Aims: To determine improvements in third metacarpal (Mc3) condylar microanatomy attributable to preconditioning exercise. To investigate developmental causes of Mc3 condylar fracture. Methods: Twelve Thoroughbred horses were raised at pasture; six received preconditioning exercise from 10 days. Calcein labels were administered 19 and 11 days prior to euthanasia at 18 months. Six horses also received 2 seasons of race-training and were euthanised at 3 years. Slices were taken from the distal Mc3 condyle in the frontal and dorsal- and palmar-oblique frontal planes, scanned with DXA and macerated (frontal slices) or embedded in PMMA (oblique slices). Articular calcified cartilage (ACC) and subchondral bone (SCB) in oblique slices were imaged using confocal scanning light microscopy and quantitative backscattered electron scanning electron microscopy. ACC and SCB in the palmar slice lateral parasagittal grooves were imaged using μCT and nanoindentation tested. Results: Characteristic spatial variations in ACC and SCB histomorphometric parameters were present, none of which was significantly related to preconditioning exercise. Thickened, aberrantly mineralised ACC was found in 13/24 parasagittal grooves in the palmar slices and on the sagittal ridge of 4/12 dorsal slices of 18-month-old horses. Deep to thickened ACC, SCB had an open marrow structure, having not adopted the buttress morphology of the normal SCB plate. SCB in 3-year-old horses had incorporated early ACC defects as notches in parasagittal grooves and a hyaline cartilage island in a sagittal ridge. ACC was less stiff and SCB more stiff in affected than unaffected parasagittal grooves. Chondroclastic resorption in the parasagittal groove may be retarded as early as 3-6 months, possibly due to localised inhibition of ACC mineralisation. Linear defects in the Mc3 parasagittal groove may develop prior to entry to race training and are not significantly affected by preconditioning exercise. Early identification of affected individuals should aid in reducing condylar fracture risk.

Magister Scientiae Dentium - MSc(Dent) / This paper has attempted to describe the prenatal development of the mandible in humans and ita postnatal growth. The various theories of how this growth occurs have been described including the historical work by Brash, the' classical theory', .. which includes a section on the controversy regarding the term' growth centre' and its application to the mandibular condyle. Bjork's investigations using the implant method have been covered. This method allowed him to superimpose the mandibles in a longi tudinal growth study with more ease and accuracy than was formerly possible.Note that no mention is made in this paper of the error due to magni~cation changes in the radiographs resul~ing from the growth itself. Enlow's theory ,including his ideas on relocation,cortical drift,reversal etc. based on the morphology of the mandible are covered. The functional theory of Moss'which has many supporters and is perhaps one of the strongest theories is included with a further section on the role function plays The other main theory described is the theory of arcial growth is covered by Ricketts. The chin is a characteristic of Man and a short section will be found about its development Nowadays we are using prediction of the growth of an individual as an intgral part of our treatment plan in orthodontics .I have attempted to describe the structural features of acephalo metric radiograph which are our guidelines for prediction I have included at the end a short part about investigations using hormones to study their role in development.This only scratches the surface of the many hormonal studies carried out but serves to show another side of research concerning the development of the mandible.

INTRODUCTION: Orthopedic maxillary expansion, also commonly referred to as Rapid Maxillary Expansion (RME) is a widely used orthodontic technique for early treatment of skeletal transverse deficiencies1. Condylar changes in response to RME have been observed using a variety of imaging techniques such as tomograms2, magnetic resonance imaging3-4 and cone beam computerized tomography5. To this day, most of the studies have focused on changes in condylar position after RME but to best our knowledge, no study has examined the changes in condylar shape and volume in addition to position. OBJECTIVES: The aim of this retrospective cohort study is to determine the long term effect of Rapid Maxillary Expansion (RME) on condylar shape, volume and orientation as well as on mandibular rotation. METHOD: Pre- and post-expansion cone beam computerized tomography (CBCT) images of forty-four healthy subjects (mean age=11.8±2.06) who previously had undergone banded RME were selected from a CBCT repository. Due to extensive time range existing between the pre- and post-CBCTs (0.7-4.7y, average time = 2.4y ± 0.97), a stratified analysis was run to account for the subject’s growth. Two subgroups were created according to the Baccetti Cervical Maturation stage : a “growing” group (n=37, mean age=11.86y, diff CVM>1) and a “non-growing” group (n=7, mean age=11.73y, diff CVM<1). Linear, angular and volumetric changes as well as condylar surface area differences and changes in mandibular rotation were assessed on isolated 3D condyles using Mimics version 20.0 software (Materialise, Leuven, Belgium). The condyles were segmented by a plane passing through the sigmoid notch (Snp) and parallel to a Frankfort Horizontal derivative plane (FHD). Changes in mandibular rotation were evaluated by analyzing the alterations in the angle between mandibular plane and FHD plane before and after RME. Paired T test was performed to compare pre- and post- expansion for all variables stated above. Statistical significance was set at <0.05. RESULTS: In the “growing” group, the right and left condylar heights and widths significantly