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1.
Braz. j. oral sci ; 21: e222812, jan.-dez. 2022. tab
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1348712

RESUMO

Aim: To evaluate the influence of the parameters L* a* b* on the variation of the color of bovine tooth enamel submitted to artificial darkening, after simulated brushing, with whitening toothpastes containing blue covarine. Methods: To undertake this study in vitro, 60 specimens (SP) were divided into 6 groups (n=10): control group (CGwater) and 5 test groups (GT1-Colgate Total 12, GT2-Oral-B 3D White Perfection, GT3- Colgate Luminous Instant White, GT4-CloseUp White Diamond Attraction, GT5-Sorriso Xtreme White). The specimens were darkened with coffee and submitted to simulated brushing for 6, 12, and 24 months. The alteration in the color was evaluated using CIELAB parameters and the ΔL, Δa, Δb and ΔE were calculated. The data was analyzed through generalized linear models using the R program and considering a level of significance of 5%. Results: The parameters L*, a* and the ΔL, Δa obtained better results in the test group than in the control group. There were no statistical differences between CG and the test groups for the evaluation of the b* parameter. In the evaluation of the Δb, the GT3 differed statistically from the CG. In relation to the ΔE, all the group tests showed a variation in color statistically greater than that of the CG and the GT4 showed the greatest variation, not differing from the GT3 during the periods studied. Conclusion: The mechanical and optical whitening agents positively influenced the values L*a* and b*, as well as in its variations and in the ΔE. It is important to emphasize, however, that to analyze tooth whitening it is necessary to evaluate their parameters together


Assuntos
Dente , Cremes Dentais , Cor , Clareadores
2.
Nature ; 605(7909): 196, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35505105
3.
Sci Rep ; 12(1): 6045, 2022 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-35501323

RESUMO

Apex predators play an important role in the top-down regulation of ecological communities. Their hunting and feeding behaviors influence, respectively, prey demography and the availability of resources to other consumers. Among the most iconic-and enigmatic-terrestrial predators of the late Cenozoic are the Machairodontinae, a diverse group of big cats whose hypertrophied upper canines have earned them the moniker "sabertooths." Many aspects of these animals' paleobiology, especially their prey preferences and carcass consumption behavior, remain unsettled. While skeletal anatomy, dental morphology and wear, and isotopic profiles provide important insights, the most direct way to resolve these issues is through the fossil remains of sabertooth prey. Here, we report on a taphonomic analysis of an early Pleistocene faunal assemblage from Haile 21A (Florida, USA) that preserves feeding damage from the lion-sized sabertooth Xenosmilus hodsonae. Patterns of tooth-marking and bone damage indicate that Xenosmilus fully defleshed the carcasses of their prey and even engaged in some minor bone consumption. This has important implications for Pleistocene carnivoran guild dynamics, including the carcass foraging behavior of the first stone-tool-using hominins.


Assuntos
Hominidae , Leões , Dente , Animais , Osso e Ossos , Fósseis , Hominidae/fisiologia
4.
Nat Commun ; 13(1): 2390, 2022 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-35501345

RESUMO

Innovations relating to the consumption of hard prey are implicated in ecological shifts in marine ecosystems as early as the mid-Paleozoic. Lungfishes represent the first and longest-ranging lineage of durophagous vertebrates, but how and when the various feeding specializations of this group arose remain unclear. Two exceptionally preserved fossils of the Early Devonian lobe-finned fish Youngolepis reveal the origin of the specialized lungfish feeding mechanism. Youngolepis has a radically restructured palate, reorienting jaw muscles for optimal force transition, coupled with radiating entopterygoid tooth rows like those of lungfish toothplates. This triturating surface occurs in conjunction with marginal dentition and blunt coronoid fangs, suggesting a role in crushing rather than piercing prey. Bayesian tip-dating analyses incorporating these morphological data indicate that the complete suite of lungfish feeding specializations may have arisen in as little as 7 million years, representing one of the most striking episodes of innovation during the initial evolutionary radiations of bony fishes.


