Use of CAD-CAM technology to improve orthognathic surgery outcomes in patients with severe obstructive sleep apnoea syndrome

IntroductionAlthough multilevel surgery is the mainstay treatment for severe obstructive sleep apnoea syndrome (OSAS), bi-maxillary surgery (maxillomandibular advancement [MMA]) is the most efficacious single procedure for the expansion of the whole pharyngeal airway. MMA is an alternative to the gold standard of continuous positive airway pressure and is equivalent to tracheotomy.Patients and methodComputer-aided design/computer-aided manufacturing (CAD-CAM) technology was used to virtually assess the degree of mandibular and/or maxillary advancement and rotation required to obtain adequate posterior airway space (PAS) in eight patients (seven males, one female). The mean age of the patients was 45.5 years (range, 27–51 years), and the average body mass index was 28.9 kg/m² (range, 21.9–31.8 kg/m²).ResultsThe study group showed significant mandibular advancement, widening of the PAS, and reduction of the apnoea hypopnea index (p < 0.0001, p < 0.0001, and p < 0.0002, respectively). Moreover, patient satisfaction scores regarding postoperative facial profile changes showed excellent compliance.ConclusionThis study demonstrated that bi-maxillary surgery is an efficient single surgical procedure in patients with multilevel OSAS. CAD-CAM technology aided surgeons in performing this operation precisely and enabled patients to expect specific facial profiles.     

Evaluation of post-surgical stability in skeletal class II patients with idiopathic condylar resorption treated with functional splint therapy

PurposeTo assess postsurgical stability of mandibular advancement combined with orthodontic treatment, following functional splint therapy, in patients with idiopathic condylar resorption (ICR).Patients and methodsSixteen patients who were treated with functional splint therapy followed by orthognathic surgery combined with orthodontic treatment between 2010 and 2017 were included in this retrospective study. The primary outcome variable was skeletal stability, measured on the y-axis to point B (y-axis–B). Cephalometric analysis, including measurement of temporomandibular joint spaces, was carried out on serial magnetic resonance images (MRI) prior to orthognathic surgery (T0), immediately after surgery (T1), and after at least 1 year of follow-up (T2). The differences in the data between time points were compared using statistical analyses.ResultsAll patients obtained an esthetic facial profile after orthognathic surgery, with normal occlusion as well as normal protrusive and laterotrusive excursion after treatment. Mean advancement of the mandible immediately following surgery (y-axis–B, T1 − T0) was 7.28 ± 5.79 mm. This was the only skeletal measurement that showed a sagittal positional change of the mandible. Mean backward movement (T2 − T1) was −1.04 ± 2.35 mm (p₂ = 0.116). Thirteen out of 16 patients experienced no postsurgical relapse or less than 2 mm of mandibular backward movement (81.25%), while two out of 16 patients showed more than 2 mm of mandibular backward movement (12.5%).ConclusionsPatients who underwent mandibular advancement combined with orthodontic treatment, following functional splint therapy, exhibited a stable mandibular position at the 1-year follow-up. This study indicated that functional splint therapy prior to orthognathic surgery for mandibular advancement may be a good adjuvant treatment for ICR patients.     

Accuracy of patient-specific implants and additive-manufactured surgical splints in orthognathic surgery — A three-dimensional retrospective study

