 4.4 ± 1.9 mm of mesial migration. Peak velocity of vertical eruption of the maxillary and mandibular first molars corresponded to the skeletal vertical growth spurt. The maxillary canines and first premolars showed remarkable and continuous uprighting migration during eruption, averaging 9.5° ± 5.0° and 10.5° ± 6.7°, respectively. However, when they erupted into the occlusion, their changes in

Success Rate of Formocresol Pulpotomy versus Mineral Trioxide Aggregate in Human Primary Molar Tooth

Directory of Open Access Journals (Sweden)

S E Jabbarifar

2004-12-01

Full Text Available Background: In spite of long time and broad use of formaldehyde derivates (Fixation agent in primary tooth pulp treatment, There is some concerns about these derivates such as variability, inconsistency success rate, mutagenicity, cytotoxicity, alergenicity, and some other potential health hazards of them. Therefore other alternative pulpotomy procedures like Bioactive glass (BAG, Glutaraldehyde (2%, Hydroxyappetite (HA, Bone dried freezed (BDF, ferric sulfate (15%, laser, Electrosurgery (ES, Bone Morphogenic proteins (BMP, recombinant protein-1 (RP1, and Mineral Trioxide Aggregate (MTA have been compared. The purpose of this clinical trial is to assess radiographic and clinical success rate of Formocresol (FC pulpotomy in compare with MTA in human primary molar teeth. Methods: 64 molars were pulpotomized equally and randomly with mineral trioxide Aggregate and Formocresol. Prior to trial, we defined a case as failure, when one or more of the events such as external root resorption, internal root resorption, periapical and furca lucency, pain, swelling, mobility, dental abscess, or early extraction appeared. Every treated tooth was defined as successful, if any noted evident was not shown. Results: Totally, 60 teeth treatment (92.2 percent were successful and 7.8 percent were failed. Failure and success rates for MTA group were 6.3 and 93.7 percent, respectively. Failure and success rates in FC group were 8.4 and 90.2 percent respectively. The difference between MTA and FC treatment methods was not significant (Fisher Exact test. Conclusion: Findings of this study show that mineral trioxide aggregate can be an alternative procedure for FC pulpotomy of primary tooth. Keywords: Mineral trioxide aggregate, formocresol, pulpotomy, success and failure rate.

Guided tooth eruption: Comparison of open and closed eruption techniques in labially impacted maxillary canines

Directory of Open Access Journals (Sweden)

S M londhe

2014-01-01

Full Text Available Background: After third molars, the maxillary canines are the most commonly impacted permanent teeth and one-third of these are labial impactions. Impacted canines often require orthodontic guidance in the eruption. This study was conducted to assess the posttreatment results of surgically exposed and orthodontically aligned labially impacted maxillary canines comparing two different surgical techniques. Materials and Methods: The study was conducted in two phases, a surgical phase and an orthodontic phase. In surgical phase, events during surgical exposure and recovery of 31 patients with labially impacted maxillary canine were recorded. Patients were managed with open and closed eruption technique. The assessment included comparison of two techniques of surgical exposure, postoperative pain, mobility, vitality, periodontal health, level of impaction, and duration of orthodontic treatment. Results: The postoperative recovery was longer after open eruption than close eruption technique (P = 0.000. Postoperative pain experienced by patients was similar, but regression of pain was faster in closed eruption technique. The mean surgical time for open eruption technique was lesser when compared with closed eruption technique (P = 0.000. The total duration of orthodontic treatment was directly dependent upon the level of impaction, with deeper level of impaction having longer duration of orthodontic treatment. The mobility and vitality of guided canine was similar in both techniques. Conclusion: The closed eruption technique was a longer surgical procedure, but the postoperative pain regression was faster. The duration of orthodontic treatment was longer with deeper level of impaction. The closed eruption surgical techniques provide better periodontal tissues around the guided erupted teeth.

Ectopic eruption of maxillary central incisor through abnormally thickened labial frenum: An unusual presentation

Directory of Open Access Journals (Sweden)

Neeraj Gugnani

2017-01-01

Full Text Available Ectopic eruption is a deviation from the normal eruption pattern, making the tooth erupt out of its normal position, and possibly causing resorption of adjacent primary teeth. A wide range of etiological factors may be responsible for ectopic eruption of the teeth, so their management depends on the correction of the established etiological factor. The present case report describes an unusual case of ectopically erupted central incisor encased within an abnormally thickened labial frenum, which was treated by orthodontic repositioning of the ectopically erupting tooth after frenectomy.

Chronological gene expression of parathyroid hormone-related protein (PTHrP) in the stellate reticulum of the rat: implications for tooth eruption.

Science.gov (United States)

Yao, Shaomian; Pan, Fenghui; Wise, Gary E

2007-03-01

Tooth eruption is a localized event that requires the expression of certain molecules at precise times to regulate bone resorption and bone formation. Parathyroid hormone-related protein (PTHrP) may be one of those molecules. Although PTHrP is produced in the stellate reticulum (SR) of the tooth and exerts its effect on the adjacent dental follicle, its expression pattern in the SR is unknown. Thus, it was the objectives of this study to determine the chronology of expression of PTHrP, and then to determine its effect on vascular endothelial growth factor (VEGF) expression for osteoclastogenesis and on bone morphogenetic protein-2 (BMP-2) for bone growth. Laser capture microdissection and RT-PCR were used to determine the chronological expression of PTHrP in vivo. In vitro, dental follicle cells were incubated with PTHrP and RT-PCR was conducted to determine its effect on VEGF and BMP-2 gene expression. PTHrP was maximally expressed at day 7 postnatally in the SR with the level of expression still high at day 9. In vitro, PTHrP upregulated VEGF120 and VEGF164 expression after 4h of incubation with a maximum effect at 6h. PTHrP upregulated BMP-2 gene expression with a maximal effect at 2h. Because the secondary burst of osteoclastogenesis needed for eruption occurs around day 10, it is possible that PTHrP is stimulating this osteoclastogenesis by upregulating VEGF. Concurrently, the upregulation of BMP-2 by PTHrP may stimulate bone growth at the base of the bony crypt to promote eruption.

An Unusual Case Report of Erupted Odontoma

Directory of Open Access Journals (Sweden)

Dhaval Mehta

2013-01-01

Full Text Available Odontomas are the most common of the odontogenic tumors of the jaws, which are benign, slow growing, and nonaggressive. They are usually asymptomatic and found in routine dental radiographic examination. Odontomas are usually associated with tooth eruption disturbances. Eruption of odontoma in oral cavity is rare entity. Here we report a case of an unusual erupted compound odontoma.

Recent advances in engineering of tooth and tooth structures using postnatal dental cells

Directory of Open Access Journals (Sweden)

Masaki J. Honda

2010-02-01

This review focuses on the performance of postnatal and adult dental cells that have been used for generating teeth. Their ability to contribute to tooth development was assessed in the omentum or in the tooth socket. Adult dental cells were limited in their potential owing to various parameters. From these results described, new approaches for regenerated teeth are proposed in this review. One strategy to replace teeth is tooth root engineering using tissue from postnatal teeth. Since the enamel organ epithelium disappears after tooth maturation, the epithelial rest cells of Malassez were evaluated to determine their capacity to generate enamel. From these results, it is suggested that erupted mature teeth have cell sources with the capacity to produce tooth root. The development of biological approaches for tooth root regeneration using postnatal dental cells is promising and remains one of the greatest challenges in the dental field in the years to come.

Aspects and clinical procedures of eruptive changes of permanent upper canines

Directory of Open Access Journals (Sweden)

Sheila Marcia Francisco

2012-04-01

Full Text Available INTRODUCTION: Even though the upper canine is the tooth that presents most eruption anomalies, after the third molars, canine retention prevalence in the population is quite low. Local, physiologic and pathologic factors can provide difficulties for the tooth eruptive process. The correct diagnosis in trying to prevent upper canine retention with ectopic eruption is fundamental to choose the ideal treatment, which can be performed by various methods. OBJECTIVE: The present paper has the purpose of approaching aspects related to impacted upper permanent canines by a literature review, including localization and treatment conducts.

Identification of Six Novel PTH1R Mutations in Families with a History of Primary Failure of Tooth Eruption

DEFF Research Database (Denmark)

Risom, Lotte; Christoffersen, Line Borck; Daugaard-Jensen, Jette

2013-01-01

Primary Failure of tooth Eruption (PFE) is a non-syndromic disorder which can be caused by mutations in the parathyroid hormone receptor 1 gene (PTH1R). Traditionally, the disorder has been identified clinically based on post-emergent failure of eruption of permanent molars. However, patients...... undergone surgical and/or orthodontic interventions, and identified novel PTH1R mutations in all. Four of the six mutations were predicted to abolish correct mRNA maturation either through introduction of premature stop codons (c.947C>A and c.1082G>A), or by altering correct mRNA splicing (c.544......-26_544-23del and c.989G>T). The latter was validated by transfection of minigenes. The six novel mutations expand the mutation spectrum for PFE from eight to 14 pathogenic mutations. Loss-of-function mutations in PTH1R are also associated with recessively inherited Blomstrand chondrodysplasia. We compiled all...

Dental maturation, eruption, and gingival emergence in the upper jaw of newborn primates.

Science.gov (United States)

Smith, Timothy D; Muchlinski, Magdalena N; Jankord, Kathryn D; Progar, Abbigal J; Bonar, Christopher J; Evans, Sian; Williams, Lawrence; Vinyard, Christopher J; Deleon, Valerie B

2015-12-01

In this report we provide data on dental eruption and tooth germ maturation at birth in a large sample constituting the broadest array of non-human primates studied to date. Over 100 perinatal primates, obtained from natural captive deaths, were screened for characteristics indicating premature birth, and were subsequently studied using a combination of histology and micro-CT. Results reveal one probable unifying characteristic of living primates: relatively advanced maturation of deciduous teeth and M1 at birth. Beyond this, there is great diversity in the status of tooth eruption and maturation (dental stage) in the newborn primate. Contrasting strategies in producing a masticatory battery are already apparent at birth in strepsirrhines and anthropoids. Results show that dental maturation and eruption schedules are potentially independently co-opted as different strategies for attaining feeding independence. The most common strategy in strepsirrhines is accelerating eruption and the maturation of the permanent dentition, including replacement teeth. Anthropoids, with only few exceptions, accelerate mineralization of the deciduous teeth, while delaying development of all permanent teeth except M1. These results also show that no living primate resembles the altricial tree shrew (Tupaia) in dental development. Our preliminary observations suggest that ecological explanations, such as diet, provide an explanation for certain morphological variations at birth. These results confirm previous work on perinatal indriids indicating that these and other primates telegraph their feeding adaptations well before masticatory anatomy is functional. Quantitative analyses are required to decipher specific dietary and other influences on dental size and maturation in the newborn primate. © 2015 Wiley Periodicals, Inc.

TNF-α Upregulates Expression of BMP-2 and BMP-3 Genes in the Rat Dental Follicle – Implications for Tooth Eruption

Science.gov (United States)

Yao, Shaomian; Prpic, Veronica; Pan, Fenghui; Wise, Gary E.

2011-01-01

The dental follicle appears to regulate both the alveolar bone resorption and bone formation needed for tooth eruption. Tumor necrosis factor-alpha ( TNF-α) gene expression is maximally upregulated at postnatal day 9 in the rat dental follicle of the 1st mandibular molar, a time that correlates with rapid bone growth at the base of the tooth crypt, as well as a minor burst of osteoclastogenesis. TNF-α expression is correlated with the expression of bone morphogenetic protein-2 (BMP-2), a molecule expressed in the dental follicle that can promote bone formation. Because BMP-2 signaling may be augmented by bone morphogenetic protein-3 (BMP-3), it was the objective of this study to determine 1) if the dental follicle expresses BMP-3 and 2) if TNF-α stimulates the dental follicle cells to express BMP-2 and BMP-3. Dental follicles were collected from different postnatal ages of rat pups. Dental follicle cells were incubated with TNF-α to study its dosage and time-course effects on gene expression of BMP-2 and BMP-3, as determined by real-time RT-PCR. Next, immunostaining was conducted to confirm if the protein was synthesized and ELISA of the conditioned medium was conducted to determine if BMP-2 was secreted. We found that BMP-3 expression is correlated with the expression of TNF-α in the dental follicle and TNF-α significantly increased BMP-2 and BMP-3 expression in vitro. Immunostaining and ELISA showed that BMP-2 and BMP-3 were synthesized and secreted. This study suggests that TNF-α can upregulate the expression of bone formation genes that may be needed for tooth eruption. PMID:20067418

Autogenous tooth transplantation: an alternative to replace extracted tooth

Directory of Open Access Journals (Sweden)

David B. Kamadjaja

2015-09-01

Full Text Available Background: The gold standard treatment to replace missing tooth is dental implants, however, in certain cases, such as in young patients its placement is contraindicated. Autogenous tooth transplantation, which has been widely done in Scandinavian countries for many years, may become a good alternative to overcome this problem. Purpose: This article attempted to provide information about the indication, treatment planning, surgical technique and the successful result of autogenous tooth transplantation. Case: A fifteen year old male patient presented with large caries and periapical disease of his lower left first molar, which was partially erupted and the roots was not fully formed in radiograph. Case management: Autogenous tooth transplantation procedure was performed consisting of extraction of #36, odontectomy of #38 followed by its implantation to socket #36 and fixation of the transplanted tooth to the adjacent teeth. Post operative evaluation was done on regular basis within 18 months period. There was no complaint, the tooth was clinically stable and no evidence of periodontal problem. Serial radiographs showed healing of alveolar bone and periodontal tissue, and the complete root formation was evident by 18 months post operatively. Conclusion: Autogenous tooth transplantation is a potential alternative to replace extracted tooth. Provided that the case be properly planned and operation carefully performed, successful result of this treatment can be achieved.

Consequences of magma eruption dynamics: Intraflow variations in petrography and mineral chemistry within a single eruptive unit from Whitewater Canyon, Oregon

Science.gov (United States)

Ustunisik, G. K.; Nielsen, R. L.

2012-12-01

Individual lava flows are sometimes characterized by progressive changes in petrography and mineral chemistry which have been attributed to progressive magma chamber evacuation. In the case of Whitewater Canyon flow, a glacially quenched andesite unit on the NW flank of Mt. Jefferson, significant changes have been observed in phenocryst content and mineral chemistry within a transect from the early erupted components (inferred by flow morphology to be quenched against glacial ice ~10000 ybp), to the top of the 30 m thick flow unit. With the increasing distance from the quenched interface, the matrix changes from glassy to microcrystalline. The matrix material is generally similar in composition to the glassy melt inclusions rhyolitic in composition yet relatively degassed (lower Cl, S). Based on their morphology, we have identified at least 4 populations of plagioclase phenocrysts within the single flow: (1) Relatively unzoned high An cores (>An80) with oscillatory overgrowth, (2) Lower An cores (An50-60), associated with dacitic melt inclusions, (3) Cellular low An cores (An50-60) with higher An overgrowths (~An65-75), and (4) Lath shaped, sometimes oscillatory zoned moderately high An phenocrysts (An65-75) -often associated with olivine:cpx:plagioclase glomerocrysts. Melt inclusions are present in orthopyroxene and plagioclase, but only in the earliest erupted samples (within 5-10 meters of the quenched interface). This mafic component, characterized by olivine, intermediate plagioclase (An60-75), clinopyroxene, orthopyroxene, and oxides, was present at a range of scales from glomerocrysts to 10 cm+ enclaves. Amphibole and quartz are present only in samples from the interior of the flow unit. The width of reaction rims on amphibole increase as one progress upwards towards the flow interior. Our initial conclusions are this eruptive unit represents the progressive evacuation of a shallow magma chamber where the upper parts of the chamber had already been partially

An Erupted Dilated Odontoma: A Rare Presentation

Directory of Open Access Journals (Sweden)

Gaurav Sharma

2016-01-01

Full Text Available A dilated odontoma is an extremely rare developmental anomaly represented as a dilatation of the crown and root as a consequence of a deep, enamel-lined invagination and is considered a severe variant of dens invaginatus. An oval shape of the tooth lacking morphological characteristics of a crown or root implies that the invagination happened in the initial stages of morphodifferentiation. Spontaneous eruption of an odontoma is a rare occurrence and the occurrence of a dilated odontoma in a supernumerary tooth is even rarer with only a few case reports documented in the English literature. We present an extremely rare case of erupted dilated odontoma occurring in the supernumerary tooth in anterior maxillary region in an 18-year-old male, which, to the best of our knowledge, is the first ever case reported in English literature.

The evaluation of zinc and copper content in tooth enamel without any pathological changes - an in vitro study.

Science.gov (United States)

Klimuszko, Elzbieta; Orywal, Karolina; Sierpinska, Teresa; Sidun, Jarosław; Golebiewska, Maria

2018-01-01

The objectives of the study were to evaluate the content of copper and zinc in individual layers of tooth enamel and to analyze the relationships between the study minerals in individual layers of tooth enamel. Fifteen human permanent teeth were cut off every 150 μm alongside the labial surface. Acid biopsy of each layer was performed. The zinc content was determined using the air-acetylene flame method. The copper content was determined using the electrothermal technique with argon. The mean zinc concentrations increased significantly starting from the outer enamel surface, with the maximum concentration in the 150-300 μm layer. The mean copper concentrations increased substantially from the outer enamel surface to a depth of 150 μm, and then a slight downward trend of this mineral levels was seen, down to a depth of 450 μm. Strong positive correlation was found between the zinc and copper concentrations at depths of 150-300, 450-600 and 600-750 μm. The levels of zinc and copper in the outer enamel layers may have an effect on the increased content of unipolar minerals at deeper enamel layers. The content of the study elements determined may reflect the process of mineralization and maturation of enamel in the pre-eruption period.

Erupted complex composite odontoma: Report of two atypical cases

Directory of Open Access Journals (Sweden)

Preeti Tomar Bhattacharya

2015-01-01

Full Text Available Odontomas are nonaggressive, hamartomatous developmental malformations of odontogenic origin. They are considered one of the most common odontogenic lesions composed by diverse dental tissues. They may interfere with the eruption of an associated tooth and are more prevalent in the posterior mandible. The eruption of a complex odontoma into the oral cavity is rare. Here, we report such two rare cases of gigantic erupted complex composite odontomas.

MyD88 expression in the rat dental follicle: Implications for osteoclastogenesis and tooth eruption

Science.gov (United States)

Liu, Dawen; Yao, Shaomian; Wise, Gary E.

2010-01-01

Myeloid differentiation factor 88 (MyD88) is a key adaptor molecule in the interleukin-1 (IL-1) and IL-18 Toll-like receptor signaling pathway. Because it is present in dental follicle (DF) cells in vitro, the purpose of this study was to determine its chronological expression in vivo, as well as its possible role in osteoclastogenesis and tooth eruption. An oligo DNA microarray was used to determine gene expression of MyD88 in vivo in the DFs from the first mandibular molars of postnatal rats from days 1–11. The results showed that MyD88 was expressed maximally at day 3. Using siRNA to knock down MyD88 expression in the DF cells also reduced the gene expression of nuclear factor-kappa B-1 (NFKB1) and monocyte chemoattractant protein 1 (MCP-1). IL-1α up-regulated the expression of NFKB1, MCP-1 and receptor activator of nuclear factor kappa B ligand (RANKL), but knockdown of MyD88 nullified this IL-1α effect. Conditioned medium from DF cells with MyD88 knocked down reduced chemotactic activity for mononuclear cells and reduced osteoclastogenesis as opposed to controls. In conclusion, the maximal expression of MyD88 at day 3 in the DF may contribute to the major burst of osteoclastogenesis needed for eruption by up-regulating MCP-1 and RANKL expression. PMID:20662905

FAM20A Gene Mutation: Amelogenesis or Ectopic Mineralization?

Directory of Open Access Journals (Sweden)

Guilhem Lignon

2017-05-01

Full Text Available Background and objective:FAM20A gene mutations result in enamel renal syndrome (ERS associated with amelogenesis imperfecta (AI, nephrocalcinosis, gingival fibromatosis, and impaired tooth eruption. FAM20A would control the phosphorylation of enamel peptides and thus enamel mineralization. Here, we characterized the structure and chemical composition of unerupted tooth enamel from ERS patients and healthy subjects.Methods: Tooth sections were analyzed by Scanning Electron Microscopy (SEM, Energy Dispersive Spectroscopy (EDS, X-Ray Diffraction (XRD, and X-Ray Fluorescence (XRF.Results: SEM revealed that prisms were restricted to the inner-most enamel zones. The bulk of the mineralized matter covering the crown was formed by layers with varying electron-densities organized into lamellae and micronodules. Tissue porosity progressively increased at the periphery, ending with loose and unfused nanonodules also observed in the adjoining soft tissues. Thus, the enamel layer covering the dentin in all ERS patients (except a limited layer of enamel at the dentino-enamel junction displayed an ultrastructural globular pattern similar to one observed in ectopic mineralization of soft tissue, notably in the gingiva of Fam20a knockout mice. XRD analysis confirmed the existence of alterations in crystallinity and composition (vs. sound enamel. XRF identified lower levels of calcium and phosphorus in ERS enamel. Finally, EDS confirmed the reduced amount of calcium in ERS enamel, which appeared similar to dentin.Conclusion: This study suggests that, after an initial normal start to amelogenesis, the bulk of the tissue covering coronal dentin would be formed by different mechanisms based on nano- to micro-nodule aggregation. This evocated ectopic mineralization process is known to intervene in several soft tissues in FAM20A gene mutant.

FAM20A Gene Mutation: Amelogenesis or Ectopic Mineralization?

Science.gov (United States)

Lignon, Guilhem; Beres, Fleur; Quentric, Mickael; Rouzière, Stephan; Weil, Raphael; De La Dure-Molla, Muriel; Naveau, Adrien; Kozyraki, Renata; Dessombz, Arnaud; Berdal, Ariane

2017-01-01

Background and objective: FAM20A gene mutations result in enamel renal syndrome (ERS) associated with amelogenesis imperfecta (AI), nephrocalcinosis, gingival fibromatosis, and impaired tooth eruption. FAM20A would control the phosphorylation of enamel peptides and thus enamel mineralization. Here, we characterized the structure and chemical composition of unerupted tooth enamel from ERS patients and healthy subjects. Methods: Tooth sections were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF). Results: SEM revealed that prisms were restricted to the inner-most enamel zones. The bulk of the mineralized matter covering the crown was formed by layers with varying electron-densities organized into lamellae and micronodules. Tissue porosity progressively increased at the periphery, ending with loose and unfused nanonodules also observed in the adjoining soft tissues. Thus, the enamel layer covering the dentin in all ERS patients (except a limited layer of enamel at the dentino-enamel junction) displayed an ultrastructural globular pattern similar to one observed in ectopic mineralization of soft tissue, notably in the gingiva of Fam20a knockout mice. XRD analysis confirmed the existence of alterations in crystallinity and composition (vs. sound enamel). XRF identified lower levels of calcium and phosphorus in ERS enamel. Finally, EDS confirmed the reduced amount of calcium in ERS enamel, which appeared similar to dentin. Conclusion: This study suggests that, after an initial normal start to amelogenesis, the bulk of the tissue covering coronal dentin would be formed by different mechanisms based on nano- to micro-nodule aggregation. This evocated ectopic mineralization process is known to intervene in several soft tissues in FAM20A gene mutant.

SM50 repeat-polypeptides self-assemble into discrete matrix subunits and promote appositional calcium carbonate crystal growth during sea urchin tooth biomineralization.

Science.gov (United States)

Mao, Yelin; Satchell, Paul G; Luan, Xianghong; Diekwisch, Thomas G H

2016-01-01

The two major proteins involved in vertebrate enamel formation and echinoderm sea urchin tooth biomineralization, amelogenin and SM50, are both characterized by elongated polyproline repeat domains in the center of the macromolecule. To determine the role of polyproline repeat polypeptides in basal deuterostome biomineralization, we have mapped the localization of SM50 as it relates to crystal growth, conducted self-assembly studies of SM50 repeat polypeptides, and examined their effect on calcium carbonate and apatite crystal growth. Electron micrographs of the growth zone of Strongylocentrotus purpuratus sea urchin teeth documented a series of successive events from intravesicular mineral nucleation to mineral deposition at the interface between tooth surface and odontoblast syncytium. Using immunohistochemistry, SM50 was detected within the cytoplasm of cells associated with the developing tooth mineral, at the mineral secreting front, and adjacent to initial mineral deposits, but not in muscles and ligaments. Polypeptides derived from the SM50 polyproline alternating hexa- and hepta-peptide repeat region (SM50P6P7) formed highly discrete, donut-shaped self-assembly patterns. In calcium carbonate crystal growth studies, SM50P6P7 repeat peptides triggered the growth of expansive networks of fused calcium carbonate crystals while in apatite growth studies, SM50P6P7 peptides facilitated the growth of needle-shaped and parallel arranged crystals resembling those found in developing vertebrate enamel. In comparison, SM50P6P7 surpassed the PXX24 polypeptide repeat region derived from the vertebrate enamel protein amelogenin in its ability to promote crystal nucleation and appositional crystal growth. Together, these studies establish the SM50P6P7 polyproline repeat region as a potent regulator in the protein-guided appositional crystal growth that occurs during continuous tooth mineralization and eruption. In addition, our studies highlight the role of species

The junctional epithelium originates from the odontogenic epithelium of an erupted tooth.

Science.gov (United States)

Yajima-Himuro, Sara; Oshima, Masamitsu; Yamamoto, Gou; Ogawa, Miho; Furuya, Madoka; Tanaka, Junichi; Nishii, Kousuke; Mishima, Kenji; Tachikawa, Tetsuhiko; Tsuji, Takashi; Yamamoto, Matsuo

2014-05-02

The junctional epithelium (JE) is an epithelial component that is directly attached to the tooth surface and has a protective function against periodontal diseases. In this study, we determined the origin of the JE using a bioengineered tooth technique. We transplanted the bioengineered tooth germ into the alveolar bone with an epithelial component that expressed green fluorescence protein. The reduced enamel epithelium from the bioengineered tooth fused with the oral epithelium, and the JE was apparently formed around the bioengineered tooth 50 days after transplantation. Importantly, the JE exhibited green fluorescence for at least 140 days after transplantation, suggesting that the JE was not replaced by oral epithelium. Therefore, our results demonstrated that the origin of the JE was the odontogenic epithelium, and odontogenic epithelium-derived JE was maintained for a relatively long period.

Treatment of ectopically erupting maxillary permanent first molars with a distal extended stainless steel crown.

Science.gov (United States)

Roberts, M W

1986-01-01

The exaggerated mesial eruption of the permanent first molar can result in the tooth becoming impacted, or the premature atypical resorption and exfoliation of the primary molar, with a resultant loss of space. A stainless steel crown with a distal guide plane was placed on a primary molar to correct the aberrant eruption angle of the permanent tooth. This procedure can be used successfully for both partially and totally tissue-impacted teeth, and is described in this report.

Photothermal stress triggered by near-infrared-irradiated carbon nanotubes up-regulates osteogenesis and mineral deposition in tooth-extracted sockets.

Science.gov (United States)

Kajiya, Hiroshi; Katsumata, Yuri; Sasaki, Mina; Tsutsumi, Takashi; Kawaguchi, Minoru; Fukushima, Tadao

2015-01-01

The bone regenerative healing process is often prolonged, with a high risk of infection particularly in elderly and diseased patients. A reduction in healing process time usually requires mechanical stress devices, chemical cues, or laser/thermal therapies. Although these approaches have been used extensively for the reduction of bone healing time, the exact mechanisms involved in thermal stress-induced bone regeneration remain unclear. Photothermal stress (PTS) stimulation was carried out using a novel photothermal device, composed of an alginate gel (AG) including carbon nanotubes (CNT-AGs) and their irradiator with near-infrared (NIR) light. We investigated the effects of optimal hyperthermia on osteogenesis, its signalling pathway in vitro and mineral deposition in tooth-extracted sockets in vivo. The PTS (10 min at 42 °C, every day), triggered by NIR-induced CNT, increased the activity of alkaline phosphatase (ALP) in mouse osteoblast MC3T3-E1 cells in a time-dependent manner compared with the non-thermal stress control. PTS significantly induced the expression of osteogenic-related molecules such as ALP, RUNX2 and Osterix in a time-dependent manner with phosphorylated mitogen-activated protein kinases (MAPK). PTS increased the expression of heat shock factor (HSF) 2, but not HSF1, resulting in activation of heat shock protein 27. PTS significantly up-regulated mineral deposition in tooth-extracted sockets in normal and ovariectomised osteoporotic model mice in vivo. Our novel CNT-based PTS up-regulated osteogenesis via activation of heat shock-related molecules, resulting in promotion of mineral deposition in enhanced tooth-extracted sockets.

Eruption Cyst in the Neonate.

Science.gov (United States)

de Oliveira, Alline J; Silveira, Maria Lg; Duarte, Danilo A; Diniz, Michele B

2018-01-01

The pediatric dental approach to the oral cavity of newborns requires special attention, as many aspects are unique and peculiar to this period of life. It is important that pediatricians and pediatric dentists be aware of the characteristics within normal newborn patterns and prepared to make a correct diagnosis of abnormalities at early stages. Congenital eruption cysts (ECs) are rarely observed in newborns, as at this stage of a child's life, tooth eruption is unusual. This study reports a case of EC treated successfully by monitoring of the lesion, without any surgical procedure. In the 4th month, the lesion had completely regressed, and the deciduous central incisors had erupted without problems. The clinical and radiographic monitoring of ECs in newborns seems to be a satisfactory management procedure, similar to what is recommended for older children. How to cite this article: de Oliveira AJ, Silveira MLG, Duarte DA, Diniz MB. Eruption Cyst in the Neonate. Int J Clin Pediatr Dent 2018;11(1):58-60.

Distribution of Cathepsin K in Late Stage of Tooth Germ Development and Its Function in Degrading Enamel Matrix Proteins in Mouse.

Directory of Open Access Journals (Sweden)

Tao Jiang

Full Text Available Cathepsin K (CTSK is a member of cysteine proteinase family, and is predominantly expressed in osteoclastsfor degradationof bone matrix proteins. Given the similarity in physical properties of bone and dental mineralized tissues, including enamel, dentin and cementum, CTSK is likely to take part in mineralization process during odontogenesis. On the other hand, patients with pycnodysostosis caused by mutations of the CTSK gene displayedmultipledental abnormalities, such as hypoplasia of the enamel, obliterated pulp chambers, hypercementosis and periodontal disease. Thereforeitis necessary to study the metabolic role of CTSK in tooth matrix proteins. In this study, BALB/c mice at embryonic day 18 (E18, post-natal day 1 (P1, P5, P10 and P20 were used (5 mice at each time pointfor systematic analyses of CTSK expression in the late stage of tooth germ development. We found that CTSK was abundantly expressed in the ameloblasts during secretory and maturation stages (P5 and P10 by immunohistochemistry stainings.During dentinogenesis, the staining was also intense in the mineralization stage (P5 and P10,but not detectable in the early stage of dentin formation (P1 and after tooth eruption (P20.Furthermore, through zymography and digestion test in vitro, CTSK was proved to be capable of hydrolyzing Emdogain and also cleaving Amelogenininto multiple products. Our resultsshed lights on revealing new functions of CTSK and pathogenesis of pycnodysostosis in oral tissues.

Understanding the eruption mechanisms of the explosive Bellecombe Eruptions on Piton de la Fournaise, La Réunion

Science.gov (United States)

Morgan, K.; Ort, M. H.; Di Muro, A.; Parnell, R. A.; Huff, W. D.

2017-12-01

Piton de la Fournaise (PdF) is an active basaltic volcano on La Réunion island. The Bellecombe Tephra was deposited from at least three unusually explosive eruptions between 3000-5000 ka. The Bellecombe eruptions were interpreted recently to have been due to rapid depressurization of the hydrothermal system when a deep fracture opened after lateral, seaward-directed sliding of the eastern flank, late in a large effusive eruption. This project tests this hypothesis by physically, mineralogically, and chemically characterizing the Bellecombe Tephra to look for evidence of the involvement of the PdF hydrothermal system in the eruptions and understand where the eruptions initiated. The Bellecombe tephra consists of three units separated by incipient soils. Both the Upper and Lower Bellecombe deposits are mostly medium to very fine ash. Lower Bellecombe deposits, from the first two eruptions, are mostly beds of glassy ash containing minor lithic grains and olivine crystals. Hydrothermal minerals, mostly smectite, are present in a few Lower Bellecombe beds. Since these minerals are only present in some beds, the smectite formed before deposition rather than as a product of surficial alteration. The Upper Bellecombe deposits record a third eruption and vary between clast-supported crystal- and lithic-rich lapilli beds and ash beds with abundant ash pellets. The crystals are mostly olivine, with lesser pyroxene and plagioclase and sparse hydrothermal quartz. Gabbro and oceanite clasts are abundant and trachytic pumice rare in these deposits. Hydrothermal minerals are common in most Upper Bellecombe beds. The presence of smectite in some of the Lower Bellecombe beds suggests these deposits came from a system below 200 ºC. Clays in the Upper Bellecombe beds - smectite and mixed layer R0 illite/smectite - imply a system at 40-140 ºC. The hydrothermal system was involved, but might not have been the primary impetus for these eruptions, since hydrothermal minerals are not

Prediction of Un-erupted Canine and Premolar Tooth Size in Mixed Dentition among Bangladeshi Population.

Science.gov (United States)

Chokrobrty, R; Rafique, T; Ghosh, R; Biswas, A K; Sajedeen, M; Hassan, G S

2017-10-01

Accurate prediction of the space available to accommodate the size of the un-erupted canines and premolars plays an important role in mixed dentition in Orthodontics. This Descriptive cross sectional study was carried out in the Department of Orthodontics of Bangabandhu Sheikh Mujib Medical University from July 2014 to June 2015. Dental study models of 140 patients were taken as sample. The sample was consisted of 54 Bangladeshi males and 86 females aged between 12 to 17 years and without any previous orthodontic treatment fully erupted permanent teeth and with no dental anomalies were recruited. The study was done by measuring the mesio-distal dimensions of teeth over the dental cast. A pre-structured data collection form which includes the particulars of the patient and data was filled. All patients were having a serial number to maintain their confidentiality. The study protocol was approved by "Institutional Review Board" of Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. Un-paired t test were used to examine differences between genders, correlation coefficients and linear regression equations were used to carry out the analysis. Descriptive statistics including means, standard deviations, and minimum-maximum values were calculated. Unpaired sample 't' tests were carried out to compare tooth size between the sexes. Logistic regression for development of new prediction formula on the basis of study sample of our population. Pearson correlation coefficient test for found the correlation between mandibular incisors and mandibular and maxillary canine and premolars in each quadrant. The difference between the present study with that of Moyers and Tanaka and Johnston were statistically significant (p<0.001). The values from Moyers and Tanaka and Johnston methods exceed while comparing to Bangladeshi population. Therefore, Moyers and Tanaka and Johnston method of prediction are not applicable for our population.

Tooth development in Ambystoma mexicanum: phosphatase activities, calcium accumulation and cell proliferation in the tooth-forming tissues.

Science.gov (United States)

Wistuba, Joachim; Ehmcke, Jens; Clemen, Günter

2003-06-01

Prerequisites of tooth formation, cell proliferation in the tooth-forming tissues, calcium accumulation and the enzymatic activities of alkaline (ALP) and acid phosphatases (ACP) were investigated by immunohistochemical and histochemical methods in various developmental stages of the Mexican Axolotl, Ambystoma mexicanum. During the growth of replacement teeth, the tooth-forming tissues continually recruit cells from the surrounding regions. The basal layer of the oral epithelium, the dental lamina and sometimes even the outer enamel epithelium provide cells for the differentiated inner enamel epithelium, in which the active ameloblasts are localized. The differentiating odontoblasts are derived from proliferating cells situated basally to the replacement teeth in the mesenchymal tissue. When differentiation has started and the cells have become functional, proliferative activity can no longer be observed. Calcium is accumulated close to the site of mineralization in the inner enamel epithelium and in the odontoblasts as it is in mammals, elasmobranchii and teleostei. The activities of ACP and ALP related to the mineralization of the replacement teeth are separated spatially and not sequentially as they are in mammals. However, the results indicate a similar function of these enzymatic components in relation to tooth formation and maturation of mineral deposition. Most of the substantial processes related to tooth formation reported from other vertebrates occur in a manner similar to that in Ambystoma mexicanum, but there also seem to be basic mechanisms present that are realised in a unique way in this urodele.

Contamination of tooth-colored mineral trioxide aggregate used as a root-end filling material: a bacterial leakage study.

Science.gov (United States)

Montellano, Angela M; Schwartz, Scott A; Beeson, Thomas J

2006-05-01

This experiment investigated the ability of tooth-colored mineral trioxide aggregate (MTA) to maintain an apical seal in the presence of bacteria when contaminated with blood, saline or saliva. Ninety extracted human teeth with single canals were randomly placed into six groups of 15. Canals were prepared to size 50. The apical 3 mm of each root was removed and 3 mm root-end preparations were made with a #329 bur. Root-end preparations in groups 1 through 3 were filled with MTA after contamination with blood, saline, or saliva, respectively. In group 4, uncontaminated root-end preparations were filled with MTA. Groups 5 and 6 served as negative and positive controls. A tube/tooth assembly was utilized to suspend each root end in Trypticase Soy Broth (TSB). The access chambers were filled with Staphylococcus epidermidis. Positive growth over thirty days was demonstrated by turbidity of the TSB. Vitek analysis was used to confirm the presence of S. epidermidis in the positive samples. Data evaluation consisted of a chi(2) analysis (p < 0.05). Although all experimental groups demonstrated leakage, tooth-colored MTA contaminated with saliva (group 3) leaked significantly more than the uncontaminated tooth-colored MTA (group 4) (p = 0.028).

Early Eruption of Maxillary Pre Molar with Turner's Hypoplasia in a 5-Year-Old Boy.

Science.gov (United States)

Rai, Nitya; Mathur, Shivani; Sandhu, Meera; Sachdev, Vinod

2016-08-01

Early eruption of permanent maxillary premolar appears to be a unique finding, at such an early chronological age. Untimely eruption of permanent maxillary premolar is discussed in a 5-year-old male patient. On intra oral examination grossly carious primary maxillary first molar (tooth number 54,64) were reported. The erupting teeth presented with a hypomineralized cusp tip. Extraction following space maintainer in 64 region was given. Pediatric dentist should consider these kinds of rarities in eruption pattern while examining a pediatric patient.

Tooth enamel mineralization in ungulates: implications for recovering a primary isotopic time-series

Science.gov (United States)

Passey, Benjamin H.; Cerling, Thure E.

2002-09-01

Temporal changes in the carbon and oxygen isotopic composition of an animal are an environmental and behavioral input signal that is recorded into the enamel of developing teeth. In this paper, we evaluate changes in phosphorus content and density along the axial lengths of three developing ungulate teeth to illustrate the protracted nature of mineral accumulation in a volume of developing enamel. The least mature enamel in these teeth contains by volume about 25% of the mineral mass of mature enamel, and the remaining 75% of the mineral accumulates during maturation. Using data from one of these teeth (a Hippopotamus amphibius canine), we develop a model for teeth growing at constant rate that describes how an input signal is recorded into tooth enamel. The model accounts for both the temporal and spatial patterns of amelogenesis (enamel formation) and the sampling geometry. The model shows that input signal attenuation occurs as a result of time-averaging during amelogenesis when the maturation interval is long compared to the duration of features in the input signal. Sampling does not induce significant attenuation, provided that the sampling interval is several times shorter than the maturation interval. We present a detailed δ 13C and δ 18O record for the H. amphibius canine and suggest possible input isotope signals that may have given rise to the measured isotope signal.

Accelerated enamel mineralization in Dspp mutant mice

Science.gov (United States)

Verdelis, Kostas; Szabo-Rogers, Heather L.; Xu, Yang; Chong, Rong; Kang, Ryan; Cusack, Brian J.; Jani, Priyam; Boskey, Adele L.; Qin, Chunlin; Beniash, Elia

2016-01-01

Dentin sialophosphoprotein (DSPP) is one of the major non-collagenous proteins present in dentin, cementum and alveolar bone; it is also transiently expressed by ameloblasts. In humans many mutations have been found in DSPP and are associated with two autosomal-dominant genetic diseases — dentinogenesis imperfecta II (DGI-II) and dentin dysplasia (DD). Both disorders result in the development of hypomineralized and mechanically compromised teeth. The erupted mature molars of Dspp–/– mice have a severe hypomineralized dentin phenotype. Since dentin and enamel formations are interdependent, we decided to investigate the process of enamel onset mineralization in young Dspp–/– animals. We focused our analysis on the constantly erupting mouse incisor, to capture all of the stages of odontogenesis in one tooth, and the unerupted first molars. Using high-resolution microCT, we revealed that the onset of enamel matrix deposition occurs closer to the cervical loop and both secretion and maturation of enamel are accelerated in Dspp–/– incisors compared to the Dspp+/– control. Importantly, these differences did not translate into major phenotypic differences in mature enamel in terms of the structural organization, mineral density or hardness. The only observable difference was the reduction in thickness of the outer enamel layer, while the total enamel thickness remained unchanged. We also observed a compromised dentin-enamel junction, leading to delamination between the dentin and enamel layers. The odontoblast processes were widened and lacked branching near the DEJ. Finally, for the first time we demonstrate expression of Dspp mRNA in secretory ameloblasts. In summary, our data show that DSPP is important for normal mineralization of both dentin and enamel. PMID:26780724

Tooth loss early in life suppresses neurogenesis and synaptophysin expression in the hippocampus and impairs learning in mice.

Science.gov (United States)

Kubo, Kin-Ya; Murabayashi, Chika; Kotachi, Mika; Suzuki, Ayumi; Mori, Daisuke; Sato, Yuichi; Onozuka, Minoru; Azuma, Kagaku; Iinuma, Mitsuo

2017-02-01

Tooth loss induced neurological alterations through activation of a stress hormone, corticosterone. Age-related hippocampal morphological and functional changes were accelerated by early tooth loss in senescence-accelerated mouse prone 8 (SAMP8). In order to explore the mechanism underlying the impaired hippocampal function resulting from early masticatory dysfunction due to tooth loss, we investigated the effects of early tooth loss on plasma corticosterone levels, learning ability, neurogenesis, and synaptophysin expression in the hippocampus later in life of SAMP8 mice. We examined the effects of tooth loss soon after tooth eruption (1 month of age) on plasma corticosterone levels, learning ability in the Morris water maze, newborn cell proliferation, survival and differentiation in the hippocampal dentate gyrus, and synaptophysin expression in the hippocampus of aged (8 months of age) SAMP8 mice. Aged mice with early tooth loss exhibited increased plasma corticosterone levels, hippocampus-dependent learning deficits in the Morris water maze, decreased cell proliferation, and cell survival in the dentate gyrus, and suppressed synaptophysin expression in the hippocampus. Newborn cell differentiation in the hippocampal dentate gyrus, however, was not affected by early tooth loss. These findings suggest that learning deficits in aged SAMP8 mice with tooth loss soon after tooth eruption are associated with suppressed neurogenesis and decreased synaptophysin expression resulting from increased plasma corticosterone levels, and that long-term tooth loss leads to impaired cognitive function in older age. Copyright © 2016. Published by Elsevier Ltd.

Unusually large erupted complex odontoma: A rare case report

Energy Technology Data Exchange (ETDEWEB)

Bagewadi, Shivanand B.; Kukreja, Rahul; Suma, Gundareddy N.; Yadav, Bhawn; Sharma, Havi [Dept. of Oral Medicine and Radiology, ITS Centre for Dental Studies and Research, Murad Nagar (India)

2015-03-15

Odontomas are nonaggressive, hamartomatous developmental malformations composed of mature tooth substances and may be compound or complex depending on the extent of morphodifferentiation or on their resemblance to normal teeth. Among them, complex odontomas are relatively rare tumors. They are usually asymptomatic in nature. Occasionally, these tumors become large, causing bone expansion followed by facial asymmetry. Odontoma eruptions are uncommon, and thus far, very few cases of erupted complex odontomas have been reported in the literature. Here, we report the case of an unusually large, painless, complex odontoma located in the right posterior mandible.

Cone Beam Computed Tomography Evaluation of the Periapical Status of Nonvital Tooth with Open Apex Obturated with Mineral Trioxide Aggregate: A Case Report

Directory of Open Access Journals (Sweden)

Vijay Shekhar

2013-01-01

Full Text Available Management of a tooth with open apex is a challenge to the dental practitioners. Evaluation of the periapical healing is required in such cases by radiographic techniques. The objective of this paper was to assess the healing of a periapical lesion in a non-vital tooth with open apex treated with mineral trioxide aggregate (MTA obturation using cone beam computed tomography (CBCT. The endodontic treatment of a fractured non-vital discolored maxillary left lateral incisor with an open apex was done with MTA obturation. The clinical and radiographic followup done regularly showed that the tooth was clinically asymptomatic and that the size of the periapical lesion observed by intraoral periapical (IOPA radiographs and CBCT was decreased remarkably after two years. CBCT and IOPA radiographs were found to be useful radiographic tools to assess the healing of a large periapical lesion in a non-vital tooth with open apex managed by MTA obturation.

The first permanent molar: spontaneous eruption after a five-year failure.

Science.gov (United States)

Mistry, Vinay N; Barker, Christopher S; James Spencer, R

2017-09-01

It is rare for a first permanent molar (FPM) to temporarily exhibit clinical features of failure of eruption, followed by regeneration of full eruptive capacity 5 years later. Indeterminate failure of eruption (IFE) is a diagnosis of exclusion where the distinction between primary failure of eruption (PFE) and mechanical failure of eruption (MFE) is unclear, including patients too young to specify. An 11-year-old girl attended the orthodontic clinic at Mid Yorkshire Hospitals NHS Trust regarding an unerupted lower right FPM. Her medical and dental trauma history was unremarkable. She presented with a Class II division 2 malocclusion in the mixed dentition, with all other FPMs fully erupted. This report documents that an unerupted FPM in an 11-year-old patient may still have the eruptive potential to become functional within the dentition. The period spent monitoring the FPM's outcome prior to surgical intervention has avoided an operation under general anaesthetic and potentially unnecessary orthodontic treatment, as the tooth subsequently erupted without treatment. © 2017 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes

Science.gov (United States)

2013-01-01

Background Equine incisors are subjected to continuous occlusal wear causing multiple, age related changes of the extragingival crown. It is assumed that the occlusal wear is compensated by continued tooth elongation at the apical ends of the teeth. In this study, μCT-datasets offered the opportunity to analyze the three-dimensional appearance of the extra- and intraalveolar parts of the enamel containing dental crown as well as of the enamel-free dental root. Multiple morphometric measurements elucidated age related, morphological changes within the intraalveolar part of the incisors. Results Equine incisors possess a unique enamel cover displaying large indentations on the mesial and distal sides. After eruption tooth elongation at the apical end outbalances occlusal wear for two to four years resulting in increasing incisor length in this period of time. Remarkably, this maximum length is maintained for about ten years, up to a tooth age of 13 to 15 years post eruption. Variances in the total length of individual teeth are related to different Triadan positions (central-, middle- and corner incisors) as well as to the upper and lower arcades. Conclusion Equine incisors are able to fully compensate occlusal wear for a limited period of time. However, after this ability ceases, it is expected that a diminished intraalveolar tooth length will cause massive changes in periodontal biomechanics. The time point of these morphodynamic and biomechanical changes (13 to 15 years post eruption) occurs in coincidence with the onset of a recently described destructive disease of equine incisor (equine odontoclastic tooth resorption and hypercementosis) in aged horses. However, further biomechanical, cell biological and microbiological investigations are needed to elucidate a correlation between age related changes of incisor morphology and this disease. PMID:24321365

Investigation of EPR signals on tooth enamel

Energy Technology Data Exchange (ETDEWEB)

Pavlenko, A; Mironova-Ulmane, N; Polakov, M; Riekstina, D [Institute of Solid State Physics, University of Latvia, Riga (Latvia)

2007-12-15

Calcified tissues are involved in continues metabolic process in human organism exchanging a number of chemical elements with environment. The rate of biochemical reactions is tissue dependent and the slowest one at the tooth enamel, the most mineralized tissue of human organism. The long time stability and unique chemical composition make tooth enamel suitable for number of application. The assessment of individual radiation dose by Electron Paramagnetic Resonance (EPR) and evaluations of elemental composition by Instrumentation Neutron Activation Analysis (INAA) are the well known procedures where properties of tooth enamel intensively used. The current work is focused on investigation of EPR signals and determination of chemical composition on several teeth samples having different origin. The EPR spectra and INAA element content of milk tooth, caries tooth, and paradantose tooth have been compared to each other. The results showed that the intensity of EPR signal is much higher for the caries tooth than the for paradantose tooth that is in agreement with depleted Ca content.

Tooth eruption in a patient with craniometaphyseal dysplasia: case report.

Science.gov (United States)

Hayashibara, T; Komura, T; Sobue, S; Ooshima, T

2000-10-01

Craniometaphyseal dysplasia (CMD) is a very rare genetic disorder of bone remodeling caused by osteoclast dysfunction. The clinical and radiographical features of oral findings are presented in a sporadic case of CMD in a child (age 10 years, 7 months). An intraoral examination showed severe malocclusions, including anterior crossbite and deep bite. Furthermore, a radiographic examination showed increased radiopacity of the maxilla and mandibular bones due to hyperostosis and sclerosis of the jaw. There was no root resorption of the canines or molars in the primary dentition, although root formation of the permanent teeth was proceeding. Dental age was calculated to be approximately 1 year, 4 months younger than his chronological age. The eruption speed of the permanent lateral incisors after the gingival emergence was shown to be within normal values, and we discuss whether the canines and premolars in the permanent dentition could erupt or not.

Factors influencing patients' choice of treatment for a tooth with ...

African Journals Online (AJOL)

Dental caries is a post eruptive pathologic process of bacterial origin involving the dissolution of dental hard tissues with resultant cavity formation and it may progress to irreversible pulpitis and apical periodontitis. The options for managing involved teeth include pulp therapy and tooth extraction. Despite the high success ...

Relative tooth size at birth in primates: Life history correlates.

Science.gov (United States)

Smith, Timothy D; Muchlinski, Magdalena N; Bucher, Wade R; Vinyard, Christopher J; Bonar, Christopher J; Evans, Sian; Williams, Lawrence E; DeLeon, Valerie B

2017-11-01

Dental eruption schedules have been closely linked to life history variables. Here we examine a sample of 50 perinatal primates (28 species) to determine whether life history traits correlate with relative tooth size at birth. Newborn primates were studied using serial histological sectioning. Volumes of deciduous premolars (dp 2 -dp 4 ), replacement teeth (if any), and permanent molars (M 1-2/3 ) of the upper jaw were measured and residuals from cranial length were calculated with least squares regressions to obtain relative dental volumes (RDVs). Relative dental volumes of deciduous or permanent teeth have an unclear relationship with relative neonatal mass in all primates. Relative palatal length (RPL), used as a proxy for midfacial size, is significantly, positively correlated with larger deciduous and permanent postcanine teeth. However, when strepsirrhines alone are examined, larger RPL is correlated with smaller RDV of permanent teeth. In the full sample, RDVs of deciduous premolars are significantly negatively correlated with relative gestation length (RGL), but have no clear relationship with relative weaning age. RDVs of molars lack a clear relationship with RGL; later weaning is associated with larger molar RDV, although correlations are not significant. When strepsirrhines alone are analyzed, clearer trends are present: longer gestations or later weaning are associated with smaller deciduous and larger permanent postcanine teeth (only gestational length correlations are significant). Our results indicate a broad trend that primates with the shortest RGLs precociously develop deciduous teeth; in strepsirrhines, the opposite trend is seen for permanent molars. Anthropoids delay growth of permanent teeth, while strepsirrhines with short RGLs are growing replacement teeth concurrently. A comparison of neonatal volumes with existing information on extent of cusp mineralization indicates that growth of tooth germs and cusp mineralization may be selected for

Stability of interceptive/corrective orthodontic treatment for tooth ankylosis and Class II mandibular deficiency: A case report with 10 years follow-up

OpenAIRE

Carlos Henrique Guimarães; José Fernando Castanha Henriques; Guilherme Janson; Wilana S Moura

2015-01-01

The purpose of this article is to present the treatment of a 8-year-old boy with tooth ankylosis in teeth 85 and Class II division 1 malocclusion and to report a 10-year follow-up result. The patient was initially treated with a sagittal removable appliance, followed by an eruption guidance appliance and braces. The interceptive orthodontic treatment performed to recover the space lost by ankylosis of a deciduous tooth allowed a spontaneous eruption and prevented progression of the problem. T...

Genome-Wide Association Study Identifies Four Loci Associated with Eruption of Permanent Teeth

Science.gov (United States)

Zhang, Hao; Shaffer, John R.; Hansen, Thomas; Esserlind, Ann-Louise; Boyd, Heather A.; Nohr, Ellen A.; Timpson, Nicholas J.; Fatemifar, Ghazaleh; Paternoster, Lavinia; Evans, David M.; Weyant, Robert J.; Levy, Steven M.; Lathrop, Mark; Smith, George Davey; Murray, Jeffrey C.; Olesen, Jes; Werge, Thomas; Marazita, Mary L.; Sørensen, Thorkild I. A.; Melbye, Mads

2011-01-01

The sequence and timing of permanent tooth eruption is thought to be highly heritable and can have important implications for the risk of malocclusion, crowding, and periodontal disease. We conducted a genome-wide association study of number of permanent teeth erupted between age 6 and 14 years, analyzed as age-adjusted standard deviation score averaged over multiple time points, based on childhood records for 5,104 women from the Danish National Birth Cohort. Four loci showed association at Peruption and were also known to influence height and breast cancer, respectively. The two other loci pointed to genomic regions without any previous significant genome-wide association study results. The intronic SNP rs7924176 in ADK could be linked to gene expression in monocytes. The combined effect of the four genetic variants was most pronounced between age 10 and 12 years, where children with 6 to 8 delayed tooth eruption alleles had on average 3.5 (95% confidence interval: 2.9–4.1) fewer permanent teeth than children with 0 or 1 of these alleles. PMID:21931568

An evaluation of third molar eruption for assessment of chronologic age: A panoramic study.

Science.gov (United States)

Tuteja, Monica; Bahirwani, Shraddha; Balaji, P

2012-01-01

The identity of a person can be established by assessing one's age, and in order to be entitled to civil rights and social benefits, verification of the chronological age is required and thereby age estimation has gained an increasing significance in recent years. Tooth eruption is one of the criteria of developmental morphology that can be evaluated by either clinical examination or by evaluation of dental radiographs to determine the dental age. The present study was aimed to evaluate the reliability of the third molar eruption stage as a parameter for forensic age estimation in living subjects. The stage of wisdom tooth eruption in 77 male and 73 female Indian subjects aged between 12-26 years was determined by subjecting them to conventional orthopantomograms and was interpreted to assess the third molar eruption stages to evaluate the dental age. Predicted minimum age and mean age of the study sample were found to be significant predictors (Page. Minimum age was able to explain 58.3% of the variation in actual age and the mean age was able to explain 60.3% of variation in actual age. Third molar is fairly a reliable indicator to determine the age of alveolar, gingival, and complete emergence of third molar in the occlusal plane in adolescents and young adults. Minimum and most probable ages of examined subjects can also be evaluated using third molar eruption stage.

An Unusual Erupted Complex Composite Odontoma: A Rare Case

Directory of Open Access Journals (Sweden)

Dawasaz Ali Azhar

2013-01-01

Full Text Available Odontomas are malformations of the dental tissues and may interfere with the eruption of the associated tooth. Complex composite odontoma (CO was described as a distinct entity for the first time by Broca in 1866. This lesion takes place due to the developmental disturbances where the dental components are laid down in a disorganized manner, due to failure of normal morphodifferentiation. Very few cases of erupted complex composite odontomas have been reported in the literature. The case reported here is of an odontoma found in the left mandibular body, associated with an impacted second molar of a 17-year-old Saudi male. Under local anesthesia the odontoma was surgically removed. Histopathological examination confirmed the diagnosis of CO. The impacted second molar which was left in the mandibular body erupted clinically after 6 months. Erupted CO is rarely seen in the mandibular left body. The early diagnosis, followed by a proper treatment at the right time, will result in a favorable prognosis.

