Quantification of volumetric, surface area and linear airway changes after orthognathic surgery: a preliminary study

The aim of this study was to conduct a retrospective evaluation of the volumetric, cross-sectional surface area and the linear airway changes in healthy subjects undergoing orthognathic surgery. Materials and methods A total of 10 patients were included in this study and categorized into two groups. The first group consisted of five patients who underwent maxillary and mandibular advancements (MMA) with genioplasty. The remaining five patients who underwent maxillary advancement with mandibular setback (MAMS) comprised the second group. The changes in airway volume, surface area, and linear values obtained from defined hard and soft tissue parameters were evaluated using preoperative and postoperative cone-beam computed tomography. A paired t-test was used to explore the statistical significance. Results A statistically significant increase in the airway volume (34.3%) was observed in the MMA group. The changes in the MAMS group were not statistically significant, although an average volumetric decrease of 8.8% was observed. The minimal axial surface area measurements in the MMA group at the levels of the soft palate and the tongue were significantly increased (56.8% and 44.9%, respectively). However, MAMS resulted in no significant changes at these levels (11.2% and 9.1% decrease, respectively). Linear changes showed a statistically significant increase in the airway in the MMA group, whereas the same measurements failed to produce significant changes in the MAMS group. Conclusion As there were no significant changes in the measured parameters, surgeons can have greater confidence that MAMS does not have any negative influence on the airway

Comparative assessment of 3D reconstruction technique and Cavalieri’s principle in predicting the mandibular bone defect volumes

Purpose The objective of this study was to compare the accuracy of the Cavalieri’s principle and 3D reconstruction in predicting the volume of a bony defect. Materials and Methods Defects of the same approximate size were created on nine artificial mandibles. The actual volume of the defect on each mandible was measured by water displacement, and served as the control. Each mandible was then scanned using a CBCT and volume measurements were made for each defect using two techniques: Cavalieri’s principle and 3D reconstruction. For each defect, the volume obtained by each of the two techniques was compared to the control volume using the analysis of variances (ANOVA) with p<0.05. Results ANOVA between the control, 3D reconstruction and Cavalieri’s principle groups showed no statistically significant differences (p=.058). When the control group was further analyzed by Dunnett’s post-hoc test, the results from Cavalieri’s principle were found to be statistically different than the control group (p=.035), whereas the results of 3D reconstruction technique did not reach the level of significance (p=.523). Conclusion Cavalieri’s principle significantly underestimates the actual control volume, and is less accurate than the 3D reconstruction technique. The 3D reconstruction method is a reliable technique in measuring volume of bony defects

Hounsfield unit comparison of grafted versus non-grafted extraction sockets

Volumetric changes of the alveolar ridge after socket preservation with various techniques have been investigated frequently. However, changes in bone density and quality of bone within the extraction sockets have seldom been studied. The purpose of this study was to evaluate the bone quality of grafted versus non-grafted socket sites prior to dental implant placement using Hounsfield unit (HU) values derived from cone-beam computed tomography (CBCT) imaging. The data was collected from 39 healed extraction sites reviewed over a one-year period. Subjects eligible for the study had a bone replacement graft and barrier membrane. Both study and control groups had CBCT scans performed immediately after extraction and four to five months after extraction for planning implant placement. HU values were measured from the CBCT scans and compared between groups. Intragroup variability was assessed utilizing standard deviation and standard error of the mean. Intergroup differences were evaluated using unpaired 1-test. A generalized lack of significant difference in bone quality was observed between groups with the only statistically significant difference observed in the posterior maxilla. Future radiographic and histologic assessments of bone quality after socket preservation are required to determine the `ideal' approach to preserve an extraction socket prior to implant placement