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1.
Niger J Clin Pract ; 23(4): 456-463, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32246650

RESUMO

Aims: The purpose of this study was to observe the stresses of all-on-four implant designs in an edentulous mandible in the implant, surrounding bone, and monolithic ceramics. Materials and Methods: In mandibular all-on-four implant models, anterior implants were placed vertically, and posterior implants were differently inclined. On the full-arch fixed prosthetic restoration monolithic zirconia framework, monolithic lithium disilicate was prepared as the superstructure. Model 1M (1M-15.5); posterior implants angled at 15° to the occlusion plane and a cantilever length of 5 mm, Model 2M; (2M-15.9), Model 3M; (3M-30.5), and Model 4M; (4M-30.9) were prepared. A total of 300 N bilateral force was applied at an angle of 30° and oblique to the occlusion plane. Stress values on dental implants, abutments, the surrounding bone, and prosthetic restorations were calculated. Results: The highest stress concentration was observed in the 2nd connector region between the canine and the 1st premolar tooth in the monolithic zirconia frameworks (457.21 MPa). Stress concentration in the cortical bone was 60.93 MPa in posterior implants. Stress was higher in posterior angled implants than straight implants. Stress at posterior angulation increased by 21 MPa in implants angled at 15°. Conclusion: In bilateral loading, the force applied to anterior implants does not have a significant effect on the bone structure. Stress concentration increases in posterior angled implants and surrounding bone. Moreover, stress concentration increases as the length of the cantilever, the weakest part in all-on-four implants, increases. As posterior implant angulation increases, stress concentration level and localization are affected.


Assuntos
Cerâmica/química , Implantes Dentários , Prótese Dentária Fixada por Implante/métodos , Imageamento Tridimensional/métodos , Titânio/química , Zircônio/química , Dente Pré-Molar , Arco Dental/fisiologia , Modelos Dentários , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Mandíbula/fisiologia , Estresse Mecânico
2.
Comput Methods Biomech Biomed Engin ; 23(9): 445-455, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32116047

RESUMO

The location of the terminal hinge axis of the temporomandibular joint is still a very wide-spread procedure in dentistry in order to replicate the movement in various articulator devices. Especially pantographic methods are claimed to provide accurate measurements and, additionally, are seen to be able to separate a pure rotation of the joint from a movement with an arbitrary combined shift and rotation. In the latter application, these methods were used in a lot of studies as a reference standard. The aim of this study was to analyze, whether common pantographic methods in general are able to distinguish between a pure rotation and a movement with rotational and translational portions. The mathematical proof of this analysis was done with theoretical kinematic considerations and compared with computer simulations. The results show for the first time that there exist combinations of rotational and translational movements of the temporomandibular joint which cannot be separated from pure rotational movements using actual pantographic methods. Even more, the consequence is a shifted location of the (combined) finite center (axis) of rotation in comparison to the true center (axis) of rotation: in case of a translational portion of only 1 mm, this is a displacement of around ±6 mm and, in case of 2 mm translation, a displacement of ±12 mm. This finding necessitates a critical reinterpretation of former studies using pantographic methods as a reference standard. Further, under some circumstances it may also affect the applicability of articulator concepts and the interpretation of functional signs.


Assuntos
Rotação , Articulação Temporomandibular/fisiologia , Fenômenos Biomecânicos , Simulação por Computador , Humanos , Mandíbula/fisiologia , Movimento
3.
Comput Methods Biomech Biomed Engin ; 23(7): 261-270, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31965827

RESUMO

Computational models of the masticatory system can provide estimates of occlusal loading during (static) biting or (dynamic) chewing and therefore can be used to evaluate and optimize functional performance of prosthodontic devices and guide dental surgery planning. The modelling assumptions, however, need to be chosen carefully in order to obtain meaningful predictions. The objectives of this study were two-fold: (i) develop a computational model to calculate the stress response of the first molar during biting of a rubber sample and (ii) evaluate the influence of different occlusal load models on the stress response of dental structures. A three-dimensional finite element model was developed comprising the mandible, first molar, associated dental structures, and the articular fossa and discs. Simulations of a maximum force bite on a rubber sample were performed by applying muscle forces as boundary conditions on the mandible and computing the contact between the rubber and molars (GS case). The molar occlusal force was then modelled as a single point force (CF1 case), four point forces (CF2 case), and as a sphere compressing against the occlusal surface (SL case). The peak enamel stress for the GS case was 110 MPa and 677 MPa, 270 MPa and 305 MPa for the CF1, CF2 and SL cases, respectively. Peak dentin stress for the GS case was 44 MPa and 46 MPa, 50 MPa and 63 MPa for the CF1, CF2 and SL cases, respectively. Furthermore, the enamel stress distribution was also strongly correlated to the occlusal load model. The way in which occlusal load is modelled has a substantial influence on the stress response of enamel during biting, but has relatively little impact on the behavior of dentin. The use of point forces or sphere contact to model occlusal loading during mastication overestimates enamel stress magnitude and also influences enamel stress distribution.


