Does Articular Disc Position Change Following Mandibular Setback Surgery?

BACKGROUND: Maintaining condyle position following bilateral sagittal split ramus osteotomy (BSSO) is crucial to minimizing postoperative relapse. However, the impact of BSSO on the articular disc position remains inconclusive. PURPOSE: This study aimed to investigate the changes in articular disc position following setback BSSO surgery. STUDY DESIGN, SETTING, AND SAMPLING: In this prospective cohort study, subjects with mandibular prognathism requiring setback BSSO were enrolled between August 2021 and June 2022 at the Oral and Maxillofacial Surgery Clinic, Faculty of Dentistry, Chiang Mai University, Thailand. Patients with surgical complications, loss of follow-up, or significant artifacts in their MR images were excluded. PREDICTOR/EXPOSURE/INDEPENDENT VARIABLES: The predictor variable was time. The articular disc position was assessed at 3 time points, preoperatively (T0), 3 months postsurgery (T1), and 6 months postsurgery (T2). MAIN OUTCOME: The primary and secondary outcome variables were the changes in articular disc position between T0-T2 and T0-T1, respectively. Articular disc position was coded as normal, anterior disc displacement with reduction (ADDwR), anterior disc displacement without reduction (ADDwoR), and anterior disc displacement without reduction and degenerative joint disease (ADDwoR + DJD). COVARIATES: Covariate variables collected included age (years), sex (male or female), asymmetry (present or absent), surgical procedure (single jaw (BSSO) or bimaxillary surgery), and setback distance (millimeters). ANALYSES: Friedman's test with 80% power and a significance level of 0.05 was employed. Pairwise comparisons were performed using the Dunn-Bonferroni posthoc test to identify statistically significant differences. RESULTS: The study included 16 subjects, 6 females and 10 males, with a total of 32 TMJs. Subjects had a mean age of 23.75 (4.57) years. The proportion of TMJs with normal disc position postoperatively increased from 3 (9.4%) to 19 (59.4%). Statistically significant differences were found in the changes in disc position over time (P < .001). CONCLUSIONS: Following setback BSSO, the articular discs underwent changes, with a majority of ADDwR cases transitioning to a normal position. Cases with ADDwoR also demonstrated disc reduction capability after surgery. The combined orthodontic treatment and setback BSSO appear to have an effect on articular disc position in skeleton class III patients.

Machine Learning Effectively Diagnoses Mandibular Deformity Using Three-Dimensional Landmarks.

BACKGROUND: Jaw deformity diagnosis requires objective tests. Current methods, like cephalometry, have limitations. However, recent studies have shown that machine learning can diagnose jaw deformities in two dimensions. Therefore, we hypothesized that a multilayer perceptron (MLP) could accurately diagnose jaw deformities in three dimensions (3D). PURPOSE: Examine the hypothesis by focusing on anomalous mandibular position. We aimed to: (1) create a machine learning model to diagnose mandibular retrognathism and prognathism; and (2) compare its performance with traditional cephalometric methods. STUDY DESIGN, SETTING, SAMPLE: An in-silico experiment on deidentified retrospective data. The study was conducted at the Houston Methodist Research Institute and Rensselaer Polytechnic Institute. Included were patient records with jaw deformities and preoperative 3D facial models. Patients with significant jaw asymmetry were excluded. PREDICTOR VARIABLES: The tests used to diagnose mandibular anteroposterior position are: (1) SNB angle; (2) facial angle; (3) mandibular unit length (MdUL); and (4) MLP model. MAIN OUTCOME VARIABLE: The resultant diagnoses: normal, prognathic, or retrognathic. COVARIATES: None. ANALYSES: A senior surgeon labeled the patients' mandibles as prognathic, normal, or retrognathic, creating a gold standard. Scientists at Rensselaer Polytechnic Institute developed an MLP model to diagnose mandibular prognathism and retrognathism using the 3D coordinates of 50 landmarks. The performance of the MLP model was compared with three traditional cephalometric measurements: (1) SNB, (2) facial angle, and (3) MdUL. The primary metric used to assess the performance was diagnostic accuracy. McNemar's exact test tested the difference between traditional cephalometric measurement and MLP. Cohen's Kappa measured inter-rater agreement between each method and the gold standard. RESULTS: The sample included 101 patients. The diagnostic accuracy of SNB, facial angle, MdUL, and MLP were 74.3, 74.3, 75.3, and 85.2%, respectively. McNemar's test shows that our MLP performs significantly better than the SNB (P = .027), facial angle (P = .019), and MdUL (P = .031). The agreement between the traditional cephalometric measurements and the surgeon's diagnosis was fair. In contrast, the agreement between the MLP and the surgeon was moderate. CONCLUSION AND RELEVANCE: The performance of the MLP is significantly better than that of the traditional cephalometric measurements.

