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1.
J Vis Exp ; (206)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38738893

RESUMO

The mechanical property, microhardness, is evaluated in dental enamel, dentin, and bone in oral disease models, including dental fluorosis and periodontitis. Micro-CT (µCT) provides 3D imaging information (volume and mineral density) and scanning electron microscopy (SEM) produces microstructure images (enamel prism and bone lacuna-canalicular). Complementarily to structural analysis by µCT and SEM, microhardness is one of the informative parameters to evaluate how structural changes alter mechanical properties. Despite being a useful parameter, studies on microhardness of alveolar bone in oral diseases are limited. To date, divergent microhardness measurement methods have been reported. Since microhardness values vary depending on the sample preparation (polishing and flat surface) and indentation sites, diverse protocols can cause discrepancies among studies. Standardization of the microhardness protocol is essential for consistent and accurate evaluation in oral disease models. In the present study, we demonstrate a standardized protocol for microhardness analysis in tooth and alveolar bone. Specimens used are as follows: for the dental fluorosis model, incisors were collected from mice treated with/without fluoride-containing water for 6 weeks; for ligature-induced periodontal bone resorption (L-PBR) model, alveolar bones with periodontal bone resorption were collected from mice ligated on the maxillary 2nd molar. At 2 weeks after the ligation, the maxilla was collected. Vickers hardness was analyzed in these specimens according to the standardized protocol. The protocol provides detailed materials and methods for resin embedding, serial polishing, and indentation sites for incisors and alveolar. To the best of our knowledge, this is the first standardized microhardness protocol to evaluate the mechanical properties of tooth and alveolar bone in rodent oral disease models.


Assuntos
Processo Alveolar , Modelos Animais de Doenças , Microtomografia por Raio-X , Animais , Camundongos , Processo Alveolar/diagnóstico por imagem , Microtomografia por Raio-X/métodos , Fluorose Dentária/diagnóstico por imagem , Fluorose Dentária/patologia , Dureza , Incisivo/diagnóstico por imagem , Dente/diagnóstico por imagem
2.
BMC Ecol Evol ; 24(1): 59, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38730384

RESUMO

The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.


Assuntos
Fósseis , Dente , Animais , Dente/anatomia & histologia , Biodiversidade , Argentina , Filogenia
5.
PLoS One ; 19(5): e0300749, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38723036

RESUMO

This paper aims to re-examine the dietary practices of individuals buried at Sigatoka Sand Dunes site (Fiji) in Burial Ground 1 excavated by Simon Best in 1987 and 1988 using two approaches and a reassessment of their archaeological, bioarchaeological and chronological frame. First, stable carbon and nitrogen isotope analysis was applied to document dietary changes between childhood and adulthood using an intra-individual approach on paired bone-tooth. Second, the potential adaptation of the individuals to their environment was evaluated through regional and temporal comparisons using inter-individual bone analysis. Ten AMS radiocarbon dates were measured directly on human bone collagen samples, placing the series in a range of approximately 600 years covering the middle of the first millennium CE (1,888 to 1,272 cal BP). δ13C and δ15N ratios were measured on bone and tooth collagen samples from 38 adult individuals. The results show that δ15N values from tooth are higher than those s from bone while bone and tooth δ13C values are similar, except for females. Fifteen individuals were included in an intra-individual analysis based on paired bone and tooth samples, which revealed six dietary patterns distinguished by a differential dietary intake of marine resources and resources at different trophic levels. These highlight sex-specific differences not related to mortuary practices but to daily life activities, supporting the hypothesis of a sexual division of labour. Compared to other Southwest Pacific series, Sigatoka diets show a specific trend towards marine food consumption that supports the hypothesis of a relative food self-sufficiency requiring no interactions with other groups.


