Orthognathic Surgery In Skeletal Class Research Articles

Orthognathic Surgery in Skeletal Class l Patient with Facial Asymmetry

The purpose of this case report was to describe the considerations in surgical orthodontic treatment of a patient with skeletal Class I malocclusion and facial asymmetry. A 22-year-old male presented with a chief complaint of facial asymmetry. Clinical examination showed severe facial asymmetry to the right side at his chin point. Also he showed lip canting and straight facial profile. Intraorally, he exhibited posterior crossbite in the right side with severe mandibular dental midline deviation to the right. After presurgical orthodontic treatment with dental decompensation was done, sagittal split ramus osteotomy (SSRO) with mandibular body shaving was done to correct the mandibular asymmetry. After orthodontic treatment, posterior crossbite and midline of the dentition was corrected, and asymmetry of the mandible was improved. For the patient with facial asymmetry, it is critical to eliminate dental compensation orthodontically and to move the teeth to their proper positions to avoid relapse and obtain stability.

A New Approach to Set the Absolute Midsagittal Plane of the Mandible Using a Similarity Index in Skeletal Class III Patients with Facial Asymmetry

This study sought to test the feasibility of a newly developed plane called computed modified absolute mandibular midsagittal plane (cmAMP) based on the similarity index (SI) for evaluating the stereoscopical symmetry of the mandible by comparison with other proposed midsagittal planes. This study involved 29 adult patients (15 men, 14 women; average age, 23.1 ± 6.9 years) with skeletal Class III facial asymmetry who underwent bimaxillary orthognathic surgery. Using cone-beam computed tomography images taken before and 1 year after surgery, cmAMP with the highest SI value between the two anterior segments of the hemi-mandible was set by a computer algorithm. Results show that the SI using cmAMP had the highest value (0.83 ± 0.04) before surgery compared to the other midsagittal planes, and was not significantly different from the SI (0.80 ± 0.05) using a facial midsagittal plane (MSP) after surgery. The distance (1.15 ± 0.74 mm) and angle (2.02 ± 0.82°) between MSP and cmAMP after surgery were significantly smaller than those between MSP and other midsagittal planes. In conclusion, the cmAMP plane best matches the two anterior segments of hemi-mandible symmetrically and is the closest to MSP after orthognathic surgery in skeletal Class III patients with facial asymmetry.

Effects of different nose types on class II treatments for female patients

BackgroundThe aim of this study was to evaluate the effect of different nose types on the perception of facial aesthetics following camouflage treatment and orthognathic surgery for skeletal class II female patients.MethodsA pre-treatment profile photograph of a skeletal class II adult patient was selected from the department archive. Two constructed photographs were created to represent orthognathic surgery and camouflage treatments with the aid of computer software. A total of 18 constructed images was composed using three profiles (pre-treatment, post-camouflage, and post-orthognathic surgery) and six nose types. These photographs were shown to the three groups (orthodontists, plastic surgeons, and lay people), and they were asked to assign an attractiveness score to each photo ranging from 0 to 100, with 0 indicating the least attractive and 100 indicating the most attractive.ResultsFor the convex nose profiles, anterior movement of the mandible obtained by orthognathic surgery did not result in a significant change in the scores given by the lay people. When surgical or camouflage treatment was not implemented and, instead, just rhinoplasty was performed for these profiles, there was a significant increase in the aesthetic scores given by all groups. For the straight nose profiles, orthognathic surgery increased the attractiveness scores given by all groups. Furthermore, for all the profiles, extraction treatment did not affect the aesthetic scores given by any of the groups (P > 0.05).ConclusionsThe lay people perceived that having a convex-bridged nose was a bigger problem than having a retrognathic profile. Overall, in terms of skeletal and dental orthodontic treatments, nose shape should be considered during the treatment planning process.

