Three-dimensional virtual planning in mandibular advancement surgery: Soft tissue prediction based on deep learning

The study aimed at developing a deep-learning (DL)-based algorithm to predict the virtual soft tissue profile after mandibular advancement surgery, and to compare its accuracy with the mass tensor model (MTM).Subjects who underwent mandibular advancement surgery were enrolled and divided into a training group and a test group. The DL model was trained using 3D photographs and CBCT data based on surgically achieved mandibular displacements (training group). Soft tissue simulations generated by DL and MTM based on the actual surgical jaw movements (test group) were compared with soft-tissue profiles on postoperative 3D photographs using distance mapping in terms of mean absolute error in the lower face, lower lip, and chin regions.133 subjects were included — 119 in the training group and 14 in the test group. The mean absolute error for DL-based simulations of the lower face region was 1.0 ± 0.6 mm and was significantly lower (p = 0.02) compared with MTM-based simulations (1.5 ± 0.5 mm).ConclusionThe DL-based algorithm can predict 3D soft tissue profiles following mandibular advancement surgery. With a clinically acceptable mean absolute error. Therefore, it seems to be a relevant option for soft tissue prediction in orthognathic surgery. Therefore, it seems to be a relevant options.     

Time matters – Differences between computer-assisted surgery and conventional planning in cranio-maxillofacial surgery: A systematic review and meta-analysis

The aim of the study was to assess if there is a time difference (operative time, ischemia time, planning time and hospitalization) between computer-assisted surgery (CAS) and conventional planning in cranio-maxillofacial surgery. An electronic search was performed in June 2018. Studies comparing time difference between CAS and traditional planning were included. 28 publications were included, with 536 patients in the CAS group and 784 in the control group. 18 studies reported on mandibular/maxillary reconstruction and a meta-analysis was conducted on 15 of these studies. This meta-analysis was undertaken to demonstrate the difference between the groups regarding operative time, ischemia time and hospitalization for mandibular/maxillary reconstruction and showed a decreased operative time for the CAS group with a mean difference of −84.61 min, 95% confidence interval [−106.77, −62,45], p < 0.001. Ischemia time was also decreased, with a mean difference of −36.14 min, 95% confidence interval [−50.57, −21.71], p < 0.001. This systematic review and meta-analysis suggests that CAS is shortening the operative time and ischemia time for mandibular/maxillary reconstruction. It also leads to a reduction in hospitalization. Additionally, CAS seems to shorten the preoperative planning time for orthognathic surgery.     

Surgery-first orthognathic approach for the correction of facial asymmetry

We aimed to compare the reliability of the surgery-first approach and the traditional orthodontic-first approach for the correction of facial asymmetry based on the new classification of facial asymmetry.Patients with facial asymmetry who underwent orthognathic surgery between January 2016 and January 2019 were included. Cephalometric changes and relapse ratios were analyzed 12 months before and after surgery. Patients were divided into horizontal and vertical asymmetry groups based on the asymmetry vector, and subgroup analysis was conducted.The surgery-first approach without presurgical orthodontic treatment and the orthodontic-first approach showed a similar degree of asymmetry correction and skeletal stability. The relapse ratios of the maxilla height in the surgery-first and orthodontic-first groups were 0.25 ± 0.21 and 0.27 ± 0.25, respectively (p = 0.63), the relapse ratios of the maxilla width were 0.31 ± 0.32 and 0.21 ± 0.2, respectively (p = 0.14), the mandibular height relapse ratios were 0.34 ± 0.58 and 0.29 ± 0.36, respectively (p = 0.69), and the mandibular width relapse ratios were 0.12 ± 0.22 and 0.26 ± 0.31, respectively (p = 0.058). The treatment period of the surgery-first group (18.5 ± 5.3 months) was significantly shorter than that of the orthodontic-first group (22.9 ± 7.5 months, p = 0.024). Among the surgery-first group, patients with vertical asymmetry (15.0 ± 3.2 months) had a shorter treatment than those with horizontal asymmetry (21.6 ± 6.8 months, p = 0.006).Although contesting traditional standards is always challenging, the surgery-first orthognathic approach may lead to a new era in traditional orthognathic approaches. This new classification of facial asymmetry could be useful and practical when treating patients with facial asymmetry regardless of the etiology.     

