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1.
Biomed Res Int ; 2019: 4934128, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31317031

RESUMO

Introduction: With an increasing demand for orthodontic treatment for adult patients, orthodontic professionals are constantly seeking novel strategies and technologies that can accelerate tooth movement in order to shorten the treatment period. For instance, in recent years, the influences of different surgical techniques on orthodontic tooth movement in the ipsilateral side of surgery were intensively investigated. Here, we attempt to examine if corticotomy could also affect the rate of tooth movement in the contralateral side of the surgery by using a rodent model. Materials and Methods: 72 eight-week-old Sprague-Dawley rats were randomly divided into three groups as follows: the Control group (orthodontic treatment devices delivered only, no tooth movement), the orthodontic tooth movement (OTM) group (orthodontic treatment devices delivered and orthodontic treatment performed), and the Corticotomy + OTM group (remote corticotomy performed, orthodontic treatment devices delivered, followed by orthodontic treatment). The surgical procedure was conducted on the right side of the maxilla at the time of appliance placement and a force of 60 g was applied between the maxillary left first molar and maxillary incisors using nickel-titanium springs to stimulate OTM. The OTM distance and speed were tracked at 3, 7, 14, and 28 days post-surgery, followed by histological and immunohistochemical assessments. Results: In comparison with orthodontic treatment only, the contralateral corticotomy significantly accelerated OTM. Furthermore, animals undergoing corticotomy + OTM presented with a greater number of osteoclasts on the compression side, stronger staining of the osteogenic marker on the tension side, and higher expression of an inflammatory marker than the OTM group animals. Conclusion: Our current study demonstrates that remote corticotomy effectively accelerates alveolar bone remodeling and OTM. The study enriches our understanding of the regional acceleratory phenomenon (RAP) and offers an alternative strategy for accelerating OTM to shorten the orthodontic treatment period.


Assuntos
Remodelação Óssea/efeitos dos fármacos , Reabsorção Óssea/cirurgia , Incisivo/cirurgia , Osteogênese/efeitos dos fármacos , Animais , Modelos Animais de Doenças , Humanos , Incisivo/crescimento & desenvolvimento , Incisivo/patologia , Maxila/crescimento & desenvolvimento , Maxila/patologia , Maxila/cirurgia , Dente Molar/crescimento & desenvolvimento , Dente Molar/patologia , Dente Molar/cirurgia , Níquel/uso terapêutico , Fios Ortodônticos , Osteoclastos/metabolismo , Osteoclastos/patologia , Ratos , Titânio/uso terapêutico , Técnicas de Movimentação Dentária
2.
Georgian Med News ; (287): 111-114, 2019 Feb.
Artigo em Russo | MEDLINE | ID: mdl-30958300

RESUMO

Nowadays new efficient methods of dental correction and modern methods of abnormal bite correction are suggested. In this regard, seems to be important to study the existence of individual anatomical variability range of the maxilla and its structures. The research has been conducted on 100 bone samples of integral and fragmented skulls from the collections of anatomy department of Kharkiv National Medical University. In the conditions of research, detailed osteometry of the maxilla has been took place. Therefore, measurements have been included: length (from the posterior margin of the front incisive alveoli to the posterior margin of the hard palate); width (between the inner margins of the second molars alveoli); length (perimeter) of the dental arch. The length of the maxillary alveolar arch gradually increases from brachycephalic to mesocephalic and dolichocephalic of both genders. The width of the upper alveolar arch reaches the maximum values in brachycephalic type, an intermediate place is occupied by mesocephalic, dolichocephalic type of the skull corresponds to the minimal range. In adulthood have been found the prevalence of right-sided asymmetry of the external margin of the upper alveolar arch and hence the similar localization of the maxilla teeth row, due to the right-sided mastication type or its predominance throughout the life. According to received data, there are three main forms of upper alveolar arch in adulthood: expanded-arch, which differs by deployed curvature around the perimeter and typical for brachycephalic; medium-arch with the presence of different length along the perimeter in mesocephalic; narrow-arch with the predominance of longitudinal perimeters in dolichocephalic type. Maxillary dental arch lies along the lower edge of the teeth, starting from the frontal incisors. Alveolar arch passes through the alveolar crest (lower edge of the gums). Basal arch is going on the tops of the teeth roots, otherwise known as apical arch. Given that, the crowns of the upper jaw teeth are always inclined vestibulary and roots of teeth - orally. Their ratio to the maxilla expressed that the widest perimeter has dental arch, middle position - alveolar arch and the smallest one is apical. The last one withstands the maximal masticatory pressure and hence beginning of the maxillary buttresses at this level.


