CBCT location of the fusion between the buccal and lingual cortical in the mandibular ramus: importance to sagittal split osteotomy.

BACKGROUND: Mandibular Sagittal Split Osteotomy (MSSO) is a popular technique in orthognathic surgery used both to advance and to retreat the mandible. However, MSSO may incur in important complications, such as bad splits and sensorineural injuries. Knowing the location of the fusion between the buccal and lingual cortical (FBLC) in the mandibular ramus and the bone thickness in the region where osteotomies will be performed is determinant in MSSO planning to avoid complications. The aim of this study was to document and evaluate possible differences between sexes regarding the location of the FBLC in relation to the superior cortical of mandibular foramen (MF) and bone thickness in the region of interest for MSSO in a Brazilian population. MATERIAL AND METHODS: Eighty five cone-beam Computed Tomography (CBCT) scans were used to perform linear measurements to determine the location of the FBLC. Bone thickness from the mandibular canal (MC) to the cortical external surfaces and the diameter of the MC were measured at three different points: mandibular ramus (A), mandibular angle (B) and mesial of the second molar (C). RESULTS: The FBLC was located at a mean distance of 8.3 mm from the superior cortical of the MF in males and 8.1 mm in females. There was no difference between males and females regarding the mean bone thickness from the MC to the buccal external surface at all the points investigated (p>0.05). Bone thickness from the lingual external surface to the MC was bigger among females than males in regions B and C (p < 0.05). The diameter of the MC was bigger among males in regions B and C. CONCLUSION: Sexual dimorphism regarding mandibular bone thickness but not regarding the location of FBLC was present. This fundamental knowledge may assist to the panning of MSSO.

How to assess tonsilloliths and styloid chain ossifications on cone beam computed tomography images.

OBJECTIVE: The aim of this study was to establish an anatomical guideline in cone beam computed tomography (CBCT) images to discriminate soft-tissue calcifications, specifically, tonsilloliths, and styloid chain ossification (SCO) in the multiplanar reconstruction screen of the i-CAT Vision. MATERIALS AND METHODS: We analyzed 100 pairs of CBCT images and panoramic digital radiographies regarding the presence or absence of tonsilloliths and SCO. The intraobserver agreement varied from excellent to good. The statistical analyses included Mann-Whitney test, chi-square test, Spearman test, Student's t-test, and Wilcoxon test. The analyses were repeated without the guideline to verify its effectiveness. RESULTS: A total of 25 tonsilloliths were found in panoramic images while CBCT images revealed 60. Panoramic and CBCT images showed 42% and 63% of patients positive to SCO, respectively. We found a statistically significant difference when comparing the presence of tonsilloliths and SCO between panoramic and CBCT images (Wilcoxon test P < 0.05). The analyses without the guideline showed that the observer tended to diagnoses more false-positive SCO. CONCLUSION: Based on the results, we can suggest that CBCT images are more suitable to differentiate tonsilloliths and SCO than panoramic images. The guideline was more important to diagnosis SCO than tonsilloliths. SCO was misclassified in 34% without the guideline.