Assuntos
Osso e Ossos , Sepultamento , Isótopos de Carbono , Isótopos de Nitrogênio , Humanos , Isótopos de Carbono/análise , Feminino , Isótopos de Nitrogênio/análise , Masculino , Sepultamento/história , Osso e Ossos/química , Adulto , Fiji , Arqueologia , Dieta/história , Colágeno , História Antiga , Dente/química , Criança , Datação Radiométrica/métodos
6.
BMC Oral Health ; 24(1): 500, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38724912

RESUMO

BACKGROUND: Teeth identification has a pivotal role in the dental curriculum and provides one of the important foundations of clinical practice. Accurately identifying teeth is a vital aspect of dental education and clinical practice, but can be challenging due to the anatomical similarities between categories. In this study, we aim to explore the possibility of using a deep learning model to classify isolated tooth by a set of photographs. METHODS: A collection of 5,100 photographs from 850 isolated human tooth specimens were assembled to serve as the dataset for this study. Each tooth was carefully labeled during the data collection phase through direct observation. We developed a deep learning model that incorporates the state-of-the-art feature extractor and attention mechanism to classify each tooth based on a set of 6 photographs captured from multiple angles. To increase the validity of model evaluation, a voting-based strategy was applied to refine the test set to generate a more reliable label, and the model was evaluated under different types of classification granularities. RESULTS: This deep learning model achieved top-3 accuracies of over 90% in all classification types, with an average AUC of 0.95. The Cohen's Kappa demonstrated good agreement between model prediction and the test set. CONCLUSIONS: This deep learning model can achieve performance comparable to that of human experts and has the potential to become a valuable tool for dental education and various applications in accurately identifying isolated tooth.


Assuntos
Aprendizado Profundo , Dente , Humanos , Dente/anatomia & histologia , Dente/diagnóstico por imagem , Fotografia Dentária/métodos
7.
Science ; 384(6697): 798-802, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38753790

RESUMO

Although tool use may enhance resource utilization, its fitness benefits are difficult to measure. By examining longitudinal data from 196 radio-tagged southern sea otters (Enhydra lutris nereis), we found that tool-using individuals, particularly females, gained access to larger and/or harder-shelled prey. These mechanical advantages translated to reduced tooth damage during food processing. We also found that tool use diminishes trade-offs between access to different prey, tooth condition, and energy intake, all of which are dependent on the relative prey availability in the environment. Tool use allowed individuals to maintain energetic requirements through the processing of alternative prey that are typically inaccessible with biting alone, suggesting that this behavior is a necessity for the survival of some otters in environments where preferred prey are depleted.


Assuntos
Lontras , Comportamento Predatório , Dente , Lontras/fisiologia , Animais , Feminino , Masculino , Comportamento Alimentar , Ingestão de Energia
8.
Science ; 384(6697): 740-741, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38753804

RESUMO

Using tools increases foraging success in sea otters and protects their teeth from damage.


Assuntos
Saúde Bucal , Lontras , Animais , Comportamento de Utilização de Ferramentas , Dente
9.
Int J Oral Sci ; 16(1): 34, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38719817

RESUMO

Accurate segmentation of oral surgery-related tissues from cone beam computed tomography (CBCT) images can significantly accelerate treatment planning and improve surgical accuracy. In this paper, we propose a fully automated tissue segmentation system for dental implant surgery. Specifically, we propose an image preprocessing method based on data distribution histograms, which can adaptively process CBCT images with different parameters. Based on this, we use the bone segmentation network to obtain the segmentation results of alveolar bone, teeth, and maxillary sinus. We use the tooth and mandibular regions as the ROI regions of tooth segmentation and mandibular nerve tube segmentation to achieve the corresponding tasks. The tooth segmentation results can obtain the order information of the dentition. The corresponding experimental results show that our method can achieve higher segmentation accuracy and efficiency compared to existing methods. Its average Dice scores on the tooth, alveolar bone, maxillary sinus, and mandibular canal segmentation tasks were 96.5%, 95.4%, 93.6%, and 94.8%, respectively. These results demonstrate that it can accelerate the development of digital dentistry.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Tomografia Computadorizada de Feixe Cônico/métodos , Humanos , Processo Alveolar/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Inteligência Artificial , Seio Maxilar/diagnóstico por imagem , Seio Maxilar/cirurgia , Mandíbula/diagnóstico por imagem , Mandíbula/cirurgia , Dente/diagnóstico por imagem
10.
Cient. dent. (Ed. impr.) ; 21(1): 1-10, abr.-2024. ilus
Artigo em Espanhol | IBECS | ID: ibc-232708

