OBJECTIVE: To investigate soft-to-hard tissue response following mandibular reconstruction and to develop a predictive model for projecting soft tissue movement.
METHODS: In this retrospective study, 18 patients receiving mandibular reconstruction using a vascularized iliac flap were enrolled. Various indicators for characterizing the movement of tissues were considered to identify the effective predictors for projecting soft tissue movements. Face-region-specific linear regression models for prediction were constructed and evaluated.
RESULTS: The arithmetic mean of hard tissue movement in an extended area had the strongest correlation with the movement of the focal soft tissue, while the arithmetic mean in a regional area (Ram) was a more effective predictor. The linear regression model using Ram, global extrema and distances between them as the predictors performed the best in the lower margin of the face, with an average error of 1.51 ± 1.38 mm. Soft tissue movement in the alveolar process was not correlated with the existence of dentition, only can be predicted by the soft tissue movement below it. The area of the masseter was strongly correlation with Ram, but no other factors.
CONCLUSIONS: An accurate prediction of soft tissue movements in the lower margin and the alveolar process of the face can be achieved by considering hard tissue and adjacent soft tissue movements. No effective predictor in the masseter area was identified.
CONCLUSIONS: We investigated the relationship between hard tissue movements and the soft tissue responses in the facial area. Through building predictive models for projecting postoperative soft tissue movements, we derive insights for the aesthetic outcome of face surgeries.
BACKGROUND: This study was registered on the Chinese Clinical Trial Registry (registration number: ChiCTR2100054103).

The sagittal split ramus osteotomy (SSRO) carries potential risks and complications. A double-blind, split-mouth, randomized clinical trial was performed, involving 30 patients undergoing mandibular setback. Advanced platelet-rich fibrin (A-PRF) was applied to one side, and the other side served as a control. The volume of postoperative drainage over 24 h was recorded. At 1, 2, and 5 days, and 3 months postsurgery, nerve recovery was assessed using the two-point discrimination test (TPD), while pain was evaluated using a visual analogue scale (VAS pain). Facial swelling was evaluated by taking linear measurements from facial reference points at the same time intervals. In the treatment group, the 24-hour drainage volume was lower (P = 0.011), pain was better on day 5 (P = 0.011), and TPD was better on day 2 (P = 0.011), day 5 (P = 0.007), and 3 months postoperatively (P = 0.020) than in the control group. There was also less facial swelling in the treatment group when compared to the baseline of 3 months postoperative (day 1, P = 0.012; day 2, P = 0.001; day 5, P = 0.011). The difference in bone mineral density (HU) at 3 months between the treatment group (469.7 ± 134.2) and the control group (348.3 ± 127.2) was statistically significant (P = 0.011), in favour of the treatment group. A-PRF may reduce postoperative complications such as neurosensory disturbance of the inferior alveolar nerve, pain, swelling, and drainage while enhancing bone healing in the osteotomy gap following SSRO. TRIAL REGISTRATION: The study was registered with the Chinese Clinical Trial Register (ChiCTR2200064534).

For radical treatment of malignancies in the posterior region of the oral cavity and oropharynx, surgical exposure of the tumor by mandibulotomy is often required. Midline or paramedian vertical mandibulotomies are commonly performed in clinical practice, but these can damage the suprahyoid musculature and genioglossus, and weaken the swallowing and speech function of patients. Stair-stepped mandibulotomy is a new procedure, developed on the principles of functional surgery, that preserves the structure and function of the mandible whilst providing a clear field and avoiding damage to critical muscle attachments. Stair-stepped mandibulotomy is suitable for patients whose primary tumor is located in the middle and posterior part of the tongue or oropharynx, especially if the lesion involves extrinsic tongue muscles. In this case report, we draw on 2 cases of typical patients in our center to elaborate the surgery program design, operation points, advantages and disadvantages of stair-stepped mandibulotomy.