Development of the canine tooth in the beagle

International Nuclear Information System (INIS)

Amimoto, A.; Iwamoto, S.; Hachimura, H.; Miyamoto, T.; Murata, T.; Taura, Y.; Nakama, S.; Hayashi, K.

1993-01-01

The growth of the crown and root in the canine tooth of beagle dogs were observed macroscopically and radiographically, and changes of occlusion with age were investigated. Completion of growth in the crown of the canine tooth was observed in both mandible and maxilla, and its eruption was accompanied by development of the dental root. The permanent canine erupted on the lingual side of deciduous canine in the mandible, and on the mesial side of the deciduous canine in the maxilla. Movement of the permanent canine to normal occlusal position(buccal direction in mandibular canine, and distal direction in maxillary canine)was followed by the loss of the deciduous canine. Coexistence of the permanent and deciduous canines occurred for about 2.4 weeks in the maxilla and about 1.4 weeks in the mandible, on average. Macroscopically, the growth of the permanent canine was completed by 33 weeks of age in the mandible and about 34 weeks of age in the maxilla. The mature root of the permanent canine was recognized radiographically at about 43 weeks of age in the mandible and 47 weeks of age in the maxilla

X-ray micro-analysis of the mineralization patterns in developing enamel in hamster tooth germs exposed to fluoride in vitro during the secretory phase of amelogenesis

International Nuclear Information System (INIS)

Lyaruu, D.M.; Blijleven, N.; Hoeben-Schornagel, K.; Bronckers, A.L.; Woeltgens, J.H.

1989-01-01

The developing enamel from three-day-old hamster first maxillary (M1) molar tooth germs exposed to fluoride (F-) in vitro was analyzed for its mineral content by means of the energy-dispersive x-ray microanalysis technique. The aim of this study was to obtain semi-quantitative data on the F(-)-induced hypermineralization patterns in the enamel and to confirm that the increase in electron density observed in micrographs of F(-)-treated enamel is indeed due to an increase in mineral content in the fluorotic enamel. The tooth germs were explanted during the early stages of secretory amelogenesis and initially cultured for 24 hr in the presence of 10 ppm F- in the culture medium. The germs were then cultured for another 24 hr without F-. In order to compare the ultrastructural results directly with the microprobe data, we used the same specimens for both investigations. The net calcium counts (measurement minus background counts) in the analyses were used as a measure of the mineral content in the enamel. The aprismatic pre-exposure enamel, deposited in vivo before the onset of culture, was the most hypermineralized region in the fluorotic enamel, i.e., it contained the highest amount of calcium measured. The degree of the F(-)-induced hypermineralization gradually decreased (but was not abolished) in the more mature regions of the enamel. The unmineralized enamel matrix secreted during the initial F- treatment in vitro mineralized during the subsequent culture without F-. The calcium content in this enamel layer was in the same order of magnitude as that recorded for the newly deposited enamel in control tooth germs cultured without F-

Neuroendocrine alterations impair enamel mineralization, tooth eruption and saliva in rats Alterações neuroendócrinas interferem com a mineralização do esmalte, a erupção dentária e a saliva em ratos

Directory of Open Access Journals (Sweden)

Kikue Takebayashi Sassaki

2003-03-01

Full Text Available Neonatal administration of monosodium glutamate (MSG in rats causes definite neuroendocrine disturbances which lead to alterations in many organ systems. The possibility that MSG could affect tooth and salivary gland physiology was examined in this paper. Male and female pups were injected subcutaneously with MSG (4 mg/g BW once a day at the 2nd, 4th, 6th, 8th and 10th day after birth. Control animals were injected with saline, following the same schedule. Lower incisor eruption was determined between the 4th and the 10th postnatal days, and the eruption rate was measured between the 43rd and the 67th days of age. Pilocarpine-stimulated salivary flow was measured at 3 months of age; protein and amylase contents were thereby determined. The animals treated with MSG showed significant reductions in the salivary flow (males, -27%; females, -40% and in the weight of submandibular glands (about -12%. Body weight reduction was only about 7% for males, and did not vary in females. Saliva of MSG-treated rats had increased concentrations of total proteins and amylase activity. The eruption of lower incisors occurred earlier in MSG-treated rats than in the control group, but on the other hand the eruption rate was significantly slowed down. The incisor microhardness was found to be lower than that of control rats. Our results show that neonatal MSG treatment causes well-defined oral disturbances in adulthood in rats, including salivary flow reduction, which coexisted with unaltered protein synthesis, and disturbances of dental mineralization and eruption. These data support the view that some MSG-sensitive hypothalamic nuclei have an important modulatory effect on the factors which determine caries susceptibility.A administração neonatal de glutamato monossódico (MSG em ratos provoca distúrbios neuroendócrinos que acarretam alterações em vários sistemas orgânicos. Neste trabalho, avaliamos as repercussões desse tratamento sobre dentes e gl

Case report: Management of severe posterior open bite due to primary failure of eruption.

LENUS (Irish Health Repository)

Mc Cafferty, J

2010-06-01

Primary failure of tooth eruption (PFE) is a rare condition affecting any or all posterior quadrants. Unilateral involvement of maxillary and mandibular quadrants causes a dramatic posterior open bite that requires complex management strategies.

Genome-wide association study identifies four loci associated with eruption of permanent teeth

DEFF Research Database (Denmark)

Geller, Frank; Feenstra, Bjarke; Zhang, Hao

2011-01-01

The sequence and timing of permanent tooth eruption is thought to be highly heritable and can have important implications for the risk of malocclusion, crowding, and periodontal disease. We conducted a genome-wide association study of number of permanent teeth erupted between age 6 and 14 years......, analyzed as age-adjusted standard deviation score averaged over multiple time points, based on childhood records for 5,104 women from the Danish National Birth Cohort. Four loci showed association at P...

Stability of interceptive/corrective orthodontic treatment for tooth ankylosis and Class II mandibular deficiency: A case report with 10 years follow-up.

Science.gov (United States)

Guimarães, Carlos Henrique; Henriques, José Fernando Castanha; Janson, Guilherme; Moura, Wilana S

2015-01-01

The purpose of this article is to present the treatment of a 8-year-old boy with tooth ankylosis in teeth 85 and Class II division 1 malocclusion and to report a 10-year follow-up result. The patient was initially treated with a sagittal removable appliance, followed by an eruption guidance appliance and braces. The interceptive orthodontic treatment performed to recover the space lost by ankylosis of a deciduous tooth allowed a spontaneous eruption and prevented progression of the problem. The use of an eruption-guidance appliance corrected the dentoskeletal Class II, thus improving the patient's appearance. Besides the treatment producing a good occlusal relationship with the Class I molar, the correction of the overjet and overbite was stable over a ten-year period.

Expression of EMAP-II in the rat dental follicle and its potential role in tooth eruption

Science.gov (United States)

Liu, Dawen; Wise, Gary E.

2008-01-01

Endothelial monocyte-activating polypeptide II (EMAP-II) is an inflammatory cytokine with chemotactic activity. Because the dental follicle (DF) recruits mononuclear cells (osteoclast precursors) to promote the osteoclastogenesis needed for tooth eruption, it was the aim of this study to determine if EMAP-II may contribute to this recruitment. Using a DNA microarray, EMAP-II was found to be highly expressed in vivo in the DFs of day 1 to day 11 postnatal rats, with its expression elevated at days 1 and 3. Using a siRNA to knock down EMAP-II expression also resulted in a reduction in expression of CSF-1 and MCP-1 in the DF cells. Addition of EMAP-II protein to the DF cells partially restored the expression of CSF-1 and MCP-1. In chemotaxis assays using either conditioned medium of the DF cells with anti-EMAP-II antibody added or conditioned medium of DF cells with EMAP-II knocked down by siRNA, migration indexes of bone marrow mononuclear cells were significantly reduced. These results suggest that EMAP-II is another chemotactic molecule in the dental follicle involved in recruitment of mononuclear cells, and that EMAP-II may exert its chemotactic function directly by recruiting mononuclear cells and indirectly by enhancing the expression of other chemotactic molecules (CSF-1 and MCP-1). PMID:18705801

Tooth loss in well-maintained patients with chronic periodontitis during long-term supportive therapy in Brazil.

Science.gov (United States)

Chambrone, Luiz A; Chambrone, Leandro

2006-10-01

The objective of this retrospective study was to assess the reasons for tooth loss in a sample of patients who underwent periodontal therapy and supportive periodontal therapy (SPT) in a Brazilian private periodontal practice. A sample of 120 subjects who had been treated and maintained for 10 years or longer was selected from patients attending a periodontal practice. All patients followed a similar treatment: basic procedures, re-evaluation and periodontal surgery where indicated. Reasons for tooth loss were categorized as periodontal, caries, endodontal, root fractures and extraction of retained or partially erupted third molars. Of the 2927 teeth present at the completion of active periodontal treatment, 53 (1.8%) were lost due to periodontal disease, 16 (0.5%) for root fracture, six (0.2%) to caries, five (0.2%) for endodontic reasons and 31 (1.0%) were lost to extraction of retained or partially erupted third molars. Logistic regression analysis was performed to investigate the association between five independent variables with tooth loss due to periodontitis. Only age (> 60 years) and smoking were statistically significant (p < 0.05). The findings of this survey were consistent with previous studies. Older subjects and smokers were more susceptible to periodontal tooth loss. In addition, patients with generalized chronic periodontitis were treated and maintained for long-term periods with low rates of tooth loss.

Uptake of fluoride into developing sheep teeth, following the 1995 volcanic eruption of Mt Ruapehu, New Zealand

Science.gov (United States)

Coote, G. E.; Cutress, T. W.; Suckling, G. W.

1997-07-01

In the southern Spring of 1995 (mid-October) the active volcano Mt Ruapehu in the central North Island of New Zealand erupted explosively, spreading up to 40 million m 3 of rhyolite tephra over thousands of km 2 of farmland during the lambing season. This ash contained a high concentration of soluble fluoride, and more than 2000 lactating ewes died of acute fluoride poisoning. To investigate the effects of this brief but acute dose on the teeth of grazing animals we examined the distributions of fluorine and calcium in the permanent incisor teeth of sheep which were one year old at the time. Where part of an incisor had been in the first (secretory) stage of calcification the erupted tooth disclosed surface pitting, a thin layer of enriched mineral across the enamel with as much as 1000 ppm F w/w, and a separate layer with ˜4000 ppm down the dentine. The part of an incisor which had attained the later (maturation) stage showed enriched layers only in the outer enamel and in the dentine. This study has demonstrated some important features of the calcification process, and the risk of fluoride toxicity to grazing animals.

Stem cells for tooth engineering

Directory of Open Access Journals (Sweden)

G Bluteau

2008-07-01

Full Text Available Tooth development results from sequential and reciprocal interactions between the oral epithelium and the underlying neural crest-derived mesenchyme. The generation of dental structures and/or entire teeth in the laboratory depends upon the manipulation of stem cells and requires a synergy of all cellular and molecular events that finally lead to the formation of tooth-specific hard tissues, dentin and enamel. Although mesenchymal stem cells from different origins have been extensively studied in their capacity to form dentin in vitro, information is not yet available concerning the use of epithelial stem cells. The odontogenic potential resides in the oral epithelium and thus epithelial stem cells are necessary for both the initiation of tooth formation and enamel matrix production. This review focuses on the different sources of stem cells that have been used for making teeth in vitro and their relative efficiency. Embryonic, post-natal or even adult stem cells were assessed and proved to possess an enormous regenerative potential, but their application in dental practice is still problematic and limited due to various parameters that are not yet under control such as the high risk of rejection, cell behaviour, long tooth eruption period, appropriate crown morphology and suitable colour. Nevertheless, the development of biological approaches for dental reconstruction using stem cells is promising and remains one of the greatest challenges in the dental field for the years to come.

Rates of anterior tooth wear in Middle Pleistocene hominins from Sima de los Huesos (Sierra de Atapuerca, Spain).

Science.gov (United States)

Bermúdez de Castro, J M; Martinón-Torres, M; Sarmiento, S; Lozano, M; Arsuaga, J L; Carbonell, E

2003-10-14

This study presents quantitative data on the rates of anterior tooth wear in a Pleistocene human population. The data were obtained for the hominin sample of the Sima de los Huesos site in Atapuerca, Spain. The fossil record belongs to a minimum of 28 individuals of the same biological population, assigned to the species Homo heidelbergensis. We have estimated the original and the preserved crown height of the mandibular incisors (I1 and I2) of 11 individuals, whose age at death can be ascertained from the mineralization stage and tooth eruption. Results provide a range of 0.276-0.348 and 0.288-0.360 mm per year for the mean wear rate of the mandibular I1 and I2, respectively, in individuals approximately 16-18 years old. These data suggest that incisors' crowns would be totally worn out toward the fifth decade of life. Thus, we expect the life expectancy of this population to be seriously limited. These data, which could be contrasted with results obtained on hominins at other sites, could be of interest for estimating the death age of adult individuals.

Stability of interceptive/corrective orthodontic treatment for tooth ankylosis and Class II mandibular deficiency: A case report with 10 years follow-up

Directory of Open Access Journals (Sweden)

Carlos Henrique Guimarães

2015-01-01

Full Text Available The purpose of this article is to present the treatment of a 8-year-old boy with tooth ankylosis in teeth 85 and Class II division 1 malocclusion and to report a 10-year follow-up result. The patient was initially treated with a sagittal removable appliance, followed by an eruption guidance appliance and braces. The interceptive orthodontic treatment performed to recover the space lost by ankylosis of a deciduous tooth allowed a spontaneous eruption and prevented progression of the problem. The use of an eruption-guidance appliance corrected the dentoskeletal Class II, thus improving the patient's appearance. Besides the treatment producing a good occlusal relationship with the Class I molar, the correction of the overjet and overbite was stable over a ten-year period.

External resorption presenting as an intracoronal radiolucent lesion in a pre-eruptive tooth.

LENUS (Irish Health Repository)

McNamara, C M

1997-09-01

A large intracoronal radiolucent lesion in an unerupted permanent molar was found during the routine assessment of a young male Caucasian prior to orthodontic treatment. The tooth was extracted. Histological examination indicated the lesion was caused by external resorption. The defect extended widely into the enamel and dentine, and was repaired in part by bone. The pulp chamber was not involved. The aetiology of these lesions is often obscure but in this case it appeared to have originated in the floor of two developmental pits on the occlusal surface of the tooth.

Eruption time of permanent first molars and incisors among female primary school children of riyadh

International Nuclear Information System (INIS)

Chohan, A.N.

2007-01-01

To determine the mean eruption time of permanent first molars, central and lateral incisors and to compare the relationship of mean eruption time with body mass index (BMI) in Saudi female primary school children from Riyadh, Saudi Arabia. The mean age of children was 89.3 (SD 9.6) months ranging from 71 months to 109 months. The maxillary right first molar had the lowest mean eruption time of 77.4 (SD 3.9) months and the maxillary right lateral incisor was the last tooth to erupt with eruption time of 98.4 (SD 6.5) months. Furthermore, the mandibular incisors erupted significantly earlier than maxillary incisors. By the age of 100 months, 97% of the girls had all their first permanent molars erupted. There was no significant correlation observed between eruption times with BMI of the studied teeth except the maxillary right lateral incisor. However, an inverse relationship may exist between the eruption times and BMI. The Saudi female primary school children showed later eruption time of permanent first molars, central and lateral incisors when compared with the reported results of other national studies. Key words: Eruption time, permanent teeth, Saudi Arabia, female children. (author)

Management of External Invasive Cervical Resorption Tooth with Mineral Trioxide Aggregate: A Case Report

Directory of Open Access Journals (Sweden)

Anuja Ikhar

2013-01-01

Full Text Available Invasive cervical resorption is entirely uncommon entities and the etiology is poorly understood. A 19 year old patient presented with fractured upper left central incisor and sinus tract opening on the distobuccal aspect in cervical region. Radiographic examination shows irregular radiolucency over the coronal one-third and it extended externally towards the external invasive resorption. After sectional obturation, the defect was accessed surgically. The resorption area was chemomechanically debrided using irrigant solution. Fibre post placement using flowable composite resin and Mineral Trioxide Aggregate (MTA was used to fill the resorptive defect, and the coronal access was temporarily sealed. Composite restoration was subsequently replaced with ceramic crown after 4 years. Radiographs at 1 and 4 years showed adequate repair of the resorption and endodontic success. Clinically and radiographically the tooth was asymptomatic, and no periodontal pocket was found after a 4-year followup.

Moessbauer Studies of Stannous Fluoride Reactivity with Synthetic Tooth Enamel - A Model for the Tooth Cavity Protection Actions of Novel Dentifrices

International Nuclear Information System (INIS)

Denes, Georges; Muntasar, Abdualhafeed; Kozak, Kathy M.; Baig, Arif A.; White, Donald J.

2002-01-01

SnF 2 is an important toothpaste ingredient, added for the provision of clinical efficacy for hard and soft tissue diseases and in breath protection. Synthetic calcium hydroxyapatite powders were exposed to liquid supernates (25 w/w% toothpaste water slurries, centrifuged) of Crest Gum Care (registered) (SnF 2 ) dentifrice. One-minute treatments were followed by 3x water washing, centrifugation and lyophilization. Post treatment, powders were analyzed by Moessbauer spectroscopy with 0.5-1 gram of treated apatite powder. Results show that tooth mineral stannous fluoride interactions include: (1) formation of surface reaction products with both Sn(II) and Sn(IV) oxidation states; (2) Sn-F binding on mineral surfaces with no evidence of SnO. The surface binding is, however, not pure Sn-F but contains contributions of other ligands, probably oxygens from surface phosphates or hydroxyl groups. Results also suggest that surface reacted stannous tin is oxidized with time, even when bound as a layer on the tooth surface. This study demonstrates for the first time the presence of Sn-F on tooth enamel post treatment and the contribution of passivation to long term stannous chemistry on tooth surfaces. The study also illustrates the practical applications of the Moessbauer technique.

Eruption of Odontomas into the Oral Cavity: A Report of 2 Cases

Directory of Open Access Journals (Sweden)

Sreenivasan Bhargavan Sarojini

2014-01-01

Full Text Available Odontomas are the commonest odontogenic tumors of the oral cavity and are by nature asymptomatic. They consist mainly of dental tissue that may or may not be arranged in an orderly fashion. Their presence is often detected accidentally or due to the presence of a dental disturbance such as an unerupted tooth. The very rarity of odontomas erupting into the oral cavity validates the need for more current literature on the phenomenon. Our report of two cases aims to present and discuss the rare event of an erupting odontoma with the dental community.

Doxycycline reduces the expression and activity of matrix metalloproteinase-2 in the periodontal ligament of the rat incisor without altering the eruption process.

Science.gov (United States)

Gomes, J R; Omar, N F; Neves, J D S; Novaes, P D

2017-06-01

Doxycycline is an antibiotic agent that inhibits the activity of matrix metalloproteinases (MMPs) present in the extracellular matrix. In this study, the rat incisor was submitted to a hypofunctional condition, and the effects of doxycycline (80 mg/kg/d) on the expression and activity of MMP-2, as well as on eruption rate, were determined in the odontogenic region and in the periodontal ligament for 14 d. Rats were distributed into four groups: normofunctional (NF); doxycyline normofunctional (DNF); hypofunctional (HP); and doxycyline hypofunctional (DHP). The left lower incisors of 10 rats were shortened every 2 d, using a high-rotation drill, to produce the HP and DHP groups, after starting doxycycline treatment (80 mg/kg) by gavage. Eruption was measured using a millimeter ocular, from the gingival margin to the top of the tooth in the HP and DHP groups, and also by a mark made in the tooth previously, in the NF and DNF groups. The hemimandibles were removed and the teeth were extracted to collect the periodontal and odontogenic tissues for immunohistochemical analyses and zymography. The eruption rates were higher in the HP and the DHP groups than in the NF and DNF groups, respectively (p matrix of the periodontal ligament during the tooth-eruption process. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Pre-Eruptive Coronal Resorption and Congenitally Missing Teeth in a Patient with Amelogenesis Imperfecta: A Case Report

OpenAIRE

Miloglu, Ozkan; Karaalioglu, Osman Fatih; Caglayan, Fatma; Yesil, Zeynep Duymus

2009-01-01

This clinical report describes a male with autosomal recessive generalized hypoplastic amelogenesis imperfecta. This case is unusual in coronal resorptions prior to tooth eruption. This finding has been reported in some cases of autosomal recessive, autosomal dominant and X linked amelogenesis imperfecta (AI). In reported cases, the defects were usually small and occurred in a maximum of 2 teeth per person. In our case, pre-eruptive coronal resorptions affected three second molar teeth from b...

Comparison of chronology of teeth eruption with body mass index among school children at Mangalore: A cross-sectional study

Directory of Open Access Journals (Sweden)

Nagaratna B Bagewadi

2016-01-01

Full Text Available Introduction: The development and eruption of the teeth, chronologies of human dentitions, dental age, and tooth formation standards are important aspects applied to dental practice. Body mass index (BMI gives an indication about the nutritional status of the child. It is relevant to know whether BMI has influenced chronology of tooth eruption pattern. Aim: To determine the eruption age of the different permanent teeth and compare eruption age with BMI in a group of children from selected schools in Mangalore. Materials and Methods: A cross-sectional study was designed in which 2928 children ranging in age from 5.5 to 15 years were included in the study. The children were divided into 20 chronological age groups with half year intervals. All the children were examined by a single examiner with the help of a trained assistant. The teeth were examined under natural light with mouth mirror. The comparison was made between mean eruption ages in males and females using the independent t-test. Results: There were 1526 males constituting 52.1% and 1402 females constituting 47.9% of the total sample of 2928 children. The mean age of eruption of maxillary central incisor, maxillary lateral incisor, maxillary and mandibular canines, maxillary and mandibular premolars, maxillary and mandibular second molars were found to have statistical significant with BMI. The mean age of eruption of the teeth in females was found to be earlier than in males, with the exception of the maxillary first molar which is earlier in males. Conclusion: Different categories of BMI were underweight, normal weight, risk of overweight and overweight, wherein overweight children had early eruption of teeth. Girls had early eruption time compared to boys.

Reducing Early Childhood Tooth Decay: Strategies for State Medicaid and CHIP Dental Program Managers

OpenAIRE

Colin Reusch; Meg Booth; Leslie Foster

2015-01-01

Young children who are enrolled in Medicaid or the Children’s Health Insurance Program (CHIP) can be at risk for developing early childhood caries (ECC). ECC is a chronic bacterial infection that causes severe tooth decay and can begin to develop before baby teeth erupt.

Age-related changes in the tooth-bone interface area of acrodont dentition in the chameleon.

Science.gov (United States)

Dosedělová, Hana; Štěpánková, Kateřina; Zikmund, Tomáš; Lesot, Herve; Kaiser, Jozef; Novotný, Karel; Štembírek, Jan; Knotek, Zdeněk; Zahradníček, Oldřich; Buchtová, Marcela

2016-09-01

Chameleon teeth develop as individual structures at a distance from the developing jaw bone during the pre-hatching period and also partially during the post-hatching period. However, in the adult, all teeth are fused together and tightly attached to the jaw bone by mineralized attachment tissue to form one functional unit. Tooth to bone as well as tooth to tooth attachments are so firm that if injury to the oral cavity occurs, several neighbouring teeth and pieces of jaw can be broken off. We analysed age-related changes in chameleon acrodont dentition, where ankylosis represents a physiological condition, whereas in mammals, ankylosis only occurs in a pathological context. The changes in hard-tissue morphology and mineral composition leading to this fusion were analysed. For this purpose, the lower jaws of chameleons were investigated using X-ray micro-computed tomography, laser-induced breakdown spectroscopy and microprobe analysis. For a long time, the dental pulp cavity remained connected with neighbouring teeth and also to the underlying bone marrow cavity. Then, a progressive filling of the dental pulp cavity by a mineralized matrix occurred, and a complex network of non-mineralized channels remained. The size of these unmineralized channels progressively decreased until they completely disappeared, and the dental pulp cavity was filled by a mineralized matrix over time. Moreover, the distribution of calcium, phosphorus and magnesium showed distinct patterns in the different regions of the tooth-bone interface, with a significant progression of mineralization in dentin as well as in the supporting bone. In conclusion, tooth-bone fusion in chameleons results from an enhanced production of mineralized tissue during post-hatching development. Uncovering the developmental processes underlying these outcomes and performing comparative studies is necessary to better understand physiological ankylosis; for that purpose, the chameleon can serve as a useful model

Metabolism in tooth enamel and reliability of retrospective EPR dosimetry connected with Chernobyl accident

International Nuclear Information System (INIS)

Brik, A.; Radchuk, V.; Scherbina, O.; Matyash, M.; Gaver, O.

1996-01-01

It is shown that the results of retrospective EPR dosimetry by tooth enamel are essentially determined by the fact that tooth enamel is the mineral of biological origin. The structure of tooth enamel, properties of radiation defects and the role of metabolism in tooth enamel are discussed. It is shown that at deep metamorphic modifications tooth enamel don't save information about its radiation history. The reliability and accuracy of retrospective EPR dosimetry are discussed. Because after Chernobyl accident have passed 10 years the application of tooth enamel for reconstruction of doses which are connected with Chernobyl accident need care and additional investigations

The chronology and sequence of eruption of human permanent teeth in Northern Ireland.

Science.gov (United States)

Kochhar, R; Richardson, A

1998-12-01

To ascertain the average and range of ages and sequence of eruption of human permanent teeth, taking into account the effect of premature loss of primary antecedents. Longitudinal study. Caucasian subjects in Northern Ireland. Study casts at 6-monthly intervals from age 5 to 15 years of 276 children (146 males and 130 females) enrolled in the Belfast Growth Study. The mean and range of ages of eruption of each individual tooth were computed. Comparisons were made between the mean ages of eruption with and without premature loss of primary antecedents, between upper and lower arches, between right and left sides and between males and females. The sequence of eruption was also investigated. The means and ranges of eruption ages are reported. Premature loss of primary antecedents delayed eruption of permanent successors except for the upper premolars which were accelerated. The differences relating to the upper first premolar and lower canine were not statistically significant. Each lower tooth erupted before its upper counterpart except for the premolars. There was no significant difference in age of eruption between right and left sides. Females tended to erupt teeth before males with the exception of the second molars in both arches; however, the only differences to reach statistical significance related to upper and lower canines and upper lateral incisors. The most frequent orders of eruption were unique to the subject. These occurred in 22% of upper and 33% of lower arches. The classic sequences: first molar-central incisor-lateral incisor-first premolar-canine-second premolar-second molar (M1-I1-I2-PM1-C-PM2-M2) in the upper arch and I1-M1-I2-C-PM1-PM2-M2 in the lower arch occurred in only 16% of upper arches and 13% of lower arches. Males adhered to the textbook sequence (20% upper, 17% lower) more than females (12% upper, 8% lower). In the upper arch of females, the order M1-I1-I2-PM1-PM2-C-M2 in 10% of subjects was almost as frequent as the classic sequence

Relationship between mineral distributions in dentine lesions and subsequent remineralization in vitro

NARCIS (Netherlands)

Kawasaki, K; Ruben, J; Tsuda, H; Huysmans, MCDNJM; Takagi, O

2000-01-01

Though the mineral distribution of the dentine carious lesion varies largely from tooth to tooth and from patient to patient, there are two main distribution profiles that characterize natural carious lesions in dentine. These profiles include softened and subsurface lesion types. The mineral

Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.

Science.gov (United States)

Tanaka, Reina; Shibata, Yo; Manabe, Atsufumi; Miyazaki, Takashi

2010-04-01

Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.

Determination of permanent premolars eruption ages among public school children in Lahore, Pakistan

International Nuclear Information System (INIS)

Jokhio, A.L.; Soomro, S.H.; Khuhawar, S.R.

2015-01-01

Objective: To determine mean eruption age, range and sequence of permanent maxillary and mandibular premolars in public schools of Lahore, Pakistan so as to provide a reference for planning orthodontic treatment and in pediatric dentistry. Methodology: This is a cross sectional study consisting of multistage random sampling and included 4000 children, with ages in between 9-14 years of different public schools in Lahore. Participants were examined and tooth numbering was noted by two-digit system of FDI (Federation Dentaire Internationale). Emergence was divided into three stages depending on eruption level. SPSS version 18 was used for statistical analysis. Results: Out of 4000 children, 1960 were boys and 2031 were girls. In both genders maxillary premolars erupted before mandibular counterparts. All premolars erupted earlier in females than the males. The sequence of emergence for both genders was P1, P2 in upper as well as in lower arch. Conclusion: Eruption of premolar in females was earlier than males but delayed in both genders while compared with Western standard. (author)

Predicting lower third molar eruption on panoramic radiographs after cephalometric comparison of profile and panoramic radiographs

DEFF Research Database (Denmark)

Begtrup, Anders; Grønastøð, Halldis Á; Christensen, Ib Jarle

2012-01-01

and to find a simple and reliable method for predicting the eruption of the mandibular third molar by measurements on panoramic radiographs. The material consisted of profile and panoramic radiographs, taken before orthodontic treatment, of 30 males and 23 females (median age 22, range 18-48 years......Previous studies have suggested methods for predicting third molar tooth eruption radiographically. Still, this prediction is associated with uncertainty. The aim of the present study was to elucidate the association between cephalometric measurements on profile and panoramic radiographs...... the length from the ramus to the incisors (olr-id) showed a statistically significant correlation. By combining this length with the mesiodistal width of the lower second molar, the prediction of eruption of the lower third molar was strengthened. A new formula for calculating the probability of eruption...

The investigation of usage of fluorapatite mineral (Ca{sub 5}F(PO{sub 4}){sub 3}) in tooth enamel under the different pre-irradiation thermal treatments

Energy Technology Data Exchange (ETDEWEB)

Toktamiş, Hüseyin, E-mail: toktamis@gantep.edu.tr [University of Gaziantep, Department of Engineering Physics, 27310 Gaziantep (Turkey); Toktamiş, Dilek; Yilmaz, S. Merve; Yazici, A. Necmeddin [University of Gaziantep, Department of Engineering Physics, 27310 Gaziantep (Turkey); Yildirim, Cihan [University of Gaziantep, Faculty of Dentistry, 27310 Gaziantep (Turkey); Özbiçki, Özlem [Dentalazer Hospital, 27310 Gaziantep (Turkey)

2015-01-20

Highlights: • The fluorapatite mineral extracted from tooth enamel shows TL properties. • The pre-irradiation annealing process affects the TL glow curve shape. • A huge increase was observed in maximum TL for sample annealed at 1100 °C. • Annealing about 120 min causes a huge enhancement in maximum TL peak intensity • The best reproducibility is obtained at 1000 °C of annealing temperature. - Abstract: Fluorapatite Ca{sub 5}F(PO{sub 4}){sub 3} is a kind of important thermoluminescence dosimeter (TLD) material, because the effective atomic number of fluorapatite is close to that of human bones and teeth. In the present study, thermoluminescence (TL) properties of fluorapatite mineral in tooth enamel under the different annealing temperatures with various annealing times were investigated. This study reveals that the fluorapatite in tooth enamel exhibits TL properties. Annealing of the sample affects extremely the TL glow curve and causes a huge enhancement in the sensitization of TL peak. The sample annealed at 1000 °C about 120 min gives best TL peak intensity (150 factors than un-annealed sample) and has a distinct peak around 230 °C. Also, the best reproducibility was observed for 1000 °C annealed sample temperature while un-annealed sample shows the worst reproducibility. Moreover, a good linearity in dose response is observed in the samples annealed at 400 °C and 700 °C.

Witkop′s tooth and nail syndrome: A multifaceted approach to dental management

Directory of Open Access Journals (Sweden)

Subramaniam P

2008-03-01

Full Text Available Witkop′s tooth and nail syndrome is a rare autosomal dominant disorder of ectodermal dysplasia characterized by hypodontia and nail dysplasia. Mutations in MSX-1 have been shown to be associated with this syndrome. There is failure of development and eruption of the dentition. Tooth shape may vary; the most common forms are conical and narrow crowns. The nails may be spoon shaped and slow growing and affect both finger and toe nails. The nail involvement is more severe in childhood. The present case describes a 14-year-old boy who showed the characteristic features of Witkop′s syndrome. A multifaceted approach to the dental management of the patient is discussed.

The cell biology and role of resorptive cells in diseases: A review.

Science.gov (United States)

Babaji, Prashant; Devanna, Raghu; Jagtap, Kiran; Chaurasia, Vishwajit Rampratap; Jerry, Jeethu John; Choudhury, Basanta Kumar; Duhan, Dinesh

2017-01-01

Resorptive cells are responsible for the resorption of mineralized matrix of hard tissues. Bone-resorbing cells are called osteoclasts; however, they can resorb mineralized dental tissues or calcified cartilage and then they are called odontoclasts and chondroclasts, respectively. Resorptive cells form when mononuclear precursors derived from a monocyte-macrophage cell lineage are attracted to certain mineralized surfaces and subsequently fuse and adhere onto them for exerting their resorbing activity. These cells are responsible for degradation of calcified extracellular matrix composed of organic molecules and hydroxyapatite. The activity of these cells can be observed in both physiological and pathological processes throughout life and their activity is mainly required in bone turnover and growth, spontaneous and induced (orthodontic) tooth movement, tooth eruption, and bone fracture healing, as well as in pathological conditions such as osteoporosis, osteoarthritis, and bone metastasis. In addition, they are responsible for daily control of calcium homeostasis. Clastic cells also resorb the primary teeth for shedding before the permanent teeth erupt into the oral cavity.

Assisted eruption of impacted teeth into an alveolar bone graft in a patient with cleft lip and palate.

Science.gov (United States)

Peamkaroonrath, Chonthicha; Manosudprasit, Montien; Godfrey, Keith

2008-11-01

To assist the eruption of impacted upper teeth into an alveolar bone graft in a patient with a unilateral cleft lip and palate. An 8-year-old Thai boy with left unilateral complete cleft lip and palate had the chief complaint of anterior crossbite. He presented with a mild skeletal 3, dental Class III subdivision malocclusion, anterior crossbite, left unilateral posterior crossbite, moderate crowding in the upper arch with impaction of upper the left lateral incisor (tooth 22) and canine (tooth 23). In the first phase of treatment the posterior crossbite was corrected with a removable appliance with a 3-way screw. In the second phase the impacted teeth were surgically exposed, moved into the alveolar bone graft and the teeth aligned with fixed appliances. The upper left lateral incisor was extracted because of its questionable longevity. The orthodontic treatment resulted in normal overjet, overbite and an acceptable facial profile. A prosthesis replaced tooth 22. Forced eruption of impacted teeth can be carried out successfully in the cleft patients after an appropriate treatment plan has been formulated and following preparation of alveolar bone graft in the cleft site.

The role of polymorphisms associated with early tooth eruption in dental and occlusal traits in East Asian populations

Science.gov (United States)

Kawaguchi, Akira; Kim, Yong-Il; Haga, Shugo; Katayama, Koshu; Ishida, Hajime; Park, Soo-Byung; Maki, Koutaro; Kimura, Ryosuke

2014-01-01

Objective A recent study suggested that rs6504340, a polymorphism within the homeobox B (HOXB) gene cluster, is associated with the susceptibility for malocclusions in Europeans. The resulting malocclusions require orthodontic treatment. The aim of this study was to investigate the association of rs6504340 and other dentition-implicated polymorphisms with dental and occlusal traits in Korean and Japanese populations. Methods The study participants included 223 unrelated Koreans from the Busan area and 256 unrelated Japanese individuals from the Tokyo metropolitan area. DNA samples were extracted from saliva specimens. Genotyping for rs6504340 and four single nucleotide polymorphisms (SNPs) that have been shown to be associated with the timing of first tooth eruption and the number of teeth at 1 year of age (rs10506525, rs1956529, rs9674544, and rs8079702) was performed using TaqMan assays. The Index of Orthodontic Treatment Need (IOTN), overjet, overbite, arch length discrepancy, crown sizes, and length and width of the dental arches were measured. Spearman's correlation coefficients were calculated to evaluate relationships between rs6504340 and these dental/occlusal traits. Results We evaluated the aesthetic components and dental health components of the IOTN in the Korean and Japanese populations and found that neither rs6504340 nor the other four SNPs showed any association with dental and occlusal traits in these East Asian populations. Conclusions These negative results suggest that further research is needed to identify the genetic determinants of malocclusions in order to reach a consensus. PMID:24696826

Interdisciplinary Studies of Eruption at Chaitén Volcano, Chile

Science.gov (United States)

Pallister, John S.; Major, Jon J.; Pierson, Thomas C.; Hoblitt, Richard P.; Lowenstern, Jacob B.; Eichelberger, John C.; Lara, Luis; Moreno, Hugo; Muñoz, Jorge; Castro, Jonathan M.; Iroumé, Andrés; Andreoli, Andrea; Jones, Julia; Swanson, Fred; Crisafulli, Charlie

2010-10-01

High-silica rhyolite magma fuels Earth's largest and most explosive eruptions. Recurrence intervals for such highly explosive eruptions are in the 100- to 100,000­year time range, and there have been few direct observations of such eruptions and their immediate impacts. Consequently, there was keen interest within the volcanology community when the first large eruption of high-silica rhyolite since that of Alaska's Novarupta volcano in 1912 began on 1 May 2008 at Chaitén volcano, southern Chile, a 3-kilometer­diameter caldera volcano with a prehistoric record of rhyolite eruptions [Naranjo and Stern, 2004; Servicio Nacional de Geología y Minería (SERNAGEOMIN), 2008; Carn et al., 2009; Castro and Dingwell, 2009; Lara, 2009; Muñoz et al., 2009]. Vigorous explosions occurred through 8 May 2008, after which explosive activity waned and a new lava dome was extruded.

Using Spectroscopy to Infer the Eruption Style and Volatile History of Volcanic Tephras

Science.gov (United States)

McBride, M. J.; Horgan, B. H. N.; Rowe, M. C.; Wall, K. T.; Oxley, B. M.

2017-12-01

The interaction between volatiles and magma strongly influences volcanic eruption styles, and results in an increase in the glass component of volcanic tephra. On Earth, both phreatomagmatic and magmatic explosive eruptions create glassy tephras. Phreatomagmatic eruptions form abundant glass by quickly quenching lava through interaction with meteoric water while magmatic eruptions create less glass through slower cooling within larger pyroclasts or eruption columns. Wall et al. (2014) used X-ray diffraction (XRD) of diverse tephra samples to show that glass content correlates with eruption style, as magmatic samples contain less glass than phreatomagmatic samples. While use of XRD is limited to Earth and the Curiosity rover on Mars, orbital spectroscopy is much a more common technique in the exploration of terrestrial bodies. In this study, we evaluate whether or not spectroscopy can be used to infer eruption style and thus volatile history. Visible/near-infrared (VNIR) and thermal-infrared (TIR) spectra were collected of the Wall et al. (2014) tephra samples, and were analyzed for trends related to glass content and thus eruption style. VNIR spectra can detect glass at high abundances as well as hydrothermal alteration minerals produced during interactions with meteoric water. Using TIR, glass abundances can be derived by deconvolving the spectra with a standard spectral library; however, due to the non-unique spectral shape of glass, intermediate to high glass abundances in tephras are difficult to differentiate using TIR alone. Synthetic mixtures of glass and crystalline minerals verify these results. Therefore, the most effective method for determining glass abundance and thus eruption style from volcanic deposits is a combination of VNIR and TIR spectral analysis. Using standard planetary remote sensing instrumentation to infer eruption styles will provide a new window into the volcanic and volatile histories of terrestrial bodies.

Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics.

Science.gov (United States)

Petrone, Chiara Maria; Bugatti, Giuseppe; Braschi, Eleonora; Tommasini, Simone

2016-10-05

Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occurrence of substantial temperature differences within magma chambers, which often bias the estimated timescales in the case of multi-stage zoned minerals. Here we propose a new Non-Isothermal Diffusion Incremental Step model to take into account the non-isothermal nature of pre-eruptive processes, deconstructing the main core-rim diffusion profiles of multi-zoned crystals into different isothermal steps. The Non-Isothermal Diffusion Incremental Step model represents a significant improvement in the reconstruction of crystal lifetime histories. Unravelling stepwise timescales at contrasting temperatures provides a novel approach to constraining pre-eruptive magmatic processes and greatly increases our understanding of magma chamber dynamics.

Geographic Variations in the EPR Spectrum of Tooth Enamel

International Nuclear Information System (INIS)

Romanyukha, A.A.; Hayes, R.B.; Haskell, E.H.; Kenner, G.H.

1999-01-01

The presence of stable radiation-induced radicals in the mineral component of tooth enamel allows use of this material as a biological dosemeter. Estimation of the dose absorbed in tooth enamel can be done by EPR. Generally, for the purpose of dose reconstruction, the EPR spectrum of tooth enamel is interpreted in terms of two main components. The first is a broad background signal often called the native signal centered at a g value of 2.0045. The origin of this signal is not precisely known. The second main component in the tooth enamel spectrum is purely radiation induced and can be used for retrospective dosimetry. Internal structure of the native signal and variations of its amplitude and linewidth were investigated for the samples prepared from modern teeth obtained from different geographic locations (USA and Russia). Possible reasons for the variations observed are discussed as are the potential effects of the variations on the reliability of dose estimation. (author)

Unusual intraosseous transmigration of impacted tooth

Energy Technology Data Exchange (ETDEWEB)

Kumar, Santosh; Urala, Arun Srinivas; Kamath, Abhay Taranath; Jayaswal, Priyanka; Valiathan, Ashima [Manipal College of Dental Sciences, Manipal (India)

2012-03-15

Transmigration of an impacted tooth through the symphyseal suture is a rare and special developmental anomaly of unknown etiology that is unique to the mandibular canine. Maxillary canine transmigration is even rarer. Transmigrated canines are particularly significant due to the aesthetic and functional importance. A maxillary lateral incisor crossing the mid-palatal suture has never been reported in the literature. The aim of this report is to present the first case of simultaneous transmigration of a lateral incisor and canine in the maxilla. The paper also reports four unusual cases of unilateral canine transmigration in the maxilla and mandible and successful eruption of one of the transmigrated mandibular canines following orthodontic traction. Etiology of transmigration and its clinical considerations are also discussed.

Unusual intraosseous transmigration of impacted tooth

International Nuclear Information System (INIS)

Kumar, Santosh; Urala, Arun Srinivas; Kamath, Abhay Taranath; Jayaswal, Priyanka; Valiathan, Ashima

2012-01-01

Transmigration of an impacted tooth through the symphyseal suture is a rare and special developmental anomaly of unknown etiology that is unique to the mandibular canine. Maxillary canine transmigration is even rarer. Transmigrated canines are particularly significant due to the aesthetic and functional importance. A maxillary lateral incisor crossing the mid-palatal suture has never been reported in the literature. The aim of this report is to present the first case of simultaneous transmigration of a lateral incisor and canine in the maxilla. The paper also reports four unusual cases of unilateral canine transmigration in the maxilla and mandible and successful eruption of one of the transmigrated mandibular canines following orthodontic traction. Etiology of transmigration and its clinical considerations are also discussed.

An erupted odontoma associated with pigmentation: A histogenetic and histological perspective

Directory of Open Access Journals (Sweden)

Gurkiran A Kaur

2012-01-01

Full Text Available Odontomas are hamartomatous malformations of odontogenic origin composed of all the structures that form the tooth. Pigmentation associated with odontomas is rare, with only two cases reported in the literature. The genesis of this composite malformation is attributable to the organizational failure of the developing odontogenic apparatus leading to abnormal morphodifferentiation. Although some odontomas erupt into the oral cavity, it defies the existing views of normal physiologic tooth movement thus raising questions over the use of this term. Here, we review a case of large odontoma in a 23-year-old male surfacing into the oral cavity from its intraosseous location. The unusual occurrence of melanotic pigmentation in the odontogenic epithelial rests was demonstrated by Mason Fontana special stain. The histogenesis of this unusual entity and explanation to its possible occurrence is discussed.

Fragile X syndrome: panoramic radiographic evaluation of dental anomalies, dental mineralization stage, and mandibular angle.

Science.gov (United States)

Sabbagh-Haddad, Aida; Haddad, Denise Sabbagh; Michel-Crosato, Edgard; Arita, Emiko Saito

2016-01-01

The purpose of this study was to evaluate the dental radiographic characteristics as described in 40 records of patients with panoramic radiography. The patients were in the range of 6-17 years old, and were divided into two groups (20 subjects who were compatible with the normality standard and 20 individuals diagnosed with the FXS), which were matched for gender and age. Analysis of the panoramic radiographic examination involved the evaluation of dental mineralization stage, mandibular angle size, and presence of dental anomalies in both deciduous and permanent dentitions. The results of radiographic evaluation demonstrated that the chronology of tooth eruption of all third and second lower molars is anticipated in individuals with FXS (pdental anomalies. In addition, an increase was observed in the mandibular angle size in the FXS group (pdental radiographic changes is of great importance for dental surgeons to plan the treatment of these individuals.

Permanent maxillary canines - review of eruption pattern and local etiological factors leading to impaction.

Science.gov (United States)

Sajnani, Anand K

2015-02-01

The position of the permanent maxillary canine at the angle of the mouth is strategically significant in maintaining the harmony and symmetry of the occlusal relationship. However, the maxillary canine is the second most frequently impacted tooth, with prevalence reported to be between 1% and 2%. Moreover, treatment of this condition is often complex and involves substantial time and financial cost. Hence, it is only prudent to monitor the eruption and identify the etiological factors that lead to impaction of the maxillary canine. Numerous researchers have tried to identify specific and nonspecific etiological factors responsible for displacement of canines. The purpose of this review was to track the development processes of maxillary canines and determine the hindrances that affect the eruption at different ages. Awareness of the eruption process and etiology of noneruption will help to reduce the incidence of impacted canines by allowing for early recognition and interceptive treatment. © 2013 Wiley Publishing Asia Pty Ltd.

Fumarolic minerals

DEFF Research Database (Denmark)

Balic Zunic, Tonci; Garavelli, Anna; Jakobsson, Sveinn Peter

2016-01-01

The fumarolic mineralogy of the Icelandic active volcanoes, the Tyrrhenian volcanic belt (Italy) and the Aegean active arc (Greece) is investigated, and literature data surveyed in order to define the characteristics of the European fumarolic systems. They show broad diversity of mineral...... associations, with Vesuvius and Vulcano being also among the world localities richest in mineral species. Volcanic systems, which show recession over a longer period, show fumarolic development from the hightemperature alkaline halide/sulphate, calcic sulphate or sulphidic parageneses, synchronous...... with or immediately following the eruptions, through mediumtemperature ammonium minerals, metal chlorides, or fluoride associations to the late low-temperature paragenesis dominated by sulphur, gypsum, alunogen, and other hydrous sulphates. The situation can be different in the systems that are not recessing but show...

Apical Revascularization after Delayed Tooth Replantation: An Unusual Case

Directory of Open Access Journals (Sweden)

Marília Pacífico Lucisano

2016-01-01

Full Text Available The aim of this paper is to present the clinical and radiological outcome of the treatment involving a delayed tooth replantation after an avulsed immature permanent incisor, with a follow-up of 1 year and 6 months. An 8-year-old boy was referred after dental trauma that occurred on the previous day. The permanent maxillary right central incisor (tooth 11 had been avulsed. The tooth was hand-held during endodontic therapy and an intracanal medication application with calcium hydroxide-based paste was performed. An apical plug with mineral trioxide aggregate (MTA was introduced into the apical portion of the canal. When the avulsed tooth was replanted with digital pressure, a blood clot had formed within the socket, which moved the MTA apical plug about 2 mm inside of the root canal. These procedures developed apical revascularization, which promoted a successful endodontic outcome, evidenced by apical closure, slight increase in root length, and absence of signs of external root resorption, during a follow-up of 1 year and 6 months.

Storage, Ascent, and Release of Silicic Magma in Caldera-forming Eruptions

Science.gov (United States)

Myers, Madison Logan

The mechanisms and timescales associated with the triggering of caldera-forming eruptions remain ambiguous and poorly constrained. Do such eruptions start vigorously, then escalate, or can there be episodicity? Are they triggered through internal processes (e.g. recharge, buoyancy), or can external modulations play an important role? Key to answering these questions is the ability to reconstruct the state of the magma body immediately prior to eruption. My dissertation research seeks to answer these questions through detailed investigation of four voluminous caldera-forming eruptions: (1) 650 km3, 0.767 Ma Bishop Tuff, Long Valley, (2) 530 km3, 25.4 ka Oruanui eruption, Taupo, (3) 2,500 km3, 2.08 Ma Huckleberry Ridge Tuff, Yellowstone and (4) 250 km3, 26.91 Ma Cebolla Creek Tuff, Colorado. The main techniques I applied integrated glass geochemistry (major, trace and volatile), diffusion modeling, and detailed field sampling. In chapters two, three, and four these methods are applied to the initial fall deposits of three supereruptions (Bishop, Oruanui and Huckleberry Ridge) that preserve field-evidence for different opening behaviors. These behaviors range from continuous deposition of fall deposits and ignimbrite (Bishop), to repetitive start/stop behavior, with time breaks between eruptive episodes on the order of weeks to months (Oruanui, Huckleberry Ridge). To reconstruct the timescales of opening activity and relate this to conduit processes, I used two methods that exploit diffusion of volatiles through minerals and melt, providing estimates for the rate at which magmas ascended to the surface. This knowledge is then integrated with the pre-eruptive configuration of the magma body, based on melt inclusion chemistry, to interpret what triggered these systems into unrest. Finally, in chapter five I take a different approach by integrating geochemical data for melt inclusions and phenocryst minerals to test whether the mechanism of heat and volatile recharge

Altered Passive Eruption Complicating Optimal Orthodontic Bracket Placement: A Case Report and Review of Literature.

Science.gov (United States)

Pulgaonkar, Rohan; Chitra, Prasad

2015-11-01

An unusual case of altered passive eruption with gingival hyperpigmentation and a Class I malocclusion in a 12-year-old girl having no previous history of medication is presented. The patient reported with spacing in the upper arch, moderate crowding in the lower arch, anterior crossbite and excessive gingival tissue on the labial surfaces of teeth in both the arches. The inadequate crown lengths made placement of the orthodontic brackets difficult. Preadjusted orthodontic brackets have a very precise placement protocol which can affect tooth movement in all 3 planes of space if violated. The periodontal condition was diagnosed as altered passive eruption Type IA. Interdisciplinary treatment protocols including periodontal surgical and orthodontic procedures were used. The periodontal surgical procedures were carried out prior to orthodontic therapy and the results obtained were satisfactory. It is suggested that orthodontists should be aware of conditions like altered passive eruption and modalities of management. In most instances, orthodontic therapy is not hindered.

Disturbed tooth formation by 60Co-gamma-ray radiation

International Nuclear Information System (INIS)

Doh, Akio

1982-01-01

The molar of guinea pigs was irradiated with 60 Co-#betta# ray for daily observations of the manifestation of disturbed tooth formation by microradiography and the time registration by tetracycline-labelling. Irradiation first injured young blast cells of the dentin in the growth phase, dental pulp cells, and cells of the enamel. The portion composed of injured cells formed a depressed ''constriction'' from the dental pulp side toward the border between the enamel and dentin. The cells of the enamel injured by irradiation in the growth phase later formed a very thin irregular stroma. In contrast, cells in the differentiation or subsequent phase at the time of irradiation and cells probably having started to grow after irradiation proceeded with formation of a normal stroma and calcification. No uniform relation was obtained between the histological staining of the organic stroma of normal or abnormal dentin and calcification. Labelling with tetracycline revealed that the irradiation conditions in the present study provoked hardly any changes in the speed of tooth eruption. (Chiba, N.)

In-depth, high-accuracy proteomics of sea urchin tooth organic matrix

Directory of Open Access Journals (Sweden)

Mann Matthias

2008-12-01

Full Text Available Abstract Background The organic matrix contained in biominerals plays an important role in regulating mineralization and in determining biomineral properties. However, most components of biomineral matrices remain unknown at present. In sea urchin tooth, which is an important model for developmental biology and biomineralization, only few matrix components have been identified. The recent publication of the Strongylocentrotus purpuratus genome sequence rendered possible not only the identification of genes potentially coding for matrix proteins, but also the direct identification of proteins contained in matrices of skeletal elements by in-depth, high-accuracy proteomic analysis. Results We identified 138 proteins in the matrix of tooth powder. Only 56 of these proteins were previously identified in the matrices of test (shell and spine. Among the novel components was an interesting group of five proteins containing alanine- and proline-rich neutral or basic motifs separated by acidic glycine-rich motifs. In addition, four of the five proteins contained either one or two predicted Kazal protease inhibitor domains. The major components of tooth matrix were however largely identical to the set of spicule matrix proteins and MSP130-related proteins identified in test (shell and spine matrix. Comparison of the matrices of crushed teeth to intact teeth revealed a marked dilution of known intracrystalline matrix proteins and a concomitant increase in some intracellular proteins. Conclusion This report presents the most comprehensive list of sea urchin tooth matrix proteins available at present. The complex mixture of proteins identified may reflect many different aspects of the mineralization process. A comparison between intact tooth matrix, presumably containing odontoblast remnants, and crushed tooth matrix served to differentiate between matrix components and possible contributions of cellular remnants. Because LC-MS/MS-based methods directly

Platelet-rich fibrin-mediated revitalization of immature necrotic tooth

Directory of Open Access Journals (Sweden)

Navin Mishra

2013-01-01

Full Text Available Contemporary studies have shown that the regeneration of tissues and root elongation is possible in necrotic immature permanent teeth. The purpose of this case report is to add a new vista in regenerative endodontic therapy by using platelet rich fibrin for revitalization of immature non vital tooth. An 11year old boy with the history of trauma was diagnosed with the pulpal necrosis and symptomatic apical periodontitis in tooth #21. Intra oral periapical radiograph showed open apex and associated immature supernumerary tooth with respect to tooth #21. Access preparation and minimal instrumentation was done to remove necrotic debris under copious irrigation with 2.5% sodium hypochlorite. Triple antibiotic paste was packed in the canal for four weeks. During second visit, 5 mL of whole blood was drawn from the medial cubital vein of the patient and blood was then subjected to centrifugation at 2400 rpm for 12 minutes for the preparation of Platelet rich fibrin (PRF utilizing Choukroun′s method. Triple antibiotic paste was removed and canal was dried. PRF clot was pushed to the apical region of tooth #21 using hand pluggers. Three milimetres of Mineral trioxide (MTA was placed in cervical part of the root canal and permanent restoration was done three days later. Clinical examination at 6 and 12 months revealed no sensitivity to percussion and palpation in tooth #21and it responded positively to both electric pulp and cold tests. Radiographic examination showed resolution of periapical rarefaction, further root development and apical closure of the tooth #21 and its associated supernumerary tooth. On the basis of successful outcome of the present case it can be stated that PRF clot may serve as a scaffold for regeneration of necrotic immature teeth.

Sequences and timing of dental eruption in semi-free-ranging mandrills (Mandrillus sphinx).

Science.gov (United States)

Setchell, Joanna M; Wickings, E Jean

2004-01-01

The chronology of tooth emergence is often used to examine the growth and development of individuals and to compare life histories across species. Emergence patterns are also used to age animals and to infer life history influences for extinct species. However, comparative studies of primates are hindered by a lack of dental development data for many species. Here we describe the sequences and timing of tooth emergence for a large sample of semi-free-ranging mandrills (Mandrillus sphinx) and compare this with other life history variables for this species. Deciduous dentition emerged in the sequence i1 i2 c p3 p4. The augmented sequence (including information about variability in emergence sequence) was i1 i2 [c p3] p4 for the female maxilla and the male mandible, and i1 i2 c p3 p4 for the female mandible and the male maxilla. Deciduous dentition was complete by 5.0 months in females and 6.4 months in males. The permanent dentition began to emerge at 26 months, and complete adult dentition had emerged by 68 months for males and 85 months for females. Sex differences occurred in the augmented eruption sequences: females M1 I1 I2 [M2 C] P3 P4 M3, males M1 I1 [I2 M2] [P4 = P3 = C] M3. The order of tooth eruption and the occurrence of sequence polymorphisms were very similar to those observed for baboons and macaques. Comparison with life history variables showed that mandrills have complete deciduous dentition at weaning, females possess both adult incisors and M1 when they first reproduce, but still have deciduous canines and premolars, and that both sexes have full adult dentition before they attain their full adult stature and mass.