Temporomandibular Joint Space in Mandibular Prognathism.

This study compared the temporomandibular joint (TMJ) space between patients with normal and prognathic mandibles. The study included a total of 68 Korean individuals, and the TMJ space was measured using computed tomography. Patients with normal SNB values (normal mandible) were classified into Group 1. Patients with high SNB values (prognathic mandibles) were categorized into Group 2. The TMJ space was defined as the distance between the condylar process and the mandibular fossa, and it was significantly different between Groups 1 and 2 (1.94±0.07 mm versus 1.50±0.05 mm, P< 0.01). This study confirmed that the TMJ space in patients with prognathic mandibles is narrower than that in patients with normal mandibles.

The Evaluation of Condylar Position Change in the Asymmetric Mandible Following Sagittal Split Osteotomy.

BACKGROUND: The change of condyle position following orthognathic surgery affects the stability of treatments. This study aims to assess the correlation between the amount of condyles' position change and the severity of mandibular asymmetry following BSSO. MATERIALS AND METHODS: This is a cross-sectional study. Subjects with asymmetric mandibular prognathism following BSSO were studied. Subjects were classified into 2 groups: group 1, subjects had mandibular asymmetry without occlusal cant and underwent BSSO. Group 2, subjects had mandibular asymmetry with occlusal cant and underwent BSSO+ Lefort I osteotomy. The condyle position was evaluated using cone-beam computer tomography (CBCT). Pearson's correlation test was used to assess any correlation between the condyle changes and the change in the mandible in sagittal and anterior-posterior directions. RESULTS: A total of 44 subjects were studied. In group 1, the condyle tilted outward in the deviated condyle and inward in the non-deviated condyle immediately after osteotomy. After 12 months, both condyles showed a rotation relative to the original position. In group 2, the condyles of the deviated sides and non-deviated sides moved inferiorly after surgery (condylar sagging), which was more significant in the non-deviated sides. The condyle rotation was similar to group 1. The severity of asymmetry and occlusal cant correlate with the condylar position change in the two groups. CONCLUSION: The severity of mandibular asymmetry correlates with the amount of condyles' position change immediately after BSSO. However, the condyles tend to return to their original position 12 months later.

Comparison of the skeletal stability after mandibular counter-clockwise rotation in three surgical procedures.

The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2 days (T2), and 12 ± 3 months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.

Tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism.