Orthognathic Treatment Using Combination Surgery (Unilateral Sagittal Ramus Osteotomy and Unilateral Intraoral Vertical Ramus Osteotomy) for Skeletal Class III Malocclusion Patient with Facial Asymmetry

This case report describes a successful orthognathic treatment using a combination surgery; unilateral sagittal ramus osteotomy (USSRO) and unilateral intraoral vertical ramus osteotomy (UIVRO). A 23-year-old male patient showing skeletal class III malocclusion with mandibular asymmetry visited our orthodontic department. Characteristics of his facial asymmetry was translation of the mandibular dentition to the left side, without yawing or canting of both jaws. After pre-surgical orthodontic treatment, orthognathic surgery with LeFort I osteotomy in the maxilla and combination surgery in the mandible was performed (USSRO on non-deviation side and UIVRO on deviation side). After 18-month of overall treatment, facial appearance and malocclusion were improved. The combination surgery (USSRO + UIVRO) could be a predictable and better treatment option that overcome the limitations of conventional orthognathic surgery for skeletal class III malocclusion with asymmetry.

Three-dimensional alterations in pharyngeal airspace, soft palate, and hyoid bone of class II and class III patients submitted to bimaxillary orthognathic surgery: A retrospective study

IntroductionThe aim of this retrospective study was to evaluate changes in pharyngeal airway space (PAS), soft palate, and hyoid bone position after bimaxillary orthognathic surgery in skeletal Class II and Class III patients. MethodsPatients were divided into Group 1: Class III patients who underwent maxillary osteotomies and mandibular setback surgery (N = 43); and Group 2: Class II patients who underwent maxillomandibular advancement surgery (N = 36). Cone beam computed tomography (CBCT) images were acquired one month before and six to eight months after orthognathic surgery. PAS area, volume and minimum axial area (MAA), soft-palate morphology, and hyoid bone position measurements obtained before and after orthognathic surgery were compared using the Gamma family test (p ≤ 0.10). ResultsIn Class II group the maxillomandibular advancement surgery significantly increased the PAS area, volume, and MAA and significantly affected hyoid bone position and soft-palate morphology. In Class III group, maxillary osteotomies and mandibular setback also showed increase in PAS area, however without statistically significant values for most of the evaluated measurements. ConclusionThe results of the present study indicate that PAS and related structures are expected to be improved in Class II patients submitted to bimaxillary surgery, and they are not negatively affected by bimaxillary surgery in Class III patients.

Short-term changes in muscle activity and jaw movement patterns after orthognathic surgery in skeletal Class III patients with facial asymmetry.

ObjectiveTo evaluate the short-term changes in masticatory muscle activity and mandibular movement patterns after orthognathic surgery in skeletal Class III patients with facial asymmetry.MethodsTwenty-seven skeletal Class III adult patients were divided into two groups based on the degree of facial asymmetry: the experimental group (n = 17 [11 male and 6 female]; menton deviation ≥ 4 mm) and control group (n = 10 [4 male and 6 female]; menton deviation < 1.6 mm). Cephalography, electromyography (EMG) for the anterior temporalis (TA) and masseter muscles (MM), and mandibular movement (range of motion [ROM] and average chewing pattern [ACP]) were evaluated before (T0) and 7 to 8 months (T1) after the surgery.ResultsThere were no significant postoperative changes in the EMG potentials of the TA and MM in both groups, except in the anterior cotton roll biting test, in which the masticatory muscle activity had changed into an MM-dominant pattern postoperatively in both groups. In the experimental group, the amount of maximum opening, protrusion, and lateral excursion to the non-deviated side were significantly decreased. The turning point tended to be shorter and significantly moved medially during chewing in the non-deviated side in the experimental group.ConclusionsIn skeletal Class III patients with facial asymmetry, the EMG activity characteristics recovered to presurgical levels within 7 to 8 months after the surgery. Correction of the asymmetry caused limitation in jaw movement in terms of both ROM and ACP on the non-deviated side.

Changes in Cervical Lordosis After Orthognathic Surgery in Skeletal Class III Patients.