Monte Carlo modeling of human tooth optical coherence tomography imaging

International Nuclear Information System (INIS)

Shi, Boya; Meng, Zhuo; Wang, Longzhi; Liu, Tiegen

2013-01-01

We present a Monte Carlo model for optical coherence tomography (OCT) imaging of human tooth. The model is implemented by combining the simulation of a Gaussian beam with simulation for photon propagation in a two-layer human tooth model with non-parallel surfaces through a Monte Carlo method. The geometry and the optical parameters of the human tooth model are chosen on the basis of the experimental OCT images. The results show that the simulated OCT images are qualitatively consistent with the experimental ones. Using the model, we demonstrate the following: firstly, two types of photons contribute to the information of morphological features and noise in the OCT image of a human tooth, respectively. Secondly, the critical imaging depth of the tooth model is obtained, and it is found to decrease significantly with increasing mineral loss, simulated as different enamel scattering coefficients. Finally, the best focus position is located below and close to the dental surface by analysis of the effect of focus positions on the OCT signal and critical imaging depth. We anticipate that this modeling will become a powerful and accurate tool for a preliminary numerical study of the OCT technique on diseases of dental hard tissue in human teeth. (paper)

Regional early development and eruption of permanent teeth: case report.

Science.gov (United States)

Al Mullahi, A M; Bakathir, A; Al Jahdhami, S

2017-02-01

Early development and eruption of permanent teeth are rarely reported in scientific literature. Early eruption of permanent teeth has been reported to occur due to local factors such as trauma or dental abscesses in primary teeth, and in systemic conditions. Congenital diffuse infiltrating facial lipomatosis (CDIFL) is a rare condition that belongs to a group of lipomatosis tumours. In this disorder, the mature adipocytes invade adjacent soft and hard tissues in the facial region. Accelerated tooth eruption is one of the dental anomalies associated with CDIFL. A 3-year-old boy presented with a swelling of the lower lip localised early development and eruption of permanent teeth and dental caries involving many primary teeth. The planned treatment included biopsy of the swollen lower lip to confirm the diagnosis, surgical reduction and reconstruction of lip aesthetics. The management of the carious primary teeth included preventative and comprehensive dental care and extractions. These procedures were completed under general anaesthesia due to the child's young age and poor cooperation. The lip biopsy showed features of CDIFL such as the presence of infiltrating adipose tissue, prominent number of nerve bundles and thickened vessels. The high recurrence rate of CDIFL mandates long-term monitoring during the facial growth period of the child. Follow-up care by the paediatric dentist and maxillofacial surgeon has been required to manage all aspects of this congenital malformation. This rare disorder has many implications affecting child's facial aesthetics, psychological well being, developing occlusion and risk of dental caries. A multi-disciplinary approach is needed for management of this condition.

Epi-detected quadruple-modal nonlinear optical microscopy for label-free imaging of the tooth

Energy Technology Data Exchange (ETDEWEB)

Wang, Zi; Zheng, Wei; Huang, Zhiwei, E-mail: biehzw@nus.edu.sg [Optical Bioimaging Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576 (Singapore); Stephen Hsu, Chin-Ying [Department of Dentistry, Faculty of Dentistry, National University of Singapore and National University Health System, Singapore 119083 (Singapore)

2015-01-19

We present an epi-detected quadruple-modal nonlinear optical microscopic imaging technique (i.e., coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), third-harmonic generation (THG), and two-photon excited fluorescence (TPEF)) based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of the tooth. We demonstrate that high contrast ps-CARS images covering both the fingerprint (500–1800 cm{sup −1}) and high-wavenumber (2500–3800 cm{sup −1}) regions can be acquired to uncover the distributions of mineral and organic biomaterials in the tooth, while high quality TPEF, SHG, and THG images of the tooth can also be acquired under ps laser excitation without damaging the samples. The quadruple-modal nonlinear microscopic images (CARS/SHG/THG/TPEF) acquired provide better understanding of morphological structures and biochemical/biomolecular distributions in the dentin, enamel, and the dentin-enamel junction of the tooth without labeling, facilitating optical diagnosis and characterization of the tooth in dentistry.

Osteoblast and osteoclast behaviors in the turnover of attachment bones during medaka tooth replacement.

Science.gov (United States)

Mantoku, Akiko; Chatani, Masahiro; Aono, Kazushi; Inohaya, Keiji; Kudo, Akira

2016-01-15

Tooth replacement in polyphyodont is a well-organized system for maintenance of homeostasis of teeth, containing the dynamic structural change in skeletal tissues such as the attachment bone, which is the supporting element of teeth. Histological analyses have revealed the character of tooth replacement, however, the cellular mechanism of how skeletal tissues are modified during tooth replacement is largely unknown. Here, we showed the important role of osteoblasts for controlling osteoclasts to modify the attachment bone during tooth replacement in medaka pharyngeal teeth, coupled with an osterix-DsRed/TRAP-GFP transgenic line to visualize osteoblasts and osteoclasts. In the turnover of the row of attachment bones, these bones were resorbed at the posterior side where most developed functional teeth were located, and generated at the anterior side where teeth were newly erupted, which caused continuous tooth replacement. In the cellular analysis, osteoclasts and osteoblasts were located at attachment bones separately, since mature osteoclasts were localized at the resorbing side and osteoblasts gathered at the generating side. To demonstrate the role of osteoclasts in tooth replacement, we established medaka made deficient in c-fms-a by TALEN. c-fms-a deficient medaka showed hyperplasia of attachment bones along with reduced bone resorption accompanied by a low number of TRAP-positive osteoclasts, indicating an important role of osteoclasts in the turnover of attachment bones. Furthermore, nitroreductase-mediated osteoblast-specific ablation induced disappearance of osteoclasts, indicating that osteoblasts were essential for maintenance of osteoclasts for the proper turnover. Taken together, our results suggested that the medaka attachment bone provides the model to understand the cellular mechanism for tooth replacement, and that osteoblasts act in the coordination of bone morphology by supporting osteoclasts. Copyright © 2015 Elsevier Inc. All rights reserved.

Autogenous tooth transplantation for replacing a lost tooth: case reports

Directory of Open Access Journals (Sweden)

Ji-Youn Kang

2013-02-01

Full Text Available The autogenous tooth transplantation is an alternative treatment replacing a missing tooth when a suitable donor tooth is available. It is also a successful treatment option to save significant amount of time and cost comparing implants or conventional prosthetics. These cases, which required single tooth extraction due to deep caries and severe periodontal disease, could have good results by transplanting non-functional but sound donor tooth to the extraction site.

Petrography and petrology of the Nornahraun eruption of the Bárðarbunga volcanic system, Iceland

Science.gov (United States)

Guðfinnsson, Guðmundur H.; Halldórsson, Sæmundur Ari; Bali, Enikő; Jakobsson, Sigurður; Sverrisdóttir, Guðrún; Höskuldssson, Ármann; Riishuus, Morten S.; Þórðarson, Þorvaldur; The 2014 Nornahraun Eruption Team

2015-04-01

The on-going fissure eruption north of Dyngjujökull is becoming the largest of its kind in Iceland since the 1783-84 Laki eruption. The erupted lava is olivine tholeiite, containing up to 5% normative olivine. It is relatively macrocryst-poor, initially containing less than 1% phenocrysts by volume, increasing to over 1% as the eruption has progressed. Plagioclase is the dominant macrocryst phase but olivine and augite are also present. In most of the samples, crystallization of the groundmass is substantial, with plagioclase and augite as the key groundmass minerals and minor olivine. It features subophitic texture, typical for olivine tholeiites, where the interstitial glass contains dendritic Fe-Ti oxide. During the first two months of the eruption, magma composition has been constant, displaying uniform major and trace element composition and nearly uniform isotopic compositions (Halldórsson et al. (a), this session). The major and trace element contents, in addition to the isotope ratios of lead, are indistinguishable from basalts in the Bárðarbunga volcanic system (Halldórsson et al. (b), this session). The compositional trends are consistent with crystallization along the ol-plag-cpx cotectic. Crystallization depth estimates, based on the pressure dependence of the cotectic (Yang et al., 1996), indicate that the magma equilibrated at a minimum depth between 6-9 km, consistent with depth estimates derived from CO2-bearing fluid inclusions trapped in plagioclase phenocrysts (Bali et al., this session). The bulk of the earthquakes associated with this volcano-tectonic episode are also in this range (e.g., Sigmundsson et al., 2015). Calculations with several different magma geothermometers suggest that the temperature of the magma as it rises to the surface is about 1170-1180°C, in good agreement with on-site measurements by thermal imaging cameras. The eruption has been characterized by steady, high emission of SO2. The sulfur-rich nature of the lava is

A comparison of tooth structure in Neanderthals and early Homo sapiens sapiens: a radiographic study.

OpenAIRE

Zilberman, U; Smith, P

1992-01-01

Tooth components of 1st and 2nd erupted permanent molars were measured from standardised radiographs of Homo sapiens sapiens and Homo sapiens neanderthalensis. Enamel height was greater in Homo sapiens sapiens but pulp height and width and the height of the enamel to floor of the pulp chamber were greater in Homo sapiens neanderthalensis. Dentine height, crown width and enamel width showed similar results in the two groups. Unerupted first molars were measured to analyse the influence of func...

Periodontal probing of an impacted tooth recovered through a surgical-orthodontic approach: a case report.

Science.gov (United States)

Dinoi, Maria Teresa; Lacarbonara, Mariano; Dimartino, Salvatore; Monaco, Annalisa; Marzo, Giuseppe

2014-01-27

The aim of this work was to assess the periodontal support of a central upper incisor recovered through a surgical-orthodontic approach compared to the spontaneously erupted contralateral incisor. This case study describes an 8-year-old Caucasian female with an impacted upper right central incisor. Surgical-orthodontic treatment was performed to reset the impacted dental element in the arch. Periodontal probing was performed of all sites (mesio-buccal, central-buccal, disto-buccal, mesio-palatal, central-palatal and disto-palatal) of the recovered impacted tooth and the contralateral tooth. The results were compared to determine whether the treated element showed signs of periodontal injury. Most of the probing results on both her right and left incisors gave values of approximately 3mm, which were not considered pathological. Both dental elements had adequate and physiological osseous attachments.

Magma fluxes and recurreance rate of eruptions at Nevado de Toluca volcano (Mexico)

Science.gov (United States)

Weber, Gregor; Probst, Line; Arce, José L.; Caricchi, Luca

2017-04-01

Forecasting the frequency and size of volcanic eruptions is a long-term goal for hazard mitigation. The frequency at which a given crustal magmatic system is driven towards a critical state and the magnitude of the resulting volcanic events are linked to the supply rate of fresh magma, crustal properties, and tectonic setting. Our ability to forecast the recurrence rate of eruptions is hampered by the lack of data on key variables such as the average magma flux locally and globally. The aim of this project is to identify the average magma supply rate and injection frequency for eruptions of different magnitude and eruptive style. We centred our study at Nevado de Toluca in Mexico, a subduction-related volcano with an eruptive history spanning about 1.5 million years of comparatively well documented effusive and explosive eruptions dominantly of dacitic composition. We carry out in-situ high precision zircon geochronology for a sequence of eruptions of different magnitude to obtain a distribution of crystal ages from which average crustal magma fluxes can be calculated. Eruptive fluxes will be constrained by extracting lava flow volumes from a digital elevation model. A combination of whole rock and mineral chemistry will provide quantitative insights on petrogenetic processes and on the frequency at which intensive parameters changed within the magma reservoir before the eruptions. Our results will be integrated in a global database including other volcanic systems and literature data to attempt to identify similarities and differences between magmatic reservoirs feeding volcanic eruptions of different magnitude. The final target of this project is to identify the physical factors controlling the recurrence rate of volcanic eruptions at regional and global scale.

Pre-eruptive volatile and erupted gas phase characterization of the 2014 basalt of Bárðarbunga volcanic system, Iceland.

Science.gov (United States)

Haddadi, Baptiste; Moune, Séverine; Sigmarsson, Olgeir; Gauthier, Pierre-Jean; Gouhier, Mathieu

2015-04-01

The 2014 Holuhraun eruption on the Bárðarbunga Volcanic System is the largest fissure eruption in Iceland since the 1783 Laki eruption. The eruption started end of August 2014 and has been characterized by large emission of SO2 into the atmosphere. It provides a rare opportunity to study in details magmatic and degassing processes during a large-volume fissure eruption. In order to characterize the pre-eruptive magmatic composition and to assess the plume chemistry at the eruption site, lava and tephra were sampled together with the eruption plume. The basalt composition is olivine tholeiite with MgO close to 7 wt%. It is phenocryst-poor with plagioclase as the dominant mineral phase but olivine and clinopyroxene are also present together with sulphide globules composed principally of pyrite and chalcopyrite. The volatile (S, Cl and F) and major element concentrations were measured by the electron microprobe in melt inclusions (MIs) trapped in plagioclase and clinopyroxene and groundmass glass. The MIs composition ranges from fairly primitive basaltic compositions (MgO: 9.03 wt%) down to evolved qz-tholeiites (MgO: 5.57 wt%), with estimated pre-eruptive S concentrations of 1500 ppm. Tephra groundmass glass contains 400 ppm S, whereas Cl and F concentrations are respectively slightly lower and indistinguishable from those in the MIs. This implies limited exsolution of halogens but 75% of the initial sulphur content. Relatively to their total iron content, MIs are sulphur saturated, and their oxygen fugacity close to the FMQ buffer. The difference between the estimated initial volatile concentrations measured in the MIs and in the tephra groundmass (i.e. the so-called petrological method) yields 7.2 Mt SO2, limited HCl and no HF atmospheric mass loading from the Holuhraun 2014 eruption. The SO2/HCl molar ratio of the gas phase, calculated from the MIs, is 13 and 14, respectively, using average and estimated pre-eruptive S and Cl concentrations in the MIs. Filter

Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon.

Science.gov (United States)

Geiger, Harri; Barker, Abigail K; Troll, Valentin R

2016-10-07

Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano's underlying magma supply system is sparse. To characterize Mt. Cameroon's magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano's two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs.

The role of microbial iron reduction in the formation of Proterozoic molar tooth structures

Science.gov (United States)

Hodgskiss, Malcolm S. W.; Kunzmann, Marcus; Poirier, André; Halverson, Galen P.

2018-01-01

Molar tooth structures are poorly understood early diagenetic, microspar-filled voids in clay-rich carbonate sediments. They are a common structure in sedimentary successions dating from 2600-720 Ma, but do not occur in rocks older or younger, with the exception of two isolated Ediacaran occurrences. Despite being locally volumetrically significant in carbonate rocks of this age, their formation and disappearance in the geological record remain enigmatic. Here we present iron isotope data, supported by carbon and oxygen isotopes, major and minor element concentrations, and total organic carbon and sulphur contents for 87 samples from units in ten different basins spanning ca. 1900-635 Ma. The iron isotope composition of molar tooth structures is almost always lighter (modal depletion of 2‰) than the carbonate or residue components in the host sediment. We interpret the isotopically light iron in molar tooth structures to have been produced by dissimilatory iron reduction utilising Fe-rich smectites and Fe-oxyhydroxides in the upper sediment column. The microbial conversion of smectite to illite results in a volume reduction of clay minerals (∼30%) while simultaneously increasing pore water alkalinity. When coupled with wave loading, this biogeochemical process is a viable mechanism to produce voids and subsequently precipitate carbonate minerals. The disappearance of molar tooth structures in the mid-Neoproterozoic is likely linked to a combination of a decrease in smectite abundance, a decline in the marine DIC reservoir, and an increase in the concentration of O2 in shallow seawater.

Periostin is an extracellular matrix protein required for eruption of incisors in mice

International Nuclear Information System (INIS)

Kii, Isao; Amizuka, Norio; Minqi, Li; Kitajima, Satoshi; Saga, Yumiko; Kudo, Akira

2006-01-01

A characteristic tooth of rodents, the incisor continuously grows throughout life by the constant formation of dentin and enamel. Continuous eruption of the incisor is accompanied with formation of shear zone, in which the periodontal ligament is remodeled. Although the shear zone plays a role in the remodeling, its molecular biological aspect is barely understood. Here, we show that periostin is essential for formation of the shear zone. Periostin -/- mice showed an eruption disturbance of incisors. Histological observation revealed that deletion of periostin led to disappearance of the shear zone. Electron microscopy revealed that the disappearance of the shear zone resulted from a failure in digestion of collagen fibers in the periostin -/- mice. Furthermore, immunohistochemical analysis using anti-periostin antibodies demonstrated the restricted localization of periostin protein in the shear zone. Periostin is an extracellular matrix protein, and immunoelectron microscopy showed a close association of periostin with collagen fibrils in vivo. These results suggest that periostin functions in the remodeling of collagen matrix in the shear zone

Age determination in roe deer - a new approach to tooth wear evaluated on known age individuals

DEFF Research Database (Denmark)

Høye, Toke Thomas

2006-01-01

A novel, simple, and objective method is presented for ageing roe deer Capreolus capreolus (Linnaeus, 1758) evaluated on 471 lower jaws from roe deer of known age (351 with permanent premolars). It is based on tooth eruption patterns and presence/absence of wear characters in jaws from roe deer...... integrated in a scoring system. Permanent cheek teeth emerge in May-July in the year after birth, which enables precise age determination of individuals with deciduous premolars. For individuals with permanent cheek teeth, the method provides the correct age for all individuals younger than 13 months...... originate from two separated Danish roe deer populations exposed to contrasting habitats, but no difference in wear rate is found between populations. Thus, previous concern about the validity of age determination methods based on tooth wear may have been overstated. The findings demonstrate that objective...

Intake of dairy calcium and tooth loss among Danish men and women

DEFF Research Database (Denmark)

Adegboye, Amanda R A; Twetman, Svante; Christensen, Lisa B

2011-01-01

and 1988 through 1993 and 1994. Total calcium intake, estimated by a 7-d food record or a a diet history interview, was divided into dairy and non-dairy forms of calcium. RESULTS: In men, a 10-fold increase in dairy calcium intake was significantly associated with a decreased risk of tooth loss (incidence......-rate ratio 0.32, 95% confidence interval 0.15-0.68) even after an adjustment for tooth count in 1987 and 1988, age, education, and civil status (model 1), smoking, alcohol consumption, sucrose intake, and use of vitamin and/or mineral supplements (model 2), time since last dental visit and the presence...

Opal-A in Glassy Pumice, Acid Alteration, and the 1817 Phreatomagmatic Eruption at Kawah Ijen (Java), Indonesia

Science.gov (United States)

Lowenstern, Jacob B.; van Hinsberg, Vincent; Berlo, Kim; Liesegang, Moritz; Iacovino, Kayla; Bindeman, Ilya N.; Wright, Heather M.

2018-02-01

that post-eruption alteration of pumice is more likely than pre-eruption envelopment of euhedral opal-replaced phenocrysts in dacitic melt. At Ijen and elsewhere, the ascent of magma into hydrous acid-altered mineral assemblages (e.g., opal, kaolinite, alunite) could induce rapid dehydration of hydrous minerals and amorphous materials, generating considerable steam and contributing to magmatic-hydrothermal and phreatomagmatic explosions.

Opal-A in glassy pumice, acid alteration, and the 1817 phreatomagmatic eruption at Kawah Ijen (Java), Indonesia

Science.gov (United States)

Lowenstern, Jacob B.; van Hinsberg, Vincent; Berlo, Kim; Liesegang, Moritz; Iacovino, Kayla D.; Bindeman, Ilya N.; Wright, Heather M.

2018-01-01

that post-eruption alteration of pumice is more likely than pre-eruption envelopment of euhedral opal-replaced phenocrysts in dacitic melt. At Ijen and elsewhere, the ascent of magma into hydrous acid-altered mineral assemblages (e.g., opal, kaolinite, alunite) could induce rapid dehydration of hydrous minerals and amorphous materials, generating considerable steam and contributing to magmatic-hydrothermal and phreatomagmatic explosions.

Helium ion microscopy of enamel crystallites and extracellular tooth enamel matrix.

Science.gov (United States)

Bidlack, Felicitas B; Huynh, Chuong; Marshman, Jeffrey; Goetze, Bernhard

2014-01-01

An unresolved problem in tooth enamel studies has been to analyze simultaneously and with sufficient spatial resolution both mineral and organic phases in their three dimensional (3D) organization in a given specimen. This study aims to address this need using high-resolution imaging to analyze the 3D structural organization of the enamel matrix, especially amelogenin, in relation to forming enamel crystals. Chemically fixed hemi-mandibles from wild type mice were embedded in LR White acrylic resin, polished and briefly etched to expose the organic matrix in developing tooth enamel. Full-length amelogenin was labeled with specific antibodies and 10 nm immuno-gold. This allowed us to use and compare two different high-resolution imaging techniques for the analysis of uncoated samples. Helium ion microscopy (HIM) was applied to study the spatial organization of organic and mineral structures, while field emission scanning electron microscopy (FE-SEM) in various modes, including backscattered electron detection, allowed us to discern the gold-labeled proteins. Wild type enamel in late secretory to early maturation stage reveals adjacent to ameloblasts a lengthwise parallel alignment of the enamel matrix proteins, including full-length amelogenin proteins, which then transitions into a more heterogeneous appearance with increasing distance from the mineralization front. The matrix adjacent to crystal bundles forms a smooth and lacey sheath, whereas between enamel prisms it is organized into spherical components that are interspersed with rod-shaped protein. These findings highlight first, that the heterogeneous organization of the enamel matrix can be visualized in mineralized en bloc samples. Second, our results illustrate that the combination of these techniques is a powerful approach to elucidate the 3D structural organization of organic matrix molecules in mineralizing tissue in nanometer resolution.

Helium ion microscopy of enamel crystallites and extracellular tooth enamel matrix

Directory of Open Access Journals (Sweden)

Felicitas B Bidlack

2014-10-01

Full Text Available An unresolved problem in tooth enamel studies has been to analyze simultaneously and with sufficient spatial resolution both mineral and organic phases in their three dimensional (3D organization in a given specimen. This study aims to address this need using high-resolution imaging to analyze the 3D structural organization of the enamel matrix, especially amelogenin, in relation to forming enamel crystals. Chemically fixed hemi-mandibles from wild type mice were embedded in LR White acrylic resin, polished and briefly etched to expose the organic matrix in developing tooth enamel. Full-length amelogenin was labeled with specific antibodies and 10 nm immuno-gold. This allowed us to use and compare two different high-resolution imaging techniques for the analysis of uncoated samples. Helium ion microscopy (HIM was applied to study the spatial organization of organic and mineral structures, while field emission scanning electron microscopy (FE-SEM in various modes, including backscattered electron detection, allowed us to discern the gold-labeled proteins. Wild type enamel in late secretory to early maturation stage reveals adjacent to ameloblasts a lengthwise parallel alignment of the enamel matrix proteins, including full-length amelogenin proteins, which then transitions into a more heterogeneous appearance with increasing distance from the mineralization front. The matrix adjacent to crystal bundles forms a smooth and lacey sheath, whereas between enamel prisms it is organized into spherical components that are interspersed with rod-shaped protein. These findings highlight first, that the heterogeneous organization of the enamel matrix can be visualized in mineralized en bloc samples. Second, our results illustrate that the combination of these techniques is a powerful approach to elucidate the 3D structural organization of organic matrix molecules in mineralizing tissue in nanometer resolution.

Fine structure of the mineralized teeth of the chiton Acanthopleura echinata (Mollusca: Polyplacophora).

Science.gov (United States)

Wealthall, Rosamund J; Brooker, Lesley R; Macey, David J; Griffin, Brendan J

2005-08-01

The major lateral teeth of the chiton Acanthopleura echinata are composite structures composed of three distinct mineral zones: a posterior layer of magnetite; a thin band of lepidocrocite just anterior to this; and apatite throughout the core and anterior regions of the cusp. Biomineralization in these teeth is a matrix-mediated process, in which the minerals are deposited around fibers, with the different biominerals described as occupying architecturally discrete compartments. In this study, a range of scanning electron microscopes was utilized to undertake a detailed in situ investigation of the fine structure of the major lateral teeth. The arrangement of the organic and biomineral components of the tooth is similar throughout the three zones, having no discrete borders between them, and with crystallites of each mineral phase extending into the adjacent mineral zone. Along the posterior surface of the tooth, the organic fibers are arranged in a series of fine parallel lines, but just within the periphery their appearance takes on a "fish scale"-like pattern, reflective of the cross section of a series of units that are overlaid, and offset from each other, in adjacent rows. The units are approximately 2 microm wide and 0.6 microm thick and comprise biomineral plates separated by organic fibers. Two types of subunits make up each "fish scale": one is elongate and curved and forms a trough, in which the other, rod-like unit, is nestled. Adjacent rod and trough units are aligned into large sheets that define the fracture plane of the tooth. The alignment of the plates of rod-trough units is complex and exhibits extreme spatial variation within the tooth cusp. Close to the posterior surface the plates are essentially horizontal and lie in a lateromedial plane, while anteriorly they are almost vertical and lie in the posteroanterior plane. An understanding of the fine structure of the mineralized teeth of chitons, and of the relationship between the organic and

Effect of a chlorhexidine/thymol and a fluoride varnish on caries development in erupting permanent molars: a comparative study.

Science.gov (United States)

Flamee, S; Gizani, S; Caroni, C; Papagiannoulis, L; Twetman, S

2015-12-01

To compare the caries preventive effect of a chlorhexidine/thymol-containing antibacterial varnish with a fluoride varnish when topically applied during the eruption of permanent molars. The study group consisted of 189 patients, 5-14 years of age, with one 1st or 2nd permanent molar in the process of eruption. After stratification for type of molar and stage of eruption, the patients were randomised to either quarterly topical applications with an antibacterial varnish (Cervitec(®) Plus; CV group) or biannual applications with a fluoride varnish plus biannual treatments with placebo varnish (Fluor Protector; FV group). The duration of the study was 2 years. The primary endpoint was caries incidence (initial and cavitated) in the erupting molars and the secondary outcome was salivary mutans streptococci (MS) counts. The groups were balanced with respect to socio-economy, oral hygiene, dietary habits and caries experience at baseline. The dropout rate was 11.6 %. The caries incidence was low (< 10 %) in both groups and there was no significant difference between the CV and FV groups with respect to occlusal caries development in the erupting molars (relative risk 1.08, 95 % CI 0.94-1.25). Significantly lower levels of salivary MS were disclosed in the CV group at the end of the study (p < 0.05). No difference in occlusal caries development in young permanent molars was displayed after topical applications of either a chlorhexidine/thymol varnish or a fluoride varnish during tooth eruption.

CD44 is involved in mineralization of dental pulp cells.

Science.gov (United States)

Chen, Kuan-Liang; Huang, Yu-Yuan; Lung, Jrhau; Yeh, Ying-Yi; Yuan, Kuo

2013-03-01

CD44 is a transmembrane glycoprotein with various biological functions. Histologic studies have shown that CD44 is strongly expressed in odontoblasts at the appositional stage of tooth development. We investigated whether CD44 is involved in the mineralization of dental pulp cells. Ten human third molars with incomplete root formation were collected and processed for immunohistochemistry of CD44. Dental pulp cells isolated from another 5 human third molars were assayed for their viability, alkaline phosphatase activity, and alizarin red staining in vitro after silencing stably their expression of CD44 by using the short hairpin RNA technique. The CD44 knockdown cells were cultured on a collagen sponge and transplanted subcutaneously into the dorsal surfaces of immunocompromised mice. After 6 weeks, the subcutaneous tissues were processed for alizarin red staining and immunohistochemistry of human specific antigen. The dental pulp cells transduced with control short hairpin RNA were used as the control in all assays. CD44 is expressed in odontogenic cells with active mineral deposition during tooth development. Odontoblasts in the root ends of immature teeth express a stronger CD44 signal compared with those in the crown portion. When CD44 expression was stably suppressed in dental pulp cells, their mineralization activities were substantially decreased in both in vitro and in vivo assays. CD44 may play a crucial role in the initial mineralization of tooth-associated structures. However, further studies are required to clarify the underlying mechanisms. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Disease: H00680 [KEGG MEDICUS

Lifescience Database Archive (English)

Full Text Available H00680 Primary failure of tooth eruption Primary failure of tooth eruption (PFE) i...al features and aetiological basis of primary eruption failure. ... JOURNAL ... Eur J Orthod 28:535-40 (2006) DO...of-function mutations in familial, nonsyndromic primary failure of tooth eruption. ... JOURNAL ... Am J Hum Genet 83:781-6 (2008) DOI:10.1016/j.ajhg.2008.11.006

Graded changes in enamel component volumes resulted from a short tooth bleaching procedure.

Science.gov (United States)

Ferreira, Artemisa Fernanda Moura; Perez, Flávia Maria de Moraes Ramos; Limeira Júnior, Francisco de Assis; de Moura, Mirella de Fátima Liberato; de Sousa, Frederico Barbosa

2016-05-01

To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure. Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching. Tooth shade changes were significant (pbleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p99%). Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward. Copyright © 2016 Elsevier Ltd. All rights reserved.

2H Stable Isotope Analysis of Tooth Enamel: A Pilot Study

Science.gov (United States)

Holobinko, Anastasia; Kemp, Helen; Meier-Augenstein, Wolfram; Prowse, Tracy; Ford, Susan

2010-05-01

Stable isotope analysis of biogenic tissues such as tooth enamel and bone mineral has become a well recognized and increasingly important method for determining provenance of human remains, and has been used successfully in bioarchaeological studies as well as forensic investigations (Lee-Thorp, 2008; Meier-Augenstein and Fraser, 2008). Particularly, 18O and 2H stable isotopes are well established proxies as environmental indicators of climate (temperature) and source water and are therefore considered as indicators of geographic life trajectories of animals and humans (Hobson et al., 2004; Schwarcz and Walker, 2006). While methodology for 2H analysis of human hair, fingernails, and bone collagen is currently used to determine geographic origin and identify possible migration patterns, studies involving the analysis of 2H in tooth enamel appear to be nonexistent in the scientific literature. The apparent lack of research in this area is believed to have two main reasons. (1) Compared to the mineral calcium hydroxylapatite Ca10(PO4)6(OH)2, in tooth enamel forming bio-apatite carbonate ions replace some of the hydroxyl ions at a rate of one CO32 replacing two OH, yet published figures for the degree of substitution vary (Wopenka and Pasteris, 2005). (2) Most probably due to the aforementioned no published protocols exist for sample preparation and analytical method to obtain δ2H-values from the hydroxyl fraction of tooth enamel. This dilemma has been addressed through a pilot study to establish feasibility of 2H stable isotope analysis of ground tooth enamel by continuous-flow isotope ratio mass spectrometry (IRMS) coupled on-line to a high-temperature conversion elemental analyzer (TC/EA). An array of archaeological and modern teeth has been analyzed under different experimental conditions, and results from this pilot study are being presented. References: Lee-Thorp, J.A. (2008) Archaeometry, 50, 925-950 Meier-Augenstein, W. and Fraser, I. (2008) Science & Justice

Assessing Eruption Column Height in Ancient Flood Basalt Eruptions

Science.gov (United States)

Glaze, Lori S.; Self, Stephen; Schmidt, Anja; Hunter, Stephen J.

2015-01-01

A buoyant plume model is used to explore the ability of flood basalt eruptions to inject climate-relevant gases into the stratosphere. An example from the 1986 Izu-Oshima basaltic fissure eruption validates the model's ability to reproduce the observed maximum plume heights of 12-16 km above sea level, sustained above fire-fountains. The model predicts maximum plume heights of 13-17 km for source widths of between 4-16 m when 32% (by mass) of the erupted magma is fragmented and involved in the buoyant plume (effective volatile content of 6 wt%). Assuming that the Miocene-age Roza eruption (part of the Columbia River Basalt Group) sustained fire-fountains of similar height to Izu-Oshima (1.6 km above the vent), we show that the Roza eruption could have sustained buoyant ash and gas plumes that extended into the stratosphere at approximately 45 deg N. Assuming 5 km long active fissure segments and 9000 Mt of SO2 released during explosive phases over a 10-15 year duration, the approximately 180 km of known Roza fissure length could have supported approximately 36 explosive events/phases, each with a duration of 3-4 days. Each 5 km fissure segment could have emitted 62 Mt of SO2 per day into the stratosphere while actively fountaining, the equivalent of about three 1991 Mount Pinatubo eruptions per day. Each fissure segment could have had one to several vents, which subsequently produced lava without significant fountaining for a longer period within the decades-long eruption. Sensitivity of plume rise height to ancient atmospheric conditions is explored. Although eruptions in the Deccan Traps (approximately 66 Ma) may have generated buoyant plumes that rose to altitudes in excess of 18 km, they may not have reached the stratosphere because the tropopause was substantially higher in the late Cretaceous. Our results indicate that some flood basalt eruptions, such as Roza, were capable of repeatedly injecting large masses of SO2 into the stratosphere. Thus sustained

Radicular Cyst With Actinomycotic Infection in an Upper Anterior Tooth

Directory of Open Access Journals (Sweden)

Shuei-Kuen Tseng

2009-10-01

Full Text Available Actinomycosis is an infection caused by filamentous, branching, Gram-positive anaerobic bacteria. It rarely infects the jawbone. This case report describes a patient with a left maxillary central incisor with an apical lesion and actinomycotic infection. A 23-year-old male patient underwent conventional root canal treatment of tooth 21, in a local dental clinic for about 1 year. However, percussion pain and a sinus tract that originated from tooth 21 were still present after treatment. Nonsurgical root canal treatment of tooth 21 was performed again but failed to relieve the symptoms. Therefore, apicoectomy and retrograde filling of the apical root canal with mineral trioxide aggregate were carried out. Periradicular bony defect was grafted by biocompatible material, and postoperative antibiotics (250 mg amoxicillin were given three times daily for 5 days. Pathological examination of the removed periapical tissue showed a radicular cyst with actinomycosis. At the 9-month postoperative recall, the sinus tract had disappeared and radiographic examination showed healing of the apical lesion. Periradicular actinomycosis is one important reason for failure of nonsurgical endodontic treatment. Clinically, if the tooth shows a recurrent sinus tract and poor response to conventional root canal treatment combined with antibiotic control, apical actinomycotic infection should be highly suspected, and an alternative endodontic surgical approach is needed for successful treatment.

Bromine release during Plinian eruptions along the Central American Volcanic Arc

Science.gov (United States)

Hansteen, T. H.; Kutterolf, S.; Appel, K.; Freundt, A.; Perez-Fernandez, W.; Wehrmann, H.

2010-12-01

Volcanoes of the Central American Volcanic Arc (CAVA) have produced at least 72 highly explosive eruptions within the last 200 ka. The eruption columns of all these “Plinian” eruptions reached well into the stratosphere such that their released volatiles may have influenced atmospheric chemistry and climate. While previous research has focussed on the sulfur and chlorine emissions during such large eruptions, we here present measurements of the heavy halogen bromine by means of synchrotron radiation induced micro-XRF microanalysis (SR-XRF) with typical detection limits at 0.3 ppm (in Fe rich standard basalt ML3B glass). Spot analyses of pre-eruptive glass inclusions trapped in minerals formed in magma reservoirs were compared with those in matrix glasses of the tephras, which represent the post-eruptive, degassed concentrations. The concentration difference between inclusions and matrix glasses, multiplied by erupted magma mass determined by extensive field mapping, yields estimates of the degassed mass of bromine. Br is probably hundreds of times more effective in destroying ozone than Cl, and can accumulate in the stratosphere over significant time scales. Melt inclusions representing deposits of 22 large eruptions along the CAVA have Br contents between 0.5 and 13 ppm. Br concentrations in matrix glasses are nearly constant at 0.4 to 1.5 ppm. However, Br concentrations and Cl/Br ratios vary along the CAVA. The highest values of Br contents (>8 ppm) and lowest Cl/Br ratios (170 to 600) in melt inclusions occur across central Nicaragua and southern El Salvador, and correlate with bulk-rock compositions of high Ba/La > 85 as well as low La/Yb discharged 700 kilotons of Br. On average, each of the remaining 21 CAVA eruptions studied have discharged c.100 kilotons of bromine. During the past 200 ka, CAVA volcanoes have emitted a cumulative mass of 3.2 Mt of Br through highly explosive eruptions. There are six periods in the past (c. 2ka, 6ka, 25ka, 40ka, 60ka, 75

The evolution of hydrous magmas in the Tongariro Volcanic Centre : the 10 ka Pahoka-Mangamate eruptions

International Nuclear Information System (INIS)

Auer, A.; Palin, J.M.; White, J.D.L.; Nakagawa, M.; Stirling, C.

2015-01-01

The majority of arc-type andesites in the Tongariro Volcanic Centre are highly porphyritic, hornblende-free, two-pyroxene andesites. An exception is tephras from the c. 10,000 ka Pahoka-Mangamate event. Magmas of these Plinian eruptions bypassed the extensive crustal mush columns under the central volcanoes and sequentially derived a series of almost aphyric rocks spanning a compositional range from dacite to basaltic andesite. Mineral composition, trace element and isotopic data suggest that this eruptive series tapped a mid-crustal magma reservoir, resulting in the initial eruption of an hydrous dacitic magma and several following eruptions characterised by less-evolved and less-hydrous compositions at progressively higher temperatures and substantially lower 87 Sr/ 86 Sr ratios. Systematic changes in magma chemistry are also reflected in a sequential change in phenocryst content starting with an early hornblende-plagioclase-dominated assemblage to a late olivine-plagioclase-dominated assemblage. (author).

Developmental enamel and anatomical tooth defects in dogs – Experience from veterinary dental referral practice and review of the literature

Directory of Open Access Journals (Sweden)

Sonja Catharina Boy

2016-02-01

Full Text Available Developmental tooth abnormalities in dogs are uncommon in general veterinary practice but understanding thereof is important for optimal management in order to maintain gnathic function through conservation of the dentition. The purpose of this review is to discuss abnormalities of enamel structure and macroscopic tooth anatomy in dogs encountered in veterinary dental referral practice in South Africa and the United Kingdom. The basis of the pathogenesis, resultant clinical appearance and the management principles of each anomaly will be considered. Future research should aim to provide a detailed individual tooth mineralization schedule for dogs.

Tooth anatomy

Science.gov (United States)

... whole tooth. This area is known as the "pulp" of the tooth. The jawbone is attached to ... JC, eds. Robbins and Cotran Pathologic Basis of Disease . 9th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap ...

Enamel alteration following tooth bleaching and remineralization.

Science.gov (United States)

Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

2016-06-01

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

A REVIEW OF QUANTITATIVE METHODS FOR STUDIES OF MINERAL-CONTENT OF INTRAORAL INCIPIENT CARIES LESIONS

NARCIS (Netherlands)

TENBOSCH, JJ; ANGMARMANSSON, B

Modern prospective caries studies require the measurement of small changes in tooth mineral content. Quantitative measurements of changes in mineral content in a single caries lesion is desirable. Quantitative methods can be either destructive or non-destructive. The latter type permits longitudinal

Can dead man tooth do tell tales? Tooth prints in forensic identification.

Science.gov (United States)

Christopher, Vineetha; Murthy, Sarvani; Ashwinirani, S R; Prasad, Kulkarni; Girish, Suragimath; Vinit, Shashikanth Patil

2017-01-01

We know that teeth trouble us a lot when we are alive, but they last longer for thousands of years even after we are dead. Teeth being the strongest and resistant structure are the most significant tool in forensic investigations. Patterns of enamel rod end on the tooth surface are known as tooth prints. This study is aimed to know whether these tooth prints can become a forensic tool in personal identification such as finger prints. A study has been targeted toward the same. In the present in-vivo study, acetate peel technique has been used to obtain the replica of enamel rod end patterns. Tooth prints of upper first premolars were recorded from 80 individuals after acid etching using cellulose acetate strips. Then, digital images of the tooth prints obtained at two different intervals were subjected to biometric conversion using Verifinger standard software development kit version 6.5 software followed by the use of Automated Fingerprint Identification System (AFIS) software for comparison of the tooth prints. Similarly, each individual's finger prints were also recorded and were subjected to the same software. Further, recordings of AFIS scores obtained from images were statistically analyzed using Cronbach's test. We observed that comparing two tooth prints taken from an individual at two intervals exhibited similarity in many cases, with wavy pattern tooth print being the predominant type. However, the same prints showed dissimilarity when compared with other individuals. We also found that most of the individuals with whorl pattern finger print showed wavy pattern tooth print and few loop type fingerprints showed linear pattern of tooth prints. Further more experiments on both tooth prints and finger prints are required in establishing an individual's identity.

Holocene eruption history in Iceland - Eruption frequency vs. Tephra layer frequency

Science.gov (United States)

Oladottir, B. A.; Larsen, G.

2012-12-01

Volcanic deposits of all kinds are used to reconstruct eruption history of volcanoes and volcanic zones. In Iceland tephra is the ideal volcanic deposit to study eruption history as two out of every three eruptions taking place there during the last 11 centuries have been explosive, leaving tephra as their only product. If eruptions producing both lava and tephra are included three out of every four eruptions have produced tephra. Tephra dispersal and deposition depends on factors such as eruption magnitude, eruption cloud height, duration of eruption and prevailing wind directions at the time of eruption. Several outcrops around a particular volcano must therefore be measured to obtain optimal information of its eruption history. Vegetation in the area of deposition is also of great importance for its preservation. Tephra deposited on un-vegetated land is rapidly eroded by wind and water, and deposits up to few tens of cm thickness may be lost from the record. Such tephra deposited on grassy or forested land is at least partly sheltered from the wind after deposition. Soon after tephra deposition (how soon depends on tephra thickness) the root system of the vegetation creates an even better shelter for the tephra and when this stage is reached the tephra is preserved in the soil for millennia, given that no soil erosion takes place. Vegetation is often boosted in the first years after tephra deposition which in turn helps tephra preservation. A setback of using soil sections for reconstructing Holocene eruption history is the lack of soil at the beginning of the era but for that time period tephra records in lake and marine sediments can be used. When tephra stratigraphy in soil sections is measured to study eruption history and eruption frequency of a volcano it must be kept in mind that what is seen is in fact the tephra layer frequency. One section only shows tephra layers deposited in that location and more importantly only the layers preserved there. The

Age-related tooth wear differs between forest and savanna primates.

Directory of Open Access Journals (Sweden)

Jordi Galbany

Full Text Available Tooth wear in primates is caused by aging and ecological factors. However, comparative data that would allow us to delineate the contribution of each of these factors are lacking. Here, we contrast age-dependent molar tooth wear by scoring percent of dentine exposure (PDE in two wild African primate populations from Gabonese forest and Kenyan savanna habitats. We found that forest-dwelling mandrills exhibited significantly higher PDE with age than savanna yellow baboons. Mandrills mainly feed on large tough food items, such as hard-shell fruits, and inhabit an ecosystem with a high presence of mineral quartz. By contrast, baboons consume large amounts of exogenous grit that adheres to underground storage organs but the proportion of quartz in the soils where baboons live is low. Our results support the hypothesis that not only age but also physical food properties and soil composition, particularly quartz richness, are factors that significantly impact tooth wear. We further propose that the accelerated dental wear in mandrills resulting in flatter molars with old age may represent an adaptation to process hard food items present in their environment.

Dietary boron does not affect tooth strength, micro-hardness, and density, but affects tooth mineral composition and alveolar bone mineral density in rabbits fed a high-energy diet.

Science.gov (United States)

Hakki, Sema S; SiddikMalkoc; Dundar, Niyazi; Kayis, Seyit Ali; Hakki, Erdogan E; Hamurcu, Mehmet; Baspinar, Nuri; Basoglu, Abdullah; Nielsen, Forrest H; Götz, Werner

2015-01-01

The objective of this study was to determine whether dietary boron (B) affects the strength, density and mineral composition of teeth and mineral density of alveolar bone in rabbits with apparent obesity induced by a high-energy diet. Sixty female, 8-month-old, New Zealand rabbits were randomly assigned for 7 months into five groups as follows: (1) control 1, fed alfalfa hay only (5.91 MJ/kg and 57.5 mg B/kg); (2) control 2, high energy diet (11.76 MJ and 3.88 mg B/kg); (3) B10, high energy diet + 10 mg B gavage/kg body weight/96 h; (4) B30, high energy diet + 30 mg B gavage/kg body weight/96 h; (5) B50, high energy diet + 50 mg B gavage/kg body weight/96 h. Maxillary incisor teeth of the rabbits were evaluated for compression strength, mineral composition, and micro-hardness. Enamel, dentin, cementum and pulp tissue were examined histologically. Mineral densities of the incisor teeth and surrounding alveolar bone were determined by using micro-CT. When compared to controls, the different boron treatments did not significantly affect compression strength, and micro-hardness of the teeth, although the B content of teeth increased in a dose-dependent manner. Compared to control 1, B50 teeth had decreased phosphorus (P) concentrations. Histological examination revealed that teeth structure (shape and thickness of the enamel, dentin, cementum and pulp) was similar in the B-treated and control rabbits. Micro CT evaluation revealed greater alveolar bone mineral density in B10 and B30 groups than in controls. Alveolar bone density of the B50 group was not different than the controls. Although the B treatments did not affect teeth structure, strength, mineral density and micro-hardness, increasing B intake altered the mineral composition of teeth, and, in moderate amounts, had beneficial effects on surrounding alveolar bone.

The use of platelet rich plasma in the treatment of immature tooth with periapical lesion: a case report

Directory of Open Access Journals (Sweden)

Günseli Güven Polat

2014-08-01

Full Text Available This study describes the treatment of an immature permanent tooth with periapical lesion which was treated with regenerative approach using platelet rich plasma (PRP. The root canal of immature human permanent tooth with periapical lesion was gently debrided of necrotic tissue and disinfected with 2.5% NaOCl, and then medicated with triple antibiotic paste comprised of ciprofloxacin, metronidazole, and tetracycline. When the tooth was asymptomatic, PRP and mineral trioxide aggregate (MTA were placed into the root canal. Six months after PRP treatment, radiographical examination revealed resolution of the radiolucency and progressive thickening of the root wall and apical closure. Our findings suggest that PRP can be used for the treatment of immature permanent teeth with periapical lesion, as part of a regenerative endodontic treatment procedure. Keywords: Immature permanent tooth; Periapical lesions; Platelet rich plasma

The Tephra Layer From the Plinian Eruption in ™r‘faj”kull 1362, Southeast Iceland

Science.gov (United States)

Selbekk, R. S.

2002-12-01

Pyroclastic fallout from the 1362 eruption of ™r‘faj”kull forms one of the volcanic marker horizons of the North Atlantic. This contribution reports the mineralogical and geochemical characteristics of the ™r‘faj”kull 1362 fallout and its grain-size distribution. A non-rifting 120 km long volcanic lineament some 50 km east of the Eastern Rift-Zone of Iceland is defined by transitional and alkalic volcanic rocks resting unconformably on late Tertiary strata. ™r‘faj”kull which forms the southern termination of this off-rift liniment is an ice-covered stratovolcano (2200 masl) composed mostly of subglacially formed hyaloclastite ranging from basalts to rhyolites. The two historical (1100 yrs) eruptions of ™r‘faj”kull include a small explosive eruption in 1727 and a large devastating Plinian eruption associated with major lahars and a caldera collapse in 1362. Between 1 and 2 km3 dense rock equivalent or 5-10 km3 of rhyolitic pumice was erupted and the fallout was mainly towards ESE. Tentative modelling of the PT-conditions of the magma formation, based on glass/mineral equilibria, indicates that the source was a near-eutectic melt in equilibrium with fayalite, hedenbergite, oligoclase and hematite at some 0.2 GPa pressure. A profile through the fallout was sampled at elevation of about 1100 masl on the SE flank of the volcano. A deposit of 1.8 m thickness was collected in 14 units for examination of composition, mineralogy and grain-size distribution during the eruption. In the profile the fallout is fine grained vesicular glass (1-3% minerals, 3% lithic fragments) with bubble wall thickness in the low micron range. The high and even vesiculation of the glass indicates fast magma ascent and explains the extreme mechanical fragmentation within the eruptive column, yielding between 50 and 80 wt% of less than 0.25 mm grain size. A reconstruction of the Plinian phase, based on grain-size analysis and abundance of lithic fragments, reveals that the

Co-relation of variables as determined from panoramic radiograph and evaluating their significance in eruption of permanent mandibular third molar

Directory of Open Access Journals (Sweden)

Kushal Amin

2008-01-01

Full Text Available Purpose of the Study: Purpose of the study is to investigate whether the variables associated with the permanent mandibular third molar (PMM3 and arch dimensions could be co-related and significantly differentiated between a fully erupted and mesially impacted PMM3 among a set of Indian population. Study Design: A standardized panoramic radiograph was taken of subjects of age 21 years and above. Patients with missing tooth from mandibular arch, subjects undergoing or having history of orthodontic treatment, subjects having disto-angular, horizontal or vertical impacted PMM3 were excluded from the study. Subjects were divided into 2 groups: (1 mesially impacted PMM3 and (2 vertically erupted PMM3. Following measurements were taken from acetate paper tracing of standardized panoramic radiograph: (1 Angulation of long axis of PMM3 to permanent mandibular second molar (theta (2 Angulation of PMM 3 to base of mandible (theta 2 (3 Gonial angle (theta 3 (4 Mesio-distal width of PMM 3 (5 Retro molar space. From these measurements Ganss ratio (retro molar space /PMM3 crown width. was calculated. Results and Conclusion: Results revealed that angle theta 1, angle theta 2, retro molar space and Ganss ratio were positively co-related and highly significant variables associated with the mesially and vertically erupted teeth as measured on panoramic radiograph. Using these variables a long-term study can be carried out to predict the ultimate position of lower third molar in the arch so that if there is a probability of the tooth being impacted at a later age, a prophylactic germectomy can be performed at an early age.

Sea urchin tooth mineralization: Calcite present early in the aboral plumula

OpenAIRE

Stock, Stuart R.; Veis, Arthur; Xiao, Xianghui; Almer, Jonathan D.; Dorvee, Jason R.

2012-01-01

In both vertebrate bone, containing carbonated hydroxyapatite as the mineral phase, and in invertebrate hard tissue comprised of calcium carbonate, a popular view is that the mineral phase develops from a long-lived amorphous precursor which later transforms into crystal form. Important questions linked to this popular view are: When and where is the crystallized material formed, and is amorphous solid added subsequently to the crystalline substrate? Sea urchin teeth, in which the earliest mi...

Quantitative analysis of fluoride-induced hypermineralization of developing enamel in neonatal hamster tooth germs

Science.gov (United States)

Tros, G. H. J.; Lyaruu, D. M.; Vis, R. D.

1993-10-01

A procedure was developed for analysing the effect of fluoride on mineralization in the enamel of neonatal hamster molars during amelogenesis by means of the quantitative determination of the mineral content. In this procedure the distribution of calcium and mineral concentration was determined in sections containing developing tooth enamel mineral embedded in an organic epoxy resin matrix by means of the micro-PIXE technique. This allowed the determination of the calcium content along preselected tracks with a spatial resolution of 2 μm using a microprobe PIXE setup with a 3 MeV proton beam of 10 to 50 pA with a spot size of 2 μm in the track direction. In this procedure the X-ray yield is used as a measure for the calcium content. The thickness of each sample section is determined independently by measuring the energy loss of α-particles from a calibration source upon passing through the sample. The sample is considered as consisting of two bulk materials, allowing the correction for X-ray self-absorption and the calculation of the calcium concentration. The procedure was applied for measuring the distribution of mineral concentration in 2 μm thick sections taken from tooth germs of hamsters administered with NaF. The measurements indicated that a single intraperitoneal administration of 20 mg NaF/kg body weight to 4-to-5-day-old hamsters leads within 24 h to hypermineralization of certain focal enamel surface areas containing cystic lesions under transitional and early secretory ameloblasts. The mineral concentration there is substantially increased due to the fluoride treatment (35%, instead of 5 to 10% as in the controls), indicating that the normal mineralization process has been seriously disturbed. Furthermore it is found that using this technique the mineral concentration peaks at about 70% at the dentine-enamel junction, which is comparable to that reported for human dentine using other techniques.

Early removal of odontoma resulting in spontaneous eruption of the impacted teeth

Directory of Open Access Journals (Sweden)

Achmad Harijadi

2010-06-01

Full Text Available Background: Compound odontomas in the anterior maxilla during mixed dentition frequently cause obstruction to the eruption pathway of permanent upper anterior teeth. Removal of the odontomas may or may not lead to spontaneous eruption of the impacted teeth depending on the age when the surgery is performed, the size of the lesion, and the stage of tooth development of the involved teeth. Purpose: This paper attempts to emphasize the importance of early removal of compound odontoma to enable spontaneous eruption of the affected teeth. Case: A case of odontoma in the anterior maxilla causing failure of eruption and delayed root formation of upper right permanent lateral incisor and canine in a 10-year-old male patient is presented. Case management: The odontoma was surgically removed under general anesthesia and histology result confirmed the diagnosis of compound odontoma. A three-year post surgical follow up showed spontaneous eruption as well as continued root formation of the two affected teeth. Conclusion: Removal of odontoma may lead to spontaneous eruption of the affected teeth if their root development are not completed.Latar belakang: Compound odontoma pada daerah anterior maksila pada masa geligi pergantian sering menyebabkan hambatan erupsi pada gigi permanen penggantinya. Kemungkinan terjadinya erupsi spontan gigi permanen yang impaksi setelah pengambilan odontoma tergantung dari: umur penderita pada saat dilakukan operasi, ukuran lesi odontoma dan tahapan perkembangan gigi permanen yang terlibat. Tujuan: Laporan kasus ini ingin menekankan pentingnya pengambilan compound odontoma sedini mungkin untuk memberi kesempatan tumbuhnya gigi permanen yang terlibat dan erupsi secara spontan. Kasus: Ditampilkan sebuah kasus compound odontoma pada regio maksila anterior menyebabkan gagalnya erupsi dan terlambatnya pembentukan akar gigi insisif kedua dan kaninus permanent rahang atas kanan pada penderita anak laki-laki berumur 10 tahun

Erupted and nonerupted compound odontoma in prosthodontic patients: Report of two cases

Directory of Open Access Journals (Sweden)

Santosh R Patil

2016-01-01

Full Text Available The odontomas constitute most common benign odontogenic tumors of the jaws. Majority of odontomas are nonsymptomatic and are detected on routine radiographic examination. They represent up to 22% of all odontogenic tumors of the jaws. This lesion is composed of more than one type of odontogenic tissues and for this reason, it is also known a composite odontoma. In a 32-year-old male, well-defined small teeth like structure were noticed distal to maxillary second molars bilaterally which were confirmed radiologically and histopathologically as eruption odontome. In the second case, multiple miniature tooth-like structures of varying densities were observed pericoronally to the impacted canine on the X-ray, which was confirmed as compound histologically.

Tooth wear

Directory of Open Access Journals (Sweden)

Tušek Ivan

2014-01-01

Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

Large explosive basaltic eruptions at Katla volcano, Iceland: Fragmentation, grain size and eruption dynamics

Science.gov (United States)

Schmith, Johanne; Höskuldsson, Ármann; Holm, Paul Martin; Larsen, Guðrún

2018-04-01

Katla volcano in Iceland produces hazardous large explosive basaltic eruptions on a regular basis, but very little quantitative data for future hazard assessments exist. Here details on fragmentation mechanism and eruption dynamics are derived from a study of deposit stratigraphy with detailed granulometry and grain morphology analysis, granulometric modeling, componentry and the new quantitative regularity index model of fragmentation mechanism. We show that magma/water interaction is important in the ash generation process, but to a variable extent. By investigating the large explosive basaltic eruptions from 1755 and 1625, we document that eruptions of similar size and magma geochemistry can have very different fragmentation dynamics. Our models show that fragmentation in the 1755 eruption was a combination of magmatic degassing and magma/water-interaction with the most magma/water-interaction at the beginning of the eruption. The fragmentation of the 1625 eruption was initially also a combination of both magmatic and phreatomagmatic processes, but magma/water-interaction diminished progressively during the later stages of the eruption. However, intense magma/water interaction was reintroduced during the final stages of the eruption dominating the fine fragmentation at the end. This detailed study of fragmentation changes documents that subglacial eruptions have highly variable interaction with the melt water showing that the amount and access to melt water changes significantly during eruptions. While it is often difficult to reconstruct the progression of eruptions that have no quantitative observational record, this study shows that integrating field observations and granulometry with the new regularity index can form a coherent model of eruption evolution.

