Prediction of surgery-first approach orthognathic surgery using deep learning models.

The surgery-first approach (SFA) orthognathic surgery can be beneficial due to reduced overall treatment time and earlier profile improvement. The objective of this study was to utilize deep learning to predict the treatment modality of SFA or the orthodontics-first approach (OFA) in orthognathic surgery patients and assess its clinical accuracy. A supervised deep learning model using three convolutional neural networks (CNNs) was trained based on lateral cephalograms and occlusal views of 3D dental model scans from 228 skeletal Class III malocclusion patients (114 treated by SFA and 114 by OFA). An ablation study of five groups (lateral cephalogram only, mandible image only, maxilla image only, maxilla and mandible images, and all data combined) was conducted to assess the influence of each input type. The results showed the average validation accuracy, precision, recall, F1 score, and AUROC for the five folds were 0.978, 0.980, 0.980, 0.980, and 0.998 ; the average testing results for the five folds were 0.906, 0.986, 0.828, 0.892, and 0.952. The lateral cephalogram only group had the least accuracy, while the maxilla image only group had the best accuracy. Deep learning provides a novel method for an accelerated workflow, automated assisted decision-making, and personalized treatment planning.

Relapse patterns of two-jaw surgical correction in patients with skeletal Class III malocclusion and different vertical facial types.

The aim of this study was to evaluate postoperative relapse after the surgical correction of skeletal Class III deformities of various facial patterns as a guide to surgical planning. A retrospective cohort study of 90 consecutive patients with skeletal Class III malocclusion who underwent bimaxillary surgery was performed. The surgical outcomes and postoperative stability were compared. The primary predictor variable was vertical facial type, which was classified into three groups according to the Frankfort mandibular plane angle (FMA). The primary outcome of angular and linear measurements was obtained using serial cone beam computed tomography scans obtained at time points of preoperative, 1 week after surgery, and orthodontic debonding. No significant difference in skeletal relapse was observed in patients with the different vertical facial types. The mandible displayed a forward and upward relapse in all three groups postoperatively. The patients with a low FMA exhibited a more consistent mandibular relapse pattern than those with a normal or high FMA. These findings suggest that bimaxillary surgery is clinically stable for mandibular prognathism regardless of the vertical facial pattern. However, 1-1.5 mm of overcorrection in the mandible setback should be considered in patients with a low FMA, because of the greater facial depth and consistent forward and upward mandibular relapse pattern.

Penetration of inferior alveolar nerve canal increased by bicortical fixation after bilateral sagittal split osteotomy in mandibular prognathism.

The purpose of this three-dimensional cone beam computed tomography (CBCT) study was to identify the difference between monocortical fixation (MCF) and bicortical fixation (BCF) in mandibular canal penetration after bilateral sagittal split osteotomy (BSSO) to correct mandibular prognathism, where interosseous fixation was done by BCF or MCF. CBCT was performed 1 week postoperatively and Dolphin 3D software was used to assess direct penetration of the mandibular canal by either type of screw. The primary outcome variable was the presence or absence of mandibular canal penetration and was categorized as a binary coded variable. The BCF and MCF groups were compared by χ2 test, and the odds ratio for canal penetration was estimated. Multiple logistic regression was performed to identify factors related to canal penetration. A total of 118 patients were included. The MCF group had only 6% canal penetrations (3/50 patients) and the BCF group had 58.8% canal penetrations (40/68 patients). The regression model showed that BCF was the only factor causing mandibular canal penetration, with an adjusted odds ratio of 52.5. Awareness of the increased risk of canal penetration with BCF and potential nerve injury might influence case selection.

Outcome of surgical-orthodontic treatment in hemifacial microsomia with and without early mandibular distraction osteogenesis.

The aim of this study was to compare the outcomes of surgical-orthodontic treatment between hemifacial microsomia (HFM) patients who had and had not undergone early mandibular distraction osteogenesis (DO). Twenty adult unilateral HFM patients were included, seven who had undergone early mandibular DO (DO group) and 13 who had not (NDO group). All patients were type IIB, except for one type IIA patient in the NDO group. Mean age at definitive surgery was 20.72±2.96 years. Linear, cross-sectional, and volumetric measurements were obtained from serial cone beam computed tomography scans. Data were obtained pre-surgery (T0), 1 week after surgery (T1), and at treatment completion (T2) to determine surgical movement, post-surgical stability, and net gain movement. Surgical and ultimate outcomes did not differ significantly between the groups. The overall surgical movement among all patients was as follows (mean values): maxillomandibular complex (MMC) symmetry was achieved by Le Fort I differential roll movement (3.78mm extrusion on the affected side, 4.28mm impaction on the non-affected side), a combination of medial movement and yaw rotation of MMC, and genioplasty. Upper and lower dental midlines and deviated menton were shifted by 5.73mm, 5.08mm, and 12.38mm, respectively. Anterior impaction and advancement with counterclockwise rotation of MMC were also performed. Menton was advanced by 6.14mm and lower facial height was increased by 3.55mm. Neither group exhibited a significant difference in stability. Relapse at the maxilla was <1mm and relapse at the mandible was <1.5mm. The results suggest that early DO had limited beneficial effects on the definitive correction outcome. HFM patients achieved acceptable symmetry and a stable surgical outcome, regardless of early DO, following surgical-orthodontic correction at skeletal maturity with three-dimensional surgical simulation.