IntroductionBecause of the many limitations of conventional surgery planning for the treatment of orthognathic deformities, as well as advancements in computer-assisted planning, there is an urgent need for technical devices that transfer the surgical plan into the operating theatre. In this regard, additive-manufactured, patient-specific implants (PSI) and additive-manufactured interocclusal splints represent promising approaches. The aim of this retrospective study was to compare the accuracy of these two devices, with regard to preoperative virtual treatment planning for maxillary Le-Fort I advancement surgery using IPS CaseDesigner^®, and based on a new analysis method without the use of landmarks.Materials and methodsA retrospective evaluation of 18 class III patients (n(PSI) = 9; n(splint) = 9), who had undergone virtually planned orthognathic surgery (including maxillary Le Fort I advancement), was performed. The preoperative treatment plan and the postoperative outcome were combined to calculate the translational and rotational discrepancies between the 3D planning and the actual surgical outcome.ResultsFor the PSI and splint groups the accuracy of left/right positioning was 0.51 mm ± 0.48 and 1.11 mm ± 1.32 respectively. The accuracy of anterior/posterior positioning was 0.39 mm ± 0.26 and 1.42 mm ± 0.87, and that of up/down-positioning was 0.44 mm ± 0.31 and 0.62 mm ± 0.47. The rotational discrepancies were less than 2° in both groups. Conclusion: The findings demonstrate that both PSI and splint approaches can accurately transfer the virtual planning into the operating theatre. However, PSIs show an overall higher accuracy, especially for anterior/posterior translational movement (p < 0.002).     

Excessive ossification of the bandeau in Crouzon and Apert syndromes

BackgroundThe study aimed at assessing the variations in thickness of the supra-orbital bar in Crouzon (CS) and Apert syndromes (AS) before and after fronto-facial monobloc advancement (FFMBA) using CT-scan data.MethodsAll CS or AS patients who underwent FFMBA between 2008 and 2018 with available clinical and CT-scan data were included. Frontal bone thickness was assessed at five locations of the supra-orbital bar using the Half-Maximum-Height protocol and plotted over the bone surface.ResultsWe included 210 CT-scans from 25 CS to 10 AS patients and 25 controls. Before FFMBA, CS children only had a significantly thicker frontal bone (+0.772 mm ± 0.312, p = 0.017). After FFMBA, a significant increase in frontal bone thickness was reported for CS at 3 months (+0.637 mm ± 0.141, p < 0.001), 6 months (+0.910 mm ± 0.120, p < 0.001) and 12 months (+1.099 mm ± 0.124, p < 0.001) post-operatively as well as in AS at 1 month (+2.069 mm ± 0.441, p < 0.001), 6 months (+1.247 mm ± 0.406, p = 0.003) and 12 months (+2.360 mm ± 0.284, p < 0.001) post-operatively. For both syndromes, age at FFMBA and specific FGFR2 mutations significantly influenced post-operative frontal bone thickness.ConclusionsCraniofacial surgeons should be aware of the potential need for secondary surgery of the supra-orbital after FFMBA in CS and AS. Furthermore, a thicker supra-orbital bar is part of the CS phenotype, illustrating the role of FGFR2 in craniofacial growth.     

The inverted-L ramus osteotomy versus sagittal split ramus osteotomy in maxillomandibular advancement for the treatment of obstructive sleep apnea patients: A retrospective study

This study aimed to compare the effectiveness and feasibility of inverted-L osteotomy (ILO) and sagittal split ramus osteotomy (SSRO) on obstructive sleep apnea (OSA) treatment. According to different surgery procedures, 28 OSA patients who underwent maxillomandibular advancement (MMA) were divided into 2 groups (group A: ILO, n = 9; group B: SSRO, n = 19). Polysomnography (PSG) and Epworth sleepiness scale (ESS) on T0, T1and T2 were used to evaluate the effectiveness of OSA treatments. Patients’ airway structures and facial appearances were also evaluated. From T0 to T1, the mean apnea-hypopnea index (AHI,/per hour) dropped from 69.2 ± 8.4 to11.2 ± 2.4 (P < 0.01) in group A and from 54.6 ± 14.6 to 9.4 ± 5.4 (P < 0.01) in group B; LSpO2 (lowest pulse oxygen saturation, %) increased from 66.5 ± 7.7% to 88.2 ± 4.6 (P < 0.01) and from 76.6 ± 10.7%to 89.4 ± 2.4% (P < 0.01) while the mean ESS score decreased by 51% in group A and 44% in group B. Most patients (group A: 88.9%; group B: 84.3%) were satisfied with their postoperative appearance. Mild relapse was observed in both groups on T2. This study concluded that MMA containing ILO and MMA containing SSRO are both feasible and effective for selected OSA patients.     

