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Objective: The objectives of this study were (1) to develop a 3D cephalometric analysis scheme applicable to assessing dentofacial deformities; and (2) to create a normative database of 3D cephalometric measurements for adult Chinese in Hong Kong., Study Design: A cross-sectional study was conducted on 50 male and 50 female adults with normal balanced facial profile and occlusion. Cone-beam computed tomography and stereo photogrammetry imaging were performed on all subjects. Three-dimensional virtual models were generated from imaging data, and cephalometric analysis was performed using specialized software. A new 3D cephalometric analysis scheme appropriate for orthognathic surgery as well as a new reference plane (supraorbital margin plane) for midfacial assessment was used in this study., Results: The cephalometric norms generated in this study were comparable with those reported in the literature for conventional 2D cephalometric analysis and the unique features of Chinese faces. The results also showed significant differences between males and females in most of the facial height measurements (P < .01)., Conclusions: This is the first database of 3D cephalometric norms based on CBCT and 3D photogrammetry of the Chinese population in Hong Kong. This can be a useful reference for characterizing facial deformities in 3 dimensions. Moreover, 3D cephalometric analysis has the potential of incorporating new measurement methods that are difficult if not impossible in 2D cephalometric analysis., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Objective: The purpose of this research was to provide further evidence to demonstrate the precision and accuracy of maxillofacial linear and angular measurements obtained by cone-beam computed tomography (CBCT) images., Study Design: The study population consisted of 15 dry human skulls that were submitted to CBCT, and 3-dimensional (3D) images were generated. Linear and angular measurements based on conventional craniometric anatomical landmarks, and were identified in 3D-CBCT images by 2 radiologists twice each independently. Subsequently, physical measurements were made by a third examiner using a digital caliper and a digital goniometer., Results: The results demonstrated no statistically significant difference between inter- and intra-examiner analysis. Regarding accuracy test, no statistically significant differences were found of the comparison between the physical and CBCT-based linear and angular measurements for both examiners (P = .968 and .915, P = .844 and .700, respectively)., Conclusions: 3D-CBCT images can be used to obtain dimensionally accurate linear and angular measurements from bony maxillofacial structures and landmarks.

Objective: The purpose of the present study was to assess the accessory mental foramen using cone-beam computed tomography (CBCT) images., Study Design: A total of 157 patients were enrolled in this investigation. The mental and accessory mental foramina, which show continuity with the mandibular canal, were assessed using axial and cross-sectional, 2-dimensional CBCT images. The sizes of the mental and accessory mental foramina were measured and statistically analyzed. Also, the distance between the mental and accessory mental foramina was measured., Results: The accessory mental foramen was observed in 7% of patients. There was no significant difference regarding the sizes of the mental foramen between accessory mental foramen presence and absence. Also, the mean distance between the mental and accessory mental foramina was 6.3 mm (SD: 1.5 mm)., Conclusion: The accessory mental foramen, which shows continuity with the mandibular canal, could be observed in 7% of the subjects using CBCT.

Objective: The objective of this study was to assess the accuracy and reproducibility of cone-beam CT measurements of specific distances around the mandibular canal by comparing them to direct digital caliper measurements., Methods: Six formalin-fixed hemimandible specimens were examined using the ILUMA cone-beam CT system. Images were obtained at 120 kVp, 3.8 mA, and a voxel size of 0.2 mm, with an exposure time of 40 seconds. Specimens were cut into sections at 7 locations using a Lindemann burr, and a digital caliper was used to measure the following distances on both the anterior and posterior sides of each section: Mandibular Width (W); Mandibular Length (L); Upper Distance (UD); Lower Distance (LD); Buccal Distance (BD); and Lingual Distance (LID). The same distances were measured on the corresponding cross-sectional cone-beam CT images using the built-in measurement software. All caliper and cone-beam CT measurements were made by 2 independent trained observers and were repeated after an interval of 1 week. The Bland/Altman method was used to calculate intra- and inter-rater reliability. Intra-class correlation coefficients (ICCs) from 2-way random effects model were calculated. Agreements between cone-beam CT and direct digital caliper were calculated by ICC for 6 distances and 2 observers., Results: Intraobserver and interobserver measurements for all distances showed high agreement. ICCs for intraobserver agreement ranged from 0.86 to 0.97 for cone-beam CT measurements and from 0.98 to 0.99 for digital caliper measurements. ICCs between observers ranged from 0.84 to 0.97 for the cone-beam CT measurements and from 0.78 to 0.97 for the digital caliper measurements. ICCs for cone-beam CT and direct digital caliper ranged from 0.61 to 0.93 for the first observer and from 0.40 to 0.95 for the second observer., Conclusion: Accuracy of cone-beam CT measurements of various distances surrounding the mandibular canal was comparable to that of digital caliper measurements.

Objective: Three-dimensional computed tomography (CT) was used to investigate which skeletodental factors are related to chin point deviation of facial asymmetry in skeletal class III malocclusion (SCIII) patients., Study Design: Forty Korean adult female patients with SCIII, who had a three-dimensional CT taken 1 month before orthognathic surgical surgery, were assigned to group 1 (symmetry) or group 2 (asymmetry) according to the amount of chin point deviation from facial midline. Midfacial, mandibular, and cranial base variables were measured with software and statistically analyzed., Results: Group 2 showed higher positions of the upper canine and first molar, shorter ramus height, more superior-posterior positioning of gonion (Go) on the deviated side, and more mesial inclination of the ramus and medial positioning of Go on the opposite side., Conclusion: Facial asymmetry in SCIII patients occurs due to greater growth and mesial inclination of the ramus and greater maxillary vertical excess in the opposite side.

Objective: The aim of this study was to decide whether use of bicortical screw fixation provides sufficient stability to dispense with intermaxillary fixation (IMF)., Study Design: Eighty-six patients who had undergone surgical setback of the mandible using bilateral sagittal split ramus osteotomies were examined. Group 1 (15 patients) received miniplate fixation with IMF for 6 weeks, and group 2 (71 patients) received bicortical screw fixation and immediate postoperative function. The 2 groups were evaluated radiographically for postsurgical changes of the pogonion 24 months postoperatively., Results: There was no significant difference in the magnitude of the relapse between the 2 groups over the 24-month postoperative period., Conclusion: The use of bicortical screw fixation after sagittal split setback of the mandible provides sufficient stability to dispense with IMF.

Objective: Recent studies suggest that the main blood supply to the bony chin may be through a single arterial branch of the 2 sublingual arteries that anastomose at the midline and penetrate the bone through the lingual foramen, approximately 13 mm from the lower border of the mandible. The objective of this study was to demonstrate the validity of this hypothesis in vivo, to identify clinically the main blood supply to the bony chin, and to measure its parameters: diameter of vessel, direction of flow, and its volume. Materials and method Ultrasound/doppler measurements and periapical radiographs were taken on 20 healthy volunteers, randomly divided into 2 equal groups in order to compare the method's validity. In the first group, the lingual foramen was identified on periapical radiographs and then ultrasound/doppler measurements were performed. In the second group, this procedure was reversed., Results: Positive identification of the lingual foramina on the periapical radiograph was obtained in 13 subjects compared to 20 subjects by ultrasound/doppler examination. Blood volume measurements were obtained in only 17 subjects. The diameter of the artery was 0.18-1.8 mm and the blood flow from 0.7-3.7 mL/min., Conclusions: Ultrasound/doppler imaging is a reliable method to visualize and measure the blood supply to the bony chin. It can become an important tool in presurgical assessment of patients who undergo genioplastic procedures, vestibuloplasty, or insertion of dental implants.