Influence of filler geometry and viscosity of composite luting materials on marginal adhesive gap width and occlusal surface height of all-ceramic partial crowns

ObjectivesTo evaluate the influence of filler geometry and viscosity of luting composites on marginal adhesive gap width (MGW) and occlusal surface height (OSH) of all-ceramic partial crowns.MethodsForty-eight all-ceramic partial crowns (Celtra Duo, Dentsply) were created and divided into six groups (n = 8). Restorations were bonded using universal adhesive (Prime & Bond Active, Dentsply) in combination with low-viscosity composites (LV) containing amorphous fillers (Calibra Ceram, Dentsply) (LV-AF), heterogeneous fillers (Tetric EvoFlow, Ivoclar Vivadent) (LV-HF) vs. high-viscosity composites (HV) containing spherical fillers (Ceram.x, Dentsply) (HV-SF) or heterogeneous fillers (Tetric EvoCeram, Ivoclar Vivadent) (HV-HF). HV materials were used either with or without sonication. MGW [µm] was measured by SEM. Displacements of the restorations after luting, such as changes (Δ) in OSH [µm], tilting and rotation [°], were measured using a dial gauge and 3D-analytical software (OraCeck, Cyfex). Statistical analysis was by Mann-Whitney U-test and t-test with α = 0.05.ResultsMGW (p = 0.002) and tilting (p = 0.001) were significantly smaller with LV (228.0 ± 112.35 µm; 0.89 ± 1.25°) than with HV (338.1 ± 97.26 µm; 1.95 ± 1.26°). Sonication had no effect on MGW in HV-HF (332.32 ± 91.39 µm) and HV-SF (343.85 ± 105.48 µm; p = 0.74). Sonication decreased ΔOSH by ~50% with HV-SF (64.21 ± 27.90 µm) but remained unchanged with HV-HF (39.06 ± 14.08 µm; p = 0.004). There was no difference in rotation between HV (0.82 ± 0.81°) and LV (0.61 ± 0.74°; p = 0.29). The LV-AF and LV-HF groups showed no statistical differences in MGW, ΔOSH, tilting or rotation (p > 0.05).SignificanceIrrespective of filler geometry and insertion technique, the use of high-viscosity composites for the adhesive cementation of modern all-ceramic partial crowns increases displacement, marginal misfit and occlusal surface height.     

Follow-up study to investigate symmetry and stability of cranioplasty in craniosynostosis – Introduction of new pathology-specific parameters and a comparison to the norm population

PurposeCranioplasty and modulation of frontoorbital advancement (FOA) in children with craniosynostosis aims to achieve an attractive aesthetic and functional rehabilitation of the forehead area, comparable to that in unaffected children. Based on a three-dimensional surface scan, a cephalometric data evaluation with new parameters for the quantification of physiological and pathological cranial morphologies, and objective evaluation of postoperative follow-up in comparison to an age-equivalent standard population, were performed.Materials and methodsIn a prospective study, 80 children were operated on with non-syndromic craniosynostosis (trigonocephalus, n = 30; plagiocephalus, n = 10; scaphocephalus, n = 38; brachycephalus, n = 2) and pre- and 3, 6, 12, 18 and 30 months postoperative three-dimensional surface scans were obtained (3DShape, Erlangen, Germany) and morphometrically measured (Onyx Ceph, Image Instruments, Chemnitz, Germany). In addition, 49 healthy children who were not operated on were measured at equivalent ages (n = 25 [6 months]; n = 20 [9 months]; n = 4 [12 months]).ResultsAll patient groups showed stable long-term results with regard to shaping of the forehead. Cranioplasty in patients with scaphocephalus resulted in a significant widening of the anterior (73.9 ± 3.5 mm; p < 0.001) and posterior (132.2 ± 5.2 mm; p < 0.001) cranial width, with no significant difference from the norm population 1 year after surgery (p = 0.6597). As parameters for the correction of trigonocephaly, the frontal angle showed significant improvement (145.9 ± 3.7°; p < 0.001). While the parietal angle 12 months after surgery showed similar values as the norm population, the frontal angle was about 10° smaller than in healthy children (p = 0.0055), despite a clinically inconspicuous physiognomy. As part of the correction of plagiocephaly, the patients tended to relapse in the postoperative course, although there was no statistically significant difference in the frontal angle compared to that in the norm population (153.3 ± 3.9°; p = 0.06). While 6 months after surgery all patients showed a normal cranial volume development compared to healthy children of the same age, the volumes of brachycephalic patients remained below the norm (1244.2 ± 153.2 cm³; p = 0.0244). Overall, the analysis of the norm population showed a growing dispersion of measurement values with increasing age, which was observed to be more concentrated in the operated cranial morphologies.ConclusionThe determination of new pathology-specific morphometric parameters on the three-dimensional surface scan enables an objective quantification of physiological and pathological cranial morphologies of children. A comparison of operated children with a healthy, age-appropriate comparison group showed that preoperative and statistically significant deviations of the new measuring parameters in long-term follow-up could be normalized through surgical intervention, although this does not apply without limitations to children with coronary suture synostosis.     

