Three-dimensional facial soft-tissue changes after surgical orthodontics in different vertical facial types of skeletal Class III malocclusion: A retrospective study.

The study compared the soft-tissue response to hard-tissue movement among different Class III vertical facial types after orthognathic surgery (OGS). The study included 90 consecutive adult patients with skeletal Class III malocclusion who underwent two-jaw OGS. Patients were divided into three groups (high, medium, and low angle) based on the presurgical Frankfort-mandibular plane angle. Cone-beam computerized tomographs were taken before surgery and after debonding. Soft- and hard-tissue linear and angular measurements were performed using three-dimensional reconstruction images. One-way analysis of variance was used for intergroup comparisons. Soft tissue tended to respond more to hard-tissue movement in the lower lip area in patients with low angle (mean = 0.089, SD = 0.047, p = 0.023), whereas no significant difference was observed for other sites. Consistently, L1/Li thickness increased most significantly in the high-angle group (mean = 1.98, SD = 2.14, p = 0.0001), and B/Si thickness decreased most significantly after surgery (mean = 2.16, SD = 2.68, p = 0.016). The findings suggest that the high-angle group had a higher chance of undergoing genioplasty to enhance chin contour. Different OGS plans should be considered for different Class III vertical facial types.

Does cleft lip and palate affect the severity of malocclusion?

OBJECTIVE: The purpose of this study was to evaluate the 3D anatomical features of unilateral (UCLP) and bilateral (BCLP) complete cleft lip and palate with those of skeletal Class III dentofacial deformities. MATERIALS AND METHODS: In total, 92 patients were divided into cleft and noncleft groups. The cleft group comprised 29 patients with UCLP and 17 patients with BCLP. The noncleft group comprised 46 patients with Class III dentofacial deformities. 3D anatomical landmarks were identified and the corresponding measurements were made on the cone-beam computed tomography (CBCT). RESULTS: The differences between the affected and unaffected sides of the patients with UCLP were nonsignificant. The differences between the patients with UCLP and BCLP were nonsignificant except for the SNA angle. Significant differences between the patients with clefts and Class III malocclusion were identified for the SNA, A-N perpendicular, and A-N Pog line, indicating that the maxillae of the patients in the cleft group were more retrognathic and micrognathic. Relative to the noncleft group patients, the cleft group patients had a significantly smaller ramus height. CONCLUSION: The affected and unaffected sides of the patients with UCLP did not exhibit significant differences. The maxillae of the patients with UCLP were significantly more retrognathic than those of the patients with BCLP. The maxillae and mandibles of the patients in the cleft group were more micrognathic and retropositioned relative to those of the noncleft Class III patients. CLINICAL RELEVANCE: The maxillary and mandibular findings indicated greater deficiencies in the patients with UCLP or BCLP than in those with skeletal Class III malocclusion. Appropriate surgical design should be administered.

Clockwise versus counterclockwise rotation in bimaxillary surgery: 3D analysis of facial soft tissue outcomes.

PURPOSE: This study aimed to compare facial 3D soft tissue changes in subjects with Class III deformities who underwent bimaxillary clockwise (CW) and counterclockwise (CCW) rotational orthognathic surgery. METHODS: Asian Class III subjects who completed bimaxillary surgical orthodontic treatments were enrolled and categorized into CW and CCW groups based on maxillary occlusal plane alterations. Preoperative and 9-month follow-up cone-beam computed tomography (CBCT) and 3D stereophotogrammetry were obtained, superimposed, and quantified for skeletal movements and soft tissue changes in six facial regions. Inverse probability of treatment weighting (IPTW) adjusted for potential confounding factors. RESULTS: Thirty-seven subjects were included (CW group, n = 20; CCW group, n = 17). Postsurgical chin volume significantly reduced in the CW group compared to the CCW group (mean difference 6362 mm3; p = 0.037), and intergonial width significantly decreased in the CW group (mean difference 6.2 mm; p = 0.005). The postoperative alar width increased by 1.04 mm and 1.22 mm in the CW and CCW groups, respectively (p = 0.70). However, these changes were not significantly correlated to the direction of MMC pitch. CONCLUSION: Clockwise rotation of the bimaxillary complex demonstrated a significant advantage in reducing chin volume and intergonial width compared to counterclockwise rotation, leading to a reduced frontal lower face width among Asian Class III subjects.

Dental Occlusion Characteristics for Treatment Decision-Making Regarding Surgery-First Approach in Orthodontics.