OBJECTIVE: To assess submental-cervical soft tissue changes after en bloc mandibular U-shaped osteotomy and examine alterations in the anterior belly of digastric muscle (ABDM).
METHODS: A retrospective study analyzed 20 patients who underwent en bloc mandibular U-shaped osteotomy from 2018 to 2023. Preoperative (Tp) and long-term follow-up (Tf) CT data were collected for analysis, measuring mandibular volume, soft tissue thickness at menton (Mes) and cervicale (C), and ABDM parameters (length, cross-sectional area (CSA), volume, distance from centroid point to the mandibular margin). Correlation analyses were performed to investigate the connection between soft tissue thickness changes, ABDM changes, and mandibular osteotomy volume.
RESULTS: Long-term follow-up revealed a significant increase in soft tissue thickness at the Mes and C points after U-shaped mandibular osteotomy, especially at the C point. The adaptive length of ABDM decreased, CSA increased, and volume decreased, but the ABDM centroid point shifted downward relative to the mandibular margin, indicating drooping protrusion. The increment of soft tissue thickness was moderately positively correlated with the amount of osteotomy, and the decrement of ABDM length and volume were slightly positively correlated with the amount of osteotomy.
CONCLUSIONS: The degree of soft tissue relaxation after U-shaped osteotomy is related to the extent of osteotomy. Notably, the protrusion of ABDM relative to the mandibular margin affects submental-cervical contour aesthetics. Prior to U-shaped osteotomy, it is crucial to assess the soft tissue condition of the patient\'s lower face, and the individualized design of the osteotomy volume should be carried out cautiously and safely.
METHODS: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

This study presents a combination of 2 different surgery procedures performed on the mandible as part of the treatment aiming to improve the facial profile and occlusal function of patients with severe skeletal class Ⅲ malocclusion and bilateral edentulous gaps. The teeth next to the edentulous gaps were found to be ankylosed. Mandibular setback by bilateral sagittal split ramus osteotomies and mandibular body osteotomies, combined with Le Fort Ⅰ level maxillary advancement were performed, since the chief complaint of the patient was a concave profile. As a result, the skeletal class Ⅲ malocclusion had been corrected, a satisfying facial profile had been achieved, and no apparent adverse effect was found. Thus, it has been proved that the combination of sagittal split ramus osteotomy and mandibular body osteotomy is available for correcting skeletal class Ⅲ malocclusion.

This systematic review aimed to investigate the factors that may contribute to the development of OSA after orthognathic surgery in patients with skeletal class III. Electronic searches of PubMed, Embase, Web of Science, and Cochrane databases were conducted up to December 10, 2022. In total, 277 studies were retrieved and screened according to the inclusion and exclusion criteria, and 14 were finally selected. All studies were of medium quality (moderate risk of bias). The occurrence of OSA after orthognathic surgery in patients with class III skeletal relationships depends on surgical factors and patient self-factors. Surgical factors include surgery type, amount of maxillary and mandibular movement, and the patient\'s postoperative swelling. Patient self-factors include weight, age, gender, and hypertrophy of the soft palate, tonsils, and tongue. According to information in the 14 selected articles, the incidences of OSA after Le Fort I impaction and BSSO setback, BSSO setback, and Le Fort I advancement and BSSO setback were 19.2%, 8.57%, and 0.7%, respectively, mostly accompanied with greater amounts of mandibular recession. However, no clear evidence exists to confirm that orthognathic surgery is a causative factor for postoperative sleep breathing disorders in patients with mandibular prognathism. The wider upper airway in patients with class III skeletal might be the reason for the rare occurrence of OSA after surgery. In addition, obesity and advanced age may lead to sleep apnea after orthognathic surgery. Obese patients should be advised to lose weight preoperatively.

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.
CONCLUSIONS: 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.
BACKGROUND: Chinese Clinical Trial Registry ChiCTR2200061565. Registered on 29 June 2022.