Assuntos
Arco Dental/anatomia & histologia , Maxila/anatomia & histologia , Dente Molar/crescimento & desenvolvimento , Oclusão Dentária , Feminino , Humanos , Masculino , Desenvolvimento Maxilofacial , Raiz Dentária
3.
Curr Med Sci ; 39(2): 317-324, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31016528

RESUMO

This longitudinal study aims to analyze the different modes of the maxillary and mandibular tooth displacement in subjects, who were aged 12.5-17.5 years (150-210 months), with untreated normal (Class I) occlusion. Longitudinal lateral cephalograms for a set of 10 subjects (7 females and 3 males) at consecutive annual time points were selected and monitored. Data were analyzed on the basis of the superimpositions of serial tracings of lateral cephalograms on stable anterior cranial base, the anatomies of the maxillary and mandibular structures. The horizontal and vertical displacements of the first molar and incisor were assessed by t-test. The local and the secondary tooth displacements with growth contributed to the total horizontal and vertical displacements of the molars and incisors of the subjects. In the total tooth displacement, the horizontal growth of maxilla and mandible had the same contribution as the local tooth displacements. The vertical maxillary growth played a smaller role than the local drift, and mandibular remodeling went in a reverse direction with the local tooth drift. The first molars moved more forward than the incisors in the upper and lower arches. Both the upper and lower first molars showed forward tipping. The analysis of tooth displacement may be utilized in making orthodontic treatment plan, including anchorage or torque control.


Assuntos
Mandíbula/crescimento & desenvolvimento , Maxila/crescimento & desenvolvimento , Adolescente , Grupo com Ancestrais do Continente Asiático , Criança , Feminino , Humanos , Incisivo/crescimento & desenvolvimento , Estudos Longitudinais , Masculino , Dente Molar/crescimento & desenvolvimento
4.
Orthod Fr ; 90(1): 55-63, 2019 Mar.
Artigo em Francês | MEDLINE | ID: mdl-30994449

RESUMO

INTRODUCTION: Recent observations performed in the orthodontic department of La Pitié-Salpêtrière hospital in Paris reported an increase of non-familial eruption defects of permanent molars. Our recent data have evidenced the involvement of osteoclasts (OC) in both the eruption and the dental retention processes through the RANKL/RANK/OPG signaling pathway. These facts are at the origin of the hypothesis of the existence of an environmental etiology for those eruption defects that would correspond to the perturbation of cellular autocrine/paracrine signaling pathways as the RANKL/ RANK/OPG. MATERIALS AND METHODS: C57BL/6 mice were submitted to repeated injections with anti-RANKL neutralizing antibody during the nine days following birth. A phenotypic comparison with transgenic mice overexpressing RANK was performed for the functional characterization of the RANKL/RANK/OPG pathway. The dento-alveolar complex was analyzed using micro-CT for bone density and Masson's trichrome staining for histological examination. RESULTS: The RANKL transient invalidation of RANKL stopped the molar root development and tooth eruption contrary to transgenic mice overexpressing RANK. The recruitment and the OC activity were strongly impacted. DISCUSSION: This research is of direct clinical interest in understanding the pathology of eruption as indirect in establishing orthodontic treatment protocols for particular cases.


Assuntos
Anticorpos Monoclonais/farmacologia , Dente Molar/efeitos dos fármacos , Ligante RANK/imunologia , Erupção Dentária/efeitos dos fármacos , Raiz Dentária/efeitos dos fármacos , Animais , Anticorpos Monoclonais/administração & dosagem , Injeções Subcutâneas , Camundongos , Camundongos Endogâmicos C57BL , Dente Molar/diagnóstico por imagem , Dente Molar/crescimento & desenvolvimento , Ligante RANK/antagonistas & inibidores , Raiz Dentária/diagnóstico por imagem , Raiz Dentária/crescimento & desenvolvimento , Microtomografia por Raio-X
5.
J Mol Histol ; 50(3): 179-188, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30863901