Assuntos
Simulação por Computador , Oclusão Dentária , Análise do Estresse Dentário , Mastigação/fisiologia , Dente/patologia , Adulto , Fenômenos Biomecânicos , Força de Mordida , Análise de Elementos Finitos , Humanos , Masculino , Mandíbula/fisiologia , Estresse Mecânico
4.
PLoS One ; 14(12): e0226205, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31809528

RESUMO

Kynurenic acid (KYNA) is a neuroactive metabolite of tryptophan. KYNA naturally occurs in breast milk and its content increases with lactation, indicating the role of neonatal nutrition in general growth with long-term health effects. KYNA is also an antagonist of ionotropic glutamate receptors expressed in bone cells. The aim of this study was to establish the effects of chronic KYNA supplementation on bone homeostasis in young rats, using mandible as a model bone. Female and male newborn Wistar rats were divided into control and KYNA-administered groups until 60 days of age (25x101 mg/L or 25x102 mg/L in drinking water). Hemimandibles were subjected to densitometry, computed tomography analysis and mechanical testing. Rats supplemented with KYNA at both doses showed a decrease in body weight. There were no effects of KYNA administration and mandible histomorphometry. In males, a significant quadratic effect (P < 0.001) was observed in the densitometry of the hemimandible, where BMD increased in the group supplemented with 2.5x101 mg/L of KYNA. Analysis of mechanical tests data showed that when fracture forces were corrected for bone geometry and rats body weight the improvement of bone material properties was observed in male and female rats supplemented with lower dose of KYNA. This study showed that chronic supplementation with KYNA may limit weight gain in the young, without adversely affecting the development of the skeleton.


Assuntos
Ácido Cinurênico/administração & dosagem , Mandíbula/fisiologia , Perda de Peso/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Fenômenos Biomecânicos/efeitos dos fármacos , Densidade Óssea/efeitos dos fármacos , Estudos de Casos e Controles , Suplementos Nutricionais , Feminino , Ácido Cinurênico/farmacologia , Masculino , Mandíbula/efeitos dos fármacos , Ratos , Ratos Wistar , Tomografia Computadorizada por Raios X
5.
PLoS One ; 14(12): e0226949, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31881075

RESUMO

Morphological convergence is an intensely studied macroevolutionary phenomenon. It refers to the morphological resemblance between phylogenetically distant taxa. Currently available methods to explore evolutionary convergence either: rely on the analysis of the phenotypic resemblance between sister clades as compared to their ancestor, fit different evolutionary regimes to different parts of the tree to see whether the same regime explains phenotypic evolution in phylogenetically distant clades, or assess deviations from the congruence between phylogenetic and phenotypic distances. We introduce a new test for morphological convergence working directly with non-ultrametric (i.e. paleontological) as well as ultrametric phylogenies and multivariate data. The method (developed as the function search.conv within the R package RRphylo) tests whether unrelated clades are morphologically more similar to each other than expected by their phylogenetic distance. It additionally permits using known phenotypes as the most recent common ancestors of clades, taking full advantage of fossil information. We assessed the power of search.conv and the incidence of false positives by means of simulations, and then applied it to three well-known and long-discussed cases of (purported) morphological convergence: the evolution of grazing adaptation in the mandible of ungulates with high-crowned molars, the evolution of mandibular shape in sabertooth cats, and the evolution of discrete ecomorphs among anoles of Caribbean islands. The search.conv method was found to be powerful, correctly identifying simulated cases of convergent morphological evolution in 95% of the cases. Type I error rate is as low as 4-6%. We found search.conv is some three orders of magnitude faster than a competing method for testing convergence.