RESUMO

Introducción: la pérdida ósea tras las extracciones puede requerir en el maxilar posterior la realización de una elevación de seno para la correcta colocación de implantes. El hueso autólogo se considera el gold estándar, pero tiene una alta tasa de reabsorción y morbilidad, haciendo que haya otras alternativas como el diente autólogo, con buenos resultados en procedimientos regenerativos. Este caso clínico evalúa a nivel clínico, radiográfico e histomorfométrico el empleo del diente autólogo en elevación de seno maxilar y el comportamiento de dos implantes colocados de manera diferida. Caso clínico: se presenta el caso de una mujer de 48 años, que acudió a consulta para reponer el sector posterior derecho. Se realizó la exodoncia del 4.8 como diente donante para utilizarlo como biomaterial en una elevación de seno de acceso lateral, colocando dos implantes seis meses tras la intervención, y evaluándolos seis meses tras su carga protésica. Discusión: el diente autólogo en el presente caso clínico presentó un 30,56% de hueso neoformado tras seis meses de espera, con mejores resultados que al emplear aloinjertos y xenoinjertos. Además, diferentes aspectos culturales y étnicos respaldan la aceptación del diente autólogo por parte de los pacientes, aunque se necesitan más estudios a largo plazo para evaluar la estabilidad de este tipo de injerto en elevación de seno maxilar. Conclusiones: el diente autólogo en la elevación de seno ofrece biocompatibilidad, baja incidencia de complicaciones y buena aceptación por parte del paciente, con un buen comportamiento clínico y radiográfico de los implantes, a pesar del poco tiempo transcurrido en este caso tras la carga. (AU)


Introduction: Bone loss after extractions may require a sinus elevation to be performed in the posterior maxilla for the correct placement of implants. Autologous bone is considered the gold standard, but has a high rate of resorption and morbidity, leading to other alternatives such as autologous tooth, with good results in regenerative procedures. This case report evaluates at the clinical, radiographic and histomorphometric level the use of the autologous tooth in maxillary sinus elevation and the behaviour of two implants placed in a delayed manner. Case report: The case is presented of a 48-year-old woman who came for consultation to replace the right posterior sector. The extraction of 4.8 as a donor tooth was performed to use it as a biomaterial in a lateral access sinus elevation, placing two implants six months after the intervention, and evaluating them six months after their prosthetic loading. Discussion: The autologous tooth in this case report showed 30.56% of newly formed bone following a six-month wait, with better results than when allografts and xenografts were used. In addition, different cultural and ethnic aspects support the acceptance of the autologous tooth by patients. However, more longterm studies are needed to evaluate the stability of this type of graft in maxillary sinus elevation. Conclusions: The autologous tooth in the sinus elevation offers biocompatibility, low incidence of complications and good patient acceptance, with good clinical and radiographic behaviour of the implants, despite the short time elapsed in this case after loading.(AU)


Assuntos
Humanos , Dente , Dentina , Seio Maxilar , Extração Dentária , Implantes Dentários
11.
Compend Contin Educ Dent ; 45(4): 214, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38622082

RESUMO

Hypoplastic maxilla is a common skeletal anomaly that compromises function and esthetics. Beyond just a narrow-appearing smile, this abnormality presents significant restorative challenges in adult patients as it is often associated with crowding, compromised axial inclination of the teeth, lack of alveolar bone support, root proximity, and occlusal trauma.1 Recent research also confirms association of maxillary deficiency with nasal stenosis and a predisposition to compromised nasal airflow and pharyngeal collapse during sleep.2,3 Maxillary transverse skeletal deficiency is often but not always associated with posterior dental cross-bite. In most cases, maxillary posterior teeth are flared buccally and mandibular posterior teeth are excessively lingually inclined masking the underlying skeletal problem.4 Advances in 3D imaging in dentistry, namely ultra-low radiation cone-beam imaging technology, have significantly enhanced clinicians' ability to diagnose and subsequently treat a maxillary transverse deficiency.5.