Does two-dimensional vs. three-dimensional surgical simulation produce better surgical outcomes among patients with class III facial asymmetry?

The aim of this study was to compare the outcomes of traditional two-dimensional planning (2DP) and three-dimensional surgical simulation (3DS) in the surgical correction of skeletal class III with facial asymmetry. This retrospective cohort study included 37 consecutive adult Taiwanese patients. Preoperative and postoperative three-dimensional cephalometric measurements were obtained from cone beam computed tomography scans. The outcome variables were the differences in preoperative and postoperative linear and angular measurements and the differences between the two groups after surgery. When the surgical result was compared between the 2DP and 3DS groups, significant differences were found for four cephalometric variables: the distance from gonion on the non-deviated side to the midsagittal plane (MSP), mid-gonion to the MSP, upper first molar on the non-deviated side to the Frankfort horizontal plane, and the yaw angle. In the 3DS group, mandibular symmetry was achieved because the centre between the bilateral gonions was improved, and because there was no significant difference in the horizontal gonion (Go to the MSP) between the deviated and non-deviated sides after surgery. 3DS provides all the necessary information for planned surgical movements for the correction of facial asymmetry; it should be considered during surgical planning to improve surgical outcomes, particularly the achievement of bilateral mandibular contour symmetry.

Dentoskeletal parameters related to visual perception of facial asymmetry in patients with skeletal class III malocclusion after orthognathic surgery.

The purpose of the study is to explore the critical parameters determining the visual perception of postoperative facial symmetry. This study retrospectively included 24 patients with skeletal class III malocclusion and double-jaw orthognathic surgery (OgS). The patients were classified according to the outcome of subjective visual perception scores (SVPS) based on the postoperative frontal images by 10 orthodontists: symmetrical surgical outcome (S group, n=12) and facial asymmetry after surgery (A group, n=12). The 3D dentofacial measurements from cone beam computed tomography, were compared between the S and A groups. The relationship of all variables in all patients with the SVPS was explored by Spearman correlation coefficient. Significant differences were observed in the midline parameters in the mandible, the B point, gnathion and menton, and the mandibular border axis as well as in the discrepancy of the chin morphology between the two groups (P<0.05). The findings demonstrated that the midline parameter deviation, shape of the mandibular border, and the contour of menton morphology play the major role in the visual perceptions of postoperative asymmetry.

Comparison of the adult three-dimensional craniofacial features of patients with unilateral craniofacial microsomia with and without early mandible distraction.

This study was conducted to analyze the long-term facial growth of patients with craniofacial microsomia (CFM) after early mandible distraction osteogenesis (DO), and compared adult three-dimensional (3D) craniofacial features of patients with and without early mandibular DO for Pruzansky grade II deformities. The study included 20 patients: 9 with early mandible DO (the DO group) and 11 without previous treatment (the NDO group). Longitudinal radiographs were measured for growth changes after DO. The 3D craniofacial images were constructed to compare the craniofacial forms between the two groups. The patients with early DO presented 8 to 9mm forward and downward maxillary growth and 4.6mm limited forward and 17.3mm substantial downward mandibular growth. The ramus length ratio (affected/nonaffected) was 90.8% at DO completion and decreased to 69.5% at growth completion during 13 years of follow-up. Both groups showed obvious craniofacial asymmetry, as indicated by occlusal plane canting, chin deviation, transverse and vertical condyle positions, and mandibular contours. Although all the bilateral differences were higher in the NDO group than in the DO group, no statistical differences were found. Early mandible distraction could not alter the inherent facial growth pattern in patients with grade II CFM. Limited changes are derived for definitive facial correction with early DO.

Effects of two alar base suture techniques suture techniques on nasolabial changes after bimaxillary orthognathic surgery in Taiwanese patients with class III malocclusions.