Mandibular resection and defect reconstruction guided by a contour registration-based augmented reality system: A preclinical trial

The aim of this study was to verify the feasibility and accuracy of a contour registration-based augmented reality (AR) system in jaw surgery.An AR system was developed to display the interaction between virtual planning and images of the surgical site in real time. Several trials were performed with the guidance of the AR system and the surgical guide. The postoperative cone beam CT (CBCT) data were matched with the preoperatively planned data to evaluate the accuracy of the system by comparing the deviations in distance and angle.All procedures were performed successfully. In nine model trials, distance and angular deviations for the mandible, reconstructed fibula, and fixation screws were 1.62 ± 0.38 mm, 1.86 ± 0.43 mm, 1.67 ± 0.70 mm, and 3.68 ± 0.71°, 5.48 ± 2.06°, 7.50 ± 1.39°, respectively. In twelve animal trials, results of the AR system were compared with the surgical guide. Distance deviations for the bilateral condylar outer poles were 0.93 ± 0.63 mm and 0.81 ± 0.30 mm, respectively (p = 0.68). Distance deviations for the bilateral mandibular posterior angles were 2.01 ± 2.49 mm and 2.89 ± 1.83 mm, respectively (p = 0.50). Distance and angular deviations for the mandible were 1.41 ± 0.61 mm, 1.21 ± 0.18 mm (p = 0.45), and 6.81 ± 2.21°, 6.11 ± 2.93° (p = 0.65), respectively. Distance and angular deviations for the reconstructed tibiofibular bones were 0.88 ± 0.22 mm, 0.84 ± 0.18 mm (p = 0.70), and 6.47 ± 3.03°, 6.90 ± 4.01° (p = 0.84), respectively.This study proposed a contour registration-based AR system to assist surgeons in intuitively observing the surgical plan intraoperatively. The trial results indicated that this system had similar accuracy to the surgical guide.     

Efficacy of inferior alveolar nerve block and intraligamentary anesthesia in the extraction of primary mandibular molars: A randomized controlled clinical trial

ObjectiveThe study aims to compare the effectiveness and quality of intraligamentary anesthesia (ILA) and inferior alveolar nerve block (IANB) for primary mandibular molar extraction.MethodsThis prospective, randomized clinical study included patients aged 5 to 13 years scheduled for primary mandibular molar extraction. A total of 208 participants were randomly allocated into two groups (n = 104 each group), IANB and ILA, who were administered 2% lignocaine with epinephrine 1:100,000. Patients rated their pain during injection and extraction (VAS pain score). Frankl’s behavior rating score, quality of anesthesia as perceived by clinician, and duration of procedure were recorded. Demographic and other variables were analysed using Pearson x² test, Pearson correlation coefficient, Fisher exact test, or an analysis of variance, as appropriate.ResultsIn patients who received IANB, the clinician reported a slightly better quality of anesthesia (p = 0.19) than those who received ILA (VAS score 1.3 ± 0.7 Vs 1.6 ± 0.4). Mean (±SD) score for pain during extraction were found be 1.7 (±0.6) for the IANB group and 1.8 (±0.5) for the ILA group. The clinician observed 46.2% of patients in the IANB group and 39.4% of patients in the ILA group had no discomfort during extraction. Frankl’s behavior score was negatively correlated with the quality of anesthesia and the time taken to complete the extraction (p = 0.017 and p = 0.053, respectively).ConclusionThe efficacy of conventional ILA was similar to IANB, and thus ILA might be a good alternative to the IANB while extracting primary mandibular molars.     