Assuntos
Ecossistema , Dente , Animais , Teorema de Bayes , Peixes/anatomia & histologia , Fósseis
5.
Compend Contin Educ Dent ; 43(5): E9-eE12, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35523317

RESUMO

Rubber dams are frequently used to enable clinicians to achieve better visualization and isolation for dental procedures. Growing in popularity thanks in part to an increasing number of techniques facilitating their placement, rubber dams are able to be used for myriad restorative procedures, including crown and veneer preparation and cementation. An effect of rubber dam use is reduction of saliva, which causes temporary dehydration of the isolated teeth. In turn, this dehydration affects shade matching, an important aspect of esthetic outcomes. The purpose of this study was to determine the extent that shade is altered from baseline due to dehydration from rubber dam use during restorative procedures, and, furthermore, to determine the length of time required for teeth to rehydrate back to their baseline shade.


Assuntos
Desidratação , Dente , Coroas , Estética Dentária , Humanos , Diques de Borracha
6.
Sci Rep ; 12(1): 7499, 2022 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-35525838

RESUMO

The molluscan phylum is the second specious animal group with its taxa feeding on a variety of food sources. This is enabled by the radula, a chitinous membrane with embedded teeth, one important autapomorphy. Between species, radulae can vary in their morphology, mechanical, and chemical properties. With regard to chemical composition, some taxa (Polyplacophora and Patellogastropoda) were studied extensively in the past decades, due to their specificity to incorporate high proportions of iron, calcium, and silicon. There is, however, a huge lack of knowledge about radular composition in other taxa. The work presented aims at shedding light on the chemistry by performing energy-dispersive X-ray spectroscopy analyses on 24 molluscan species, thereof two Polyplacophora, two Cephalopoda, and 20 Gastropoda, which was never done before in such a comprehensiveness. The elements and their proportions were documented for 1448 individual, mature teeth and hypotheses about potential biomineralization types were proposed. The presented work additionally comprises a detailed record on past studies about the chemical composition of molluscan teeth, which is an important basis for further investigation of the radular chemistry. The found disparity in elements detected, in their distribution and proportions highlights the diversity of evolutionary solutions, as it depicts multiple biomineralization types present within Mollusca.


Assuntos
Gastrópodes , Hepatófitas , Poliplacóforos , Dente , Animais , Evolução Biológica , Gastrópodes/anatomia & histologia , Moluscos/anatomia & histologia , Dente/anatomia & histologia
7.
J Mech Behav Biomed Mater ; 130: 105212, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35381518

RESUMO

OBJECTIVES: Enamel wear is a common occurrence that may lead to tooth failure. Beyond reducing enamel thickness, wear exposes different regions of enamel microstructure to various types of stresses. This work was aimed at elucidating the effect of enamel wear on enamel morphology and tooth resilience in human molar teeth undergoing large-scale contact. METHODS: Intact/polished molar cusps were indented with a hard disk/ball. The unloaded specimens were sectioned longitudinally or transversely, and the damage examined by optical and scanning electron microscopy. The onset of cracks at the dentin horn apex was determined by a FEM stress analysis that modeled a cusp as truncated, conical enamel shell supported by dentin. RESULTS: The damage consisted of radial and cylindrical cracks growing under the contact, sparsely distributed radial cracks in the enamel shell region, and cracking from tufts at the dentin horn apex (TA cracks). The damage under the contact circle exhibited shear deformation zones. These zones helped relieve contact stresses, absorb energy, contain damage, and solicit cylindrical cracks in order to avoid growth of wear-sensitive cone cracks. Enamel tufts provided stress shielding while Hunter-Schreger Bands helped maintain this benefit by enforcing a collaborative cracking. The TA cracks were deemed a primary cause for tooth failure. The FEA predicted well the onset of these cracks. Making use of in vivo enamel wear data, the analysis showed that cusp failure might routinely occur at old age. SIGNIFICANCE: The results provided new information on the response of the interior part of enamel to contact loading. This included the resistant effects of the waviness of enamel rods, interrods and tufts. The unique microstructure of enamel gave rise to shear bands under the contact circle that helped relieve contact stresses, absorb energy and contain damage. Enamel interrods solicited cylindrical cracking in order to avoid the wear-sensitive cone cracks. The onset of cracks at the dentin horn apex (TA cracks) was deemed critical to a tooth survival. The FEA showed that this cracking mode might routinely occur at old age due to natural enamel wear. Finally, the occlusal force needed to initiate the TA cracks in intact cusps can help explain the natural design logic involving the maximum bite force of hominid species.