Assuntos
Evolução Biológica , Algoritmos , Animais , Gatos/anatomia & histologia , Gatos/genética , Gatos/fisiologia , Fósseis , Lagartos/anatomia & histologia , Lagartos/genética , Lagartos/fisiologia , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Fenótipo , Filogenia , Índias Ocidentais
6.
PLoS One ; 14(12): e0221137, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31877131

RESUMO

The curved planes of the human dentition seen in the sagittal view, the mandibular curve of Spee and the maxillary compensating curve, have clinical importance to modern dentistry and potential relevance to the craniofacial evolution of hominins. However, the mechanism providing the formation of these curved planes is poorly understood. To explore this further, we use a simplified finite element model, consisting of maxillary and mandibular "blocks", developed to simulate tooth eruption, and forces opposing eruption, during simplified masticatory function. We test our hypothesis that curved occlusal planes develop from interplay between tooth eruption, occlusal load, and mandibular movement. Our results indicate that our simulation of rhythmic chewing movement, tooth eruption, and tooth eruption inhibition, applied concurrently, results in a transformation of the contacting maxillary and mandibular block surfaces from flat to curved. The depth of the curvature appears to be dependent on the radius length of the rotating (chewing) movement of the mandibular block. Our results suggest mandibular function and maxillo-mandibular spatial relationship may contribute to the development of human occlusal curvature.


Assuntos
Mandíbula/fisiologia , Erupção Dentária/fisiologia , Dente/fisiologia , Evolução Biológica , Dentição , Análise de Elementos Finitos , Humanos , Mastigação/fisiologia , Maxila/fisiologia
7.
PLoS One ; 14(10): e0224480, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31648278

RESUMO

Detailed knowledge of age-related changes in the structure and mineralization of bones is important for interpreting osseous changes in wild mammals caused by exposure to environmental contaminants. This study analyzed mandibular size, microarchitecture and volumetric bone mineral density (vBMD) in harbor seals (n = 93, age range 0.5 months to 25 years) from the German North Sea. Bone microarchitecture and vBMD were assessed using high-resolution peripheral quantitative computed tomography (HR-pQCT). Significant differences were observed between the analyzed age classes (i) young juveniles (0.5-10 months), (ii) yearlings (12-23 months), and (iii) adults (12-25 years) for several of the variables, indicating an overall increase in cortical and trabecular area, cortical thickness and total and cortical vBMD with age. Furthermore, for juvenile animals (≤ 23 months), significant positive correlations with age were observed for mandible length and perimeter, cortical area, cortical thickness, trabecular separation, and total and cortical vBMD. The findings demonstrate a rapid increase in overall size, cortical dimensions and the degree of mineralization of the harbor seal mandible during the first two years after birth. Negative correlations with age existed for trabecular number and thickness as well as for trabecular bone volume fraction in the juveniles. The findings suggest a reduction in trabecular bone volume fraction with age, due to the bone trabeculae becoming thinner, less numerous and more widely spaced. Given the strong age dependence of most analyzed parameters, it is recommended to standardize samples with respect to age in future studies comparing microarchitecture and mineralization of harbor seal mandibles from different populations or different collection periods.


Assuntos
Envelhecimento/fisiologia , Densidade Óssea/fisiologia , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Phoca , Animais , Tamanho do Órgão
8.
Homo ; 70(1): 15-30, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31475290

RESUMO

Recent studies indicate that evolution of the craniofacial skeleton is influenced by dietary behavior, which in turn alters masticatory efficacy and temporomandibular joint (TMJ) stability. In this study the mechanical properties of the masticatory system and the integrity of the TMJ in human populations from Northern China, dated to between 3800 BCE and 100 CE, were assessed. The results demonstrate that the mechanical efficiency is comparable to other modern human populations, though variations are present across different populations. While the ratio of overall weighted muscle efficiency for incisor loading vs. molar loading in pastoral and some recent agricultural groups is similar to early Homo sapiens, the ratio in more ancient agricultural groups is similar to the ratio in populations with heavy anterior paramasticatory activities, such as Neandertals, Inuits, and Native Americans. The TMJ vulnerability negatively correlates with the maxillary dental arch size, and positively with the condylar size. These findings suggest that there are multi-directional strategies in adaptation to heavy anterior teeth loading, such as increasing anterior teeth loading efficiency, increasing facial height, increasing facial breath and facial orthognathy, or decreasing anterior facial length. Furthermore, populations or individuals with a smaller dental arch and high biting efficiency could more easily injure the TMJ during unilateral loadings, which may explain the higher prevalence of TMJ disorders in modern humans, especially in women. These findings further reflect the impact of diachronic changes of the masticatory apparatus and lifestyle and their impact on oral health during recent human history.