Accuracy of splint vs splintless technique for virtually planned orthognathic surgery: A voxel-based three-dimensional analysis

PurposeThis study compared two transferring methods for virtually planned orthognathic surgery — the CAD/CAM intermediate splint and the customized surgical guide with fixation plates.MethodsThis was a prospective clinical study in which participants were consecutively recruited and underwent bimaxillary orthognathic surgery. They were divided into two groups based on the transferring method used. The pre- and postoperative CBCTs were aligned using voxel-based landmark-free registration, and the discrepancies for selected points were compared with the planned displacement of the virtually planned surgery. The maxilla and mandible were analyzed separately, and translation and rotation movements were considered.ResultsA total of 16 patients, divided into two groups of eight patients each, were included in this study. The splintless group was significantly more accurate for the translation movement along the x-axes for points A (p = 0.008; mean absolute error 0.527 ± 0.387 for the splint group and 0.137 ± 0.067 for the splintless group) and Ans (p = 0.045; mean absolute error 0.535 ± 0.446 for the splint group and 0.156 ± 0.002 for the splintless group). For the mandible there was a significant difference in accuracy along the x-axes for points B (p = 0.049; mean absolute errors 1.728 ± 1.181 and 0.697 ± 0.519 for the splint and splintless groups, respectively), LL3 (p = 0.049; mean absolute error 1.629 ± 0.912 and 0.851 ± 0.797 for the splint and splintless groups, respectively), LR3 (p = 0.049; mean absolute error 1.711 ± 0.906 and 0.844 ± 0.780 for the splint and splintless groups, respectively), with the splintless group being more accurate. For the rotation the splintless group was significantly more accurate along the y-axes (p = 0.04; mean absolute error 1.62 ± 0.78 and 0.49 ± 0.31 for the splint and splintless groups, respectively) and z-axes (p = 0.04; mean absolute error 0.63 ± 0.45 and 0.17 ± 0.05 for the splint and splintless groups, respectively) for the maxilla, while no significant difference was found for the mandible.ConclusionsOverall, the customized fixation plate system is more accurate than the intermediate CAD/CAM splint for transferring the virtual plan into the operation room.     

Accuracy of maxillary repositioning surgery using CAD/CAM customized surgical guides and fixation plates

The advent of three-dimensional imaging and computer-aided surgical simulation (CASS) have brought about a paradigm shift in surgical planning. The aim of this study was to assess the accuracy of maxillary repositioning surgery using computer-aided design and manufacturing (CAD/CAM) customized titanium surgical guides and fixation plates. Thirty consecutive adult patients, 13 male and 17 female, with a mean age of 29.2 years and 25.5 years, respectively, requiring Le Fort I maxillary osteotomy, with or without simultaneous mandibular surgery, were evaluated retrospectively. All orthognathic surgeries were performed by one experienced surgeon. The pre-surgical and post-surgical volumetric imaging were superimposed to assess the linear and angular differences between the planned and actual positions of the maxilla following surgery. With the use of the CAD/CAM titanium surgical guides and fixation plates, all surgical movements were within 2 mm and 4° of the planned movements, which is considered clinically insignificant. The overall root mean square error between the planned and actual surgical movements was 0.38 mm in the transverse dimension, 0.64 mm in the anteroposterior dimension, and 0.55 mm in the vertical dimension. In regard to the centroid of the maxilla, the absolute angular difference of the maxillary centroid was 1.06° in pitch, 0.47° in roll, and 0.49° in yaw. Maxillary repositioning surgery can be performed with high accuracy using CAD/CAM titanium surgical guides and fixation plates.     

Evaluation of border movement of the mandible before and after orthognathic surgery using a kinesiograph

PurposeThe purpose of this study was to examine the changes in the mandibular border movement between class II and class III jaw deformity patients before and after orthognathic surgery, by using the same device.Subjectsand Methods: Eighty one patients (28 in class II and 53 in class III) who underwent sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy using absorbable plate fixation and 27 controls with normal occlusion were enrolled. Mandibular border movement (observed using a kinesiograph) was recorded with a mandibular movement measure system (K7) before surgery, and at 6 months and 1 year after surgery. Time-course changes of 5 components of the mandibular border movement (MVO: Maximum vertical opening, CO to MAP: Maximum antero-posterior movement from centric occlusion, MLDL: maximum lateral deviation left, MLDR: maximum lateral deviation right, CO to MO: centric occlusion to maximum opening) were compared between classes II, III and controls statistically. The relationship between lateral cephalometric measurements and the components of mandibular border movement was also examined.ResultsThere was a significant difference in CO to MAP (P = 0.0025) and CO to MO (P < 0.0001) between class II and class III in the time-course change.In class III, mean and standard deviation of MVO were 44.5 ± 6.7 mm before surgery and 39.8 ± 6.8 mm after 1 year. Mean and standard deviation of CO to MAP were 25.2 ± 6.8 mm before surgery and 21.5 ± 7.9 mm after 1 year. Mean and standard deviation of CO to MO were 53.4 ± 9.0 mm before surgery and 47.3 ± 8.4 mm after 1 year.In class II, mean and standard deviation of MVO were 38.8 ± 5.8 mm before surgery and 36.2 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MAP were 18.0 ± 6.3 mm before surgery and 17.8 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MO were 43.1 ± 7.5 mm before surgery and 39.6 ± 10.5 mm after 1 year.In MVO, CO to MAP and CO to MO, the values after 1 year did not significantly reach the pre-operative values in class III (P = 0.0001, P = 0.0007 and P < 0.0001), although there was no significant difference between pre-operation and after 1 year in class II.In CO to MO, class II (mean and standard deviation 39.6 ± 10.5 mm) and class III (mean and standard deviation 47.3 ± 8.4 mm) still remained smaller values than control (mean and standard deviation 52.7 ± 9.2 mm) after 1 year (P < 0.0001 and P = 0.0095).ConclusionThis study suggests that bi-maxillary surgery can have more influence on the reduction in the range of mandibular border movement including vertical or antero-posterior motion than lateral deviation motion, in both groups. The difference in the time-course change in the mandibular border movement between the groups might depend more on the mandibular length than on the movement direction of the mandible by surgery such as advancement or setback.     