Does the Kushida morphometric model predict outcomes following maxillomandibular advancement surgery for obstructive sleep apnoea?

ObjectiveThe primary aim of this study was to explore the predictive potential of the preoperative Kushida index score and subsequent outcome following maxillomandibular advancement surgery (MMA). Secondarily we looked at how well the Kushida values of our OSA patients matched the morphometric models diagnostic thresholds.MethodsWe performed a retrospective analysis of patients who underwent MMA for OSA at our institution. Kushida morphometric scores were calculated using the described formula: P + (Mx − Mn) + 3 × OJ + 3 × [Max (BMI − 25)] × (NC ÷ BMI). Regression analysis was performed to explore the possible association between Kushida index score and outcome variables of postoperative apnoea/hypopnea indices (AHI) and Epworth Sleepiness Scores (ESS).ResultsWe identified 28 patients with complete data available for analysis. The mean age was 45 years (SD 6) with mean BMI of 28 (SD 3). All, but one patient underwent bi-maxillary procedure with or without genioplasty, with a mean advancement of 8.5 mm (SD 2). The mean Kushida index score in our sample was 79 (SD 14). 89% of patients had postoperative AHI <15 in keeping with surgical success. We found no statistically significant relationship with Kushida morphometric model variables and overall score with either of our outcome variables.ConclusionThe mean Kushida index score in our patients was in the range consistent with the morphometric models diagnostic cut-off for OSA. Kushida's morphometric model does not appear to be a good predictor of postoperative success in individuals following MMA. The morphometric model represents a clinical adjunct in the initial diagnostic work-up of OSA patients referred for surgery.     

Effectiveness of maxillo-mandibular advancement in obstructive sleep apnea patients with and without skeletal anomalies

This study evaluates the effectiveness of maxillo-mandibular advancement (MMA) in patients with obstructive sleep apnea syndrome (OSAS), even those without skeletal anomalies, indicating the possibility of extending this procedure to more patients. Two groups with different skeletal patterns were studied pre- and post-surgery. Group 1 (11 patients) had severe or moderate OSAS and maxillo-mandibular hypoplasia and/or mandibular deformities (SNA angle 78° or less or SNA angle > 78° but with SNB < 65° and severe skeletal class II malocclusion). Group 2 (11 patients) had severe or moderate OSAS without maxillo-mandibular hypoplasia or deformity (SNA angle > 80°, dental class I occlusion). Analysis comprised: apnea hypopnea index (AHI), posterior airway space (PAS), SNA and SNB angles, Epworth sleepiness scale (ESS), body mass index (BMI), and a subjective standardized questionnaire about aesthetic appearance. All patients had increased PAS width and complete remission of objective and subjective OSAS symptoms evaluated by AHI and ESS. Results in both groups are comparable. Data were analysed using t-test; p < 0.005 was statistically significant. All patients were satisfied with the functional and aesthetic results. MMA is effective in patients with severe or moderate OSAS, even in those without skeletal and/or occlusal anomalies and can be considered in more patients.     