BACKGROUND: Coordination among lip, cheek and tongue movements during swallowing in patients with mandibular prognathism remains unclear. OBJECTIVES: This study aimed to identify the temporal sequences of tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism and compared characteristics with those of healthy volunteers. METHODS: Seven patients with mandibular prognathism (mandibular prognathism group) and 25 healthy volunteers with individual normal occlusion (control group) were recruited. Tongue pressures and masseter, orbicularis oris, mentalis and supra- and infrahyoid muscle activities while swallowing gel were measured simultaneously using a sensor sheet system with five measurement points and surface electromyography, respectively. Onset time, offset time and durations of tongue pressure and muscle activities were analysed. RESULTS: In the mandibular prognathism group, tongue pressure was often produced first in more peripheral parts of the palate. Offset of tongue pressure in the posteromedian and peripheral parts of the palate and maxillofacial muscle activities except for orbicularis oris were delayed. Duration of tongue pressure in the anteromedian part of the palate was significantly shorter and durations of masseter, mentalis and suprahyoid muscle activities were significantly longer. Times to onset of orbicularis oris and suprahyoid muscle activities based on first onset of tongue pressure were significantly shorter. CONCLUSION: These results suggest that patients with mandibular prognathism may exhibit specific patterns of tongue pressure production and maxillofacial muscle activities during swallowing.

What are the Effects of Internal Fixation on Trigeminal Neurosensory Function and the Temporomandibular Joints Following Intraoral Vertical Ramus Osteotomy?

PURPOSE: Intraoral vertical ramus osteotomy (IVRO) has, traditionally, been accomplished without internal fixation, necessitating a period of maxillomandibular fixation (MMF). With advances in instrumentation, internal fixation of IVRO is feasible, obviating the need for MMF. The purpose is to investigate the effects of transoral internal fixation on the prevalence of third division trigeminal nerve (CNV3) injury, temporomandibular joint (TMJ) arthralgia, and surgical site bleeding following IVRO. MATERIALS AND METHODS: A retrospective study was conducted on patients who underwent IVRO at Vanderbilt University Medical Center between January 2017 and December 2020. The primary predictor variable was fixation status-internal fixation versus MMF. The primary outcome variable was postoperative CNV3 neurosensory disturbance. The secondary outcome variables were TMJ arthralgia and surgical site bleeding. Statistical analysis included Fisher's exact test and McNemar's Chi-squared test. RESULTS: Seventy two subjects (59 IVROs without internal fixation and 65 IVROs with internal fixation) were studied. The frequency of CNV3 neurosensory deficit was 0% in the IVRO without internal fixation group and 3.1% in the IVRO with internal fixation group (P = .49). Within group analysis showed a decreased frequency of postoperative TMJ arthralgia compared to preoperative records in both groups (IVRO without internal fixation group, P = .04 and IVRO with internal fixation group, P = .004). The frequency of active surgical site bleeding controlled with local measures was 1.7% in the IVRO without internal fixation group and 3.1% in the IVRO with internal fixation group (P = 1). CONCLUSION: Internal fixation of IVRO is associated with low incidence of neurosensory deficit, TMJ arthralgia, and active surgical site bleeding.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Improve Facial Appearance?

BACKGROUND: Facial aesthetics may be optimized based on a deeper understanding of soft tissue changes after orthognathic surgery. PURPOSE: The purpose of the study was to delineate facial soft tissue changes after clockwise rotation (CWR) of the maxillomandibular complex (MMC) to correct mandibular prognathism using the surgery-first approach. STUDY DESIGN, SETTING, SAMPLE: This prospective cohort study enrolled patients over 18 years of age with skeletal Class III malocclusion in the craniofacial center. The patients were excluded with previous history of craniofacial syndrome, orthognathic surgery trauma, infection at surgical sites, chin deviation (menton deviation ≥4 mm), 2 or more missing data points after surgery, or without informed consent. This study compared significant facial changes before (T0) and after orthodontic debonding (T1) in the CWR and control groups. PREDICTOR VARIABLE: The patients were divided in accordance with maxillary occlusal plane change (OPC) after surgery into CWR (OPC >4°) and control (OPC ≤4°) groups. MAIN OUTCOME VARIABLE: The primary outcome variable was frontal lip curvature (FLC: Right Cheilion-Stomion-Left Cheilion, degree) with or without upper lip curving upward at T1, where upper lip curving upward was considered more favorable. COVARIATES: The covariates included age, sex, and various cephalometric measurements. ANALYSES: The Mann-Whitney U test, paired, and independent t-test were implemented to compare the intragroup and intergroup differences. Statistical significance was indicated by P value <.05. RESULTS: The study comprised 34 patients (21 women) in the control group and 37 (29 women) in the CWR group; their mean ages were 23.64 ± 4.38 and 24.21 ± 3.84 years, respectively (P value = .562). At T1, the CWR group had significant increased FLC (P value = .001), alar width (P value = .034), and lower vermilion height (P value = .018), and decreased lower lip length (P value = .004). The high FLC group had significant decreased upper lip projection (P value = .002) and increased nasolabial angle (P value = .013). The significant relationship between CWR and high FLC was supported by the χ2 test (P value = .018) and multiple logistic regression (P value = .017). CONCLUSION: Greater CWR of the MMC increased FLC and lower vermilion height and reduced lower lip length. High FLC resulting from the CWR of the MMC improved facial appearance by moving the upper lip curve upward.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Affect Surgical Movement and Stability?