increased by 0.61mm±1.19mm (p=0.0035), 0.80±1.26 (p=0.0005) and 1.01mm±0.95mm (p<0.0001), 0.89±0.93 (p<0.0001) respectively. The right and left condylar volumes significantly increased by 117.7mm3±149.3mm3 (p<0.0001) and 106.7mm3±133.5mm3 (p<0.0001), respectively. In the “non growing” group, the right condylar height and the right condylar width statistically increased by 1.56mm±1.65 and 0.42mm±0.42 respectively. The right and left condylar volumes also increased by 114.1mm3±104.3 and 141.5mm3±89.1 respectively. No statistically significant changes were found in condylar orientation and mandibular plane angle for either of the two sub-groups. CONCLUSION: Right condylar height, width, and right and left volumes were significantly increased after rapid maxillary expansion. No statistically significant effect on condylar orientation and mandibular plane was found. Condylar growth still remains to be an important co-founding factor which potentially affected the results of our study. A control group will be required to assess the effects of growth in our current findings to limit the effects of growth on our results.

The mandibular condyles represent important growth sites within the facial skeleton. Condylar growth is not a pacemaker of mandibular development, but it provides regional adaptive growth that is of considerable clinical significance, as the condyle’s upward and backward growth movement regulates the anteriorly and inferiorly directed displacement of the mandible as a whole. Orthopedic problems of the temporomandibular joint (TMJ), such as displacement of the TMJ disk, are common in the adolescent population. Clinical studies of mandibular asymmetry and mandibular retrognathia in adults as well as in children and adolescents, have reported an association with coexisting non-reducing displacement of the TMJ disk without identifying the cause and effect. Through experimental studies causality has been established, and unilateral affliction during growth has been shown to retard ipsilateral mandibular development with facial asymmetry as the sequel. It was hypothesized that bilateral non-reducing TMJ disk displacement during growth would impair mandibular development bilaterally, resulting in mandibular retrognathia. TMJ disk displacement has repeatedly been demonstrated to induce histological reactions of the condylar cartilage. An additional assumption was therefore that a non-deranged TMJ disk function is crucial for the maintenance of the growing condyle’s biophysical environment, and that a connection ought to exist between the amount of condylar cartilage changes caused by TMJ disk displacement and the amount of subsequent adverse mandibular growth. It was also hypothesized that non-reducing displacement of the TMJ disk in growing individuals would result in qualitative and quantitative changes of the condylar subchondral bone. An improved experimental cephalometric method was developed in order to optimize the reliability of longitudinal radiographic evaluation of fast growing small animals. Bilateral non-reducing TMJ disk displacement was surgically created in ten growing New Zealand White rabbits, with ten additional rabbits serving as a sham operated control group. The amount and direction of craniofacial growth was followed over time in serial cephalograms, aided by tantalum implants in the jaws. The study period was chosen to correspond to childhood and adolescence in man. The assessed growth of each side of the mandible was correlated to the histological feature of ipsilateral condylar cartilage at the end of the growth period. The amount and composition of subchondral bone from three regions of interest in the condyle, and the expression of local growth factors in the adjacent condylar cartilage was evaluated. The results verified that bilateral non-reducing TMJ disk displacement retarded mandibular growth bilaterally; the extent corresponding to mandibular retrognathia in man. Displacement of the TMJ disk during the growth period induced condylar cartilage adaptive reactions that were associated with both an adverse amount and direction of mandibular growth, manifesting in a retrognathic mandibular growth pattern. Growth impairment fluctuated over time, with the most striking retardation occurring during periods of increased general growth, implying a local growth reduction explicitly counteracting general hormonal growth acceleration. A significant decrease of the total amount of subchondral bone, in spite of a general increase of new bone formation in the experimental condyles, pointed to a reparative compensation for an extensive resorption of subchondral bone due to displacement of the TMJ disk, but not to the extent that normal growth would be maintained. These results constitute an explanation for the adverse mandibular development following non-reducing TMJ disk displacement in growing individuals. This project has shown that non-reducing displacement of the TMJ disk during growth has significant consequences on facial development. The findings strongly advocate early and accurate diagnosis and treatment of TMJ disk displacement in the adolescent population, thereby presumably reducing the need for future orthodontic and surgical craniofacial corrective therapy. The results furthermore enhance the need for full appraisal of TMJ disk function in the adolescent population during orthodontic functional therapy, as the condylar cartilage and subchondral bone reactions to a concomitantly displaced non-reducing TMJ disk must be expected to interfere with the intended growth stimulating treatment. The findings of intact articular layers in spite of gross histological and morphological soft and hard tissue changes as a sequel to TMJ disk displacement in growing individuals, implicate a clinical risk of false positive radiographic diagnosis of degenerative changes of the TMJ in children and adolescents.