Assuntos
Mandíbula , Mastigação/fisiologia , Crânio , Articulação Temporomandibular , Dente , Adulto , Evolução Biológica , Fenômenos Biomecânicos/fisiologia , China , Feminino , Fósseis , História Antiga , Humanos , Masculino , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Crânio/anatomia & histologia , Crânio/fisiologia , Articulação Temporomandibular/anatomia & histologia , Articulação Temporomandibular/fisiologia , Dente/anatomia & histologia , Dente/fisiologia
9.
Rev. Bras. Saúde Mater. Infant. (Online) ; 19(3): 621-630, Jul.-Sept. 2019. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1041089

RESUMO

Abstract Objectives: To investigate full term newborns suction pattern in non-nutritive suction and their feeding performance. Methods: An analytical descriptive study was carried out from November 2016 to March 2017, with 50 dyads mothers/newborns through the non-nutritive suction evaluation and a direct observation on the newborn's performance on feeding. The data were distributed through simple and relative frequencies (percentages) when categorical or by mean, maximum, minimum and the standard deviation when is continuous, discrete or ordinal. To evaluate the mean differences, the Student's t test was used with significance level of 5%. Results: There were significant differences among the newborn's mandible movement ("newborn's mouth slightly open" p=0,005), suction ("cheek strain during feeding" p<0,001) and dyad mother and newborn positioning ("breasts supported with fingers on the areola" p=0,041 and baby's neck or trunk turned" p=0,041). Conclusions: Newborns that presented changes in their mandible movement on the Non-Nutritive Suction (NNS) also presented difficulties in feeding. The newborn's knowledge on suction pattern through the NNS has proven to be an important strategy that may help identify possible difficulties during feeding.


Resumo Objetivos: investigar o padrão de sucção de recém-nascidos a termo na sucção não-nutritiva e sua relação com o desempenho destes na mamada. Métodos: estudo descritivo analítico, realizado de novembro de 2016 a março de 2017, com 50 díades mãe/recém-nascido, mediante avaliação da sucção não-nutritiva e observação direta do desempenho do recém-nascido na mamada. Os dados foram descritos por meio de frequências simples e relativas (percentuais) quando categóricas ou média, máximo, mínimo e desvio padrão quando contínuas, discretas ou ordinais. Para avaliar diferenças de média foi utilizado o teste T de Student com nível de significância de 5%. Resultados: houve diferenças significativas entre movimentação da mandíbula do recém-nascido e aspectos da pega ("boca do bebê pouco aberta" p=0,005), sucção ("esforço da bochecha durante a mamada" p<0,001) e posicionamento da díade mãe e recém-nascido ("mamas apoiadas com os dedos na aréola" p=0,041 e bebê com pescoço ou tronco torcidos" p=0,041). Conclusões: recém-nascidos que apresentaram alterações na movimentação da mandíbula na Sucção Não Nutritiva (SNN) tiveram também dificuldade na realização da mamada. O conhecimento do padrão de sucção do recém-nascido, através da avaliação da SNN mostrou-se como estratégia importante que pode auxiliar na identificação de possíveis dificuldades do recém-nascido durante a mamada.


Assuntos
Humanos , Recém-Nascido , Comportamento de Sucção , Sucção , Aleitamento Materno , Nascimento a Termo , Sistema Estomatognático , Saúde Materno-Infantil , Mandíbula/fisiologia , Leite Humano
10.
Nat Commun ; 10(1): 3571, 2019 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395864

RESUMO

Oral biofilm accumulation in pets is a growing concern. It is desirable to address this problem via non-invasive teeth cleaning techniques, such as through friction between teeth and food during chewing. Therefore, pet food design tools are needed towards optimising cleaning efficacy. Developing such tools is challenging, as several parameters affecting teeth cleaning should be considered: the food's complex mechanical response, the contacting surfaces topology as well as the wide range of masticatory and anatomical characteristics amongst breeds. We show that Finite Element (FE) models can efficiently account for all these parameters, through the simulation of food deformation and fracture during the first bite. This reduces the need for time consuming and costly in-vivo or in-vitro trials. Our in-silico model is validated through in-vitro tests, demonstrating that the initial oral processing stage can be engineered through computers with high fidelity.


Assuntos
Ração Animal , Bioengenharia/métodos , Mastigação/fisiologia , Higiene Bucal/veterinária , Animais de Estimação/fisiologia , Animais , Biofilmes/crescimento & desenvolvimento , Gatos/microbiologia , Gatos/fisiologia , Simulação por Computador , Cães/microbiologia , Cães/fisiologia , Análise de Elementos Finitos , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Maxila/anatomia & histologia , Maxila/fisiologia , Modelos Biológicos , Animais de Estimação/microbiologia , Dente/anatomia & histologia , Dente/microbiologia , Dente/fisiologia
11.
J Manipulative Physiol Ther ; 42(4): 267-275, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31262580