PURPOSE: Orthognathic surgery (OGS) using the surgery-first approach (SFA) can decrease treatment time and increase patient satisfaction. Clockwise rotation (CWR) of the maxillomandibular complex to correct mandibular prognathism leads to optimized functional, aesthetic, and stable outcomes. This study examined the combined effect of SFA and CWR of the maxillomandibular complex to correct mandibular prognathism by comparing the surgical movement before (T0) and immediately after OGS (T1) and the stability between T1 and 12 months after OGS (T2). METHODS: This prospective cohort study enrolled patients with skeletal Class III malocclusion who underwent SFA involving Le Fort I osteotomy and bilateral sagittal split osteotomy, with or without genioplasty. Based on the occlusal plane (OP) change at T0-T1, the patients were divided into CWR (OP > 4°) and control (C) groups (OP ≤ 4°). The predictor variable was OP change at T0-T1. The primary outcome variable was the stability of pogonion (Pog) at T1-T2. The covariates included demographic factors, cephalometric measurements (anterior facial height, posterior facial height, OP, mandibular plane angle, incisor mandibular plane angle, overjet, and overbite), and 3-dimensional landmark displacement (anterior nasal spine, A-point, upper central incisor, upper first molar, lower central incisor, lower first molar, Pog, gonion, and condylion). An independent t-test was used to compare between these 2 groups when appropriate. The level of significance was set at P < .05. RESULTS: The sample included 28 patients (17 females) in the C group and 36 (24 females) in the CWR group; the mean ages were 23.89 ± 3.35 and 24.08 ± 4.02 years, respectively. For the surgical movement at T0-T1, the CWR group showed an association with vertical movement of the maxilla at posterior nasal spine (P = .005), anterior nasal spine (P < .001), and A-point (P < .001) and horizontal backward movement of the mandible at B-point (P < .001), Pog (P < .001), and gonion (P = .042). At T1-T2, all landmarks remained stable without clinically significant difference between the 2 groups. CONCLUSION: Surgical movement in the CWR group could vertically displace the maxilla and setback mandible more than that in the C group. Postoperative skeletal stability remained the same between the 2 groups at 1 year after OGS.

Comparison of the quality of life changes of patients receiving sagittal split ramus osteotomy or intraoral vertical subsigmoid osteotomy for mandibular prognathism.