Assuntos
Dente , Força de Mordida , Humanos , Microscopia Eletrônica de Varredura , Dente Molar/fisiologia
8.
J Mech Behav Biomed Mater ; 130: 105221, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35405521

RESUMO

Human tooth enamel is composed of enamel rods and surrounding inter-rod enamel. As the fundamental block of enamel, hydroxyapatite (HAP) nanofibers are mostly longitudinally aligned in the rods but inclined in the inter-rod enamel. The surface hardening of enamel by occlusal loading is reportedly a result of hydroxyapatite nanofiber fragmentation and rearrangement and plays an important role in the anti-wear performance of enamel, but little is known about the effect of HAP nanofiber orientation on enamel surface hardening. In this study, the occlusal loading-induced surface hardening behaviors of enamel at different zones (rod and inter-rod) and different orientations (occlusal and axial) were investigated in vitro using impact treatment and a nanoindentation technique, aiming to reveal the effect of nanofiber orientation on enamel surface hardening. It was found that surface hardening by occlusal loading occurs in the rod and inter-rod areas, but the former shows a greater hardening degree than the latter, leading to an increase in the mechanical heterogeneity of enamel surface. Under the same loading condition, the HAP nanofibers in the inter-rod enamel are more likely to tilt into transverse nanofibers than those in the rods. Compared with longitudinal nanofibers, transverse nanofibers fragment into more transverse crystal particles, but the transverse particles impair the compactness of the hardening layer and decrease its hardening degree. In sum, inherent non-uniform nanofiber orientation endows the enamel with the ability to undergo heterogeneous surface hardening upon occlusal loading, which is critical for providing and maintaining its surface mechanical heterogeneity. These findings extend the understanding of the relationship between microstructure and mechanical properties of dental enamel and provide valuable insights into the bionic design of engineering materials.


Assuntos
Nanofibras , Dente , Esmalte Dentário , Durapatita/química , Humanos
9.
Sci Rep ; 12(1): 6246, 2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35428796

RESUMO

To overcome the limitations of the conventional vacuum thermoforming manufacturing method, direct 3D printing of clear aligners has been developed. The present study investigated the thermo-mechanical and viscoelastic properties of a photocurable resin TC-85, which is a new material for the direct 3D printed clear aligners, comparing to a conventional thermoplastic material polyethylene terephthalate glycol. Dynamic mechanical analysis was performed to analyse the mechanical behaviours of the two materials at 37 °C and 80 °C, respectively. Furthermore, the shape memory property of the two materials was evaluated using a U-shape bending test, and the shape recovery ratio for 60 min at 37 °C was calculated. The results indicate that TC-85 can constantly apply a light force to the teeth when used for the 3D printed clear aligners, owing to its flexibility and viscoelastic properties. In addition, it is expected that the force decay induced by repeated insertion of the clear aligners will be reduced and a constant orthodontic force will be maintained. Furthermore, its geometric stability at high temperatures and the shape memory properties provide advantages for the clinical application.


Assuntos
Aparelhos Ortodônticos Removíveis , Dente , Fenômenos Mecânicos , Impressão Tridimensional
10.
J Indian Soc Pedod Prev Dent ; 40(1): 30-33, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35439880