Assuntos
Má Oclusão , Aparelhos Ortodônticos Removíveis , Ortodontia , Dente , Adulto , Humanos , Estética Dentária , Má Oclusão/terapia , Maxila , Técnica de Expansão Palatina , Tomografia Computadorizada de Feixe Cônico/métodos
12.
Lasers Surg Med ; 56(4): 371-381, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38563442

RESUMO

OBJECTIVES: To develop and practically test high-precision femtosecond laser ablation models for dental hard tissue that are useful for detailed planning of automated laser dental restorative treatment. METHODS: Analytical models are proposed, derived, and demonstrated for practical calculation of ablation rates, ablation efficiency and ablated morphology of human dental enamel and dentin using femtosecond lasers. The models assume an effective optical attenuation coefficient for the irradiated material. To achieve ablation, it is necessary for the local energy density of the attenuated pulse in the hard tissue to surpass a predefined threshold that signifies the minimum energy density required for material ionization. A 1029 nm, 40 W carbide 275 fs laser was used to ablate sliced adult human teeth and generate the data necessary for testing the models. The volume of material removed, and the shape of the ablated channel were measured using optical profilometry. RESULTS: The models fit with the measured ablation efficiency curve against laser fluence for both enamel and dentin, correctly capturing the fluence for optimum ablation and the volume of ablated material per pulse. The detailed shapes of a 400-micrometer wide channel and a single-pulse width channel are accurately predicted using the superposition of the analytical result for a single pulse. CONCLUSIONS: The findings have value for planning automated dental restorative treatment using femtosecond lasers. The measurements and analysis give estimates of the optical properties of enamel and dentin irradiated with an infrared femtosecond laser at above-threshold fluence and the proposed models give insight into the physics of femtosecond laser processing of dental hard tissue.


Assuntos
Terapia a Laser , Dente , Humanos , Dentina/cirurgia , Lasers , Luz
13.
Bioinspir Biomim ; 19(3)2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38579734

RESUMO

Nature is filled with materials that are both strong and light, such as bones, teeth, bamboo, seashells, arthropod exoskeletons, and nut shells. The insights gained from analyzing the changing chemical compositions and structural characteristics, as well as the mechanical properties of these materials, have been applied in developing innovative, durable, and lightweight materials like those used for impact absorption. This research concentrates on the involucres of Job's tears (Coix lacryma-jobivar.lacryma-jobi), which are rich in silica, hard, and serve to encase the seeds. The chemical composition and structural characteristics of involucres were observed using scanning electron microscopy and energy-dispersive x-ray spectroscopy and optical microscopy with safranin staining. The hardness of the outer and inner surfaces of the involucre was measured using the micro-Vickers hardness test, and the Young's modulus of the involucre's cross-section was measured using nanoindentation. Additionally, the breaking behavior of involucres was measured through compression test and three-point bending tests. The results revealed a smooth transition in chemical composition, as well as in the orientation and dimensions of the tissues from the outer to the inner layers of involucres. Furthermore, it was estimated that the spatial gradient of the Young's modulus is due to the gradient of silica deposition. By distributing the hard, brittle silica in the outer layer and elastoplastic organic components in the middle and inner layers, the involucres effectively respond to compressive and tensile stresses that occur when loads are applied to the outside of the involucre. Furthermore, the involucres are reinforced in both meridional and equatorial directions by robust fibrovascular bundles, fibrous bundles, and the inner layer's sclerenchyma fibers. From these factors, it was found that involucres exhibit high toughness against loads from outside, making it less prone to cracking.