RESUMO

Interactions between the ectodermal and mesenchymal tissues are the basis of the central mechanism regulating tooth development. Based on this epithelial-mesenchymal interaction (EMI), we demonstrated that copine-7 (CPNE7) is secreted by preameloblasts and regulates the differentiation of mesenchymal cells of dental or non-dental origin into odontoblasts. However, the precise expression patterns of CPNE7 in the stages of tooth development have not yet been elucidated. The aim of the present study was to establish the spatiotemporal expression pattern of CPNE7 during mouse tooth development. To examine the spatiotemporal expression patterns of CPNE7 during mouse tooth development, we investigate the distribution of CPNE7 in the embryonic and postnatal developing mouse tooth. Immunohistochemistry, in situ hybridization, real-time PCR, and western blot analysis are performed to investigate the CPNE7 expression pattern during tooth development of the mandibular mouse first molar. During the initiation stage (bud stage), CPNE7 protein expression is observed in the dental epithelium but not yet in the dental mesenchyme. At E18 (bell stage), expression of CPNE7 protein and mRNA is primarily observed in ectomesenchymal cells of dental papilla. At P7 (crown formation stage), CPNE7 is localized in differentiating odontoblasts but weak expression is detected in mature ameloblasts. These findings suggest that CPNE7 secreted by dental epithelium induces the differentiation of ectomesenchymal cells into preodontoblast in concert with EMI. CPNE7 is clearly expressed in differentiating odontoblasts and the odontoblast process during dentinogenesis, but is no longer expressed in fully differentiated odontoblasts. Furthermore, CPNE7 is expressed in the Hertwig's epithelial root sheath (HERS) and in the facing preodontoblasts during root dentin formation. Taken together, these results illustrate the dynamic expression of CPNE7 during tooth development and suggest its important function in entire stages of tooth development.


Assuntos
Diferenciação Celular/genética , Dentinogênese/genética , Proteínas de Membrana/metabolismo , Dente Molar/crescimento & desenvolvimento , Dente/crescimento & desenvolvimento , Ameloblastos/citologia , Ameloblastos/metabolismo , Animais , Papila Dentária/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Membrana/genética , Camundongos , Dente Molar/metabolismo , Odontoblastos/citologia , Odontoblastos/metabolismo , Dente/metabolismo
6.
Arch Oral Biol ; 101: 64-76, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30903951

RESUMO

OBJECTIVES: We aimed to investigate the effects of mechanical force application on the developing root apex in vivo. DESIGN: Mechanical force was applied on the maxillary first molars of Sprague-Dawley rats at postnatal day 21 for 1, 3, 5, and 7 days to induce tooth movement. We observed the developing root apex of the mesial root of first molar by using micro-focus X-ray computed tomography, histological staining, immunohistochemistry and in situ hybridization to analyze apical cell proliferation and gene expression. Moreover, the force was released after 3 and 7 days of tooth movement, and root apical morphology at postnatal day 35 was subsequently observed. RESULTS: After 1 and 3 days of tooth movement, root apical morphology was altered by increasing immune-reactivity of laminin in the forming periodontal ligament. After 7 days of tooth movement, the root length decreased significantly with bending root apex, decreased cell proliferation and altered gene expression in developing root apex. At postnatal day 35, apical morphology showed no obvious abnormality when the force was released after 3 days of tooth movement, whereas root apical bending was not rescued when the force was released after 7 days. CONCLUSIONS: Relatively short-term force application had no obvious adverse effects on the developing root apex. However, relatively long-term force application altered root apex by affecting Hertwig's epithelial root sheath morphology and apical cellular behavior.


Assuntos
Dente Molar/crescimento & desenvolvimento , Estresse Mecânico , Ápice Dentário/crescimento & desenvolvimento , Animais , Ligamento Periodontal , Ratos , Ratos Sprague-Dawley , Técnicas de Movimentação Dentária
7.
Forensic Sci Int ; 297: 243-248, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30844636

RESUMO

The aims of the present study were to validate the discriminatory potential of Cameriere's third molar maturity index (I3M) cut-off value of I3M < 1.1 and whether closed apices of permanent second mandibular molar (I2M = 0.0) and I3M < 1.1 indicate the legal age of 14 years and older. A digital orthopantomograms of 804 healthy South Indian children, aged between 10 and 18 years, were collected retrospectively, and mineralization of the third and second left mandibular molars was analyzed by Cameriere's method. The proportion of accurately classified (Ac) individuals using the cut-off value of I3M < 1.1 was 79.4% for males, with Bayes post-test probability (Bayes PTP) of 68.8%. For females, Ac was 79.9% and Bayes PTP was 70.9%. The sensitivity was 94.8% and 98.2% for males and females, and the specificity was 58.7% and 62.8%, respectively. The combination of both variables, I3M < 1.1 and I2M = 0.0, increased the Ac to 87.2% and 94.4% in males and females, the specificity to 98.6% and 99.2%, and Bayes PTP to 98.2% and 94.4%, respectively. In conclusion, the suggested cut-off value of I3M < 1.1 is of moderate accuracy in discriminating individuals between 14 years or older from those under 14 years in the studied population. A combination of both variables, I2M = 0.0 and I3M < 1.1, the discriminating test achieves an excellent specificity and Bayes PTP, which is mandatory for the forensic and medicolegal purposes.