RESUMO

Background: Dental caries begins with the initiation of demineralization which is a reversible process. Diet, especially intake of sugar, is an important aetiological factor for demineralization of enamel which eventually leads to caries. Aim: This study aims to understand the quantitative relationship between sugar consumption and mineralization by finding out the change in mineralization of teeth as a result of the change in the sugar score. Settings and Design: This interventional study was done among 119 teeth of 19 subjects who were between the ages of 13-15 years in Hubli city. Materials and Methods: Sugar score was calculated from a 5-day diet history of the subjects and a DIAGNOdent pen was used to indicate the mineralization value of the teeth before the intervention. Diet counseling was given as an intervention after which sugar score and DIAGNOdent scores were measured again after 14 days and compared with the baseline values. Statistical Analysis: Descriptive statistics and a linear regression analysis was done to determine the relationship between the variables. Results: Sugar score and DIAGNOdent score after 14 days were found to have reduced significantly by 41.6% and 20.3% respectively from the baseline values. The Linear Regression indicated that a reduction of sugar score by 5 resulted in a decrease of DIAGNOdent score by 0.16. Conclusion: The findings of the present study suggest that the modification of sugar consumption brought about a significant improvement in the mineralization of the demineralized teeth thus making diet counseling an effective preventive strategy for caries prevention.


Assuntos
Cárie Dentária , Dente , Adolescente , Cárie Dentária/epidemiologia , Cárie Dentária/prevenção & controle , Açúcares da Dieta/efeitos adversos , Fluorescência , Humanos , Projetos Piloto , Açúcares
11.
J Indian Soc Pedod Prev Dent ; 40(1): 43-47, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35439882

RESUMO

Age is one of the essential factors, which plays an important role in every aspect of life. Age is estimated on the basis of chronological age, bone age, dental age, mental age and others. This study represents the objective of an ideal age estimation technique to arrive at an age as close to the chronological age as possible. Aim: The aim of this comparative study was to estimate the dental age using Willems method by assessing the developmental stages of left seven permanent mandibular teeth in 7-14 years of age groups with the help of digital orthopantomogram and comparing it with Demirjian's method to conclude which method was more appropriate and better in Indian population of Uttarakhand region. Materials and Methods: A total of 100 digital orthopantomogram films of patients in the age group of 7-14 years was collected over the study period of 3 years from July 2014 to January 2017 and was equally distributed by convenience sampling. Group I included 50 boys and Group II included 50 girls aging 7-14 years of age (as permanent 7 teeth in the 3rd quadrant were to be assessed and scored according to the Demirjian's table, the 7-14 age group was selected). The date of birth of the subject was documented against their allocated identification number. Dental age according to Willem's method was calculated using Willem's table and Demirjian and Goldstein's table scores were used to calculate dental age by Demirjian's method. Results: Willems method was more accurate and better than Demirjian's method as it showed less mean percentage error, i.e., 0.34% as compared to 15.94% obtained from Demirjian's method in Group II and 2.19% as compared to 8.05% obtained from Demirjian's method in Group I. Conclusion: The results suggested that Willems method of dental age estimation was an effective method of age estimation and was better and more accurate than Demirjian's method.


Assuntos
Determinação da Idade pelos Dentes , Dente , Adolescente , Determinação da Idade pelos Dentes/métodos , Criança , Dentição Permanente , Feminino , Humanos , Masculino , Mandíbula/diagnóstico por imagem , Radiografia Panorâmica
12.
ScientificWorldJournal ; 2022: 8415705, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35450417

RESUMO

Dental caries detection, in the past, has been a challenging task given the amount of information got from various radiographic images. Several methods have been introduced to improve the quality of images for faster caries detection. Deep learning has become the methodology of choice when it comes to analysis of medical images. This survey gives an in-depth look into the use of deep learning for object detection, segmentation, and classification. It further looks into literature on segmentation and detection methods of dental images through deep learning. From the literature studied, we found out that methods were grouped according to the type of dental caries (proximal, enamel), type of X-ray images used (extraoral, intraoral), and segmentation method (threshold-based, cluster-based, boundary-based, and region-based). From the works reviewed, the main focus has been found to be on threshold-based segmentation methods. Most of the reviewed papers have preferred the use of intraoral X-ray images over extraoral X-ray images to perform segmentation on dental images of already isolated parts of the teeth. This paper presents an in-depth analysis of recent research in deep learning for dental caries segmentation and detection. It involves discussing the methods and algorithms used in segmenting and detecting dental caries. It also discusses various existing models used and how they compare with each other in terms of system performance and evaluation. We also discuss the limitations of these methods, as well as future perspectives on how to improve their performance.