The effect of aging on the wear performance of monolithic zirconia

ObjectivesInvestigate the effect of aging on the wear behavior of glazed vs polished monolithic zirconia and to establish if glazing provides protection against low temperature degradation.Methods40 1-mm-diameter spheres made from four differently treated monolithic zirconia (VITA YZ® HT); polished, polished-aged, glazed and glazed-aged (n = 10), were tested in a wear testing machine (UFW200) against bovine enamel in artificial saliva as per the following settings (ISO20808:2016): ball-on-disc configuration, 5 N vertical load, 0.1 m/s sliding speed, 400 m sliding distance and 37 °C temperature. Vertical substance loss (mm) wear of zirconia and enamel specimens was measured. Data were statistically analyzed with Kruskal-Wallis one-way ANOVA test (α > 0.05).ResultsGlazed-aged zirconia specimens resulted in the greatest amount of enamel wear (0.823 mm ± 0.157) followed by glazed (0.729 mm ± 0.289), polished-aged (0.377 mm ± 0.201) then polished (0.247 mm ± 0.125). In the groups with the same surface finish, aging showed no statistical difference in wear (P > 0.008). Glazing resulted in a higher enamel wear compared with polishing that was statistically significant (P < 0.008) except when the polished specimens were aged and the glazed specimens were not aged.SignificanceAging increases abrasiveness of monolithic zirconia regardless of the type of surface finish. The effect of aging is “latent” and only revealed under mechanical loading during wear simulation which increases surface roughness and wear by adversely affecting zirconia’s mechanical properties, making it less capable to maintain its initial surface smoothness. The glaze layer may protect zirconia from LTD, however, it is susceptible to aging which further increases its abrasiveness.     

Does platelet-rich fibrin increase stability of the maxilla following Le Fort I osteotomy? A single-blind clinical trial study

This single-blind clinical trial study aimed to assess the efficacy of platelet-rich fibrin (PRF) in increasing stability following Le Fort I osteotomy for maxillary advancement. Patients who underwent Le Fort I osteotomy for maxillary advancement were assigned randomly into two groups: in group 1 (the study group, n = 22) PRF was placed in the osteotomy sites following fixation, while no PRF was used in group 2 (the control group, n = 22). Lateral cephalograms obtained preoperatively (T0), immediately after surgery (T1), and 1 year after surgery (T2) were compared between the two groups, and the amount of relapse was determined. The amount of maxillary change (relapse) at the A point in relation to the x-axis was 0.45 ± 0.67 mm in group 1 and 1.86 ± 0.56 mm in group 2. There was a significant difference in mean relapse in relation to the x-axis between the two groups 12 months after osteotomy (p < 0.001). The mean maxillary change (relapse) in relation to the y-axis was 0.77 ± 1.15 mm in group 1 and 2.25 ± 1.22 mm in group 2. Analysis of the data demonstrated a significant difference in mean relapse in relation to the y-axis between the two groups (p < 0.001). PRF may enhance the stability of the maxilla following Le Fort I osteotomy. Based on the results of this study the administration of PRF should be considered whenever possible.     

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.     

Mandibular effects of maxillary distraction osteogenesis in cleft lip and palate

Maxillary distraction osteogenesis (DO) is a reliable treatment for severe maxillary deficiency in cleft lip and palate (CLP). The objective was to analyze its long-term effects on the mandible. A retrospective study of 24 CLP treated with maxillary DO using the Polley and Figueroa technique was done; patients were followed for more than 4 years. Preoperative (T0), 6–12 months postoperative (T1), and ≥4 years postoperative (T2) cephalometric radiographs were evaluated. A classical cephalometric analysis was used to assess treatment stability, and a Procrustes superimposition method was used to assess local changes in the shape of the mandible. The mean age of patients at T0 was 15.4 ± 4.1 years. SNA increased at T1 and T2 (P < 0.001), with no significant relapse between T1 and T2, indicating stability at 1 year after treatment (T0 = 72.4 ± 5.3°; T1 = 81.3 ± 6.2°; T2 = 79.9 ± 6.1°). SNB, facial angle, gonial angle, and symphyseal angle remained stable. Long-term analysis of the mandible demonstrated a minimal counter-clockwise rotation of the body (mandibular plane = −0.2 ± 3.2°) and ramus (−0.6 ± 4.3°). Maxillary DO in CLP had no significant effect on the shape or rotation of the mandible. The maxillary advancement remained stable after 1 year.     