Os tratamentos da oclusão levaram à escolha da relação cêntrica (RC) como posição de referência devido à sua reprodutibilidade, o que favorece maior precisão do diagnóstico. As interferências oclusais e os conseqüentes deslocamentos condilares entre as posições mandibulares de RC e a máxima intercuspidação habitual (MIH) têm sido revelados como parte dos fatores etiológicos das disfunções temporomandibulares. Na tentativa de melhor esclarecer o papel dos deslocamentos condilares dentro do contexto da oclusão, morfológica e funcional, como fator de risco no desenvolvimento da DTM, este estudo transversal prospectivo propôs-se a avaliar os referidos deslocamentos. A amostra foi composta por 70 participantes, não desprogramados, divididos em grupo sintomático, segundo o critério RDC/TMD, e grupo assintomático. Para avaliação dos participantes, empregaram-se modelos de gesso montados em articulador Panadent. Foram obtidos registros de cera em MIH e RC, sendo este último obediente à técnica power centric (Roth). As diferenças entre as duas posições foram medidas nos três planos do espaço, em gráficos correspondentes aos lados direito, esquerdo e transversal, avaliadas quanto à magnitude e direção e comparadas quanto à sintomatologia e o gênero pela análise de variância. A possível correlação quanto à direção do deslocamento foi avaliada pelo teste qui-quadrado de homogeneidade. Para verificar a reprodutibilidade das medidas intra e interobservador foram calculadas correlações intraclasses e índice de Dahlberg. Os resultados mostraram repetibilidade e reprodutibilidade das medidas condilares. Nos indivíduos com DTM, os deslocamentos em valores médios absolutos no plano vertical foram de 1,48 mm do lado direito (IPC vert D) e de 1,72mm do lado esquerdo (IPC vert E). No plano horizontal foram de 0,63 mm do lado direito (IPC hor D) e de 0,64 mm do lado esquerdo (IPC hor E). No plano transversal (IPC trans) o valor médio do deslocamento foi de 0,41 mm. Os valores médios absolutos dos deslocamentos condilares em indivíduos assintomáticos foram de 1,22 mm no plano vertical do lado direito (IPC vert D) e 1,30 mm do lado esquerdo (IPC vert E). No plano horizontal do lado direito (IPC hor D), os valores médios foram de 0,63 mm e do lado esquerdo (IPC hor E) 0,63 mm. No plano transversal, o valor médio do deslocamento foi de 0,23 mm (IPC trans). Na comparação entre os grupos assintomático e sintomático, constatou-se que este último apresentou valores maiores quanto ao deslocamento vertical do lado esquerdo (E) (p=0,039) e no sentido transversal (p=0,015). Observou-se também nesse grupo maior prevalência de deslocamento no sentido distal quando comparado ao grupo assintomático. Na associação entre a sintomatologia e a direção de deslocamento, verificou-se que o deslocamento condilar horizontal direito apresentou associação estatística com a sintomatologia (p=0,015). Não foram encontradas diferenças relativas à sintomatologia quanto ao gênero. O primeiro ponto de contato em RC mostrou-se localizado em sua grande maioria no segundo molar permanente, tanto no grupo sintomático (94,2%) quanto no assintomático (91,4%). / Centric relation (CR) is considered a reference position in the treatment of occlusion due to its reproducibility, thus favoring accuracy of diagnosis. Occlusal interference and consequent condylar displacement between CR and CO (centric occlusionmaxim intercuspation) have been revealed as part of the etiologic factors of temporomandibular dysfunction. In an attempt to better understand the role of condylar displacement in the context of morphologic and functional occlusion as a risk factor in TMD development, this transverse prospective study intends to evaluate the referred displacement. The sample was composed of 70 participants, not deprogrammed, divided into a symptomatic group, according to RDC/TMD criteria, and another, asymptomatic. From each subject, a wax registration in CO and CR was taken, the latter obeying the power centric technique (Roth). Cast models were mounted on a Panadent. articulator. Condylar displacement between CO and CR on three-spatial planes was measured on graphs corresponding to right, left and transverse sides, and appraised for magnitude and direction, determined by condilar position indicator instrumentation (Panadent-CPI). Analysis of variance test was used for symptom and gender comparison. The possible correlation for displacement direction and TMD was evaluated by the qui-square test of homogeneity. Inter and intraoperator reproducibility measurement error and reliability were calculated by intra-class correlations and the Dahlberg index. Low error showed high reliability and reproducibility. In TMD individuals, absolute mean values of condylar displacements in the vertical plane were 1, 48 mm on the right side (CPI vert R) and 1,72mm on the left side (CPI vert L). In the horizontal