RESUMO

OBJECTIVE: The purpose of this study was to propose a quantitative evaluation for mandibular opening-closing movement asymmetries and to verify the intraexaminer and interexaminer reliability using photogrammetry in individuals with and without myogenic temporomandibular disorders. METHODS: Forty-nine female participants between ages 18 and 40 were enrolled in this study. They were assigned to 2 different groups: a temporomandibular disorder group, (n = 25; 28.1 ± 3.6 years) and an asymptomatic group (n = 24; 25.6 ± 5.1 years). Data were collected through photogrammetry using Corel Draw X3 software (Corel Corp, Ottawa, Ontario, Canada) for angle measurements. Reliability analysis was done on the total sample, and the photographs were obtained by a singular examiner on 2 occasions (intraexaminer) 1 month apart and from measurement made by another examiner (interexaminer) on different days. The intraclass correlation coefficient (ICC) was applied with a significance level of 5%. RESULTS: The photogrammetry had excellent intrarater and inter-rater reliability for the evaluation of opening and closing movements of the jaw (intrarater: opening ICC = 0.99; closing ICC = 0.98; inter-rater: opening ICC = 0.89 and closing ICC = 0.82). Photogrammetry also demonstrated excellent intra- and inter-rater reliability in the evaluation of head posture (intra-rater: head deviation ICC = 0.96; head position ICC = 0.75; inter-rater: head deviation ICC = 0.98; head position ICC = 0.98). CONCLUSION: Under these experimental conditions, most angular values presented excellent intra- and interexaminer reliability.


Assuntos
Mandíbula/fisiologia , Fotogrametria , Amplitude de Movimento Articular/fisiologia , Transtornos da Articulação Temporomandibular/fisiopatologia , Articulação Temporomandibular/fisiologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Reprodutibilidade dos Testes
12.
Med Sci Monit ; 25: 3933-3940, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31131833

RESUMO

BACKGROUND The purpose of this study was to assess the effect of different exposure levels of a dental implant's first thread on adjacent bone stress and strain using the finite element analysis method. MATERIAL AND METHODS Three-dimensional models of 2 threaded implants and abutments with a mandibular bone segment were constructed to represent the covered (C) and exposed models. In the exposed models, the implant was first placed in the bone, and rotated around its axis a quarter-turn each time to simulate 4 different levels of first thread exposure at the mid-lingual side: Upper Flank (UF), Thread Crest (TC), Lower Flank (LF), and Thread Root (TR) models. Oblique forces were applied and analysis was performed. RESULTS Maximum compressive stress magnitude and distribution varied according to the exposed thread profile. In the exposed group, peak stress ranged from 136 MPa to 197 MPa in TC and LF models, respectively, compared to 141 MPa in C model. In LF, UF, and C models, peak stress was observed at the mid-lingual side of the crestal region, while in TC and TR models, peak stress shifted distally in accordance with thread profile. However, alveolar bone volumes which exhibited compressive microstrain levels within the physiological loading and maintenance windows were relatively close in all models. CONCLUSIONS Results suggest that the exposed thread profile influences stress and strain outcomes in the adjacent bone; however, this influence is only limited to a small region around the exposed thread.


Assuntos
Implantes Dentários/efeitos adversos , Análise do Estresse Dentário/métodos , Fenômenos Biomecânicos/fisiologia , Simulação por Computador , Planejamento de Prótese Dentária , Módulo de Elasticidade , Análise de Elementos Finitos , Mandíbula/fisiologia , Software , Estresse Mecânico
13.
Biomed Eng Online ; 18(1): 59, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31096969

RESUMO

BACKGROUND: Mastication is one of the most fundamental functions for the conservation of life. The demand for devices for evaluating stomatognathic function, for instance, recording mandibular movements or masticatory muscle activities using animal models, has been increasing in recent years to elucidate neuromuscular control mechanisms of mastication and to investigate the etiology of oral motor disorders. To identify the fundamental characteristics of the jaw movements of mice, we developed a new device that reconstructs the three-dimensional (3D) movement trajectories on an arbitrary point on the mandible during mastication. METHODS: First, jaw movements with six degrees of freedom were measured using a motion capture system comprising two high-speed cameras and four reflective markers. Second, a 3D model of the mandible including the markers was created from micro-computed tomography images. Then, the jaw movement trajectory on the certain anatomical point was reproduced by integrating the kinematic data of the jaw movements with the geometric data of the mandible. RESULTS: The 3D movements at any points on the mandible, such as the condyle, molar, and incisor during mastication, could be calculated and visualized with an accuracy > 0.041 mm in 3D space. The masticatory cycle was found to be clearly divided into three phases, namely, the opening, closing, and occlusal phases in mice. CONCLUSIONS: The proposed system can reproduce and visualize the movements of internal anatomical points such as condylar points precisely by combining kinematic data with geometric data. The findings obtained from this system could facilitate our understanding of the pathogenesis of eating disorders or other oral motor disorders when we could compare the parameters of stomatognathic function of normal mice and those of genetically modified mice with oral behavioral dysfunctions.