Assuntos
Cárie Dentária , Dente , Algoritmos , Cárie Dentária/diagnóstico por imagem , Humanos
14.
Sci Rep ; 12(1): 6139, 2022 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-35414687

RESUMO

This study evaluated dental caries detection ability between the Qraycam and Qraypen on the same dental caries lesions. A total of 178teeth from 61patients were imaged using Qraypen C®(QC) and Qraycam Pro®(QP) devices and evaluated using analysis software (QA2). Occlusal, secondary, and proximal dental caries were evaluated and scored according to International Caries Detection and Assessment System(ICDAS II) and X-ray criteria. Bland-Altman plots were used to compare quantitative light-induced fluorescence(QLF) parameters obtained from the different QLF devices. Sensitivity, specificity, and area under the receiver operating characteristic curve(AUROC) were calculated. The ΔFaver. of the QLF-parameters showed that the mean difference between the two different QLF devices was close to zero and that the ± 5 error value was included in the mean ± 1.96SD range for the detection of dental caries. The accuracies for diagnosing occlusal dental caries were 0.83-0.96 and 0.81-0.82 and the accuracies for diagnosing proximal dental caries were 0.52-0.62 and 0.52-0.71 for the QC and QP devices, respectively. In conclusion, the ΔFaver. obtained from the QP showed diagnostic value mainly for screening of demineralized teeth. For teeth selected through screening, the depth of the lesion must be precisely evaluated using additional QP and radiographic imaging.


Assuntos
Cárie Dentária , Fluorescência Quantitativa Induzida por Luz , Dente , Cárie Dentária/diagnóstico por imagem , Cárie Dentária/patologia , Fluorescência , Humanos , Programas de Rastreamento , Curva ROC , Sensibilidade e Especificidade , Dente/patologia
15.
Georgian Med News ; (324): 204-210, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35417886

RESUMO

The role of trace elements (microelements) in maintaining oral health has not been fully investigated and still remains the subject of research and discussion. Some trace elements contribute to the development of caries, while others, on the contrary, prevent formation of this process and accelerate the restoration of dental hard tissues. Penetration of trace elements into human dental structures via saliva, food, water and other routes contributes to the formation of carious diseases, or, conversely, its cessation and/or regression. Analyzing the studies allowed us to conclude that there is very scarce information available in the literature about the layered, zonal distribution of "vital" trace elements in healthy (intact) teeth dentin and enamel. However, to study the distribution of caries-static elements (Ca, F, P) on the enamel surface as well as in para-pulpal dentin is of great importance as well. It was aimed to identify trace elements in human teeth structures (enamel, dentin and cementum), as well as to determine their localization and concentration. To reach this objective, X-ray spectral analysis on 6 intact, extracted teeth has been performed by Scanning Electron Microscopy (SEM). Identification of trace elements was performed on the 6 sites/locations of these teeth: enamel surface layer, enamel thickness, enamel-dentin border, parapulpal dentin, root dentin, and cementum. As a result, it has been found that the distribution of essential trace elements in dental hard tissues is uneven, while such an important element in maintaining healthy teeth as Fluorine has been found in only minimal concentrations in hard tissues.


Assuntos
Cárie Dentária , Dente , Oligoelementos , Cárie Dentária/diagnóstico por imagem , Dentina/química , Dentina/diagnóstico por imagem , Dentina/ultraestrutura , Elétrons , Humanos , Dente/química , Dente/diagnóstico por imagem , Oligoelementos/análise , Raios X
16.
Stomatologiia (Mosk) ; 101(2): 93-99, 2022.
Artigo em Russo | MEDLINE | ID: mdl-35362710

RESUMO

Due to the high mobility and variability of bone structures and soft tissues surrounding the upper respiratory tract, the exact boundaries for measuring and normalizing the size of the respiratory tract have not yet been determined. Studies have determined the relationship between the narrowing of the upper jaw and a decrease in the transverse dimensions of the airways, as well as a positive effect in changing the size of the airways after orthodontic treatment and/or orthognathic surgery. Nevertheless, the results of research in this area may differ greatly from different specialists, which indicates that the topic is poorly studied and it is necessary to continue and expand the range of scientific works to assess the state of the upper respiratory tract and their relationship with the orthodontic status.


