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

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

Long-Term Clinical Assessment of Two Modifications of Tunnel Technique in Treatment of Cairo Recession Type 1 in Lower Jaw.

AIM: The aim of this study is to compare long-term results after using an MCAT (Modified Coronally Advanced Tunnel) with an SCTG (Subepithelial Connective Tissue Graft) or an MCAT with CM (Collagen Matrices) in the treatment of Cairo recession Type 1 in mandibular single-rooted teeth. MATERIAL AND METHOD: The study encompassed 80 recessions in 18 patients for whom an MCAT was combined with CM on one side of the mandible and with an SCTG on the contralateral one. The following clinical parameters were measured: gingival recession height (GR) and width (RW), probing depth (PD), clinical attachment level (CAL), width of keratinized tissue (KT), gingival thickness (GT), and mean (MRC). RESULTS: The MRC on the CM- and SCTG-treated sides was 55.25% and 82.35%, respectively. The SCTG side had a significantly greater improvement in MRC, GR, RW, KT, and GT compared to the CM side. The five-year results were stable relative to one-year observations. CONCLUSIONS: Both methods of treatment enable the achievement of stable long-term clinical results. Application of subepithelial connective tissue grafts is more effective relative to clinical parameters.

Assessment of soft-tissue vs hard-tissue changes after isolated functional genioplasty / Évaluation des modifications des tissus mous par rapport aux tissus durs après une génioplastie fonctionnelle isolée

Introduction: This study aimed to determine the vertical and horizontal soft-tissue vs hard-tissue changes after isolated functional genioplasty and to revisit hard-tissue remodeling at the symphysis. Methods: Seventy-five patients who underwent genioplasty as an isolated procedure at the end of their orthodontic treatment were divided into three groups on the basis of their age at surgery: < 15 years (group 1), 15-18 years (group 2) and ≥ 19 years (group 3). Patients were evaluated at three time points: immediately before surgery (T1), immediately after surgery (T2) and two years after surgery (T3). In addition, 25 patients who did not accept genioplasty, were age-matched with group 1, and had a follow-up radiograph two years after the end of their orthodontic treatment were used as a control group. Results: From T2 to T3, group 1 showed less forward horizontal hard-tissue and soft-tissue changes at pogonion (Pg) than the control group; however, no difference was noted for vertical changes at Me & Me'. From T1 to T3, the horizontal hard-tissue and soft-tissue changes at Pg were 6.39 mm and 6.72 mm, respectively, for surgical groups. Vertical hard-tissue change at menton (Me) showed a reduction of 1.63 mm (95% confidence interval [CI], -3.37 to 0.11) and 3.89 mm (95% CI, -5.83 to -1.95) in nongrowing female and male patients, respectively. The vertical soft-tissue change reduction was similar for nongrowing male and female patients (1.7 mm [95% CI, -2.96 to -0.45]). Soft-tissue thickness change at Pg (0.33 mm) was not significant. In contrast, a small but significant increase in soft-tissue thickness was noted at Me (0.54 mm). Linear regressions were calculated for all groups and allowed for predicting long-term soft-tissue changes (T3-T1) using the amount of surgical displacement (T2-T1). Conclusions: The horizontal hard-tissue change was stable for nongrowing patients, and the horizontal soft-tissue change was 92% of hard-tissue. Vertical soft-tissue change is less predictable. Variation of soft-tissue thickness after genioplasty can be explained by skeletal changes and the achievement of an unforced labial occlusion. These results support the functional and esthetic benefits of this surgery. Comparison with the control group showed that genioplasty does not change the growth pattern, and bone remodeling is likely to explain the difference noted at Pg.