OBJECTIVE: To investigate and compare the effect of two orthognathic procedures for mandibular setback, namely, sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), on oral health, mental- and physical health-related quality of life across time. MATERIALS AND METHODS: Patients with mandibular prognathism and planned for orthognathic surgery were recruited in this study. Patients were randomized into two groups (IVRO and SSRO groups). Quality of life (QoL) was assessed with the 14-item Short-Form Oral Health Impact Profile (OHIP-14) and the 36-item Short-Form Health Survey (SF-36) preoperatively (T0), postoperative 2 weeks (T1), 6 weeks (T2), 3 months (T3), 6 months (T4), 12 months (T5), and 24 months (T6). A comparison of OHIP-14 and SF-36 scores between two groups was conducted. RESULTS: Ninety-eight patients (49 SSRO group, 49 IVRO group) participated in this study. There was no significant difference in OHIP-14 scores between SSRO and IVRO throughout the treatment process. SSRO group had significant reduction of OHIP-14 score (i.e., improving oral health-related QoL) since postoperative 2 weeks, whereas IVRO group had significant reduction since postoperative 6 weeks. Starting from postoperative 3 months, the oral health-related QoL of both groups was already significantly better than the baseline level and continued to steadily improve afterwards. For SF-36, both groups had increased physical health summary score starting from postoperative 2 weeks, indicating an early and gradual recovery of physical health-related QoL. The mental health summary score of the SSRO group began to increase from postoperative 2 weeks, but that of the IVRO group only began to increase from postoperative 6 weeks. Patient age at the time of surgery was positively correlated with OHIP scores in the postoperative period. CONCLUSIONS: The study concludes that both SSRO and IVRO contributed to the improvement of QoL in the long term, but oral health- and mental health-related QoL of SSRO groups showed earlier improvement. CLINICAL RELEVANCE: Undergoing orthognathic surgery at early ages is advised, as older age of patients appeared to have worse QoL. TRIAL REGISTRATION: Clinical trial registration number: HKUCTR-1985. Date of Registration: 14 Apr 2015.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion.

OBJECTIVES: This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy. MATERIALS AND METHODS: Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect. RESULTS: A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group. CONCLUSIONS: We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback. CLINICAL RELEVANCE: It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Three-Dimensional Quantitative Assessment of Condylar Displacement and Adaptive Remodeling in Asymmetrical Mandibular Prognathism Patients After Sagittal Split Ramus Osteotomy.

This study was performed to evaluate the condylar displacement and associated condylar remodeling in class III patients following mandibular setback surgery via sagittal split ramus osteotomy (SSRO). The sample comprised of 26 condyles of 13 subjects (mean age of 21.2±2.6 y). We evaluated patients with mandibular prognathism and facial asymmetry who had undergone SSRO for mandibular setback at Korea University Hospital between January 2016 and December 2018. Three-dimensional segmentation of the mandibular condyles was done using the initial cone-beam computed tomography scan and scan taken 12 months postoperatively or later. Quantitative assessments of the 3-dimensional condylar displacement from T0 to T1 and bony remodeling of 8 regions of the condylar head were performed. The correlation between the condylar displacement and condylar head remodeling on the deviated (D) and nondeviated (ND) sides was analyzed. Significant correlations between condylar displacement and surface remodeling were observed in both D and ND condyles. The anteroposterior condylar displacement was significantly different between the D and ND sides (P=0.007). There was no significant difference in condylar remodeling between the 2 sides. Condylar displacement and adaptive remodeling after SSRO varied greatly among individuals. Compared with displacement in the ND condyle, displacement in the D condyle has a greater association with condylar remodeling in both D and ND condyles. There is no significant difference in condylar head remodeling between D and ND condyles.

Change in CT Value at Mandibular Ramus After Mandibular Setback and Advancement Surgery With Bicortical Absorbable Plate Fixation.

PURPOSE: This study aimed to evaluate changes in computed tomography (CT) value of ramus bone after sagittal split ramus osteotomy (SSRO) in class II and class III patients using absorbable plates and screws. PATIENTS AND METHODS: In the retrospective study, the participants were female patients with jaw deformities who underwent bilateral SSRO with Le Fort I osteotomy. Maximum CT values (pixel values) of lateral and medial cortexes at anterior and posterior sites of the ramus were measured preoperatively and 1 year postoperatively by using horizontal planes at the mandibular foramen level (upper level) and 10 mm under the mandibular foramen level (lower level) parallel to Frankfurt horizontal plane. RESULTS: Fifty-seven patients and 114 sides (28 class II: 56 sides and 29 class III: 58 sides) were evaluated. Although CT values decreased at most sites of the ramus cortical bone after 1 year of surgery, they increased at the posterior-medial site at the upper level in class II ( P =0.0012) and the lower level in class III ( P =0.0346). CONCLUSION: This study suggested that bone quality at the mandibular ramus could change after 1 year of surgery, and there could be differences between mandibular advancement and setback surgery.