The surgery-first approach (SFA) is conducted to decrease the difficulty and duration of orthodontic treatment by correcting the skeletal discrepancy at the initial stage of treatment. However, the indication of the SFA has not been well defined yet. This study explored the dental occlusion characteristics for treatment decision-making regarding the SFA. A total of 200 skeletal Class III patients were consecutively collected and divided into two groups: the orthodontic-first approach (OFA) group and the SFA group. The pretreatment digital dental models and lateral cephalograms were measured. Logistic regression was completed and receiver operating characteristic (ROC) curves were obtained to predict the probability of the SFA. Results showed that the ROC model with L1-MP, upper and lower arch length discrepancy, overbite, and asymmetric tooth number as influencing factors revealed that the sensitivity and specificity for determining SFA were 83.0% and 65.0%, respectively; the accuracy of prediction was 75.0%. In conclusion, our findings indicate that the six measurements from digital dental models and lateral cephalograms can be effectively applied in treatment decision-making for the SFA with satisfactory accuracy.

Evaluation of pharyngeal airway space after orthodontic extraction treatment in class II malocclusion integrating with the subjective sleep quality assessment.

Orthodontic treatment with premolar extractions is typically used to relieve dental crowding and retract anterior teeth for lip profile improvement. The aim of the study is to compare the changes in regional pharyngeal airway space (PAS) after orthodontic treatment with Class II malocclusion and to identify the correlations between questionnaire results and PAS dimensions after orthodontic treatment. In this retrospective cohort study, 79 consecutive patients were divided into normodivergent nonextraction, normodivergent extraction, and hyperdivergent extraction groups. Serial lateral cephalograms were used to evaluate the patients' PASs and hyoid bone positions. The Pittsburgh Sleep Quality Index and STOP-Bang questionnaire were used for sleep quality evaluation and obstructive sleep apnea (OSA) risk assessment, respectively, after treatment. The greatest airway reduction was observed in hyperdivergent extraction group. However, the changes in PAS and hyoid positions did not differ significantly among three groups. According to questionnaire results, all three groups had high sleep quality and low risk of OSA, with no significant intergroup differences. Moreover, pretreatment-to-posttreatment changes in PAS were not correlated with sleep quality or risk of OSA. Orthodontic retraction with premolar extractions nither exhibit significant reduction in airway dimensions nor increase their risk of OSA.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Affect Surgical Movement and Stability?

PURPOSE: Orthognathic surgery (OGS) using the surgery-first approach (SFA) can decrease treatment time and increase patient satisfaction. Clockwise rotation (CWR) of the maxillomandibular complex to correct mandibular prognathism leads to optimized functional, aesthetic, and stable outcomes. This study examined the combined effect of SFA and CWR of the maxillomandibular complex to correct mandibular prognathism by comparing the surgical movement before (T0) and immediately after OGS (T1) and the stability between T1 and 12 months after OGS (T2). METHODS: This prospective cohort study enrolled patients with skeletal Class III malocclusion who underwent SFA involving Le Fort I osteotomy and bilateral sagittal split osteotomy, with or without genioplasty. Based on the occlusal plane (OP) change at T0-T1, the patients were divided into CWR (OP > 4°) and control (C) groups (OP ≤ 4°). The predictor variable was OP change at T0-T1. The primary outcome variable was the stability of pogonion (Pog) at T1-T2. The covariates included demographic factors, cephalometric measurements (anterior facial height, posterior facial height, OP, mandibular plane angle, incisor mandibular plane angle, overjet, and overbite), and 3-dimensional landmark displacement (anterior nasal spine, A-point, upper central incisor, upper first molar, lower central incisor, lower first molar, Pog, gonion, and condylion). An independent t-test was used to compare between these 2 groups when appropriate. The level of significance was set at P < .05. RESULTS: The sample included 28 patients (17 females) in the C group and 36 (24 females) in the CWR group; the mean ages were 23.89 ± 3.35 and 24.08 ± 4.02 years, respectively. For the surgical movement at T0-T1, the CWR group showed an association with vertical movement of the maxilla at posterior nasal spine (P = .005), anterior nasal spine (P < .001), and A-point (P < .001) and horizontal backward movement of the mandible at B-point (P < .001), Pog (P < .001), and gonion (P = .042). At T1-T2, all landmarks remained stable without clinically significant difference between the 2 groups. CONCLUSION: Surgical movement in the CWR group could vertically displace the maxilla and setback mandible more than that in the C group. Postoperative skeletal stability remained the same between the 2 groups at 1 year after OGS.