Introduction: Cette étude avait pour but de déterminer les modifications verticales et horizontales des tissus cutanés par rapport aux tissus osseux après une génioplastie fonctionnelle isolée et d'évaluer le remodelage des tissus osseux au niveau de la symphyse. Méthodes: Soixante-quinze patients qui ont subi une génioplastie comme procédure isolée à la fin de leur traitement orthodontique ont été divisés en trois groupes sur la base de leur âge au moment de la chirurgie : moins de 15 ans (groupe 1), de 15 à 18 ans (groupe 2) et de 19 ans et plus (groupe 3). Les patients ont été évalués à trois moments : immédiatement avant la chirurgie (T1), immédiatement après la chirurgie (T2) et deux ans après la chirurgie (T3). En outre, 25 patients qui n'ont pas accepté la génioplastie, dont l'âge correspondait à celui du groupe 1 et qui ont subi une téléradiographie de profil de contrôle deux ans après la fin de leur traitement orthodontique ont été utilisés comme groupe témoin. Résultats: De T2 à T3, le groupe 1 a montré moins de changements horizontaux des tissus durs et mous vers l'avant au niveau du pogonion (Pg) que le groupe témoin ; cependant, aucune différence n'a été notée pour les changements verticaux au niveau de Me & Me'. De T1 à T3, les changements horizontaux des tissus osseux et cutanés à Pg étaient respectivement de 6,39 mm et 6,72 mm pour les groupes chirurgicaux. La modification verticale des tissus osseux au niveau du menton (Me) a montré une réduction de 1,63 mm (IC 95 %, -3,37 à 0,11) et de 3,89 mm (IC95 %, -5,83 à -1,95) chez les patients féminins et masculins sans croissance, respectivement. La réduction verticale de la modification des tissus mous était similaire chez les patients homme et femme qui ne sont pas en croissance (1,7 mm [IC 95 %, -2,96 à -0,45]). La modification de l'épaisseur des tissus mous à Pg (0,33 mm) n'était pas significative. En revanche, une augmentation faible mais significative de l'épaisseur des tissus cutanés a été observée à Me (0,54 mm). Des régressions linéaires ont été calculées pour tous les groupes et permettent de prédire les changements à long terme des tissus cutanés (T3-T1) en utilisant la quantité de déplacement chirurgical (T2-T1). Conclusions: Le changement horizontal des tissus osseux est stable pour les patients qui ne grandissent pas et le changement horizontal des tissus mous représente 92 % des tissus durs. Le changement vertical des tissus cutanés est moins prévisible. La variation de l'épaisseur des tissus cutanés après une génioplastie peut s'expliquer par les changements squelettiques et l'obtention d'une occlusion labiale non forcée. Ces résultats confirment les avantages fonctionnels et esthétiques de cette chirurgie. La comparaison avec le groupe témoin a montré que la génioplastie ne modifie pas le schéma de croissance et le remodelage osseux est susceptible d'expliquer la différence constatée à Pg.

Assessment of Inferior Alveolar Nerve Position at the Region of First and Second Mandibular Molars in Dentate and Edentulous Sites Using Cone Beam Computed Tomography: A Cross-Sectional Study.

Determining the position of the Inferior alveolar nerve (IAN) is an important factor prior to any surgical procedure in the mandible such as dental implant insertion and surgical tooth extraction. The aim of this study was to compare the position of IAN in partially edentulous patients in the lower first and second molars in both missing and dentate sides. A total of 200 CBCT scans were chosen randomly and examined. On cross-sectional views, the distance between lower border of IAN canal and upper border of inferior cortex of mandible (IC) were measured at the site of dentate and edentulous mandibular first and second molar. Paired-sample t-test was used to analyze and compare measurements on right and left sides. A total of 100 males and 100 females with mean age of 46.05 ± 12.33 years were included. The IC distance measured in four pairs were as follows: Pair one: 80 cases with right missing 6 (mean ± SD = 3.73 ± 1.29 mm) and left present 6 (mean ± SD = 3.42 ± 1.20 mm), Pair two: 20 cases with right present 6 (mean = 3.20 ± 1.48 mm) and left missing 6 (mean ± SD = 3.96 ± 1.62 mm), Pair three: 54 cases of right missing 7 (mean ± SD = 3.83 ± 1.74 mm) and left present 7 (mean ± SD = 3.62 ± 1.74 mm), and Pair four: 46 case of right present 7 (mean ± SD = 3.49 ± 1.56 mm) and left missing 7 (mean ± SD = 3.84 ± 1.42). The IAN was statistically more distant from inferior cortex of mandible in the edentulous parts compared with the non-edentulous part (P < 0.05). The IAN was positioned farther from the inferior cortex of mandible in edentulous sites compared with dentate parts. Cautious consideration is essential in any surgical procedure and dental implant operations to prevent IAN injury.

