The Skeletal Stability of Combined Surgery First Approach and Clear Aligners in Skeletal Class III Malocclusion Correction: A Randomized Controlled Trial

The surgery first approach (SFA) and clear aligners technique can address traditional treatment defects, such as prolonged waiting times for surgery and a less desirable facial appearance due to wire aligners. However, the curative effect of the combination remains uncertain. The randomized controlled study aimed to evaluate the skeletal stability of the SFA compared to the conventional orthodontic first approach (OFA), both of which were applied with clear aligners. A total of 74 participants were randomly allocated to two groups: the SFA group (experimental) and the OFA group (control). The skeletal deviation was calculated using reconstruction models from computed tomography scans taken immediately and 6 months after surgery. The largest median deviations were detected in the y-axis of the mandible for both two groups, separately 1.36 mm in the experimental group and 1.19 mm in the control group. Apart from the maxillary yaw dimension (p = 0.005), there were no significant differences between the two groups in terms of linear and angular deviation. The experimental group had an overall treatment time of 18.05 ± 2.53 months, while the control group took 22.83 ± 3.60 months (p < 0.05). Therefore, the combined surgery-first and clear aligners treatment can achieve comparable skeletal stability to the conventional approach, while also saving significant time.

Three-Dimensional Evaluation of Skeletal Stability following Surgery-First Orthognathic Approach: Validation of a Simple and Effective Method

Background  The three-dimensional (3D) evaluation of skeletal stability after orthognathic surgery is a time-consuming and complex procedure. The complexity increases further when evaluating the surgery-first orthognathic approach (SFOA). Herein, we propose and validate a simple time-saving method of 3D analysis using a single software, demonstrating high accuracy and repeatability. Methods  This retrospective cohort study included 12 patients with skeletal class 3 malocclusion who underwent bimaxillary surgery without any presurgical orthodontics. Computed tomography (CT)/cone-beam CT images of each patient were obtained at three different time points (preoperation [T0], immediately postoperation [T1], and 1 year after surgery [T2]) and reconstructed into 3D images. After automatic surface-based alignment of the three models based on the anterior cranial base, five easily located anatomical landmarks were defined to each model. A set of angular and linear measurements were automatically calculated and used to define the amount of movement (T1-T0) and the amount of relapse (T2-T1). To evaluate the reproducibility, two independent observers processed all the cases, One of them repeated the steps after 2 weeks to assess intraobserver variability. Intraclass correlation coefficients (ICCs) were calculated at a 95% confidence interval. Time required for evaluating each case was recorded. Results  Both the intra- and interobserver variability showed high ICC values (more than 0.95) with low measurement variations (mean linear variations: 0.18 mm; mean angular variations: 0.25 degree). Time needed for the evaluation process ranged from 3 to 5 minutes. Conclusion  This approach is time-saving, semiautomatic, and easy to learn and can be used to effectively evaluate stability after SFOA.

Comparison study of the Le Fort I osteotomy using 2- and 4-plate fixation

This study was conducted to evaluate the postsurgical stability of Le Fort I osteotomy using zygomatic buttress internal fixation alone with no piriform aperture internal fixation. Patients with maxillary retrognathia and mandibular prognathism underwent the Le Fort I osteotomy with a bilateral sagittal split ramus osteotomy. In group I, fixation was accomplished using titanium plate and screws placed at the piriform aperture and the zygomatic buttress (4 plates). In group II, fixation was accomplished using titanium plate and screws placed at the zygomatic buttress (2 plates). Lateral cephalometric radiographs were taken preoperatively (T1), immediately after surgery (T2), and at 6 months to 1 year (T3) to evaluate skeletal movement. In total, 32 patients were included in this study. None of the patients had wound infection, dehiscence, bone fragment instability, and long-term malocclusion. Regarding point A and the posterior nasal spine (PNS), vertical and horizontal relapse in groups I and II did not differ significantly. In most hospitals, the maxilla was fixed using four plates (piriform aperture and zygomatic buttress); however, within the limitations of the study, the choice of the number of plates for osteosynthesis following Le Fort I osteotomy and repositioning of the maxilla can be left to the discretion of the surgeon without putting the patients at risk for increased relapse by careful intraoperative management.