Assuntos
Procedimentos Cirúrgicos Ortognáticos , Dente , Humanos , Maxila , Nariz
17.
West Afr J Med ; 39(3): 299-305, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35381844

RESUMO

BACKGROUND: Tooth variation within populations is important for anthropologists and dentists. The objective was to compare crown dimensions among three Nigerian ethnic populations. MATERIALS AND METHODS: An electronic caliper was used to measure mesiodistal and buccolingual tooth width of maxillary and mandibular permanent teeth except third molars from study casts of 132 Nigerian subjects with a mean age of 19.03 ± 4.27 years. The Hausa sample was 50 (37.9%) subjects (25 males and 25 females); the Yoruba population was 50 (37.9%) subjects (15 males and 35 females) and the Igbo sample was 32 (24.2%) subjects (16 males and 16 females). Single teeth and sums of groups of teeth were compared between males and females within and among the three populations using analysis of variance. RESULTS: The findings indicated that (1) differences between antimeres are of small magnitude and of no statistical significance; (2) Significant gender differences in tooth dimension was observed with Yoruba and Hausa males having significantly larger teeth but a significant gender difference was only observed for mesiodistal width of the maxillary second molars in the Igbo population; (3) there is a greater similarity among Yoruba and Igbo subjects with differences from their Hausa counterparts with a magnitude considered statistically and clinically significant. CONCLUSION: The crown dimensions of Hausa males and females were significantly smaller than their Yoruba and Igbo counterparts. There were similarities in crown dimensions between Yoruba males and females and their Igbo counterparts. Sexual dimorphism of crown size was observed in the three ethnic groups.


CONTEXTE: La variation incisive dans une population est tres important chez les anthropologues et les dentiste. L'objective de cet oeuvre c'est de comparer les dimensions des couronnes parmi les trios populations ethniques du Nigeria. MATERIEL ET METHODES: Une coulisse electronique a ete utilise pour measure la mesiodistale et le largeur des dents buccolingue de maxilaire et mandibulaire des dents permanent excepte le 3eme molaire, d'apres l'etude sur 132 Nigerians avec un age moyen de 19.03 ± 4.27 ans.L'echantillon des Haoussas etaient 50 (37.9%) sujets (25 males et 25 femelles); la population des Yoruobas etaient 50 (37.9%) sujets (15 males et 5 femmes) et l'echantillon des Igbos etaient 32 (24.2%) sujets (16 males et 16 femmes) des dents individuels et le total de groupe de dents a ete compare entre les hommes et les femmes des trois populations utilisant l' analyse de variance. RESULTATS: Le resultat a indique que (1) les differences entre les antimeres sont de peu magnitude et n'ont pas de signification statistique; (2) La signification de difference de gendre dans la dimension de dent a ete observe chez les males Yoruoba et les males Hauossa qui ont des dents plus large mais une difference de gendre significative a ete observe seulment pour le largeur mesiodistal du second molaire maxillaire dans la population des Igbos ; (3) il y a une grand similarite entre les sujets Yoruobas et Igbos en comparaison a leurs voisin Haoussa avec une magnitude considere statistiquement et cliniquement significative. CONCLUSION: Les dimensions des couronnes des dents de males et femmes Hauossa etaient plus petit en comparaison aux Yoruoba et Igbo . Il y avaient des similarities dans la dimension de couronne des males et femmes Yoruoba et les Igbo . Le dimorphisme sexual de la taille de couronne a ete observe dans les trios groupes ethniques. Most cle: La difference de gendre; l'Anatomie dentaire; Le Nigeria; La population genetique.