The effects of local and intraperitoneal zinc treatments on maxillofacial fracture healing in rabbits

ObjectiveThis study aimed to determine whether administration of topical and intraperitoneal zinc for maxillofacial fractures has any impact on the bone healing process.Material and methodThirty-two New Zealand rabbits were randomly assigned to four groups of eight each. The first group was the control group; fracture lines were fixed using titanium microplates and no medication was administered. The second group received fixations using zinc-coated titanium microplates. A single dose of 3 mg/kg zinc was administered intraperitoneally to the third group following fixations with titanium microplates. A single dose of 3 mg/kg zinc was administered intraperitoneally to the fourth group following fixations with zinc-coated titanium microplates. Zinc coating on to the titanium microplates was achieved using the physical vapor deposition technique. A fracture line was created in the nasal bones of all subjects and fixed with five-hole flat microplates and three 5-mm micro screws. All work groups were sacrificed at the end of the sixth week.ResultsHistological examination showed that the number of osteoblasts were significantly higher in zinc-coated group (Group 2) than zinc uncoated, control group (Group 1), (415.6 ± 46.7 vs 366.3 ± 11.8) (p < 0.001). It was observed that intraperitoneal zinc treatment alone (Group 3) did not significantly increase in the osteoblast count compared to zinc un-coated group (Group 1), (390.6 ± 83.2 vs 366.3 ± 11.8), (p = 0.341). The immunoreactivity scores for IGF-1 were significantly higher in the zinc-coated group compared to control group (Group 2 vs 1), (9.3 ± 2.8 vs 3.7 ± 1.9) (p < 0.05). It was observed that intraperitoneal zinc treatment did not cause a significant difference in the aspect of IGF-1 for zinc-coated groups (Group 2 vs 4) (9.3 ± 2.8 vs 9.6 ± 2.2) (p = 0.791). The difference in the immunoreactivity score among whole groups for TGF-β was not statistically significant (Group 1 vs 2, 3.2 ± 1.7 vs 4.4 ± 2.3, p = 0.256; Group 1 vs 3, 3.2 ± 1.7 vs 3.8 ± 2.8, p = 0.524; Group 1 vs 4, 3.2 ± 1.7 vs 2.8 ± 1.3, p = 0.717; Group 2 vs 3, 4.4 ± 2.3, vs 3.8 ± 2.8, p = 0.610; Group 2 vs 4, 4.4 ± 2.3, vs 2.8 ± 1.3, p = 0.124; Group 3 vs 4, 3.8 ± 2.8, vs 2.8 ± 1.3, p = 0.311).ConclusionThe local use of titanium microplates coated with zinc by PVD technique was found effective for fracture healing. Zinc coating of titanium microplates used in fracture treatment can accelerate fracture healing. It may be concluded that clinical studies should be performed now in order to explore if comparable results can be achieved in humans.     