Lingual foramina of the anterior mandible in edentulous patients: CBCT analysis and surgical risk assessment.

OBJECTIVE: The mandible has various unnamed accessory foramina, and surgery is often performed in the symphyseal area. The aim of this study was to analyze the anatomical characteristics of mandibular lingual foramina with the objective of preventing clinical complications during implant surgery on an edentulous mandible. STUDY DESIGN: A total of 100 cone beam computed tomography scans of completely edentulous patients were included in this study. For each canal, nine measurements were recorded in millimeters: seven length or height measurements and two diameter measurements. The placement of a standard implant was simulated and whether the implant passed through the canal was noted. The results were analyzed by t-test and chi-squared at a significance level of 0.05. Pearson correlation analysis was used to assess the relationship between variables. RESULTS: We identified 309 foramina: 236 medial lingual foramina and 73 lateral lingual foramina. We found no significant relationship between the number of foramina and the age of the individuals, or between diameter and the age or gender of the individuals. The mandibular canal was injured in 32.7 % of implant placement simulations. CONCLUSION: The risk of injury to neurovascular bundles is increased in edentulous patients due to vertical bone resorption.

The Effect of Mandibular Angulation on Preoperative Assessment of Dental Implant Insertion at Premolar Region: CBCT Study.

Backgrounds: This study investigated the effect of mandibular angulation on the perioperative evaluation of the implant placement at the premolar region on panoramic reconstructed images using cone beam computed tomography (CBCT). Methods: A total of six dried anonymous human mandibles was included. Two implants were inserted in the left and right first premolar region. CBCT scans were obtained from each mandible at the standard position, +20° extension, and -20° flexion. The distance of the implant from the anterior loop of the inferior alveolar nerve and mental foramen was measured. Mean absolute error (MAE) of the distance of the implant from both anatomical landmarks was measured. The Wilcoxon matched-pair signed-rank test was used for the comparison of the measurements. All data were analyzed with the Stata program (version 15.1). Results: No statistically significant differences were found between the distance of the implant from the mental foramen and the anterior loop of the inferior alveolar nerve up to 20° extension and flexion at both sides of the mandible. (All p > 0.1) However, a variable range of MAE (SD) in the distance of the implant from different anatomical landmarks was found (0.9 ± 0.7 to 3.3 ± 2.1). Conclusions: We found no statistical difference in measurements of the distance of the implant from two anatomical landmarks at different head positions up to 20° extension and flexion. However, clinically, variable range in the distance of the implant from anatomical landmarks should be considered. Our findings could alert dentists of the possibility of error up to 20° extension and flexion on the perioperative evaluation of dental implant placement.

Novel strategy to predict high risk of inferior alveolar nerve injury during extraction of lower third molars based on assessment of computed tomographic images of multiple anatomical features.

Preoperative assessment is essential to prevent inferior alveolar nerve (IAN) injury during surgical extraction of the lower third molar (LM3). Here, we aimed to establish an assessment system to predict IAN injury during surgical extraction of the LM3. We conducted a retrospective cohort study on 115 patients diagnosed as 'high-risk' based on our previous risk assessment method involving three anatomical features of the inferior alveolar canal using computed tomographic (CT) images. We evaluated the occurrence of neurosensory impairment in these high-risk patients, and its association with novel anatomic features based on CT images. Neurosensory impairments were observed in 19 patients (16.5%). The inferior alveolar canal major diameter (p < 0.0001) and lingual bone thickness (p = 0.0039) were significantly associated with the occurrence of neurosensory impairment during LM3 extraction. Receiver operating characteristic curves were used to determine cut-off values of these quantitative factors to specifically predict IAN injury. Preoperative risk assessment with quantitative factors based on anatomical features observed on CT images may facilitate more appropriate surgical planning for patients at a high risk of IAN injury.

Assessment of soft-tissue vs hard-tissue changes after isolated functional genioplasty.