Primative components, crustal assimilation, and magmatic degassing of the 2008 Kilauea summit eruption

Science.gov (United States)

Rowe, Michael C.; Thornber, Carl R.; Orr, Tim R.

2015-01-01

Simultaneous summit and rift zone eruptions at Kīlauea starting in 2008 reflect a shallow eruptive plumbing system inundated by a bourgeoning supply of new magma from depth. Olivine-hosted melt inclusions, host glass, and bulk lava compositions of magma erupted at both the summit and east rift zone demonstrate chemical continuity at both ends of a well-worn summit-to-rift pipeline. Analysis of glass within dense-cored lapilli erupted from the summit in March – August 2008 show these are not samplings of compositionally distinct magmas stored in the shallow summit magma reservoir, but instead result from remelting and assimilation of fragments from conduit wall and vent blocks. Summit pyroclasts show the predominant and most primitive component erupted to be a homogenous, relatively trace-element-depleted melt that is a compositionally indistinguishable from east rift lava. Based on a “top-down” model for the geochemical variation in east rift zone lava over the past 30 years, we suggest that the apparent absence of a 1982 enriched component in melt inclusions, as well as the proposed summit-rift zone connectivity based on sulfur and mineral chemistry, indicate that the last of the pre-1983 magma has been flushed out of the summit reservoir during the surge of mantle-derived magma from 2003-2007.

Thermal induced EPR signals in tooth enamel

International Nuclear Information System (INIS)

Fattibene, P.; Aragno, D.; Onori, S.; Pressello, M.C.

2000-01-01

Electron paramagnetic resonance (EPR) spectroscopy was used to detect the effects of temperature on powdered human tooth enamel, not irradiated in the laboratory. Samples were heated at temperature between 350 and 450, at 600 and at 1000 deg. C, for different heating times, between 6 min and 39 h. Changes in the EPR spectra were detected, with the formation of new signals. Possible correlation between the changes in EPR spectra and modifications in the enamel and in the mineral phase of bone detected with other techniques is discussed. The implications for dosimetric applications of signals induced by overheating due to mechanical friction during sample preparation are underlined

Regenerative treatment of an immature, traumatized tooth with apical periodontitis: report of a case.

Science.gov (United States)

Cotti, Elisabetta; Mereu, Manuela; Lusso, Daniela

2008-05-01

This case report describes the treatment of a necrotic immature permanent central incisor with complete crown fracture, suspected root fracture, and sinus tract, which was not treated with conventional apexification techniques. Instead, a regenerative approach based on the trauma literature's methods for revascularization was provided. The root canal was gently debrided of necrotic tissue with a sharp spoon excavator and irrigated for only one third of its length with NaOCl and then medicated with calcium hydroxide. After 15 days the sinus tract had healed, and the tooth was asymptomatic. The tooth was accessed, calcium hydroxide was removed, bleeding was stimulated to form an intracanal blood clot, and mineral trioxide aggregate was placed coronally to the blood clot. After 8 months, a coronal calcified barrier was radiographically evident and accompanied with progressive thickening of the root wall and apical closure. Two and a half years after treatment was initiated, the tooth remained asymptomatic, and the sinus tract had not reappeared. The progressive increase in the thickness of the dentinal walls and subsequent apical development suggest that appropriate biologic responses can occur with this type of treatment of the necrotic immature permanent tooth with sinus tract.

Evaluation of autogenous tooth transplantation for replacement of the missing or unrestorable mandibular molar tooth

Directory of Open Access Journals (Sweden)

Wahiduj Jaman

2017-06-01

Full Text Available This study was undertaken to evaluate the functional and occlusal stability of autogenous tooth transplantation. A total of 30 patients were included. Among them, 21 participants received transplanted first molar and the remaining 9 received transplanted second molar. In all the cases, donor tooth were third molar. In each participant, extraction of un-restorable first or second molar tooth was performed which was then replaced by atrumatic extracted third molar tooth. Each third molar tooth was placed in the recipient extracted socket, followed by the evaluation of the occlusion and then stabilized with arch bar and ligature wire. Clinical follow-up evaluation was performed at 15 days, 3 and 12 months in respect to occlusal stability, tooth mobility and periodontal status. It was found that 23 transplanted tooth were successful and the remaining 7 tooth need long-term observation for the final outcome, which was statistically significant. It can be concluded that the autogenous tooth transplantation can replace missing tooth to ensure the preservation of function, aesthetic and to prevent bone resorption of the missing area of the jaw, which can lead to exceptional esthetic and functional outcome.

The influence of eruption season on the global aerosol evolution and radiative impact of tropical volcanic eruptions

Directory of Open Access Journals (Sweden)

M. Toohey

2011-12-01

Full Text Available Simulations of tropical volcanic eruptions using a general circulation model with coupled aerosol microphysics are used to assess the influence of season of eruption on the aerosol evolution and radiative impacts at the Earth's surface. This analysis is presented for eruptions with SO₂ injection magnitudes of 17 and 700 Tg, the former consistent with estimates of the 1991 Mt. Pinatubo eruption, the later a near-"super eruption". For each eruption magnitude, simulations are performed with eruptions at 15° N, at four equally spaced times of year. Sensitivity to eruption season of aerosol optical depth (AOD, clear-sky and all-sky shortwave (SW radiative flux is quantified by first integrating each field for four years after the eruption, then calculating for each cumulative field the absolute or percent difference between the maximum and minimum response from the four eruption seasons. Eruption season has a significant influence on AOD and clear-sky SW radiative flux anomalies for both eruption magnitudes. The sensitivity to eruption season for both fields is generally weak in the tropics, but increases in the mid- and high latitudes, reaching maximum values of ~75 %. Global mean AOD and clear-sky SW anomalies show sensitivity to eruption season on the order of 15–20 %, which results from differences in aerosol effective radius for the different eruption seasons. Smallest aerosol size and largest cumulative impact result from a January eruption for Pinatubo-magnitude eruption, and from a July eruption for the near-super eruption. In contrast to AOD and clear-sky SW anomalies, all-sky SW anomalies are found to be insensitive to season of eruption for the Pinatubo-magnitude eruption experiment, due to the reflection of solar radiation by clouds in the mid- to high latitudes. However, differences in all-sky SW anomalies between eruptions in different seasons are significant for the larger eruption magnitude, and the ~15 % sensitivity to

Mathematical description of tooth flank surface of globoidal worm gear with straight axial tooth profile

Science.gov (United States)

Połowniak, Piotr; Sobolak, Mariusz

2017-12-01

In this article, a mathematical description of tooth flank surface of the globoidal worm and worm wheel generated by the hourglass worm hob with straight tooth axial profile is presented. The kinematic system of globoidal worm gear is shown. The equation of globoid helix and tooth axial profile of worm is derived to determine worm tooth surface. Based on the equation of meshing the contact lines are obtained. The mathematical description of globoidal worm wheel tooth flank is performed on the basis of contact lines and generating the tooth side by the extreme cutting edge of worm hob. The presented mathematical model of tooth flank of TA worm and worm wheel can be used e.g. to analyse the contact pattern of the gear.

Nonsyndromic tooth agenesis patterns and associated developmental dental anomalies: a literature review with radiographic illustrations.

Science.gov (United States)

Agarwal, P; Vinuth, D P; Dube, G; Dube, P

2013-01-01

Tooth agenesis is one of the most intriguing phenomena, because it is frequently associated with other oral anomalies, structural variations and malformations of other teeth, late eruption, transposition and crowding. The diagnosis can be quite challenging as radiographic examination is critical for the diagnosis but not always possible and the late developing teeth may be sometimes scored developmentally missing. Accurate diagnosis therefore requires radiographic, clinical, and dental cast examinations. It is an important clinical and public health problem. Patients with missing permanent teeth may suffer from a reduced chewing ability, inarticulate pronunciation, and an unfavorable aesthetic appearance. Clinically, early diagnosis of a dental anomaly can alert the clinician to the possible development of other associated dental anomalies in the same patient or family, and avoid the possible sequelae. Understanding of tooth agenesis patterns and their impact on diagnosis, prevention, and eventually therapeutics are becoming integral parts of comprehensive dental care. Dental examination with radiographic screening of hypodontia in early childhood should be emphasized as part of public oral health policy to allow early diagnosis and timely intervention.

Magmatic controls on eruption dynamics of the 1950 yr B.P. eruption of San Antonio Volcano, Tacaná Volcanic Complex, Mexico-Guatemala

Science.gov (United States)

Mora, Juan Carlos; Gardner, James Edward; Macías, José Luis; Meriggi, Lorenzo; Santo, Alba Patrizia

2013-07-01

San Antonio Volcano, in the Tacaná Volcanic Complex, erupted ~ 1950 yr. B.P., with a Pelean type eruption that produced andesitic pyroclastic surges and block-and-ash flows destroying part of the volcano summit and producing a horse-shoe shaped crater open to the SW. Between 1950 and 800 yr B.P. the eruption continued with effusive andesites followed by a dacite lava flow and a summit dome, all from a single magma batch. All products consist of phenocrysts and microphenocrysts of zoned plagioclase, amphibole, pyroxene, magnetite ± ilmenite, set in partially crystallized groundmass of glass and microlites of the same mineral phases, except for the lack of amphibole. Included in the andesitic blocks of the block-and-ash flow deposit are basaltic andesite enclaves with elongated and ellipsoidal forms and chilled margins. The enclaves have intersertal textures with brown glass between microphenocrysts of plagioclase, hornblende, pyroxene, and olivine, and minor proportions of phenocrysts of plagioclase, hornblende, and pyroxene. A compositional range obtained of blocks and enclaves resulted from mixing between andesite (866 °C ± 22) and basaltic andesite (enclaves, 932 °C ± 22), which may have triggered the explosive Pelean eruption. Vestiges of that mixing are preserved as complex compositional zones in plagioclase and clinopyroxene-rich reaction rims in amphibole in the andesite. Whole-rock chemistry, geothermometry, experimental petrology and modeling results suggest that after the mixing event the eruption tapped hybrid andesitic magma (≤ 900 °C) and ended with effusive dacitic magma (~ 825 °C), all of which were stored at ~ 200 MPa water pressure. A complex open-system evolution that involved crustal end-members best explains the generation of effusive dacite from the hybrid andesite. Amphibole in the dacite is rimmed by reaction products of plagioclase, orthopyroxene, and Fe-Ti oxides produced by decompression during ascent. Amphibole in the andesite

Tooth - abnormal colors

Science.gov (United States)

... medlineplus.gov/ency/article/003065.htm Tooth - abnormal colors To use the sharing features on this page, please enable JavaScript. Abnormal tooth color is any color other than white to yellowish- ...

Experimental Constraints on Forecasting the Location of Volcanic Eruptions from Pre-eruptive Surface Deformation

Directory of Open Access Journals (Sweden)

Frank Guldstrand

2018-02-01

Full Text Available Volcanic eruptions pose a threat to lives and property when volcano flanks and surroundings are densely populated. The local impact of an eruption depends firstly on its location, whether it occurs near a volcano summit, or down on the flanks. Then forecasting, with a defined accuracy, the location of a potential, imminent eruption would significantly improve the assessment and mitigation of volcanic hazards. Currently, the conventional volcano monitoring methods based on the analysis of surface deformation assesses whether a volcano may erupt but are not implemented to locate imminent eruptions in real time. Here we show how surface deformation induced by ascending eruptive feeders can be used to forecast the eruption location through a simple geometrical analysis. Our analysis builds on the results of 33 scaled laboratory experiments simulating the emplacement of viscous magma intrusions in a brittle, cohesive Coulomb crust under lithostatic stress conditions. The intrusion-induced surface deformation was systematically monitored at high spatial and temporal resolution. In all the experiments, surface deformation preceding the eruptions resulted in systematic uplift, regardless of the intrusion shape. The analysis of the surface deformation patterns leads to the definition of a vector between the center of the uplifted area and the point of maximum uplift, which systematically acted as a precursor to the eruption's location. The temporal evolution of this vector indicated the direction in which the subsequent eruption would occur and ultimately the location itself, irrespective of the feeder shapes. Our findings represent a new approach on how surface deformation on active volcanoes that are not in active rifts could be analysed and used prior to an eruption with a real potential to improve hazard mitigation.

SYMPATHETIC SOLAR FILAMENT ERUPTIONS

Energy Technology Data Exchange (ETDEWEB)

Wang, Rui; Liu, Ying D.; Zimovets, Ivan; Hu, Huidong; Yang, Zhongwei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Dai, Xinghua, E-mail: liuxying@spaceweather.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2016-08-10

The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.

Ultrastructural and immunocytochemical characterization of ameloblast-enamel adhesion at maturation stage in amelogenesis in Macaca fuscata tooth germ.

Science.gov (United States)

Sawada, Takashi

2015-12-01

Maturation-stage ameloblasts are firmly bound to the tooth enamel by a basal lamina-like structure. The mechanism underlying this adhesion, however, remains to be fully clarified. The goal of this study was to investigate the mechanism underlying adhesion between the basal lamina-like structure and the enamel in monkey tooth germ. High-resolution immunogold labeling was performed to localize amelotin and laminin 332 at the interface between ameloblasts and tooth enamel. Minute, electron-dense strands were observed on the enamel side of the lamina densa, extending into the degrading enamel matrix to produce a well-developed fibrous layer (lamina fibroreticularis). In un-demineralized tissue sections, mineral crystals smaller than those in the bulk of the enamel were observed adhering to these strands where they protruded into the surface enamel. Immunogold particles reactive for amelotin were preferentially localized on these strands in the fibrous layer. On the other hand, those for laminin 332 were localized solely in the lamina densa; none were observed in the fibrous layer. These results suggest that the fibrous layer of the basal lamina-like structure is partly composed of amelotin molecules, and that these molecules facilitate ameloblast-enamel adhesion by promoting mineralization of the fibrous layer during the maturation stage of amelogenesis.

Magma viscosity estimation based on analysis of erupted products. Potential assessment for large-scale pyroclastic eruptions

International Nuclear Information System (INIS)

Takeuchi, Shingo

2010-01-01

After the formulation of guidelines for volcanic hazards in site evaluation for nuclear installations (e.g. JEAG4625-2009), it is required to establish appropriate methods to assess potential of large-scale pyroclastic eruptions at long-dormant volcanoes, which is one of the most hazardous volcanic phenomena on the safety of the installations. In considering the volcanic dormancy, magma eruptability is an important concept. The magma eruptability is dominantly controlled by magma viscosity, which can be estimated from petrological analysis of erupted materials. Therefore, viscosity estimation of magmas erupted in past eruptions should provide important information to assess future activities at hazardous volcanoes. In order to show the importance of magma viscosity in the concept of magma eruptability, this report overviews dike propagation processes from a magma chamber and nature of magma viscosity. Magma viscosity at pre-eruptive conditions of magma chambers were compiled based on previous petrological studies on past eruptions in Japan. There are only 16 examples of eruptions at 9 volcanoes satisfying data requirement for magma viscosity estimation. Estimated magma viscosities range from 10 2 to 10 7 Pa·s for basaltic to rhyolitic magmas. Most of examples fall below dike propagation limit of magma viscosity (ca. 10 6 Pa·s) estimated based on a dike propagation model. Highly viscous magmas (ca. 10 7 Pa·s) than the dike propagation limit are considered to lose eruptability which is the ability to form dikes and initiate eruptions. However, in some cases, small precursory eruptions of less viscous magmas commonly occurred just before climactic eruptions of the highly viscous magmas, suggesting that the precursory dike propagation by the less viscous magmas induced the following eruptions of highly viscous magmas (ca. 10 7 Pa·s). (author)

The source and longevity of sulfur in an Icelandic flood basalt eruption plume

Science.gov (United States)

Ilyinskaya, Evgenia; Edmonds, Marie; Mather, Tamsin; Schmidt, Anja; Hartley, Margaret; Oppenheimer, Clive; Pope, Francis; Donovan, Amy; Sigmarsson, Olgeir; Maclennan, John; Shorttle, Oliver; Francis, Peter; Bergsson, Baldur; Barsotti, Sara; Thordarson, Thorvaldur; Bali, Eniko; Keller, Nicole; Stefansson, Andri

2015-04-01

chalcophile metals through the melt and the volcanic plume. By combining petrological analysis, in-plume sampling of gases and aerosol, and plume dispersion modelling, we will address two principal research objectives related to understanding the sulfur systematics of the eruption: (1) To examine the sulfur budget as recorded in the erupted rocks in the form of dissolved sulfur and sulfide minerals, which break down on eruption and (2) To investigate the SO2 lifetime in the atmosphere, by measurements in the both young and ageing eruption plume and plume dispersion modelling In addition we will analyse the characteristics of the aerosol mass necessary for health impact assessment. We will carry out two field campaigns, in January 2015 (short daylight) and, if the eruption is still ongoing, in April 2015 (long daylight). Here we present the first results of our project following the winter campaign.

Precise chronology of differentiation of developing human primary dentition.

Science.gov (United States)

Hu, Xuefeng; Xu, Shan; Lin, Chensheng; Zhang, Lishan; Chen, YiPing; Zhang, Yanding

2014-02-01

While correlation of developmental stage with embryonic age of the human primary dentition has been well documented, the available information regarding the differentiation timing of the primary teeth was largely based on the observation of initial mineralization and varies significantly. In this study, we aimed to document precise differentiation timing of the developing human primary dentition. We systematically examined the expression of odontogenic differentiation markers along with the formation of mineralized tissue in each developing maxillary and mandibular teeth from human embryos with well-defined embryonic age. We show that, despite that all primary teeth initiate development at the same time, odontogenic differentiation begins in the maxillary incisors at the 15th week and in the mandibular incisors at the 16th week of gestation, followed by the canine, the first primary premolar, and the second primary premolar at a week interval sequentially. Despite that the mandibular primary incisors erupt earlier than the maxillary incisors, this distal to proximal sequential differentiation of the human primary dentition coincides in general with the sequence of tooth eruption. Our results provide an accurate chronology of odontogenic differentiation of the developing human primary dentition, which could be used as reference for future studies of human tooth development.

Experimental constraints on forecasting the location of volcanic eruptions from pre-eruptive surface deformation

Science.gov (United States)

Guldstrand, Frank; Galland, Olivier; Hallot, Erwan; Burchardt, Steffi

2018-02-01

Volcanic eruptions pose a threat to lives and property when volcano flanks and surroundings are densely populated. The local impact of an eruption depends firstly on its location, whether it occurs near a volcano summit, or down on the flanks. Then forecasting, with a defined accuracy, the location of a potential, imminent eruption would significantly improve the assessment and mitigation of volcanic hazards. Currently, the conventional volcano monitoring methods based on the analysis of surface deformation assesses whether a volcano may erupt but are not implemented to locate imminent eruptions in real time. Here we show how surface deformation induced by ascending eruptive feeders can be used to forecast the eruption location through a simple geometrical analysis. Our analysis builds on the results of 33 scaled laboratory experiments simulating magma intrusions in a brittle crust, during which the intrusion-induced surface deformation was systematically monitored at high spatial and temporal resolution. In all the experiments, surface deformation preceding the eruptions resulted in systematic uplift, regardless of the intrusion shape. The analysis of the surface deformation patterns leads to the definition of a vector between the centre of the uplifted zone and the point of maximum uplift, which systematically acted as a precursor to the eruption’s location. The temporal evolution of this vector indicated the direction in which the subsequent eruption would occur and ultimately the location itself, irrespective of the feeder shapes. Our findings represent a new approach on how surface deformation on active volcanoes could be analysed and used prior to an eruption with a real potential to improve hazard mitigation.

Prevalence and distribution of dental anomalies: a comparison between maxillary and mandibular tooth agenesis.

Science.gov (United States)

Al-Abdallah, Mariam; AlHadidi, Abeer; Hammad, Mohammad; Al-Ahmad, Hazem; Saleh, Raja'

2015-11-01

The aim of this study was to compare the pattern and prevalence of associated dental anomalies between maxillary and mandibular tooth agenesis (hypodontia). A sample of 3315 dental patients, aged 8.6 to 25.4 years, was surveyed for tooth agenesis (excluding third molars): 106 subjects were diagnosed with maxillary hypodontia (group 1) and 70 with mandibular hypodontia (group 2). Both groups were examined for the following dental anomalies: retained deciduous molars, infraocclusion of deciduous molars, impaction, microdontia of maxillary lateral incisors, supernumerary teeth, transposition, transmigration, and ectopic eruption of the permanent molars. For statistical testing, the chi-square test (P anomalies among the groups. We found that 77.5% of the patients in the mandibular hypodontia group had at least 1 dental anomaly compared with 49.5% in the maxillary hypodontia group (P dental anomaly with a significantly increased prevalence in the maxillary hypodontia group compared with the mandibular hypodontia group was microdontia of the maxillary lateral incisors (groups 1, 46.7%; group 2, 12.9%; P dental development in both jaws. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Eruption and degassing dynamics of the major August 2015 Piton de la Fournaise eruption

Science.gov (United States)

Di Muro, Andrea; Arellano, Santiago; Aiuppa, Alessandro; Bachelery, Patrick; Boudoire, Guillaume; Coppola, Diego; Ferrazzini, Valerie; Galle, Bo; Giudice, Gaetano; Gurioli, Lucia; Harris, Andy; Liuzzo, Marco; Metrich, Nicole; Moune, Severine; Peltier, Aline; Villeneuve, Nicolas; Vlastelic, Ivan

2016-04-01

Piton de la Fournaise (PdF) shield volcano is one of the most active basaltic volcanoes in the World with one eruption every nine months, on average. This frequent volcanic activity is broadly bimodal, with frequent small volume, short lived eruptions (de la Fournaise volcanological observatory (DOAS, MultiGaS, diffuse CO2 soil emissions). Regular lava and tephra sampling was also performed for geochemical and petrological analysis. The eruption was preceded by a significant increase in CO2 soil emissions at distal soil stations (ca. 15 km from the summit), with CO2 enrichment also being recorded at summit low temperature fumaroles. Eruptive products were spectacularly zoned, with plagioclase and pyroxene being abundant in the early erupted products and olivine being the main phase in the late-erupted lavas. Total gas emissions at the eruptive vent underwent a decrease during the first half of the eruption and then an increase, mirroring the time evolution of magma discharge rate (from 5-10 m3/s in September to 15-30 m3/s in late-October) and the progressive change in magma composition. In spite of significant evolution in magma and gas output, CO2/SO2 ratios in high temperature gases remained quite low (< 0.3) and with little temporal change. Geochemical data indicated that this relatively long-lived eruption corresponded to the progressive drainage of most of the shallow part of PdF plumbing system, triggered by a new pulse of deep magma. While erupted magma and high temperature gases were mostly provided by the shallow part of the system, distal sites and summit low temperature fumaroles recorded a deeper triggering mechanism.

Het belang van mineraalsuppletie voor gebit en kaak [The importance of mineral supplementation for dentition and jaw

NARCIS (Netherlands)

Theuns, H.M.

1995-01-01

In this article the importance of mineral suppletion for teeth and jawbone is explained in a step-wise manner. The steps discussed are the pre-eruptive phase of teeth and the growth, adult and ageing phase of the skeleton. Mineral suppletion should be seen as a measure to prevent dental caries

Mechanism of Calcite Co-Orientation in the Sea Urchin Tooth

Energy Technology Data Exchange (ETDEWEB)

Killian, Christopher; Metzler, Rebecca; Gong, Y. U. T.; Olson, Ian; Aizenberg, Joanna; Politi, Yael; Wilt, Fred; Scholl, Andreas; Young, Anthony; Doran, Andrew; Kunz, Martin; Tamura, Nobumichi; Coppersmith, Susan; Gilbert, P. U. P. A.

2009-12-01

Sea urchin teeth are remarkable and complex calcite structures, continuously growing at the forming end and self-sharpening at the mature grinding tip. The calcite (CaCO{sub 3}) crystals of tooth components, plates, fibers, and a high-Mg polycrystalline matrix, have highly co-oriented crystallographic axes. This ability to co-orient calcite in a mineralized structure is shared by all echinoderms. However, the physico-chemical mechanism by which calcite crystals become co-oriented in echinoderms remains enigmatic. Here, we show differences in calcite c-axis orientations in the tooth of the purple sea urchin (Strongylocentrotus purpuratus), using high-resolution X-ray photoelectron emission spectromicroscopy (X-PEEM) and microbeam X-ray diffraction ({mu}XRD). All plates share one crystal orientation, propagated through pillar bridges, while fibers and polycrystalline matrix share another orientation. Furthermore, in the forming end of the tooth, we observe that CaCO{sub 3} is present as amorphous calcium carbonate (ACC). We demonstrate that co-orientation of the nanoparticles in the polycrystalline matrix occurs via solid-state secondary nucleation, propagating out from the previously formed fibers and plates, into the amorphous precursor nanoparticles. Because amorphous precursors were observed in diverse biominerals, solid-state secondary nucleation is likely to be a general mechanism for the co-orientation of biomineral components in organisms from different phyla.

Revascularization procedure in an open apex tooth with external root resorption: A case report

Directory of Open Access Journals (Sweden)

Mahsa Dastpak

2017-06-01

Full Text Available External inflammatory root resorption (EIR represents a challenge in endodontic practice. EIR commonly occurs after dental trauma that results in periodontal ligament injury, pulp necrosis and subsequent infection.  Treatment of EIR is based on disinfecting the root canal system through chemomechanical procedures and then filling it with calcium hydroxide or triple antibiotic paste. Dental trauma commonly occurs in young patients whose teeth are not fully formed and have thin dentinal walls and open apices. Revascularization therapy has proven to be suitable for treatment of root canals of teeth with pulp necrosis and open apices. This case report presents successful revascularization treatment of a permanent immature tooth with external root resorption and chronic apical periodontitis. The tooth was treated by the protocol suggested by the American Association of Endodontics (AAE, consisted of disinfecting the root canal system, filling it with blood clot and sealing the root canal with mineral trioxide aggregate followed by bonded resin restoration. The symptoms disappeared, the size of the periapical lesion reduced and the tooth was asymptomatic during the 12 month follow up period.

The eruptive chronology of the Ampato-Sabancaya volcanic complex (Southern Peru)

Science.gov (United States)

Samaniego, Pablo; Rivera, Marco; Mariño, Jersy; Guillou, Hervé; Liorzou, Céline; Zerathe, Swann; Delgado, Rosmery; Valderrama, Patricio; Scao, Vincent

2016-09-01

We have reconstructed the eruptive chronology of the Ampato-Sabancaya volcanic complex (Southern Peru) on the basis of extensive fieldwork, and a large dataset of geochronological (40K-40Ar, 14C and 3He) and geochemical (major and trace element) data. This volcanic complex is composed of two successive edifices that have experienced discontinuous volcanic activity from Middle Pleistocene to Holocene times. The Ampato compound volcano consists of a basal edifice constructed over at least two cone-building stages dated at 450-400 ka and 230-200 ka. After a period of quiescence, the Ampato Upper edifice was constructed firstly during an effusive stage (80-70 ka), and then by the formation of three successive peaks: the Northern, Southern (40-20 ka) and Central cones (20-10 ka). The Southern peak, which is the biggest, experienced large explosive phases, resulting in deposits such as the Corinta plinian fallout. During the Holocene, eruptive activity migrated to the NE and constructed the mostly effusive Sabancaya edifice. This cone comprised many andesitic and dacitic blocky lava flows and a young terminal cone, mostly composed of pyroclastic material. Most samples from the Ampato-Sabancaya define a broad high-K magmatic trend composed of andesites and dacites with a mineral assemblage of plagioclase, amphibole, biotite, ortho- and clino-pyroxene, and Fe-Ti oxides. A secondary trend also exists, corresponding to rare dacitic explosive eruptions (i.e. Corinta fallout and flow deposits). Both magmatic trends are derived by fractional crystallisation involving an amphibole-rich cumulate with variable amounts of upper crustal assimilation. A marked change in the overall eruptive rate has been identified between Ampato ( 0.1 km3/ka) and Sabancaya (0.6-1.7 km3/ka). This abrupt change demonstrates that eruptive rates have not been homogeneous throughout the volcano's history. Based on tephrochronologic studies, the Late Holocene Sabancaya activity is characterised by strong

Nicotinic Receptor Alpha7 Expression during Tooth Morphogenesis Reveals Functional Pleiotropy

Science.gov (United States)

Rogers, Scott W.; Gahring, Lorise C.

2012-01-01

The expression of nicotinic acetylcholine receptor (nAChR) subtype, alpha7, was investigated in the developing teeth of mice that were modified through homologous recombination to express a bi-cistronic IRES-driven tau-enhanced green fluorescent protein (GFP); alpha7GFP) or IRES-Cre (alpha7Cre). The expression of alpha7GFP was detected first in cells of the condensing mesenchyme at embryonic (E) day E13.5 where it intensifies through E14.5. This expression ends abruptly at E15.5, but was again observed in ameloblasts of incisors at E16.5 or molar ameloblasts by E17.5–E18.5. This expression remains detectable until molar enamel deposition is completed or throughout life as in the constantly erupting mouse incisors. The expression of alpha7GFP also identifies all stages of innervation of the tooth organ. Ablation of the alpha7-cell lineage using a conditional alpha7Cre×ROSA26-LoxP(diphtheria toxin A) strategy substantially reduced the mesenchyme and this corresponded with excessive epithelium overgrowth consistent with an instructive role by these cells during ectoderm patterning. However, alpha7knock-out (KO) mice exhibited normal tooth size and shape indicating that under normal conditions alpha7 expression is dispensable to this process. The function of ameloblasts in alpha7KO mice is altered relative to controls. High resolution micro-computed tomography analysis of adult mandibular incisors revealed enamel volume of the alpha7KO was significantly reduced and the organization of enamel rods was altered relative to controls. These results demonstrate distinct and varied spatiotemporal expression of alpha7 during tooth development, and they suggest that dysfunction of this receptor would have diverse impacts upon the adult organ. PMID:22666322

Prenatal ultrasound and postmortem histologic evaluation of tooth germs: an observational, transversal study.

Science.gov (United States)

Seabra, Mariana; Felino, António; Nogueira, Rosete; Valente, Francisco; Braga, Ana Cristina; Vaz, Paula

2015-05-12

Hypodontia is the most frequent developmental anomaly of the orofacial complex, and its detection in prenatal ultrasound may indicate the presence of congenital malformations, genetic syndromes and chromosomal abnormalities. To date, only a few studies have evaluated the histological relationship of human tooth germs identified by two-dimensional (2D) ultrasonography. In order to analyze whether two-dimensional ultrasonography of tooth germs may be successfully used for identifying genetic syndromes, prenatal ultrasound images of fetal tooth germs obtained from a Portuguese population sample were compared with histological images obtained from fetal autopsies. Observational, descriptive, transversal study. The study protocol followed the ethical principles outlined by the Helsinki Declaration and was approved by the Ethics Committee of the School of Dental Medicine, University of Porto (FMDUP, Porto, Portugal) and of the Centro Hospitalar de Vila Nova de Gaia/Espinho (CHVNG/EPE, Porto, Portugal) as well as by the CGC Genetics Embryofetal Pathology Laboratory. Eighty-five fetuses examined by prenatal ultrasound screening from May 2011 to August 2012 had an indication for autopsy following spontaneous fetal death or medical termination of pregnancy. Of the 85 fetuses, 37 (43.5%) were randomly selected for tooth germ evaluation by routine histopathological analysis. Fetuses who were up to 30 weeks of gestation, and whose histological pieces were not representative of all maxillary tooth germs was excluded. Twenty four fetus between the 13(th) and 30(th) weeks of gestation fulfilled the parameters to autopsy. Twenty four fetuses were submitted to histological evaluation and were determined the exact number, morphology, and mineralization of their tooth germs. All tooth germs were identifiable with ultrasonography as early as the 13(th) week of gestation. Of the fetuses autopsied, 41.7% had hypodontia (29.1% maxillary hypodontia and 20.9% mandibular hypodontia). This

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

Science.gov (United States)

Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

International Nuclear Information System (INIS)

Jiang, Chao-Wei; Feng, Xue-Shang; Wu, Shi-Tsan; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE–MHD–NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption. (paper)

Orthodontic Tooth Movement: A Historic Prospective.

Science.gov (United States)

Will, Leslie A

2016-01-01

The earliest report on orthodontic tooth movement in the English literature was published in 1911. Oppenheim carried out studies on baboons to determine what histologic changes occurred during tooth movement. Reitan and many others carried out research into the nature of tooth movement. The pressure-tension model of tooth movement developed from these studies, whereby the two sides of the tooth responded to forces as if in isolation. A second theory, proposed by Stuteville in 1938, was the hydraulic theory of tooth movement. In this theory, fluid from the vasculature, lymphatic system and intercellular spaces responds to the forces of tooth movement, damping the force and limiting movement. Bien and Baumrind expanded on this theory with their own studies in the 1960s. It is clear that both the pressure-tension and fluid flow concepts have merit, but considerable work needs to be done to ascertain the details so that tooth movement can be managed and controlled. © 2016 S. Karger AG, Basel.

Comparative temporospatial expression profiling of murine amelotin protein during amelogenesis.

Science.gov (United States)

Somogyi-Ganss, Eszter; Nakayama, Yohei; Iwasaki, Kengo; Nakano, Yukiko; Stolf, Daiana; McKee, Marc D; Ganss, Bernhard

2012-01-01

Tooth enamel is formed in a typical biomineralization process under the guidance of specific organic components. Amelotin (AMTN) is a recently identified, secreted protein that is transcribed predominantly during the maturation stage of enamel formation, but its protein expression profile throughout amelogenesis has not been described in detail. The main objective of this study was to define the spatiotemporal expression profile of AMTN during tooth development in comparison with other known enamel proteins. A peptide antibody against AMTN was raised in rabbits, affinity purified and used for immunohistochemical analyses on sagittal and transverse paraffin sections of decalcified mouse hemimandibles. The localization of AMTN was compared to that of known enamel proteins amelogenin, ameloblastin, enamelin, odontogenic ameloblast-associated/amyloid in Pindborg tumors and kallikrein 4. Three-dimensional images of AMTN localization in molars at selected ages were reconstructed from serial stained sections, and transmission electron microscopy was used for ultrastructural localization of AMTN. AMTN was detected in ameloblasts of molars in a transient fashion, declining at the time of tooth eruption. Prominent expression in maturation stage ameloblasts of the continuously erupting incisor persisted into adulthood. In contrast, amelogenin, ameloblastin and enamelin were predominantly found during the early secretory stage, while odontogenic ameloblast-associated/amyloid in Pindborg tumors and kallikrein 4 expression in maturation stage ameloblasts paralleled that of AMTN. Secreted AMTN was detected at the interface between ameloblasts and the mineralized enamel. Recombinant AMTN protein did not mediate cell attachment in vitro. These results suggest a primary role for AMTN in the late stages of enamel mineralization. Copyright © 2011 S. Karger AG, Basel.

Relationship between eruption plume heights and seismic source amplitudes of eruption tremors and explosion events

Science.gov (United States)

Mori, A.; Kumagai, H.

2016-12-01

It is crucial to analyze and interpret eruption tremors and explosion events for estimating eruption size and understanding eruption phenomena. Kumagai et al. (EPS, 2015) estimated the seismic source amplitudes (As) and cumulative source amplitudes (Is) for eruption tremors and explosion events at Tungurahua, Ecuador, by the amplitude source location (ASL) method based on the assumption of isotropic S-wave radiation in a high-frequency band (5-10 Hz). They found scaling relations between As and Is for eruption tremors and explosion events. However, the universality of these relations is yet to be verified, and the physical meanings of As and Is are not clear. In this study, we analyzed the relations between As and Is for eruption tremors and explosion events at active volcanoes in Japan, and estimated As and Is by the ASL method. We obtained power-law relations between As and Is, in which the powers were different between eruption tremors and explosion events. These relations were consistent with the scaling relations at Tungurahua volcano. Then, we compared As with maximum eruption plume heights (H) during eruption tremors analyzed in this study, and found that H was proportional to 0.21 power of As. This relation is similar to the plume height model based on the physical process of plume rise, which indicates that H is proportional to 0.25 power of volumetric flow rate for plinian eruptions. This suggests that As may correspond to volumetric flow rate. If we assume a seismic source with volume changes and far-field S-wave, As is proportional to the source volume rate. This proportional relation and the plume height model give rise to the relation that H is proportional to 0.25 power of As. These results suggest that we may be able to estimate plume heights in realtime by estimating As during eruptions from seismic observations.

Orthodontic management of buccally erupted ectopic canine with two case reports

Directory of Open Access Journals (Sweden)

Avesh Sachan

2012-01-01

Full Text Available Ectopic canine teeth develop displaced from their normal position. Any permanent tooth can be ectopic, and the cause may be both genetic and environmental. Orthodontic treatment is justified because ectopic canine teeth can migrate in the jaw bone and may damage the adjacent teeth roots and bone. Orthodontic treatment is also justifiable for aesthetic reasons. Diagnosis and treatment of ectopically erupting permanent maxillary canines requires timely management by the orthodontist. Internal or external root resorption of teeth adjacent to the ectopic canine is the most common sequel. Malocclusion with severe crowding is difficult to treat without extraction. Non-extraction treatment of ectopic canines can compromise the patient′s profile. This article represents two cases of extraction treatment approach for buccally displaced or ectopic canine in a patient with severe crowding in the mandibular arch.

Co-eruptive subsidence and post-eruptive uplift associated with the 2011-2012 eruption of Puyehue-Cordón Caulle, Chile, revealed by DInSAR

Science.gov (United States)

Euillades, Pablo Andrés; Euillades, Leonardo Daniel; Blanco, Mauro Hugo; Velez, María Laura; Grosse, Pablo; Sosa, Gustavo Javier

2017-09-01

The 2011-2012 eruption of the Puyehue-Cordón Caulle volcanic complex, southern Andes (Chile), was associated with complex surface deformation affecting an area of roughly 50 by 50 km. We report here differential SAR interferometry (DInSAR) results of pre-, co- and post-eruptive deformation from ENVISAT ASAR, COSMO-Skymed, and ALOS-2/PALSAR scenes acquired between early 2011 and early 2017. No clear pre-eruptive deformation is observed during five months before the eruption, although some patterns could be interpreted as showing inflation occurring between April and May 2011. Co-eruptive interferograms show a complex deformation pattern consisting in a major deflation lobe (120 cm LOS lengthening) centered 10 km NW of the eruption vent accompanied by smaller uplift and subsidence regions in the vicinity of the vent. Re-inflation began immediately after the end of the eruption. A first pulse lasted 3 years between 2012 and 2015, accumulating 70 cm uplift. We detect here a second pulse, beginning in June 2016 and still ongoing in February 2017, reaching 12 cm in half a year. Inverse modeling with spherical cavity and spheroidal sources locates re-inflation sources at a depth ranging between 8 and 11 km under the surface. It suggests re-filling of the reservoir occurring after the draining of a shallow magma chamber during the 2011-2012 eruption.

Premature dental eruption: report of case.

LENUS (Irish Health Repository)

McNamara, C M

2011-08-05

This case report reviews the variability of dental eruption and the possible sequelae. Dental eruption of the permanent teeth in cleft palate children may be variable, with delayed eruption the most common phenomenon. A case of premature dental eruption of a maxillary left first premolar is demonstrated, however, in a five-year-old male. This localized premature dental eruption anomaly was attributed to early extraction of the primary dentition, due to caries.

Tooth wear and feeding ecology in mountain gorillas from Volcanoes National Park, Rwanda.

Science.gov (United States)

Galbany, Jordi; Imanizabayo, Olive; Romero, Alejandro; Vecellio, Veronica; Glowacka, Halszka; Cranfield, Michael R; Bromage, Timothy G; Mudakikwa, Antoine; Stoinski, Tara S; McFarlin, Shannon C

2016-03-01

Ecological factors have a dramatic effect on tooth wear in primates, although it remains unclear how individual age contributes to functional crown morphology. The aim of this study is to determine how age and individual diet are related to tooth wear in wild mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda. We calculated the percent of dentine exposure (PDE) for all permanent molars (M1-M3) of known-age mountain gorillas (N = 23), to test whether PDE varied with age using regression analysis. For each molar position, we also performed stepwise multiple linear regression to test the effects of age and percentage of time spent feeding on different food categories on PDE, for individuals subject to long-term observational studies by the Dian Fossey Gorilla Fund International's Karisoke Research Center. PDE increased significantly with age for both sexes in all molars. Moreover, a significant effect of gritty plant root consumption on PDE was found among individuals. Our results support prior reports indicating reduced tooth wear in mountain gorillas compared to western gorillas, and compared to other known-aged samples of primate taxa from forest and savanna habitats. Our findings corroborate that mountain gorillas present very low molar wear, and support the hypothesis that age and the consumption of particular food types, namely roots, are significant determinants of tooth wear variation in mountain gorillas. Future research should characterize the mineral composition of the soil in the Virunga habitat, to test the hypothesis that the physical and abrasive properties of gritty foods such as roots influence intra- and interspecific patterns of tooth wear. © 2015 Wiley Periodicals, Inc.

Ptychographic X-ray nanotomography quantifies mineral distributions in human dentine

Science.gov (United States)

Zanette, I.; Enders, B.; Dierolf, M.; Thibault, P.; Gradl, R.; Diaz, A.; Guizar-Sicairos, M.; Menzel, A.; Pfeiffer, F.; Zaslansky, P.

2015-03-01

Bones are bio-composites with biologically tunable mechanical properties, where a polymer matrix of nanofibrillar collagen is reinforced by apatite mineral crystals. Some bones, such as antler, form and change rapidly, while other bone tissues, such as human tooth dentine, develop slowly and maintain constant composition and architecture for entire lifetimes. When studying apatite mineral microarchitecture, mineral distributions or mineralization activity of bone-forming cells, representative samples of tissue are best studied at submicrometre resolution while minimizing sample-preparation damage. Here, we demonstrate the power of ptychographic X-ray tomography to map variations in the mineral content distribution in three dimensions and at the nanometre scale. Using this non-destructive method, we observe nanostructures surrounding hollow tracts that exist in human dentine forming dentinal tubules. We reveal unprecedented quantitative details of the ultrastructure clearly revealing the spatially varying mineralization density. Such information is essential for understanding a variety of natural and therapeutic effects for example in bone tissue healing and ageing.

[Assessment of tooth bleaching efficacy with spectrophotometer].

Science.gov (United States)

Zhu, Wenhao; Liu, Chang; Pan, Jie

2014-06-01

To analyze the changes in CIE L*, a*, and b* at cervical, body, and incisal sites after tooth bleaching by using a spectrophotometer. Sixty-seven intact and healthy maxillary central incisors were in-vestigated. These incisors were darker than A3 according to the Vita Classical shade guide. The CIE tooth shade parameters L*, a*, and b* were simultaneously recorded at three tooth areas (cervical, body, and incisal) with a spectrophotometer before and after tooth bleaching (35%H2O2 coordinating with Beyond whitening accelerator irradiating). The shade dif-ferential (DeltaE) was calculated. ANOVA, paired t-test, and Pearson correlation analysis were used for data analysis. The efficacy rates of tooth bleaching were satisfactory, with 86.6%, 86.6%, and 85.1% in the cervical, body, and incisal sites, respectively. The average values of DeltaE were 5.09, 4.44, and 4.40 in the cervical, body, and incisal sites. Tooth bleaching significantly increased L* and significantly decreased a* and b* in all tooth areas (P spectrophotometer could objectively evaluate the whitening effect of tooth bleaching at the different tooth sites. The tooth bleaching system (35%H202 coordinating with Beyond whitening accelerator irradiating) exerts powerful bleaching actions in most of the tooth areas investigated. The order of tooth bleaching effectiveness is cervicalbody>incisal. Yellow coloration is decreased mainly at the cervical site, and brightness was increased mostly at theincisal site. The effectiveness of tooth bleaching increases as the baseline b* value increases.

Prediction of Solar Eruptions Using Filament Metadata

Science.gov (United States)

Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal

2018-05-01

We perform a statistical analysis of erupting and non-erupting solar filaments to determine the properties related to the eruption potential. In order to perform this study, we correlate filament eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK filaments that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each filament instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting filament tracks to discover which properties present signs of an eruption. We find that a change in filament length over time is the most important factor in discriminating between erupting and non-erupting filament tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive filament metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the current metadata is only slightly better than chance.

Overview of Tooth Disorders

Science.gov (United States)

... teeth using a thin resin cement. Bleaching, or tooth whitening, is a process used by dentists to lighten ... following? Damage to only the hard outer surface (enamel) of the tooth An incomplete fracture of a ...

Tooth Wear Is Frequent in Adult Patients with Celiac Disease

Directory of Open Access Journals (Sweden)

Massimo Amato

2017-12-01

Full Text Available (1 Background: Celiac disease (CD patients can be affected by mouth and tooth disorders, which are influenced by their gluten-free diet. The aim of our research was to evaluate the pathological conditions of the stomatognathic system observed in celiac patients on a gluten-free diet. (2 Methods: we consecutively recruited celiac patients on a gluten-free diet at our celiac center, as well as healthy volunteers. Two dentists examined all patients/controls and checked them for any mouth disorder. (3 Results: Forty-nine patients affected by celiac disease (age at test 31.8 ± 11.58, time on GFD 8.73 ± 7.7 and 51 healthy volunteers (age at test 30.5 ± 8.7 were included. Recurrent aphthous stomatitis was reported in 26 patients (53.0% and in 13 (25.5% controls (p = 0.005. Dental enamel disorders were reported in 7 patients (14.3% and in 0 controls (p = 0.002, with none having geographic tongue. We found non-specific tooth wear, characterized by loss of the mineralized tissue of the teeth, in 9 patients (18.3% and in 3 (5.9% controls (p = 0.05. (4 Conclusion: Recurrent aphthous stomatitis and enamel hypoplasia are “risk indicators” that may suggest that an individual has CD. We detected a high prevalence of non-specific tooth wear that can be caused by several factors such as malocclusion, sleep bruxism, parafunctional activity, and age.

The 2006-2009 activity of the Ubinas volcano (Peru): Petrology of the 2006 eruptive products and insights into genesis of andesite magmas, magma recharge and plumbing system

Science.gov (United States)

Rivera, Marco; Thouret, Jean-Claude; Samaniego, Pablo; Le Pennec, Jean-Luc

2014-01-01

Following a fumarolic episode that started six months earlier, the most recent eruptive activity of the Ubinas volcano (south Peru) began on 27 March 2006, intensified between April and October 2006 and slowly declined until December 2009. The chronology of the explosive episode and the extent and composition of the erupted material are documented with an emphasis on ballistic ejecta. A petrological study of the juvenile products allows us to infer the magmatic processes related to the 2006-2009 eruptions of the andesitic Ubinas volcano. The juvenile magma erupted during the 2006 activity shows a homogeneous bulk-rock andesitic composition (56.7-57.6 wt.% SiO2), which belongs to a medium- to high-K calc-alkaline series. The mineral assemblage of the ballistic blocks and tephra consists of plagioclase > two-pyroxenes > Fe-Ti oxide and rare olivine and amphibole set in a groundmass of the same minerals with a dacitic composition (66-67 wt.% SiO2). Thermo-barometric data, based on two-pyroxene and amphibole stability, records a magma temperature of 998 ± 14 °C and a pressure of 476 ± 36 MPa. Widespread mineralogical and textural features point to a disequilibrium process in the erupted andesite magma. These features include inversely zoned "sieve textures" in plagioclase, inversely zoned clinopyroxene, and olivine crystals with reaction and thin overgrowth rims. They indicate that the pre-eruptive magmatic processes were dominated by recharge of a hotter mafic magma into a shallow reservoir, where magma mingling occurred and triggered the eruption. Prior to 2006, a probable recharge of a mafic magma produced strong convection and partial homogenization in the reservoir, as well as a pressure increase and higher magma ascent rate after four years of fumarolic activity. Mafic magmas do not prevail in the Ubinas pre-historical lavas and tephras. However, mafic andesites have been erupted during historical times (e.g. AD 1667 and 2006-2009 vulcanian eruptions). Hence

Serreta 1998-2001 submarine volcanic eruption, offshore Terceira (Azores): Characterization of the vent and inferences about the eruptive dynamics

Science.gov (United States)

Casas, David; Pimentel, Adriano; Pacheco, José; Martorelli, Eleonora; Sposato, Andrea; Ercilla, Gemma; Alonso, Belen; Chiocci, Francesco

2018-05-01

High-resolution bathymetric data and seafloor sampling were used to characterize the most recent volcanic eruption in the Azores region, the 1998-2001 Serreta submarine eruption. The vent of the eruption is proposed to be an asymmetric topographic high, composed of two coalescing volcanic cones, underlying the location where lava balloons had been observed at the sea surface during the eruption. The volcanic products related to the 1998-2001 eruption are constrained to an area of 0.5 km2 around the proposed vent position. A submarine Strombolian-style eruption producing basaltic lava balloons, ash and coarse scoriaceous materials with limited lateral dispersion led to the buildup of the cones. The 1998-2001 Serreta eruption shares many similarities with other intermediate-depth lava balloon-forming eruptions (e.g., the 1891 eruption offshore Pantelleria and the 2011-2012 eruption south of El Hierro), revealing the particular conditions needed for the production of this unusual and scarcely documented volcanic product.

Dental Caries (Tooth Decay)

Science.gov (United States)

... Materials Contact Us Home Research Data & Statistics Dental Caries (Tooth Decay) Dental caries (tooth decay) remains the most prevalent chronic disease ... adults, even though it is largely preventable. Although caries has significantly decreased for most Americans over the ...

Dental Caries (Tooth Decay)

Science.gov (United States)

... Contact Us Home Research Data & Statistics Share Dental Caries (Tooth Decay) Dental caries (tooth decay) remains the most prevalent chronic disease ... adults, even though it is largely preventable. Although caries has significantly decreased for most Americans over the ...

Deposits, petrology and mechanism of the 2010-2013 eruption of Kizimen volcano in Kamchatka, Russia

Science.gov (United States)

Auer, A.; Belousov, A.; Belousova, M.

2018-04-01

Kizimen volcano in Kamchatka is well known as a source of highly heterogeneous poorly mingled magmas ranging from dacites to basaltic andesites. In 2010-2013, the volcano produced its first historical magmatic eruption with the deposition of 0.27 km3 of block and ash pyroclastic flows accompanied by slow extrusion of a 200-m-thick, highly viscous (1010-1011 Pa s) block lava flow with a volume of 0.3 km3. The total volume of erupted magma comprised approximately 0.4 km3 DRE. We provide description of the eruption chronology, as well as the lithology and petrology of eruptive products. The erupted material is represented by banded dacite and high-silica andesite. The dacitic magma was formed during a long dormancy after the previous magmatic eruption several hundred years ago with mineral compositions indicating average pre-eruptive temperatures of 810 °C, fO2 of 0.9-1.6 log units above the nickel-nickel oxide (NNO) buffer and shallow crustal storage conditions at 123 MPa. The silica-rich andesite represents a hybrid magma, which shows signs of recent thermal and compositional disequilibrium. We suggest that the hybrid magma started to form in 1963 when a swarm of deep earthquakes indicated an input of mafic magma from depth into the 6-11-km-deep silicic magma chamber. It took the following 46 years until the magma filling the chamber reached an eruptible state. Poor mingling of the two melts is attributed to its unusually high viscosity that could be associated with the pre-eruptive long-term leakage of volatiles from the chamber through a regional tectonic fault. Our investigations have shown that shallow magma chambers of dormant volcanoes demonstrating strong persistent fumarolic activity can contain highly viscous, degassed magma of evolved composition. Reactivation of such magma chambers by injection of basic magma takes a long time (several decades). Thus, eruption forecasts at such volcanoes should include a possibility of long time lag between a swarm of

Pola Erupsi Gigi Susu dan Gigi Tetap pada Anak Desa IDT Kabupaten Pandeglang dan Serang

Directory of Open Access Journals (Sweden)

Herawati Djoharnas

2015-10-01

Full Text Available Research on deciduous and permanent tooth eruption pattern for children of developing countries is very limited. The aim of this study is to find out, whether there is a difference between tooth eruption of children in developed countries and in Indonesia. For this purpose 456 children under five and 1120 school children with an age of 6 - 15 years were examined. The result showed that the fine of tooth eruption of children in Indonesian is longer than that of children in developed countries.

Io - One of at Least Four Simultaneous Erupting Volcanic Eruptions

Science.gov (United States)

1979-01-01

This photo of an active volcanic eruption on Jupiter's satellite Io was taken 1 hour, 52 minutes after the accompanying picture, late in the evening of March 4, 1979, Pacific time. On the limb of the satellite can be seen one of at least four simultaneous volcanic eruptions -- the first such activity ever observed on another celestial body. Seen against the limb are plume-like structures rising more than 60 miles (100 kilometers) above the surface. Several eruptions have been identified with volcanic structures on the surface of Io, which have also been identified by Voyager 1's infrared instrument as being abnormally hot -- several hundred degrees warmer than surrounding terrain. The fact that several eruptions appear to be occurring at the same time suggests that Io has the most active surface in the solar system and that volcanism is going on there essentially continuously. Another characteristic of the observed volcanism is that it appears to be extremely explosive, with velocities more than 2,000 miles an hour (at least 1 kilometer per second). That is more violent than terrestrial volcanoes like Etna, Vesuvius or Krakatoa.

Development and microstructure of tooth histotypes in the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae) and the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae).

Science.gov (United States)

Moyer, Joshua K; Riccio, Mark L; Bemis, William E

2015-07-01

Elasmobranchs exhibit two distinct arrangements of mineralized tissues in the teeth that are known as orthodont and osteodont histotypes. Traditionally, it has been said that orthodont teeth maintain a pulp cavity throughout tooth development whereas osteodont teeth are filled with osteodentine and lack a pulp cavity when fully developed. We used light microscopy, scanning electron microscopy, and high-resolution micro-computed tomography to compare the structure and development of elasmobranch teeth representing the two histotypes. As an example of the orthodont histotype, we studied teeth of the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae). For the osteodont histotype, we studied teeth of the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae). We document similarities and differences in tooth development and the microstructure of tissues in these two species and review the history of definitions and interpretations of elasmobranch tooth histotypes. We discuss a possible correlation between tooth histotype and tooth replacement and review the history of histotype differentiation in sharks. We find that contrary to a long held misconception, there is no orthodentine in the osteodont teeth of C. carcharias. © 2015 Wiley Periodicals, Inc.

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients.

Science.gov (United States)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-12-01

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Fluoridation and tooth wear in Irish adults.

LENUS (Irish Health Repository)

Burke, F M

2010-10-01

The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

Aging and Fracture of Human Cortical Bone and Tooth Dentin

Energy Technology Data Exchange (ETDEWEB)

Ager, Joel; Koester, Kurt J.; Ager III, Joel W.; Ritchie, Robert O.

2008-05-07

Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms which function primarily behind the tip, such as crack bridging in ceramics. Bone and dentin derive their resistance to fracture principally from extrinsic toughening mechanisms which have their origins in the hierarchical microstructure of these mineralized tissues. Experimentally, quantification of these toughening mechanisms requires a crack-growth resistance approach, which can be achieved by measuring the crack-driving force, e.g., the stress intensity, as a function of crack extension ("R-curve approach"). Here this methodology is used to study of the effect of aging on the fracture properties of human cortical bone and human dentin in order to discern the microstructural origins of toughness in these materials.

Mass Flux of Tephra Sampled Frequently During the Ongoing Halema`uma`u Eruption (Invited)

Science.gov (United States)

Swanson, D.; Wooten, K.; Orr, T. R.