plane were 0,63mm on the right side (CPI hor R), and 0,64mm on the left (CPI hor L). In the traverse plane (IPC trans), mean value of displacement was 0,41mm. The absolute mean value of condylar displacement in asymptomatic individuals was 1,22 mm in the vertical plane on the right side (CPI vert R), and 1,30mm on the left side (CPI vert L). In the horizontal plane on the right side (CPI hor R) were 0,63mm and on the left side (CPI hor L), 0,63mm. In the tranverse plane (CPI trans) the mean value was of 0,23mm. Comparing asymptomatic and symptomatic groups it was verified that the latter presented larger values in vertical displacement on the left side (p=0,039) and in the transverse plane (p=0,015). In this group, larger displacement prevalence was also observed in distal direction when compared to the asymptomatic group. In the association between symptoms and displacement direction, it was verified that horizontal condilar displacement of the right side presented statistical association (p = 0,015). It was noted that, three-dimensional condylar displacement was found in both symptomatic and asymptomatic individuals. No correlation was found between patient gender and the presence of TMD symptoms. The initial premature contact in CR was detected, in most of the cases, on the second permanent molar, in both symptomatic (94,2%) and asymptomatic (91,4%) group.

A síndrome aurículo-condilar (ACS) apresenta um modelo de herança autossômica dominante e é principalmente caracterizada por malformações auriculares, articulação temporomandibular anormal e hipoplasia do côndilo e da mandíbula. Devido às estruturas acometidas, é considerada uma patologia de primeiro e segundo arcos faríngeos. Com somente alguns casos clínicos descritos na literatura, o gene causador da ACS não é conhecido. Estudos recentes de nosso grupo mapearam o primeiro lócus associado à síndrome, 1p21.1-q23.3 (família ACS1), enquanto que na segunda família estudada por nós (ACS2), não houve evidência de ligação com os marcadores desta região, sugerindo heterogeneidade genética a esta doença. Nossos principais objetivos no presente trabalho foram: identificar o gene responsável por ACS1 e mapear o lócus associado à ACS2. Para o estudo de ACS1, dada a grande extensão da região candidata, com aproximadamente 1004 genes, utilizamos uma abordagem alternativa: análise de transcriptoma durante a diferenciação condrogênica a partir de células-tronco mesenquimais para seleção e subseqüente seqüenciamento de genes candidatos. Através do estudo de expressão gênica entre controle e paciente ACS1, selecionamos e realizamos o seqüenciamento de dois genes. Não detectamos nenhuma alteração patogênica nestes genes e, portanto, é pouco provável que um destes seja responsável pela ACS1. Já na família com ACS2, através de estudo de ligação com uso de microarrays de SNP e marcadores microssatélites, mapeamos o segundo lócus associado à ACS. Estudos complementares estão sendo realizados para a identificação dos alelos causadores de ACS1 e ACS2. Estes resultados, além de sua importância para o aconselhamento genético, poderão contribuir para a compreensão do desenvolvimento embrionário das estruturas acometidas nessa síndrome. / The auriculo-condylar syndrome is an autosomal dominant disease characterized by malformed ears, abnormal temporomandibular joint and condyle and mandible hypoplasia. It is considered a syndrome of the first and second pharyngeal arches. With only a few clinical cases reported in the literature, the gene that causes ACS is not known. Recent studies from our group mapped the first locus associated to the syndrome, 1p21.1-q23.3 (ACS1 family), while in the second family studied by us (ACS2), there was no evidence of linkage with this region, suggesting genetic heterogeneity of this disease. Our main objective in this study was to identify the gene responsible for ACS1 and map the locus associated to ACS2. In the study of ACS1, given the large extent of the candidate region, with approximately 1004 genes, we used an alternative approach: transcriptome analysis during chondrogenic differentiation of stem cells of a patient and a control for screening and subsequent sequencing of candidate genes. The two genes selected through this strategy were sequenced in ACS1 patients, however, not pathogenic mutation was identified. Therefore, it is very unlikely that mutations in these genes are causative of ACS1. In the family with ACS2, through linkage study using SNP microarray and microsatellite markers, we mapped the second locus associated to ACS. Additional studies are being conducted in order to identify the alleles causing ACS1 and ACS2. These results will not only contribute to a better genetic counseling for families with ACS but they will also contribute to the understanding of the embryonic development of the structures affected in this syndrome.