Assuntos
Artrópodes , Coix , Dente , Animais , Coix/química , Dióxido de Silício
14.
Dental Press J Orthod ; 29(1): e2423217, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38567923

RESUMO

OBJECTIVE: This study evaluated the accuracy and precision of digital models acquisition using a home-built, low-cost scanning system based on the structured light method. METHODS: a plaster model (PM) was scanned using the experimental device (SL) and a dental desktop scanner (DS). The teeth dimensions of PM and SL models were measured in triplicate, with a caliper and digitally, respectively. The agreement of the measurements of each model was evaluated using the intraclass correlation coefficient, and the validity between the different measurement techniques was assessed using the Bland-Altman analysis. The accuracy and precision of the models were qualitatively investigated using the mesh superposition of the SL and DS models. RESULTS: A high intraclass correlation coefficient was observed in all models (PM=0.964; SL1=0.998; SL2=0.995; SL3=0.998), and there was no statistical difference between the measurements of the SL models (p>0.05). PM and SL model measurements were found to be in good agreement, with only 3.57% of the observed differences between the same measurement being located outside 95% limits of agreement according to Bland and Altman (0.43 and -0.40 mm). In the superimpositions of SL-SL and SL-DS models, areas of discrepancy greater than 0.5 mm were observed mainly in interproximal, occlusal, and cervical sites. CONCLUSION: These results indicate that the home-built SL scanning system did not possess sufficient accuracy and precision for many clinical applications. However, the consistency in preserving the dental proportions suggests that the equipment can be used for planning, storage, and simple clinical purposes.


Assuntos
Imageamento Tridimensional , Dente , Imageamento Tridimensional/métodos , Modelos Dentários , Reprodutibilidade dos Testes
15.
Prog Orthod ; 25(1): 13, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38584176

RESUMO

OBJECTIVES: To evaluate the accuracy of a semi-automatic 3D digital setup process in predicting the orthodontic treatment outcome achieved by labial fixed appliances. SUBJECTS AND METHODS: Twenty-five adult patients (18 to 24 years old) with class I malocclusion and moderate crowding were prospectively enrolled and received treatment on both jaws through the straight-wire technique. Prior to treatment commencement, a semi-automatic digital setup simulating the predicted treatment outcome was performed for each patient through Orthoanalyzer software (3Shape®, Copenhagen, Denmark) to obtain the prediction model. This was compared to the final outcome model through 3D superimposition methods. Metric variables and inspection of color-coded distance maps were used to detect how accurately the digital setup predicts the actual treatment outcome. RESULTS: The mean absolute distances (MAD) between the superimposed dental arches of the predicted and the final models were: 0.77 ± 0.13 mm following superimposition on the palate, 0.52 ± 0.06 mm following superimposition on the maxillary dental arch, and 0.55 ± 0.15 mm following superimposition on the mandibular dental arch. The MAD at the palatal reference area was 0.09 ± 0.04 mm. Visualization of color-coded distance maps indicated that the digital setup accurately predicted the final teeth position in a few cases. Almost half of the cases had posteriorly wider upper and lower dental arches and palatally/lingually positioned or inclined anterior teeth, whereas the rest still showed errors within 2-3 mm, distributed over the entire dental arches with no distinct pattern. CONCLUSIONS: The accuracy of semi-automatic prediction of the labial fixed appliance treatment outcome in Class I cases with moderate crowding is not yet sufficient. While average measures showed deviations less than 1 mm, examination of individual color-coded distance maps revealed significant disparities between the simulated and the actual results.