Assuntos
Imageamento Tridimensional , Mandíbula/diagnóstico por imagem , Mandíbula/fisiologia , Movimento , Microtomografia por Raio-X , Animais , Fenômenos Biomecânicos , Camundongos
14.
Med Sci Monit ; 25: 3503-3509, 2019 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-31079139

RESUMO

BACKGROUND The aim of this retrospective study was to compare the measurements of bone mineral density (BMD) combined with volumetric dental tomography measurements taken from three main regions selected on the lower mandible, the right mandibular, medial mandibular, and left mandibular regions, in patients with ectodermal dysplasia and age-matched and gender-matched controls. Measurement of BMD in Hounsfield units (HUs) were evaluated using three-dimensional (3D) cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS Mandibular bone tomography images were evaluated from 9 women and 5 men diagnosed with ectodermal dysplasia and a control group of 9 women and 5 men. The HU values obtained according to age and gender of the total 28 study participants were measured. Statistical analysis of the data used Student's t-test. RESULTS BMD in the ectodermal dysplasia group was significantly lower compared with the BMD in the control group. Comparison of the left and right mandibular angulus regions showed that the BMD of patients with ectodermal dysplasia was significantly lower when compared with the control group in both regions, but no significant difference was found between the two groups in the BMD of the central mandibular region. CBCT was found to be an effective method for the measurement of BMD. CONCLUSIONS In patients with ectodermal dysplasia, reduced BMD should be taken into consideration when planning surgical interventions involving bone tissue and when planning implant surgery. The results of this study may be of value in dentistry and other fields of medicine.


Assuntos
Densidade Óssea/fisiologia , Tomografia Computadorizada de Feixe Cônico/métodos , Displasia Ectodérmica/fisiopatologia , Adolescente , Adulto , Criança , Feminino , Humanos , Masculino , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Estudos Retrospectivos , Turquia , Adulto Jovem
15.
PLoS One ; 14(4): e0214510, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30995252

RESUMO

There is considerable debate regarding whether mandibular morphology in ungulates primarily reflects phylogenetic affinities or adaptation to specific diet. In an effort to help resolve this debate, we use three-dimensional finite element analysis (FEA) to assess the biomechanical performance of mandibles in eleven ungulate taxa with well-established but distinct dietary preferences. We found notable differences in the magnitude and the distribution of von Mises stress between Artiodactyla and Perissodactyla, with the latter displaying lower overall stress values. Additionally, within the order Artiodactyla the suborders Ruminantia and Tylopoda showed further distinctive stress patterns. Our data suggest that a strong phylogenetic signal can be detected in biomechanical performance of the ungulate mandible. In general, Perissodactyla have stiffer mandibles than Artiodactyla. This difference is more evident between Perissodactyla and ruminant species. Perissodactyla likely rely more heavily on thoroughly chewing their food upon initial ingestion, which demands higher bite forces and greater stress resistance, while ruminants shift comminution to a later state (rumination) where less mechanical effort is required by the jaw to obtain sufficient disintegration. We therefore suggest that ruminants can afford to chew sloppily regardless of ingesta, while hindgut fermenters cannot. Additionally, our data support a secondary degree of adaptation towards specific diet. We find that mandibular morphologies reflect the masticatory demands of specific ingesta within the orders Artiodactyla and Perissodactyla. Of particular note, stress patterns in the white rhinoceros (C. simum) look more like those of a general grazer than like other rhinoceros' taxa. Similarly, the camelids (Tylopoda) appear to occupy an intermediate position in the stress patterns, which reflects the more ancestral ruminating system of the Tylopoda.