Neste trabalho, estudamos duas malformações craniofaciais mendelianas, decorrentes de um distúrbio do desenvolvimento dos primeiro e segundo arcos faríngeos: a síndrome de Treacher Collins (STC) e a síndrome Aurículo-condilar (SAC). A identificação de genes e de mecanismos moleculares associados a essas condições, além de contribuir para a compreensão do desenvolvimento das estruturas derivadas desses arcos faríngeos, é fundamental para o desenvolvimento do diagnóstico molecular, uma ferramenta importante para diagnóstico diferencial e aconselhamento genético. Contribuímos para uma melhor caracterização clínica da SAC com a descrição de uma nova família com 11 afetados. Após excluirmos quatro genes/regiões candidatas para síndromes de 1º e 2º arcos faríngeos, realizamos estudos de ligação usando marcadores polimórficos ao longo do genoma. Mapeamos o primeiro lócus associado à SAC, 1p21.1-q23.3 (lod score=3.0), e nossos dados sugerem que há heterogeneidade genética para essa patologia. Com relação ao estudo da STC, realizamos uma extensa revisão da nomenclatura das mutações patogênicas descritas na literatura, além de investigar mecanismos mutacionais atípicos na STC, corroborando a hipótese de que mutações nos exons que sofrem splicing alternativo são capazes de gerar o fenótipo da síndrome. Demos continuidade à caracterização do espectro de mutações no gene TCOF1 e investigamos a correlação genótipo-fenótipo numa amostra de 58 pacientes com STC. A análise dos dados de polimorfismos da região codificadora do gene permitiu que fizéssemos inferências sobre o regime de seleção ao qual o TCOF1 está submetido, e os resultados sugeriram que o gene TCOF1 está sob seleção purificadora, que atua sobre mutações fracamente deletérias. Também inferimos a fase para um conjunto de polimorfismos da região codificadora, verificando se havia associação de algum haplótipo à gravidade do quadro clínico ou à predisposição para a doença. Dada a observação de ausência de correlação haplótipo/genótipo-fenótipo, testamos a hipótese de que variações nos níveis de expressão do alelo normal poderiam ser responsáveis pela variabilidade clínica observada nos pacientes portadores da STC. Para tanto, iniciamos o estudo funcional das regiões regulatórias do gene TCOF1 , inclusive, de regiões distantes do promotor mínimo, preditas como enhancers. Identificamos polimorfismos em sua região promotora, sendo um deles capaz de diminuir os níveis de transcrição e de afetar a ligação do fator de transcrição YY1 ao promotor do TCOF1 . Caracterizamos a ação de YY1 como repressora in vitro. Testamos também a hipótese de haploinsuficiência como mecanismo associado à STC. Quantificamos os níveis de transcritos do TCOF1 em indivíduos afetados e normais e observamos uma diferença significativa. Nosso trabalho corrobora a hipótese de haploinsuficiência e mostra pela primeira vez que pacientes têm degradação de transcritos. Também investigamos a possibilidade de os níveis de transcritos estarem correlacionados à variabilidade fenotípica. Comparamos os dados de expressão de cada paciente à freqüência de nove sinais clínicos principais da STC, mas nenhuma correlação foi observada. Investigamos o padrão de metilação da ilha CpG do gene TCOF1 em pacientes e em controles, com o intuito de verificar se diferentes níveis de metilação inter-individual estariam associados à grande variação na expressão gênica. Demonstramos que a metilação da ilha CpG não é o mecanismo regulatório por trás dessa ampla variação de expressão do TCOF1 / In the present study, we investigate two craniofacial mendelian disorders, resulting from abnormalities in the development of the first and second pharyngeal arches: the Treacher Collins Syndrome (TCS ) and the auriculo condylar syndrome (ACS). The identification of genes and molecular mechanisms associated to these conditions, in addition to contributing to the understanding of the development of structures derived from these pharyngeal arches, is fundamental for the development of molecular diagnostics, an important tool for differential diagnosis and genetic counseling. We contributed to a better clinical characterization of ACS with a description of a new family with 11 affected individuals. After excluding four candidate genes/regions for syndromes of the 1st and 2nd pharyngeal arches, we carried out linkage studies using polymorphic markers throughout the genome. We mapped the first locus associated to ACS, 1p21.1-q23.3 (lod score=3.0), and our data suggest genetic heterogeneity exists for this pathology. With respect to the study of TCS , we carried out an extensive review of the nomenclature for the pathogenic mutations described in the literature, in addition to investigating atypical mutation mechanisms in TCS , corroborating the hypothesis that mutations in the exons that undergo alternative splicing can result in the TCS phenotype. We continued the characterization of the mutation spectrum for TCOF1 and we investigated the genotype-phenotype correlation in a sample of 58 patients with TCS . The analysis of polymorphisms in the coding region allowed us to make inferences about the selective regime experienced by TCOF1 , and our results suggested that TCOF1 