Assuntos
Má Oclusão Classe I de Angle , Má Oclusão , Dente , Adulto , Humanos , Adolescente , Adulto Jovem , Estudos Prospectivos , Má Oclusão/terapia , Má Oclusão Classe I de Angle/terapia , Aparelhos Ortodônticos Fixos , Aparelhos Ortodônticos
16.
PeerJ ; 12: e17153, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38560470

RESUMO

Teleosauroid thalattosuchians were a clade of semi-aquatic crocodylomorphs that achieved a broad geographic distribution during the Mesozoic. While their fossils are well documented in Western European strata, our understanding of teleosauroids (and thalattosuchians in general) is notably poorer in Central-Eastern Europe, and from Poland in particular. Herein, we redescribe a teleosauroid rostrum (MZ VIII Vr-72) from middle Oxfordian strata of Zalecze Wielkie, in south-central Poland. Until now, the specimen has been largely encased in a block of limestone. After preparation, its rostral and dental morphology could be evaluated, showing the specimen to be a non-machimosaurin machimosaurid, similar in morphology to taxa Neosteneosaurus edwardsi and Proexochokefalos heberti. The well-preserved teeth enable us to study the specimen feeding ecology through the means of comparing its teeth to other teleosauroids through PCoA analysis. Comparisons with inferred closely related taxa suggest that the referred specimen was a macrophagous generalist. Notably, MZ VIII Vr-72 displays a prominent pathological distortion of the anterior rostrum, in the form of lateral bending. The pathology affects the nasal passage and tooth size and position, and is fully healed, indicating that, despite its macrophagous diet, it did not prevent the individual from food acquisition.


Assuntos
Evolução Biológica , Dente , Filogenia , Polônia , Dente/anatomia & histologia , Fósseis
17.
Proc Biol Sci ; 291(2020): 20232830, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38593847

RESUMO

The bone-eating worm Osedax is a speciose and globally distributed clade, primarily found on whale carcasses in marine environments. The earliest fossil evidence for Osedax borings was previously described in plesiosaur and sea turtle bones from the mid-Cretaceous of the United Kingdom, representing the only unequivocal pre-Oligocene occurrences. Confirming through CT scanning, we present new evidence of Osedax borings in three plesiosaur specimens and, for the first time, identify borings in two mosasaur specimens. All specimens are from the Late Cretaceous: one from the Cenomanian of the United Kingdom, two from the Campanian of the southeastern United States, and two from the Maastrichtian of Belgium. This extends the geographic range of Osedax in the Cretaceous to both sides of the northern Atlantic Ocean. The bones contain five borehole morphotypes, potentially created by different species of Osedax, with the Cenomanian specimen containing three morphotypes within a single tooth. This combined evidence of heightened species diversity by the Cenomanian and broad geographic range by the Campanian potentially indicates an earlier origin and diversification for this clade than previously hypothesized. Preservational biases indicate that Osedax was probably even more widely distributed and speciose in the Cretaceous than apparent in the fossil record.


Assuntos
Poliquetos , Dente , Animais , Osso e Ossos , Répteis , Tomografia Computadorizada por Raios X , Cetáceos , Fósseis
18.
Nature ; 628(8008): 569-575, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38570681

RESUMO

Shuotheriids are Jurassic mammaliaforms that possess pseudotribosphenic teeth in which a pseudotalonid is anterior to the trigonid in the lower molar, contrasting with the tribosphenic pattern of therian mammals (placentals, marsupials and kin) in which the talonid is posterior to the trigonid1-4. The origin of the pseudotribosphenic teeth remains unclear, obscuring our perception of shuotheriid affinities and the early evolution of mammaliaforms1,5-9. Here we report a new Jurassic shuotheriid represented by two skeletal specimens. Their complete pseudotribosphenic dentitions allow reidentification of dental structures using serial homology and the tooth occlusal relationship. Contrary to the conventional view1,2,6,10,11, our findings show that dental structures of shuotheriids can be homologized to those of docodontans and partly support homologous statements for some dental structures between docodontans and other mammaliaforms6,12. The phylogenetic analysis based on new evidence removes shuotheriids from the tribosphenic ausktribosphenids (including monotremes) and clusters them with docodontans to form a new clade, Docodontiformes, that is characterized by pseudotribosphenic features. In the phylogeny, docodontiforms and 'holotherians' (Kuehneotherium, monotremes and therians)13 evolve independently from a Morganucodon-like ancestor with triconodont molars by labio-lingual widening their posterior teeth for more efficient food processing. The pseudotribosphenic pattern passed a cusp semitriangulation stage9, whereas the tribosphenic pattern and its precursor went through a stage of cusp triangulation. The two different processes resulted in complex tooth structures and occlusal patterns that elucidate the earliest diversification of mammaliaforms.