Assuntos
Determinação da Idade pelos Dentes/métodos , Dente Molar/diagnóstico por imagem , Dente Molar/crescimento & desenvolvimento , Ápice Dentário/diagnóstico por imagem , Ápice Dentário/crescimento & desenvolvimento , Adolescente , Criança , Estudos Transversais , Dentição Permanente , Feminino , Humanos , Índia , Funções Verossimilhança , Masculino , Mandíbula , Radiografia Panorâmica , Estudos Retrospectivos , Sensibilidade e Especificidade
8.
J Indian Soc Pedod Prev Dent ; 37(1): 107-109, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30804316

RESUMO

Teeth which erupt in the 1st month of postnatal life are known as "neonatal tooth." The incidence of these teeth ranges from 1:2000 to 1:3500 live births. Natal teeth are more common in mandibular central incisor region, followed by maxillary incisor region and mandibular canine region. The neonatal or natal teeth in the maxillary molar region are a rare occurrence. This article represents a rare case of the neonatal tooth with Langerhans cell histiocytosis.


Assuntos
Histiocitose de Células de Langerhans/patologia , Dente Molar/anormalidades , Erupção Dentária , Humanos , Lactente , Masculino , Maxila/anormalidades , Dente Molar/crescimento & desenvolvimento , Dente Molar/patologia
9.
Biomed Res Int ; 2019: 6159490, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30809544

RESUMO

Miniature pigs, a valuable alternative model for understanding human tooth development, have deciduous teeth from all four tooth families that are replaced once by permanent molars. The extracellular matrix (ECM) supports cells and maintains the integrity of tooth germs during tooth development. However, details on the role of the ECM in tooth development are poorly understood. Here, we performed long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in the ECM components of deciduous tooth germs by RNA sequencing in miniature pigs. From the early cap to the late bell stages, we identified 4,562 and 3,238 differentially expressed genes (DEGs) from E40 to E50 and E50 to E60, respectively. In addition, a total of 1,464 differentially expressed lncRNAs from E40 to E50 and 969 differentially expressed lncRNAs from E50 to E60 were obtained. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that DEGs were enriched significantly for multiple signaling pathways, especially for the ECM pathway. We then outlined the detailed dynamic gene expression profiling of ECM components during deciduous molar development. Comparison of the cap and bell stages revealed that the structure and functions of the ECM dynamically changed. The ECM-related genes, including THBS1, COL4A5, COL4A6, COL1A1, CHAD, TNR, GP1BA, and ITGA3, were significantly changed, and some were shown to enrich during the bell stage development. Finally, we outlined the coexpression of lncRNAs and ECM properties during tooth development. We showed that the interplay of key lncRNAs could change ECM processes and influence the ECM establishment of tooth patterns to accomplish full tooth formation. These results might provide information to elucidate the regulation network of the lncRNA and ECM in tooth development.


Assuntos
Matriz Extracelular/genética , RNA Longo não Codificante/genética , RNA Mensageiro/genética , Dente Decíduo/crescimento & desenvolvimento , Animais , Regulação da Expressão Gênica no Desenvolvimento/genética , Redes Reguladoras de Genes/genética , Humanos , Dente Molar/crescimento & desenvolvimento , Suínos , Porco Miniatura , Germe de Dente/crescimento & desenvolvimento , Dente Decíduo/metabolismo
10.
Ann Anat ; 222: 146-152, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30599239

RESUMO

The formation of the alveolar bone, which houses the dental primordia, and later the roots of tooth, may serve as a model to approach general questions of alveolar bone formation. In this respect, this study aimed to investigate the potential interactions between the alveolar bone formation and tooth eruption by using finite element (FE) methods, and to figure out whether the expanding tooth systems induce shear stresses that lead to alveolar bone formation. 3D geometric surface models were generated from the 3D histological data of the heads of mice (C57 Bl/6J) ranging from stages embryonic (E) to postnatal (P) stages E15 to P20 using the reconstruction software 3-Matic. Bone, dentin, enamel and dental follicle around the primordia were generated and converted into 3D FE models. Models were imported into the FE software package MSC.Marc/Mentat. As material parameters of embryonic dentine, pulp, enamel, dental follicle, and bony structures basically are unknown, these were varied from 1% to 100% of the corresponding known material parameters for humans and a sensitivity analysis was performed. Surface loads were applied to the outside surface of dental follicle ranging from 0.1 to 5.0N/mm2. The validity of the model was analysed by comparing the activity pattern of the alveolar bone as determined in the histological study with the loading pattern from the numerical analysis. The results show that when varying the surface loads, the distribution of shear stresses remained same, and while varying the material properties of the hard tissues, the location of highest shear stresses remained stable. Comparison of the histologically determined growth regions with the distribution of shear stresses computed in the numerical model showed a very close agreement. The results provide a strong proof to support Blechschmidt's hypothesis that the bone in general is created under the influence of shear forces.