Pharyngeal airway space changes after maxillomandibular advancement: a five-year retrospective study

The aim of this study was to compare the alterations in three regions of the airway—nasopharynx, oropharynx, and hypopharynx—in relation to the area of the midsagittal plane, volume, and minimal axial area after maxillomandibular advancement (MMA) surgery. Thirty patients who had undergone MMA surgery were evaluated at four time points: preoperative (T0), immediately postoperative (T1), 1 year postoperative (T2), and ≥5 years postoperative (T3). All measurements were performed using computed tomography, analyzed in Dolphin Imaging 11.0 Premium 3D software. The area in the midsagittal plane presented a mean increase of 22.0% between T0 and T3 (P < 0.001), with the highest increase in the oropharynx (24.1%, P < 0.001). The total volumetric increase at T3 was 16.7% (P < 0.001), with the highest increase in the nasopharynx (15.7%; P < 0.001). The lowest minimal axial area was found for the oropharynx at all time points, and the highest increase in minimal axial area was found for the nasopharynx (114.9%; P < 0.001). MMA surgery showed the highest increase in upper posterior airway between T0 and T1, and this was followed by a progressive reduction until T3, but with a statistically significant increase at T3 compared with T0 in all cases.     

Three-dimensional development of the palate in bilateral orofacial cleft newborns 1 year after early neonatal cheiloplasty: Classic and geometric morphometric evaluation

ObjectivesThe aim of this study was to assess palatal growth in newborns with complete bilateral cleft lip and palate (cBCLP) and bilateral cleft lip and palate with tissue bridges (BCLP + B) 1 year after early neonatal cheiloplasty (ENC).Material and methodsThe methodology was based on classic and morphometric analysis of dental models of newborns with cBCLP or BCLP + B. These analyses included metric analysis, coherent point drift-dense correspondence analysis, superprojection methods, and multivariate statistics. Dental casts were observed in two age categories, which were compared with each other. The first cast was obtained from each patient before ENC (T0, 5 ± 5 days) and the second one prior to palatoplasty (T1, 12 ± 6 months).ResultsFifty-two dental models obtained from 26 newborns with cBCLP and BCLP + B were evaluated. The results showed that over the 12-month period, alveolar clefts were narrowed in both cleft types due to anterior growth combined with the formative effect of suturing. This was confirmed by decreases in the dimensions of the right (T0 9.93 ± 2.80 mm, T1 6.64 ± 2.43 mm; p ≤ 0.003) and left (T0 10.71 ± 4.13 mm, T1 6.69 ± 4.29 mm; p ≤ 0.003) alveolar clefts in cBCLP patients. Similar reductions in alveolar cleft widths occurred on the left side (T0 11.69 ± 4.75 mm, T1 4.34 ± 2.97 mm; p ≤ 0.001) of BCLP + B patients, while on the right side, which was connected by a combined tissue bridge, there was non-significant narrowing of the alveolar cleft (T0 1.61 ± 1.34 mm, T1 1.04 ± 0.70 mm; p = 0.120). The ENC did not restrict posterior palatal growth, meaning that intertuberosity width was extended in cBCLP (T0 32.80 ± 3.15 mm, T1 35.86 ± 2.80 mm; p ≤ 0.001) and in BCLP + B neonates (T0 34.01 ± 2.15 mm, T1 36.21 ± 2.14 mm; p ≤ 0.004). Width and length measurements in the observed groups showed growth tendencies equivalent to those in noncleft or LOP patients. Palatal variability was greater in neonatal cBCLP, but was reduced during the monitored period, approximating that for BCLP + B. Regions with the most notable palatal growth were located primarily at the premaxilla and at the anterior and partially posterior ends of the maxillary segments.ConclusionEarly neonatal cheiloplasty had no negative effect on palatal growth in any direction. There was no reduction in the length or width of the palate during the first year of life, nor was there narrowing of the dentoalveolar arch. The formative effect of the operated lip on the anterior part of the palate was confirmed. This, in combination with the favorable growth, lead to closure of the alveolar cleft.     