The purpose of this study was to evaluate cervical lordosis and head posture changes using lateral cephalographs after bimaxillary orthognathic surgery for mandibular prognatism by null hypothesis. Twenty-five patients with skeletal class III dentofacial deformities (10 men, 15 women; mean age, 29.28 ± 8.23 years; range 18-48 years) were included in this prospective clinical study. Lateral cephalographs were taken in natural head position (NHP) 2 weeks before and 6 months after orthognathic surgery. The reproducibility of the radiographer's technique of taking radiographs in NHP was investigated using a photographic method and found to be acceptable. All measurements for cervical lordosis (CV1/CV2; CV3/CV7; CV1/CV7), head posture (NSL/OPT; NSL/VER), and other cephalometric values (NSL/Go-Gn; NSL/OCL; Overjet) were repeated 3 times by the same blinded investigator at 2-week intervals and the average values of the 3 measurements were calculated to use in statistical analysis. Intraclass correlation coefficients (ICC) ranged between 0.996 and 1.000, demonstrating a high reliability of the measures. Statistically significant differences were found for CV3/CV7 (P = 0.006) and CV1/CV7 (P = 0.005) and no significant differences were identified in head posture for both cranio-cervical and cranio-vertical angles. The null hypothesis was rejected. Orthognathic surgery resulted in significant cervical lordosis extension, and a tendency for head extension could also be observed.

The structural changes of pharyngeal airway contributing to snoring after orthognathic surgery in skeletal class III patients

BackgroundTwo-jaw surgery including mandibular and maxillary backward movement procedures are commonly performed to correct class III malocclusion. Bimaxillary surgery can reposition the maxillofacial bone together with soft tissue, such as the soft palate and the tongue base. We analyzed changes of pharyngeal airway narrowing to ascertain clinical correlations with the prevalence of snoring after two-jaw surgery.MethodsA prospective clinical study was designed including a survey on snoring and three-dimensional (3D) computed tomography (CT) in class III malocclusion subjects before and after bimaxillary surgery. We conducted an analysis on changes of the posterior pharyngeal space find out clinical correlations with the prevalence of snoring.ResultsAmong 67 subjects, 12 subjects complained about snoring 5 weeks after the surgical correction, and examining the 12 subjects after 6 months, 6 patients complained about the snoring. The current findings demonstrated the attenuation of the largest transverse width (LTW), anteroposterior length (APL), and cross-sectional area (CSA) following bimaxillary surgery given to class III malocclusion patients, particularly at the retropalatal level. The average distance of maxillary posterior movements were measured to be relatively higher (horizontal distance 3.9 mm, vertical distance 2.6 mm) in case of new snorers.ConclusionsThis study found that bimaxillary surgery could lead to the narrowing of upper airway at the retropalatal or retroglossal level as well as triggering snoring in subjects with class III malocclusion. Based on the current clinical findings, we also found that upper airway narrowing at retropalatal level may contribute to increasing the probability of snoring and that polysonography may need to be performed before orthognathic surgery in subjects with class III malocclusion.

Abstract: The Change of Posterior Pharyngeal Space after Counter Clock-wise Rotational Orthognathic Surgery Based on Cephalometry