Assuntos
Desenvolvimento Ósseo/fisiologia , Mandíbula/crescimento & desenvolvimento , Dente Molar/crescimento & desenvolvimento , Adulto , Processo Alveolar/crescimento & desenvolvimento , Animais , Animais Recém-Nascidos , Esmalte Dentário/crescimento & desenvolvimento , Polpa Dentária/crescimento & desenvolvimento , Saco Dentário/crescimento & desenvolvimento , Dentina/crescimento & desenvolvimento , Feminino , Análise de Elementos Finitos , Humanos , Imagem Tridimensional , Mandíbula/embriologia , Camundongos , Camundongos Endogâmicos C57BL , Dente Molar/embriologia , Gravidez , Erupção Dentária
11.
Biochem Biophys Res Commun ; 509(4): 1008-1014, 2019 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-30654938

RESUMO

Tooth formation is accomplished under strict genetic programs. Although patients with chromosome 12q14 aberration shows tooth phenotype including the size and eruption timing with bone growth anomaly, its etiology is uncertain. Here, we examined expression of Hmga2, which is encoded at chromosome 12q14, in mouse tooth germs and analyzed the involvement in lower first molar (M1) and mandibular bone development. Hmga2 expression was immunohistochemically detected at enamel organ and the surrounding mesenchyme of the M1 germs. The expression was dynamically changed with gestation and rapidly decreased in postnatal mice. In Hmga2-/- mice, the M1 germs and crowns were diminished in size, and formation and eruption of molars were delayed with mandibular bone growth retardation. Hmga2 cDNA or siRNA transfection showed that Hmga2 transcriptionally up-regulates expression of stem cell factors, Sox2 and Nanog. They were co-localized with Hmga2 in the germs, but differentially distributed at enamel organ and mesenchyme in Hmga2-/- mice. These results demonstrate that Hmga2 expressed in tooth germs regulates the growth, sizing and eruption and stem cell factor expression in different compartment of the germ and associates with mandibular bone growth. Although future studies are needed, the present study demonstrates HMGA2 regulation of tooth genesis with skeletal development.


Assuntos
Proteína HMGA2/fisiologia , Proteína Homeobox Nanog/metabolismo , Fatores de Transcrição SOXB1/metabolismo , Animais , Regulação da Expressão Gênica no Desenvolvimento , Proteína HMGA2/análise , Proteína HMGA2/metabolismo , Imuno-Histoquímica , Mandíbula/crescimento & desenvolvimento , Camundongos , Dente Molar/crescimento & desenvolvimento , Odontogênese/efeitos dos fármacos
12.
J Mol Neurosci ; 68(3): 377-388, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30094580

RESUMO

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with neuroprotective and neurotrophic effects. This suggests its influence on the development of teeth, which are, similarly to the nervous system, ectoderm and neural crest derivatives. Our earlier studies have shown morphological differences between wild-type (WT) and PACAP-deficient mice, with upregulated sonic hedgehog (SHH) signaling in the lack of PACAP. Notch signaling is a key element of proper tooth development by regulating apoptosis and cell proliferation. In this study, our main goal was to evaluate the possible effects of PACAP on Notch signaling pathway. Immunohistochemical staining was performed of Notch receptors (Notch1, 2, 3, 4), their ligands [delta-like protein (DLL)1, 3, 4, Jagged1, 2], and intracellular target molecules [CSL (CBF1 humans/Su (H) Drosophila/LAG1 Caenorhabditis elegans transcription factor); TACE (TNF-α converting enzyme), NUMB] in molar teeth of 5-day-old WT, and homozygous and heterozygous PACAP-deficient mice. We measured immunopositivity in the enamel-producing ameloblasts and dentin-producing odontoblasts. Notch2 receptor and DLL1 expression were elevated in ameloblasts of PACAP-deficient mice compared to those in WT ones. The expression of CSL showed similar results both in the ameloblasts and odontoblasts. Jagged1 ligand expression was elevated in the odontoblasts of homozygous PACAP-deficient mice compared to WT mice. Other Notch pathway elements did not show significant differences between the genotype groups. The lack of PACAP leads to upregulation of Notch pathway elements in the odontoblast and ameloblast cells. The underlying molecular mechanisms are yet to be elucidated; however, we propose SHH-dependent and independent processes. We hypothesize that this compensatory upregulation of Notch signaling by the lack of PACAP could represent a salvage pathway in PACAP-deficient animals.