2D/3D accuracies of implant position after guided surgery using different surgical protocols: A retrospective study

PurposeTo compare the 2D and 3D positional accuracy of four guided surgical protocols using an analysis of linear and angular deviations.MethodsDICOM and .STLs files obtained from a CBCT and a digital impression were superimposed with software to plan implant position. Fifty-six patients were subdivided into 4 groups: FGA group (template support [Ts]: teeth [T]; bed preparation [Bp]: fully guided [FG]; implant insertion [Ii]: 3D template [3Dt]; device [D]: manual adapter [MA], FGM group (Ts: T; Bp: FG; Ii: 3Dt; D: fully guided mounter [FGM]), PG group (Ts: T; Bp: FG; Ii: manual; D: none) and MS group (Ts: mucosa; Bp: FG; Ii: 3Dt; D: FGM). The position of 120 implants was assessed by superimposing the planned and final position recorded with a digital impression.ResultsIn FGA group, 3D deviations were 0.92 ± 0.52 mm at the implant head and 1.14 ± 0.54 mm at the apex, and the angular deviation (ang. dev.) was 2.45 ± 1.24°. In FGM group, were 0.911 ± 0.44 mm (head) and 1.11 ± 0.54 mm (apex), and the ang. dev. was 2.73 ± 1.96°. In PG group, were 0.95 ± 0.47 mm (head) and 1.17 ± 0.488 mm (apex), and the ang. dev. was 3.71 ± 1.67°. In MS group, were 1.15 ± 0.45 mm (head) and 1.42 ± 0.45 mm (apex), and the ang. dev. was 4.19 ± 2.62°. Ang. dev. of MS group was different from the other groups (P < 0.05).ConclusionsGuided surgery showed a sufficient accuracy.     

Changes in condylar position after orthognathic surgery and its correlation with temporomandibular symptoms (TMD)- a prospective study

The aim of the study was to assess the changes in the condylar position after orthognathic surgery (OGS) and its effect on temporomandibular disorders (TMD). A total of 37 dentofacial deformity patients included in the study who had undergone OGS were divided into three groups: Group I, Le Fort I maxillary advancement; Group II, bilateral sagittal split osteotomy (BSSO) mandibular advancement ± Le Fort I; and Group III, BSSO mandibular setback ± Le Fort I. Patients were evaluated clinically using Diagnostic Criteria for TMD and by radiography preoperatively and 6 months postoperatively. The positional changes in condyle were correlated with signs and symptoms of TMD. A total of 37 patients in three groups (Group I, 8 patients; Group II, 10 patients; and Group III, 19 patients) were evaluated. Overall, condyles had anterio-medio-inferior movement with 7 of 8 patients in Group I, 6 of 10 patients in Group II and 13 of 19 patients in Group III having ≤2 mm displacement. In angular changes, inward-anterio-medial movement was observed with 6 of 8 patients in Group I; about 5 of 10 patients, and 10 of 19 patients in Group II and III respectively had ≤5° change. Intragroup and intergroup comparisons showed insignificant changes in TMD and linear/angular movement (p ≥ 0.05). Pearson correlation coefficient was found to be nonsignificant on the radiographic and clinical comparison (p ≥ 0.05). Intrarater reliability (Kappa value) was found to be 0.83, confirming the results. Within the limitations of the study it seems that there are minimal linear and angular changes in condyle after orthognathic surgery that were not responsible for the development of temporomandibular disorders in the postoperative course.     

Posterior bending osteotomy: An effective measure to secure facial symmetry in orthognathic surgery

This study aimed to compare the effectiveness of posterior bending osteotomy and grinding techniques for orthognathic surgery in patients with facial asymmetry. Patients who had undergone Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, and who presented with a menton shift and setback difference exceeding 4 mm, were enrolled. Cone-beam computed tomography was performed before surgery (T0), immediately after surgery (T1), and 6 months after surgery (T2). Overall, 38 patients were included and divided into posterior bending osteotomy (n = 23) and grinding (n = 15) groups.Significant differences were observed between the posterior bending osteotomy and grinding groups on the treated side. In the grinding group, the gonion on the treated side was displaced slightly outward, resulting in a significant difference between both sides (non-treated side: 50.52 ± 4.20 [T0] and 48.67 ± 4.37 [T2]; treated side: 50.88 ± 4.55 [T0] and 51.00 ± 3.95 [T2]; p = 0.038). In the posterior bending osteotomy group, bilateral inward movements of the gonion were observed, and the distance from the midsagittal plane to the gonion did not differ significantly between the sides (non-treated side: 46.74 ± 4.41 [T0] and 45.54 ± 3.95 [T2]; treated side: 47.43 ± 4.93 [T0] and 45.18 ± 3.52 [T2]; p = 0.224). The yawing movement of the proximal segment was greater in the grinding group than in the posterior bending osteotomy group (non-treated side: p = 0.839; treated side: p = 0.025).Posterior bending osteotomy is recommended over the grinding method for patients with severe facial asymmetry, in order to ensure a symmetric and esthetic facial profile by allowing passive adaptation between the mandibular segments.     