INTRODUCTION: This study aimed to determine the vertical and horizontal soft-tissue vs hard-tissue changes after isolated functional genioplasty and to revisit hard-tissue remodeling at the symphysis. METHODS: Seventy-five patients who underwent genioplasty as an isolated procedure at the end of their orthodontic treatment were divided into 3 groups on the basis of their age at surgery: <15 years (group 1), 15-18 years (group 2), and ≥19 years (group 3). Patients were evaluated at 3 time points: immediately before surgery (T1), immediately after surgery (T2), and 2 years after surgery (T3). In addition, 25 patients who did not accept genioplasty, were age-matched with group 1, and had a follow-up radiograph 2 years after the end of their orthodontic treatment were used as a control group. RESULTS: From T2 to T3, group 1 showed less forward horizontal hard-tissue and soft-tissue changes at pogonion (Pg) than the control group; however, no difference was noted for vertical changes at Me & Me'. From T1 to T3, the horizontal hard-tissue and soft-tissue changes at Pg were 6.39 mm and 6.72 mm, respectively, for surgical groups. Vertical hard-tissue change at menton (Me) showed a reduction of 1.63 mm (95% confidence interval [CI], -3.37 to 0.11) and 3.89 mm (95% CI, -5.83 to -1.95) in nongrowing female and male patients, respectively. The vertical soft-tissue change reduction was similar for nongrowing male and female patients (1.7 mm [95% CI, -2.96 to -0.45]). Soft-tissue thickness change at Pg (0.33 mm) was not significant. In contrast, a small but significant increase in soft-tissue thickness was noted at Me (0.54 mm). Linear regressions were calculated for all groups and allowed for predicting long-term soft-tissue changes (T3-T1) using the amount of surgical displacement (T2-T1). CONCLUSIONS: The horizontal hard-tissue change was stable for nongrowing patients, and the horizontal soft-tissue change was 92% of hard-tissue. Vertical soft-tissue change is less predictable. Variation of soft-tissue thickness after genioplasty can be explained by skeletal changes and the achievement of an unforced labial occlusion. These results support the functional and esthetic benefits of this surgery. Comparison with the control group showed that genioplasty does not change the growth pattern, and bone remodeling is likely to explain the difference noted at Pg.

Three-dimensional radiographic assessment of bone changes around posterior dental implants at native bone site in Gansu Province, Northwest of China: A retrospective cohort study.

PURPOSE: The aim of this study was to assess bone density and thickness changed following dental implant placement in the maxillary and mandibular jaws. Also, observe the form of bone loss around the implant and the relationship between preoperative bone density and bone thickness with bone loss around dental implants. METHODS: 65 patients, including 102 dental implants, were assessed in this study. CBCT was utilized to determine the bone condition (bone thickness and density at three levels (sub-crestal bone at 3 mm (CB3), 6 mm (CB6), and 9 mm (CB9)) before implant placement, and 2 to 3 years after placement, also determine the bone loss pattern. RESULTS: The difference in bone thickness was 0.32 ± 0.50 mm at CB3, 0.18 ± 0.40 mm at CB6, and 0.14 ± 0.07 mm at CB9. The change buccal bone density at CB3, CB6, and CB9 were 344.5 ± 278.9, 260.5 ± 276, and 138.9 ± 313.9 HU, respectively, and the change in lingual bone density was 252.7 ± 247, 179.9 ± 244.1, and 281 ± 4063 HU, respectively. Only the CB3 level showed a significant decrease in bone thickness (p < 0.001), and a change in bone density was observed at the three levels (p < 0.001). The means of vertical and horizontal bone loss were 0.19 ± 0.23 mm and 0.18 ± 0.22 mm, respectively. Splinted or adjacent dental implants have more horizontal bone loss, with statistically significant (p < 0.001). Age, gender, and implant position were not statistically related to the outcome variables. There was a negative correlation between the preoperative status of the bone condition and pattern bone loss, as indicated by Pearson's correlation coefficient. CONCLUSION: CBCT detected a significant bone thickness decrease was found only at the crestal third. A significant bone density increase was found at three levels around dental implants. Implant areas with higher bone thickness and density had less bone loss.

[Assessment of adaptive mechanisms to obturators of the upper jaw according to the data of electronic axiography and cone-beam computer tomography]. / Otsenka adaptatsii k obturiruyushchim protezam verkhnei chelyusti po dannym elektronnoi aksiografii i konusno-luchevoi komp'yuternoi tomografii.

