CBCT study on the prevalence, morphology and position of the mandibular incisive canal in a North-Brazilian population.

Background: The mandibular incisive canal (MIC) is an anatomic structure to be considered in treatment planning for surgeries in the anterior region of the mandible. Awareness of the MIC increased with the use of 3D imaging for treatment planning, such as cone beam computed tomography (CBCT). This study aimed to use CBCT to assess the prevalence, morphology and position of the MIC among North-Brazilians. Material and Methods: The sample consisted of CBCT scans of 100 hemi-mandibles (50 individuals) that were assessed for the absolute (n) and relative frequency of the MIC. The morphological component of this study was the diameter (mm) of the detected MIC in five anatomic sites between the mental foramen and the midline. Within the interformainal region, the position of the MIC was assessed by measuring (mm) the distances between the MIC and the basal, vestibular and lingual cortical bone surfaces. Results: The prevalence of the MIC was >76% considering the different anatomic regions screened in CBCT. The mean diameter of the MIC progressively reduced from 1.29 mm to 0.86 throughout the five anatomic regions measured. The position of the MIC showed a downward trajectory away from the lingual cortical bone surface. Conclusions: MIC was a highly prevalent anatomic structure in the studied sample. The funnel-shaped outline of the MIC and its trajectory into the interforaminal region highlighted a major risk of damage to the neurovascular bundle in surgeries (e.g. implant placement) that are close to the mental foramen and the vestibular cortical bone. Key words:Anatomy, cone beam computed tomography, imaging, mandibular incisive canal, oral radiology.

Is mouth-breathing related to alterations in facial soft tissues?

Objective: To compare the facial soft tissues of nasal breathers (NB) and mouthbreathers (MB) using cone-beam computed tomography (CBCT).Methods: This was a comparative study of four angular and eight linearcephalometric variables obtained from the facial soft tissues of 43 young menand women aged between 11 and 24 years. Subjects had tomographic examinationprior to the orthodontic treatment and were previously divided into two groupsby an otolaryngologist according to the respiratory pattern of nasal or mouthbreathing. The selection was made in accordance with the results of: clinicalexamination, rhinoscopy, and nasal endoscopy. The data obtained from thesoftware InVivo Dental 5.3 (Anatomage - San Jose, California) was evaluated bycomparing values measured between MB and NB groups. Results: There weresignificant differences between groups for variables, "nasolabial angle", inclinationof upper central incisor" and "convexity of the facial soft tissues". Conclusion:Adolescent and young adult mouth breathers present an open nasolabial angledue to the retroinclination of their upper incisors. In addition to greater convexityof the facial soft tissues.

Objetivo: Comparar os tecidos moles faciais de respiradores nasais (RN) e bucais(RB), utilizando imagens de tomografia computadorizada de feixe cônico (TCFC).Métodos: Foi realizado um estudo comparativo composto por quatro variáveiscefalométricas angulares e oito lineares, obtidas de tecidos moles faciais deindivíduos RN e RB, em uma amostra composta por 43 indivíduos jovens deambos os sexos, com idades entre 11 e 24 anos, submetidos ao exame tomográficoanteriormente ao tratamento ortodôntico. Os indivíduos foram previamentedivididos em dois grupos por um otorrinolaringologista, de acordo com o padrãorespiratório. O diagnóstico da respiração bucal foi feito em conformidade comos resultados de exames específicos: exame clínico, rinoscopia e endoscopia nasal.Os dados obtidos a partir do software InVivo 5.3 Dental (Anatomage - San Jose,Califórnia) foram avaliados através da comparação dos valores das mediçõesdas variáveis dos grupos RN e RB, além da comparação das diferenças entreesses valores. Resultados: Houve diferenças estatisticamente significativas entreos grupos com relação às variáveis, "ângulo nasolabial", "inclinação do incisivocentral superior" e "convexidade dos tegumentos faciais". Conclusão: Osrespiradores bucais adolescentes e adultos jovens apresentam ângulo nasolabialmais aberto, devido à maior inclinação lingual do longo eixo dos incisivossuperiores, além de maior convexidade dos tecidos moles faciais.

Agreement in the determination of preformed wire shape templates on plaster models and customized digital arch form diagrams on digital models.

INTRODUCTION: The aim of this study was to verify the accuracy of preformed wire shape templates on plaster models and those of customized digital arch form diagrams on digital models. METHODS: Twenty pairs of dental plaster models were randomly selected from the archives of the Department of Orthodontics of Federal Fluminense University, Niterói, Rio de Janeiro, Brazil. All plaster model samples were scanned in a plaster model scanner to create the respective digital models. Three examiners defined the arch form on the mandibular arch of these models by selecting the ideal preformed wire shape template on each plaster model or by making a customized digital arch form on the digital models using a digital arch form customization tool. These 2 arch forms were superimposed by the best-fit method. The greatest differences in the 6 regions on the superimposed arches were evaluated. Each examiner presented a descriptive analysis with the means, standard deviation, and minimum and maximum intervals of the differences on the superimpositions. Intraclass correlation coefficient and paired t tests were used to evaluate the accuracy of the superimpositions. RESULTS: Among the 6 regions analyzed in the superimpositions, the largest differences in the anterior and premolar regions were considered clinically insignificant, whereas the largest differences in the right molar region, especially the second molar area, were considered clinically significant by all 3 examiners. The intraclass correlation coefficients showed a weak correlation in the premolar region and moderate correlations in the anterior and molar regions. The paired t test showed statistically significant differences in the left anterior and premolar regions. CONCLUSIONS: The superimpositions between the arch forms on plaster and digital models were considered accurate, and the differences were not clinically significant, with the exception of the second molar area. Despite the favorable results, the requirement of correcting some software problems may hamper the transition from plaster to digital models.