Surgical treatment modality for facial esthetics in an obstructive sleep apnea patient with protrusive upper lip and acute nasolabial angle

For patients with severe obstructive sleep apnea syndrome (OSAS), maxillomandibular advancement (MMA) offers a good treatment option by physically expanding the skeletal framework. However, facial esthetics can be aggravated by MMA in patients with OSAS who have a normally positioned maxilla, a protrusive upper lip, and an acute nasolabial angle. Therefore, surgical treatment planning should be customized according to diverse skeletodental and soft-tissue patterns to produce a favorable change in facial esthetics and sleep function in patients with OSAS. In this case report, good treatment results were achieved in a young female patient with OSAS and skeletal Class II, a normally positioned maxilla, a protrusive upper lip, and acute nasolabial angle by impaction of the maxilla, autorotation/advancement of the mandible, and advancement of the chin. A customized flowchart for surgical treatment planning in OSAS that considers facial esthetics was suggested.     

Effects of growth on maxillary distraction osteogenesis in cleft lip and palate

PurposeThe objective was to analyze the effects of growth on the long-term result of maxillary distraction osteogenesis (DO) in cleft lip and palate (CLP).Patients and methodsRetrospective study of 24 CLP cases with long-term follow-up operated for maxillary DO using the Polley and Figueroa technique: 10 patients were distracted during growth, while 14 patients were operated after their growth spurt. Preoperative (T0), 6–12 months postoperative (T1), and ≥4 years postoperative (T2) cephalometric radiographs were evaluated. A classical cephalometric analysis was used to assess the treatment stability, and a Procrustes superimposition method was performed to assess local changes in the maxilla and the mandible.ResultsAt T0, the mean age was of 11.9 ± 1.4 years for growing patient, and 17.9 ± 3.5 years for patient treated after their growth spurt (P < 0.001). Between T0 and T1, a greater increase of the SNA was shown in growing patients (P = 0.036), but the relapse was more important between T1 and T2, with a significant decrease of the SNA (P = 0.002) and ANB (P = 0.032) compared to the patients treated after their growth spurt. Although not significant, growing patients showed greater rotations of their palatal plane and mandibular plane.ConclusionsMaxillary DO in CLP does not correct the growth deficit inherent to the pathology. Overcorrection of at least 20% is advised during growth.     

Respiratory and volumetric changes of the upper airways in craniofacial synostosis patients

To assess postoperative changes of the upper airway in a pediatric syndromic cranial-synostosis (SCS) population who underwent Le Fort III (LFIII) or frontofacial advancement by distraction osteogenesis (DO).Charts' review of 25 SCS infants presented at our tertiary-care children's hospital between January 2005 and December 2016 was performed. Preoperative (T0) and postoperative (T1) three-dimensional computed tomography (3D-CT) and polysomnography (PSG) were recorded. Differences between T0 and T1 airway volumes and changes in PSG data were analyzed.18 patients were included. The mean T0 and T1 volumes were calculated as 15.963 mm³ ± 7.181 SD and 24.550 mm³ ± 12.946 SD, respectively. Airway areas increased significantly (p < 0.05) in the total study-group by a median value of 8.004 mm³, together with a global 72.22% improvement in respiratory parameters.A statistically significant gain of the upper airway after LF III and DO in SCS patients has been demonstrated. Given the absence of a direct relationship between post-operative upper airway volume increase and OSAS degree improvement, further insights should consider performing T0 and T1 sleep endoscopy analysis to complete the diagnostic workup and to better assess the level of residual or recurrent upper airway obstruction in patients who experience unsuccessful surgical treatment.     