Does the floor of the maxillary sinus affect tooth movement for premolar extraction space closure?

OBJECTIVE: The study investigated orthodontic tooth movement by comparing various horizontal and angular measures of the teeth having different sinus-root relationship (SRR) of patients undergoing first premolar extraction treatment protocols. MATERIALS AND METHODS: This retrospective cross-sectional study included 45 Taiwanese adult patients, classified as the control group (n = 15) and the sinus group (n = 30) according to SRR. The control group had type I SRR (sinus floor above the level connecting the buccal and palatal root apices), whereas the sinus group included patients with type V SRR (the buccal and palatal root displayed apical protrusion into the sinus floor). Morphology was identified using pretreatment orthopantomograms. Lateral cephalometric measurements were conducted before treatment (T1) and at debonding (T2). RESULTS: Post debonding, there were no statistically significant difference in the two groups. However, the incisors in the control group became marginally more upright than those of the sinus group, and the molars demonstrated tipping movement with minimal anchorage loss in the sinus group than in the control group. The total treatment time was not significantly different between the 2 groups. CONCLUSION: The study revealed that the sinus-root relationship does not affect the orthodontic tooth movement. However, a more extensive 3-D study with larger sample size is strongly recommended before coming to any conclusion. CLINICAL RELEVANCE: The lining of the floor of the maxillary sinus does not affect the orthodontic tooth movement.

Comparison of 3-dimensional postoperative dental movement in Class III surgical correction with and without presurgical orthodontic treatment.

BACKGROUND: Surgery-first approach (SFA) is an emerging concept that surgically reposition the jaw bones without presurgical orthodontic treatment phase. The study investigated 3D dental movement in the postoperative orthodontic phase with orthodontic-first (OF) and SFA in orthognathic surgery (OGS). METHODS: This study included consecutive 40 patients (20, SF group; 20, OF group) skeletal Class III who underwent 2-jaw OGS correction. The data of cone-beam computed tomography were acquired at 3 stages with the scan of dental models to replace the dentition of the craniofacial images; at before OGS (T0), 1 week after OGS (T1) and at the completion of treatment (T2). The skeletal changes were obtained by overall superimposition. The post-operative dental movement was measured by 3D regional superimposition between T1 and T2. RESULTS: There were no significant difference in the postsurgical orthodontic movement in both groups except significant upper and lower molars extrusion by 2 mm in the SF group. Both groups exhibited no significant difference in mandibular stability in sagittal and vertical directions. The amount of extrusion in the molars was correlated with a postoperative sagittal mandibular forward movement. The total treatment duration was significantly shorter 230 days in the SF group. CONCLUSION: The completion of the orthodontic treatment after OGS in the SFA was mainly accomplished through molar extrusive movement in both arches. The surgical setup of dental occlusion with 4 mm posterior open bite could be corrected during the postsurgical orthodontics in SFA through molar extrusion. The dental occlusion outcome was no different between OF and SFA.

Accuracy of Mandible-First versus Maxilla-First Approach and of Thick versus Thin Splints for Skeletal Position after Two-Jaw Orthognathic Surgery.

BACKGROUND: The aim of this study was to investigate the accuracy of bimaxillary orthognathic surgery regarding different sequencing (maxilla-first or mandible-first surgery) and different thicknesses of intermediate splints. METHODS: This retrospective cohort study evaluated the accuracy of postoperative outcome in accordance with virtual planning in 57 patients requiring bimaxillary osteotomies with different operation sequence: maxilla-first (n = 31) or mandible-first (n = 26) surgery. The effect of different splint thicknesses (i.e., thick, n = 22; and thin, n = 35) was also evaluated. The 1-week postoperative cone-beam computed tomographic craniofacial images were superimposed onto preoperative simulated images to measure the discrepancy of the three-dimensional cephalometric landmarks. RESULTS: Neither sequencing approach differed in overall accuracy (1-week postoperative to preoperative simulated image discrepancy): maxilla-first, 1.69 ± 0.53 mm; versus mandible-first, 1.44 ± 0.52 mm. In detailed comparison, mandible-first surgery resulted in more accuracy in the vertical dimension. Thick intermediate splints provided better control (less error) of upper central incisors in the sagittal position (thick splint, 1.38 ± 1.17 mm; thin splint, 2.13 ± 1.38 mm). However, overall accuracy was not affected by splint thickness. Conditions affecting sequencing predilection included skeletal class III with vertical excess, maxillary down-grafting, counterclockwise rotation of the maxillomandibular complex, and simulated mandibular opening for splint fabrication clearance. CONCLUSIONS: Despite both means of sequencing being performed similarly, mandible-first surgery was more precise in the vertical dimension. Thick intermediate splints seemed to yield better control of central incisors in the sagittal position. However, under appropriate selection of intermediate splints to maintain interim condylar position, splint thickness has no effect on overall accuracy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Are Signs of Degenerative Joint Disease Associated With Chin Deviation?