2009-12-01

The ongoing summit eruption of Kilauea provides an unparalleled opportunity to track, almost daily, the production of tephra. The eruption began on 19 March 2008, and tephra has been erupted every day since then to the end of August 2009. Most of the time, tephra is ejected quasi-continuously from the vent accompanied by a light gray to white gas plume, occasionally broken by a more vigorous pulse (“brown plume”) richer in ejecta. In early April 2008, an array of 10 plastic buckets was placed within 400 m of the new vent in Halema`uma`u down the prevailing NE wind direction. The configuration of the array, spanning an area of about 73,000 m2, has not changed since then. Buckets are emptied frequently, initially every day and, since summer 2008, on all weekdays. The contents are dried and weighed, and an “average network accumulation rate” is calculated in g/m2/hour. In addition, componentry analyses are made of the >0.5-mm size fraction from a bucket near the vent, in order to categorize the tephra into juvenile and lithic fractions. To estimate the total mass of tephra ejected from the vent for a given collection, we first drew isomass contours for several daily collections and plotted isomass versus square root of area to obtain the total mass of the deposit. From this, we developed an empirical multiplication factor that allows us to estimate, within ~25 percent, the total ejected mass per day in kilograms from the total collected mass in grams. The tephra is a mix of vitric and lithic pyroclasts, mostly ash in size. The vitric clasts, interpreted as juvenile, include Pele’s hair and tears, hollow spherules, dumbbells, pumice, and bits of coarsely vesicular glass. All these clasts were probably produced by weak spattering at the top of the lava column, which has rarely been seen. Especially since fall 2008, some vitric clasts are partly coated with secondary minerals or rock dust. We interpret such clasts as recycled, first erupted during spattering

Volcanology and hazards of phreatomagmatic basaltic eruptions

DEFF Research Database (Denmark)

Schmith, Johanne

Iceland is one of the most active terrestrial volcanic regions on Earth with an average of more than 20 eruptions per century. Around 80% of all events are tephra generating explosive eruptions, but less than 10 % of all known tephra layers have been mapped. Recent hazard assessment models show...... that the two key parameters for hazard assessment modeling are total grain size distribution (TGSD) and eruptive style. These two parameters have been determined for even fewer eruptive events in Iceland. One of the most hazardous volcanoes in Iceland is Katla and no data set of TGSD or other eruptive...... parameters exist. Katla has not erupted for 99 years, but at least 2 of the 20 eruptions since the settlement of Iceland in 871 have reached Northern Europe as visible tephra fall. These eruptions occurred in 1755 and 1625 and remain enigmatic both in terms of actual size and eruption dynamics. This work...

Thyroid Function during Early Life and Dental Development

NARCIS (Netherlands)

Vucic, S.; Korevaar, T.I.; Dhamo, B.; Jaddoe, V.W.; Peeters, R.P.; Wolvius, E.B.; Ongkosuwito, E.M.

2017-01-01

Children with low levels of thyroid hormones (hypothyroidism) have delayed tooth eruption, enamel hypoplasia, micrognathia, and anterior open bite, whereas children with hyperthyroidism may suffer from accelerated tooth eruption, maxillary, and mandibular osteoporosis. However, it is still unknown

Eruption products of the 1883 eruption of Krakatau and their final settlement

Directory of Open Access Journals (Sweden)

Izumi Yokoyama

2015-06-01

Full Text Available Firstly the volume of pyroclastic ejecta during the 1883 eruption of Krakatau is re-examined. To revise the volume of flow deposits, the author basically follows Verbeek’s observation while to estimate the fall deposits, as the last resort, the author assumes that volume ratios fall / flow are common to similar caldera eruptions, and the ratios determined by the caldera- forming eruptions of Novarupta and Pinatubo are applied to the Krakatau eruption. Verbeek’s estimation of the total volume of ejecta, 12 km3 is revised to 19 km3. This is significantly different from the volume of disrupted volcano edifice, 8 km3. Such a result does not support the predecessors’ hypothesis that calderas are formed by collapses of volcano edifices into magma reservoirs in replacement of the total ejecta. Through the discussion on the volume estimation of volcanic ejecta on and around Krakatau, the author recognizes that such estimation should be originally very difficult to attain enough accuracy. Much importance of “caldera deposits” to post-eruption settlements of the ejecta is emphasized. In relation to caldera formation, mechanical stability of a cavity in the crust is discussed. Lastly, upon the basis of subsurface structure, especially caldera deposits, a structural image of Krakatau caldera is presented.

Contrasting styles of deep-marine pyroclastic eruptions revealed from Axial Seamount push core records

Science.gov (United States)

Portner, Ryan A.; Clague, David A.; Helo, Christoph; Dreyer, Brian M.; Paduan, Jennifer B.

2015-08-01

A comprehensive understanding of explosive basaltic eruption processes in the deep-sea relies upon detailed analysis and comparison of the variety of volcaniclastic lithologies on the seafloor, which has been challenged by insufficient sample recovery. A dedicated ROV-based sampling approach using long push cores offers an unparalleled opportunity to fully characterize the diversity of unconsolidated volcaniclastic lithofacies on a recently active seamount. Lithofacies from Axial Seamount record two styles of pyroclastic eruptions, strombolian and phreatomagmatic, at 1.5 km water depth. Strombolian eruptions are represented by abundant fluidal and highly vesicular (up to 50%) vitriclasts within limu o Pele lapilli tuff and tuffaceous mud lithofacies. Lapilli-ash grain size, normal grading, good sorting, rip-up clasts and homogeneous glass geochemistry characterize individual limu o Pele lapilli tuff beds, and imply proximal deposition from a turbidity flow associated with a single eruption (i.e. event bed). Limu o Pele lapilli tuff beds are interbedded with poorly sorted, chemically heterogeneous and bioturbated tuffaceous mud units that preserve reworking and biologic habitation of more distal pyroclastic fallout and dilute turbidity flows. The phreatomagmatic eruption style is preserved by hydrothermal mineral-bearing muddy tuff that exhibits characteristics distinct from lapilli ash and tuffaceous mud lithofacies. Hydrothermal muddy tuff lithofacies are well-sorted and fine-grained with notable components of non-fluidal basaltic ash (∼45%), fluidal ash (∼30%) and accessory lithics (∼25%). Heterogeneous geochemistry of ash shards implies that juvenile components are minimal. The abundance, mineralogy and texture of lithic components (Fe-Mg clays, pyrite, epidote, actinolite, altered glass, basalt/diabase, hydrothermal breccia and agglutinate), and very fine-grain size of basaltic ash, are consistent with phreatomagmatic eruption deposits. A lack of

Tooth whitening: what we now know.

Science.gov (United States)

Carey, Clifton M

2014-06-01

Current research about tooth whitening shows that it is safe and effective when manufacturer's protocol is followed, yet there are risks of which the profession and users should be aware. This update provides a summary of current research and assessment of the safety and efficacy of tooth whitening regimens. Tooth whitening has become one of the most frequently requested dental procedures by the public. The public has come to demand whiter, more perfect smiles and in response many choices for tooth whitening have been made available. These include home-based products such as toothpastes, gels, and films, as well as in-office based systems where products containing highly concentrated bleaching agents are applied under professional supervision. The profession and public have been aware of certain risks related to tooth whitening such as increased tooth sensitivity and gingival irritation. New research has shown that there are other risks such as tooth surface roughening and softening, increased potential for demineralization, degradation of dental restorations, and unacceptable color change of dental restorations. The new research is also focused on optimizing whitening procedures to reduce tooth sensitivity and to increase the persistence of the whitening. Current reports in the literature are reviewed that are related to the use of peroxide based whitening methods. These reports include in vitro studies for method optimization and mechanism as well as clinical studies on effects of various whitening regimens. When manufacturer's instructions are followed, hydrogen peroxide and carbamide peroxide based tooth whitening is safe and effective. Patients should be informed of the risks associated with tooth whitening and instructed on identification of adverse occurrences so that they may seek professional help as needed. Copyright © 2014 Elsevier Inc. All rights reserved.

Cross correlation of chemical profiles in minerals: insights into the architecture of magmatic reservoirs

Science.gov (United States)

Probst, Line; Caricchi, Luca; Gander, Martin; Wallace, Glenn

2016-04-01

Analysis of chemical zoning in minerals offers the opportunity to reconstruct the pre-eruptive conditions and the temporal evolution of magmatic reservoirs. The chemical composition of minerals is a function of the thermodynamic conditions of the reservoir from which they grow and therefore minerals record the evolution and variation of residual melt chemistry and intensive parameters within the magmatic system. A quantitative approach is required to determine if similar crystals actually shared a portion of their crystallisation history. These analyses are in many cases extremely time consuming and rather expensive. Therefore, it is not always possible to analyse a statically significant number of crystals, especially within their textural context in thin sections and that is the main reason to build automated methods. We are presenting a numerical cross-correlation method that compares the zonation pattern of minerals to identify if they share the totality or part of their growth history. We modified the method first developed by Wallace and Bergantz (2004) to compare profiles in minerals also from samples collected in different outcrops and that can be used for any dataset (i.e. geochemical proxies in stratigraphic sections). The main purpose of this method is to objectively compare chemical profiles in minerals (collected by electron microprobe, LA-ICP-MS or cathodoluminescence images) and quantify their degree of similarity. For this purpose, we use a well-known mathematical tool: the cross correlation which is a way of quantifying the difference between two given signals at a given position. Once our program was built, we performed tests using a set of synthetic profiles, profiles acquired along different transects of the same mineral and also on different minerals. Finally we applied our program to about 100 zircons from Kilgore Tuff, Heise Volcanic Field (USA) collected at different stratigraphic levels in two different outcrops. The correlation shows that

Volcanic eruptions on Io

Science.gov (United States)

Strom, R. G.; Schneider, N. M.; Terrile, R. J.; Hansen, C.; Cook, A. F.

1981-01-01

Nine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

Micro-PIGE determination of fluorine distribution in developing hamster tooth germs

International Nuclear Information System (INIS)

Lyaruu, D.M.; Lenglet, W.J.; Woeltgens, J.H.B.; Bronckers, A.L.

1989-01-01

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19 F(p,p', gamma) 19 F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly

SOLAR ERUPTION AND LOCAL MAGNETIC PARAMETERS

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeongwoo; Chae, Jongchul [Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of); Liu, Chang; Jing, Ju [Space Weather Research Laboratory, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

2016-11-10

It is now a common practice to use local magnetic parameters such as magnetic decay index for explaining solar eruptions from active regions, but there can be an alternative view that the global properties of the source region should be counted as a more important factor. We discuss this issue based on Solar Dynamics Observatory observations of the three successive eruptions within 1.5 hr from the NOAA active region 11444 and the magnetic parameters calculated using the nonlinear force-free field model. Two violent eruptions occurred in the regions with relatively high magnetic twist number (0.5–1.5) and high decay index (0.9–1.1) at the nominal height of the filament (12″) and otherwise a mild eruption occurred, which supports the local-parameter paradigm. Our main point is that the time sequence of the eruptions did not go with these parameters. It is argued that an additional factor, in the form of stabilizing force, should operate to determine the onset of the first eruption and temporal behaviors of subsequent eruptions. As supporting evidence, we report that the heating and fast plasma flow continuing for a timescale of an hour was the direct cause for the first eruption and that the unidirectional propagation of the disturbance determined the timing of subsequent eruptions. Both of these factors are associated with the overall magnetic structure rather than local magnetic properties of the active region.

Interrelation in the carpal bone index and orthopantomographic dental ages on the Korean children

Energy Technology Data Exchange (ETDEWEB)

Ahn, Hyung Kyu; You, Dong Soo; Park, Tae Won [College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

1973-11-15

The authors have taken the x-ray films of carpal bone and orthopantomographs in Korean children to research the degree of ossification of carpal bone, that of calcification of tooth in jaw bone, the eruption rate of tooth, and the completion rate of apical foramen, and have compared the bone age with tooth age. We have gained a series of interesting conclusions to dare to report. 1. The ossification of carpal bone and the growth of tooth had processed proportionally to each other. 2. Both the bone age and tooth age were earlier in the female than in the male. 3. The completion of tooth crown formation and that of tooth root formation had processed proportionally to each other, and the general tendency of process was earliest in the mandibular first molar and the latest in the second molar. 4. The eruption of tooth was earliest in the mandibular first molar. The other teeth had erupted in the following order : the central incisor, the lateral incisor, the first premolar, the second premolar, the canine, and the second molar.

Interrelation in the carpal bone index and orthopantomographic dental ages on the Korean children

International Nuclear Information System (INIS)

Ahn, Hyung Kyu; You, Dong Soo; Park, Tae Won

1973-01-01

The authors have taken the x-ray films of carpal bone and orthopantomographs in Korean children to research the degree of ossification of carpal bone, that of calcification of tooth in jaw bone, the eruption rate of tooth, and the completion rate of apical foramen, and have compared the bone age with tooth age. We have gained a series of interesting conclusions to dare to report. 1. The ossification of carpal bone and the growth of tooth had processed proportionally to each other. 2. Both the bone age and tooth age were earlier in the female than in the male. 3. The completion of tooth crown formation and that of tooth root formation had processed proportionally to each other, and the general tendency of process was earliest in the mandibular first molar and the latest in the second molar. 4. The eruption of tooth was earliest in the mandibular first molar. The other teeth had erupted in the following order : the central incisor, the lateral incisor, the first premolar, the second premolar, the canine, and the second molar.

Volcanic Eruptions and Climate: Outstanding Research Issues

Science.gov (United States)

Robock, Alan

2016-04-01

Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. Based on observations after major eruptions of the past and experiments with numerical models of the climate system, we understand much about their climatic impact, but there are also a number of unanswered questions. Volcanic eruptions produce global cooling, and are an important natural cause of interannual, interdecadal, and even centennial-scale climate change. One of the most interesting volcanic effects is the "winter warming" of Northern Hemisphere continents following major tropical eruptions. During the winter in the Northern Hemisphere following every large tropical eruption of the past century, surface air temperatures over North America, Europe, and East Asia were warmer than normal, while they were colder over Greenland and the Middle East. This pattern and the coincident atmospheric circulation correspond to the positive phase of the Arctic Oscillation. While this response is observed after recent major eruptions, most state-of-the-art climate models have trouble simulating winter warming. Why? High latitude eruptions in the Northern Hemisphere, while also producing global cooling, do not have the same impact on atmospheric dynamics. Both tropical and high latitude eruptions can weaken the Indian and African summer monsoon, and the effects can be seen in past records of flow in the Nile and Niger Rivers. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade have had a small effect on global temperature trends. Some important outstanding research questions include: How much seasonal, annual, and decadal predictability is possible following a large volcanic eruption? Do

Evolution of high tooth replacement rates in sauropod dinosaurs.

Science.gov (United States)

D'Emic, Michael D; Whitlock, John A; Smith, Kathlyn M; Fisher, Daniel C; Wilson, Jeffrey A

2013-01-01

Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently evolved the highest known tooth replacement rates among archosaurs.

Evolution of high tooth replacement rates in sauropod dinosaurs.

Directory of Open Access Journals (Sweden)

Michael D D'Emic

Full Text Available BACKGROUND: Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. METHODOLOGY/PRINCIPAL FINDINGS: We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days. Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. CONCLUSIONS/SIGNIFICANCE: Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size, and derived titanosaurs and

CME Eruption Onset Observations from EIT and SXT

Science.gov (United States)

Sterling, A. C.

2004-01-01

Why CMEs erupt is a major outstanding puzzle of solar physics. Signatures observable at the earliest stages of eruption onset may hold precious clues about the onset mechanism. We present observations in EUV from SOHO/EIT and in soft X-rays from Yohkoh/SXT of the re-eruption and eruption phases of CME expulsion, along with the eruption's magnetic setting found from SOHO/MDI magnetograms. Most of our events involve clearly-observable filament eruptions and multiple neutral lines, and we use the magnetic settings and motions of the filaments to help infer the geometry and behavior of the associated erupting magnetic fields. Pre-eruption and early-eruption signatures include a relatively slow filament rise prior to eruption, and intensity "dimmings" and brightenings, both in the immediate neighborhood of the "core" (location of greatest magnetic shear) of the erupting fields and at locations remote from the core. These signatures and their relative timings place observational constraints on eruption mechanisms; our recent work has focused on implications for the so-called "tether cutting" and "breakout" models, but the same observational constraints are applicable to any model.

Ozone depletion following future volcanic eruptions

Science.gov (United States)

Eric Klobas, J.; Wilmouth, David M.; Weisenstein, Debra K.; Anderson, James G.; Salawitch, Ross J.

2017-07-01

While explosive volcanic eruptions cause ozone loss in the current atmosphere due to an enhancement in the availability of reactive chlorine following the stratospheric injection of sulfur, future eruptions are expected to increase total column ozone as halogen loading approaches preindustrial levels. The timing of this shift in the impact of major volcanic eruptions on the thickness of the ozone layer is poorly known. Modeling four possible climate futures, we show that scenarios with the smallest increase in greenhouse gas concentrations lead to the greatest risk to ozone from heterogeneous chemical processing following future eruptions. We also show that the presence in the stratosphere of bromine from natural, very short-lived biogenic compounds is critically important for determining whether future eruptions will lead to ozone depletion. If volcanic eruptions inject hydrogen halides into the stratosphere, an effect not considered in current ozone assessments, potentially profound reductions in column ozone would result.

In vitro demineralization of tooth enamel subjected to two whitening regimens.

Science.gov (United States)

Ogura, Kayoko; Tanaka, Reina; Shibata, Yo; Miyazaki, Takashi; Hisamitsu, Hisashi

2013-07-01

The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation. The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer. Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization. The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth. OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.

Management of immature teeth with apical infections using mineral trioxide aggregate

Directory of Open Access Journals (Sweden)

Sivakumar Nuvvula

2010-01-01

Full Text Available Traumatic injuries to the young permanent teeth lead to devitalization of the pulp with concomitant arrest in further development of the immature root of the involved tooth. Hermetic seal of the root canal system during obturation is not possible in such cases, due to the lack of an apical constriction. The traditional management technique in such cases has been apexification involving induction of a calcific barrier at the apex using calcium hydroxide, which in turn facilitates obturation of the root canal. However this becomes complicated when there is persistent infection leading to periapical changes. This case report describes the use of mineral trioxide aggregate (MTA for management of a periapically compromised immature tooth.

Endodontic Treatment of an Anomalous Anterior Tooth with the Aid of a 3-dimensional Printed Physical Tooth Model.

Science.gov (United States)

Byun, Chanhee; Kim, Changhwan; Cho, Seungryong; Baek, Seung Hoon; Kim, Gyutae; Kim, Sahng G; Kim, Sun-Young

2015-06-01

Endodontic treatment of tooth formation anomalies is a challenge to clinicians and as such requires a complete understanding of the aberrant root canal anatomy followed by careful root canal disinfection and obturation. Here, we report the use of a 3-dimensional (3D) printed physical tooth model including internal root canal structures for the endodontic treatment of a challenging tooth anomaly. A 12-year-old boy was referred for endodontic treatment of tooth #8. The tooth showed class II mobility with swelling and a sinus tract in the buccal mucosa and periapical radiolucency. The tooth presented a very narrow structure between the crown and root by distal concavity and a severely dilacerated root. Moreover, a perforation site with bleeding and another ditching site were identified around the cervical area in the access cavity. A translucent physical tooth model carrying the information on internal root canal structures was built through a 3-step process: data acquisition by cone-beam computed tomographic scanning, virtual modeling by image processing, and manufacturing by 3D printing. A custom-made guide jig was then fabricated to achieve a safe and precise working path to the root canal. Endodontic procedures including access cavity preparation were performed using the physical tooth model and the guide jig. At the 7-month follow-up, the endodontically treated tooth showed complete periapical healing with no clinical signs and symptoms. This case report describes a novel method of endodontic treatment of an anomalous maxillary central incisor with the aid of a physical tooth model and a custom-made guide jig via 3D printing technique. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Establishing the chronology of explosive super-eruptions in the record of the Yellowstone hotspot track (Invited)

Science.gov (United States)

Reichow, M. K.; Branney, M. J.; Knott, T.; Storey, M.; Finn, D. R.; Coe, R. S.; McCurry, M. O.; Bonnichsen, B.

2013-12-01

Although caldera-forming super-eruptions (≥450 km3) are amongst the most catastrophic events to affect the Earth's surface, we do not know how often they occur globally, and how large the individual eruptions are. This is because, with a few exceptions, the vast volcanic stratigraphies at many large igneous provinces have not yet been resolved in sufficient detail to isolate and quantify the individual events. Much progress is needed on this if we are to verify the past and potential environmental and climatic impact of these super-eruptions. We are reconstructing the history of catastrophic eruptions in the youngest and best-preserved large intra continental volcanic province worldwide, by resolving the vast Miocene rhyolitic volcanic stratigraphy of the central Snake River Plain, Idaho. Large explosive eruptions, several previously un-documented, generated an unusually hot (searing-hot rhyolitic glass 5-100 m thick. The density currents also generated thermal atmospheric plumes (phoenix clouds) that dispersed 100's to 1000's of km3 rhyolitic ash 1000's of km across continental USA and beyond. High-precision chronology and quantification of the erupted volumes and the frequency of eruptions is needed to assess the likely significant wider impact of these events on climate and ecosystems. To determine the size of the individual events, we have been correlating each soil-bounded eruption-unit regionally. This is hindered by their abundance, and closely similar appearance within monotonous successions exposed in distant (50-200 km) mountain ranges. To tackle this we are employing a combination of tools to isolate and correlate individual layers: field logging coupled with characterization of the whole-rock, glass, and mineral chemistries, together with high-precision 40Ar/39Ar dating, U-Pb zircon dating, with detailed paleomagnetic characterisation of polarities and secular variations. This multidisciplinary approach is yielding robust ';fingerprints'; to

Stratigraphy, distribution, and evidence for mafic triggering of the ca. 8.5 ka Driftwood Pumice eruption, Makushin Volcano, Alaska, U.S.A

Science.gov (United States)

Lerner, Allan H.; Crowley, Peter D.; Nicolaysen, Kirsten P.; Hazlett, Richard W.

2018-05-01

Makushin Volcano on Unalaska Island, Alaska, threatens the Aleutian's largest population centers (Unalaska and Dutch Harbor), yet its eruption mechanisms are poorly known. This study presents a detailed stratigraphic and geochemical investigation of Makushin's most recent highly explosive event: the ca. 8.5 ka Driftwood Pumice eruption. The Driftwood Pumice has measured thicknesses of over 2.5 m, and isopach reconstructions estimate a total deposit volume of 0.3 to 1.6 km3, indicating a VEI 4-5 eruption. Proximal deposits consist of normally-graded, tan, dacitic to andesitic pumice, capped by a thinner dark layer of lower-silica andesitic scoria mixed with abundant lithic fragments. This stratigraphy is interpreted as an initial vent-clearing eruption that strengthened into a climactic ejection of pumice and ash and concluded with vent destabilization and the eruption of somewhat more mafic, gas-poor magma. Within the pumice, geochemical trends, disequilibrium mineral populations, and mineral zonation patterns show evidence of magma mixing between a bulk silicic magma and a mafic melt. Euhedral high-Ca plagioclase (An68-91) and high-Mg olivine (Fo69-77) phenocrysts are in disequilibrium with trachydacitic glass (65-68 wt% SiO2) and more abundant sodic plagioclase (An34-55), indicating the former originally crystallized in a more mafic melt. Tephra whole rock compositions become more mafic upwards through the deposit, ranging from a basal low-silica dacite to an andesite (total range: 60.8-63.3 wt% SiO2). Collectively, these compositional variations suggest magma mixing in the Driftwood Pumice (DWP) magma reservoir, with a systematic increase in the amount of a mafic component (up to 25%) upward through the deposit. Olivine-liquid and liquid-only thermometry indicate the mafic magma intruded at temperatures 140-200 °C hotter than the silicic magma. Diffusion rates calculated for 5-7 μm thick, lower-Mg rims on the olivine phenocrysts (Fo60 rim vs Fo76 bulk) suggest

Position and Eruption of Permanent Maxillary Canines in Cases of Maxillary Lateral Incisor Agenesis in Mixed Dentition.

Science.gov (United States)

Lamas, Cátia; Lavall, Asela; Pinho, Teresa

2018-01-01

Assess whether the permanent maxillary canine (MC) has a natural tendency to erupt mesially in children with maxillary lateral incisors agenesis (MLIA), compared to children without agenesis. This retrospective, observational, cross-sectional study consisted of children between 5 and 12 years old divided into three groups: the first group with unilateral MLIA, in which an intraindividual analysis was performed, the second group presented bilateral MLIA, and the third group with patients without agenesis. These last two groups were matched for comparison interindividual, being pared by sex and maturation of the MC. The canine position in the horizontal sector showed a clear mesial positioning of the MC on the agenesis side in individuals with unilateral MLIA (group 1) when compared with the counter lateral side; and in individuals with bilateral MLIA (Group 2) compared with control Individuals without agenesis (group 3). Even with the maintenance of this deciduous tooth in the dental arch, the MC keeps its tendency to mesial eruption. There is a greater tendency for mesial angulation of the maxillary canine in patients with MLIA, regardless of the presence or absence of deciduous lateral incisor.

Loss of epithelial FAM20A in mice causes amelogenesis imperfecta, tooth eruption delay and gingival overgrowth.

Science.gov (United States)

Li, Li-Li; Liu, Pei-Hong; Xie, Xiao-Hua; Ma, Su; Liu, Chao; Chen, Li; Qin, Chun-Lin

2016-06-30

FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM20A in dental tissues and to assess the pathological changes when this molecule is specifically nullified in individual tissues. Recently, we generated mice with a Fam20A-floxed allele containing the beta-galactosidase reporter gene. We analysed FAM20A expression in dental tissues using X-Gal staining, immunohistochemistry and in situ hybridization, which showed that the ameloblasts in the mouse mandibular first molar began to express FAM20A at 1 day after birth, and the reduced enamel epithelium in erupting molars expressed a significant level of FAM20A. By breeding K14-Cre mice with Fam20A(flox/flox) mice, we created K14-Cre;Fam20A(flox/flox) (conditional knock out, cKO) mice, in which Fam20A was inactivated in the epithelium. We analysed the dental tissues of cKO mice using X-ray radiography, histology and immunohistochemistry. The molar enamel matrix in cKO mice was much thinner than normal and was often separated from the dentinoenamel junction. The Fam20A-deficient ameloblasts were non-polarized and disorganized and were detached from the enamel matrix. The enamel abnormality in cKO mice was consistent with the diagnosis of amelogenesis imperfecta. The levels of enamelin and matrix metalloproteinase 20 were lower in the ameloblasts and enamel of cKO mice than the normal mice. The cKO mice had remarkable delays in the eruption of molars and hyperplasia of the gingival epithelium. The findings emphasize the essential roles of FAM20A in the development of dental and oral tissues.

Primary culprit for tooth loss!!

OpenAIRE

Nuvvula, Sailavanya; Chava, Vijay Kumar; Nuvvula, Sivakumar

2016-01-01

Aim: In order to facilitate planning for dental health services and to progress strategies to continue the reduction in tooth loss, it is important to identify the factors that result in such loss. therefore the aim of the study is to investigate the major cause for tooth extraction. Objective: to examine whether the major reason for tooth extraction is dental caries or periodontal disease. Materials and Methods: The study is carried out among the dental practitioners in our district. A quest...

Flux Cancellation Leading to CME Filament Eruptions

Science.gov (United States)

Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

Pre-eruptive conditions of dacitic magma erupted during the 21.7 ka Plinian event at Nevado de Toluca volcano, Central Mexico

Science.gov (United States)

Arce, J. L.; Gardner, J. E.; Macías, J. L.

2013-01-01

The Nevado de Toluca volcano in Central Mexico has been active over the last ca. 42 ka, during which tens of km3 of pyroclastic material were erupted and two important Plinian-type eruptions occurred at ca. 21.7 ka (Lower Toluca Pumice: LTP) and ca. 10.5 ka (Upper Toluca Pumice: UTP). Samples from both the LTP and UTP contain plagioclase, amphibole, iron-titanium oxides, and minor anhedral biotite, set in a vesicular, rhyolitic, glassy matrix. In addition, UTP dacites contain orthopyroxene. Analysis of melt inclusions in plagioclase phenocrysts yields H2O contents of 2-3.5 wt.% for LTP and 1.3-3.6 wt.% for UTP samples. Ilmenite-ulvospinel geothermometry yields an average temperature of ~ 868 °C for the LTP magma (hotter than the UTP magma, ~ 842 °C; Arce et al., 2006), whereas amphibole-plagioclase geothermometry yields a temperature of 825-859 °C for the LTP magma. Water-saturated experiments using LTP dacite suggest that: (i) amphibole is stable above 100 MPa and below 900 °C; (ii) plagioclase crystallizes below 250-100 MPa at temperatures of 850-900 °C; and (iii) pyroxene is stable only below pressures of 200-100 MPa and temperatures of 825-900 °C. Comparison of natural and experimental data suggests that the LTP dacitic magma was stored at 150-200 MPa (5.8-7.7 km below the volcano summit). No differences in pressure found between 21.7 ka and 10.5 ka suggest that these two magmas were stored at similar depths. Orthopyroxene produced in lower temperature LTP experiments is compositionally different to those found in UTP natural samples, suggesting that they originated in two different magma batches. Whole-rock chemistry, petrographic features, and mineral compositions suggest that magma mixing was responsible for the generation of the dacitic Plinian LTP eruption.

Clinical, radiographic, and histological observation of a human immature permanent tooth with chronic apical abscess after revitalization treatment.

Science.gov (United States)

Shimizu, Emi; Ricucci, Domenico; Albert, Jeffrey; Alobaid, Adel S; Gibbs, Jennifer L; Huang, George T-J; Lin, Louis M

2013-08-01

Revitalization procedures have been widely used for the treatment of immature permanent teeth with apical periodontitis. The treatment procedures appear to be capable of encouraging continued root development and thickening of the canal walls. The nature of tissues formed in the canal space and at the root apex after revitalization has been shown histologically in several animal studies; similar studies in humans were recently reported. A 9-year-old boy had a traumatic injury to his upper anterior teeth. Tooth #9 suffered a complicated crown fracture with a pulp exposure, which was restored with a composite resin. The tooth developed a chronic apical abscess. Revitalization procedures were performed on tooth #9 because it was an immature permanent tooth with an open apex and thin canal walls. Twenty-six months after revitalization, the tooth had a horizontal crown fracture at the cervical level and could not be restored. The tooth was extracted and processed for routine histological and immunohistochemical examination to identify the nature of tissues formed in the canal space. Clinically and radiographically, the revitalization of the present case was successful because of the absence of signs and symptoms and the resolution of periapical lesion as well as thickening of the canal walls and continued root development. The tissue formed in the canal was well-mineralized cementum- or bone-like tissue identified by routine histology and immunohistochemistry. No pulp-like tissue characterized by the presence of polarized odontoblast-like cells aligning dentin-like hard tissue was observed. The tissues formed in the canal of revitalized human tooth are similar to cementum- or bone-like tissue and fibrous connective tissue. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Mechanical Forces Exacerbate Periodontal Defects in Bsp-null Mice

Science.gov (United States)

Soenjaya, Y.; Foster, B.L.; Nociti, F.H.; Ao, M.; Holdsworth, D.W.; Hunter, G.K.; Somerman, M.J.

2015-01-01

Bone sialoprotein (BSP) is an acidic phosphoprotein with collagen-binding, cell attachment, and hydroxyapatite-nucleating properties. BSP expression in mineralized tissues is upregulated at onset of mineralization. Bsp-null (Bsp-/-) mice exhibit reductions in bone mineral density, bone turnover, osteoclast activation, and impaired bone healing. Furthermore, Bsp-/- mice have marked periodontal tissue breakdown, with a lack of acellular cementum leading to periodontal ligament detachment, extensive alveolar bone and tooth root resorption, and incisor malocclusion. We hypothesized that altered mechanical stress from mastication contributes to periodontal destruction observed in Bsp-/- mice. This hypothesis was tested by comparing Bsp-/- and wild-type mice fed with standard hard pellet diet or soft powder diet. Dentoalveolar tissues were analyzed using histology and micro–computed tomography. By 8 wk of age, Bsp-/- mice exhibited molar and incisor malocclusion regardless of diet. Bsp-/- mice with hard pellet diet exhibited high incidence (30%) of severe incisor malocclusion, 10% lower body weight, 3% reduced femur length, and 30% elevated serum alkaline phosphatase activity compared to wild type. Soft powder diet reduced severe incisor malocclusion incidence to 3% in Bsp-/- mice, supporting the hypothesis that occlusal loading contributed to the malocclusion phenotype. Furthermore, Bsp-/- mice in the soft powder diet group featured normal body weight, long bone length, and serum alkaline phosphatase activity, suggesting that tooth dysfunction and malnutrition contribute to growth and skeletal defects reported in Bsp-/- mice. Bsp-/- incisors also erupt at a slower rate, which likely leads to the observed thickened dentin and enhanced mineralization of dentin and enamel toward the apical end. We propose that the decrease in eruption rate is due to a lack of acellular cementum and associated defective periodontal attachment. These data demonstrate the importance of BSP

Atypical Odontalgia (Phantom Tooth Pain)

Science.gov (United States)

... atypical facial pain, phantom tooth pain, or neuropathic orofacial pain, is characterized by chronic pain in a tooth ... such as a specialist in oral medicine or orofacial pain. The information contained in this monograph is for ...

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

Energy Technology Data Exchange (ETDEWEB)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong [Chiang Mai University, Chiang Mai (Thailand)

2013-12-15

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

International Nuclear Information System (INIS)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-01-01

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Effect of Er,Cr:YSGG laser irradiation on bovine enamel surface during in-office tooth bleaching ex vivo.

Science.gov (United States)

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia; Koumpia, Effimia

2017-07-01

The aim of this in vitro study was to evaluate the effect of using Er,Cr:YSGG laser during in-office tooth bleaching on bovine enamel surface to evaluate the safety of this therapy on tooth tissues. Thirty-six enamel specimens were prepared from bovine incisors and divided into three groups: Group 1 specimens (control) received no bleaching treatment; Group 2 received a conventional in-office bleaching treatment (40 % H 2 O 2 ); Group 3 received laser-assisted bleaching procedure (40 % H 2 O 2 ) utilizing an Er,Cr:YSGG laser. The specimens were stored for 10 days after the bleaching treatment in artificial saliva. Vickers hardness was determined using a microhardness tester, and measurements for surface roughness were done using a VSI microscope. Three specimens for each experimental group were examined under SEM and mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post hoc, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The Vickers hardness of the enamel was reduced after in-office bleaching procedures (p  0.05), and no changes in mineral composition of the enamel were detected after in-office bleaching procedures (p > 0.05). The laser-assisted bleaching treatment with Er,Cr:YSGG laser did not influence the enamel surface compared to the conventional bleaching technique. The safety of the use of Er,Cr:YSGG laser during in-office tooth bleaching regarding the surface properties of the enamel was confirmed under in vitro conditions.

Surgical exposure of an impacted maxillary canine and increasing a band of keratinized gingiva

Directory of Open Access Journals (Sweden)

Vijayalakshmi R

2009-01-01

Full Text Available An adequate amount of keratinized gingival tissue that is under proper plaque control, is a fundamental requirement for periodontal health. When the teeth erupt uneventfully in the center of the alveolar ridge, an adequate amount of keratinized tissue will surround the erupted permanent tooth. Labially or buccally erupting teeth show reduced dimensions of the gingiva as abnormal eruption of permanent teeth restricts or eliminates the keratinized tissue between the erupting cusp and the deciduous tooth. A lack of attached gingiva poses a potential risk for gingival recession in labially or buccally erupted teeth due to the possibility of accumulation of plaque and/or traumatic tooth-brushing during subsequent orthodontic treatment. A good understanding between the orthodontist and periodontist along with proper management of periodontal tissues, can prevent these problems. Various surgical techniques can be employed to uncover impacted teeth. This paper discusses the validity of utilizing periodontal surgery to increase a band of keratinized tissue in a case of an impacted canine erupting from the alveolar mucosa.

Tooth breakage in patients injected with 224Ra

International Nuclear Information System (INIS)

Sonnabend, E.; Spiess, H.; Mays, C.W.

1986-01-01

Tooth breakage has been common among the 224 Ra patients, especially those injected as teenagers. The fracture of 1 or more teeth was reported by 26% (8/31) of boys and 23% (7/30) of girls injected with 224 Ra at 16-20 years of age. Combining results from all age groups, the incidence of tooth fractures increased significantly with dose (P=0.01). Unlike the normal loss of permanent teeth by periodontal disease, in which the entire tooth is lost, the tooth loss following 224 Ra injection was primarily from tooth resorption near the gum line causing the tooth crowns to break off easily. Eventually the tooth roots may either become incorporated into the jawbone or are resorbed and replaced with bone. These tooth fractures resembled those observed in the U.S. radium dial painters and in dogs injected with bone-seeking α-emitters. (orig.)

When does eruption run-up begin? Multidisciplinary insight from the 1999 eruption of Shishaldin volcano

Science.gov (United States)

Rasmussen, Daniel J.; Plank, Terry A.; Roman, Diana C.; Power, John A.; Bodnar, Robert J.; Hauri, Erik H.

2018-03-01

During the run-up to eruption, volcanoes often show geophysically detectable signs of unrest. However, there are long-standing challenges in interpreting the signals and evaluating the likelihood of eruption, especially during the early stages of volcanic unrest. Considerable insight can be gained from combined geochemical and geophysical studies. Here we take such an approach to better understand the beginning of eruption run-up, viewed through the lens of the 1999 sub-Plinian basaltic eruption of Shishaldin volcano, Alaska. The eruption is of interest due to its lack of observed deformation and its apparent long run-up time (9 months), following a deep long-period earthquake swarm. We evaluate the nature and timing of recharge by examining the composition of 138 olivine macrocrysts and 53 olivine-hosted melt inclusions and through shear-wave splitting analysis of regional earthquakes. Magma mixing is recorded in three crystal populations: a dominant population of evolved olivines (Fo60-69) that are mostly reversely zoned, an intermediate population (Fo69-76) with mixed zonation, and a small population of normally zoned more primitive olivines (Fo76-80). Mixing-to-eruption timescales are obtained through modeling of Fe-Mg interdiffusion in 78 olivines. The large number of resultant timescales provides a thorough record of mixing, demonstrating at least three mixing events: a minor event ∼11 months prior to eruption, overlapping within uncertainty with the onset of deep long-period seismicity; a major event ∼50 days before eruption, coincident with a large (M5.2) shallow earthquake; and a final event about a week prior to eruption. Shear-wave splitting analysis shows a change in the orientation of the local stress field about a month after the deep long-period swarm and around the time of the M5.2 event. Earthquake depths and vapor saturation pressures of Raman-reconstructed melt inclusions indicate that the recharge magma originated from depths of at least 20

Autotransplantation donor tooth site harvesting using piezosurgery

OpenAIRE

Ylikontiola, Leena P.; S?ndor, George K.

2016-01-01

Abstract Background: The harvesting of a tooth as a candidate for tooth autotransplantation requires that the delicate dental tissues around the tooth be minimally traumatized. This is especially so for the periradicular tissues of the tooth root and the follicular tissues surrounding the crown. The aim of this report is to describe the use of piezosurgery as an attempt at morbidity reduction in the harvesting of teeth for autotransplantation. Methods: A piezosurgical handpiece and its ...

Reduced cooling following future volcanic eruptions

Science.gov (United States)

Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.

2017-11-01

Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

Proteomic analysis of human tooth pulp: proteomics of human tooth.

Science.gov (United States)

Eckhardt, Adam; Jágr, Michal; Pataridis, Statis; Mikšík, Ivan

2014-12-01

The unique pulp-dentin complex demonstrates strong regenerative potential, which enables it to respond to disease and traumatic injury. Identifying the proteins of the pulp-dentin complex is crucial to understanding the mechanisms of regeneration, tissue calcification, defense processes, and the reparation of dentin by dental pulp. The lack of knowledge of these proteins limits the development of more efficient therapies. The proteomic profile of human tooth pulp was investigated and compared with the proteome of human dentin and blood. The samples of tooth pulp were obtained from 5 sound permanent human third molars of 5 adults (n = 5). The extracted proteins were separated by 2-dimensional gel electrophoresis, analyzed by nano-liquid chromatography tandem mass spectrometry, and identified by correlating mass spectra to the proteomic databases. A total of 342 proteins were identified with high confidence, and 2 proteins were detected for the first time in an actual human sample. The identified tooth pulp proteins have a variety of functions: structural, catalytic, transporter, protease activity, immune response, and many others. In a comparison with dentin and blood plasma, 140 (pulp/dentin) shared proteins were identified, 37 of which were not observed in plasma. It can be suggested that they might participate in the unique pulp-dentin complex. This proteomic investigation of human tooth pulp, together with the previously published study of human dentin, is one of the most comprehensive proteome lists of human teeth to date. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Decompression Induced Crystallization of Basaltic Andesite Magma: Constraints on the Eruption of Arenal Volcano, Costa Rica.

Science.gov (United States)

Szramek, L. A.; Gardner, J. E.; Larsen, J. F.

2004-12-01

Arenal Volcano is a small stratovolcano located 90 km NW of San Jose, Costa Rica. In 1968 current activity began with a Plinian phase, and has continued to erupt lava flows and pyroclastic flows intermittently since. Samples from the Plinian, pyroclastic flow, strombolian, and effusive phases have been studied texturally. Little variation in crystallinity occurs amongst the different phases. Number density of crystals, both 2D and 3D are 50-70 mm-2 and 30,000-50,000 mm-3 in the Plinian sample, compared to the lesser values in other eruptive types. Characteristic crystal size also increases as explosivity decreases. Two samples, both lava flows collected while warm, overlap with the Plinian sample. This suggests that the variations seen may be a result of cooling history. Plagioclase differs between the Plinian sample, in which they are only tabular in shape, and the other eruptive types, which contain both tabular and equant crystals. To link decompression paths of the Arenal magma to possible pre-eruptive conditions, we have carried out hydrothermal experiments. The experiments were preformed in TZM pressure vessels buffered at a fugacity of Ni-NiO and water saturation. Phase equilibria results in conjunction with mineral compositions and temperature estimates by previous workers from active lava flows and two-pyroxene geothermometry, constrain the likely pre-eruptive conditions for the Arenal magma to 950-1040° C with a water pressure of 50-80 MPa. Samples that started from conditions that bracket our estimated pre-eruptive conditions were decompressed in steps of 5-30 MPa and held for various times at each step until 20 MPa was reached, approximating average decompression rates of 0.25, 0.025, 0.0013 MPa/s. Comparison of textures found in the natural samples to the experimentally produced textures suggest that the Plinian eruption likely was fed by magma ascending at 0.05-1 m/s, whereas the less explosive phases were fed by magma ascending at 0.05 m/s or less.

Prediction of width of un-erupted incisors, canines and premolars in a Ugandan population: A cross sectional study

Directory of Open Access Journals (Sweden)

Buwembo William

2012-07-01

Full Text Available Abstract Background Accurate prediction of the space forms an important part of an orthodontic assessment in the mixed dentition. However the most commonly used methods of space analysis are based on data developed on Caucasian populations. In order to provide more accurate local data we set out to develop a formula for predicting the widths of un-erupted canines and premolars for a Ugandan population and to compare the predicted widths of the teeth from this formula with those obtained from Moyers’ tables, and Tanaka and Johnston’s equations. Methods Dental casts were prepared using mandibular and maxillary arch impressions of 220 children (85 boys/135 girls aged 12–17 years recruited from schools in Kampala, Uganda. The mesio-distal width of the mandibular incisors, mandibular and maxillary canines and premolars were measured with a pair of digital calipers. Based on regression analysis, predictive equations were derived and the findings were compared with those presented in Moyers’ probability tables, and Tanaka and Johnston’s equations. Results There were no statistically significant differences between the tooth widths predicted by our equations and those from Moyers’ probability tables at the 65th and 75th percentile probabilities for the girls and at 75th level in boys in the mandibular arch. While in the maxillary arch no statistically significant differences at the 75th and 95th levels were noted in girls. There were statistically significant differences between predicted tooth sizes using equations from the present study and those predicted from the Tanaka and Johnston regression equations. Conclusions In this Ugandan population, Moyers’ probability tables could be used to predict tooth widths at specific percentile probabilities, but generally, Tanaka and Johnston technique tends to overestimate the tooth widths.

Correlation and stratigraphic eruption age of the pyroclastic flow deposits and wide spread volcanic ashes intercalated in the Pliocene-Pleistocene strata, central Japan

International Nuclear Information System (INIS)

Nagahashi, Yoshitaka; Satoguchi, Yasufumi; Yoshikawa, Shusaku

2000-01-01

Three pyroclastic flow deposits in the Takayama and Omine area, central Honshu, are correlated to the distal widespread volcanic ashes intercalated in the Plio-Pleistocene boundary strata in central Japan. The correlation is based on these stratigraphic relationships, facies, magnetostratigraphy, petrographic properties such as mineral assemblage, refractive index and chemical composition of the volcanic glasses and orthopyroxene. As the result of these correlation, the eruption age of the proximal pyroclastic flow deposits have become clear. And precise correlation between proximal eruption units and distal depositional units is now possible. Ho-Kd 39 Tephra erupted at about 1.76 Ma, forming a co-ignimbrite ash, which deposited in the Kanto sedimentary basin. Eb-Fukuda Tephra erupted at about 1.75 Ma, and distal volcaniclastic deposit sedimented in the Kinki, Niigata and Kanto sedimentary basins. The eruptional and depositional phase are divided into the stage 1, stage 2 (early), stage 2 (late) and stage 3. Stage 1 is phreato-plinian type eruption phase, forming distal ash fall deposit. Stage 2 (early) is plinian pumice fall, intra-plinian pyroclastic flow and plinian pumice fall eruption phase, forming distal ash fall. Stage 2 (late) is final eruptional phase of the biggest pyroclastic flow of the Eb-Fukuda Tephra, forming a co-ignimbrite ash fall. Stage 3 is resedimented stage after the end of the explosive eruption. It is notable that resedimented volcaniclastic deposit reached Osaka sedimentary basin 300 km away from the eruption center. Om-SK110 Tephra erupted at about 1.65 Ma, divided into the stage 1, stage 2 and stage 3. Stage 1 is eruption phase of the plinian pumice fall and first pyroclastic flow. Stage 2 is pauses in eruption activity. Stage 3 is second pyroclastic flow phase, it is inferred that the pyroclastic flow of the stage 3 directly entered the Niigata sedimentary basin and simultaneously formed a co-ignimbrite ash. (author)

Six upper incisors: what's next?

Science.gov (United States)

Berneburg, Mirjam; Meller, Christian

2016-01-01

This case report describes our therapeutic approach taken in a girl with eruption disturbance of the upper anterior teeth. Two supernumerary teeth were involved, which required a combination of orthodontic and surgical treatment. The initial situation in the upper anterior segment was characterized by two supernumerary mesial incisors, ectopic eruption of the distally located lateral incisors, and crowded tooth buds in the canine areas. Key decisions had to be made as to whether any teeth needed to be extracted and, if so, regarding the timing and sites of extraction. Removing teeth too early would have preempted a complete assessment of tooth quality, whereas late extraction would have carried a risk of eruption disturbance. Once the distal lateral incisors had erupted, the supernumerary mesial incisors were extracted and the central incisors (initially located in between) mesialized with a bracket appliance. Following space closure and mesialization of the lateral incisors, a functional appliance was used. Tooth 13 was erupting, while tooth 23 was displaced and subsequently aligned as part of the final bracket treatment. To successfully treat eruption disturbances, a careful diagnostic workup is essential, including informative radiographs, personalized treatment planning, and correct decision-making as to whether teeth need to be extracted and regarding the timing and sites of extraction. Finally, the eruption of the canines should be monitored.

The 2014 eruptions of Pavlof Volcano, Alaska

Science.gov (United States)

Waythomas, Christopher F.; Haney, Matthew M.; Wallace, Kristi; Cameron, Cheryl E.; Schneider, David J.

2017-12-22

Pavlof Volcano is one of the most frequently active volcanoes in the Aleutian Island arc, having erupted more than 40 times since observations were first recorded in the early 1800s . The volcano is located on the Alaska Peninsula (lat 55.4173° N, long 161.8937° W), near Izembek National Wildlife Refuge. The towns and villages closest to the volcano are Cold Bay, Nelson Lagoon, Sand Point, and King Cove, which are all within 90 kilometers (km) of the volcano (fig. 1). Pavlof is a symmetrically shaped stratocone that is 2,518 meters (m) high, and has about 2,300 m of relief. The volcano supports a cover of glacial ice and perennial snow roughly 2 to 4 cubic kilometers (km3) in volume, which is mantled by variable amounts of tephra fall, rockfall debris, and pyroclastic-flow deposits produced during historical eruptions. Typical Pavlof eruptions are characterized by moderate amounts of ash emission, lava fountaining, spatter-fed lava flows, explosions, and the accumulation of unstable mounds of spatter on the upper flanks of the volcano. The accumulation and subsequent collapse of spatter piles on the upper flanks of the volcano creates hot granular avalanches, which erode and melt snow and ice, and thereby generate watery debris-flow and hyperconcentrated-flow lahars. Seismic instruments were first installed on Pavlof Volcano in the early 1970s, and since then eruptive episodes have been better characterized and specific processes have been documented with greater certainty. The application of remote sensing techniques, including the use of infrasound data, has also aided the study of more recent eruptions. Although Pavlof Volcano is located in a remote part of Alaska, it is visible from Cold Bay, Sand Point, and Nelson Lagoon, making distal observations of eruptive activity possible, weather permitting. A busy air-travel corridor that is utilized by a numerous transcontinental and regional air carriers passes near Pavlof Volcano. The frequency of air travel

Complicated lichenoid drug eruption.

Science.gov (United States)

Armour, Katherine; Lowe, Patricia

2005-02-01

We report a case of severe lichenoid drug eruption with multiple possible causative agents. A hepatitis C-positive male presented with a short history of painful erosions of the vermilion, lichenoid lesions on the buccal mucosa and glans penis, and erosions and lichenification of the scrotum. In addition, he had a pruritic polymorphic eruption over the scalp, trunk and limbs, comprising psoriasiform and eczematous lesions. He had received combination therapy of pegylated interferon-alpha-2a and ribavirin, along with granulocyte colony-stimulating factor for interferon-induced leucopenia, and propranolol for portal hypertension. The former three agents were ceased 3 weeks prior to presentation, but he remained on propranolol at the initial dermatology consultation. The polymorphous clinical picture was consistent with lichenoid drug eruption, which was confirmed on histology. The papulosquamous eruption responded quickly to 2 weeks of oral prednisone 25 mg daily, which was tapered to 1 mg over 3 months and then ceased. The mucosal lesions were slow to improve and required the addition of tacrolimus 0.03% solution t.d.s. for complete resolution.

Test Tube Tooth: The Next Big Thing.

Science.gov (United States)

Yadav, Preeti; Tahir, Mohammed; Yadav, Harsh; Sureka, Rakshit; Garg, Aarti

2016-06-01

Unlike some vertebrates and fishes, humans do not have the capacity for tooth regeneration after the loss of permanent teeth. Although artificial replacement with removable dentures, fixed prosthesis and implants is possible through advances in the field of prosthetic dentistry, it would be ideal to recreate a third set of natural teeth to replace lost dentition. For many years now, researchers in the field of tissue engineering have been trying to bioengineer dental tissues as well as whole teeth. In order to attain a whole tooth through dental engineering, that has the same or nearly same biological, mechanical and physical properties of a natural tooth, it's necessary to deal with all the cells and tissues which are concerned with the formation, maintenance and repair of the tooth. In this article we review the steps involved in odontogenesis or organogenesis of a tooth and progress in the bioengineering of a whole tooth.

Erupted Compound Odontomas: A Case Report

Directory of Open Access Journals (Sweden)

Avinash Tejasvi M.L.

2011-03-01

Full Text Available The tumors in which odontogenic differentiation is fully expressed are the odontomas. Odontomas are considered as hamartomas rather than a true neoplasm. These tumors are composed of enamel, dentine, cementum and pulp tissue. It is most commonly associated with the eruption of the teeth. They are usually discovered on routine radiographic examination. In exceptional cases, the odontoma erupts in to the mouth. Nine cases of erupted compound odontomas are reported in the English literature, and the present paper reports another case of an erupted compound odontoma in a 22-year-old female patient.

A cascade of magmatic events during the assembly and eruption of a super-sized magma body

Science.gov (United States)

Allan, Aidan. S. R.; Barker, Simon J.; Millet, Marc-Alban; Morgan, Daniel J.; Rooyakkers, Shane M.; Schipper, C. Ian; Wilson, Colin J. N.

2017-07-01

We use comprehensive geochemical and petrological records from whole-rock samples, crystals, matrix glasses and melt inclusions to derive an integrated picture of the generation, accumulation and evacuation of 530 km3 of crystal-poor rhyolite in the 25.4 ka Oruanui supereruption (New Zealand). New data from plagioclase, orthopyroxene, amphibole, quartz, Fe-Ti oxides, matrix glasses, and plagioclase- and quartz-hosted melt inclusions, in samples spanning different phases of the eruption, are integrated with existing data to build a history of the magma system prior to and during eruption. A thermally and compositionally zoned, parental crystal-rich (mush) body was developed during two periods of intensive crystallisation, 70 and 10-15 kyr before the eruption. The mush top was quartz-bearing and as shallow as 3.5 km deep, and the roots quartz-free and extending to >10 km depth. Less than 600 year prior to the eruption, extraction of large volumes of 840 °C low-silica rhyolite melt with some crystal cargo (between 1 and 10%), began from this mush to form a melt-dominant (eruptible) body that eventually extended from 3.5 to 6 km depth. Crystals from all levels of the mush were entrained into the eruptible magma, as seen in mineral zonation and amphibole model pressures. Rapid translation of crystals from the mush to the eruptible magma is reflected in textural and compositional diversity in crystal cores and melt inclusion compositions, versus uniformity in the outermost rims. Prior to eruption the assembled eruptible magma body was not thermally or compositionally zoned and at temperatures of 790 °C, reflecting rapid cooling from the 840 °C low-silica rhyolite feedstock magma. A subordinate but significant volume (3-5 km3) of contrasting tholeiitic and calc-alkaline mafic material was co-erupted with the dominant rhyolite. These mafic clasts host crystals with compositions which demonstrate that there was some limited pre-eruptive physical interaction of mafic

Sulphur-rich volcanic eruptions and stratospheric aerosols

Science.gov (United States)

Rampino, M. R.; Self, S.

1984-01-01

Data from direct measurements of stratospheric optical depth, Greenland ice-core acidity, and volcanological studies are compared, and it is shown that relatively small but sulfur-rich volcanic eruptions can have atmospheric effects equal to or even greater than much larger sulfur-poor eruptions. These small eruptions are probably the most frequent cause of increased stratospheric aerosols. The possible sources of the excess sulfur released in these eruptions are discussed.

Characterization of pyroclastic deposits and pre-eruptive soils following the 2008 eruption of Kasatochi Island Volcano, Alaska

Science.gov (United States)

Wang, B.; Michaelson, G.; Ping, C.-L.; Plumlee, G.; Hageman, P.

2010-01-01

The 78 August 2008 eruption of Kasatochi Island volcano blanketed the island in newly generated pyroclastic deposits and deposited ash into the ocean and onto nearby islands. Concentrations of water soluble Fe, Cu, and Zn determined from a 1:20 deionized water leachate of the ash were sufficient to provide short-term fertilization of the surface ocean. The 2008 pyroclastic deposits were thicker in concavities at bases of steeper slopes and thinner on steep slopes and ridge crests. By summer 2009, secondary erosion had exposed the pre-eruption soils along gulley walls and in gully bottoms on the southern and eastern slopes, respectively. Topographic and microtopographic position altered the depositional patterns of the pyroclastic flows and resulted in pre-eruption soils being buried by as little as 1 m of ash. The different erosion patterns gave rise to three surfaces on which future ecosystems will likely develop: largely pre-eruptive soils; fresh pyroclastic deposits influenced by shallowly buried, pre-eruptive soil; and thick (>1 m) pyroclastic deposits. As expected, the chemical composition differed between the pyroclastic deposits and the pre-eruptive soils. Pre-eruptive soils hold stocks of C and N important for establishing biota that are lacking in the fresh pyroclastic deposits. The pyroclastic deposits are a source for P and K but have negligible nutrient holding capacity, making these elements vulnerable to leaching loss. Consequently, the pre-eruption soils may also represent an important long-term P and K source. ?? 2010 Regents of the University of Colorado.