THE AIM OF THE STUDY: Was to assess the adaptation of patients to obturator at different periods of adaptation using objective digital methods of analysis: axiography, cone-beam computer tomography, digital facial scans, and intraoral scanning. MATERIAL AND METHODS: The study comprised 17 patients with postoperative defects of the upper jaw at different periods of removable obturators usage. RESULTS: In 88.2% of the subjects limited mouth opening and displacement of the mandible to the healthy side was detected. Contracture as a complication can develop in the later stages of rehabilitation. CONCLUSION: A long-term rehabilitation of patients is recommended using simulators and special gymnastic exercises in order to prevent extra-articular contracture.

Three-dimensional assessment of facial asymmetry in Class III subjects. Part 1: a retrospective study evaluating postsurgical outcomes.

OBJECTIVE: The present study aimed to determine the site and severity of maxillomandibular asymmetry before and after orthognathic surgery in asymmetric patients. MATERIALS AND METHODS: Presurgery and postsurgery cone beam computed tomography (CBCT) data of 21 facial asymmetry patients (7 males and 14 females, mean age: 23.0 ± 3.36 years) with soft tissue chin deviation ≥ 3 mm who had undergone bimaxillary surgery were evaluated. Seven midline and twenty bilateral hard tissue landmarks were identified for the evaluation of facial asymmetry and outcomes were assessed against age- and gender-matched control subjects. RESULTS: In the asymmetry group, bilateral landmarks exhibited significant deviation in the mandible and midface regions. Before surgery, asymmetry was more severe at the mandibular midline and sites close to it, in the asymmetry group. Bimaxillary surgery proved to be highly effective, with a significant correction of the menton to a clinically normal value (2.90 mm, p < 0.001). After surgery, significant residual asymmetry was observed at the mental foramen (p = 0.001) in the R-L direction. Moreover, significant asymmetry persisted at the sigmoid notch (p = 0.001) in the S-I direction. CONCLUSIONS: Mandibular midline landmarks and chin peripheral regions contribute significantly to overall facial asymmetry characteristics. Despite significant correction after bimaxillary surgery, asymmetry persisted at several sites, thereby requiring secondary correction. Comprehensive 3D presurgical planning is central for asymmetry correction in a single surgery. CLINICAL RELEVANCE: The present study specifies the location of residual asymmetry sites and advocates the correction of those sites during initial surgery.

Comparison of surface- and voxel-based registration on the mandibular ramus for long-term three-dimensional assessment of condylar remodelling following orthognathic surgery.

OBJECTIVES: The purpose of the present study was to validate and compare the accuracy and reliability of surface- and voxel-based registration on the mandibular rami for long-term three-dimensional (3D) evaluation of condylar remodelling following Orthognathic Surgery. METHODS: The mandible was 3D reconstructed from a pair of superimposed pre- and postoperative (two years) cone-beam computerized tomography scans and divided into the condyle, and 21 ramal regions. The accuracy of surface- and voxel-based registration was measured by the absolute mean surface distance of each region after alignment of the pre- and postoperative rami. To evaluate the reliability, mean absolute differences and intraclass correlation coefficients (ICC) were calculated at a 95% confidence interval on volumetric and surface distance measurements of two observers. Paired t-tests were applied to statistically evaluate whether the accuracy and reliability of surface- and voxel-based registration were significantly different (p < 0.05). RESULTS: A total of twenty subjects (sixteen female; four male; mean age 27.6 years) with class II malocclusion and maxillomandibular retrognathia, who underwent bimaxillary surgery, were included. Surface-based registration was more accurate and reliable than voxel-based registration on the mandibular ramus two years post-surgery (p < 0.05). The interobserver reliability of using surface-based registration was excellent, ICC range [0.82-1.00]. For voxel-based registration, the interobserver reliability ranged from poor to excellent [0.00-0.98]. The measurement error introduced by applying surface-based registration for assessment of condylar remodelling was considered clinical irrelevant (1.83% and 0.18 mm), while the measurement error introduced by voxel-based registration was considered clinical relevant (5.44% and 0.52 mm). CONCLUSIONS: Surface-based registration was proven more accurate and reliable compared to voxel-based registration on the mandibular ramus for long-term 3D assessment of condylar remodelling following Orthognathic Surgery. However, importantly, the performance difference may be caused by an inappropriate reference structure, proposed in the literature, and applied in this study.

Risk Assessment of Lingual Plate Perforation in Anterior Edentulous Mandibular Region: A Virtual Implant Placement Study Using Cone-Beam Computed Tomography.