A randomized controlled trial was designed to assess the effectiveness of two alar base cinch techniques on the changes in nasolabial morphology after bimaxillary orthognathic surgery. Sixty patients requiring a Le Fort I osteotomy to correct skeletal discrepancies were selected randomly to receive either conventional or modified alar base cinching during the intraoral wound closure procedure. Conventional cinching passed through nasalis muscle and anterior nasal spine. Modified cinching also passed through dermis tissue to increase the anchorage. Postoperative hard and soft tissue changes were evaluated using cone beam computed tomography and three-dimensional stereophotogrammetry at predefined time points. Forty-eight patients with a skeletal class III malocclusion were included. In the conventional group, there was an increase of 0.31 ± 1.31 mm in nasal width and an increase of 0.97 ± 1.60mm in columellar length. In the modified group, there was an increase of 0.81 ± 1.87 mm in the cutaneous height of the upper lip and a decrease of 0.76 ± 1.56 mm in lower prolabial width. Patients with an initial narrow nasal width, alar base width, and less vertical nostril show were more susceptible to a greater degree of change after surgery. Both alar base suture techniques are effective at controlling nasolabial form changes resulting from class III dual-jaw orthognathic surgery.

Fronto-facial monobloc distraction in syndromic craniosynostosis. Three-dimensional evaluation of treatment outcome and facial growth.

The objectives of this study were to investigate the treatment effect and stability of fronto-facial monobloc distraction osteogenesis. Five consecutive patients who underwent monobloc distraction were included (aged 4.8-18.4 years). Three patients had Crouzon syndrome, one had Apert syndrome, and one had Pfeiffer syndrome. The evaluation included clinical records, serial cephalograms for at least 1-year follow up (average 24.6 months). The treatment and post-treatment changes were measured. The intracranial volume, upper airway volume and globe protrusion were calculated from CT before and after treatment. After distraction, the supraorbital region was advanced 15.3mm forward, the midface demonstrated forward advancement of 17.7 mm, 22.1mm and 23.1mm at orbitale, anterior nasal spine and A point, respectively. The downward movement was 2-3mm at maxillary level. The intracranial volume increased 11%; the upper airway volume increased 85% on average. Globe protrusion reduced 3.7 mm on average, which was 20% of underlying skeletal movement. Facial growth demonstrated forward remodelling of the supraorbital region, mild downward but no further forward growth of the midface. Monobloc distraction is effective for relieving related symptoms and signs through differential external distraction at different vertical levels of the face.

The stability of mandibular prognathism corrected by bilateral sagittal split osteotomies: a comparison of bi-cortical osteosynthesis and mono-cortical osteosynthesis.

This study evaluated the differences in surgical changes and post-surgical changes between bi-cortical and mono-cortical osteosynthesis (MCO) in the correction of skeletal Class III malocclusion with bilateral sagittal split osteotomies (BSSOs). Twenty-five patients had bi-cortical osteosynthesis (BCO), 32 patients had mono-cortical fixation. Lateral and postero-anterior cephalometric radiographs, taken at the time of surgery, before surgery, 1 month after surgery, and on completion of orthodontic treatment (mean 9.9 months after surgery), were obtained for evaluation. Cephalometric analysis and superimposition were used to investigate the surgical and post-surgical changes. Independent t-test was performed to compare the difference between the two groups. Pearson's correlations were tested to evaluate the factors related to the relapse of the mandible. The sagittal relapse rate was 20% in the bi-cortical and 25% in the mono-cortical group. The forward-upward rotation of the mandible in the post-surgical period contributed most of the sagittal relapse. There were no statistically significant differences in sagittal and vertical changes between the two groups during surgery and in the post-surgical period. No factors were found to correlate with post-surgical relapse, but the intergonial width increased more in the bi-cortical group. The study suggested that both methods of skeletal fixation had similar postoperative stability.

Alveolar bone grafting in the treatment of midline alveolar cleft and diastema in incomplete median cleft lip.

Median cleft lip is a rare congenital anomaly. The wide diastema with mesial tipping observed in these patients has been largely overlooked. A midline submucosal alveolar cleft prevents adequate treatment. The purpose of this article is to describe an alveolar bone grafting (ABG) technique used in the combined surgical-orthodontic approach to diastema treatment in patients presenting with incomplete median cleft lip. Patients treated for incomplete median cleft lip and diastema were identified in the clinic registry from 1981 to 2007. Six patients were identified; 4 underwent ABG before permanent maxillary incisor eruption, the other 2 were seen later when they were 11 years old. All 6 ABGs were successful. The incisors erupted through the graft or were successfully moved into it with lasting results. Follow-up ranged from 8 to 21 years. The existence of a midline submucosal alveolar cleft and subsequent diastema should be recognized and addressed in all patients who present with incomplete median cleft lip repair. This includes taking maxillary occlusal view X-rays before the age of 5 years to detect the cleft, and proceed to ABG if necessary, generally before permanent maxillary incisor eruption.