An interdisciplinary treatment approach combining orthodontic forced eruption with immediate implant placement to achieve a satisfactory treatment outcome: a case report.

Science.gov (United States)

Chou, Yu-Hsiang; Du, Je-Kang; Chou, Szu-Ting; Hu, Kai-Fang; Tsai, Chi-Cheng; Ho, Kun-Yen; Wu, Yi-Min; Ho, Ya-Ping

2013-02-01

Periodontal disease often results in severely bony defects around the teeth and leads to eventual extraction. Remaining bone morphology often compromises ideally restoration-driven positions and deteriorates the success rates for dental implants. The present investigation illustrates the clinical outcome of immediately installing an implant following orthodontic forced eruption and atraumatic extraction. The subject of this study is a 40-year-old Asian female with a right mandibular first molar that had a deep probing depth on the mesial side and mobility. Via the aid of radiographic examination, the tooth that had an angular bony defect and apical lesion was diagnosed as having deep caries and chronic periodontitis with a poor prognosis. After consultation with the patient, we developed a treatment plan incorporating a forced eruption with immediate implantation, intended to augment the alveolar bone volume and increase the width of keratinized gingivae, in a nonsurgical manner. Following 12 months of orthodontic treatment, the tooth was successfully moved occlusally in conjunction with an 8 mm vertical interdental bone augmentation. Because of sufficient volume of bone and satisfactory gingival dimensions, the implant showed adequate initial stability in the correct position to facilitate physiological and aesthetic prerequisites. After 6 months of osteointegration, a customized impression coping was utilized to transfer the established emergence profile to a definitive cast for the fabrication of a customized abutment. The final prosthesis was made using a customized metal abutment and ceramometal crown. In the face of difficult clinical challenges, meticulous inspection and a comprehensive treatment plan were crucial. Interdisciplinary treatment through the careful integration of multiple specialists suggests the possibility of optimal results with high predictability. © 2011 Wiley Periodicals, Inc.

New zircon (U-Th)/He and U/Pb eruption age for the Rockland tephra, western USA

Science.gov (United States)

Coble, Matthew A.; Burgess, Seth D.; Klemetti, Erik W.

2017-09-01

Eruption ages of a number of prominent Quaternary volcanic deposits remain inaccurately and/or imprecisely constrained, despite their importance as regional stratigraphic markers in paleo-environment reconstruction and as evidence of climate-altering eruptions. Accurately dating volcanic deposits presents challenging analytical considerations, including poor radiogenic yield, scarcity of datable minerals, and contamination of crystal populations by magma, eruption, and transport processes. One prominent example is the Rockland tephra, which erupted from the Lassen Volcanic Center in the southern Cascade arc. Despite a range in published eruption ages from 0.40 to 0.63 Ma, the Rockland tephra is extensively used as a marker bed across the western United States. To more accurately and precisely constrain the age of the Rockland tephra-producing eruption, we report U/Pb crystallization dates from the outermost ∼2 μm of zircon crystal faces (surfaces) using secondary ion mass spectrometry (SIMS). Our new weighted mean 238U/206Pb age for Rockland tephra zircon surfaces is 0.598 ± 0.013 Ma (2σ) and MSWD = 1.11 (mean square weighted deviation). As an independent test of the accuracy of this age, we obtained new (U-Th)/He dates from individual zircon grains from the Rockland tephra, which yielded a weighted mean age of 0.599 ± 0.012 Ma (2σ, MSWD = 5.13). We also obtained a (U-Th)/He age of 0.628 ± 0.014 Ma (MSWD = 1.19) for the Lava Creek Tuff member B, which was analyzed as a secondary standard to test the accuracy of the (U-Th)/He technique for Quaternary tephras, and to evaluate assumptions made in the model-age calculation. Concordance of new U/Pb and (U-Th)/He zircon ages reinforces the accuracy of our preferred Rockland tephra eruption age, and confirms that zircon surface dates sample zircon growth up to the time of eruption. We demonstrate the broad applicability of coupled U/Pb zircon-surface and single-grain zircon (U-Th)/He geochronology to accurate

Fitful and protracted magma assembly leading to a giant eruption, Youngest Toba Tuff, Indonesia

Science.gov (United States)

Reid, Mary R; Vazquez, Jorge A.

2017-01-01

The paroxysmal eruption of the 74 ka Youngest Toba Tuff (YTT) of northern Sumatra produced an extraordinary 2800 km3 of non-welded to densely welded ignimbrite and co-ignimbrite ash-fall. We report insights into the duration of YTT magma assembly obtained from ion microprobe U-Th and U-Pb dates, including continuous age spectra over >50% of final zircon growth, for pumices and a welded tuff spanning the compositional range of the YTT. A relatively large subpopulation of zircon crystals nucleated before the penultimate caldera-related eruption at 501 ka, but most zircons yielded interior dates 100-300 ka thereafter. Zircon nucleation and growth was likely episodic and from diverse conditions over protracted time intervals of >100 to >500 ka. Final zircon growth is evident as thin rim plateaus that are in Th/U chemical equilibrium with hosts, and that give crystallization ages within tens of ka of eruption. The longevity and chemical characteristics of the YTT zircons, as well as evidence for intermittent zircon isolation and remobilization associated with magma recharge, is especially favored at the cool and wet eutectoid conditions that characterize at least half of the YTT, wherein heat fluxes could dissolve major phases but have only a minor effect on larger zircon crystals. Repeated magma recharge may have contributed to the development of compositional zoning in the YTT but, considered together with limited allanite, quartz, and other mineral dating and geospeedometry, regular perturbations to the magma reservoir over >400 ka did not lead to eruption until 74 ka ago.

Influence of volatile degassing on the eruptibility of large igneous province magmatic systems

Science.gov (United States)

Mittal, T.; Richards, M. A.

2017-12-01

Magmatic volatiles, in particular their buoyancy, may play a critical role in determining whether a magma reservoir can build up enough overpressure leading to drive flood basalt eruptions (Black & Manga 2017). Thus, it is important to understand the extent to which volatiles can remain trapped in a magmatic system and how they influence the eruptibility. Although the high-temperature metamorphic aureloe around a magma chamber is typically considered to have low permeability due to ductile creep, recent theoretical, experimental, and field work (e.g. Noriaki et al. 2017) have highlighted the role of dynamic permeability in magmatic systems. Consequently, the effective permeability of the crust when magma is present in the system can be orders of magnitude larger than that of exhumed rock samples. We model dynamic permeability changes as a competition between hydro-fracturing (increased porosity) and fracture closure by ductile creep and hydrothermal mineral precipitation (reduced porosity) and find yearly-to-decadal time-scales for periodic fracturing and fluid loss events and an increase in average permeability. We then use a fully coupled poro-thermo-elastic framework to model to explore the macroscopic influence of volatile loss on the stress state of the crust in this higher time-averaged permeability setting. We derive new semi-analytical solutions and combine them with a magma chamber box model (modified from Degruyter & Huber 2014) to analyze system-scale dynamics for both basaltic and silicic magmatic systems. We find that passive degassing likely has a substantial temporal influence on the stress distribution in the crust and the highly crystalline mush zone immediately surrounding a magma reservoir, and find an additional scale : pore-pressure diffusion timescale that exerts a first-order control on the magnitude and frequency of volcanic eruptions. We also explore how disconnected magma batches interact indirectly with each other and its implications for

Rapid laccolith intrusion driven by explosive volcanic eruption.

Science.gov (United States)

Castro, Jonathan M; Cordonnier, Benoit; Schipper, C Ian; Tuffen, Hugh; Baumann, Tobias S; Feisel, Yves

2016-11-23

Magmatic intrusions and volcanic eruptions are intimately related phenomena. Shallow magma intrusion builds subsurface reservoirs that are drained by volcanic eruptions. Thus, the long-held view is that intrusions must precede and feed eruptions. Here we show that explosive eruptions can also cause magma intrusion. We provide an account of a rapidly emplaced laccolith during the 2011 rhyolite eruption of Cordón Caulle, Chile. Remote sensing indicates that an intrusion began after eruption onset and caused severe (>200 m) uplift over 1 month. Digital terrain models resolve a laccolith-shaped body ∼0.8 km 3 . Deformation and conduit flow models indicate laccolith depths of only ∼20-200 m and overpressures (∼1-10 MPa) that likely stemmed from conduit blockage. Our results show that explosive eruptions may rapidly force significant quantities of magma in the crust to build laccoliths. These iconic intrusions can thus be interpreted as eruptive features that pose unique and previously unrecognized volcanic hazards.

The Novarupta-Katmai eruption of 1912 - largest eruption of the twentieth century; centennial perspectives

Science.gov (United States)

Hildreth, Wes; Fierstein, Judy

2012-01-01

The explosive outburst at Novarupta (Alaska) in June 1912 was the 20th century's most voluminous volcanic eruption. Marking its centennial, we illustrate and document the complex eruptive sequence, which was long misattributed to nearby Mount Katmai, and how its deposits have provided key insights about volcanic and magmatic processes. It was one of the few historical eruptions to produce a collapsed caldera, voluminous high-silica rhyolite, wide compositional zonation (51-78 percent SiO2), banded pumice, welded tuff, and an aerosol/dust veil that depressed global temperature measurably. It emplaced a series of ash flows that filled what became the Valley of Ten Thousand Smokes, sustaining high-temperature metal-transporting fumaroles for a decade. Three explosive episodes spanned ~60 hours, depositing ~17 km3 of fallout and 11±2 km3 of ignimbrite, together representing ~13.5 km3 of zoned magma. No observers were nearby and no aircraft were in Alaska, and so the eruption narrative was assembled from scattered villages and ship reports. Because volcanology was in its infancy and the early investigations (1915-23) were conducted under arduous expeditionary conditions, many provocative misapprehensions attended reports based on those studies. Fieldwork at Katmai was not resumed until 1953, but, since then, global advances in physical volcanology and chemical petrology have gone hand in hand with studies of the 1912 deposits, clarifying the sequence of events and processes and turning the eruption into one of the best studied in the world. To provide perspective on this century-long evolution, we describe the geologic and geographic setting of the eruption - in a remote, sparsely inhabited wilderness; we review the cultural and scientific contexts at the time of the eruption and early expeditions; and we compile a chronology of the many Katmai investigations since 1912. Products of the eruption are described in detail, including eight layers of regionwide fallout

Stem cells applications in bone and tooth repair and regeneration: New insights, tools, and hopes.

Science.gov (United States)

Abdel Meguid, Eiman; Ke, Yuehai; Ji, Junfeng; El-Hashash, Ahmed H K

2018-03-01

The exploration of stem and progenitor cells holds promise for advancing our understanding of the biology of tissue repair and regeneration mechanisms after injury. This will also help in the future use of stem cell therapy for the development of regenerative medicine approaches for the treatment of different tissue-species defects or disorders such as bone, cartilages, and tooth defects or disorders. Bone is a specialized connective tissue, with mineralized extracellular components that provide bones with both strength and rigidity, and thus enable bones to function in body mechanical supports and necessary locomotion process. New insights have been added to the use of different types of stem cells in bone and tooth defects over the last few years. In this concise review, we briefly describe bone structure as well as summarize recent research progress and accumulated information regarding the osteogenic differentiation of stem cells, as well as stem cell contributions to bone repair/regeneration, bone defects or disorders, and both restoration and regeneration of bones and cartilages. We also discuss advances in the osteogenic differentiation and bone regeneration of dental and periodontal stem cells as well as in stem cell contributions to dentine regeneration and tooth engineering. © 2017 Wiley Periodicals, Inc.

Multiphoton microscopy imaging of developing tooth germs

Directory of Open Access Journals (Sweden)

Pei-Yu Pan

2014-01-01

Conclusion: In this study, a novel multiphoton microscopy database of images from developing tooth germs in mice was set up. We confirmed that multiphoton laser microscopy is a powerful tool for investigating the development of tooth germ and is worthy for further application in the study of tooth regeneration.

Estimating rates of decompression from textures of erupted ash particles produced by 1999-2006 eruptions of Tungurahua volcano, Ecuador

Science.gov (United States)

Wright, Heather M.N.; Cashman, Katharine V.; Mothes, Patricia A.; Hall, Minard L.; Ruiz, Andrés Gorki; Le Pennec, Jean-Luc

2012-01-01

Persistent low- to moderate-level eruptive activity of andesitic volcanoes is difficult to monitor because small changes in magma supply rates may cause abrupt transitions in eruptive style. As direct measurement of magma supply is not possible, robust techniques for indirect measurements must be developed. Here we demonstrate that crystal textures of ash particles from 1999 to 2006 Vulcanian and Strombolian eruptions of Tungurahua volcano, Ecuador, provide quantitative information about the dynamics of magma ascent and eruption that is difficult to obtain from other monitoring approaches. We show that the crystallinity of erupted ash particles is controlled by the magma supply rate (MSR); ash erupted during periods of high magma supply is substantially less crystalline than during periods of low magma supply. This correlation is most easily explained by efficient degassing at very low pressures (<<50 MPa) and degassing-driven crystallization controlled by the time available prior to eruption. Our data also suggest that the observed transition from intermittent Vulcanian explosions at low MSR to more continuous periods of Strombolian eruptions and lava fountains at high MSR can be explained by the rise of bubbles through (Strombolian) or trapping of bubbles beneath (Vulcanian) vent-capping, variably viscous (and crystalline) magma.

A Radiographic Study of Fused and Geminated Tooth

Energy Technology Data Exchange (ETDEWEB)

Park, Chul Jae; Lee, Sang Rae [Dept. of Oral Radiology, College of Dentistry, Kyunhee University, Seoul (Korea, Republic of)

1990-02-15

The incidence and several characteristic features of fused and geminated teeth were studied radiographically, with full mouth periapical radiogram and pantomogram, in 4201 patients of mixed dentition and 5358 patients of permanent dentition. The obtained results were as follows: 1. The prevalence was revealed to 2.86%, 0.32%, 0.33%, and 0.06% in deciduous fused tooth, permanent fused tooth, deciduous geminated tooth and permanent geminated tooth respectively, and these anomalies were occurred in female more than male. 2. Fused teeth were observed predominantly in lower anterior teeth area, especially in lateral incisor and canine region, and many cases of deciduous geminated tooth were observed in upper central incisor region. 3. Congenital missing rates of succedaneous tooth in deciduous fused teeth were 57.1%, 85.7%, 71.0%, 69.0% in upper right and left central-lateral incisor regions, lower right and left lateral incisor-canine regions, respectively. 4. Prevalence of dental caries was 42.3%, 18.8% and 5.6% in deciduous fused, deciduous geminated and permanent fused tooth, respectively. 5. In classifying of fused and geminated teeth into 9 type, by following appearance such as number of crown, root, pulp chamber and pulp canal of those teeth, it was more favorable that Type I (2 crown, 2 root, 2 pulp chamber, 2 pulp canal) in deciduous fused tooth and Type IX (1 crown, 1 root, 1 pulp chamber, 1 pulp canal) in permanent used tooth, deciduous and permanent geminated tooth.

A Radiographic Study of Fused and Geminated Tooth

International Nuclear Information System (INIS)

Park, Chul Jae; Lee, Sang Rae

1990-01-01

The incidence and several characteristic features of fused and geminated teeth were studied radiographically, with full mouth periapical radiogram and pantomogram, in 4201 patients of mixed dentition and 5358 patients of permanent dentition. The obtained results were as follows: 1. The prevalence was revealed to 2.86%, 0.32%, 0.33%, and 0.06% in deciduous fused tooth, permanent fused tooth, deciduous geminated tooth and permanent geminated tooth respectively, and these anomalies were occurred in female more than male. 2. Fused teeth were observed predominantly in lower anterior teeth area, especially in lateral incisor and canine region, and many cases of deciduous geminated tooth were observed in upper central incisor region. 3. Congenital missing rates of succedaneous tooth in deciduous fused teeth were 57.1%, 85.7%, 71.0%, 69.0% in upper right and left central-lateral incisor regions, lower right and left lateral incisor-canine regions, respectively. 4. Prevalence of dental caries was 42.3%, 18.8% and 5.6% in deciduous fused, deciduous geminated and permanent fused tooth, respectively. 5. In classifying of fused and geminated teeth into 9 type, by following appearance such as number of crown, root, pulp chamber and pulp canal of those teeth, it was more favorable that Type I (2 crown, 2 root, 2 pulp chamber, 2 pulp canal) in deciduous fused tooth and Type IX (1 crown, 1 root, 1 pulp chamber, 1 pulp canal) in permanent used tooth, deciduous and permanent geminated tooth.

Winter warming from large volcanic eruptions

Science.gov (United States)

Robock, Alan; Mao, Jianping

1992-01-01

An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95-percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

Naples between two fires: eruptive scenarios for the next eruptions by an integrated volcanological-probabilistic approach.

Science.gov (United States)

Mastrolorenzo, G.; Pappalardo, L.; de Natale, G.; Troise, C.; Rossano, S.; Panizza, A.

2009-04-01

Probabilistic approaches based on available volcanological data from real eruptions of Campi Flegrei and Somma-Vesuvius, are assembled in a comprehensive assessment of volcanic hazards at the Neapolitan area. This allows to compare the volcanic hazards related to the different types of events, which can be used for evaluating the conditional probability of flows and falls hazard in case of a volcanic crisis. Hazard maps are presented, based on a rather complete set of numerical simulations, produced using field and laboratory data as input parameters relative to a large range (VEI 1 to 5) of fallout and pyroclastic-flow events and their relative occurrence. The results allow us to quantitatively evaluate and compare the hazard related to pyroclastic fallout and density currents (PDCs) at the Neapolitan volcanoes and their surroundings, including the city of Naples. Due to its position between the two volcanic areas, the city of Naples is particularly exposed to volcanic risk from VEI>2 eruptions, as recorded in the local volcanic succession. Because dominant wind directions, the area of Naples is particularly prone to fallout hazard from Campi Flegrei caldera eruptions in the VEI range 2-5. The hazard from PDCs decreases roughly radially with distance from the eruptive vents and is strongly controlled by the topographic heights. Campi Flegrei eruptions are particularly hazardous for Naples, although the Camaldoli and Posillipo hills produce an effective barrier to propagation to the very central part of Naples. PDCs from Vesuvius eruptions with VEI>4 can cover the city of Naples, whereas even VEI>3 eruptions have a moderate fallout hazard there.

Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

Science.gov (United States)

Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

2010-01-01

Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

Eruption probabilities for the Lassen Volcanic Center and regional volcanism, northern California, and probabilities for large explosive eruptions in the Cascade Range

Science.gov (United States)

Nathenson, Manuel; Clynne, Michael A.; Muffler, L.J. Patrick

2012-01-01

Chronologies for eruptive activity of the Lassen Volcanic Center and for eruptions from the regional mafic vents in the surrounding area of the Lassen segment of the Cascade Range are here used to estimate probabilities of future eruptions. For the regional mafic volcanism, the ages of many vents are known only within broad ranges, and two models are developed that should bracket the actual eruptive ages. These chronologies are used with exponential, Weibull, and mixed-exponential probability distributions to match the data for time intervals between eruptions. For the Lassen Volcanic Center, the probability of an eruption in the next year is 1.4x10-4 for the exponential distribution and 2.3x10-4 for the mixed exponential distribution. For the regional mafic vents, the exponential distribution gives a probability of an eruption in the next year of 6.5x10-4, but the mixed exponential distribution indicates that the current probability, 12,000 years after the last event, could be significantly lower. For the exponential distribution, the highest probability is for an eruption from a regional mafic vent. Data on areas and volumes of lava flows and domes of the Lassen Volcanic Center and of eruptions from the regional mafic vents provide constraints on the probable sizes of future eruptions. Probabilities of lava-flow coverage are similar for the Lassen Volcanic Center and for regional mafic vents, whereas the probable eruptive volumes for the mafic vents are generally smaller. Data have been compiled for large explosive eruptions (>≈ 5 km3 in deposit volume) in the Cascade Range during the past 1.2 m.y. in order to estimate probabilities of eruption. For erupted volumes >≈5 km3, the rate of occurrence since 13.6 ka is much higher than for the entire period, and we use these data to calculate the annual probability of a large eruption at 4.6x10-4. For erupted volumes ≥10 km3, the rate of occurrence has been reasonably constant from 630 ka to the present, giving

Analysis of tooth tissues using Raman spectroscopy

International Nuclear Information System (INIS)

Timchenko, E.V.; Timchenko, P.E.; Kulabukhova, A.Yu.; Volova, L.T.; Rosenbaum, A.Yu.

2016-01-01

The results of experimental studies of healthy tooth tissue and tooth tissues during caries disease are presented. Features of Raman spectrum of tooth tissues during caries disease are obtained: the main changes are detected at wavenumbers 956 cm -1 .1069 cm -1 . corresponding to phosphates. and 1241 cm -1 . 1660 cm -1 . corresponding to collagen III and collagen I. respectively. Were introduced criteria allowing to detect caries and to identify weakening of tooth tissues. preceding the caries. The reliability of research results is confirmed by scanning electron microscopy. (paper)

Volcanic Eruptions and Climate

Science.gov (United States)

LeGrande, Allegra N.; Anchukaitis, Kevin J.

2015-01-01

Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

Effect of CPP-ACP on the remineralization of acid-eroded human tooth enamel: nanomechanical properties and microtribological behaviour study

International Nuclear Information System (INIS)

Zheng, L; Zheng, J; Zhang, Y F; Qian, L M; Zhou, Z R

2013-01-01

Casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) has been used to enhance tooth remineralization in the dental clinic. But the contribution of CPP-ACP to the remineralization of acid-eroded human tooth enamel is of widespread controversy. To confirm the application potential of CPP-ACP in the remineralization repair of tooth erosion caused by acid-attack, the effect of remineralization in vitro in 2% w/v CPP-ACP solution on the acid-eroded human tooth enamel was investigated in this study. The repair of surface morphology and the improvement of nanomechanical and microtribological properties were characterized with laser confocal scanning microscope, scanning electron microscope, nanoindentation tester and nanoscratch tester. Results showed that a layer of uneven mineral deposits, which were mainly amorphous calcium phosphate (ACP) in all probability, was observed on the acid-eroded enamel surface after remineralization. Compared with the acid-eroded enamel surface, the nanoindentation hardness and Young's modulus of the remineralized enamel surface obviously increased. Both the friction coefficient and wear volume of the acid-eroded enamel surface decreased after remineralization. However, both the nanomechanical and the anti-wear properties of the remineralized enamel surface were still inferior to those of original enamel surface. In summary, tooth damage caused by acid erosion could be repaired by remineralization in CPP-ACP solution, but the repair effect, especially on the nanomechanical and anti-wear properties of the acid-eroded enamel, was limited. These results would contribute to a further exploration of the remineralization potential of CPP-ACP and a better understanding of the remineralization repair mechanism for acid-eroded human tooth enamel. (paper)

Effect of CPP-ACP on the remineralization of acid-eroded human tooth enamel: nanomechanical properties and microtribological behaviour study

Science.gov (United States)

Zheng, L.; Zheng, J.; Zhang, Y. F.; Qian, L. M.; Zhou, Z. R.

2013-10-01

Casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) has been used to enhance tooth remineralization in the dental clinic. But the contribution of CPP-ACP to the remineralization of acid-eroded human tooth enamel is of widespread controversy. To confirm the application potential of CPP-ACP in the remineralization repair of tooth erosion caused by acid-attack, the effect of remineralization in vitro in 2% w/v CPP-ACP solution on the acid-eroded human tooth enamel was investigated in this study. The repair of surface morphology and the improvement of nanomechanical and microtribological properties were characterized with laser confocal scanning microscope, scanning electron microscope, nanoindentation tester and nanoscratch tester. Results showed that a layer of uneven mineral deposits, which were mainly amorphous calcium phosphate (ACP) in all probability, was observed on the acid-eroded enamel surface after remineralization. Compared with the acid-eroded enamel surface, the nanoindentation hardness and Young's modulus of the remineralized enamel surface obviously increased. Both the friction coefficient and wear volume of the acid-eroded enamel surface decreased after remineralization. However, both the nanomechanical and the anti-wear properties of the remineralized enamel surface were still inferior to those of original enamel surface. In summary, tooth damage caused by acid erosion could be repaired by remineralization in CPP-ACP solution, but the repair effect, especially on the nanomechanical and anti-wear properties of the acid-eroded enamel, was limited. These results would contribute to a further exploration of the remineralization potential of CPP-ACP and a better understanding of the remineralization repair mechanism for acid-eroded human tooth enamel.

Primary culprit for tooth loss!!

Directory of Open Access Journals (Sweden)

Sailavanya Nuvvula

2016-01-01

Full Text Available Aim: In order to facilitate planning for dental health services and to progress strategies to continue the reduction in tooth loss, it is important to identify the factors that result in such loss. therefore the aim of the study is to investigate the major cause for tooth extraction. Objective: to examine whether the major reason for tooth extraction is dental caries or periodontal disease. Materials and Methods: The study is carried out among the dental practitioners in our district. A questionnaire containing 10 items was distributed to the dental practitioners, which included age, gender, no of teeth indicated for extraction, the reason for extraction, and the periodontal parameters that are involved with the extracted tooth and were requested to complete the form on every extraction they were to undertake. the study form was collected at the end of the study period and data was subjected to statistical analysis. Results: A total of 502 patients were enrolled during the study period, and a total of 1055 teeth were extracted for several reasons. we found that 51.14%extractions are due to dental caries in case of 20-30years age groups, which is more when compared to tooth loss due to periodontal diseases in this age group. whereas in case of >40years of age group periodontal diseases account for 54.11%, and dental caries accounts for only 29.11%. Showing more teeth were lost due to periodontal disease. Conclusion: therefore we concluded that, caries is the dominant reason for extraction in patients with 20–30 years of age while periodontal disease accounts for the majority of tooth extraction in patients older than 40 years.

What factors control the size of an eruption?

Science.gov (United States)

Gudmundsson, Agust

2017-04-01

For human society, eruption sizes (eruptive volumes or masses) are of the greatest concern. In particular, the largest eruptions, producing volumes of the order of hundreds or thousands of cubic kilometres, provide, together with meteoritic impacts, the greatest natural threats to mankind. Eruptive volumes tend to follow power laws so that most eruptions are comparatively small whereas a few are very large. It follows that a while during most ruptures of the source chambers a small fraction of the magma leaves the chamber, in some ruptures a very large fraction of the magma leaves the chamber. Most explosive eruptions larger than about 25 km3 are associated with caldera collapse. In the standard 'underpressure' ('lack of magmatic support') model, however, the collapse is the consequence, not the cause, of the large eruption. For poroelastic models, typically less than 4% of the magma in a felsic chamber and less than 0.1% of the magma in a mafic chamber leaves the chamber during rupture (and eventual eruption). In some caldera models, however, 20-70% of the magma is supposed to leave the chamber before the ring-fault forms and the caldera block begins to subside. In these models any amount of magma can flow out of the chamber following its rupture and there is apparently no way to forecast either the volume of magma injected from the chamber (hence the potential size of an eventual eruption) or the conditions for caldera collapse. An alternative model is proposed here. In this model normal (small) eruptions are controlled by standard poroelastity behaviour of the chamber, whereas large eruptions are controlled by chamber-volume reduction or shrinkage primarily through caldera/graben block subsidence into the chamber. Volcanotectonic stresses are then a major cause of ring-fault/graben boundary-fault formation. When large slips occur on these faults, the subsiding crustal block reduces the volume of the underlying chamber/reservoir, thereby maintaining its excess

Interactions between dodecyl phosphates and hydroxyapatite or tooth enamel: relevance to inhibition of dental erosion.

Science.gov (United States)

Jones, Siân B; Barbour, Michele E; Shellis, R Peter; Rees, Gareth D

2014-05-01

Tooth surface modification is a potential method of preventing dental erosion, a form of excessive tooth wear facilitated by softening of tooth surfaces through the direct action of acids, mainly of dietary origin. We have previously shown that dodecyl phosphates (DPs) effectively inhibit dissolution of native surfaces of hydroxyapatite (the type mineral for dental enamel) and show good substantivity. However, adsorbed saliva also inhibits dissolution and DPs did not augment this effect, which suggests that DPs and saliva interact at the hydroxyapatite surface. In the present study the adsorption and desorption of potassium and sodium dodecyl phosphates or sodium dodecyl sulphate (SDS) to hydroxyapatite and human tooth enamel powder, both native and pre-treated with saliva, were studied by high performance liquid chromatography-mass Spectrometry. Thermo gravimetric analysis was used to analyse residual saliva and surfactant on the substrates. Both DPs showed a higher affinity than SDS for both hydroxyapatite and enamel, and little DP was desorbed by washing with water. SDS was readily desorbed from hydroxyapatite, suggesting that the phosphate head group is essential for strong binding to this substrate. However, SDS was not desorbed from enamel, so that this substrate has surface properties different from those of hydroxyapatite. The presence of a salivary coating had little or no effect on adsorption of the DPs, but treatment with DPs partly desorbed saliva; this could account for the failure of DPs to increase the dissolution inhibition due to adsorbed saliva. Copyright © 2014 Elsevier B.V. All rights reserved.

Characteristics of EIT Dimmings in Solar Eruptions

Science.gov (United States)

Adams, Mitzi; Sterling, A. C.

2006-01-01

Intensity "dimmings" in coronal images are a key feature of solar eruptions. Such dimmings are likely the source locations for much of the material expelled in coronal mass ejections (CMEs). Characteristics such as the timing of the dimmings with respect to the onset of other eruption signatures, and the location of the dimmings in the context of the magnetic field environment of the erupting region, are indicative of the mechanism leading to the eruption. We examine dimmings of six eruptions in images from the EUV Imaging Telescope (EIT) on SOHO, along with supplementary soft X-ray (SXR) data from GOES and the SXR Telescope (SXT) on Yohkoh. We examine the timing of the dimming onset and compare with the time of EUV and SXR brightening and determine the timescale for the recovery from dimming for each event. With line-of-sight photospheric magnetograms from the MDI instrument on SOHO, we determine the magnetic structure of the erupting regions and the locations of the dimmings in those regions. From our analysis we consider which mechanism likely triggered each eruption: internal tether cutting, external tether cutting ("breakout"), loss of equilibrium, or some other mechanism.

Plasma Evolution within an Erupting Coronal Cavity

Science.gov (United States)

Long, David M.; Harra, Louise K.; Matthews, Sarah A.; Warren, Harry P.; Lee, Kyoung-Sun; Doschek, George A.; Hara, Hirohisa; Jenkins, Jack M.

2018-03-01

Coronal cavities have previously been observed to be associated with long-lived quiescent filaments and are thought to correspond to the associated magnetic flux rope. Although the standard flare model predicts a coronal cavity corresponding to the erupting flux rope, these have only been observed using broadband imaging data, restricting an analysis to the plane-of-sky. We present a unique set of spectroscopic observations of an active region filament seen erupting at the solar limb in the extreme ultraviolet. The cavity erupted and expanded rapidly, with the change in rise phase contemporaneous with an increase in nonthermal electron energy flux of the associated flare. Hot and cool filamentary material was observed to rise with the erupting flux rope, disappearing suddenly as the cavity appeared. Although strongly blueshifted plasma continued to be observed flowing from the apex of the erupting flux rope, this outflow soon ceased. These results indicate that the sudden injection of energy from the flare beneath forced the rapid eruption and expansion of the flux rope, driving strong plasma flows, which resulted in the eruption of an under-dense filamentary flux rope.

The combination use of platelet-rich fibrin and treated dentin matrix for tooth root regeneration by cell homing.

Science.gov (United States)

Ji, Baohui; Sheng, Lei; Chen, Gang; Guo, Shujuan; Xie, Li; Yang, Bo; Guo, Weihua; Tian, Weidong

2015-01-01

Endogenous regeneration through cell homing provides an alternative approach for tissue regeneration, except cell transplantation, especially considering clinical translation. However, tooth root regeneration through cell homing remains a provocative approach in need of intensive study. Both platelet-rich fibrin (PRF) and treated dentin matrix (TDM) are warehouses of various growth factors, which can promote cell homing. We hypothesized that endogenous stem cells are able to sense biological cues from PRF membrane and TDM, and contribute to the regeneration of tooth root, including soft and hard periodontal tissues. Therefore, the biological effects of canine PRF and TDM on periodontal ligament stem cells (PDLSCs) and bone marrow mesenchymal stem cells (BMSCs) were evaluated respectively in vitro. Beagle dogs were used as orthotopic transplantation model. It was found that PRF significantly recruited and stimulated the proliferation of PDLSCs and BMSCs in vitro. Together, PRF and TDM induced cell differentiation by upregulating the mineralization-related gene expression of bone sialoprotein (BSP) and osteopotin (OPN) after 7 days coculture. In vivo, transplantation of autologous PRF and allogeneic TDM into fresh tooth extraction socket achieved successful root regeneration 3 months postsurgery, characterized by the regeneration of cementum and periodontal ligament (PDL)-like tissues with orientated fibers, indicative of functional restoration. The results suggest that tooth root connected to the alveolar bone by cementum-PDL complex can be regenerated through the implantation of PRF and TDM in a tooth socket microenvironment, probably by homing of BMSCs and PDLSCs. Furthermore, bioactive cues and inductive microenvironment are key factors for endogenous regeneration. This approach provides a tangible pathway toward clinical translation.

The role of magma mixing/mingling and cumulate melting in the Neapolitan Yellow Tuff caldera-forming eruption (Campi Flegrei, Southern Italy)

Science.gov (United States)

Forni, Francesca; Petricca, Eleonora; Bachmann, Olivier; Mollo, Silvio; De Astis, Gianfilippo; Piochi, Monica

2018-06-01

Understanding the mechanisms responsible for the generation of chemical gradients in high-volume ignimbrites is key to retrieve information on the processes that control the maturation and eruption of large silicic magmatic reservoirs. Over the last 60 ky, two large ignimbrites showing remarkable zoning were emplaced during caldera-forming eruptions at Campi Flegrei (i.e., Campanian Ignimbrite, CI, 39 ka and Neapolitan Yellow Tuff, NYT, 15 ka). While the CI displays linear compositional, thermal and crystallinity gradients, the NYT is a more complex ignimbrite characterized by crystal-poor magmas ranging in composition from trachy-andesites to phonolites. By combining major and trace element compositions of matrix glasses and mineral phases from juvenile clasts located at different stratigraphic heights along the NYT pyroclastic sequence, we interpret such compositional gradients as the result of mixing/mingling between three different magmas: (1) a resident evolved magma showing geochemical characteristics of a melt extracted from a cumulate mush dominated by clinopyroxene, plagioclase and oxides with minor sanidine and biotite; (2) a hotter and more mafic magma from recharge providing high-An plagioclase and high-Mg clinopyroxene crystals and (3) a compositionally intermediate magma derived from remelting of low temperature mineral phases (i.e., sanidine and biotite) within the cumulate crystal mush. We suggest that the presence of a refractory crystal mush, as documented by the occurrence of abundant crystal clots containing clinopyroxene, plagioclase and oxides, is the main reason for the lack of erupted crystal-rich material in the NYT. A comparison between the NYT and the CI, characterized by both crystal-poor extracted melts and crystal-rich magmas representing remobilized portions of a "mature" (i.e., sanidine dominated) cumulate residue, allows evaluation of the capability of crystal mushes of becoming eruptible upon recharge.

Pattern of drug eruptions in a tertiary care hospital

International Nuclear Information System (INIS)

Tahir, Z.; Nadeem, N.; Aman, S.; Kazmi, A.H.

2013-01-01

Background: An adverse drug reaction is unintentional which occurs at doses used for prophylaxis, diagnosis or treatment. Objectives: To determine the frequency of various cutaneous drug eruptions that occur in patients in a tertiary care hospital setting. Patients and Methods: All patients with cutaneous drug eruptions seen at the Dermatology Department of Mayo Hospital, Lahore, over 6 months were enrolled and the pattern of drug eruptions like urticaria, angioedema, fixed drug eruption, maculopapular rash, erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis etc. were recorded, along with drugs that caused it. Results:A total of 160 patients (86 males, 74 females) were included in the study. Mean age of patients was 30.7+-15.4 years. Major eruptions were fixed drug eruption (21.3%) followed by urticaria without angioedema (10%), maculopapular rash (9.3%), lichenoid drug eruption (8.7%), acneiform drug eruption (7.5%), Stevens-Johnson syndrome (6.9%), vesiculobullous eruption (5.6%), erythema multiforme and eczematous eruption (5% each). Common drugs causing eruptions were sulfonamides (16.3%), followed by NSAIDs (14.4%), herbal and homeopathic medications (12.5%), penicillins (9.3%), tetracyclines (8.7%), antituberculous drugs, cephalosporins and antiepileptics (6.3% each). Conclusion: Fixed drug eruption and urticaria without angioedema were commonest eruptions while, sulfonamides and NSAIDs were the major causative drugs. Policy message: Reporting of adverse drug reactions is not done in Pakistan and needs to be done in each hospital. (author)

[Effects of tooth whitening agents and acidic drinks on the surface properties of dental enamel].

Science.gov (United States)

Chen, Xiaoling; Chen, Zhiqun; Lin, Yao; Shao, Jinquan; Yin, Lu

2013-10-01

Using tooth whitening agents (bleaching clip) in vitro and acidic drinks, we conducted a comparative study of the changes in enamel surface morphology, Ca/P content, and hardness. Tooth whitening glue pieces, cola, and orange juice were used to soak teeth in artificial saliva in vitro. Physiological saline was used as a control treatment. The morphology of the four groups was observed under a scanning electron microscope (SEM) immediately after the teeth were soaked for 7 and 14 d. The changes in Ca/P content and microhardness were analyzed. The enamel surfaces of the teeth in the three test groups were demineralized. The Ca/P ratio and the average microhardness were significantly lower than those of the control group immediately after the teeth were soaked (P 0.05). Bleaching agents caused transient demineralization of human enamel, but these agents could induce re-mineralization and repair of enamel over time. Demineralization caused by bleaching covered a relatively normal range compared with acidic drinks and daily drinking.

Seasonal variations of volcanic eruption frequencies

Science.gov (United States)

Stothers, Richard B.

1989-01-01

Do volcanic eruptions have a tendency to occur more frequently in the months of May and June? Some past evidence suggests that they do. The present study, based on the new eruption catalog of Simkin et al.(1981), investigates the monthly statistics of the largest eruptions, grouped according to explosive magnitude, geographical latitude, and year. At the 2-delta level, no month-to-month variations in eruption frequency are found to be statistically significant. Examination of previously published month-to-month variations suggests that they, too, are not statistically significant. It is concluded that volcanism, at least averaged over large portions of the globe, is probably not periodic on a seasonal or annual time scale.

The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption

OpenAIRE

Klügel, Andreas; Hoernle, Kaj A.; Schmincke, Hans-Ulrich; White, James D. L.

2000-01-01

The 1949 rift zone eruption along the Cumbre Vieja ridge on La Palma involved three eruptive centers, 3 km spaced apart, and was chemically and mineralogically zoned. Duraznero crater erupted tephrite for 14 days and shut down upon the opening of Llano del Banco, a fissure that issued first tephrite and, after 3 days, basanite. Hoyo Negro crater opened 4 days later and erupted basanite, tephrite, and phonotephrite, while Llano del Banco continued to issue basanite. The eruption ended with Dur...

Tooth wear and wear investigations in dentistry.

Science.gov (United States)

Lee, A; He, L H; Lyons, K; Swain, M V

2012-03-01

Tooth wear has been recognised as a major problem in dentistry. Epidemiological studies have reported an increasing prevalence of tooth wear and general dental practitioners see a greater number of patients seeking treatment with worn dentition. Although the dental literature contains numerous publications related to management and rehabilitation of tooth wear of varying aetiologies, our understanding of the aetiology and pathogenesis of tooth wear is still limited. The wear behaviour of dental biomaterials has also been extensively researched to improve our understanding of the underlying mechanisms and for the development of restorative materials with good wear resistance. The complex nature of tooth wear indicates challenges for conducting in vitro and in vivo wear investigations and a clear correlation between in vitro and in vivo data has not been established. The objective was to critically review the peer reviewed English-language literature pertaining to prevalence and aetiology of tooth wear and wear investigations in dentistry identified through a Medline search engine combined with hand-searching of the relevant literature, covering the period between 1960 and 2011. © 2011 Blackwell Publishing Ltd.

Setting of the Father's Day Eruption at Kilauea

Science.gov (United States)

Swanson, D. A.

2007-12-01

The Father's Day eruption and associated intrusion took place within a 10-km segment of Kilauea's east rift zone between Hi`iaka and Napau Craters--a segment that has had more numerous eruptions and intrusions than any other of comparable length during the past 200, probably the past 1000, years. Fifteen known eruptions started in this area in the past 200 years: 1840, 1922, 1923, 1962, August and October 1963, March and December 1965, August and October 1968, February and May 1969, May and November 1973, and March 1980 (only 3 cubic meters!). Three others, not previously designated as distinct eruptions despite having all the appropriate characteristics, took place during on-going eruptions: two in `Alo`i Crater in 1970 and 1972, and one in Napau Crater in 1997. Two of the largest shields on the east rift zone formed during long-lasting eruptions within this area--Kane Nui o Hamo at an unknown date, perhaps the 11-12th century, and Mauna Ulu (1969-1974). In addition, many small intrusions without eruptions are known. Seven short eruptions punctuated a prolonged eruption: four within the segment during the Mauna Ulu eruption, two at the summit and southwest rift zone during that same eruption, and one in Napau Crater in 1997 during the Pu`u `O`o eruption. Thus the Father's Day eruption is not unique by virtue of taking place during an ongoing eruption elsewhere along the rift zone. The increased frequency of activity in the segment during the 20th century is obvious, particularly after 1962. For most of the past 1,000 years, eruptions were centered at Kilauea's summit, with significant but lesser activity along the rift zones. A large summit deflation in 1924 ended the nearly continuous lava lake in Halemaumau, eventually leading to the past 5 decades of dominantly east rift zone activity. This segment of the rift zone contains most of the pit craters on Kilauea and gradually changes from a SE trend near the caldera to an ENE trend that characterizes the rest of

Analysis of the relationships between edentulism, periodontal health, body composition, and bone mineral density in elderly women

Directory of Open Access Journals (Sweden)

Ignasiak Z

2016-03-01

Full Text Available Zofia Ignasiak,1 Malgorzata Radwan-Oczko,2 Krystyna Rozek-Piechura,3 Marta Cholewa,4 Anna Skrzek,5 Tomasz Ignasiak,6 Teresa Slawinska1 1Department of Biostructure, University School of Physical Education, Wroclaw, Poland; 2Department of Periodontology, Wroclaw Medical University, Wroclaw, Poland; 3Department of Physiotherapy and Occupation Therapy in Internal Diseases, University School of Physical Education, Wroclaw, Poland; 4DENTARAMA Dentistry Center, Walbrzych, Poland; 5Department of Physiotherapy and Ocupation Therapy in Motor-System Dysfunction, University School of Physical Education, Wroclaw, Poland; 6Karkonosze State Higher School in Jelenia Gora, Jelenia Gora, Poland Objective: The relationship between bone mineral density (BMD and tooth loss in conjunction with periodontal disease is not clear. The suggested effects include alteration in bone remodeling rates as well as the multifaceted etiology of edentulism. There is also a question if other body-related variables besides BMD, such as body composition, may be associated with tooth number and general periodontal health. The aim of this study was to evaluate if tooth number and marginal periodontal status are associated with body composition and BMD in a sample of elderly women. Materials and methods: The study involved 91 postmenopausal women. Data included basic anthropometric characteristics, body composition via bioelectrical impedance analysis, and BMD analysis at the distal end of the radial bone of the nondominant arm via peripheral dual-energy X-ray absorptiometry. A dental examination was performed to assess tooth number, periodontal pocket depth (PD, and gingival bleeding. Results: In nonosteoporotic women, a significant positive correlation was found between BMD and lean body mass, total body water, and muscle mass. The indicators of bone metabolism correlated negatively with PD. Such relationships did not appear in osteoporotic women. In both groups, basic anthropometric

Is tooth wear in the primary dentition predictive of tooth wear in the permanent dentition? Report from a longitudinal study.

LENUS (Irish Health Repository)

Harding, M A

2010-03-01

To determine the prevalence of tooth wear in the permanent dentition of a sample of 12-year-old school children and establish whether an association exists between tooth wear recorded now and tooth wear recorded in their primary dentition at age five.

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

Science.gov (United States)

Zazzo, A.; Balasse, M.; Passey, B. H.; Moloney, A. P.; Monahan, F. J.; Schmidt, O.

2010-06-01

Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite ( ɛD-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO 2 performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M 1) and second (M 2) lower molars of four lambs as well as on the third lower molar (M 3) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M 1, and 4 months in M 2 and M 3. Portions of enamel in equilibrium with dietary carbon were used to calculate ɛD-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth

SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeongwoo; Chae, Jongchul [Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of); Liu, Chang; Jing, Ju [Space Weather Research Laboratory, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

2016-09-20

How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encircling the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.

SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

International Nuclear Information System (INIS)

Lee, Jeongwoo; Chae, Jongchul; Liu, Chang; Jing, Ju

2016-01-01

How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encircling the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.

The Ottaviano eruption of Somma-Vesuvio (8000 y B.P.): a magmatic alternating fall and flow-forming eruption

Science.gov (United States)

Rolandi, G.; Maraffi, S.; Petrosino, P.; Lirer, L.

1993-11-01

The Ottaviano eruption occurred in the late neolithic (8000 y B.P.). 2.40 km 3 of phonolitic pyroclastic material (0.61 km 3 DRE) were emplaced as pyroclastic flow, surge and fall deposits. The eruption began with a fall phase, with a model column height of 14 km, producing a pumice fall deposit (LA). This phase ended with short-lived weak explosive activity, giving rise to a fine-grained deposit (L1), passing to pumice fall deposits as the result of an increasing column height and mass discharge rate. The subsequent two fall phases (producing LB and LC deposits), had model column heights of 20 and 22 km with eruption rates of 2.5 × 10 7 and 2.81 × 10 7 kg/s, respectively. These phases ended with the deposition of ash layers (L2 and L3), related to a decreasing, pulsing explosive activity. The values of dynamic parameters calculated for the eruption classify it as a sub-plinian event. Each fall phase was characterized by variations in the eruptive intensity, and several pyroclastic flows were emplaced (F1 to F3). Alternating pumice and ash fall beds record the waning of the eruption. Finally, owing to the collapse of a eruptive column of low gas content, the last pyroclastic flow (F4) was emplaced.

Eruption dynamics and explosive-effusive transitions during the 1400 cal BP eruption of Opala volcano, Kamchatka, Russia

Science.gov (United States)

Andrews, Benjamin J.; Dufek, Josef; Ponomareva, Vera

2018-05-01

Deposits and pumice from the 1400 cal BP eruption of Opala volcano record activity that occurred at the explosive-effusive transition, resulting in intermittent, or stop-start, behavior, where explosive activity resumed following a pause. The eruption deposited distinctive, biotite-bearing rhyolite tephra across much of Kamchatka, and its stratigraphy consists of a lithic-rich pumice fall, overlain by pumice falls and pyroclastic density deposits, with the proportion of the latter increasing with height. This sequence repeats such that the middle of the total deposit is marked by a lithic-rich fall with abundant obsidian clasts. Notably, the eruptive pumice are poorly vesiculated, with vesicle textures that record fragmentation of a partially collapsed magmatic foam. The eruption vent, Baranii Amphitheater is filled with obsidian lavas of the same composition as the rhyolite tephra. Based upon the stratigraphic and compositional relations, we divide the eruption into four phases. Phase I initiated with eruption of a lithic-rich pumice fall, followed by eruption of Plinian falls and pyroclastic density currents. During Phase II, the eruption paused for at least 5-6 h; in this time, microlites nucleated and began to grow in the magma. Phase III essentially repeated the Phase I sequence. Obsidian lavas were emplaced during Phase IV. The pumice textures suggest that the magma ascended very near the threshold decompression rate for the transition between explosive (fast) and effusive (slow) behavior. The pause during Phase II likely occurred as decompression slowed enough for the magma to develop sufficient permeability for gas to escape resulting in collapse of the magmatic foam, stopping the eruption and temporarily sealing the conduit. After about 5-6 h, eruption resumed with, once again, magma decompressing very near the explosive-effusive transition. Phase III ended when the decompression rate slowed and lava dome emplacement began. Distributions of pumice and

The 2008 Eruption of Chaitén Volcano, Chile and National Volcano-Monitoring Programs in the U.S. and Chile

Science.gov (United States)

Ewert, J. W.; Lara, L. E.; Moreno, H.

2008-12-01

Chaitén volcano, southern Chile, began erupting on 2 May 2008. The eruption produced 3 Plinian eruption pulses between May 2 and 8. Between Plinian phases the volcano emitted a constant column of ash to approximately 10 km, gradually diminishing to approximately 3 km by the end of June. The eruption of Chaitén was remarkable on several counts--it was the first rhyolite eruption on the planet since Novarupta (Katmai) erupted in 1912, and Chaitén had apparently lain dormant for approximately 9300 years. Though Chaitén is located in a generally sparsely populated region, the eruption had widespread impacts. More than 5000 people had to be quickly evacuated from proximal areas and aviation in southern South America was disrupted for weeks. Within 10 days secondary lahars had overrun much of the town of Chaitén complicating the prospects of the townspeople to return to their homes. Prior to the eruption onset, the nearest real-time seismic station was 300 km distant, and earthquakes were not felt by local citizens until approximately 30 hours before the eruption onset. No other signs of unrest were noted. Owing to the lack of near-field monitoring, and the nighttime eruption onset, there was initial confusion about which volcano was erupting: Chaitén or nearby Michinmahuida. Lack of monitoring systems at Chaitén meant that warning time for the public at risk was extremely short, and owing to the nature of the eruption and the physical geography of the area, it was very difficult to install monitoring instruments to track its progress after the eruption started. The lack of geophysical monitoring also means that an important data set on precursory behavior for silicic systems was not collected. With more than 120 Pleistocene to Holocene-age volcanoes within its continental territory, Chile is one of the more volcanically active countries in the world. The eruption of Chaitén has catalyzed the creation of a new program within the Servicio Nacional de Geología y

Stress field control during large caldera-forming eruptions

Directory of Open Access Journals (Sweden)

Antonio Costa

2016-10-01

Full Text Available Crustal stress field can have a significant influence on the way magma is channelled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs can erupt hundreds to thousands of cubic kilometres of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 109 - 1011 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a magma chamber that in turn is fed by a deeper magma reservoir, both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

Volcanic eruptions are cooling the earth

International Nuclear Information System (INIS)

Groenaas, Sigbjoern

2005-01-01

The article discusses how volcanic eruptions may influence the climate. The environmental impacts both on the earth surface and the atmosphere are surveyed. Some major eruptions in modern times are mentioned

Clinical Evaluation of Periodontal Tissue Status in Prosthodontic Treatment of Patients with Partial Tooth Loss and Generalized Periodontitis

Directory of Open Access Journals (Sweden)

A. Kushlyk

2018-01-01

. Results and discussion. The application of direct dental prosthetic rehabilitation method after mobile tooth removal in combination treatment of generalized periodontitis allows stabilizing degenerative and inflammatory processes in the periodontium in the initial stages, as well as increasing the resistance of the capillaries and bone mineral density of the interdental septa. The obtained data indicated that the application of the proposed direct fixed sectional dental bridge was more effective as compared to conventional prosthetics methods. Conclusions. 1. Direct fixed prosthodontics using direct fixed sectional dental bridge is essential in combination treatment of generalized periodontitis, especially if mobile tooth extraction is needed. It allows increasing the effectiveness of treatment in comparison with direct removable prosthodontics using direct plastic laminar immediate prosthesis (Group I and traditional treatment methods (Group II. 2. We have proved the advantages of direct fixed prosthodontics in treatment of patients with generalized periodontitis, II-III degree based on the improvement of oral hygiene indices, the gingival bleeding index, the papillary-marginal-alveolar index, the periodontal index and the depth of periodontal pockets 6-12 months after treatment.

Biologically Based Restorative Management of Tooth Wear

Directory of Open Access Journals (Sweden)

Martin G. D. Kelleher

2012-01-01

Full Text Available The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles.

The June 2014 eruption at Piton de la Fournaise: Robust methods developed for monitoring challenging eruptive processes

Science.gov (United States)

Villeneuve, N.; Ferrazzini, V.; Di Muro, A.; Peltier, A.; Beauducel, F.; Roult, G. C.; Lecocq, T.; Brenguier, F.; Vlastelic, I.; Gurioli, L.; Guyard, S.; Catry, T.; Froger, J. L.; Coppola, D.; Harris, A. J. L.; Favalli, M.; Aiuppa, A.; Liuzzo, M.; Giudice, G.; Boissier, P.; Brunet, C.; Catherine, P.; Fontaine, F. J.; Henriette, L.; Lauret, F.; Riviere, A.; Kowalski, P.

2014-12-01

After almost 3.5 years of quiescence, Piton de la Fournaise (PdF) produced a small summit eruption on 20 June 2014 at 21:35 (GMT). The eruption lasted 20 hours and was preceded by: i) onset of deep eccentric seismicity (15-20 km bsl; 9 km NW of the volcano summit) in March and April 2014; ii) enhanced CO2 soil flux along the NW rift zone; iii) increase in the number and energy of shallow (shallow location, was not characteristic of an eruptive crisis. However, at 20:06 on 20/06 their character changed. This was 74 minutes before the onset of tremor. Deformations then began at 20:20. Since 2007, PdF has emitted small magma volumes (processing of seismic data, borehole tiltmeters and permanent monitoring of summit gas emissions, plus CO2 soil flux, were used to track precursory activity. JERK, based on an analysis of the acceleration slope of a broad-band seismometer data, allowed advanced notice of the new eruption by 50 minutes. MSNoise, based on seismic velocity determination, showed a significant decrease 7 days before the eruption. These signals were coupled with change in summit fumarole composition. Remote sensing allowed the following syn-eruptive observations: - INSAR confirmed measurements made by the OVPF geodetic network, showing that deformation was localized around the eruptive fissures; - A SPOT5 image acquired at 05:41 on 21/06 allowed definition of the flow field area (194 500 m2); - A MODIS image acquired at 06:35 on 21/06 gave a lava discharge rate of 6.9±2.8 m3 s-1, giving an erupted volume of 0.3 and 0.4 Mm3. - This rate was used with the DOWNFLOW and FLOWGO models, calibrated with the textural data from Piton's 2010 lava, to run lava flow projections; showing that the event was volume limited. Preliminary sample analyses suggest that the olivine rich lavas have a differentiated character (melt MgO: 5.8 - 6.2 wt.%); proof of chamber residence. However, some aphyric tephra are more primitive (MgO: 8.2 wt.%). This suggests eruption due to

The frequency of explosive volcanic eruptions in Southeast Asia.

Science.gov (United States)

Whelley, Patrick L; Newhall, Christopher G; Bradley, Kyle E

There are ~750 active and potentially active volcanoes in Southeast Asia. Ash from eruptions of volcanic explosivity index 3 (VEI 3) and smaller pose mostly local hazards while eruptions of VEI ≥ 4 could disrupt trade, travel, and daily life in large parts of the region. We classify Southeast Asian volcanoes into five groups, using their morphology and, where known, their eruptive history and degassing style. Because the eruptive histories of most volcanoes in Southeast Asia are poorly constrained, we assume that volcanoes with similar morphologies have had similar eruption histories. Eruption histories of well-studied examples of each morphologic class serve as proxy histories for understudied volcanoes in the class. From known and proxy eruptive histories, we estimate that decadal probabilities of VEI 4-8 eruptions in Southeast Asia are nearly 1.0, ~0.6, ~0.15, ~0.012, and ~0.001, respectively.