PURPOSE: Degenerative joint changes commonly affect the temporomandibular joint (TMJ) and can result in chin deviation. However, the extent of degenerative TMJ changes and chin deviation has not been well-characterized. The present study sought to correlate degenerative TMJ changes with condylar volume, grayscale measures, and chin deviation. MATERIALS AND METHODS: The present cross-sectional study had enrolled women with skeletal Class III malocclusion. Cone-beam computed tomography scans were acquired preoperatively. For each condyle, degenerative TMJ signs were analyzed and the condylar volume and grayscale were measured. The predictor variable was the presence of degenerative TMJ signs, classified as categorical data: 0, if none; 1, only present in 1 joint; and 2, present in both joints. The primary outcome variable was a chin deviation of 3 mm or more. Other associated variables were grouped by age, cephalometric data, and 3-dimensional condylar measurements. Descriptive bivariate statistics were computed, and univariate and multiple logistic regression analyses were conducted to identify any associations between degenerative TMJ disease and chin deviation. RESULTS: We included 85 patients, who were classified into 2 groups: less than 3 mm of chin deviation (n = 43) and 3 mm or more of chin deviation (n = 42). The presence of more than 10 degenerative TMJ signs was significantly associated with the presence of 3 mm or more of chin deviation (P < .001). In multiple regression models, the presence of subcortical sclerosis in 1 joint and in both joints (adjusted odds ratio [OR], 3.698; 95% confidence interval [CI], 1.051 to 13.012; adjusted OR, 5.001; 95% CI, 1.461-17.119, respectively) correlated significantly with the presence of 3 mm or more of chin deviation (P < .05). The volume difference between the 2 condyles was significantly greater in the group with more than 10 degenerative TMJ signs and 3 mm or more of chin deviation than in the group with 10 or fewer degenerative TMJ signs and less than 3 mm of chin deviation (P = .016 and P < .001, respectively). CONCLUSIONS: In women with skeletal Class III malocclusion, the presence of more than 10 degenerative TMJ signs increased the prevalence of 3 mm or more of chin deviation. The presence of subcortical sclerosis in either 1 or both joints and volume differences between the 2 condyles were associated with greater chin deviation.

History and Evolution of Orthognathic Surgery at Chang Gung Craniofacial Center: Lessons Learned From 35-Year Experience.

BACKGROUND: Modern orthognathic surgery (OGS) was established on the basis of contributions from multidisciplinary centers worldwide. This study reports the history and evolution of OGS at the Chang Gung Craniofacial Center (CGCC) and identifies the lessons learned from 35 years of experience. METHODS: The total number of OGS procedures managed by the CGCC multidisciplinary team between 1981 and 2016 was determined. The database of the senior author (Y.-R.C.) was reviewed for consecutive OGS procedures performed between 2003 and 2016. A literature review was also performed to retrieve the contributions from the total CGCC team. RESULTS: The 35 years of experience at a single center and 13-year experience of a single surgeon corresponded to 8073 and 2883 OGS procedures, respectively. Moreover, 53 peer-reviewed articles were reviewed. Teamwork (plastic surgeons, orthodontists, and anesthetists) ensured an optimal balance between occlusion functional and facial aesthetic outcomes, with patient safety ensured and a minimum of OGS-related complications. Progression from the conventional orthodontics-first approach to the surgery-first OGS approach decreased the overall treatment time. Transition from 1-jaw to 2-jaw surgery enabled more consistent aesthetic outcomes to be achieved. Conversion from the 2-splint to the single-splint technique enabled development of a more precise tridimensional simulation plan and surgical execution, including in challenging scenarios such as malocclusion associated with facial asymmetry. Clockwise pitch rotation of the maxillomandibular complex has been designed for facial aesthetic purposes in class III malocclusion, whereas counterclockwise pitch rotation of the maxillomandibular complex improves airway function in those with sleep apnea. CONCLUSIONS: The lessons learned from experience and outcome-based articles reveal that OGS has successfully evolved at the CGCC, with a balance being achieved between functional and aesthetic outcomes and effective decreases in the burden of care (ie, morbidity, complications, and treatment time).