Assuntos
Dente Molar/metabolismo , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/genética , Receptor Notch1/metabolismo , Transdução de Sinais , Ameloblastos/metabolismo , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Jagged-1/genética , Proteína Jagged-1/metabolismo , Camundongos , Dente Molar/citologia , Dente Molar/crescimento & desenvolvimento , Odontoblastos/metabolismo , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/deficiência , Receptor Notch1/genética , Regulação para Cima
13.
J Exp Zool A Ecol Integr Physiol ; 331(2): 139-148, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30511369

RESUMO

One reason for the mammalian clade's success is the evolutionary diversity of their teeth. In herbivores, this is represented by high-crowned teeth evolved to compensate for wear caused by dietary abrasives like phytoliths and grit. Exactly how dietary abrasives wear teeth is still not understood completely. We fed four different pelleted diets of increasing abrasiveness (L: Lucerne; G: grass; GR: grass and rice husks; GRS: grass, rice husks, and sand) to four groups of a total of 28 adult goats, all with completely erupted third molars, over a six-month period. Tooth morphology was captured by medical computed tomography scans at the beginning and end of the controlled feeding experiment, and separation lines between the crown and root segments were defined in the upper right second molar (M2), to gauge absolute wear. Using bootstrapping, significant differences in volume loss between diets L/G and GR/GRS were detected. A small but nevertheless consistent volume gain was noted in the roots, and there was a significant, positive correlation between crown volume loss and root volume gain. This growth could possibly be attributed to the well-known process of cementum deposition and its relation with a putative feedback mechanism, in place to attenuate wear caused by abrasive diets.


Assuntos
Cabras/fisiologia , Dente Molar/crescimento & desenvolvimento , Desgaste dos Dentes/veterinária , Ração Animal , Animais
14.
BMC Evol Biol ; 18(1): 207, 2018 12 29.
Artigo em Inglês | MEDLINE | ID: mdl-30594146

RESUMO

BACKGROUND: Several lineages of herbivorous mammals have evolved hypsodont cheek teeth to increase the functional lifespan of their dentition. While the selective drivers of this trend and the developmental processes involved have been studied in greater detail, thus far no quantitative information is available on the relationship between additional investment into tooth growth and the resulting extension of the functional period of these teeth. To achieve this, we performed a detailed analysis of molar crown growth in known-age Soay sheep repeatedly injected with different fluorochromes. RESULTS: Our study revealed that in sheep molars especially the formation of the crown base portion is prolonged in comparison with other herbivorous artiodactyl species. Our results demonstrate that growth of the crown base accounted for more than half of the total crown formation time (CFT) of the anterior lobes of the first (approx. 220 days of total CFT of 300 days), second (approx. 260 of 460 days) and third (approx. 300 of at least 520 days) molars, and that the formation of this crown portion occurred largely after the teeth had already reached functional occlusion. By combining data on wear-related changes in crown morphology from the literature with the reconstructed additional investment into the crown base portion, it was possible to relate this additional investment to a prolongation of the functional periods of the molars ranging from 4 years in the M1 to 6 years in the M3. CONCLUSIONS: Our results allow to establish a quantitative link between an additional investment into molar crown growth of sheep and the extension of the functional period of these teeth. The reported findings enable an assessment of the adaptive value, in terms of increased longevity, of an additional investment into crown elongation in a mammalian herbivore.


Assuntos
Dente Molar/crescimento & desenvolvimento , Carneiro Doméstico/fisiologia , Coroa do Dente/crescimento & desenvolvimento , Animais , Esmalte Dentário , Feminino , Herbivoria , Masculino , Dente Molar/anatomia & histologia , Carneiro Doméstico/anatomia & histologia , Dente/anatomia & histologia
15.
Folia Med (Plovdiv) ; 60(2): 283-290, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30355817

RESUMO

BACKGROUND: The incisors and molars play a major role in the formation and function of permanent dentition. Much research has been devoted to investigating the eruption of teeth and their root development. AIM: To study the root development of permanent incisors and mandibular molars in correlation with treatment plan and proper treatment protocols. MATERIALS AND METHODS: The Demirjian's method was used to assess the root development of incisors and mandibular molars in children between 7 and 12 years old. RESULTS: In 7-year-old children most of the lower first mandibular molars (76%) had complete root length, but open apices. Eighty-two percent of the roots of the first mandibular molars of the 8-year-old children and 54% of these molars of the 9-year-old children were with open apices. The first mandibular molars had incomplete roots in the 10-year-olds (6%) and even in the 11-year-old children (4%). We detected Stage E in 32% of the 10-year-olds and in 24% of the 11-year-old children. Even in 12-year-old children we found Stage E in 4% of them from their panoramic X-rays. We detected complete root development in all of the children at the age of 12. CONCLUSIONS: Dental practitioners have to wait until the age of 10, 11 and even 12 to extract the first molars, when the furcation is formed. Proper clinical examination and diagnostic radiographs should be done before the beginning of the treatment of molars and incisors at the age between 7 and 12.