Cross-talk between Msx/Dlx homeobox genes and vitamin D during tooth mineralization.

Science.gov (United States)

Lézot, F; Descroix, V; Mesbah, M; Hotton, D; Blin, C; Papagerakis, P; Mauro, N; Kato, S; MacDougall, M; Sharpe, P; Berdal, A

2002-01-01

Rickets is associated with site-specific disorders of enamel and dentin formation, which may reflect the impact of vitamin D on a morphogenetic pathway. This study is devoted to potential cross-talk between vitamin D and Msx/Dlx transcription factors. We raised the question of a potential link between tooth defects seen in mice with rickets and Msx2 gene misexpression, using mutant mice lacking the nuclear vitamin D receptor as an animal model. Our data showed a modulation of Msx2 expression. In order to search for a functional impact of this Msx2 misexpression secondary to rickets, we focused our attention on osteocalcin as a target gene for both vitamin D and Msx2. Combining Msx2 overexpression and vitamin D addition in vitro, we showed an inhibitory effect on osteocalcin expression in immortalized MO6-G3 odontoblasts. Finally, in the same cells, such combinations appeared to modulate VDR expression outlining the existence of complex cross-regulations between vitamin D and Msx/Dix pathways.

Fragile X syndrome: panoramic radiographic evaluation of dental anomalies, dental mineralization stage, and mandibular angle

Science.gov (United States)

Sabbagh-Haddad, Aida; Haddad, Denise Sabbagh; Michel-Crosato, Edgard; Arita, Emiko Saito

2016-01-01

ABSTRACT Fragile X syndrome (FXS) is a disorder linked to the chromosome X long arm (Xq27.3), which is identified by a constriction named fragile site. It determines various changes, such as behavioral or emotional problems, learning difficulties, and intellectual disabilities. Craniofacial abnormalities such as elongated and narrow face, prominent forehead, broad nose, large and prominent ear pavilions, strabismus, and myopia are frequent characteristics. Regarding the oral aspects, deep and high-arched palate, mandibular prognathism, and malocclusion are also observed. Objective: The purpose of this study was to evaluate the dental radiographic characteristics as described in 40 records of patients with panoramic radiography. Material and Methods: The patients were in the range of 6–17 years old, and were divided into two groups (20 subjects who were compatible with the normality standard and 20 individuals diagnosed with the FXS), which were matched for gender and age. Analysis of the panoramic radiographic examination involved the evaluation of dental mineralization stage, mandibular angle size, and presence of dental anomalies in both deciduous and permanent dentitions. Results: The results of radiographic evaluation demonstrated that the chronology of tooth eruption of all third and second lower molars is anticipated in individuals with FXS (pdental anomalies. In addition, an increase was observed in the mandibular angle size in the FXS group (pdental radiographic changes is of great importance for dental surgeons to plan the treatment of these individuals. PMID:27812623

Impacts of a Pinatubo-size volcanic eruption on ENSO

KAUST Repository

Predybaylo, Evgeniya

2017-01-16

Observations and model simulations of the climate responses to strong explosive low-latitude volcanic eruptions suggest a significant increase in the likelihood of El Niño during the eruption and posteruption years, though model results have been inconclusive and have varied in magnitude and even sign. In this study, we test how this spread of responses depends on the initial phase of El Niño-Southern Oscillation (ENSO) in the eruption year and on the eruption\\'s seasonal timing. We employ the Geophysical Fluid Dynamics Laboratory CM2.1 global coupled general circulation model to investigate the impact of the Pinatubo 1991 eruption, assuming that in 1991 ENSO would otherwise be in central or eastern Pacific El Niño, La Niña, or neutral phases. We obtain statistically significant El Niño responses in a year after the eruption for all cases except La Niña, which shows no response in the eastern equatorial Pacific. The eruption has a weaker impact on eastern Pacific El Niños than on central Pacific El Niños. We find that the ocean dynamical thermostat and (to a lesser extent) wind changes due to land-ocean temperature gradients are the main feedbacks affecting El Niño development after the eruption. The El Niño responses to eruptions occurring in summer are more pronounced than for winter and spring eruptions. That the climate response depends on eruption season and initial ENSO phase may help to reconcile apparent inconsistencies among previous studies.

Geomorphic consequences of volcanic eruptions in Alaska: A review

Science.gov (United States)

Waythomas, Christopher F.

2015-01-01

Eruptions of Alaska volcanoes have significant and sometimes profound geomorphic consequences on surrounding landscapes and ecosystems. The effects of eruptions on the landscape can range from complete burial of surface vegetation and preexisting topography to subtle, short-term perturbations of geomorphic and ecological systems. In some cases, an eruption will allow for new landscapes to form in response to the accumulation and erosion of recently deposited volcaniclastic material. In other cases, the geomorphic response to a major eruptive event may set in motion a series of landscape changes that could take centuries to millennia to be realized. The effects of volcanic eruptions on the landscape and how these effects influence surface processes has not been a specific focus of most studies concerned with the physical volcanology of Alaska volcanoes. Thus, what is needed is a review of eruptive activity in Alaska in the context of how this activity influences the geomorphology of affected areas. To illustrate the relationship between geomorphology and volcanic activity in Alaska, several eruptions and their geomorphic impacts will be reviewed. These eruptions include the 1912 Novarupta–Katmai eruption, the 1989–1990 and 2009 eruptions of Redoubt volcano, the 2008 eruption of Kasatochi volcano, and the recent historical eruptions of Pavlof volcano. The geomorphic consequences of eruptive activity associated with these eruptions are described, and where possible, information about surface processes, rates of landscape change, and the temporal and spatial scale of impacts are discussed.A common feature of volcanoes in Alaska is their extensive cover of glacier ice, seasonal snow, or both. As a result, the generation of meltwater and a variety of sediment–water mass flows, including debris-flow lahars, hyperconcentrated-flow lahars, and sediment-laden water floods, are typical outcomes of most types of eruptive activity. Occasionally, such flows can be quite

Near-surface structural examination of human tooth enamel subject to in vitro demineralization and remineralization

Science.gov (United States)

Gaines, Carmen Veronica

The early stages of chemical tooth decay are governed by dynamic processes of demineralization and remineralization of dental enamel that initiates along the surface of the tooth. Conventional diagnostic techniques lack the spatial resolution required to analyze near-surface structural changes in enamel at the submicron level. In this study, slabs of highly-polished, decay-free human enamel were subjected to 0.12M EDTA and buffered lactic acid demineralizing agents and MI Paste(TM) and calcifying (0.1 ppm F) remineralizing treatments in vitro. Grazing incidence x-ray diffraction (GIXD), a technique typically used for thin film analysis, provided depth profiles of crystallinity changes in surface enamel with a resolution better than 100 nm. In conjunction with nanoindentation, a technique gaining acceptance as a means of examining the mechanical properties of sound enamel, these results were corroborated with well-established microscopy and Raman techniques to assess the nanohardness, morphologies and chemical nature of treated enamel. Interestingly, the average crystallite size of surface enamel along its c-axis dimension increased by nearly 40% after a 60 min EDTA treatment as detected by GIXD. This result was in direct contrast to the obvious surface degradation observed by microscopic and confocal Raman imaging. A decrease in nanohardness from 4.86 +/- 0.44 GPa to 0.28 +/- 0.10 GPa was observed. Collective results suggest that mineral dissolution characteristics evident on the micron scale may not be fully translated to the nanoscale in assessing the integrity of chemically-modified tooth enamel. While an intuitive decrease in enamel crystallinity was observed with buffered lactic acid-treated samples, demineralization was too slow to adequately quantify the enamel property changes seen. MI Paste(TM) treatment of EDTA-demineralized enamel showed preferential growth along the a-axis direction. Calcifying solution treatments of both demineralized sample types

Tooth loss prevalence among cardiac males and females

International Nuclear Information System (INIS)

Bokhari, S.A.H.; Khan, A.A.; Butt, A.K.

2007-01-01

Objective of study was to observe differences of tooth loss prevalence in males and females with Cardiac diseases Poor oral health, tooth loss and periodontal diseases have been reported to be associated with coronary heart diseases. Studies report gender differences in prevalence of cardiac diseases and tooth loss. This paper presents gender differences of tooth loss in cardiac patients of a cardiac hospital of Lahore, Pakistan. Methodology: Age matched Cardiac males and females attending OPD of the Punjab Institute of Cardiology (PIC), Lahore were included in the study. Personal and health-related information were questioned and noted. Oral examination was performed for recording of missing teeth. 1200 CHD study subjects with age-range of 30 to 80 years were enrolled for study. 1045 age matched, 766 (73.30%) males and 279 (26.70%) females were examined for tooth loss. 852 (81.53%) genders had at least one tooth missing. 599 (78.19) males and 253 (90.68%) females were observed with mean tooth loss of 7.5 (SD 8.720) and 11.15 (SD 10.375)respectively statistical association among them was also significant (P= 0.000) with OR of 2.339. More subjects (76.29%) showed a loss of 1-15 teeth that I was also significant among males and females. Tooth loss was significant in age groups of 41-50 years (P=0.001) and 51-60 years (P=0.000) Gender differences of tooth loss prevalence among CHD Subjects were significant with more risk for males as compared to females. (author)

Functional constraints on tooth morphology in carnivorous mammals

Directory of Open Access Journals (Sweden)

Smits Peter D

2012-08-01

Full Text Available Abstract Background The range of potential morphologies resulting from evolution is limited by complex interacting processes, ranging from development to function. Quantifying these interactions is important for understanding adaptation and convergent evolution. Using three-dimensional reconstructions of carnivoran and dasyuromorph tooth rows, we compared statistical models of the relationship between tooth row shape and the opposing tooth row, a static feature, as well as measures of mandibular motion during chewing (occlusion, which are kinetic features. This is a new approach to quantifying functional integration because we use measures of movement and displacement, such as the amount the mandible translates laterally during occlusion, as opposed to conventional morphological measures, such as mandible length and geometric landmarks. By sampling two distantly related groups of ecologically similar mammals, we study carnivorous mammals in general rather than a specific group of mammals. Results Statistical model comparisons demonstrate that the best performing models always include some measure of mandibular motion, indicating that functional and statistical models of tooth shape as purely a function of the opposing tooth row are too simple and that increased model complexity provides a better understanding of tooth form. The predictors of the best performing models always included the opposing tooth row shape and a relative linear measure of mandibular motion. Conclusions Our results provide quantitative support of long-standing hypotheses of tooth row shape as being influenced by mandibular motion in addition to the opposing tooth row. Additionally, this study illustrates the utility and necessity of including kinetic features in analyses of morphological integration.

Use of ultrasound Doppler to determine tooth vitality in a discolored tooth after traumatic injury: its prospects and limitations

Directory of Open Access Journals (Sweden)

Yong-Wook Cho

2014-02-01

Full Text Available When a tooth shows discoloration and does not respond to the cold test or electric pulp test (EPT after a traumatic injury, its diagnosis can be even more difficult due to the lack of proper diagnostic methods to evaluate its vitality. In these case reports, we hope to demonstrate that ultrasound Doppler might be successfully used to evaluate the vitality of the tooth after trauma, and help reduce unnecessary endodontic treatments. In all three of the present cases, the teeth were discolored after traumatic injuries and showed negative responses to the cold test and EPT. However, they showed distinctive vital reactions in the ultrasound Doppler test during the whole observation period. In the first case, the tooth color returned to normal, and the tooth showed a positive response to the cold test and EPT at 10 wk after the injury. In the second case, the tooth color had returned to its normal shade at 10 wk after the traumatic injury but remained insensitive to the cold test and EPT. In the third case, the discoloration was successfully treated with vital tooth bleaching.

Tooth Retained Implant: No More an Oxymoron

Directory of Open Access Journals (Sweden)

Divya Bhat

2011-03-01

Full Text Available Introduction: Periodontally af-fected teeth are treated in one of the two ways. (1 Tooth retention after periodontal surgery, in which the degree of regeneration achieved is unpredictable. (2 Tooth extrac-tion and implant placement. Implants have an osseointegrated surface which does not provide adequate shock absorption. Regeneration can be achieved by resecting the crown of the affected tooth and submerging the root. This technique has not had a clinical application so far as the tooth becomes difficult to restore. Placing an implant within the root can make the retained root restorable. At the same time, as the implant is placed within the root surface it achieves a periodontal integration which dampens occlusal forces better than osseointegration. Therefore, such a “tooth retained implant” may serve as an additional treatment option with significant benefits over tooth retention and implant placement alone. The hypothesis: Implants placed within retained roots have shown cementum deposition and attachment of periodontal ligament fibers over their surface. This periodontal attachment may be able to dam-pen forces better than in an osseointegrated implant. Moreover, since an implant is being placed, the crown of the tooth can be resected and submerged. This prevents epithelial migration, allows for the periodontal ligament cells to populate the wound and favors regeneration.Evaluation of the hypothesis: The technique of placing implants within cavities prepared in the root and then submerging them are simple for any practitioner placing implants routinely.

Evolving magma storage conditions beneath Mount St. Helens inferred from chemical variations in melt inclusions from the 1980-1986 and current (2004-2006) eruptions: Chapter 33 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

Science.gov (United States)

Blundy, Jon; Cashman, Katharine V.; Berlo, Kim; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

Major element, trace element, and volatile concentrations in 187 glassy melt inclusions and 25 groundmass glasses from the 1980-86 eruption of Mount St. Helens are presented, together with 103 analyses of touching FE-Ti oxide pairs from the same samples. These data are used to evaluate the temporal evolution of the magmatic plumbing system beneath the volcano during 1980-86 and so provide a framework in which to interpret analyses of melt inclusions from the current (2004-2006) eruption. Major and trace element concentrations of all melt inclusions lie at the high SiO2 end of the data array defined by eruptive products of the late Quaternary age from Mount St. Helens. For several major and trace elements, the glasses define a trend that is oblique to the whole-rock trend, indicating that different mineral assemblages were responsible for the two trends. The whole-rock trend can be ascribed to differentiation of hydrous basaltic parents in a deep-seated magma reservoir, probably at depths great enough to stabilize garnet. In contrast, the glass trends were generated by closed-system crystallization of the phenocryst and microlite mineral assemblages at low pressures. The dissolved H2O content of the melt inclusions from 1980-86, as measured by the ion microprobe, ranges from 0 to 6.7 wt. percent, with the highest values obtained from the plinian phase of May 18, 1980. Water contents decrease with increasing SiO2, consistent with decompression-driven crystallization. Preliminary data for dissolved CO2 in melt inclusions from the May 18 plinian phase from August 7, 1980, indicate that XH2O in a vapor phase was approximately constant at 0.80, irrespective of H2O content, suggestive of closed-system degassing with a high bubble fraction or gas streaming through the subvolcanic system. Temperature and f

Phreatic eruption clouds: the activity of La Soufriere de Guadeloupe, F. W. I. , August-October, 1976

Energy Technology Data Exchange (ETDEWEB)

Heiken, G.; Crowe, B.; McGetchin, T.; West, F.; Eichelberger, J.; Bartram, D.; Peterson, R.; Wohletz, K.

1980-01-01

From August to October, 1976, La Soufriere de Guadeloupe was observed, and recorded with an automated sequence camera and numerous handheld cameras. During the period of observation, the nature of volcanic activity ranged from mild steam emission to moderately energetic phraetic eruptions. The concurrent growth of clouds from separate vents (summit and flank) implies a common source. Simultaneous eruption of tephra-free and tephra-laden clouds from the same vent is puzzling and implies: (i) lateral changes in the degree of alteration of dome rocks along the elongate vent, hence erodability of the dome lavas, or (ii) differences in the gas velocities. These mixed clouds moved westward, downwind and downslope as a density current, with an approximate velocity of 10 to 25 m/sec. Upon reaching the sea the clouds continued to move forward, but at a decreased velocity, and spread laterally, having left behind the restrictions of valley walls. A thin gray veneer of moist tephra, ranging from several cm thick near the dome to less than 1 mm thick several km downwind, was deposited along a narrow corridor southwest of the summit. Tephra from the phreatic eruptions consisted mostly of hydrothermally altered lithic, mineral, and glass fragments derived from dome lavas; no fresh (juvenile) pyroclasts were present in the tephra.

Autogenous Transplantation for Replacing a Hopeless Tooth.

Science.gov (United States)

Zakershahrak, Mehrsa; Moshari, Amirabbas; Vatanpour, Mehdi; Khalilak, Zohreh; Jalali Ara, Afsoon

2017-01-01

Autogenous tooth transplantation (ATT) is a simple and reasonable choice for replacing the missing teeth when a proper donor tooth is available. This report presents a case of successful ATT of a maxillary right third molar for replacement of mandibular right second molar with a concomitant endodontic-periodontal disease. The mandibular second molar was believed to be hopeless due to a severe damage to coronal tooth structure, inappropriate root canal treatment and apical radiolucency. After extraction of mandibular second molar and maxillary third molar (the donor), the tooth was re-implanted into the extracted socket of second molar site. Root canal therapy was then performed. After 3 years, clinical and radiographic examinations revealed satisfying results, with no signs and symptoms. The patient is asymptomatic and the transplanted tooth is still functional with no signs of marginal periodontal pathosis. Radiographies showed bone regeneration in the site of previous extensive periapical lesion, normal periodontal ligament with no signs of root resorption.

Bmp 2 and bmp 7 induce odonto- and osteogenesis of human tooth germ stem cells.

Science.gov (United States)

Taşlı, P Neslihan; Aydın, Safa; Yalvaç, Mehmet Emir; Sahin, Fikrettin

2014-03-01

Bone morphogenetic proteins (BMPs) initiate, promote, and maintain odontogenesis and osteogenesis. In this study, we studied the effect of bone morphogenic protein 2 (BMP 2) and bone morphogenic protein 7 (BMP 7) as differentiation inducers in tooth and bone regeneration. We compared the effect of BMP 2 and BMP 7 on odontogenic and osteogenic differentiation of human tooth germ stem cells (hTGSCs). Third molar-derived hTGSCs were characterized with mesenchymal stem cell surface markers by flow cytometry. BMP 2 and BMP 7 were transfected into hTGSCs and the cells were seeded onto six-well plates. One day after the transfection, hTGSCs were treated with odontogenic and osteogenic mediums for 14 days. For confirmation of odontogenic and osteogenic differentiation, mRNA levels of BMP2, BMP 7, collagen type 1 (COL1A), osteocalsin (OCN), and dentin sialophosphoprotein (DSPP) genes were measured by quantitative real-time PCR. In addition to this, immunocytochemistry was performed by odontogenic and osteogenic antibodies and mineralization obtained by von Kossa staining. Our results showed that the BMP 2 and BMP 7 both promoted odontogenic and osteogenic differentiation of hTGSCs. Data indicated that BMP 2 treatment and BMP 7 treatment induce odontogenic differentiation without affecting each other, whereas they induce osteogenic differentiation by triggering expression of each other. These findings provide a feasible tool for tooth and bone tissue engineering.

An Integrative Approach for Defining Plinian and Sub-Plinian Eruptive Scenarios at Andesitic Volcanoes: Event-Lithostratigraphy, Eruptive Parameters and Pyroclast Textural Variations of the Largest Late-Holocene Eruptions of Mt. Taranaki, New Zealand.

Science.gov (United States)

Torres-Orozco, R.; Cronin, S. J.; Damaschke, M.; Kosik, S.; Pardo, N.

2016-12-01

Three eruptive scenarios were determined based on the event-lithostratigraphic reconstruction of the largest late-Holocene eruptions of the andesitic Mt. Taranaki, New Zealand: a) sustained dome-effusion followed by sudden stepwise collapse and unroofing of gas-rich magma; b) repeated plug and burst events generated by transient open-/closed-vent conditions; and c) open-vent conditions of more mafic magmas erupting from a satellite vent. Pyroclastic density currents (PDCs) are the most frequent outcome in every scenario. They can be produced in any/every eruption phase by formation and either repetitive-partial or total gravity-driven collapse of lava domes in the summit crater (block-and-ash flows), frequently followed by sudden magma decompression and violent, highly unsteady to quasi-steady lateral expansion (blast-like PDCs); by collapse or single-pulse fall-back of unsteady eruption columns (pyroclastic flow- and surge-type currents); or during highly unsteady and explosive hydromagmatic phases (wet surges). Fall deposits are produced during the climatic phase of each eruptive scenario by the emplacement of (i) high, sustained and steady, (ii) sustained and height-oscillating, (iii) quasi-steady and pulsating, or (iv) unsteady and totally collapsing eruption columns. Volumes, column heights and mass- and volume-eruption rates indicate that these scenarios correspond to VEI 4-5 plinian and sub-plinian multi-phase and style-shifting episodes, similar or larger than the most recent 1655 AD activity, and comparable to plinian eruptions of e.g. Apoyeque, Colima, Merapi and Tarawera volcanoes. Whole-rock chemistry, textural reconstructions and density-porosity determinations suggest that the different eruptive scenarios are mainly driven by variations in the density structure of magma in the upper conduit. Assuming a simple single conduit model, the style transitions can be explained by differing proportions of alternating gas-poor/degassed and gas-rich magma.

Failed magmatic eruptions: Late-stage cessation of magma ascent

Science.gov (United States)

Moran, S.C.; Newhall, C.; Roman, D.C.

2011-01-01

When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" stage, i. e., when magma gets close to, but does not reach, the surface. Competing factors act to promote or hinder the eventual eruption of a magma intrusion. Fresh intrusion from depth, high magma gas content, rapid ascent rates that leave little time for enroute degassing, opening of pathways, and sudden decompression near the surface all act to promote eruption, whereas decreased magma supply from depth, slow ascent, significant enroute degassing and associated increases in viscosity, and impingement on structural barriers all act to hinder eruption. All of these factors interact in complex ways with variable results, but often cause magma to stall at some depth before reaching the surface. Although certain precursory phenomena, such as rapidly escalating seismic swarms or rates of degassing or deformation, are good indicators that an eruption is likely, such phenomena have also been observed in association with intrusions that have ultimately failed to erupt. A perpetual difficulty with quantifying the probability of eruption is a lack of data, particularly on instances of failed eruptions. This difficulty is being addressed in part through the WOVOdat database. Papers in this volume will be an additional resource for scientists grappling with the issue of whether or not an episode of unrest will lead to a magmatic eruption.

High-resolution Observations of Sympathetic Filament Eruptions by NVST

Energy Technology Data Exchange (ETDEWEB)

Li, Shangwei; Su, Yingna; Zhou, Tuanhui; Ji, Haisheng [Key Laboratory for Dark Matter and Space Science, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Van Ballegooijen, Adriaan [5001 Riverwood Avenue, Sarasota, FL 34231 (United States); Sun, Xudong, E-mail: ynsu@pmo.ac.cn [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2017-07-20

We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts first, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions failed, since the filaments first rise up, then flow toward the south and merge into the southern large quiescent filament. We also observe repeated activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.

Pre-eruptive conditions of the ~31 ka rhyolitic magma of Tlaloc volcano, Sierra Nevada Volcanic Range, Central Mexico

Science.gov (United States)

Macias, J.; Arce, J.; Rueda, H.; Gardner, J.

2008-12-01

Tlaloc volcano is located at the northern tip of the Sierra Nevada Volcanic Range in Central Mexico. This Pleistocene to Recent volcanic range consists from north to south of Tlaloc-Telapón-Teyotl-Iztaccíhuatl-and- Popocatépetl volcanoes. While andesitic to barely dacitic volcanism dominates the southern part of the range (i.e. Popocatépetl and Iztaccíhuatl); dacitic and rare rhyolithic volcanism (i.e. Telapón, Tlaloc) dominates the northern end. The known locus of rhyolitic magmatism took place at Tlaloc volcano with a Plinian-Subplinian eruption that occurred 31 ka ago. The eruption emplaced the so-called multilayered fallout and pumiceous pyroclastic flows (~2 km3 DRE). The deposit consists of 95% vol. of juvenile particles (pumice + crystals) and minor altered lithics 5% vol. The mineral association of the pumice fragments (74-76 % wt. SiO2) consists of quartz + plagioclase + sanidine + biotite and rare oxides set in a glassy groundmass with voids. Melt inclusions in quartz phenocrysts suggest that prior to the eruption the rhyolitic contain ~7% of H2O and Nevado de Toluca volcano (~6 km) some 50 km to the southwest.

21 CFR 872.3580 - Preformed gold denture tooth.

Science.gov (United States)

2010-04-01

... tooth in a fixed or removable partial denture. (b) Classification. Class I (general controls). The... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Preformed gold denture tooth. 872.3580 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3580 Preformed gold denture tooth. (a...

Mineral mining machines

Energy Technology Data Exchange (ETDEWEB)

Mc Gaw, B H

1984-01-01

A machine for mining minerals is patented. It is a cutter loader with a drum actuating element of the worm type equipped with a multitude of cutting teeth reinforced with tungsten carbide. A feature of the patented machine is that all of the cutting teeth and holders on the drum have the identical design. This is achieved through selecting a slant angle for the cutting teeth which is the mean between the slant angle of the conventional radial teeth and the slant angle of the advance teeth. This, in turn, is provided thanks to the corresponding slant of the holders relative to the drum and (or) the slant of the cutting part of the teeth relative to their stems. Thus, the advance teeth projecting beyond the surface of the drum on the face side and providing upper and lateral clearances have the same angle of attack as the radial teeth, that is, from 20 to 35 degrees. A series of modifications of the cutting teeth is patented. One of the designs allows the cutting tooth to occupy a varying position relative to the drum, from the conventional vertical to an inverted, axially projecting position. In the last case the tooth in the extraction process provides the upper and lateral clearances for the drum on the face side. Among the different modifications of the cutting teeth, a design is proposed which provides for the presence of a stem which is shaped like a truncated cone. This particular stem is designed for use jointly with a wedge which unfastens the teeth and is placed in a holder. The latter is completed in a transverse slot thanks to which the rear end of the stem is compressed, which simplifies replacement of a tooth. Channels are provided in the patented machine for feeding water to the worm spiral, the holders and the cutting teeth themselves in order to deal with dust.

Eruptions at Lone Star Geyser, Yellowstone National Park, USA, part 1: energetics and eruption dynamics

Science.gov (United States)

Karlstrom, Leif; Hurwitz, Shaul; Sohn, Robert; Vandemeulebrouck, Jean; Murphy, Fred; Rudolph, Maxwell L.; Johnston, Malcolm J.S.; Manga, Michael; McCleskey, R. Blaine

2013-01-01

Geysers provide a natural laboratory to study multiphase eruptive processes. We present results from a four–day experiment at Lone Star Geyser in Yellowstone National Park, USA. We simultaneously measured water discharge, acoustic emissions, infraredintensity, and visible and infrared video to quantify the energetics and dynamics of eruptions, occurring approximately every three hours. We define four phases in the eruption cycle: 1) a 28 ± 3 minute phase with liquid and steam fountaining, with maximum jet velocities of 16–28 m s− 1, steam mass fraction of less than ∼ 0.01. Intermittently choked flow and flow oscillations with periods increasing from 20 to 40 s are coincident with a decrease in jet velocity and an increase of steam fraction; 2) a 26 ± 8 minute post–eruption relaxation phase with no discharge from the vent, infrared (IR) and acoustic power oscillations gliding between 30 and 40 s; 3) a 59 ± 13 minute recharge period during which the geyser is quiescent and progressively refills, and 4) a 69 ± 14 minute pre–play period characterized by a series of 5–10 minute–long pulses of steam, small volumes of liquid water discharge and 50–70 s flow oscillations. The erupted waters ascend froma 160 − 170° C reservoir and the volume discharged during the entire eruptive cycle is 20.8 ± 4.1 m3. Assuming isentropic expansion, we calculate a heat output from the geyser of 1.4–1.5 MW, which is < 0.1% of the total heat output from Yellowstone Caldera.

Elastic energy release in great earthquakes and eruptions

Directory of Open Access Journals (Sweden)

Agust eGudmundsson

2014-05-01

Full Text Available The sizes of earthquakes are measured using well-defined, measurable quantities such as seismic moment and released (transformed elastic energy. No similar measures exist for the sizes of volcanic eruptions, making it difficult to compare the energies released in earthquakes and eruptions. Here I provide a new measure of the elastic energy (the potential mechanical energy associated with magma chamber rupture and contraction (shrinkage during an eruption. For earthquakes and eruptions, elastic energy derives from two sources: (1 the strain energy stored in the volcano/fault zone before rupture, and (2 the external applied load (force, pressure, stress, displacement on the volcano/fault zone. From thermodynamic considerations it follows that the elastic energy released or transformed (dU during an eruption is directly proportional to the excess pressure (pe in the magma chamber at the time of rupture multiplied by the volume decrease (-dVc of the chamber, so that . This formula can be used as a basis for a new eruption magnitude scale, based on elastic energy released, which can be related to the moment-magnitude scale for earthquakes. For very large eruptions (>100 km3, the volume of the feeder-dike is negligible, so that the decrease in chamber volume during an eruption corresponds roughly to the associated volume of erupted materials , so that the elastic energy is . Using a typical excess pressures of 5 MPa, it is shown that the largest known eruptions on Earth, such as the explosive La Garita Caldera eruption (27-28 million years ago and largest single (effusive Colombia River basalt lava flows (15-16 million years ago, both of which have estimated volumes of about 5000 km3, released elastic energy of the order of 10EJ. For comparison, the seismic moment of the largest earthquake ever recorded, the M9.5 1960 Chile earthquake, is estimated at 100 ZJ and the associated elastic energy release at 10EJ.

Phreatomagmatic eruptive and depositional processes during the 1949 eruption on La Palma (Canary Islands)

Science.gov (United States)

White, James D. L.; Schmincke, Hans-Ulrich

1999-12-01

In 1949, a 5-week-long magmatic and phreatomagmatic eruption took place along the active volcanic ridge of La Palma (Canary Islands). Two vents, Duraznero and Hoyo Negro, produced significant pyroclastic deposits. The eruption began from Duraznero vent, which produced a series of deposits with an upward decrease in accidental fragments and increase in fluidal ash and spatter, together inferred to indicate decreasing phreatomagmatic interaction. Hoyo Negro erupted over a 2-week period, producing a variety of pyroclastic density currents and ballistic blocks and bombs. Hoyo Negro erupted within and modified an older crater having high walls on the northern to southeastern edges. Southwestern to western margins of the crater lay 50 to 100 m lower. Strongly contrasting deposits in the different sectors (N-SE vs. SW-W) were formed as a result of interaction between topography, weak eruptive columns and stratified pyroclastic density currents. Tephra ring deposits are thicker and coarser-grained than upper rim deposits formed along the higher edges of the crater, and beyond the crater margin, valley-confined deposits are thicker than more thinly bedded mantling deposits on higher topography. These differences indicate that the impact zone for the bulk of the collapsing, tephra-laden column lay within the crater and that the high crater walls inhibited escape of pyroclastic density currents to the north and east. The impact zone lay outside the low SW-W rims, however, thus allowing stratified pyroclastic density currents to move freely away from the crater in those directions, depositing thin sections (<30 cm) of well-bedded ash (mantling deposits) on ridges and thicker sections (1-3 m) of structureless ash beds in valleys and small basins. Such segregation of dense pyroclastic currents from more dilute ones at the crater wall is likely to be common for small eruptions from pre-existing craters and is an important factor to be taken into account in volcanic hazards

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples.

Science.gov (United States)

Damby, David E; Horwell, Claire J; Larsen, Gudrun; Thordarson, Thorvaldur; Tomatis, Maura; Fubini, Bice; Donaldson, Ken

2017-09-11

The eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland's volcanoes to Icelandic and Northern European populations. A physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network. Icelandic ash can be of a respirable size (up to 11.3 vol.% fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m 2  g -1 , which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO • ), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after 'refreshing' sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m -2 , with mafic samples releasing more iron than silicic samples. All samples were non-reactive in a test of red blood cell-membrane damage. The primary particle-specific concern is the potential for future eruptions of Iceland's volcanoes to generate fine, respirable material and, thus, to

Diverse Eruptive Activity Revealed by Acoustic and Electromagnetic Observations of the 14 July 2013 Intense Vulcanian Eruption of Tungurahua Volcano, Ecuador

Science.gov (United States)

Anderson, J. F.; Johnson, J. B.; Steele, A. L.; Ruiz, M. C.; Brand, B. D.

2018-04-01

During the powerful July 2013 eruption of Tungurahua volcano, Ecuador, we recorded exceptionally high amplitude, long-period infrasound (1,600-Pa peak-to-peak amplitude, 5.5-s period) on sensors within 2 km of the vent alongside electromagnetic signals from volcanic lightning serendipitously captured as interference. This explosion was one of Tungurahua's most powerful vulcanian eruptions since recent activity began in 1999, and its acoustic wave is among the most powerful volcanic infrasound ever recorded anywhere. We use these data to quantify erupted volume from the main explosion and to classify postexplosive degassing into distinct emission styles. Additionally, we demonstrate a highly effective method of recording lightning-related electromagnetic signals alongside infrasound. Detailed chronologies of powerful vulcanian eruptions are rare; this study demonstrates that diverse eruptive processes can occur in such eruptions and that near-vent infrasound and electromagnetic data can elucidate them.

21 CFR 872.5525 - Preformed tooth positioner.

Science.gov (United States)

2010-04-01

...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5525 Preformed tooth positioner. (a) Identification. A preformed tooth positioner is a plastic device that is an impression of a perfected bite...

Remineralising efficacy of tooth mousse plus (ACP CCPF) on radiated tooth

International Nuclear Information System (INIS)

Priya; Hegde, Mithra N.; Hegde, Nidarsh D.; Suchetha Kumari, N.; Sanjeev, Ganesh

2016-01-01

Dental complication is the common problem faced all over the world. Subjects with poor oral hygiene and patients undergoing radiotherapy for oral cancers are developing signs of decalcification of enamel, lesions and Caries. A well designed treatment is necessary to safeguard the tooth enamel surface before and after radiation, only then the caries on the enamel surface can be arrested by re-hardening it and ultimately converting them to the normal healthy condition. To determine the Annealing effect of radiated tooth by testing maximum micro hardness of the teeth before and after 30 days of radiation by the application of Remineralising agents. In our study, we collected 30 intact caries free human molar teeth and were sectioned mesio-distally

The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

Science.gov (United States)

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia

2015-08-01

The purpose of this in vitro study was to evaluate the influence of a novel in-office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel. Forty-eight enamel specimens were prepared from bovine canines and divided into four groups: Group 1 specimens (control) received no whitening treatment; Group 2 received whitening treatment with an at-home whitening agent (22% carbamide peroxide) for 7 days; Group 3 received whitening treatment with a novel in-office whitening agent (35% H(2)O(2)); Group 4 received the same in-office whitening therapy with Group 3 using Er,Cr:YSGG laser in order to accelerate the whitening procedure. The specimens were stored for 10 days after the whitening treatment in artificial saliva. Vickers hardness was determined using a microhardness tester and surface roughness was evaluated using a VSI microscope. Three specimens of each experimental group were examined under SEM and the mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post-hoc test, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The surface microhardness of the enamel was reduced after the in-office whitening treatments (Pwhitening treatment (P> 0.05). Moreover, the surface roughness was not significantly changed after tooth whitening. EDS analysis did not show alterations in the enamel mineral composition, while SEM observations indicated changes in the surface morphology, especially after in-office tooth whitening (Pwhitening treatment with Er,Cr:YSGG laser did not affect the alterations in enamel surface compared with the conventional in-office whitening technique. © 2015 Wiley Periodicals, Inc.

Parameters affecting tooth loss during periodontal maintenance in a Greek population.

Science.gov (United States)

Tsami, Alexandra; Pepelassi, Eudoxie; Kodovazenitis, George; Komboli, Mado

2009-09-01

Investigators have evaluated predictive parameters of tooth loss during the maintenance phase (MP). The authors conducted a retrospective study to evaluate the rate of tooth loss and to explore the parameters that affect tooth loss during MP in a Greek population. A periodontist administered periodontal treatment and maintenance care to 280 participants with severe periodontitis for a mean period +/- standard deviation of 10.84 +/- 2.13 years. The periodontist recorded the following parameters for each participant: oral hygiene index level, simplified gingival index level, clinical attachment level, probing depth measurements, initial tooth prognosis, smoking status, tooth loss during active periodontal treatment and MP, and compliance with suggested maintenance visits. The authors found that total tooth loss during active treatment (n = 1,427) was greater than during MP (n = 918) and was associated with the initial tooth prognosis, tooth type group, participants' compliance with suggested maintenance visits, smoking status and acceptability of the quality of tooth restorations. Most of the teeth extracted during maintenance had an initial guarded prognosis (n = 612). Participants whose compliance was erratic had a greater risk of undergoing tooth extraction than did participants whose compliance was complete. Participants' initial tooth prognosis, tooth type, compliance with suggested maintenance visits and smoking status affected tooth loss during MP. Initial guarded prognosis and erratic compliance increased the risk of undergoing tooth extraction during maintenance. Determining predictive parameters for disease progression and tooth loss provides critical information to clinicians so that they can develop and implement rational treatment planning.

Stratospheric sulfate from the Gareloi eruption, 1980: Contribution to the ''ambient'' aerosol by a poorly documented volcanic eruption

International Nuclear Information System (INIS)

Sedlacek, W.A.; Mroz, E.J.; Heiken, G.

1981-01-01

While sampling stratospheric aerosols during July--August 1980 a plume of ''fresh'' volcanic debris was observed in the Northern hemisphere. The origin of this material seems to be a poorly documented explosive eruption of Gareloi valcano in the Aleutian Islands. The debris was sampled at an altitude of 19.2 km: almost twice the height of observed eruption clouds. Such remote, unobserved or poorly documented eruptions may be a source that helps maintain the ''ambient'' stratospheric aerosol background

A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

Science.gov (United States)

Sarkar, Ranadeep; Srivastava, Nandita

2018-02-01

We investigate the morphological and magnetic characteristics of solar active region (AR) NOAA 12192. AR 12192 was the largest region of Solar Cycle 24; it underwent noticeable growth and produced 6 X-class flares, 22 M-class flares, and 53 C-class flares in the course of its disc passage. However, the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. In this work, we carry out a comparative study between the eruptive and non-eruptive flares produced by AR 12192. We find that the magnitude of abrupt and permanent changes in the horizontal magnetic field and Lorentz force are significantly smaller in the case of the confined flares compared to the eruptive one. We present the areal evolution of AR 12192 during its disc passage. We find the flare-related morphological changes to be weaker during the confined flares, whereas the eruptive flare exhibits a rapid and permanent disappearance of penumbral area away from the magnetic neutral line after the flare. Furthermore, from the extrapolated non-linear force-free magnetic field, we examine the overlying coronal magnetic environment over the eruptive and non-eruptive zones of the AR. We find that the critical decay index for the onset of torus instability was achieved at a lower height over the eruptive flaring region, than for the non-eruptive core area. These results suggest that the decay rate of the gradient of overlying magnetic-field strength may play a decisive role to determine the CME productivity of the AR. In addition, the magnitude of changes in the flare-related magnetic characteristics are found to be well correlated with the nature of solar eruptions.

Global time-size distribution of volcanic eruptions on Earth.

Science.gov (United States)

Papale, Paolo

2018-05-01

Volcanic eruptions differ enormously in their size and impacts, ranging from quiet lava flow effusions along the volcano flanks to colossal events with the potential to affect our entire civilization. Knowledge of the time and size distribution of volcanic eruptions is of obvious relevance for understanding the dynamics and behavior of the Earth system, as well as for defining global volcanic risk. From the analysis of recent global databases of volcanic eruptions extending back to more than 2 million years, I show here that the return times of eruptions with similar magnitude follow an exponential distribution. The associated relative frequency of eruptions with different magnitude displays a power law, scale-invariant distribution over at least six orders of magnitude. These results suggest that similar mechanisms subtend to explosive eruptions from small to colossal, raising concerns on the theoretical possibility to predict the magnitude and impact of impending volcanic eruptions.

Concentrations of {sup 90}Sr in the tooth tissues 60 years after intake: results of TL measurements and applications for Techa River dosimetry

Energy Technology Data Exchange (ETDEWEB)

Shishkina, E.A.; Tolstykh, E.I.; Volchkova, A.Yu.; Degteva, M.O. [Urals Research Center for Radiation Medicine, Chelyabinsk (Russian Federation); Verdi, E. [German Research Centre for Environmental Health, Helmholtz Zentrum Muenchen, Neuherberg (Germany); Veronese, I. [Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); INFN, Rome (Italy); El-Faramawy, N.A. [German Research Centre for Environmental Health, Helmholtz Zentrum Muenchen, Neuherberg (Germany); Ain Shams University, Department of Physics, Faculty of Science, Cairo (Egypt); Goeksu, H.Y. [German Research Centre for Environmental Health, Helmholtz Zentrum Muenchen, Neuherberg (Germany); Adiyaman University, Department of Physics, Faculty of Science and Art, Adiyaman (Turkey)

2014-03-15

This article focuses on the study of {sup 90}Sr in the tooth tissues of Techa riverside residents 60 years after intake. The Techa River was contaminated by radioactive wastes in the 1950s. Contamination of the river system, including water, bottom sediment, floodplain soil, and grass, depended on the distance from the source of releases. Therefore, the average {sup 90}Sr intake was different in different settlements located downstream the river. An additional factor influencing {sup 90}Sr accumulation in the teeth is the rate of tissue mineralization at the time of intake which depended on the donor's age at the time of releases. Measurements of {sup 90}Sr concentration in various dental tissues (enamel, crown, and root dentin) of 166 teeth were performed about 60 years after the main intake using the method of thermoluminescence passive beta detection. The paper presents the current levels of tooth tissue contamination, and the tooth-to-tooth variability of {sup 90}Sr concentration in tooth tissues was assessed for the tissues which were matured at the time of massive liquid radioactive waste releases into the Techa River. A model describing the expected levels of {sup 90}Sr in matured dental tissues depending on age and intake has been elaborated for the population under study. The results obtained will be used for calculation of internal dose in enamel and for interpretation of tooth doses measured by means of the electron paramagnetic resonance method, among the population of the Techa River region. (orig.)

Severe hypertriglyceridemia presenting as eruptive xanthomatosis

Directory of Open Access Journals (Sweden)

Sameera S Vangara

2018-01-01

Full Text Available Eruptive xanthomatosis is described as the sudden eruption of erythematous yellow papules in the presence of hypertriglyceridemia, often associated with serum triglyceride levels above 2000 mg/dl. Severe hypertriglyceridemia can be caused by primary genetic mutations, secondary chronic diseases, or a combination of both. Uncontrolled diabetes mellitus is a known risk factor. It is imperative for physicians to be aware of eruptive xanthomatosis as a warning sign for severe hypertriglyceridemia due to the underlying risk for the potentially fatal complication of acute pancreatitis. Herein, we discuss a case of a 52-year-old man with uncontrolled diabetes mellitus who presented with eruptive xanthomata and a triglyceride level of 7157 mg/dl, the highest recorded value in the absence of acute pancreatitis, with a remarkable response to drug therapy. A review of the literature is included to discuss the clinical relevance and appropriate treatment of this disease entity.

Variables affecting orthodontic tooth movement with clear aligners.

Science.gov (United States)

Chisari, Justin R; McGorray, Susan P; Nair, Madhu; Wheeler, Timothy T

2014-04-01

In this study, we examined the impacts of age, sex, root length, bone levels, and bone quality on orthodontic tooth movement. Clear aligners were programmed to move 1 central incisor 1 mm over the course of 8 weeks. Thirty subjects, ages 19 to 64, were enrolled, and measurements were made on digital models (percentage of tooth movement goal achieved). Morphometric features and bone quality were assessed with cone-beam computed tomography. Data from this study were combined with data from 2 similar studies to increase the power for some analyses. The mean percentage of tooth movement goal achieved was 57% overall. Linear regression modeling indicated a cubic relationship between age and tooth movement, with a decreasing rate of movement from ages 18 to 35 years, a slightly increasing rate from ages 35 to 50, and a decreasing rate from ages 50 to 70. The final decreasing trend was not apparent for women. As would be expected, the correlation was significant between the percentage of the goal achieved and the cone-beam computed tomography superimposed linear measures of tooth movement. A significant negative correlation was found between tooth movement and the measurement apex to the center of rotation, but bone quality, as measured by fractal dimension, was not correlated with movement. The relationship between age and tooth movement is complex and might differ for male and female patients. Limited correlations with cone-beam computed tomography morphology and rate of tooth movement were detected. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

The Eruption Forecasting Information System (EFIS) database project

Science.gov (United States)

Ogburn, Sarah; Harpel, Chris; Pesicek, Jeremy; Wellik, Jay; Pallister, John; Wright, Heather

2016-04-01

The Eruption Forecasting Information System (EFIS) project is a new initiative of the U.S. Geological Survey-USAID Volcano Disaster Assistance Program (VDAP) with the goal of enhancing VDAP's ability to forecast the outcome of volcanic unrest. The EFIS project seeks to: (1) Move away from relying on the collective memory to probability estimation using databases (2) Create databases useful for pattern recognition and for answering common VDAP questions; e.g. how commonly does unrest lead to eruption? how commonly do phreatic eruptions portend magmatic eruptions and what is the range of antecedence times? (3) Create generic probabilistic event trees using global data for different volcano 'types' (4) Create background, volcano-specific, probabilistic event trees for frequently active or particularly hazardous volcanoes in advance of a crisis (5) Quantify and communicate uncertainty in probabilities A major component of the project is the global EFIS relational database, which contains multiple modules designed to aid in the construction of probabilistic event trees and to answer common questions that arise during volcanic crises. The primary module contains chronologies of volcanic unrest, including the timing of phreatic eruptions, column heights, eruptive products, etc. and will be initially populated using chronicles of eruptive activity from Alaskan volcanic eruptions in the GeoDIVA database (Cameron et al. 2013). This database module allows us to query across other global databases such as the WOVOdat database of monitoring data and the Smithsonian Institution's Global Volcanism Program (GVP) database of eruptive histories and volcano information. The EFIS database is in the early stages of development and population; thus, this contribution also serves as a request for feedback from the community.

Tooth resorption in cats: contribution of vitamin D and inflammation

NARCIS (Netherlands)

Vrieling, H.E.

2010-01-01

Tooth resorption in cats Tooth resorption affecting several teeth is a painful disease with a prevalence of up to 75% in household cats and is often accompanied by periodontitis. Tooth resorption is caused by an increased number and activity of tooth-resorbing odontoclasts, cells that share

Tooth fractures in canine clinical practice

International Nuclear Information System (INIS)

Capik, I.; Ledecky, V.; Sevcik, A.

2001-01-01

Tooth fractures constitute a considerable fraction of all tooth diseases. Out of the 5,370 dogs treated during four years, 492 were presented with dental problems and 28.3 % of the latter were treated for tooth fractures. Canines were the most frequently affected teeth (38.8 %), followed by premolars (33.1 %), incisors (25.9 %), and molars (2.2 %), 55.4 % of the patients with canine and incisor fractures being large breed dogs. Fractures of premolars (mostly of 108, 208) were divided evenly irrespective of breed or body size. Nonsurgical endodontic treatment yielded good therapeutic results in most cases, but repeated treatment was necessary in some patients

Small-scale eruptive filaments on the quiet sun

International Nuclear Information System (INIS)

Hermans, L.M.; Martin, S.F.

1986-01-01

A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments

Permanent molars: Delayed development and eruption

Directory of Open Access Journals (Sweden)

Arathi R

2006-05-01

Full Text Available Delayed development and eruption of all the permanent molars is a rare phenomenon, which can cause disturbance in the developing occlusion. The eruption of permanent first and second molars is very important for the coordination of facial growth and for providing sufficient occlusal support for undisturbed mastication. In the case described, the first permanent molars were delayed in their development and were seen erupting at the age of nine and a half years. Severe disparity between the left and the right side of the dentition with respect to the rate of development of molars were also present.

Efektivitas Desensitizing Agent dengan dan tanpa Fluor pada Metode in Office Bleaching terhadap Kandungan Mineral Gigi (Kajian In Vitro

Directory of Open Access Journals (Sweden)

Yulita Kristanti

2015-12-01

Full Text Available In office bleaching menggunakan hidrogen peroksida 40% sering memberikan efek samping berupa linu baik selama maupun setelah perawatan tersebut dilakukan. Penelitian ini dilakukan dengan tujuan untuk mengetahui pengaruh waktu aplikasi dan kandungan fluor desensitizing agent pada metode in office bleaching terhadap kandungan mineral gigi. Delapan gigi masing-masing dipotong menjadi 4 bagian, 6 potong digunakan untuk pemeriksaan XRD awal. Gigi dikeringkan dalam oven suhu 50° selama 30 menit diserbuk, diambil 1 mg untuk diperiksa kandungan mineralnya dengan goniometer. Dua puluh empat potong yang lain dibagi dalam 4 kelompok perlakuan. Kelompok I: gigi diaplikasi bahan bleaching 0,5-1 mm hidrogen peroksida 40% selama 1 jam, dicuci, dikeringkan, diikuti aplikasi 0,1 ml desensitizing agent tanpa fluor (CPP-ACP selama 30 menit, dicuci, dikeringkan. Kelompok II : gigi diaplikasi CPP-ACP 30 menit, dicuci, dikeringkan, dibleaching menggunakan hidrogen peroksida 40% selama 1 jam. Selanjutnya gigi diaplikasi CPP-ACP 30 menit lagi, dicuci, dikeringkan. Kelompok III gigi dibleaching menggunakan hidrogen peroksida 40% selama 1 jam, dicuci, dikeringkan, diikuti aplikasi desensitizing agent yang mengandung fluor (CPP-ACFP selama 30 menit, dicuci, dikeringkan. Kelompok IV: gigi diaplikasi CPP-ACFP 30 menit, dicuci, dikeringkan, dibleaching menggunakan hidrogen peroksida 40% selama 1 jam. Selanjutnya gigi diaplikasi CPP-ACFP selama 30 menit, dicuci dikeringkan. Sesudah perlakuan, semua gigi dilakukan pemeriksaan kandungan mineral gigi dengan prosedur yang sama. Uji Mann Whitney menunjukkan penurunan mineral paling sedikit terjadi pada kelompok IV (4500. Desensitizing agent mengandung F sebelum dan sesudah perlakuan in office bleaching menunjukkan penurunan mineral paling kecil.   The Effectiveness of Desensitizing Agent with and without Fluorine in Office Bleaching Method to Tooth Mineral content. Tooth sensitivity arises during or after an in

The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption

Science.gov (United States)

Klügel, Andreas; Hoernle, Kaj A.; Schmincke, Hans-Ulrich; White, James D. L.

2000-03-01

The 1949 rift zone eruption along the Cumbre Vieja ridge on La Palma involved three eruptive centers, 3 km spaced apart, and was chemically and mineralogically zoned. Duraznero crater erupted tephrite for 14 days and shut down upon the opening of Llano del Banco, a fissure that issued first tephrite and, after 3 days, basanite. Hoyo Negro crater opened 4 days later and erupted basanite, tephrite, and phonotephrite, while Llano del Banco continued to issue basanite. The eruption ended with Duraznero erupting basanite with abundant crustal and mantle xenoliths. The tephrites and basanites from Duraznero and Llano del Banco show narrow compositional ranges and define a bimodal suite. Each batch ascended and evolved separately without significant intermixing, as did the Hoyo Negro basanite, which formed at lower degrees of melting. The magmas fractionated clinopyroxene +olivine±kaersutite±Ti-magnetite at 600-800 MPa and possibly 800-1100 MPa. Abundant reversely zoned phenocrysts reflect mixing with evolved melts at mantle depths. Probably as early as 1936, Hoyo Negro basanite entered the deep rift system at 200-350 MPa. Some shallower pockets of this basanite evolved to phonotephrite through differentiation and assimilation of wall rock. A few months prior to eruption, a mixing event in the mantle may have triggered the final ascent of the magmas. Most of the erupted tephrite and basanite ascended from mantle depths within hours to days without prolonged storage in crustal reservoirs. The Cumbre Vieja rift zone differs from the rift zones of Kilauea volcano (Hawaii) in lacking a summit caldera or a summit reservoir feeding the rift system and in being smaller and less active with most of the rift magma solidifying between eruptions.

Ectopic Compound Odontoma in the Buccal Mucosa: Report of a Rare Case

Directory of Open Access Journals (Sweden)

Aparna Venigalla

2015-01-01

Full Text Available Eruption of tooth into extraosseous locations is an extremely rare condition. We report a case of a six-year-old girl child with tooth-like structure erupting from the right buccal mucosa. Clinical, radiographic, and histopathologic examination suggested the diagnosis of compound odontoma. Very few cases have been reported so far, where tooth has been located completely in the soft tissue and a variety of names have been used for that condition. A brief review of the literature and the ambiguity in naming the situation is discussed.

Solar filament material oscillations and drainage before eruption

International Nuclear Information System (INIS)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Dan; Yang, Bo

2014-01-01

Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar filament are associated with the flow of material along the filament axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a filament eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the Hα images from the Global Oscillation Network Group. Hours before the eruption, the filament was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the filament relative to the solar surface. After the active phase, LAL oscillations were observed in the inclined filament. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the filament evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of filament material was drained toward one filament endpoint, followed immediately by the violent eruption of the filament. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the filament material drainage could play a role in the transition from a slow to a fast rise of the erupting filament.

Can rain cause volcanic eruptions?

Science.gov (United States)

Mastin, Larry G.

1993-01-01

Volcanic eruptions are renowned for their violence and destructive power. This power comes ultimately from the heat and pressure of molten rock and its contained gases. Therefore we rarely consider the possibility that meteoric phenomena, like rainfall, could promote or inhibit their occurrence. Yet from time to time observers have suggested that weather may affect volcanic activity. In the late 1800's, for example, one of the first geologists to visit the island of Hawaii, J.D. Dana, speculated that rainfall influenced the occurrence of eruptions there. In the early 1900's, volcanologists suggested that some eruptions from Mount Lassen, Calif., were caused by the infiltration of snowmelt into the volcano's hot summit. Most such associations have not been provable because of lack of information; others have been dismissed after careful evaluation of the evidence.

A time series of filament eruptions observed by three eyes from space: from failed to successful eruptions

International Nuclear Information System (INIS)

Shen Yuandeng; Liu Yu; Liu Rui

2011-01-01

We present stereoscopic observations of six sequential eruptions of a filament in the active region NOAA 11045 on 2010 Feb 8, with the advantage of the STEREO twin viewpoints in combination with Earth's viewpoint from SOHO instruments and ground-based telescopes. The last one of the six eruptions is a coronal mass ejection, but the others are not. The flare in this successful one is more intense than in the others. Moreover, the velocity of filament material in the successful one is also the largest among them. Interestingly, all the filament velocities are found to be proportional to the power of their flares. We calculate magnetic field intensity at low altitude, the decay indexes of the external field above the filament, and the asymmetry properties of the overlying fields before and after the failed eruptions and find little difference between them, indicating the same coronal confinement exists for both the failed and successful eruptions. The results suggest that, besides the confinement of the coronal magnetic field, the energy released in the low corona should be another crucial element affecting a failed or successful filament eruption. That is, a coronal mass ejection can only be launched if the energy released exceeds some critical value, given the same initial coronal conditions.

Tooth cusp sharpness as a dietary correlate in great apes.

Science.gov (United States)

Berthaume, Michael A

2014-02-01

Mammalian molars have undergone heavy scrutiny to determine correlates between morphology and diet. Here, the relationship between one aspect of occlusal morphology, tooth cusp radius of curvature (RoC), and two broad dietary categories, folivory and frugivory, is analyzed in apes. The author hypothesizes that there is a relationship between tooth cusp RoC and diet, and that folivores have sharper teeth than frugivores, and further test the correlation between tooth cusp RoC and tooth cusp size. Eight measures of tooth cusp RoC (two RoCs per cusp) were taken from 53 M(2) s from four species and subspecies of frugivorous apes (Pongo pygmaeus, Pan troglodytes troglodytes, Pan troglodytes schweinfurthii, and Gorilla gorilla gorilla) and two subspecies of folivorous apes (Gorilla beringei beringei, and Gorilla beringei graueri). Phylogenetically corrected ANOVAs were run on the full dataset and several subsets of the full dataset, revealing that, when buccolingual RoCs are taken into account, tooth cusp RoCs can successfully differentiate folivores and frugivores. PCAs revealed that folivores consistently had duller teeth than frugivores. In addition, a weak, statistically significant positive correlation exists between tooth cusp size and tooth cusp RoC. The author hypothesizes differences in tooth cusp RoC are correlated with wear rates, where, per vertical unit of wear, duller cusps will have a longer length of exposed enamel ridge than sharper cusps. More data need to be gathered to determine if the correlation between tooth cusp RoC and tooth cusp size holds true when small primates are considered. Copyright © 2013 Wiley Periodicals, Inc.