Investigate the oral health impact and quality of life on patients with malocclusion of different treatment needs.

BACKGROUND: This study compared oral health impacts and QoL among patients with different malocclusion types and a normal population by using self-report questionnaires. METHODS: In this cross-sectional study, 214 healthy adults were divided into 3 groups: (1) Normal, control group; (2) ORTHO, patients who received orthodontic treatment; and (3) OGS group, patients who received orthognathic surgery (OGS). The timing of measurement were at the initial stage of the orthodontic therapy and before surgery. Two questionnaires and one additional item were used: the 36-item Short Form Health Survey (SF-36) for QoL, the 14-item Oral Health Impact Profile (OHIP-14) for oral health-related QoL (OHRQOL) and one additional item for aesthetic evaluation. Descriptive and inferential statistical analyses were used to compare the 3 groups. The effects of 3 malocclusion types, gender, age, and facial asymmetry in the OGS group were also evaluated. RESULTS: The ORTHO and OGS groups had higher negative impacts than did the Normal group in the OHIP-14, but not much difference in the SF-36. The item of aesthetics related to oral health impact was the lowest in the OGS group. The patients in the ORTHO group with a Class II malocclusion were most dissatisfied in the SF-36 and OHIP-14. In the OGS group, the women dissatisfied in the OHIP-14 and the aesthetic. The older patients had higher negative impacts in the OHIP-14 than the younger patients. The patients with facial asymmetry did not suffer higher negative impacts than did the patients with a symmetrical face in the SF-36 and OHIP-14. CONCLUSIONS: The majority of the patients who required orthodontics or OGS reported a higher negative impact in the OHIP-14 compared with the normal controls, but not in the SF-36. Class II malocclusion suffered from highest psychological stress and aesthetic sensitivity than the other two subgroups in the ORTHO group.

Female Facial Attractiveness Assessed from Three-Dimensional Contour Lines by University Students.

BACKGROUND: Three-dimensional (3D) images could provide more accurate evaluation for facial attractiveness than two-dimensional (2D) images. The 3D facial image could be simplified into gray scale 3D contour lines. Whether female facial attractiveness could be perceived in these simplified 3D facial contour lines should be determined. METHODS: A series of 100 2D photographs (one frontal and two lateral views) and 3D contour lines extracted from 3D facial images of females were projected onto a screen. Each image presentation lasted 5 s, and the evaluators marked their impression of each image's facial attractiveness on a five-point Likert scale within 3 s of its presentation. The evaluation of the 3D contour lines was performed twice, 2 weeks apart. The evaluators were university students. RESULTS: High consistency (r = 0.92) was found for the first and second evaluation of 3D facial contour lines for female facial attractiveness. The judgments of unattractive face were more consistent than the judgments of attractive face. Male students tended to give lower scores than female students in the evaluation of female facial attractiveness. CONCLUSIONS: Female facial attractiveness could be evaluated by 3D facial contour lines. 3D facial contour lines should be one of the key factors of facial attractiveness.

Enhanced Surgical Outcomes in Patients With Skeletal Class III Facial Asymmetry by 3-Dimensional Surgical Simulation.

PURPOSE: With the advance of image fusion techniques, the creation of 3-dimensional (3D) virtual head and 3D surgical simulations has provided previews of surgical procedures. The aim of this study was to investigate the surgical outcomes in patients receiving orthognathic surgery (OGS) with the guidance of 3D computer-assisted surgical simulation. PATIENTS AND METHODS: The study included 34 consecutive patients (15 men and 19 women; age, 18.1 to 33.0 yr) with skeletal Class III facial asymmetry who underwent bimaxillary OGS. One-week postoperative cone-beam computed tomographic craniofacial images (Ta) were constructed and superimposed on preoperative simulated virtual images (Ts) at the cranial base and surfaces of the frontal and periorbital regions. The 3D cephalometric landmarks were measured relative to 3 reference planes. The outcomes among different experience levels of surgeons also were compared. RESULTS: Although the mean values between Ta and Ts were small, statistical differences were observed in the center of maxillary and mandibular incisors and the B point relative to the midline and in the maxillary first molar in vertical distances, sagittal dentoskeletal dimensions, and pitch angles. The root mean square deviations (RMSDL) of measurement variables relative to center landmark accuracy were 1.5 and less than 2 mm at the maxilla and mandible, respectively. RMSDL greater than 2 mm was located at the maxillary first molar in the vertical distance and in the sagittal dimension at the anterior nasal spine and B point. Variables related to centering the midline structures were highly inter-related. The roll angle deviation was associated with centering the midline landmarks. The yaw angle deviation was not associated with midline correction. CONCLUSION: With guidance from 3D surgical simulation, surgeons could achieve similar outcomes to correct facial asymmetry regardless of their years of practice.