OBJECTIVE: The surgical approach for resection and reconstruction of tongue cancer (TSCC) with or without the lip-splitting incision is controversial. This study introduced a modified approach without lip-splitting and the clinical results were assessed.
METHODS: Sixty-eight TSCC patients underwent surgery using the modified submandibular mandibulotomy (MSMM) approach without lip-splitting, and another matched 68 patients using lip-splitting mandibulotomy (LSM) approach were enrolled in this study. The clinical results including intraoperative relevance and surgical morbidities, survival status, facial appearance and scar scores, function of lower lip, and quality of life (QOL) were evaluated.
RESULTS: The primary tumors were en bloc resected through the MSMM approach with excellent tumor exposure and R0 resection margins as LSM approach. The survival status and complications were similar in both groups. The function of lower lip was better in patients of MSMM group at 1 month after surgery. The MSMM approach was associated with significantly better facial appearance and recreation compared to LSM approach by scar scores and QOL assessment.
CONCLUSIONS: The MSMM approach without lip-splitting achieves similar tumor control, better aesthetic results, and QOL compared to LSM approach. It is a safe and effective surgical approach for patients with TSCC.
CONCLUSIONS: The MSMM approach without lip-splitting is oncological safety in tongue cancer surgery and is scrutinized as one part of the treatment concept for better aesthetic results.

OBJECTIVE: To reveal the change patterns of the facial soft tissue after applying mandibular reconstruction.
METHODS: 16 Patients with mandibular benign tumor were recruited in this retrospective study. For all patients, segmental mandibular osteotomy and concurrent reconstruction using vascularized iliac flap were conducted. The soft tissue thickness of patients\' lower face was measured with CT scans before surgery, 1 week, 6 months and 1 year after surgery. The time-dependent changes of tissue thickness were analyzed.
RESULTS: The most significant tissue swelling was 28.86%, at 1 week after the surgery. The average increase of tissue thickness was 4.78 ± 5.30 mm across patient. After 1 year of the surgery, tissue thickness decreased to the level before operation or the level of the healthy side. The thickness of the low-density tissue fluctuated mildly, while the thickness of the high-density tissue fluctuated significantly. The disuse atrophy of the masseter occurred 1 week after the surgery, and was reversed after 1 year. The removal of the submandibular gland caused depression in submandibular area, which intensified over time.
CONCLUSIONS: Across patients, soft tissue thickness in the lower face after mandibular osteotomy and reconstruction increased significantly 1 week after the surgery, and decreased over time. After 1 year, tissue thickness went back to the pre-surgery level, where matched up with the healthy side.
CONCLUSIONS: We documented the change patterns of the facial soft tissue after mandibular reconstruction. These results can help improve the planning of virtual surgeries and the timing for aesthetic assessment.
BACKGROUND: ClinicalTrials.gov Identifier: ChiCTR2100054103.

This study aimed to assess preoperative radiological and clinical examinations for identifying bone status and to evaluate survival outcomes in patients undergoing marginal mandibulectomy for the primary treatment of oral squamous cell carcinoma. The medical records, enhanced computed tomography (CT) scans, and pathological specimens of these patients were reviewed. Disease-free (DFS), local recurrence-free (LRFS), and osteoradionecrosis-free (ORNFS) survival were analysed. The study included 104 patients. The preoperative CT and clinical examinations achieved a sensitivity of 45.8% and specificity of 100% for judging bone condition. LRFS was 79.6% and DFS was 68.8%. Pathological bone invasion in significantly affected DFS (P = 0.597), while DFS was significantly higher for those with a lower clinical tumour stage (1/2 vs 3/4; P = 0.005) and postoperative radiotherapy (P = 0.011). Among 39 patients receiving postoperative radiotherapy, ORNFS was 75.2%. Postoperative chemotherapy significantly decreased ORNFS (P = 0.009). Tumour subsite (P = 0.003) and the resection site (P = 0.035) significantly affected the remaining bone height. The results indicate that CT and clinical examinations cannot precisely identify superficial bone damage, but work well in selecting patients for marginal resection. Adhering to current indications, this resection approach can guarantee safe bone margins in terms of survival outcomes.