is under purifying selection, which acts upon weakly deleterious mutations. We also inferred the phase for a set of polymorphisms in the coding region, testing whether there was association between any haplotype and the severity of the phenotype or the susceptibility to the disease. Given the observation of no correlation between haplotype/genotype and phenotype, we tested the hypothesis that variation in the levels of expression of the normal allele could be responsible for the clinical variability observed in TCS patients. To do this, we started a functional study of the TCOF1 regulatory regions, including regions distant from the minimal promoter, predicted to be enhancers. We identified polymorphisms in the promoter region, one of which reduced the levels of transcription and affected the binding of the YY1 transcription factor to the TCOF1 promoter. Using an in vitro assay we characterized YY1 as a repressor. We also tested the hypothesis of haploinsufficiency as a mechanism associated to TCS . We quantified the levels of TCOF1 transcripts in normal and affected individuals and found a significant difference. Our study corroborates the haploinsufficiency hypothesis and for the first time shows that patients have transcript degradation. We also investigated the possibility that transcripts levels are correlated to phenotypic variability. We compared the expression data for each patient with the frequency of nine clinical signs of TCS , but no correlation was found. We investigated the pattern of methylation on the CpG island of TCOF1 in patients and controls, in order to test whether different levels of methylation among individuals were associated to the great variation in gene expression. We demonstrated that methylation of the CpG island is not the regulatory mechanisms underlying the broad variation in TCOF1 expression.

A articulação temporomandibular (ATM) representa a ligação da mandíbula com o crânio, ela é uma das articulações mais complexas do corpo humano, devido aos complicados mecanismos envolvidos em seu funcionamento, podendo levar a alta incidência de disfunção temporomandibular (DTM). As DTMs envolvem o sistema mastigatório, afetando músculos, articulações e estruturas relacionadas. São classificadas em DTM muscular, DTM articular e DTM mista (muscular e articular). Subdividindo a DTM articular encontramos a hipermomibilidade condilar ou subluxação, caracterizada pelo deslocamento da cabeça da mandíbula além da eminência articular durante a abertura bucal, condição que predispõe a ATM à sobrecarga mecânica e instabilidade de suas estruturas. Portanto, o objetivo deste estudo foi analisar a relação entre hipermobilidade condilar e abertura bucal máxima, através de radiografias transcranianas. Foram traçadas 57 radiografias transcranianas da ATM, totalizando 114 traçados de articulações temporomandibulares. Sobre o traçado foram confeccionadas retas verticais e paralelas que passaram pelo ponto mais convexo da cabeça da mandíbula na posição de boca aberta e pelo ponto mais convexo da eminência articular. A distância entre as duas retas foi obtida através de paquímetro digital, assim como a medida da abertura bucal máxima durante a tomada radiográfica. Os dados foram analisados estatisticamente através de análise descritiva, teste de correlação e regressão. Foi encontrada uma moderada correlação entre abertura bucal máxima e deslocamento condilar, a média entre as medidas de máxima abertura bucal foi 42,5mm e de deslocamento condilar 5,3mm. Concluindo, o aumento na medida de abertura bucal promove o aumento no deslocamento da cabeça da mandíbula para além do ápice da eminência articular durante o movimento de máxima abertura bucal. / The temporomandibular joint (TMJ) is the link between the mandible and skull. The TMJ is considered one of the most complex joint in the human body due to the complex mechanisms involved in its joint function, which may cause the high incidence of temporomandibular disorder (TMD). The TMDs involves the masticatory system, affecting muscles, joints and related structures. The TMDs are classified in muscular TMD, joint TMD and mixed TMD (muscle and joint). In the subdivision of the joint TMD, we can find the condylar hypermobility or subluxation, which is characterized by head of the mandible displacement jointly with the articular eminence during mouth opening, predisposing the TMJ to mechanical overload and structural instability. Furthermore, the aim of this study was to analyze the relation between condylar hypermobility and maximum mouth opening, using transcranial radiographs. Fifty-seven transcranial radiographs of TMJ and one hundred and fourteen temporomandibular joint were traced. Vertical and parallel straight were made through the most convex point of head of the mandible with maximum mouth opening and the most convex point of articular eminence. The distance between straights and the maximum mouth opening during radiographic were measured by digital caliper. The data were analyzed through descriptive analysis, correlation test and regression test. The results indicated a moderate correlation between maximum mouth opening and condylar displacement. The mean value of maximum mouth opening was 42,5mm, and the mean value of condylar displacement was 5,3mm. In conclusion, the increase in the measurement of mouth opening caused increase in displacement of the head of mandible, which is beyond of the articular eminence apex during maximum movement of mouth opening.