Skeletal Stability after Mandibular Setback via Sagittal Split Ramus Osteotomy Verse Intraoral Vertical Ramus Osteotomy: A Systematic Review

Purpose: The purpose of present study was to review the literature regarding the postoperative skeletal stability in the treatment of mandibular prognathism after isolated sagittal split ramus osteotomy (SSRO) or intraoral vertical ramus osteotomy (IVRO). Materials and Methods: The articles were selected from 1980 to 2020 in the English published databases (PubMed, Web of Science and Cochrane Library). The articles meeting the searching strategy were evaluated based on the eligibility criteria, especially at least 30 patients. Results: Based on the eligibility criteria, 9 articles (5 in SSRO and 4 in IVRO) were examined. The amounts of mandibular setback (B point, Pog, and Me) were ranged from 5.53–9.07 mm in SSRO and 6.7–12.4 mm in IVRO, respectively. In 1-year follow-up, SSRO showed the relapse (anterior displacement: 0.2 to 2.26 mm) By contrast, IVRO revealed the posterior drift (posterior displacement: 0.1 to 1.2 mm). In 2-year follow-up, both of SSRO and IVRO presented the relapse with a range from 0.9 to 1.63 mm and 1 to 1.3 mm respectively. Conclusion: In 1-year follow-up, SSRO presented the relapse (anterior displacement) and IVRO posterior drift (posterior displacement). In 2-year follow-up, both of SSRO and IVRO showed the similar relapse distances.

Skeletal stability after sagittal split ramus osteotomy with physiological positioning in patients with skeletal mandibular prognathism and facial asymmetry

The correction of deformities of the jaw in patients with facial asymmetry is challenging because of the high rate of relapse, which may partly be caused by skeletal interference and inappropriate seating of the condylar head. We evaluated outcomes in 30 patients who were treated by short lingual osteotomy with physiological positioning. Nine had facial symmetry (absolute displacement of the menton<2mm), 14 had minor asymmetry (displacement of >2 to <4mm), and 7 severe asymmetry (displacement of >4mm). The postoperative position of the menton (Me) was stable in each group, but deviated by 3.56mm in those with severe asymmetry. This deviation remained immediately after operation and after more than one year in this group, which implies that the Me was not on the mandibular midline. The lateral swing of both sides of the proximal segment did not change immediately after operation in any group. Although short lingual osteotomy with physiological positioning can result in skeletal stability, it is important to assess the association between the dental arch and the mandible using computed tomography to ensure a good outcome in patients with a skeletal class III deformity and facial asymmetry.

Are bicortical screw and plate osteosynthesis techniques equal in providing skeletal stability with the bilateral sagittal split osteotomy when used for mandibular advancement surgery? A systematic review and meta-analysis

The objective of this study was to perform a systematic review and meta-analysis to test the null hypothesis that there is no difference in postoperative skeletal stability between bicortical screw and monocortical plate fixation after mandibular advancement surgery with bilateral sagittal split ramus osteotomy (BSSO). A comprehensive search of major databases (PubMed, EMBASE, and Cochrane CENTRAL) was conducted to locate all relevant articles published from inception to October 2015. Studies were selected based on inclusion criteria; randomized controlled trials, controlled clinical trials, and retrospective studies comparing bicortical screw vs. monocortical plate fixation after BSSO, reported in peer-reviewed publications in the English language, were considered eligible. Changes in linear measurements (horizontal and vertical) were analyzed. Five relevant studies were identified, involving 203 patients (bicortical screw n=98, monocortical plate n=105). No significant difference was found between monocortical plate and bicortical screw fixation in horizontal (P=0.099) or vertical measurement (P=0.882). Based on this review, there is overall agreement in the literature that the amount of advancement has a direct relationship with postoperative changes. The results of this meta-analysis support the hypothesis that there is no statistically significant difference in skeletal stability between bicortical screw and monocortical plate fixation of the BSSO following mandibular advancement surgery.

Skeletal stability after bilateral sagittal split advancement and setback osteotomy of the mandible with miniplate fixation

The purpose of this study was to evaluate intraorally placed mini plates and monocortical screws in terms of postoperative skeletal stability after bilateral sagittal split advancement and setback osteotomy of the mandible. Ten patients were included in this study with five requiring advancement (group I) and five requiring setback of the mandible (group II). Bell and Epker modified surgical technique was followed for all the patients. All the patients underwent pre- and postsurgical orthodontics. Cephalometric radiographs were taken preoperatively, immediate, 3, 6, and 12 months postoperatively. Cephalometric tracings were performed by one individual examiner using a modified burstone analysis. Statistical analysis was performed using the student paired t-test. In advancement patients, SNB (sella, Nasion, B point) angle showed relapse at 12th month postoperative period which was statistically significant (2.4 degrees). No changes were observed in anterior facial height, posterior facial height, Frankfort-mandibular incisor angle (FmiA), and overjet during the follow-up period. In setback patients, posterior facial height (p < 0.05), angles between the lower incisors and mandibular plane and pogonion had a statistically significant change position of 1.4 mm (paired t-test, p = 0.03). The SNB angle, anterior facial height, interincisal angle, and FmiA remained constant (0.8-1.2 degrees) during the follow-up period. In advancement cases, the relapse was seen from the third month postoperative period but in setback cases, the relapse was noted from the sixth month onward and the skeletal relapse in these cases were noticed cephalometrically.