Intraoral versus transcervical approaches in mandibular reconstruction with free flaps: A retrospective study

This study aims to investigate the clinical and functional differences between intraoral and transcervical approaches for segmental mandible resection and reconstruction with free flaps. Patients diagnosed as benign and low-grade mandibular malignant tumors without neck dissections were retrospectively reviewed and divided into intraoral and transcervical groups. Patients of intraoral group underwent intraoral mandibulectomy and vascular anastomosis was performed through a 2-cm submandibular incision, while traditional submandibular approach was used in transcervical group. Clinical characteristics of two groups were assessed including body mass index (BMI), defect types and number of fibular segments, as well as perioperative variables such as operation time, blood loss, drainage volume. The score of appearance, swallowing and speech using the University of Washington Quality of Life Questionnaire (UW-QOL) was recorded and analyzed 6-month postoperatively.A total of 14 patients in intraoral group and 21 patients in transcervical group was collected, respectively. In intraoral group, intraoperative blood loss and postoperative drainage volume were significantly reduced in comparison with transcervical group (p = 0.0146, p = 0.0017; respectively). The score of appearance was 87.50 ± 12.97 in intraoral group, which was significantly higher than 64.29 ± 12.68 in transcervical group (p < 0.0001). Similar results were found in patients of subtype Class II mandibular defect between two groups. However, patients of intraoral group had a significant increase in operative time and a comparable amount of intraoperative blood loss (p = 0.0472, p = 0.1434; respectively).Within the limitations of the study it seems that an intraoral approach combined with a 2-cm submandibular incision should be preferred over a transcervical approach for segmental mandibulectomy and free flap reconstruction whenever appropriate.     

The effect of arthroscopic disc repositioning on facial growth in juvenile patients with unilateral anterior disc displacement

ObjectiveTo investigate the effect of arthroscopic disc repositioning on condylar development and mandibular asymmetry in juvenile patients with unilateral temporomandibular joint (TMJ) anterior disc displacement (ADD).Patients and methodsA retrospective cohort study was conducted on unilateral juvenile anterior disc displacement (UJADD) patients of 10–20 years of age treated in Shanghai Ninth People's Hospital from 2010 to 2017. The primary predictor was TMJ arthroscopic disc repositioning surgery, according to which patients were divided into a surgery group and a control group. Initial and re-examined (with at least 6-month interval) magnetic resonance imaging (MRI) and posteroanterior cephalometric radiographs (PA) were collected. The condylar heights on both sides of the TMJ were measured by MRI and the difference between them was calculated. Menton (Me) deviation was measured based on PA. Changes in condylar height difference and Me deviation were compared between the two groups.ResultsA total of 108 UJADD patients were collected in this study, including 55 patients in the surgery group and 53 patients in the control group. There were no significant differences in age, sex and follow-up time between the two groups. The condylar height difference was (−0.61 ± 2.02) mm in surgery group and (1.68 ± 1.73) mm in control group (P < 0.0001); while the Me deviation was (−1.00 ± 1.15) mm in surgery group and (1.81 ± 1.96) mm in control group (P < 0.0001), indicating that TMJ arthroscopic disc repositioning surgery could significantly improve condylar height difference and Me deviation.ConclusionsUJADD should be treated as early as possible, especially in juvenile patients, in order to improve condylar development and avoid jaw deformities.     

Histological evaluation of the healing process of autografted mandibular bone defects in rats under treatment with zoledronate

ObjectiveThis study aims to evaluate the healing process of autografted mandibular bone defects in rats treated with zoledronate (ZOL).Subjects and methodsA total of 180 Wistar rats were divided into four groups: group L received intravenous infusion of two doses of 0.06 mg/kg ZOL, nine weeks apart; group H received 0.06 mg/kg ZOL, while groups C and NC received normal saline at three-week intervals for nine weeks. Three weeks following the last infusion, a unilateral mandibular bone defect (5 mm) was created. Except in the NC group, all defects were repaired with autologous iliac bone graft. Fifteen animals from each group were sacrificed on postoperative Day 20, Day 40, and Day 60. Graft healing was scored using a histological grading system (ranging from 1 to 6).ResultsHistological evaluations performed on postoperative Day 60 showed that the mandibular defects were mainly repaired with fibrous tissue in the NC and H groups (93.00% ± 7.51% and 82.67% ± 13.08%, respectively) and with bone in the C and L groups (75.33% ± 14.20% and 92.67% ± 8.84%, respectively). The percentage of fibrous tissue and bone as well as the healing score of the NC and H groups were significantly different (P = 0.001) from those of the C and L groups. However, these were not different between neither the NC and H groups nor the C and L groups.ConclusionBased on the results of the present study the hypothesis can be established that there also might be a dose-dependent effect of ZOL on the healing of bone grafts in humans. This hypothesis has to be verified or rejected in clinical trials.     