BACKGROUND: The aim of this study was to evaluate the prevalence of lingual cortical bone perforation caused by virtually placed implants on cone-beam computed tomography images in the edentulous mandibular canine region and determine the relationship between the morphological structure of the crest and the risk of perforation. METHODS: Eight hundred dental implants were virtually inserted on 100 qualified cone-beam computed tomography scans. Crests were divided into 4 groups according to the crest morphology as Type U, Type L, Type P, and Type C. The distance between the implant tip and lingual plate was measured using a digital caliper. Incidence of lingual plate perforation and proximity of the implant tip to the lingual plate were measured for 4 types of the alveolar crest. RESULTS: A total of 800 virtual implant applications were performed in 100 patients who met the inclusion criteria. The incidence of lingual plate perforation was found to be significantly higher in Type U crests than in the other types. It was also found to be statistically significantly higher in Type L crests than in Type P and Type C crests. When the relationship between implant length and perforation was evaluated, perforation in 14 mm implants was significantly higher than 8, 10, and 12 mm implants. CONCLUSIONS: According to the results of this study, it was determined that high rates of perforation occurred in the U and L type crests and 14 mm implants during implant surgery in the mandibular anterior edentulous region.

Assessment of an Artificial Intelligence Mandibular Osteotomy Design System: A Retrospective Study.

BACKGROUND: In this study, an AI osteotomy software was developed to design the presurgical plan of mandibular angle osteotomy, which is followed by the comparison between the software-designed presurgical plan and the traditional manual presurgical plan, thus assessing the practicability of applying the AI osteotomy software in clinical practices. METHODS: (1) Develop an AI osteotomy software: design an algorithm based on convolutional neural networks capable of learning feature point and processing clustering segmentation; then, select 2296 cases of successful 3D mandibular angle osteotomy presurgical plans, followed by using those 2296 cases to train the deep learning algorithm; (2) compare the osteotomy presurgical plan of AI osteotomy software and that of manual: first step: randomly selecting 80 cases of typical female head 3D CTs, and designing those 80 cases by means of AI osteotomy software designing (group A) and manually designing (group B), respectively; second step: comparing several indexes of group A and those of group B, including the efficiency index (time from input original CT data to osteotomy presurgical plan output), the safety index (the minimum distance from the osteotomy plane to the mandibular canal), the symmetry indexes (bilateral difference of mandibular angle, mandibular ramus height and mandibular valgus angle) and aesthetic indexes (width ratio between middle and lower faces (M/L), mandibular angle and mandibular valgus angle). RESULTS: The efficiency index: the design time of group A is 1.768 ± 0.768 min and that of group B is 26.108 ± 1.137 min, with P = 0.000; the safety index: The minimum distances from the osteotomy plane to the mandibular canal are 3.908 ± 0.361mm and 3.651 ± 0.437mm, p = 0.117 in groups A and B, respectively; The symmetry indexes: Bilateral differences of mandibular angle are 1.824 ± 1.834° and 1.567 ± 1.059° in groups A and B, respectively, with P = 0.278; bilateral differences of mandibular ramus height are 2.083 ± 1.263 and 2.965 ± 1.433, respectively, with P = 0.119 in groups A and B; Aesthetic indexes: M/L in groups A and B is 1.364 ± 0.074 and 1.371 ± 0.067, respectively, with P = 0.793; mandibular angles in groups A and B are 127.724 ± 5.800° and 127.242 ± 5.545°, respectively, with P = 0.681; Valgus angles in groups A and B are 11.474 ± 5.380 and 9.743 ± 4.620, respectively, with P = 0.273. CONCLUSIONS: With high efficiency, as well as safety, symmetry and aesthetics equivalent to those of a manual design, the AI osteotomy software designing can be used as an alternative method for manual osteotomy designing. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

An assessment of surgical and 10-year follow-up vertical changes after contemporary Class II and III orthognathic surgery.