Evaluating the remodeling of condyles reconstructed by transport distraction osteogenesis in the treatment of temporomandibular joint ankylosis

PurposeThis study aimed to evaluate the remodeling of condyles reconstructed by transport distraction osteogenesis (DO) in patients with temporomandibular joint (TMJ) ankylosis.Patients and methodsTwenty-one patients with 26 affected joints were followed up for 34.1 ± 13.3 months. Patients who had undergone gap arthroplasty and TMJ reconstruction by DO were included. Maximal mouth opening (MMO) and occlusion were recorded. Computed tomography images were obtained preoperatively (T0), upon completing distraction (T1), upon removal of the distraction device (T2), and >2 years postoperatively (T3). The following were measured: mandibular ramus height, distance between gonion and Frankfurt plane (Go–FN), condylar width, and condyle–ramus angulation.ResultsOf the 21 patients, one showed re-ankylosis, while five exhibited anterior open bite. From T1 to T3, the total amount of resorption of ramus height reached up to 8.2 ± 4.6 mm (p < 0.001), in comparison with a total distraction length of 13.8 ± 4.1 mm; the mean resorption rate was 59.4%. Similarly, Go–FN decreased by 6.2 ± 4.0 mm (p < 0.001).ConclusionOur findings indicated that DO combined with gap arthroplasty was an effective method for the treatment of TMJ ankylosis to improve MMO. The reconstructed condyle exhibited a high frequency of resorption in height.     

An objective,quantitative, dynamic assessment of facial movement symmetry changes after orthognathic surgery

The aim of this study was to generate a quantitative dynamic assessment of facial movement symmetry changes after orthognathic surgery. Twenty-five patients diagnosed with skeletal class III malocclusion with facial asymmetry who underwent bimaxillary surgery were recruited. The patients were asked to perform a maximum smile that was recorded using a three-dimensional facial motion capture system preoperatively (T0), 6 months postoperatively (T1), and 12 months postoperatively (T2). Eleven facial landmarks were selected to analyse the cumulative distance and average speed during smiling. The absolute differences for the paired landmarks between the sides were analysed to reflect the symmetry changes. The results showed that the asymmetry index of the cheilions at T2 was significantly lower than that at T0 (P = 0.004), as was the index of the mid-lateral lower lips (P = 0.006). The mean difference in cheilions was 2.13 ± 1.41 mm at T0, 1.33 ± 1.09 mm at T1, and 1.00 ± 0.98 mm at T2. The facial total mobility at T1 was significantly lower than that at T0 (P < 0.001), while the total mobility at T2 was significantly higher than that at T1 (P = 0.012). The orthognathic surgical correction of facial asymmetry was able to improve the associated asymmetry of facial movements.     

Three-dimensional evaluation of long-term skeletal relapse following Le Fort I maxillary advancement surgery: a 2-year follow-up study

The aim of this study was to assess relapse following Le Fort I (LFI) maxillary advancement with superior or inferior repositioning at 2 years of follow-up. A total of 50 patients (26 female, 24 male; age range 15–56 years) with skeletal class II or III, who underwent bimaxillary surgery with LFI maxillary advancement in combination with either superior or inferior repositioning and also mandibular advancement/setback, were recruited. Preoperative (T0), immediate postoperative (T1), and 2-year postoperative (T2) cone beam computed tomography scans were acquired. Data were imported into a validated module to assess the skeletal movement (T0–T1) and relapse (T1–T2). Overall, the majority of the translational and rotational movements showed a relapse of <1 mm and <1°. Patients undergoing maxillary advancement with inferior repositioning in combination with mandibular advancement showed the highest amount of translational relapse in a superior (0.86 ± 0.85 mm, P < 0.0001) and posterior direction (?0.65 ± 1.11 mm, P < 0.0001). In relation to patients who received a bone graft, inferior repositioning with mandibular setback showed the highest maxillary relapse in a superior direction (1.20 ± 1.56 mm, P = 0.0719) with counterclockwise pitch rotation (2.15 ± 0.64°, P = 0.3759). Amongst the non-grafted procedures, superior repositioning with mandibular setback exhibited the highest relapse in a medial direction (1.38 ± 2.78 mm, P = 0.3981). Maxillary advancement was found to be a highly stable procedure with a lack of superoinferior stability in patients undergoing inferior repositioning.