Single stage surgery for contouring the prominent mandibular angle with a broad chin deformity: En-bloc Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG)

BackgroundVarious surgical options are reported to address the Asian 'squared face', characterized by a prominent mandibular angle (PMA) associated with an oversized chin deformity; but shortcomings lie in the requirement of multi-stage procedures with the risk of further revision surgery. We have developed a single-stage “Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG)” surgical technique to shorten the period of the surgical treatment and minimize the inherent surgical risks in the multi-staged procedures.MethodsA retrospective study involving patients (n = 36) presented with prominent mandibular angle and an oversized chin who underwent the operation described from 2010 to 2012 with at least 12 months of follow-up. The surgical and aesthetic outcomes were evaluated through clinical assessment, photography, imaging analysis including preoperative and post-operative patient satisfaction rates.ResultsAll the patients were satisfied with the improvement in their appearance following surgery; specifically the 'smoothness' of the mandibular inferior border with no 'second mandibular angle'. The width of the mandible was reduced with G–G distance reduced from 119.9 mm ± 3.9–109.7 mm ± 3.5 (p < 0.05). A significant preoperative and post-operative gonial angle (G-A) was found at the left (110.7° ± 9.6 vs 139.9° ± 11.5, p < 0.05) and right side of mandible (111.3° ± 10.7 vs 140.7° ± 11.8, p < 0.05). There was no iatrogenic inferior alveolar nerve or mental nerve injury and a stable aesthetic outcome beyond the first year.ConclusionWe demonstrated favourable surgical and aesthetic outcomes with our single-stage en-bloc curved osteotomy surgical technique to reshape the prominent mandibular angle with a broad chin deformity with no increased in surgical risks but a high satisfaction rate and stable outcomes.     

Retrospective study on the pharyngeal airspace in the lateral cephalogram - A mathematical model to predict changes due to bimaxillary orthognathic surgery

The aim of this study was the development of a statistical model for reliable prediction of Posterior Airway Space (PAS) changes in lateral cephalograms (LCR) of patients after bimaxillary orthognathic surgery. The LCRs of patients who underwent bimaxillary orthognathic surgery were retrospectively analyzed. The anteroposterior dimension of the PAS was measured at three levels in the pre-operative and postoperative LCR: On the nasopharyngeal (SPAS), oropharyngeal (MAS), and hypopharyngeal level (IAS). The data of 139 patients were collected. The following changes of the PAS were measured: in class II patients SPAS: 0.291 mm (SD = 2.570 mm); MAS: 2.444 mm (SD = 2.986 mm); IAS: 0.750 mm (SD = 3.017 mm); in class III patients SPAS: 1.377 mm (SD 3.212 mm); MAS: 0.962 (SD: = 3.135 mm); IAS: 0.370 mm (SD = 3.468 mm). Linear regression analysis showed for class II patients, a significant influence of mandibular movement on MAS (p = 0.049) and a significant effect of maxillary and mandibular movements on SPAS (p = 0.001) and MAS (p = 0.022) in class III patients. The other jaw displacements had no significant impact on the investigated PAS levels. While the presented method does not permit exact prediction of the dimension of the PAS, it is still an easily accessible method of orientation for the surgeon. The surgeon can initiate three-dimensional examinations to provide exact three-dimensional prediction based on this calculation.     

Accuracy of virtual surgical planning in bimaxillary orthognathic surgery with mandible first sequence: A retrospective study

The aim of this study was to verify treatment accuracy using virtual surgical planning (VSP) with a mandible-first sequence and strict surgical protocol to determine what surgical and methodological factors might influence outcomes.VSP transfer accuracy was evaluated retrospectively through a modified method involving voxel-based superimposition in patients who had undergone bimaxillary surgery with a mandible-first sequence to correct dentoskeletal deformities. Data analysis showed that the movements planned and those executed were substantially equivalent (p < 0.01), with the exception of mandibular and maxillary sagittal movements that were 0.72 ± 0.90 mm and 1.41 ± 1.04 mm smaller, respectively, than planned.This study showed that a mandible-first sequence is accurate for transferring virtual surgical planning intraoperatively. There are several factors involved in the proper transfer of virtual planning beyond the software, such as surgical technique and sequencing. Inaccurate sagittal movements and maxillary repositioning seem to depend mainly on surgical factors.