Seismo-acoustic evidence for an avalanche driven phreatic eruption through a beheaded hydrothermal system: An example from the 2012 Tongariro eruption

Science.gov (United States)

Jolly, A.D.; Jousset, P.; Lyons, J.J.; Carniel, R.; Fournier, R.; Fry, B.; Miller, C.

2016-01-01

The 6 August 2012 Te Maari eruption comprises a complex eruption sequence including multiple eruption pulses, a debris avalanche that propagated ~ 2 km from the vent, and the formation of a 500 m long, arcuate chasm, located ~ 300 m from the main eruption vent. The eruption included 6 distinct impulses that were coherent across a local infrasound network marking the eruption onset at 11:52:18 (all times UTC). An eruption energy release of ~ 3 × 1012 J was calculated using a body wave equation for radiated seismic energy. A similar calculation based on the infrasound record, shows that ~ 90% of the acoustic energy was released from three impulses at onset times 11:52:20 (~ 20% of total eruption energy), 11:52:27 (~ 50%), and 11:52:31 (~ 20%). These energy impulses may coincide with eyewitness accounts describing an initial eastward directed blast, followed by a westward directed blast, and a final vertical blast. Pre-eruption seismic activity includes numerous small unlocatable micro-earthquakes that began at 11:46:50. Two larger high frequency earthquakes were recorded at 11:49:06 and 11:49:21 followed directly by a third earthquake at 11:50:17. The first event was located within the scarp based on an arrival time location from good first P arrival times and probably represents the onset of the debris avalanche. The third event was a tornillo, characterised by a 0.8 Hz single frequency resonance, and has a resonator attenuation factor of Q ~ 40, consistent with a bubbly fluid filled resonator. This contrasts with a similar tornillo event occurring 2.5 weeks earlier having Q ~ 250–1000, consistent with a dusty gas charged resonator. We surmise from pre-eruption seismicity, and the observed attenuation change, that the debris avalanche resulted from the influx of fluids into the hydrothermal system, causing destabilisation and failure. The beheaded hydrothermal system may have then caused depressurisation frothing of the remaining gas charged system leading to the

Life of a Tooth: A Visual Timeline

Medline Plus

Full Text Available ... Dentist Your Family's Oral Health About the AGD Dental care and oral health information you need from ... Menstrual Calendar for Tooth Extraction Learn what those dental words mean. The Life of a Tooth Home | ...

Global Significant Volcanic Eruptions Database, 4360 BC to present

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Significant Volcanic Eruptions Database is a global listing of over 600 eruptions from 4360 BC to the present. A significant eruption is classified as one that...

Is gingival recession a consequence of an orthodontic tooth size and/or tooth position discrepancy? "A paradigm shift".

Science.gov (United States)

Richman, Colin

2011-01-01

Gingival recession (GR) is a commonly observed dental lesion. The underlying etiology has not been clearly identified, although several theories have been suggested. Tooth crowding or tooth malalignment is also frequently observed, with both conditions appearing to be more prevalent in developed countries with heterogeneous populations. A total of 25 consecutively treated patients representing 72 teeth and demonstrating facial clinical GR of > 3 mm were examined clinically, photographically, and with 3-dimensional radiology using conebeam computed tomography. All examined teeth presented with normal interproximal probing depths and attachment levels (teeth demonstrating > 3 mm of GR presented with significantly prominent facial tooth contours and associated alveolar bone dehiscences. Most involved teeth presented with their root structures extending beyond the facial alveolar bony housing (fenestrations). This represents a discrepancy between tooth size and alveolar bone dimensions in the buccolingual, axial, and sagittal orientation. Fewer involved teeth were malpositioned toward the buccal aspect. Both conditions were associated with facial alveolar bone dehiscences and associated GR. This study suggests tooth volume and/or tooth position within the alveolar bony housing strongly correlate with GR. All nonperiodontitis-involved teeth with GR were associated with either wider teeth or facially aligned teeth. However, it is emphasized that all facially aligned teeth, or "larger" teeth, do not necessarily present with GR. Based on these findings, the radiographic-supporting bone index is proposed. This index should facilitate appropriate evaluation of the alveolar bone supporting the mucogingival complex, both on the facial and lingual aspect of teeth. Further investigations are needed to support these preliminary data.

Gastroesophageal Reflux Disease and Tooth Erosion

Directory of Open Access Journals (Sweden)

Sarbin Ranjitkar

2012-01-01

Full Text Available The increasing prevalence of gastroesophageal reflux disease (GERD in children and adults, and of “silent refluxers” in particular, increases the responsibility of dentists to be alert to this potentially severe condition when observing unexplained instances of tooth erosion. Although gastroesophageal reflux is a normal physiologic occurrence, excessive gastric and duodenal regurgitation combined with a decrease in normal protective mechanisms, including an adequate production of saliva, may result in many esophageal and extraesophageal adverse conditions. Sleep-related GERD is particularly insidious as the supine position enhances the proximal migration of gastric contents, and normal saliva production is much reduced. Gastric acid will displace saliva easily from tooth surfaces, and proteolytic pepsin will remove protective dental pellicle. Though increasing evidence of associations between GERD and tooth erosion has been shown in both animal and human studies, relatively few clinical studies have been carried out under controlled trial conditions. Suspicion of an endogenous source of acid being associated with observed tooth erosion requires medical referral and management of the patient as the primary method for its prevention and control.

Tooth positioners and their effects on treatment outcome.

Science.gov (United States)

Pravindevaprasad, A; Therese, Beena Agnes

2013-07-01

Malocclusion can also be corrected by means of clear removable appliances called as "tooth positioners" or "aligners". A tooth positioner is used to control settling and to minimize or eliminate relapse of the teeth after an orthodontic treatment. In this article, a complete review of the objectives, course of treatment, fabrication, and the materials used for fabrication of tooth positioners along with their importance and disadvantages were discussed. Tooth positioners did improve the overall orthodontic treatment outcome as quantified by the ABO (American Board of orthodontics) objective scoring method. But once the initial occlusal contact was achieved, the vertical movement of teeth was found to be inhibited.

Tooth-marked small theropod bone: an extremely rare trace

DEFF Research Database (Denmark)

Jacobsen, Aase Roland

2001-01-01

Tooth-marked dinosaur bones provide insight into feeding behaviours and biting strategies of theropod dinosaurs. The majority of theropod tooth marks reported to date have been found on herbivorous dinosaur bones, although some tyrannosaurid bones with tooth marks have also been reported. In 1988...

Association between Severity of Tooth Wear and Dentinal Hypersensitivity

Directory of Open Access Journals (Sweden)

Ashok Ayer

2016-11-01

Full Text Available Background & Objectives: Tooth wear (attrition, abrasion, erosion, and abfraction is perceived globally as ever increasing problem. Several outcome of the tooth wear are hypersensitivity, esthetic problems, functional impairment, annoyance to the patient, and fracture of the tooth. Among these, the measurable and more commonly reported outcome is hypersensitivity to stimuli. Although dentin hypersensitivity is a common clinical condition and is generally reported by the patient after experiencing a sharp, short pain caused by one of the several different external stimuli, it is often inadequately understood. None of the scientific literature available till date attempted to establish the relationship between tooth wear and dentin hypersensitivity which could be a key factor in monitoring those patients.  The aim of the study was to estimate the association between severity of teeth wear and sensitivity in the patients with reported dentinal hypersensitivity.Materials & Methods: Fifty patients with dentin hypersensitivity were investigated for tooth wear. Tooth wear measured using exact tooth wear index and level of sensitivity to stimuli was recorded using a numerical rating scale. Results: Enamel wear at cervical region of teeth showed a positive correlation (p=.010, similarly, dentin wear at cervical region of teeth showed positive correlation and significant association (p<.001 with dentinal hypersensitivity.Conclusion: The observation supports a significant association between severities of tooth surface wear and dentinal hypersensitivity.

Relationships between mineralization and silicic volcanism in the central Andes

Science.gov (United States)

Francis, P. W.; Halls, C.; Baker, M. C. W.

1983-01-01

Existing models for the genesis of porphyry copper deposits indicate that they formed in granodioritic stocks located in the infrastructure of andesitic stratovolcanoes. It is noted that sites of porphyry-type subvolcanic tin mineralization in the Eastern Cordillera of Bolivia are distinguished by the absence of such andesitic structures. The surface expression of a typical subvolcanic porphyry tin deposit is thought to be an extrusive dome of quartz latite porphyry, sometimes related to a larger caldera structure. Evidence from the El Salvador porphyry copper deposit in the Eocene magmatic belt in Chile indicates that it too may be more closely related to a silicic volcanic structure than to an andesitic stratovolcano. The dome of La Soufriere, Guadeloupe is offered as a modern analog for the surface expression of subvolcanic mineralization processes, with the phreatic eruptions there indicating the formation of hydrothermal breccia bodies in depths. It is pointed out that the occurrence of mineralized porphyries, millions of years after caldera formation, does not necessarily indicate that tin intrusions and mineralization are not genetically related to the subcaldera pluton, but may be a consequence of the long thermal histories (1-10 million years) of the lowermost parts of large plutons.

Stress-induced comenditic trachyte effusion triggered by trachybasalt intrusion: multidisciplinary study of the AD 1761 eruption at Terceira Island (Azores)

Science.gov (United States)

Pimentel, A.; Zanon, V.; de Groot, L. V.; Hipólito, A.; Di Chiara, A.; Self, S.

2016-03-01

The AD 1761 eruption on Terceira was the only historical subaerial event on the island and one of the last recorded in the Azores. The eruption occurred along the fissure zone that crosses the island and produced a trachybasalt lava flow and scoria cones. Small comenditic trachyte lava domes (known as Mistérios Negros) were also thought by some to have formed simultaneously on the eastern flank of Santa Bárbara Volcano. Following a multidisciplinary approach, we combined geological mapping, paleomagnetic, petrographic, mineral and whole-rock geochemical and structural analyses to study this eruption. The paleomagnetic dating method compared geomagnetic vectors (directions and intensities) recorded by both the AD 1761 lava flow and Mistérios Negros domes and revealed that the two events were indeed coeval. Based on new data and interpretation of historical records, we have accordingly reconstructed the AD 1761 eruptive dynamics and distinguished three phases: (1) a precursory phase characterized by decreased degassing in the fumarolic field of Pico Alto Volcano and a gradual increase of seismic activity, which marked the intrusion of trachybasalt magma; (2) a first eruptive phase that started with phreatic explosions on the eastern flank of Santa Bárbara Volcano, followed by the inconspicuous effusion of comenditic trachyte (66 wt% SiO2), forming a WNW-ESE-oriented chain of lava domes; and (3) a second eruptive phase on the central part of the fissure zone, where a Hawaiian to Strombolian-style eruption formed small scoria cones (E-W to ENE-WSW-oriented) and a trachybasalt lava flow (50 wt% SiO2) which buried 27 houses in Biscoitos village. Petrological analyses show that the two batches of magma were emitted independently without evidence of interaction. We envisage that the dome-forming event was triggered by local stress changes induced by intrusion of the trachybasalt dyke along the fissure zone, which created tensile stress conditions that promoted ascent

Life of a Tooth: A Visual Timeline

Medline Plus

Full Text Available ... Child First See a Dentist? The History of Dental Advances Why is Oral Health Important for Men? What is Baby Bottle Tooth Decay? Learn what those dental words mean. The Life of a Tooth Home | ...

Inhibitory effect of interferon-γ on experimental tooth movement in mice.

Science.gov (United States)

Kohara, Haruka; Kitaura, Hideki; Yoshimatsu, Masako; Fujimura, Yuji; Morita, Yukiko; Eguchi, Toshiko; Yoshida, Noriaki

2012-09-01

The aim of this study was to investigate the effects of interferon (IFN)-γ on experimental tooth movement in mice using a murine experimental tooth movement model. An Ni-Ti closed-coil spring was inserted between the upper-anterior alveolar bones and the upper-left first molars in mice. We evaluated the relationship between local Ifn-γ mRNA levels and orthodontic tooth movement. In other experiments, IFN-γ was injected adjacent to each first molar every other day during tooth movement. After 12 days, the amount of tooth movement was measured. Tartrate-resistant acid phosphatase (TRAP)-positive cells at the pressure side of each experimental tooth were counted as osteoclasts. Local Ifn-γ mRNA expression increased with orthodontic tooth movement. The number of TRAP-positive cells increased on the pressure side of the first molar. In contrast, the degree of tooth movement and the number of TRAP-positive cells on the pressure side in IFN-γ-injected mice were less than those of control mice. IFN-γ was induced in experimental tooth movement, and could inhibit mechanical force-loaded osteoclastogenesis and tooth movement. These results suggest that IFN-γ might be useful in controlling orthodontic tooth movement because of its inhibitory action on excessive osteoclastogenesis during this movement.

Tooth bleaching and young adults in Nigeria: knowledge, experiences and intention.

Science.gov (United States)

Azodo, C C; Ogbomo, A C; Agbor, M A

2012-12-01

To assess the knowledge, experiences and intention to have tooth bleaching among young adults studying in a Nigerian University. A cross-section of part-time undergraduate students of University of Benin, Benin City, Nigeria were studied in 2010 using a self-administered questionnaire. About three-quarters 289 (72.4%) of the respondents reported awareness of at least one cause of tooth discoloration. A total of 143 (35.8%) of the respondents have heard of tooth bleaching with main sources of information being friends/relatives, dentists and the internet. One-third 132 (33.1%) of the respondents correctly identified that the aim of tooth bleaching was to make the teeth whiter. The respondents that had correct knowledge about mechanism, duration and complications of tooth bleaching were 51 (12.8%), 25 (6.3%) and 35 (8.8%) respectively. The major perceived benefits of tooth bleaching reported by the respondents were self confidence boost 152 (38.1%) and improvement of one's beauty 107 (26.8%). Out of the 68 (17.0%) respondents that have attempted tooth bleaching, 36 (52.9%) used tooth whitening toothpaste. Out of the 151 (37.8%) respondents that expressed intention of having tooth bleaching procedure, 32 (21.2%) would pursue the course, no matter the cost. In the studied population, knowledge of tooth discoloration was high, awareness and experiences of tooth bleaching were low but significant number expressed intention of having tooth bleaching. It is important that dentists increase oral health information particularly tooth bleaching information accessibility to the young adult population to improve the knowledge and prevent adverse effects.

Tranexamic acid-induced fixed drug eruption

Directory of Open Access Journals (Sweden)

Natsuko Matsumura

2015-01-01

Full Text Available A 33-year-old male showed multiple pigmented patches on his trunk and extremities after he took tranexamic acid for common cold. He stated that similar eruptions appeared when he was treated with tranexamic acid for influenza 10 months before. Patch test showed positive results at 48 h and 72 h by 1% and 10% tranexamic acid at the lesional skin only. To our knowledge, nine cases of fixed drug eruption induced by tranexamic acid have been reported in Japan. Tranexamic acid is a safe drug and frequently used because of its anti-fibrinolytic and anti-inflammatory effects, but caution of inducing fixed drug eruption should be necessary.

Magmatic Ascent and Eruption Processes on Mercury

Science.gov (United States)

Head, J. W.; Wilson, L.

2018-05-01

MESSENGER volcanic landform data and information on crustal composition allow us to model the generation, ascent, and eruption of magma; Mercury explosive and effusive eruption processes differ significantly from other terrestrial planetary bodies.

Technique: imaging earliest tooth development in 3D using a silver-based tissue contrast agent.

Science.gov (United States)

Raj, Muhammad T; Prusinkiewicz, Martin; Cooper, David M L; George, Belev; Webb, M Adam; Boughner, Julia C

2014-02-01

Looking in microscopic detail at the 3D organization of initiating teeth within the embryonic jaw has long-proved technologically challenging because of the radio-translucency of these tiny un-mineralized oral tissues. Yet 3D image data showing changes in the physical relationships among developing tooth and jaw tissues are vital to understand the coordinated morphogenesis of vertebrate teeth and jaws as an animal grows and as species evolve. Here, we present a new synchrotron-based scanning solution to image odontogenesis in 3D and in histological detail using a silver-based contrast agent. We stained fixed, intact wild-type mice aged embryonic (E) day 10 to birth with 1% Protargol-S at 37°C for 12-32 hr. Specimens were scanned at 4-10 µm pixel size at 28 keV, just above the silver K-edge, using micro-computed tomography (µCT) at the Canadian Light Source synchrotron. Synchrotron µCT scans of silver-stained embryos showed even the earliest visible stages of tooth initiation, as well as many other tissue types and structures, in histological detail. Silver stain penetration was optimal for imaging structures in intact embryos E15 and younger. This silver stain method offers a powerful yet straightforward approach to visualize at high-resolution and in 3D the earliest stages of odontogenesis in situ, and demonstrates the important of studying the tooth organ in all three planes of view. Copyright © 2013 Wiley Periodicals, Inc.

Tooth Decay Process: How to Reverse It and Avoid a Cavity

Science.gov (United States)

... Health Info Health Topics Tooth Decay Tooth decay (dental caries) is damage to a tooth that can happen ... Clinical Trials Show All Clinical Trials Data & Statistics Dental caries (tooth decay) remains the most prevalent chronic disease ...

Tooth polishing: The current status

Directory of Open Access Journals (Sweden)

Madhuri Alankar Sawai

2015-01-01

Full Text Available Healthy teeth and gums make a person feel confident and fit. As people go about their daily routines and with different eating and drinking habits, the tooth enamel turns yellowish or gets stained. Polishing traditionally has been associated with the prophylaxis procedure in most dental practices, which patients know and expect. However, with overzealous use of polishing procedure, there is wearing of the superficial tooth structure. This would lead to more accumulation of local deposits. Also, it takes a long time for the formation of the fluoride-rich layer of the tooth again. Hence, now-a-days, polishing is not advised as a part of routine oral prophylaxis procedure but is done selectively based on the patients′ need. The article here, gives an insight on the different aspects of the polishing process along with the different methods and agents used for the same.

Unambiguous Evidence of Filament Splitting-induced Partial Eruptions

Science.gov (United States)

Cheng, X.; Kliem, B.; Ding, M. D.

2018-03-01

Coronal mass ejections are often considered to result from the full eruption of a magnetic flux rope (MFR). However, it is recognized that, in some events, the MFR may release only part of its flux, with the details of the implied splitting not completely established due to limitations in observations. Here, we investigate two partial eruption events including a confined and a successful one. Both partial eruptions are a consequence of the vertical splitting of a filament-hosting MFR involving internal reconnection. A loss of equilibrium in the rising part of the magnetic flux is suggested by the impulsive onset of both events and by the delayed onset of reconnection in the confined event. The remaining part of the flux might be line-tied to the photosphere in a bald patch (BP) separatrix surface, and we confirm the existence of extended BP sections for the successful eruption. The internal reconnection is signified by brightenings in the body of one filament and between the rising and remaining parts of both filaments. It evolves quickly into the standard current sheet reconnection in the wake of the eruption. As a result, regardless of being confined or successful, both eruptions produce hard X-ray sources and flare loops below the erupting but above the surviving flux, as well as a pair of flare ribbons enclosing the latter.

Eruptive viscosity and volcano morphology

International Nuclear Information System (INIS)

Posin, S.B.; Greeley, R.

1988-01-01

Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology

Towards forecasting volcanic eruptions on a global scale

Science.gov (United States)

Hooper, A. J.; Heimisson, E. R.; Gaddes, M.; Bagnardi, M.; Sigmundsson, F.; Spaans, K.; Parks, M.; Gudmundsson, M. T.; Ebmeier, S. K.; Holohan, E. P.; Wright, T. J.; Jonsdottir, K.; Hreinsdottir, S.; Dumont, S.; Ofeigsson, B.; Vogfjord, K. S.

2016-12-01

Volcanic eruptions can cause loss of life, damage health, and have huge economic impacts, providing strong societal motivation for predicting eruptive behavior prior to and during eruptions. I will present here recent progress we have made in mechanical modelling with a predictive capacity, and how we are expanding volcano monitoring to a global scale. The eruption of Bardarbunga volcano, Iceland, in 2014-2015 was the largest eruption there for more than 200 years, producing 1.6 km3of lava. Prior to eruption, magma propagated almost 50 km beneath the surface, over a period of two weeks. Key questions to answer in advance of such eruptions are: will it erupt, where, how much and for how long? We developed a model based on magma taking a path that maximizes energy release, which aligns well with the actual direction taken. Our model also predicts eruption in a topographic low, as actually occurred. As magma was withdrawn, the volcano surface sagged downwards. A coupled model of magma flow and piston-like collapse predicts a declining magma flow rate and ground subsidence rate, in accordance with that observed. With such a model, observations can be used to predict the timescale and rates of eruption, even before one starts. The primary data needed to constrain these predictive models are measurements of surface deformation. In Iceland, this is achieved using high accuracy GPS, however, most volcanoes have no ground instrumentation. A recent ESA mission, Sentinel-1, can potentially image deformation at almost all subaerial volcanoes every 6 days, using a technique called interferometric synthetic aperture radar (InSAR). This will allow us to detect early stages of magma migration at any volcano, then task other satellites to acquire data at a higher rate. We are working on a system to process all Sentinel-1 data in near-real time, which is a big data challenge. We have also developed new algorithms that maximize signal extraction from each new acquisition and

Cracked tooth syndrome: A report of three cases.

Science.gov (United States)

Sadasiva, Kadandale; Ramalingam, Sathishmuthukumar; Rajaram, Krishnaraj; Meiyappan, Alagappan

2015-08-01

Cracked tooth syndrome (CTS), the term was coined by Cameron in 1964, which refers to an incomplete fracture of a vital posterior tooth extending to the dentin and occasionally into the pulp. CTS has always been a nightmare to the patient because of its unpredictable symptoms and a diagnostic dilemma for the dental practitioner due to its variable, bizarre clinical presentation. The treatment planning and management of CTS has also given problems and challenges the dentist as there is no specific treatment option. The management of CTS varies from one case to another or from one tooth to another in the same individual based on the severity of the symptoms and depth of tooth structure involved. After all, the prognosis of such tooth is still questionable and requires continuous evaluation. This article aims at presenting a series three cases of CTS with an overview on the clinical presentation, diagnosis and the different treatment options that varies from one case to another.

Factors associated with tooth loss and prosthodontic status among Sudanese adults.

Science.gov (United States)

Khalifa, Nadia; Allen, Patrick F; Abu-bakr, Neamat H; Abdel-Rahman, Manar E

2012-01-01

A study was conducted to determine the degree of tooth loss, factors influencing tooth loss, and the extent of prosthodontic rehabilitation in Sudanese adults (≥ 16 years old) attending outpatient clinics in Khartoum State. Pearson and multivariate analyses were used to examine the relationships between tooth loss and specific characteristics determined through interviews and clinical examinations. The mean number of missing teeth was 3.6 (SD, 4.9) and the prevalence of edentulism was 0.1%. The prevalence of tooth loss (missing at least one tooth) was 78%; 66.9% of tooth loss was due to caries, and 11.2% was attributable to other reasons. Prosthetic replacement of missing teeth was evident in 3%, whereas a need for prosthetic replacement was evident in 57%. Having teeth was associated with age, gender, and socioeconomic status; tooth loss due to caries was associated with age, tribe, frequency of tooth-brushing, and a low rate of dental consultation. Tooth loss due to other reasons was associated with age, tribe, education, periodontal pocketing, tobacco use, tooth wear, and prosthetic status. The results of the present study indicated that the major cause of tooth loss was dental caries, thus emphasizing the importance of a public prevention-based healthcare program. Replacement of missing teeth was uncommon in the study subjects, which may reflect lack of access to this type of oral healthcare.

Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride

Science.gov (United States)

Kierdorf, Uwe; Death, Clare; Hufschmid, Jasmin; Witzel, Carsten; Kierdorf, Horst

2016-01-01

Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species. PMID:26895178

Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus Exposed to High Environmental Levels of Fluoride.

Directory of Open Access Journals (Sweden)

Uwe Kierdorf

Full Text Available Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species.

Contaminated tooth brushes-potential threat to oral and general health

Directory of Open Access Journals (Sweden)

Rashmi Naik

2015-01-01

Full Text Available Background: Tooth brushing is most common method of maintaining oral hygiene. In removing plaque and other soft debris from the teeth, tooth brushes become contaminated with bacteria, blood, saliva and oral debris. These contaminated tooth brushes can be a source of infection. Aims and objectives: The aim of the present study was to evaluate the presence of microorganisms in the tooth brushes and to investigate the effect of disinfectants such as chlorhexidine gluconate, sodium hypochlorite and water to decontaminate them. Materials and Methods: Twenty-one children were asked to brush their teeth for 5 days with a tooth brush. The tooth brushes were put in Robertson′s Cooked Meat broth and were observed for growth of Streptococcal microorganisms. These tooth brushes were then placed in disinfectants such as 0.2% chlorhexidine gluconate (Group I, 1% sodium hypochlorite (Group II and water (Group III for 24 hrs and then cultured again. Reduction of growth of microorganisms was seen in Group I, Group II and remnants of growth seen in Group III. Conclusion: We conclude that the use of disinfectant for a tooth brush is a must for every individual at least at regular intervals.

Histological evidence for a dynamic dental battery in hadrosaurid dinosaurs.

Science.gov (United States)

Bramble, Katherine; LeBlanc, Aaron R H; Lamoureux, Denis O; Wosik, Mateusz; Currie, Philip J

2017-11-17

The first histological study of an entire hadrosaurid dental battery provides a comprehensive look at tooth movement within this complex structure. Previous studies have focused on isolated teeth, or in-situ batteries, but this is the first study to examine an entire dental battery of any dinosaur. The absence of direct tooth-to-tooth contact across the entire battery and a unique arrangement of the dental tissues in hadrosaurids led us to compare their teeth with the ever-growing incisors of mammals. The similarity in the distributions of tissues along the incisor, coupled with continuous eruption, make for helpful comparisons to hadrosaurid teeth. The mammalian ever-growing incisor can be used as a model to extrapolate the soft tissue connections and eruptive mechanisms within the hadrosaurid dental battery. Serial sections across the adult dental battery reveal signs of gradual ontogenetic tooth migration. Extensive remodeling of the alveolar septa and the anteroposterior displacement of successive generations of teeth highlight the gradual migration of tooth generations within the battery. These eruptive and ontogenetic tooth movements would not be possible without a ligamentous connection between successive teeth and the jaws, underscoring the dynamic nature of one of the most unique and complex dental systems in vertebrate history.

Effect of Melamine Sponge on Tooth Stain Removal.

Science.gov (United States)

Otsuka, Takero; Kawata, Toshitsugu

2015-01-01

To investigate the stain removal ability of melamine sponge before aesthetic tooth whitening in extracted teeth. Melamine sponge of thickness 40 mm was compressed and the destruction of the partition wall structure during the compression process was examined under a stereoscopic microscope. An extracted human tooth was cleaned by normal polishing or with melamine sponge for 90 s. To evaluate the stain level, the tooth surfaces were photographed under a stereoscopic microscope at 0, 30, 60 and 90 s. The residual stained region was traced in a high-magnification photograph, and the stain intensity was presented as a change, relative to the intensity before the experiment (0 s). Mechanical cleaning by toothbrushing produced polishing scratches on the tooth surface, whereas use of the melamine sponge resulted in only minimal scratches. As the compression level increased, the stain-removing effect tended to become stronger. Melamine sponge can remove stains from the tooth surface more effectively and less invasively compared to a conventional toothbrush. As no new scratches are made on the tooth surface when using a melamine sponge brush, the risk of re-staining is reduced. Cleaning using a melamine sponge brush can be easily and effectively performed at home and in a dental office.

An automatic tooth preparation technique: A preliminary study

Science.gov (United States)

Yuan, Fusong; Wang, Yong; Zhang, Yaopeng; Sun, Yuchun; Wang, Dangxiao; Lyu, Peijun

2016-04-01

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W, and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head, and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software, and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05-0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm, and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

Drawing the Curtain on Enceladus' South-Polar Eruptions

Science.gov (United States)

Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R.; Berkson, Emily E.; Platts, Symeon S.

2015-11-01

For a comprehensive description of Enceladus' south-polar eruptions observed at high resolution, they must be represented as broad curtains rather than discrete jets. Meanders in the fractures from which the curtains of material erupt give rise to optical illusions that look like discrete jets, even along fractures with no local variations in eruptive activity, implying that many features previously identified as "jets" are in fact phantoms. By comparing Cassini images with model curtain eruptions, we are able to obtain maps of eruptive activity that are not biased by the presence of those phantom jets. The average of our activity maps over all times agrees well with thermal maps produced by Cassini CIRS. We can best explain the observed curtains by assuming spreading angles with altitude of up to 14° and zenith angles of up to 8°, for curtains observed in geometries that are sensitive to those quantities.

Evaluation of the distortion rate of panoramic and peri apical radiographs in erupted third molar inclination

International Nuclear Information System (INIS)

Ezoddini Ardakani, F.; Zangouie Booshehri, M.; Behniafar, B.

2011-01-01

Panoramic and peri apical radiographs are normally used in impacted third molar teeth surgeries. The aim of the present study was to evaluate and compare the distortion of the erupted third molar teeth on panoramic and peri apical radiographs. Patients and Methods: A total of 44 radiographs were obtained of 22 patients (age range, 18-24 years) referred to the faculty of dentistry for orthodontic treatment. A plaster cast was prepared and panoramic radiography was taken for all patients to plan the orthodontic treatment and peri apical radiography was taken for investigation of tooth structure details. Therefore, a total of 66 views and samples were studied by two methods: 1) Measuring the angle between the longitudinal plane of the third molar and occlusal plane. 2) Measuring the angle between the longitudinal plane of second and third molar. Finally, 132 records were evaluated by one individual. Results: There was no significant statistical difference between the mean position of the third molar on panoramic, peri apical radiographs and the casts. However, measurements of the third molars on peri apical radiographs were slightly closer to the measurements of the casts compared to the panoramic radiographs. Conclusion: Distortion does not have a specific effect on the diagnosis of the position of the third erupted molars by peri apical or panoramic radiographs, though various studies have shown that these radiographs have an amount of distortion and peri apical radiographical distortion is less than that in panoramic radiography.

Protein- mediated enamel mineralization

Science.gov (United States)

Moradian-Oldak, Janet

2012-01-01

Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth. PMID:22652761

Periodontal profile classes predict periodontal disease progression and tooth loss.

Science.gov (United States)

Morelli, Thiago; Moss, Kevin L; Preisser, John S; Beck, James D; Divaris, Kimon; Wu, Di; Offenbacher, Steven

2018-02-01

Current periodontal disease taxonomies have limited utility for predicting disease progression and tooth loss; in fact, tooth loss itself can undermine precise person-level periodontal disease classifications. To overcome this limitation, the current group recently introduced a novel patient stratification system using latent class analyses of clinical parameters, including patterns of missing teeth. This investigation sought to determine the clinical utility of the Periodontal Profile Classes and Tooth Profile Classes (PPC/TPC) taxonomy for risk assessment, specifically for predicting periodontal disease progression and incident tooth loss. The analytic sample comprised 4,682 adult participants of two prospective cohort studies (Dental Atherosclerosis Risk in Communities Study and Piedmont Dental Study) with information on periodontal disease progression and incident tooth loss. The PPC/TPC taxonomy includes seven distinct PPCs (person-level disease pattern and severity) and seven TPCs (tooth-level disease). Logistic regression modeling was used to estimate relative risks (RR) and 95% confidence intervals (CI) for the association of these latent classes with disease progression and incident tooth loss, adjusting for examination center, race, sex, age, diabetes, and smoking. To obtain personalized outcome propensities, risk estimates associated with each participant's PPC and TPC were combined into person-level composite risk scores (Index of Periodontal Risk [IPR]). Individuals in two PPCs (PPC-G: Severe Disease and PPC-D: Tooth Loss) had the highest tooth loss risk (RR = 3.6; 95% CI = 2.6 to 5.0 and RR = 3.8; 95% CI = 2.9 to 5.1, respectively). PPC-G also had the highest risk for periodontitis progression (RR = 5.7; 95% CI = 2.2 to 14.7). Personalized IPR scores were positively associated with both periodontitis progression and tooth loss. These findings, upon additional validation, suggest that the periodontal/tooth profile classes and the derived

A FLUX ROPE ERUPTION TRIGGERED BY JETS

International Nuclear Information System (INIS)

Guo Juan; Zhang Hongqi; Deng Yuanyong; Lin Jiaben; Su Jiangtao; Liu Yu

2010-01-01

We present an observation of a filament eruption caused by recurrent chromospheric plasma injections (surges/jets) on 2006 July 6. The filament eruption was associated with an M2.5 two-ribbon flare and a coronal mass ejection (CME). There was a light bridge in the umbra of the main sunspot of NOAA 10898; one end of the filament was terminated at the region close to the light bridge, and recurrent surges were observed to be ejected from the light bridge. The surges occurred intermittently for about 8 hr before the filament eruption, and finally a clear jet was found at the light bridge to trigger the filament eruption. We analyzed the evolutions of the relative darkness of the filament and the loaded mass by the continuous surges quantitatively. It was found that as the occurrence of the surges, the relative darkness of the filament body continued growing for about 3-4 hr, reached its maximum, and kept stable for more than 2 hr until it erupted. If suppose 50% of the ejected mass by the surges could be trapped by the filament channel, then the total loaded mass into the filament channelwill be about 0.57x10 16 g with a momentum of 0.57x10 22 g cm s -1 by 08:08 UT, which is a non-negligible effect on the stability of the filament. Based on the observations, we present a model showing the important role that recurrent chromospheric mass injection play in the evolution and eruption of a flux rope. Our study confirms that the surge activities can efficiently supply the necessary material for some filament formation. Furthermore, our study indicates that the continuous mass with momentum loaded by the surge activities to the filament channel could make the filament unstable and cause it to erupt.

Characterize Eruptive Processes at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Valentine, G.

2001-01-01

This Analysis/Model Report (AMR), ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', presents information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a potential repository at Yucca Mountain. Many aspects of this work are aimed at resolution of the Igneous Activity Key Technical Issue (KTI) as identified by the Nuclear Regulatory Commission (NRC 1998, p. 3), Subissues 1 and 2, which address the probability and consequence of igneous activity at the proposed repository site, respectively. Within the framework of the Disruptive Events Process Model Report (PMR), this AMR provides information for the calculations in two other AMRs ; parameters described herein are directly used in calculations in these reports and will be used in Total System Performance Assessment (TSPA). Compilation of this AMR was conducted as defined in the Development Plan, except as noted. The report begins with considerations of the geometry of volcanic feeder systems, which are of primary importance in predicting how much of a potential repository would be affected by an eruption. This discussion is followed by one of the physical and chemical properties of the magmas, which influences both eruptive styles and mechanisms for interaction with radioactive waste packages. Eruptive processes including the ascent velocity of magma at depth, the onset of bubble nucleation and growth in the rising magmas, magma fragmentation, and velocity of the resulting gas-particle mixture are then discussed. The duration of eruptions, their power output, and mass discharge rates are also described. The next section summarizes geologic constraints regarding the interaction between magma and waste packages. Finally, they discuss bulk grain size produced by relevant explosive eruptions and grain shapes

Characterize Eruptive Processes at Yucca Mountain, Nevada

Energy Technology Data Exchange (ETDEWEB)

G. Valentine

2001-12-20

This Analysis/Model Report (AMR), ''Characterize Eruptive Processes at Yucca Mountain, Nevada'', presents information about natural volcanic systems and the parameters that can be used to model their behavior. This information is used to develop parameter-value distributions appropriate for analysis of the consequences of volcanic eruptions through a potential repository at Yucca Mountain. Many aspects of this work are aimed at resolution of the Igneous Activity Key Technical Issue (KTI) as identified by the Nuclear Regulatory Commission (NRC 1998, p. 3), Subissues 1 and 2, which address the probability and consequence of igneous activity at the proposed repository site, respectively. Within the framework of the Disruptive Events Process Model Report (PMR), this AMR provides information for the calculations in two other AMRs ; parameters described herein are directly used in calculations in these reports and will be used in Total System Performance Assessment (TSPA). Compilation of this AMR was conducted as defined in the Development Plan, except as noted. The report begins with considerations of the geometry of volcanic feeder systems, which are of primary importance in predicting how much of a potential repository would be affected by an eruption. This discussion is followed by one of the physical and chemical properties of the magmas, which influences both eruptive styles and mechanisms for interaction with radioactive waste packages. Eruptive processes including the ascent velocity of magma at depth, the onset of bubble nucleation and growth in the rising magmas, magma fragmentation, and velocity of the resulting gas-particle mixture are then discussed. The duration of eruptions, their power output, and mass discharge rates are also described. The next section summarizes geologic constraints regarding the interaction between magma and waste packages. Finally, they discuss bulk grain size produced by relevant explosive eruptions and grain

Beyond eruptive scenarios: assessing tephra fallout hazard from Neapolitan volcanoes.

Science.gov (United States)

Sandri, Laura; Costa, Antonio; Selva, Jacopo; Tonini, Roberto; Macedonio, Giovanni; Folch, Arnau; Sulpizio, Roberto

2016-04-12

Assessment of volcanic hazards is necessary for risk mitigation. Typically, hazard assessment is based on one or a few, subjectively chosen representative eruptive scenarios, which use a specific combination of eruptive sizes and intensities to represent a particular size class of eruption. While such eruptive scenarios use a range of representative members to capture a range of eruptive sizes and intensities in order to reflect a wider size class, a scenario approach neglects to account for the intrinsic variability of volcanic eruptions, and implicitly assumes that inter-class size variability (i.e. size difference between different eruptive size classes) dominates over intra-class size variability (i.e. size difference within an eruptive size class), the latter of which is treated as negligible. So far, no quantitative study has been undertaken to verify such an assumption. Here, we adopt a novel Probabilistic Volcanic Hazard Analysis (PVHA) strategy, which accounts for intrinsic eruptive variabilities, to quantify the tephra fallout hazard in the Campania area. We compare the results of the new probabilistic approach with the classical scenario approach. The results allow for determining whether a simplified scenario approach can be considered valid, and for quantifying the bias which arises when full variability is not accounted for.

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: A study of archived basaltic to rhyolitic ash samples

Science.gov (United States)

Damby, David; Horwell, Claire J.; Larsen, Gudrun; Thordarson, Thorvaldur; Tomatis, Maura; Fubini, Bice; Donaldson, Ken

2017-01-01

BackgroundThe eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations. MethodsA physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network. ResultsIcelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron

Safety issues of tooth whitening using peroxide-based materials.

Science.gov (United States)

Li, Y; Greenwall, L

2013-07-01

In-office tooth whitening using hydrogen peroxide (H₂O₂) has been practised in dentistry without significant safety concerns for more than a century. While few disputes exist regarding the efficacy of peroxide-based at-home whitening since its first introduction in 1989, its safety has been the cause of controversy and concern. This article reviews and discusses safety issues of tooth whitening using peroxide-based materials, including biological properties and toxicology of H₂O₂, use of chlorine dioxide, safety studies on tooth whitening, and clinical considerations of its use. Data accumulated during the last two decades demonstrate that, when used properly, peroxide-based tooth whitening is safe and effective. The most commonly seen side effects are tooth sensitivity and gingival irritation, which are usually mild to moderate and transient. So far there is no evidence of significant health risks associated with tooth whitening; however, potential adverse effects can occur with inappropriate application, abuse, or the use of inappropriate whitening products. With the knowledge on peroxide-based whitening materials and the recognition of potential adverse effects associated with the procedure, dental professionals are able to formulate an effective and safe tooth whitening regimen for individual patients to achieve maximal benefits while minimising potential risks.

Curtain eruptions from Enceladus' south-polar terrain

Science.gov (United States)

Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R.; Berkson, Emily E.; Platts, Symeon S.

2015-05-01

Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called `tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the surrounding terrain. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work examined those newer data sets and used triangulation of discrete jets to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions.

Effect of light energy on peroxide tooth bleaching.

Science.gov (United States)

Luk, Karen; Tam, Laura; Hubert, Manfred

2004-02-01

Light-activated bleaching is a method of tooth whitening. The authors conducted a study to compare the whitening effects and tooth temperature changes induced by various combinations of peroxide bleaches and light sources. The authors randomly assigned 250 extracted human teeth halves into experimental groups (n = 10). A placebo gel (control), a 35 percent hydrogen peroxide or a 10 percent carbamide peroxide bleach was placed on the tooth surface and was irradiated with no light (control); a halogen curing light; an infrared, or IR, light; an argon laser; or a carbon dioxide, or CO2, laser. Color changes were evaluated immediately, one day and one week after treatment using a value-oriented shade guide and an electronic dental color analyzer. The outer enamel and inner dentin surface temperatures were monitored before and immediately after each 30-second application of light using a thermocouple thermometer. Color and temperature changes were significantly affected by an interaction of the bleach and light variables. The application of lights significantly improved the whitening efficacy of some bleach materials, but it caused significant temperature increases in the outer and inner tooth surfaces. The IR and CO2 laser lights caused the highest tooth temperature increases. Dentists performing an in-office bleaching technique with the use of an additional light source to accelerate tooth whitening should consider the specific bleaching agent being used, as well as the potential risks of heating teeth. A specific combination of bleach and light that demonstrates good color change and little temperature rise should be selected for in-office tooth bleaching.

1984 Mauna Loa eruption and planetary geolgoy

International Nuclear Information System (INIS)

Moore, H.J.

1987-01-01

In planetary geology, lava flows on the Moon and Mars are commonly treated as relatively simple systems. Some of the complexities of actual lava flows are illustrated using the main flow system of the 1984 Mauna Loa eruption. The outline, brief narrative, and results given are based on a number of sources. The implications of the results to planetary geology are clear. Volume flow rates during an eruption depend, in part, on the volatile content of the lava. These differ from the volume flow rates calculated from post eruption flow dimensions and the duration of the eruption and from those using models that assume a constant density. Mass flow rates might be more appropriate because the masses of volatiles in lavas are usually small, but variable and sometimes unknown densities impose severe restrictions on mass estimates

Episode 49 of the Pu'u 'Ō'ō-Kūpaianaha eruption of Kilauea volcano-breakdown of a steady-state eruptive era

Science.gov (United States)

Mangan, M.T.; Heliker, C.C.; Mattox, T.N.; Kauahikaua, J.P.; Helz, R.T.

1995-01-01

The Pu'u 'O'o-Kupaianaha eruption (1983-present) is the longest lived rift eruption of either Kilauea or neighboring Mauna Loa in recorded history. The initial fissure opening in January 1983 was followed by three years of episodic fire fountaining at the Pu'u 'O'o vent on Kilauea's east rift zone ∼19km from the summit (episodes 4–47). These spectacular events gave way in July 1986 to five and a half years of near-continuous, low-level effusion from the Kupaianaha vent, ∼ 3km to the cast (episode 48). A 49th episode began in November 1991 with the opening of a new fissure between Pu'u 'O'o and Kupaianaha. This three week long outburst heralded an era of more erratic eruptive behavior characterized by the shut down of Kupaianaha in February 1992 and subsequent intermittent eruption from vents on the west flank of Pu'u 'O'o (episodes 50 and 51). The events occurring over this period are due to progressive shrinkage of the rift-zone reservoir beneath the eruption site, and had limited impact on eruption temperatures and lava composition.

Advances and perspectives in tooth tissue engineering.

Science.gov (United States)

Monteiro, Nelson; Yelick, Pamela C

2017-09-01

Bio-engineered teeth that can grow and remodel in a manner similar to that of natural teeth have the potential to serve as permanent replacements to the currently used prosthetic teeth, such as dental implants. A major challenge in designing functional bio-engineered teeth is to mimic both the structural and anisotropic mechanical characteristics of the native tooth. Therefore, the field of dental and whole tooth regeneration has advanced towards the molecular and nanoscale design of bio-active, biomimetic systems, using biomaterials, drug delivery systems and stem cells. The focus of this review is to discuss recent advances in tooth tissue engineering, using biomimetic scaffolds that provide proper architectural cues, exhibit the capacity to support dental stem cell proliferation and differentiation and sequester and release bio-active agents, such as growth factors and nucleic acids, in a spatiotemporal controlled manner. Although many in vitro and in vivo studies on tooth regeneration appear promising, before tooth tissue engineering becomes a reality for humans, additional research is needed to perfect methods that use adult human dental stem cells, as opposed to embryonic dental stem cells, and to devise the means to generate bio-engineered teeth of predetermined size and shape. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Volcanic eruption plumes on Io

International Nuclear Information System (INIS)

Strom, R.G.; Terrile, R.J.; Masursky, H.; Hansen, C.

1979-01-01

The detection of an umbrella-shaped plume extending about 280 km above the bright limb of Io was one of the most important discoveries made during the Voyager 1 encounter with the jovian system. This discovery proves that Io is volcanically active at present, and the number and magnitude of these eruptions indicate that Io is the most volcanically active body so far discovered in the Solar System. Preliminary analyses of these eruptive plumes are presented. (U.K.)

Russian eruption warning systems for aviation

Science.gov (United States)

Neal, C.; Girina, O.; Senyukov, S.; Rybin, A.; Osiensky, J.; Izbekov, P.; Ferguson, G.

2009-01-01

More than 65 potentially active volcanoes on the Kamchatka Peninsula and the Kurile Islands pose a substantial threat to aircraft on the Northern Pacific (NOPAC), Russian Trans-East (RTE), and Pacific Organized Track System (PACOTS) air routes. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors and reports on volcanic hazards to aviation for Kamchatka and the north Kuriles. KVERT scientists utilize real-time seismic data, daily satellite views of the region, real-time video, and pilot and field reports of activity to track and alert the aviation industry of hazardous activity. Most Kurile Island volcanoes are monitored by the Sakhalin Volcanic Eruption Response Team (SVERT) based in Yuzhno-Sakhalinsk. SVERT uses daily moderate resolution imaging spectroradiometer (MODIS) satellite images to look for volcanic activity along this 1,250-km chain of islands. Neither operation is staffed 24 h per day. In addition, the vast majority of Russian volcanoes are not monitored seismically in real-time. Other challenges include multiple time-zones and language differences that hamper communication among volcanologists and meteorologists in the US, Japan, and Russia who share the responsibility to issue official warnings. Rapid, consistent verification of explosive eruptions and determination of cloud heights remain significant technical challenges. Despite these difficulties, in more than a decade of frequent eruptive activity in Kamchatka and the northern Kuriles, no damaging encounters with volcanic ash from Russian eruptions have been recorded. ?? Springer Science+Business Media B.V. 2009.

Autotransplantation donor tooth site harvesting using piezosurgery.

Science.gov (United States)

Ylikontiola, Leena P; Sándor, George K

2016-01-01

The harvesting of a tooth as a candidate for tooth autotransplantation requires that the delicate dental tissues around the tooth be minimally traumatized. This is especially so for the periradicular tissues of the tooth root and the follicular tissues surrounding the crown. The aim of this report is to describe the use of piezosurgery as an attempt at morbidity reduction in the harvesting of teeth for autotransplantation. A piezosurgical handpiece and its selection of tips were easily adapted to allow the harvesting and delivery of teeth for autotransplantation purposes. Twenty premolar teeth were harvested using a piezosurgical device. The harvested teeth were subsequently successfully autotransplanted. All twenty teeth healed in a satisfactory manner without excessive mobility or ankyloses. Piezosurgery avoids some of the traumatic aspects of harvesting teeth and removing bone which are associated with thermal damage from the use of conventional rotary instruments or saws. Piezosurgery can be adapted to facilitate the predictable harvesting of teeth for autotransplantation purposes.

CONTRACTING AND ERUPTING COMPONENTS OF SIGMOIDAL ACTIVE REGIONS

International Nuclear Information System (INIS)

Liu Rui; Wang Yuming; Liu Chang; Wang Haimin; Török, Tibor

2012-01-01

It has recently been noted that solar eruptions can be associated with the contraction of coronal loops that are not involved in magnetic reconnection processes. In this paper, we investigate five coronal eruptions originating from four sigmoidal active regions, using high-cadence, high-resolution narrowband EUV images obtained by the Solar Dynamic Observatory (SDO). The magnitudes of the flares associated with the eruptions range from GOES class B to class X. Owing to the high-sensitivity and broad temperature coverage of the Atmospheric Imaging Assembly (AIA) on board SDO, we are able to identify both the contracting and erupting components of the eruptions: the former is observed in cold AIA channels as the contracting coronal loops overlying the elbows of the sigmoid, and the latter is preferentially observed in warm/hot AIA channels as an expanding bubble originating from the center of the sigmoid. The initiation of eruption always precedes the contraction, and in the energetically mild events (B- and C-flares), it also precedes the increase in GOES soft X-ray fluxes. In the more energetic events, the eruption is simultaneous with the impulsive phase of the nonthermal hard X-ray emission. These observations confirm that loop contraction is an integrated process in eruptions with partially opened arcades. The consequence of contraction is a new equilibrium with reduced magnetic energy, as the contracting loops never regain their original positions. The contracting process is a direct consequence of flare energy release, as evidenced by the strong correlation of the maximal contracting speed, and strong anti-correlation of the time delay of contraction relative to expansion, with the peak soft X-ray flux. This is also implied by the relationship between contraction and expansion, i.e., their timing and speed.

Introduction to the 2012-2013 Tolbachik eruption special issue

Science.gov (United States)

Edwards, Benjamin R.; Belousov, Alexander; Belousova, Marina; Volynets, Anna

2015-12-01

The Tolbachik volcanic complex in central Kamchatka holds a special place in global volcanological studies. It is one of 4 areas of extensive historic volcanic activity in the northern part of the Central Kamchatka Depression (the others being Klyuchevskoy, Bezymianny, Shiveluch), and is part of the Klyuchevskoy volcanic group, which is one of the most active areas of volcanism on Earth. Tolbachik is especially well-known due largely to the massive 1975-1976 eruption that became known as the Great Tolbachik Fissure eruption (GTFE; Fedotov, 1983; Fedotov et al., 1984). This was one of the first eruptions in Russia to be predicted based on precursory seismic activity, based on M5 earthquakes approximately one week before the eruption started, and was intensively studied during its course by a large number of Russian scientists. A summary of those studies was published, first in Russian and then in English, and it became widely read for many reasons. One in particular is that the eruption was somewhat unusual for a subduction zone setting; although many subduction zone stratovolcanoes have associated basaltic tephra cone-lava fields, this was the first such Hawaiian-style eruption to be widely observed. After the end of the eruption in 1976, the complex showed no signs of activity until 27 November 2012, when increased seismic activity was registered by the Kamchatka Branch of the Russian Geophysical Survey and a red glow from the eruption site was first noticed through the snowstorm haze. This prompted them, and then the Kamchatka Volcanic Emergency Response Team (KVERT) to issue an alert that activity was coming from the south flank of Plosky Tolbachik volcano, the younger of two volcanic edifices (the older is Ostry Tolbachik) that together make up the bulk of the complex along with tephra cone-lava fields that lie along a NE-SW fissure zone that transects Plosky Tolbachik. The new eruption lasted for more than 250 days and, like the 1975-1976 eruption, was

Innovative Design and Performance Evaluation of Bionic Imprinting Toothed Wheel.

Science.gov (United States)

Zhang, Zhihong; Wang, Xiaoyang; Tong, Jin; Stephen, Carr

2018-01-01

A highly efficient soil-burrowing dung beetle possesses an intricate outer contour curve on its foreleg end-tooth. This study was carried out based on evidence that this special outer contour curve has the potential of reducing soil penetration resistance and could enhance soil-burrowing efficiency. A toothed wheel is a typical agricultural implement for soil imprinting, to increase its working efficiency; the approach of the bionic geometrical structure was utilized to optimize the innovative shape of imprinting toothed wheel. Characteristics in the dung beetle's foreleg end-tooth were extracted and studied by the edge detection technique. Then, this special outer contour curve was modeled by a nine-order polynomial function and used for the innovative design of imprinting the tooth's cutting edge. Both the conventional and bionic teeth were manufactured, and traction tests in a soil bin were conducted. Taking required draft force and volume of imprinted microbasin as the evaluating indexes, operating efficiency and quality of different toothed wheels were compared and investigated. Results indicate that compared with the conventional toothed wheel, a bionic toothed wheel possesses a better forward resistance reduction property against soil and, meanwhile, can enhance the quality of soil imprinting by increasing the volume of the created micro-basin.

SYMPATHETIC FILAMENT ERUPTIONS FROM A BIPOLAR HELMET STREAMER IN THE SUN

International Nuclear Information System (INIS)

Yang Jiayan; Jiang Yunchun; Zheng Ruisheng; Bi Yi; Hong Junchao; Yang Bo

2012-01-01

On 2005 August 5, two solar filaments erupted successively from different confined arcades underlying a common overarching multiple-arcade bipolar helmet streamer. We present detailed observations of these two events and identify them as sympathetic filament eruptions. The first (F1) is a small active-region filament located near the outskirts of the streamer arcade. It underwent a nonradial eruption, initially moving in the interior of the streamer arcade and resulting in an over-and-out coronal mass ejection. The second filament (F2), a larger quiescent one far away from F1, was clearly disturbed during the F1 eruption. It then underwent a very slow eruption and finally disappeared completely and permanently. Because two belt-shaped diffuse dimmings formed along the footprints of the streamer arcade in the first eruption and persisted throughout the complete disappearance of F2, the eruption series are interpreted as sympathetic: the simple expansion of the common streamer arcade forced by the F1 eruption weakened magnetic flux overlying F2 and thus led to its slow eruption, with the dimming formation indicating their physical connection. Our observations suggest that multiple-arcade bipolar helmet-streamer configurations are appropriate to producing sympathetic eruptions. Combined with the recent observations of unipolar-streamer sympathetic events, it appears that a multiple-arcade unipolar or bipolar helmet streamer can serve as a common magnetic configuration for sympathetic eruptions.

Tooth brushing among 11- to 15-year-olds in Denmark

DEFF Research Database (Denmark)

Bast, L. S.; Holstein, B. E.; Nordahl, Helene

2015-01-01

brushing. Results: 10,607 respondents: a response rate of 88.3%. Boys of lower social class had higher odds ratio (OR) of infrequent tooth brushing than girls: 1.98 (95% confidence interval 1.62-2.41) vs 1.80 (1.53-2.24). Immigrants and descendants had higher odds compared to adolescents of Danish origin......Objective: Regular tooth brushing in adolescence predicts stable tooth brushing habits later in life. Differences in tooth brushing habits by ethnic background and socioeconomic position have been suggested. We investigated migration status and social class in relation to infrequent tooth brushing...... both separately and combined. Methods: The study population was 11-15 year-olds chosen from a clustered random sample of schools. Univariate and multivariate logistic regression analyses estimated the separate and combined effects of migration status and social class on less than twice daily tooth...

Tooth color: effects on judgments of attractiveness and age.

Science.gov (United States)

Grosofsky, Alexis; Adkins, Sarah; Bastholm, Robert; Meyer, Leif; Krueger, Lisa; Meyer, Joshua; Torma, Peter

2003-02-01

Tooth whitening has become a very popular procedure. Advertisements for whitening products imply that whiter teeth are more attractive than yellower teeth. We tested this idea empirically by manipulating the tooth color of pictures of male and female targets. Participants' ratings of attractiveness were not influenced by tooth color. Exp. 2 yielded a negative correlation between attractiveness and age ratings: targets judged to be older were rated as less attractive. Unless whiter teeth help in some other way, e.g., improved self-esteem or confidence, it seems that tooth whitening procedures or products are not associated with increased attractiveness to others.