INTRODUCTION: There has been little quantification of long-term vertical facial changes that might occur after contemporary orthognathic surgery. The aim was to assess ≥10-year follow-up vertical facial changes in patients after Class II and III orthognathic surgery. METHODS: Sequential lateral cephalograms of 162 former orthognathic patients had been gathered during routine clinical follow-up before any consideration was given to this current project. For this study, facial patterns were classified according to the Frankfort-mandibular plane and ANB angles and the horizontal distance from the pogonion to the nasion-perpendicular line. Chosen Class II and III groups were divided into longer and shorter-face subgroups on either side of the average FMP angle (longer face >25°). The assessment was made from already-available lateral cephalograms taken before treatment, at debanding, and ≥10-year clinical follow-up. RESULTS: After obvious improvement with orthodontics and orthognathic surgery, mean FMP angles seemed to move back toward the preexisting vertical dimensions in both Class II and III longer and shorter-face groups over the next decade. However, there was considerable individual variation around the means. Similar posttreatment changes were seen with the ANB angle and the distance from pogonion to the nasion-perpendicular line. Significant correlations were found between the amount of preexisting discrepancy for these variables and their changes during and after treatment. CONCLUSIONS: Significant planned vertical mandibular changes are achieved with Class II and III surgery. However, in the longer term, it would seem that, in general, there is a tendency for postsurgical vertical facial proportions to revert somewhat toward the pretreatment proportions. Wide individual variation in posttreatment musculoskeletal behavior should be expected. Despite these changes, it does not necessarily mean that there should be an expectation of long-term dentofacial collapse after such treatment.

Mandible reconstruction with free fibula flaps: Accuracy of a cost-effective modified semicomputer-assisted surgery compared with computer-assisted surgery - A retrospective study.

A new individualized, cost-effective, modified semi-computer-assisted surgery (MSCAS) concept for free fibular flap mandibular reconstruction is reported and compared with the computer-assisted surgery (CAS) concept. Patients were divided into two groups and retrospectively reviewed. In the MSCAS and CAS groups, intraoperative guides were created using computer-aided design with manual fabrication and computer-aided design and manufacturing, respectively. Differences in specific linear and angular parameters on pre- and postoperative computed tomography scans were calculated for morphometric comparison, and clinical parameters and efficiency were analysed. RESULTS: Eighteen patients (CAS, 7; MSCAS, 11), were included. The morphometric comparison showed no significant differences between the groups. The mean deviation of the mandibular ramus length, body length, width 1 and width 2 was 0.82 ± 0.29 mm, 1.84 ± 0.43 mm, 1.89 ± 0.61 mm and 1.45 ± 0.61 mm in the CAS group versus 1.56 ± 0.54 mm, 1.72 ± 0.33 mm, 2.24 ± 0.55 mm and 2.36 ± 0.50 mm in the MSCAS group (p = 0.7804, p = 0.9997, p = 0.9814 and p = 0.6334). The mean deviation of the sagittal, axial and coronal mandibular angles was 1.56 ± 0.48°, 1.93 ± 0.50° and 2.15 ± 0.72° in the CAS group versus 2.19 ± 0.35°, 1.86 ± 0.35° and 1.94 ± 0.55° in the MSCAS group (p = 0.7594, p = 0.9996 and p = 0.9871). There were no significant differences in clinical parameters, efficiency or postoperative complications between the groups. CONCLUSION: The accuracy and operative efficiency of the MSCAS concept are comparable to those of the more expensive CAS concept. Therefore, in times of increasing clinical costs, this concept might be an adequate and inexpensive alternative to preoperative CAS.

The Assessment of Neurosensory Disturbance Following Bilateral Sagittal Split Osteotomy With Subjective and Three-Dimensional Evaluation.

PURPOSE: Inferior alveolar neurosensory disturbance (IAND) is the most common complication of bilateral sagittal split osteotomy (BSSO). The aim of the present study was to evaluate IAND with subjective tests postoperatively and assess the relationship between three-dimensional measurements of the mandibular canal (MC) and IAND. METHODS: Eighteen patients (Mean age: 24.05 ±â€Š5.85 years) treated with BSSO were retrieved from the archive. Subjective tests (light touch, tactile sensitivity, 2-point discrimination, brush-stroke directional discrimination, sharp/blunt discrimination, dental vitality, questionnaire) and three-dimensional measurements related to MC and fixation screws were done postoperatively (on average 20.43 ±â€Š8.76 months after surgery). Statistical significance was set at P  < 0.05. RESULTS: Subjective test results were found compatible with each other except brush-stroke directional discrimination test. According to the questionnaire, IAND was apparent in all patients immediately after surgery, and recovery after 1 to 2 years was statistically significant ( P  < 0.05). Preoperative ramus width, medial and lateral cancellous bone lengths, the decrease in MC length, and the presence of screw in MC were not related to IAND ( P  < 0.05). CONCLUSIONS: There is a high incidence of IAND following BSSO, and the subjective tests are efficient to evaluate the disturbance. Spontaneous recovery of the nerve occurs during the follow-up periods. Instead of preoperative measurements of bone thickness, MC length, and the position of fixation screws, the surgical procedure seems to be more important in IAND occurrence.