Application of Surgery-First Approach in Treating Skeletal Dentofacial Asymmetry with Orthognathic Surgery.

BACKGROUND: Skeletal dentofacial asymmetry decreases patient's attractiveness by deteriorating symmetry of facial appearance which is of great significance to individuals. Surgery-first orthognathic approach manifests its advantages of shortening treatment time and improving patient's quality of life. However, current literature on surgery-first approach mainly focuses on treating prognathism, overlooking its efficacy in improving facial symmetry of skeletal dentofacial asymmetry patients. This study aimed to assess SFA's efficacy in improving facial appearance by analyzing morphological features of asymmetric bone and facial soft tissue in a three-dimensional manner. METHODS: Thirty-four patients who received orthognathic surgery in a surgery-first fashion were included. Based on three-dimensional CT reconstruction, bilateral preoperative morphological features and postoperative symmetry of hard tissue were compared respectively. Efficacy of facial soft tissue symmetry restoration was evaluated using root mean square deviation (RMSD). RESULTS: Asymmetric features mainly located in menton, mandibular body length, angulation between ramus and midsagittal plane (MSP), distance between gonion and MSP and so on, which were significantly restored after the whole treatment. RMSD of facial soft tissue surface were significantly declined after the treatment and prognathism was corrected simultaneously if existed. CONCLUSIONS: Surgery-first orthognathic approach is proved to be capable of treating skeletal dentofacial asymmetry effectively and efficiently.

Long-term evaluation of the upper airway following mandibular setback surgery in the patients with mandibular prognathism.

OBJECTIVE: The aim of this study was to evaluate the changes in the upper airway following mandibular setback surgery. METHODS: The patients underwent mandibular setback surgery and cone-beam computed tomography scan data obtained at four time points: before surgery, immediately after surgery, short- and long-term follow-up. Upper airway geometries were segmented and extracted at each time point. Time-averaged airflow through the upper airway was evaluated at each time point. The measurements of airway volume and minimum cross-sectional areas were obtained at four time points. RESULTS: The airway volume and cross-sectional areas of airway significantly decreased immediately after surgery (p = 0.013 for airway volume and 0.016 for cross-sectional area). At short-term follow-up, the decreased airway volume and cross-sectional areas still showed statistically significant difference to original dimension (p = 0.017 for airway volume and 0.006 for cross-sectional area). At long-term follow-up, although there were no statistical significances (p = 0.859 for airway volume and 0.721 for cross-sectional area), the airway volume and cross-sectional areas had increased slightly compared to those at short-term follow-up. CONCLUSIONS: Although the airflow and dimensional parameters of the upper airway worsened following mandibular setback surgery, there was a tendency to gradually recover during long-term follow-up.

Evaluation of alveolar bone changes around mandibular incisors during surgical orthodontic treatment of patients with mandibular prognathism: Surgery-first approach vs conventional orthognathic surgery.

