Study Objectives: The mandibular advancement device (MAD) is a treatment option for obstructive sleep apnea (OSA). The goal is to analyze and determine changes in the position of dental and skeletal structures between cone beam computed tomography (CBCT) images obtained from patients currently using the MAD as a treatment modality for OSA. Materials and Methods: Eighteen patients underwent CBCTs for MAD treatment. Landmarks were placed in different structures and distances/angles were calculated. Reliability was done measuring CBCT images of five patients three times. Descriptive statistics, repeated-measures analysis of variance, and paired t-test were used. Results: Landmarks presented excellent reliability, the lowest being the z-axis of the rightmost anterior-superior part of the coronoid process (intraclass correlation coefficient = 0.854). The largest mean change in distance was from the buccal furcation of 17 to 47 (-6.66+/--6.66mm). The largest mean change in angle was 27 buccal furcation-left lingula-left hyoid bone (-16.83+/-27.30°). There is a mean distance change of 0.55 mm and a mean angular change of 13.11° of all linear distances and angles assessed. Conclusions: Vertical linear skeletal changes with placement of a MAD include a vertical increase of the mandible relative to the maxilla and a superior movement of hyoid bone relative to the mandible. AP linear changes include mandibular protrusion and anterior movement of the hyoid bone relative to the cervical vertebrae, and an anterior movement of the hyoid bone relative to the maxilla. Angular movements include the rotation of the hyoid bone anterosuperiorly. Skeletal repositionings should be correlated with patient symptoms to determine whether short-or long-term usage of the MAD is indicated for patients. Assessing specific tendencies with the use of the MAD will help clinicians to also predict outcomes of skeletal changes to ultimately decide the best candidates for this type of treatment.

Objective Compare measurements of skeletal and dental areas on the CBCT to the corresponding soft-tissue measures taken from a 3D Facial Scanner. Methods 30 patients with CBCT and 3D Facial scanner photos were selected from the orthodontic program database. 30 different distance measurements were obtained from CBCT and facial scan. OrthoInsight software was used to obtain the measurements from the facial scan images, and AVIZO software was used for corresponding CBCT landmarks. The Euclidean distance formula was used to determine the distances for the corresponding x, y, and z coordinates of the CBCT. Reliability for CBCT and Facial Scanner was completed by calculating 30 distances for 10 patients, 3 times. Once reliability was determined, all 30 distances were calculated once for CBCT and facial scanner on each patient and descriptive statistics and paired t-test were applied. Results All distances measured presented excellent reliability, the lowest one being the left eye width for the facial scanner (ICC 0.847). The landmark with the highest mean error on the CBCT was 2.0 ± 1.6 mm on the z-axis for the spinal level landmark. The Facial Scanner's largest mean measurement error was 1.5 ± 0.9 mm for the distance of the left corner of the mouth to gonion. All data except width between outer eye corners were statistically significant (p < 0.05). The average differences between facial scan and CBCT measurements ranged between 0.77 mm (left canine to cheekbone) to 26.94 mm (left subnasale to gonion) and are thus comparable. All measurements show a reasonable standard deviation between 2.57 mm (left eye width) to 9.91 mm (left gnathion to EAM). Conclusion Distances obtained from CBCT and facial scan present mild differences giving the perspective of a relationship between them. Understanding this difference and relationship can make it plausible to expect certain underlying skeletal distances under soft-tissue structures.