Three-Dimensional Anthropometric Facial Analysis and Fitting Discrepancies Between Stereophotogrammetry and CT.

BACKGROUND: The reliability and repeatability of stereophotogrammetry and CT in 3-dimensional anthropometric facial analysis were investigated in this study, which also explored the clinical application of supine CT. METHOD: In this study, 3D CT and 3dMD stereophotogrammetry were used on 20 healthy volunteers. The fitting distance between stereophotogrammetry and CT scans at landmark points was measured, along with facial feature measurements (Al-Al) face width (Go-Go, Zy-Zy, Ex-Ex), and hemi-face height (Sn-Gn). The intraclass correlation coefficient (ICC) was employed to assess interrater agreement and to verify the reliability of the measurement methods. Paired t -analysis was utilized for analyzing intramethod displacement. RESULTS: The alare, nasion, and pronasale points were found to be minimally influenced by different positions and are more recommended as landmark points for registration. CT demonstrated good interrater reliability on all indicators. In stereophotogrammetry, measurements for Go-Go and Zy-Zy displayed an interclass correlation coefficient (ICC) of less than 0.75. Significant differences between the 2 methods were observed for En-En, Ex-Ex, and Go-Go ( P < 0.05). Specifically, CT analysis for Go-Go showed a measurement 2.34 mm larger than that obtained with the 3dMD method. CONCLUSION: Both CT and stereophotogrammetry were found to be reliable methods for evaluating facial soft tissue. It is speculated that Go-Go measurement is primarily influenced by factors such as different positions, facial expressions, and gravity. These variables should be carefully considered during the evaluation of the mandibular angle region.

Correcting facial asymmetry through guided plate assisted mandibular angle osteotomy.

Background: Asian women prefer a smooth and narrowed mandibular appearance. The purpose of the retrospective cohort study is to evaluate guide plate-assisted mandibular angle ostectomy (MAO) in improving mandibular symmetry for Asian female patients with mandibular angle hypertrophy (MAH) with normal occlusal relationship. Methods: We retrospectively examined 11 patients with asymmetry MAH with normal occlusal relationship who received MAO at Shanghai Ninth People's Hospital between September, 2020, and January, 2022. Preoperative plans were designed based on CT data and executed using metal guide plate during the operation. Preoperative and one-week postoperative CT scans were used to assess measurements including Height_Go, Divergence_Go, ∠ZyZy-GoGo, and osteotomy volume, to evaluate symmetry. For precision, compare the postoperative CT with the preoperative design, assessing osteotomy distance, angle, and volume error. Patient satisfacation was evaluated with Likert Scale in 6-month follow-up. Secondary lipofilling procedures were given as appropriate. Statistical analysis was performed using paired t-tests in SPSS. Results: The mean age of the 11 patients was 28.5 years (range 23-34 years). 2 of these underwent lipofilling procedures. No complications were observed during the following-up. Postoperative results were not statistically different from the design, demonstrating a precision of within 2 mm. Height_Go disparity within 5 mm get corrected notably, reducing asymmetry from 15.09% preoperatively to 2.74% postoperatively. Patients satisfaction was rated at 4.5 out of 5 in 6 month follow-up. Conclusions: Guide plate-assisted mandibular angle osteotomies achieve effective and precise surgery. This approach demonstrates a safe option for correction for mandibular asymmetry, achieving patient satisfaction.

Morphological and quantitative study of the inferior alveolar nerve canal in hemifacial microsomia.

This study aimed to probe into the anatomic course of inferior alveolar nerve canal (IANC) in hemifacial microsomia (HFM) on a large scale, morphological observations and further quantitative study were performed. Patients were classified by Pruzansky-Kaban classification. The anatomic course of IANC was analyzed morphologically with three-dimensional (3D) imaging software among 248 patients. Seven distances between fixed landmarks on both sides were measured for 236 patients. The differences between affected and unaffected sides were compared. Significant differences were found in the entrance (P < 0.001), route (P < 0.001), and exit (P < 0.05) of IANC in type IIb and III HFM. The higher the degree of mandibular deformity was, the higher the incidence of IANC variation was (P < 0.05). The distances in the horizontal aspect of IANC including from mandibular foramen to mental foramen (P < 0.05) and from mental foramen to gonion (P < 0.05) were significantly shorter on the affected side. Abnormalities of the anatomical course of IANC exist in patients with Pruzansky-Kaban type IIb and type III HFM. The reduction of IANC on the affected side in the horizontal distance is more obvious. Three-dimensional imaging assessment is recommended before surgery.

Efficacy of navigation system-assisted distraction osteogenesis for hemifacial microsomia based on artificial intelligence for 3 to 18 years old: study protocol for a randomized controlled single-blind trial.

BACKGROUND: Mandibular distraction osteogenesis (MDO) is a major part of the treatment for hemifacial microsomia patients. Due to the narrow surgical field of the intraoral approach, osteotomy accuracy is highly dependent on the surgeons' experience. Electromagnetic (EM) tracking systems can achieve satisfying accuracy to provide helpful real-time surgical navigation. Our research team developed an EM navigation system based on artificial intelligence, which has been justified in improving the accuracy of osteotomy in the MDO in animal experiments. This study aims to clarify the effect of the EM navigation system in improving the MDO accuracy for hemifacial microsomia patients. METHODS: This study is designed as a single-centered and randomized controlled trial. Altogether, 22 hemifacial microsomia patients are randomly assigned to the experiment and control groups. All patients receive three-dimensional CT scans and preoperative surgical plans. The EM navigation system will be set up for those in the experiment group, and the control group will undergo traditional surgery. The primary outcome is the surgical precision by comparing the osteotomy position of pre- and postoperative CT scan images through the Geomagic Control software. The secondary outcomes include mandibular symmetry (occlusal plane deviation angle, mandibular ramus height, and body length), pain scale, and complications. Other indications, such as the adverse events of the system and the satisfactory score from patients and their families, will be recorded. DISCUSSION: This small sample randomized controlled trial intends to explore the application of an EM navigation system in MDO for patients, which has been adopted in other surgeries such as orthognathic procedures. Because of the delicate structures of children and the narrow surgical view, accurate osteotomy and protection of nearby tissue from injury are essential for successful treatment. The EM navigation system based on artificial intelligence adopted in this trial is hypothesized to provide precise real-time navigation for surgeons and optimally improve patient outcomes, including function and aesthetic results. The results of this trial will extend the application of new navigation technology in pediatric plastic surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2200061565. Registered on 29 June 2022.