INTRODUCTION: This retrospective study aimed to investigate the alveolar bone changes around mandibular incisors in patients with skeletal Class III malocclusion treated with surgery-first orthognathic approach (SFA) and conventional orthognathic surgery (COS) using cone-beam computed tomography scans. METHODS: Sixty-four patients were divided into 2 groups according to the inclusion of presurgical orthodontic treatment; the SFA group included 32 patients treated without presurgical orthodontic treatment, and the COS group included 32 patients treated with presurgical orthodontic treatment. Cone-beam computed tomography scans were obtained before treatment, after presurgical orthodontic treatment, and after treatment for the COS group and were obtained before and after treatment for the SFA group. The measurements of vertical alveolar bone height and horizontal bone thickness at 4 levels and the alveolar bone area surrounding the mandibular incisors were compared according to the treatment progress and groups. RESULTS: The vertical bone levels and horizontal bone thickness of the labial and lingual sides and the area of the alveolar bone around the mandibular incisors were reduced after treatment in both SFA and COS groups. Vertical bone loss was more prominent than horizontal bone loss after treatment in both groups, and alveolar bone loss was greater on the lingual side than on the labial side. There were no significant differences in alveolar bone changes around the mandibular incisor between the SFA and COS groups. However, the alveolar bone was reduced more in the COS group than in the SFA group. CONCLUSIONS: The results indicate that SFA and COS may trigger degeneration of the alveolar bone around the mandibular incisors after treatment in patients with mandibular prognathism. Careful consideration is needed to avoid iatrogenic degeneration of the periodontal support around the incisors, particularly during presurgical orthodontic treatment.

Urinary microRNAs can predict response to abiraterone acetate in castration resistant prostate cancer: A pilot study.

BACKGROUND: Despite novel agents have been introduced to treat castration resistant prostate cancer (CRPC) during the last decade, up to one-third of CRPC patients face primary resistance to new generation compounds. Therefore, sensitive molecular tools are urgently needed for reliable treatment selection and response prediction. This study aimed to evaluate urinary miRNAs and blood circulating androgen receptor (AR) transcript level as a tool for noninvasive outcome prediction for CRPC patients undergoing abiraterone acetate (AA) therapy. METHODS: Prostate cancer-specific miR-148a, -365, -375, and -429 were analyzed in 129 urine samples collected from 100 CRPC patients before and during AA therapy via quantitative reverse transcription PCR. To test the prognostic value, urinary miRNA levels alone, as well as combined with AR level were associated with progression-free survival (PFS) and overall survival (OS). RESULTS: Level of urinary miR-375 was the highest in CRPC in comparison to noncancerous controls, as well as in combination with miR-429 was predictive for short PFS in AA-treated patients (HR = 2.2, 95% CI: 1.1-4.2, p = 0.023). Especially high prognostic power of all analyzed miRNAs was observed in CRPC cases with high blood AR levels. For PFS prediction a tandem of miR-429 and high AR reached HR of 5.0 (95% CI: 2.2-11.8, p < 0.001), while for prediction of OS the best combination was demonstrated by miR-148a and AR with HR of 3.1 (95% CI: 1.4-7.1, p = 0.006). CONCLUSIONS: Urinary miRNAs could be used as prognostic biomarkers for CRPC patients to predict response to AA therapy, especially for the cases with high blood AR levels.

Genetic effect of single nucleotide polymorphisms in growth hormone receptor gene on the risk of non-syndromic mandibular prognathism in the Korean population.

OBJECTIVES: To evaluate the association of three single-nucleotide polymorphisms (SNPs) of growth hormone receptor (GHR) gene with mandibular prognathism (MP) and relationships between mandibular morphology and GHR gene SNPs in the Korean population. MATERIALS AND METHODS: A total of 325 subjects were divided into two groups based on sagittal maxillomandibular relationship by the lateral cephalography: the MP and control groups. From the SNPs in the GHR gene, three SNPs (rs6180, rs6182 and rs6184) were selected. SNP genotyping was performed using direct sequencing. The craniofacial measurements of lateral cephalography were analysed. RESULTS: We found a lack of association between GHR and MP. However, in the analysis according to the values of cephalometric measurements, rs6180 was significantly associated with ANB, SNB, effective mandibular length and SNMP in females. Additionally, rs6182 and rs6184 were significantly associated with ramal height in males. CONCLUSION: Growth hormone receptor SNPs may affect not only the sagittal development of mandible but also the vertical development of ramal height, and GHR SNPs may gender-differently influence mandibular morphology. This finding supports that the GHR might be susceptible on mandibular morphogenesis in the Korean population.