Assuntos
Força de Mordida , Mandíbula/fisiologia , Mastigação/fisiologia , Ruminantes/fisiologia , Animais , Artiodáctilos/anatomia & histologia , Fenômenos Biomecânicos , Análise por Conglomerados , Dieta , Evolução Molecular , Feminino , Análise de Elementos Finitos , Imageamento Tridimensional , Masculino , Modelos Anatômicos , Perissodáctilos/anatomia & histologia , Filogenia , Reprodutibilidade dos Testes , Especificidade da Espécie
16.
Nat Commun ; 10(1): 1703, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30979871

RESUMO

Multiple vertebrate embryonic structures such as organ primordia are composed of confluent cells. Although mechanisms that shape tissue sheets are increasingly understood, those which shape a volume of cells remain obscure. Here we show that 3D mesenchymal cell intercalations are essential to shape the mandibular arch of the mouse embryo. Using a genetically encoded vinculin tension sensor that we knock-in to the mouse genome, we show that cortical force oscillations promote these intercalations. Genetic loss- and gain-of-function approaches show that Wnt5a functions as a spatial cue to coordinate cell polarity and cytoskeletal oscillation. These processes diminish tissue rigidity and help cells to overcome the energy barrier to intercalation. YAP/TAZ and PIEZO1 serve as downstream effectors of Wnt5a-mediated actomyosin polarity and cytosolic calcium transients that orient and drive mesenchymal cell intercalations. These findings advance our understanding of how developmental pathways regulate biophysical properties and forces to shape a solid organ primordium.


Assuntos
Polaridade Celular , Citoesqueleto/fisiologia , Mandíbula/embriologia , Mandíbula/fisiologia , Proteína Wnt-5a/fisiologia , Citoesqueleto de Actina , Actomiosina/metabolismo , Animais , Cálcio/metabolismo , Ciclo Celular , Citosol/metabolismo , Elasticidade , Células Epiteliais/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Mutação , Oscilometria , Transdução de Sinais , Estresse Mecânico , Vinculina/metabolismo , Viscosidade
17.
Artif Cells Nanomed Biotechnol ; 47(1): 1577-1584, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31027424

RESUMO

Bone tissue engineering is an area of regenerative medicine that attempts to repair bone defects. Seed cells such as dental pulp stem cells (DPSCs) and adipose tissue-derived stem cells (ADSCs) are two of the most well-characterized cells for bone regeneration because their use involves few ethical constraints and they have the ability to differentiate into multiple cell types, secreting growth factors and depositing mineral. However, bone regeneration ability of these cells remains unclear. This study aimed to compare the bone formation capacity of DPSCs and ADSCs in vitro and in vivo. Studies revealed that DPSCs had enhanced colony-forming ability, higher proliferative ability, stronger migration ability and higher expression of angiogenesis-related genes. They also secreted more vascular endothelial growth factor compared to ADSCs. In contrast, ADSCs grew more slowly compared to DPSCs but exhibited greater osteogenic differentiation potential, higher expression of osteoblast marker genes, and greater mineral deposition. Furthermore, after DPSCs and ADSCs were implanted into a mandibular defect of a rat for 6 weeks, ADSCs showed visible bone tissue as early as week 1 and promoted faster and greater bone regeneration compared to the DPSC group. These results suggest that ADSCs might be more useful than DPSCs for bone regeneration.


Assuntos
Tecido Adiposo/citologia , Regeneração Óssea , Polpa Dentária/citologia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Animais , Calcificação Fisiológica , Diferenciação Celular , Proliferação de Células , Regulação da Expressão Gênica , Humanos , Mandíbula/citologia , Mandíbula/metabolismo , Mandíbula/fisiologia , Neovascularização Fisiológica , Osteogênese , Ratos , Fator A de Crescimento do Endotélio Vascular/metabolismo
18.
Plast Reconstr Surg ; 143(5): 1408-1419, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31033822

RESUMO

BACKGROUND: Autologous bone grafts remain a standard of care for the reconstruction of large bony defects, but limitations persist. The authors explored the bone regenerative capacity of customized, three-dimensionally printed bioactive ceramic scaffolds with dipyridamole, an adenosine A2A receptor indirect agonist known to enhance bone formation. METHODS: Critical-size bony defects (10-mm height, 10-mm length, full-thickness) were created at the mandibular rami of rabbits (n = 15). Defects were replaced by a custom-to-defect, three-dimensionally printed bioactive ceramic scaffold composed of ß-tricalcium phosphate. Scaffolds were uncoated (control), collagen-coated, or immersed in 100 µM dipyridamole. At 8 weeks, animals were euthanized and the rami retrieved. Bone growth was assessed exclusively within scaffold pores, and evaluated by micro-computed tomography/advanced reconstruction software. Micro-computed tomographic quantification was calculated. Nondecalcified histology was performed. A general linear mixed model was performed to compare group means and 95 percent confidence intervals. RESULTS: Qualitative analysis did not show an inflammatory response. The control and collagen groups (12.3 ± 8.3 percent and 6.9 ± 8.3 percent bone occupancy of free space, respectively) had less bone growth, whereas the most bone growth was in the dipyridamole group (26.9 ± 10.7 percent); the difference was statistically significant (dipyridamole versus control, p < 0.03; dipyridamole versus collagen, p < 0.01 ). There was significantly more residual scaffold material for the collagen group relative to the dipyridamole group (p < 0.015), whereas the control group presented intermediate values (nonsignificant relative to both collagen and dipyridamole). Highly cellular and vascularized intramembranous-like bone healing was observed in all groups. CONCLUSION: Dipyridamole significantly increased the three-dimensionally printed bioactive ceramic scaffold's ability to regenerate bone in a thin bone defect environment.