Deslocamentos das cabeças da mandíbula entre as posições de máxima intercuspidação habitual (MIH) e de relação cêntrica (RC) são ocorrências encontradas nas mordidas cruzadas posteriores unilaterais em crianças. Desta forma os mesmos foram estudados em 18 crianças com a referida maloclusão, com media de idade de 7,2 anos para o gênero feminino e 8,4 anos para o gênero masculino. A correção dessa foi efetuada com o aparelho de recobrimento oclusal de acrílico associado ao parafuso hyrax, ajustado à oclusão do paciente de modo a promover contatos bilaterais simultâneos e múltiplos, resultando em algum grau de desprogramação. Os deslocamentos foram medidos nos três planos do espaço por meio do indicador de posição condilar (IPC), antes e após a expansão rápida da maxila com o referido aparelho. Pode-se observar que os deslocamentos condilares entre as posições de RC e MIH, nos planos vertical e horizontal, no tempo pré-expansão, mostraram-se significativamente maiores que os encontrados no tempo pós-expansão, demonstrando assim, diminuição dos mesmos após a correção da maloclusão. No plano transversal não houve diferenças entre os tempos pré e pós-expansão. A comparação entre os lados direito e esquerdo dos deslocamentos estudados no tempo pré-expansão, evidenciou diferenças estatísticamente significantes apenas no plano horizontal (p= 0,039), sendo maiores os deslocamentos do lado esquerdo. No tempo pós-expansão, não se encontraram diferenças estatisticamente significantes entre os lados direito e esquerdo, indicando maior semelhança entre os lados, após a correção das mordidas cruzadas posteriores unilaterais. Os deslocamentos no plano horizontal, de sentido mesial, apresentaram-se em maior porcentagem no lado esquerdo no tempo pré-expansão e no lado direito, no tempo pós-expansão. Os deslocamentos no plano transversal apresentaram maior porcentagem para o lado esquerdo, tanto no tempo pré-expansão, quando a mordida cruzada era deste mesmo lado, como no tempo pós-expansão, quando a mordida cruzada original era do lado oposto. Entretanto, tais prevalências citadas não resultaram em diferenças estatisticamente significantes em nenhum dos sentidos considerados, tanto nos planos horizontal como transversal. As mordidas cruzadas do lado direito foram prevalentes tanto para o gênero feminino como masculino. Após a ERM as cabeças da mandíbula assumiram uma posição mais concêntrica, o que pode favorecer o equilíbrio e desenvolvimento adequados de todo o sistema envolvido. / Changes in the relationship between the condyle and glenoid fossa when the habitual intercuspal position (MHI), to the position of centric relation (CR) events are found in unilateral posterior cross bites in children before treatment of malocclusion installed. Thus condylar displacement between the positions mentioned were studied in 18 children with this malocclusion with a mean of 7.2 years for females and 8.4 years for males. The correction of this device was made with the acrylic coating associated with occlusal screw hyrax, the same being adjusted to the patient\'s occlusion promoting bilateral simultaneous and multiple contacts, resulting in some degree of deprogramming. The displacements were measured in three planes of space through the condylar position indicator before and after rapid maxillary expansion with that instrument. It can be observed that the condylar displacement between the positions of RC and MIH, vertical and horizontal, in the pre-expansion, were significantly higher than those found in the post-expansion, thus demonstrating a decrease of it after correction of malocclusion. In the transverse plane there were no differences between pre-and post-expansion. The comparison between right and left shifts studied in the pre-expansion, showed statistically significant differences only in the horizontal plane (p = 0.039), the greatest displacements side esquerdo.No time post-expansion, there were no statistical differences significant between the left and right sides, indicating a greater similarity between the sides, after correction of cross bites. The displacements in the horizontal plane, the mesial, presented themselves in higher percentage on the left side in the pre-expansion and the right side, in the post-expansion. The displacements in the transverse plane showed a higher percentage to the left side, both in the pre-expansion, when cross-bite was of the same side as in the post-expansion, when the original cross-bite was on the opposite side. Prevalences were not identified statistically significant shifts in the way of mesial and distal in the horizontal plane, or left and right in the transverse plane, both in pre and post-expansion, regardless of which side of the crossbite. The cross bite on the right were so prevalent for females as males. After the ERM heads jaw took on a more concentric position, favoring a balanced and proper development of the entire system involved.