Does the Levasseur-Merrill Retractor Provide Reliable In Vivo Guidance for the Intraoral Vertical Ramus Osteotomy?

PURPOSE: Levasseur-Merrill retractor (LMR) utilization during the intraoral vertical ramus osteotomy (IVRO) helps initiate the osteotomy approximately 7 mm from the posterior border of the mandible, preventing damage to the inferior alveolar nerve. The purpose of this in vivo study is to evaluate the IVRO placement and the risk of neurosensory deficit (NSD) while using the LMR. METHODS: This prospective case series was conducted at a single tertiary care center. Medical records were reviewed for medical and demographic information. Inclusion criteria were as follows: underwent the IVRO procedure by a single provider from June 2020 to June 2022 and postoperative cone beam computed tomography images. Exclusion criteria were as follows: age less than 16 years, previous mandibular osteotomies, inadequate clinical documentation, or follow-up. The primary outcome variables included the proximal segment width and proximity of the IVRO to the inferior alveolar foramen. The secondary outcome variable was NSD as measured subjectively by 2-point discrimination, sharp versus dull touch, and light touch with von Frey filaments. RESULTS: The 26 subjects (42 operated sides) were 96% female, with an average age of 30.1 years (range 17-54 years). The mean proximal segment width was 10.3 ± 1.7 mm (95% confidence interval: 9.77, 10.83). The mean distance from the posterior border of the inferior alveolar foramen (IAF) to the osteotomy was -0.89 ± 1.7 mm (95% confidence interval: -1.43, -0.35), with negative numbers indicating violation of the IAF. IAF and full bony canal violation occurred in 61.9% and 4.8% of operated sides, respectively. NSD at 6 months postoperatively occurred in the 2 sides that experienced full bony canal violation. CONCLUSIONS: The LMR did not consistently guide the IVRO position within 7 mm from the posterior border of the mandible as previously thought and allows for frequent violation of the IAF. Long-term NSD of the inferior alveolar nerve was infrequent and correlated with violation of the full bony canal.

Two-thirds anteroposterior ramus length is the preferred osteotomy point for intraoral vertical ramus osteotomy.

OBJECTIVES: This study aimed to investigate the mandibular canal of ramus and design a suitable osteotomy line for intraoral vertical ramus osteotomy (IVRO) using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Ninety patients were classified into class I, II, and III skeletal pattern groups. When extended from the horizontal base plane (0 mm, mandibular foramen [MF]), with a 2-mm section interval, to 10 mm above and 10 mm below the MF, the following landmarks were identified: external oblique ridge (EOR), posterior border of the ramus (PBR), and posterior lateral cortex of ramus (PLC): IVRO osteotomy point. RESULTS: In the base plane (0-mm plane), the EOR-PBR distance of class III (34.78 mm) and the IOR-PBR distance of class II (32.72 mm) were significantly higher than those of class I (32.95 mm and 30.03 mm). Compared to the EOR-PLC distance, the designed osteotomy point (two-thirds EOR-PBR length) has a 3.49-mm safe zone at the base plane and ranging from 0.89 mm (+ 10-mm plane) to 8.37 mm (- 10-mm plane). CONCLUSIONS: The position at two-thirds EOR-PBR length (anteroposterior diameter of the ramus) can serve as a reference distance for the IVRO osteotomy position. CLINICAL RELEVANCE: Mandibular setback operations for treating mandibular prognathism mainly include sagittal split ramus osteotomy (SSRO) and IVRO. IVRO has a markedly lower incidence of postoperative lower lip paraesthesia than SSRO. Our design presented a reference point for identification during IVRO, to prevent damage to the inferior alveolar neurovascular bundle.