Assuntos
Agonistas do Receptor A2 de Adenosina/farmacologia , Dipiridamol/farmacologia , Traumatismos Mandibulares/cirurgia , Reconstrução Mandibular/métodos , Tecidos Suporte/química , Animais , Regeneração Óssea/efeitos dos fármacos , Cerâmica/química , Cerâmica/uso terapêutico , Colágeno/química , Colágeno/uso terapêutico , Modelos Animais de Doenças , Humanos , Mandíbula/diagnóstico por imagem , Mandíbula/patologia , Mandíbula/fisiologia , Traumatismos Mandibulares/diagnóstico por imagem , Traumatismos Mandibulares/patologia , Impressão Tridimensional , Coelhos , Resultado do Tratamento , Microtomografia por Raio-X
19.
J Craniofac Surg ; 30(4): e293-e295, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30908434

RESUMO

The aim of this study was to compare, in vitro, the mechanical resistance to vertical displacement of the mandible after osteotomy for lateralization of the inferior alveolar nerve and installation of dental implants. One hundred eighty polyurethane mandibles were equally divided into 6 groups: G1-intact hemi-mandibles (control group), G2-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve, G3-hemi-mandibles with installation of 3 bicortical dental implants (3.75 × 13 mm), G4-hemi-mandibles with installation of 3 dental implants that did not reach the basal cortical bone (3.75 × 11 mm), G5-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve and installation of 3 bicortical dental implants (3.75 × 13 mm) and G6-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve and installation of 3 dental implants that did not reach the basal cortical bone (3.75 × 11 mm). The specimens were subjected to linear loading tests. The highest mean value of maximum load was found in G1 (412.36N ±â€Š11.99), followed by G2 (396.87N ±â€Š23.94), G3 (319.63N ±â€Š57.28), G4 (303.34N ±â€Š18.25), G5 (231.75N ±â€Š63.64) and G6 (228.13N ±â€Š20.75). Based on this data, it can be concluded that the bicorticalization (or not) of the implants was not a statistically significant risk factor for the vertical displacement of polyurethane hemi-mandibles.


Assuntos
Implantes Dentários/efeitos adversos , Mandíbula , Fraturas Mandibulares , Nervo Mandibular/fisiologia , Osteotomia , Fenômenos Biomecânicos , Humanos , Mandíbula/inervação , Mandíbula/fisiologia , Mandíbula/cirurgia , Fraturas Mandibulares/epidemiologia , Fraturas Mandibulares/fisiopatologia , Modelos Biológicos , Osteotomia/efeitos adversos , Osteotomia/estatística & dados numéricos
20.
Am J Orthod Dentofacial Orthop ; 155(3): 388-397, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30826042

RESUMO

INTRODUCTION: The aim of this finite element study was to analyze and clarify the mechanics of tooth movement patterns for total distalization of the mandibular dentition based on force angulation. METHODS: Long-term orthodontic movement of the mandibular dentition was simulated by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. RESULTS: Displacement of each tooth was caused by movement of the whole dentition, elastic deflection of the archwire, and clearance gap between the archwire and bracket slot. The whole dentition was rotated clockwise or counterclockwise when the line of action of the force passed below or above the center of resistance. Elastic deflection of the archwire induced a lingual tipping of the anterior teeth. It became larger when increasing the magnitude of angulation. The archwire could be rotated within the clearance gap between the archwire and the bracket slot, and thereby the teeth tipped. CONCLUSIONS: Mechanics of total mandibular distalization was clarified. Selective use of force angulation with a careful biomechanical understanding can achieve proper distalization of the whole mandibular dentition.


Assuntos
Análise de Elementos Finitos , Má Oclusão de Angle Classe III/terapia , Mandíbula/fisiologia , Técnicas de Movimentação Dentária , Processo Alveolar/fisiologia , Fenômenos Biomecânicos , Módulo de Elasticidade , Humanos , Braquetes Ortodônticos , Fios Ortodônticos , Ligamento Periodontal/fisiologia
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