Assuntos
Dentição Permanente , Incisivo/crescimento & desenvolvimento , Dente Molar/crescimento & desenvolvimento , Raiz Dentária/crescimento & desenvolvimento , Criança , Protocolos Clínicos , Feminino , Humanos , Masculino , Mandíbula , Maxila , Extração Dentária
16.
Am J Hum Biol ; 30(5): e23163, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30129288

RESUMO

OBJECTIVES: Creating multi-tooth sequences of micro-sampled stable isotope (SI) analytical data can help track 20+ years of individual dietary history. Inferences about individual and population level behavioral patterns require cross-calibration of the timing of dietary changes recorded by each tooth. Dentin sections from contemporaneous tissues (eg, in M1 and M2) reflect dietary signature for the time of growth. Contemporary sections should produce similar values, allowing alignment of temporally overlapping portions of teeth into multi-tooth sequences. Published methods for determining the ages of incremental sections do not provide guidance for adjustment when poor alignment between individual tooth sequences is encountered. The primary objective is to address this problem; examine cause(s), assess the effects of the standard growth-model on available age-assessment techniques, and provide a viable solution. METHODS: Investigating difficulty in aligning a 3-molar sequence at Shamanka II, an Early Neolithic (7000-5700 BP) Kitoi hunter-gatherer cemetery in Cis-Baikal, Siberia, we employed 10 age assessment models and 13 variants of 2 published growth rate methods on 3 individuals of different age and sex. RESULTS: At Shamanka II, dentin initiation and/or growth rates were different from the mostly European, reference populations used to create published age-estimation/growth rate models. Initiation ages for M2 and M3 were delayed. Root formation rates were on the rapid end of known development parameters. CONCLUSIONS: Age-assessment methods customized to dentin initiation ages and growth parameters of Siberian populations produced a hybrid growth rate model for dentin section ages and improved alignment for multi-tooth SI sequences over published models.


Assuntos
Determinação da Idade pelos Dentes/métodos , Antropologia Física/métodos , Arqueologia/métodos , Dente Molar/química , Adolescente , Adulto , Isótopos de Carbono/análise , Feminino , Crescimento , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Dente Molar/crescimento & desenvolvimento , Isótopos de Nitrogênio/análise , Sibéria
17.
J Forensic Leg Med ; 58: 140-144, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29966814

RESUMO

Estimating chronological age accurately in young adults is difficult and additional methods are required to increase the accuracy. This study explored a new semi-automated method to assess shape change of third cervical vertebra (C3) with age in the living; comparing this as a method to determine whether individuals could be categorised into being less than 18 years of age (<18), or at least 18 years of age (≥18) with tooth formation of the second and third mandibular molars (M2 and M3). The sample was panoramic and lateral skull radiographs of 174 dental patients (78 males, 96 females aged 15-22 years). Twelve variables were compared in two age categories: younger than 18 and at least 18 years of age in males and females separately using a t-test. Tooth formation of M2 and M3 was assessed. Mean values of eight variables of C3 in males and one variable in females were significantly different between the two age categories (p < 0.05). Results for males showed that the best age indicator for age ≥18 was the ratio between height and width of C3 and for females, the ratio between diagonals. Results for molars showed that M2 was mature in 69% of males and 83% of females, within the expected age range of 14-16 years. M3 was highly variable ranging from stages 6-14 for both; M3 was missing in 24% of males and 28% of females and mature in 14% of males and 15% of females. The conclusion was that shape change of C3 has potential as an additional method to group individuals <18 and ≥ 18 years of age.


Assuntos
Determinação da Idade pelo Esqueleto/métodos , Determinação da Idade pelos Dentes/métodos , Vértebras Cervicais/crescimento & desenvolvimento , Dente Molar/crescimento & desenvolvimento , Adolescente , Vértebras Cervicais/diagnóstico por imagem , Estudos Transversais , Dentição Permanente , Feminino , Ciências Forenses/métodos , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Mandíbula , Dente Molar/diagnóstico por imagem , Radiografia Panorâmica , Coroa do Dente/diagnóstico por imagem , Coroa do Dente/crescimento & desenvolvimento , Raiz Dentária/diagnóstico por imagem , Raiz Dentária/crescimento & desenvolvimento , Adulto Jovem
18.
Biomed Res Int ; 2018: 2568235, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29854734