Assuntos
Dente , Adolescente , Adulto , Dentição Permanente , Feminino , Humanos , Masculino , Maxila , Nigéria , Dente/anatomia & histologia , Coroa do Dente , Adulto Jovem
18.
Sci Rep ; 12(1): 6172, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35418659

RESUMO

Odontodes, i.e., teeth and tooth-like structures, consist of a pulp cavity and dentin covered by a mineralized cap. These structures first appeared on the outer surface of vertebrate ancestors and were repeatedly lost and gained across vertebrate clades; yet, the underlying genetic mechanisms and trajectories of this recurrent evolution remain long-standing mysteries. Here, we established suckermouth armored catfish (Ancistrus sp.; Loricariidae), which have reacquired dermal odontodes (dermal denticles) all over most of their body surface, as an experimental model animal amenable to genetic manipulation for studying odontode development. Our histological analysis showed that suckermouth armored catfish develop dermal denticles through the previously defined odontode developmental stages. De novo transcriptomic profiling identified the conserved odontode genetic regulatory network (oGRN) as well as expression of paired like homeodomain 2 (pitx2), previously known as an early regulator of oGRN in teeth but not in other dermal odontodes, in developing dermal denticles. The early onset of pitx2 expression in cranial dermal denticle placodes implies its function as one of the inducing factors of the cranial dermal denticles. By comprehensively identifying the genetic program for dermal odontode development in suckermouth armored catfish, this work illuminates how dermal odontodes might have evolved and diverged in distinct teleost lineages via redeployment of oGRN.


Assuntos
Peixes-Gato , Calcificações da Polpa Dentária , Dente , Animais , Evolução Biológica , Peixes-Gato/genética , Redes Reguladoras de Genes , Dente/metabolismo
19.
Elife ; 112022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35441592

RESUMO

The dental system of ceratopsids is among the most specialized structure in Dinosauria by the presence of tooth batteries and high-angled wear surfaces. However, the origin of this unique dental system is poorly understood due to a lack of relevant knowledge in early-diverging ceratopsians. Here, we study the dental system of three earliest-diverging Chinese ceratopsians: Yinlong and Hualianceratops from the early Late Jurassic of Xinjiang and Chaoyangsaurus from the Late Jurassic of Liaoning Province. By micro-computed tomographic analyses, our study has revealed significant new information regarding the dental system, including no more than five replacement teeth in each jaw quadrant; at most one replacement tooth in each alveolus; nearly full resorption of the functional tooth root; and occlusion with low-angled, concave wear facets. Yinlong displays an increase in the number of maxillary alveoli and a decrease in the number of replacement teeth during ontogeny as well as the retention of functional tooth remnants in the largest individual. Chaoyangsaurus and Hualianceratops have slightly more replacement teeth than Yinlong. In general, early-diverging ceratopsians display a relatively slow tooth replacement rate and likely use gastroliths to triturate foodstuffs. The difference in dietary strategy might have influenced the tooth replacement pattern in later-diverging ceratopsians.


Assuntos
Dinossauros , Dente , Animais , Dieta , Dinossauros/anatomia & histologia , Fósseis , Odontogênese , Dente/diagnóstico por imagem
20.
Artigo em Inglês | MEDLINE | ID: mdl-35457428

RESUMO

Tooth shell technique (TST) using autologous dentine is possible with lateral ridge augmentation while avoiding a donor region. This study aimed to clarify whether the use of periodontally compromised teeth (PCT) leads to similar results compared to non-periodontally compromised teeth (NPCT). In this retrospective study, the dentin matrix of 41 patients (PCT: n = 19 with 29 implants; NPCT: n = 22, with 29 implants) was used for TST. All cases were re-examined. Outcome parameters were biological complications, horizontal hard tissue loss, osseointegration, and the integrity of the buccal lamella. Only in one case in the PCT group, a graft was lost. In three cases, minor complications were identified, including two cases of wound dehiscence and one case of inflammation with suppuration (PCT: n = 1, NPCT: n = 3). All implants, except the one with the severe complication, were osseointegrated and the integrity of the buccal bone lamella was preserved. Mean difference of the resorption of the crestal width and the buccal lamella did not differ statistically between the two groups. TST using PCT showed results comparable to those of NPCT in terms of complications and graft resorption. Processed dentin matrix from PCT can be used and applied with predictable results for bone grafting, utilizing TST.


Assuntos
Aumento do Rebordo Alveolar , Dente , Aumento do Rebordo Alveolar/métodos , Transplante Ósseo/métodos , Dentina , Humanos , Estudos Retrospectivos
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