A articulação temporomandibular (ATM) representa a ligação da mandíbula com o crânio, ela é uma das articulações mais complexas do corpo humano, devido aos complicados mecanismos envolvidos em seu funcionamento, podendo levar a alta incidência de disfunção temporomandibular (DTM). As DTMs envolvem o sistema mastigatório, afetando músculos, articulações e estruturas relacionadas. São classificadas em DTM muscular, DTM articular e DTM mista (muscular e articular). Subdividindo a DTM articular encontramos a hipermomibilidade condilar ou subluxação, caracterizada pelo deslocamento da cabeça da mandíbula além da eminência articular durante a abertura bucal, condição que predispõe a ATM à sobrecarga mecânica e instabilidade de suas estruturas. Portanto, o objetivo deste estudo foi analisar a relação entre hipermobilidade condilar e abertura bucal máxima, através de radiografias transcranianas. Foram traçadas 57 radiografias transcranianas da ATM, totalizando 114 traçados de articulações temporomandibulares. Sobre o traçado foram confeccionadas retas verticais e paralelas que passaram pelo ponto mais convexo da cabeça da mandíbula na posição de boca aberta e pelo ponto mais convexo da eminência articular. A distância entre as duas retas foi obtida através de paquímetro digital, assim como a medida da abertura bucal máxima durante a tomada radiográfica. Os dados foram analisados estatisticamente através de análise descritiva, teste de correlação e regressão. Foi encontrada uma moderada correlação entre abertura bucal máxima e deslocamento condilar, a média entre as medidas de máxima abertura bucal foi 42,5mm e de deslocamento condilar 5,3mm. Concluindo, o aumento na medida de abertura bucal promove o aumento no deslocamento da cabeça da mandíbula para além do ápice da eminência articular durante o movimento de máxima abertura bucal. / The temporomandibular joint (TMJ) is the link between the mandible and skull. The TMJ is considered one of the most complex joint in the human body due to the complex mechanisms involved in its joint function, which may cause the high incidence of temporomandibular disorder (TMD). The TMDs involves the masticatory system, affecting muscles, joints and related structures. The TMDs are classified in muscular TMD, joint TMD and mixed TMD (muscle and joint). In the subdivision of the joint TMD, we can find the condylar hypermobility or subluxation, which is characterized by head of the mandible displacement jointly with the articular eminence during mouth opening, predisposing the TMJ to mechanical overload and structural instability. Furthermore, the aim of this study was to analyze the relation between condylar hypermobility and maximum mouth opening, using transcranial radiographs. Fifty-seven transcranial radiographs of TMJ and one hundred and fourteen temporomandibular joint were traced. Vertical and parallel straight were made through the most convex point of head of the mandible with maximum mouth opening and the most convex point of articular eminence. The distance between straights and the maximum mouth opening during radiographic were measured by digital caliper. The data were analyzed through descriptive analysis, correlation test and regression test. The results indicated a moderate correlation between maximum mouth opening and condylar displacement. The mean value of maximum mouth opening was 42,5mm, and the mean value of condylar displacement was 5,3mm. In conclusion, the increase in the measurement of mouth opening caused increase in displacement of the head of mandible, which is beyond of the articular eminence apex during maximum movement of mouth opening.