Presurgical Assessment of Anatomical Landmark Position Using Two Views of Cone Beam Computed Tomography: A Comparative Radiological Study.

BACKGROUND: Cone beam computerized computed tomography (CBCT) has been widely indicated in dental implant procedure. The first step that the doctors should perform in local hospitals is to use orthopantomography for surgical planning to avoid and limit the risk of complications. As a result, determining the magnification amount of orthopantomography to achieve a precise diagnosis is clinically important. This study investigated the difference in measurement of the mental foramen (MF) position before dental surgery using 2 views of CBCT. MATERIALS AND METHODS: Cone beam computed tomography scan was performed for 100 patients who required implant placement. In the panoramic and three-dimensional views of CBCT, the vertical distance between the margin of the mandible and the lower border of MF, and the horizontal distance between the mandibular symphysis and the mesial anterior border of MF were calculated. The differences between the 2 views were compared using Wilcoxon-rank U test with P value ≤ 0.05 considered statistically significant. RESULTS: The findings of this study showed a substantial statistical difference in the horizontal distance for the dentate patients in panoramic and three-dimensional views (22.7 ±â€Š3.04 versus 21.1 ±â€Š1.6), (22.5 ±â€Š2.4 versus 20.9 ±â€Š1.5) and left side (22.4 ±â€Š2.8 versus 21.2 ±â€Š1.6), (22.4 ±â€Š2.8 versus 20.6 ±â€Š1.4) of both genders. Concerning the vertical distance, a significant difference was also observed in the dentate (12.1 ±â€Š2.1 versus 11.1 ±â€Š1.4), (10.6 ±â€Š1.4 versus 9.6 ±â€Š1.3) and left side of the jaw (11.6 ±â€Š1.95 versus 10.9 ±â€Š1.2), (10.5 ±â€Š1.2 versus 9.96 ±â€Š1.4) for both genders in both views. In the edentulous and right side of the jaw, however no statistical difference was observed between male and female patients in terms of horizontal and vertical measurements.

Assessment of Robot-Assisted Mandibular Contouring Surgery in Comparison With Traditional Surgery: A Prospective, Single-Center, Randomized Controlled Trial.

BACKGROUND: Few clinical studies on robot-assisted surgery (RAS) for mandibular contouring have been reported. OBJECTIVES: The aim of this study was to follow the long-term effectiveness and safety of RAS for craniofacial bone surgery. METHODS: This small-sample, early-phase, prospective, randomized controlled study included patients diagnosed with mandibular deformity requiring mandibular contouring surgery. Patients of both genders aged 18 to 30 years without complicated craniofacial repair defects were enrolled and randomly assigned in a 1:1 ratio by a permuted-block randomized assignments list generated by the study statistician. The primary outcomes were the positioning accuracy and accuracy of the osteotomy plane angle 1 week after surgery. Surgical auxiliary measurement index, patient satisfaction scale, surgical pain scale, perioperative period, and complications at 1 week, 1 month, and 6 months after surgery were also analyzed. RESULTS: One patient was lost to follow-up, resulting in a total of 14 patients in the traditional surgery group and 15 in the robot-assisted group (mean [standard deviation] age, 22.65 [3.60] years). Among the primary outcomes, there was a significant difference in the positioning accuracy (2.91 mm vs 1.65 mm; P < 0.01) and angle accuracy (13.26º vs 4.85º; P < 0.01) between the 2 groups. Secondary outcomes did not significantly differ. CONCLUSIONS: Compared to traditional surgery, robot-assisted mandibular contouring surgery showed improved precision in bone shaving, as well as higher safety.