RESUMO

Aim: To assess the three-dimensional (3D) maxillomandibular and dental response to Balters Bionator (BB) and the Sander Bite Jumping Appliance (SBJA) in growing patients. Materials and Methods: Twenty-seven Class II division 1 patients (13 males, 14 females), consecutively treated with either the BB (9 females, 7 males; 10.1 ± 1.6 years) or SBJA (5 females, 6 males; 11 ± 1.9 years), were collected from a single orthodontic practice. All patients presented overjet ≥5 mm, full Class II or end-to-end molar relationship, mandibular retrusion. CBCT scans were available at T1 and after removal of the functional appliances (T2) with a mean interval of 18 months. The 3D location and direction of skeletal and dental changes with growth and treatment were quantitatively assessed. Statistical analysis was performed by means of Mann-Whitney U test (p < 0.05). Results: Patients treated with the SBJA and BB orthopedic appliances presented, respectively, 4.7 mm and 4.5 mm of 3D displacement of the chin, with marked ramus growth of, respectively, 3.7 mm and 2.3 mm. While the mandible and maxilla grew downward and forward, no opening of the mandible plane was observed. Both appliances adequately controlled labial inclination of lower incisors (1.3° and 0.3°, for the SBJA and BB groups, resp.). No significant between-group differences were found for the T2-T1 changes for any of the variables, with the exception of molar displacements (significantly greater in the SBJA group than in the BB group, 1.2 mm and 0.9 mm, resp.). Conclusions: The maxillomandibular and dental growth responses to BB and SBJA therapies are characterized by vertical ramus growth and elongation of mandible that improve the maxillomandibular relationship with adequate control of lower incisor position.


Assuntos
Força de Mordida , Técnicas de Fixação da Arcada Osseodentária/instrumentação , Mandíbula/diagnóstico por imagem , Retrognatismo/diagnóstico por imagem , Aparelhos Ativadores , Adolescente , Criança , Oclusão Dentária , Feminino , Humanos , Incisivo/diagnóstico por imagem , Incisivo/crescimento & desenvolvimento , Masculino , Mandíbula/crescimento & desenvolvimento , Dente Molar/diagnóstico por imagem , Dente Molar/crescimento & desenvolvimento , Retrognatismo/fisiopatologia
19.
J Histochem Cytochem ; 66(9): 663-671, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29676651

RESUMO

The clinical and pathological features of fluorosis are similar to amelogenesis imperfecta (AI) caused by FAM83H mutations, suggesting that excess fluoride could have effects on the expression of Fam83h. Our previous study found that Fam83h was downregulated by fluorosis induction in ameloblasts; the purpose of this study was to underline the importance of understanding the relationship between fluoride administration and Fam83h expression in vivo. A total of 80 healthy female adult Kunming mice were randomly divided into control group or F group that induced the clinical features of fluorosis. Immunohistochemical staining on sections of the embryo mandible regions was performed at different developmental stages. Mouse primary ameloblast-like cells of the two groups at E13.5, E15.5, and E18.5 were cultured and examined for the expression of Fam83h. The expression of Fam83h in the F group was significantly lower than that in the control group; however, Fam83h was observed clearly in the whole enamel organ in the control group. Our findings shed new light on the potential effects of Fam83h in fluorosis using a mouse model and revealed that high fluoride decreased the expression of Fam83h. This may be one of the reasons for the occurrence of fluorosis.


Assuntos
Fluorose Dentária/patologia , Dente Molar/patologia , Proteínas/análise , Ameloblastos/patologia , Amelogênese Imperfeita/patologia , Animais , Células Cultivadas , Feminino , Imuno-Histoquímica , Camundongos , Dente Molar/crescimento & desenvolvimento
20.
Sci Adv ; 4(4): eaar2334, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29651459

RESUMO

The detailed anatomical features that characterize fossil hominin molars figure prominently in the reconstruction of their taxonomy, phylogeny, and paleobiology. Despite the prominence of molar form in human origins research, the underlying developmental mechanisms generating the diversity of tooth crown features remain poorly understood. A model of tooth morphogenesis-the patterning cascade model (PCM)-provides a developmental framework to explore how and why the varying molar morphologies arose throughout human evolution. We generated virtual maps of the inner enamel epithelium-an indelibly preserved record of enamel knot arrangement-in 17 living and fossil hominoid species to investigate whether the PCM explains the expression of all major accessory cusps. We found that most of the variation and evolutionary changes in hominoid molar morphology followed the general developmental rule shared by all mammals, outlined by the PCM. Our results have implications for the accurate interpretation of molar crown configuration in hominoid systematics.


Assuntos
Modelos Biológicos , Dente Molar/anatomia & histologia , Dente Molar/crescimento & desenvolvimento , Dente/anatomia & histologia , Dente/crescimento & desenvolvimento , Animais , Evolução Biológica , Biomarcadores , Fósseis , Expressão Gênica , Humanos , Mamíferos
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