An integrated surgical protocol for adult patients with hemifacial microsomia: Methods and outcome.

BACKGROUND: Hemifacial microsomia (HFM) features hypoplasia and asymmetry in skeletal as well as soft tissue, and correction of the deformity is difficult in terms of aesthetic outcome. The purpose of this study is to examine the validity of an integrated treatment protocol for correction of this facial deformity. PATIENTS AND METHODS: A retrospective study was performed on adult HFM patients who received two-jaw orthognathic surgery combined with facial contouring procedures in the first stage, and fat injection for the residual facial deficiency in the second stage. Inclusion criteria were patients treated by the same surgeon and follow-up at least 6 months. The demographic, perioperative, and follow-up data were collected. We defined a facial surface area discrepancy index (FDI) for objective assessment of the symmetry between the affected and non-affected side, and utilized visual analogue scale (VAS) for subjective evaluation of facial asymmetry before and after surgical treatment. RESULTS: A total of 14 patients were included. The mean age at orthognathic surgery was 21.7 years. Four patients were categorized as Pruzansky-Kaban type I, while the remaining 10 patients were type II (7 patients type IIA, 3 patients type IIB). Fat injection as a secondary procedure was performed in eleven cases (79%). The mean pre- and postoperative FDI was 87.6±6.3 and 95.4±5.2 with a significant advance for symmetry (p < 0.001). The pre- and postoperative VAS for asymmetry was 7.2±1.7 and 3.8±2.4 respectively, with a significant improvement (p = 0.002). CONCLUSION: Our integrated approach using orthognathic surgery, facial contouring surgery and subsequent fat injection is satisfactory and obtain significant improvement of the facial deformity considering the complexity of HFM.

Monobloc Frontofacial or Le Fort III Distraction Osteogenesis in Syndromic Craniosynostosis: Three-Dimensional Evaluation of Treatment Outcome and the Need for Central Distraction.

BACKGROUND: The objectives of this study were to investigate the treatment effect, morphology, and volumetric outcomes of monobloc frontofacial or Le Fort III distraction osteogenesis in syndromic craniosynostosis by 3-dimensional evaluation. MATERIALS AND METHODS: Nine consecutive patients underwent monobloc frontofacial or Le Fort III distraction during 2003 to 2012 were included and evaluated. The patient's evaluation is a minimum of a 4-year follow-up. Pretreatment, post-treatment advancement, and relapse were quantified. The changes in intracranial volume, upper airway volume, globe protrusion, advancement at bilateral malar eminence, and central face were calculated from computerized tomography before and after treatment. RESULTS: After distraction, the intracranial volume was increased by 16.4% in average, and the upper airway volume increased by 64.1%. Orbital protrusion improved by 9.9 mm in the left eye and 10.5 mm in the right eye in comparison to the preoperative status. Bilateral malar eminences advancement was greater than the dorsum advancement by 7.1 mm. CONCLUSION: The external distraction osteogenesis device caused significant technical difficulties with advancement of the midface in growing bones. The central midface did not advance as hoped for. This finding may suggest a need for modification in the distraction device in order to improve the central facial distraction vector.

Mandibular Contouring During Orthognathic Surgery Using the Modified Hunsuck Technique.

Square face or prominent mandibular angle is a major concern in Asian women. In class III patients, mandibular setback may lead to a wider lower face that is not preferred in Asian culture. In order to achieve better aesthetic outcomes, simultaneous mandibular contouring to reduce the width of the lower face is required for some patients. This article details the authors' procedures modified from Hunsuck techniques of sagittal split osteotomy. This modified Hunsuck technique provides an alternative option to obtain a desirable mandibular outline. The long-term stability is also comparable to traditional methods.