Assuntos
Evolução Biológica , Fósseis , Mamíferos , Dente , Animais , Eutérios/anatomia & histologia , Mamíferos/anatomia & histologia , Mamíferos/classificação , Mamíferos/fisiologia , Marsupiais/anatomia & histologia , Dente Molar/anatomia & histologia , Dente Molar/fisiologia , Filogenia , Dente/anatomia & histologia , Dente/fisiologia , Mastigação
19.
BMC Ecol Evol ; 24(1): 46, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38627692

RESUMO

BACKGROUND: Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution of the highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, are poorly known. The early-diverging neornithischian Jeholosaurus, a small, bipedal herbivorous dinosaur from the Early Cretaceous Jehol Biota, is an important taxon for understanding ornithischian dental evolution, but its dental morphology was only briefly described previously and its tooth replacement is poorly known. RESULTS: CT scanning of six specimens representing different ontogenetic stages of Jeholosaurus reveals significant new information regarding the dental system of Jeholosaurus, including one or two replacement teeth in nearly all alveoli, relatively complete tooth resorption, and an increase in the numbers of alveoli and replacement teeth during ontogeny. Reconstructions of Zahnreihen indicate that the replacement pattern of the maxillary dentition is similar to that of the dentary dentition but with a cyclical difference. The maxillary tooth replacement rate in Jeholosaurus is probably 46 days, which is faster than that of most other early-diverging ornithischians. During the ontogeny of Jeholosaurus, the premaxillary tooth replacement rate slows from 25 days to 33 days with similar daily dentine formation. CONCLUSIONS: The tooth replacement rate exhibits a decreasing trend with ontogeny, as in Alligator. In a phylogenetic context, fast tooth replacement and multi-generation replacement teeth have evolved at least twice independently in Ornithopoda, and our analyses suggest that the early-diverging members of the major ornithischian clades exhibit different tooth replacement patterns as an adaption to herbivory.


Assuntos
Dinossauros , Dente , Animais , Filogenia , Dinossauros/anatomia & histologia , Herbivoria , Fósseis , Dente/diagnóstico por imagem , Dente/cirurgia , Dente/anatomia & histologia
20.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 55(2): 469-474, 2024 Mar 20.
Artigo em Chinês | MEDLINE | ID: mdl-38645865

RESUMO

Craniomaxillofacial development involves a series of highly ordered temporal-spatial cellular differentiation processes in which a variety of cell signaling factors, such as fibroblast growth factors, play important regulatory roles. As a classic fibroblast growth factor, fibroblast growth factor 7 (FGF7) serves a wide range of regulatory functions. Previous studies have demonstrated that FGF7 regulates the proliferation and migration of epithelial cells, protects them, and promotes their repair. Furthermore, recent findings indicate that epithelial cells are not the only ones subjected to the broad and powerful regulatory capacity of FGF7. It has potential effects on skeletal system development as well. In addition, FGF7 plays an important role in the development of craniomaxillofacial organs, such as the palate, the eyes, and the teeth. Nonetheless, the role of FGF7 in oral craniomaxillofacial development needs to be further elucidated. In this paper, we summarized the published research on the role of FGF7 in oral craniomaxillofacial development to demonstrate the overall understanding of FGF7 and its potential functions in oral craniomaxillofacial development.


Assuntos
Fator 7 de Crescimento de Fibroblastos , Humanos , Fator 7 de Crescimento de Fibroblastos/metabolismo , Fator 7 de Crescimento de Fibroblastos/genética , Animais , Crânio/crescimento & desenvolvimento , Crânio/metabolismo , Desenvolvimento Maxilofacial/fisiologia , Dente/metabolismo , Dente/crescimento & desenvolvimento
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