Simultaneous maxillo-mandibular distraction in early adolescence as a single treatment modality for durable correction of type II unilateral hemifacial microsomia: Follow-up till completion of growth.

BACKGROUND: Timing of surgical intervention in hemifacial microsomia (HFM) is controversial. Although mandibular osteodistraction in childhood for HFM is popular, recent data for single-stage distraction in growing HFM patients demonstrated long-term relapse. Literature suggests that adolescents in the late mixed dentition age or permanent dentition age (11-16-year-old) had more stable outcomes post-distraction than younger children. We present favorable experience using single-treatment simultaneous maxillo-mandibular distraction in early adolescent Pruzansky-Kaban type II HFM patients. METHODS: This was a retrospective longitudinal study of seven consecutive type IIa/b HFM growing patients (12-16-year-old) treated with simultaneous maxillo-mandibular distraction. Oral commissure cant was photographically measured preoperatively and at 6 months and annually ranging 3-7 years post-distraction. Ramus height and chin deviation were measured from radiographs done preoperatively and at distractor-removal, 1 year, 2 years, and 4 years post-distraction. RESULTS: Average age at osteodistraction and at latest follow-up was 13.7 and 18.6 years, respectively. Improvement was significant (p < 0.05) and sustained for mean oral commissure cant (5.1°-0.41°), mean ramus height ratio (0.59-0.86), and average chin deviation (15.9 mm-1.2 mm). Two subjects had mandibular branch palsy and one had mild pin-tract infection - all resolved. All were satisfied with their facial appearance. CONCLUSION: We have demonstrated good lasting outcomes at completion of growth with single-stage simultaneous maxillo-mandibular distraction for type II HFM adolescents in the late mixed-dentition or older age, and advocate this as an alternative to osteodistraction or orthognathic surgery upon skeletal maturity.

Effects of proximal grooves and abutment height on the resistance of resin-cemented crowns in teeth with inadequate resistance: An in vitro study.

BACKGROUND: The resistance form is a key factor for a successful crown fabrication. This in vitro study evaluates the effects of proximal grooves and abutment height on the resistance of single cast crowns in molars with inadequate resistance. METHODS: Sixty extracted human molars were prepared to possess 20° of total occlusal convergence for single crown fabrication. All of the prepared teeth were divided into six groups and prepared according to three axial heights (2, 3, and 4 mm) with or without preparing a pair of proximal grooves. Alloy metal copings of 5% titanium were casted and cemented. A self-adhesive modified-resin cement was used for cementation. A lateral dislodgement test was performed with an increasing external force applied at a 45° angulation on a universal testing machine. The force required to dislodge the crown from the tooth or to break the core was recorded. RESULTS: Proximal grooves increased the dislodgement resistance in groups with an abutment height of 4 mm, whereas adding grooves made no significant differences in resistance in groups with abutment heights of 2 and 3 mm. The 2 mm groups exhibited worse performance than the other groups, whether they had proximal grooves or not. CONCLUSION: An abutment height of 3 mm provided adequate resistance for single cast crowns when self-adhesive modified-resin cement was used. Preparing a pair of proximal grooves on abutments shorter than 4 mm had no significant influence on the resistance.

The Effect of early physiotherapy on the recovery of mandibular function after orthognathic surgery for Class III correction: part I--jaw-motion analysis.

The aim of this prospective study was to compare the mandibular range of motion in Class III patients with and without early physiotherapy after orthognathic surgery (OGS). This study consisted of 63 Class III patients who underwent 2-jaw OGS. The experimental group comprised 31 patients who received early systematic physical rehabilitation. The control group consisted of 32 patients who did not have physical rehabilitation. Twelve variables of 3-dimensional (3D) jaw-motion analysis (JMA) were recorded before surgery (T1) and 6 weeks (T2) and 6 months (T3) after surgery. A 2-sample t test was conducted to compare the JMA results between the two groups at different time points. At T2, the JMA data were measured to be 77.5%-145.7% of presurgical values in the experimental group, and 60.3%-90.6% in the control group. At T3, the measurements were 112.2%-179.2% of presurgical values in the experimental group, and 77.6%-157.2% in the control group. The patients in the experimental group exhibited more favorable recovery than did those in the control group, from T1 to T2 and T1 to T3. However, after termination of physiotherapy, no significant difference in the extent of recovery was observed between groups up to 6 months after OGS.