INTRODUCTION: Maxillomandibular advancement (MMA) is an orthognathic surgical procedure that has been used to manage OSA in individuals who are noncompliant with CPAP therapy.1 MMA is a site-specific procedure, performed for the purpose of creating an enlarged posterior airway space at multiple anatomic levels, including the nasopharynx, oropharynx, and hypopharynx.2 MMA has been shown to significantly improve OSA, with reported short term success rates ranging from 75% to 100%.3–5 This prospective investigation describes the functional and aesthetic outcomes after the counter clock wise rotational orthognathic surgery in skeletal class II patients with the obstructive sleep apnea based on pre and postoperative polysomnography and cephalometry. MATERIALS AND METHODS: This retrospective study investigated the surgical outcome of 12 patients who suffered from obstructive sleep apnea following the counter clock wise rotational orthognathic surgery in terms of functional and aesthetic outcomes. The patients included in this study were skeletal class II patients who underwent orthognathic surgery between March, 2013 and December, 2014 at the Seoul Asan Medical Center, University Medical Center for tertiary care. The pharyngeal airway assessment was done through polysomnography and cephalometric posterior airway analysis using PRL–PSP, PRL–PTO and PRL–E distances. RESULTS: The follow-up period ranged from 10 to 36 months (average, 20.5 months). The average age of the patients was 28.5 years, with 9 male and 11 female patients. Compared to preoperative results (mean preop distance of PRL–PSP: 19.97, PRL–PTO: 18.68, PRL–E: 16.2), PRL–PSP, PRL–PTO and PRL–E distances were increased statistically significant in immediate postoperative cephalometry. (p<0.005) (mean immediate postop distance of PRL–PSP: 23.1, PRL–PTO: 22.9, PRL–E: 18.6). The results were maintained 6 months after the surgery(mean distant postop distance of PRL–PSP: 22.2, PRL–PTO: 22.5, PRL–E: 18.0). There was no significant change in PRL–PSP, PRL–PTO and PRL–E distances.(p>0.05). CONCLUSION: The change of the posterior pharyngeal space in counter clock-wise rotational orthognathic surgery without maxilla advancement for the correction of obstructive sleep apnea is presented. Our findings indicate that this approach can lengthen the posterior pharyngeal space effectively. With considered application, this novel approach could be an alternative to standard approaches in the correction of obstructive sleep apnea using orthognathic surgery. DISCLOSURES/FINANCIAL SUPPORT:None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript. REFERENCES: 1. Fernández-Ferrer L, Montiel-Company JM, Pinho T, Almerich-Silla JM, Bellot-Arcís C. Effects of mandibular setback surgery on upper airway dimensions and their influence on obstructive sleep apnoea - a systematic review. J Craniomaxillofac Surg. 2015;43:248–53. 2. Demetriades N, Chang DJ, Laskarides C, Papageorge M. Effects of mandibular retropositioning, with or without maxillary advancement, on the oro-naso-pharyngeal airway and development of sleep-related breathing disorders. J Oral Maxillofac Surg. 2010;68:2431–6. 3. Gonçalves JR, Gomes LC, Vianna AP, Rodrigues DB, Gonçalves DA, Wolford LM. Airway space changes after maxillomandibular counterclockwise rotation and mandibular advancement with TMJ Concepts® total joint prostheses: three-dimensional assessment. Int J Oral Maxillofac Surg. 2013;42:1014–22. 4. Hatab NA, Konstantinović VS, Mudrak JK. Pharyngeal airway changes after mono- and bimaxillary surgery in skeletal class III patients: Cone-beam computed tomography evaluation. J Craniomaxillofac Surg. 2015;43:491–6. 5. Jakobsone G, Stenvik A, Espeland L. The effect of maxillary advancement and impaction on the upper airway after bimaxillary surgery to correct Class III malocclusion. Am J Orthod Dentofacial Orthop. 2011;139:e369-76.

Kinematic analysis of mandibular motion before and after orthognathic surgery for skeletal Class III malocclusion: A pilot study

Objectives: The aim of the study was to detect the changes in 3D mandibular motion after orthognathic surgery for skeletal Class III malocclusion.Method: Using a 3D motion analyzer, free mandibular border movements were recorded in nine patients successfully treated for skeletal Class III malocclusion and in nine patients scheduled for orthognathic surgery. Data were compared using Mann–Whitney non-parametric U-test.Results: The results showed no differences between the groups in the total amount of mouth opening, protrusion, and in lateral excursions, but the percentage of mandibular movement explained by condylar translation was significantly increased after surgery (20% vs. 23.6%). During opening, the post-surgery patients showed a more symmetrical mandibular interincisal point and condylar path than pre-surgery patients (p < 0.01).Discussion: Patients treated with orthognathic surgery for skeletal Class III malocclusion recover a good and symmetric temporomandibular joint function.

Three-dimensional evaluation of the pharyngeal airway using cone-beam computed tomography following bimaxillary orthognathic surgery in skeletal class III patients.

The study aims to evaluate the pharyngeal airway space (PAS) following bimaxillary surgery in skeletal class III patients and to compare the changes in PAS between genders using cone-beam computed tomography (CBCT). In all, 38 patients (16 male and 22 female) with skeletal class III malocclusion underwent bimaxillary surgery. CBCT scans were acquired approximately 1month before surgery, 3months after surgery, and 6months after surgery. The oropharyngeal volume and the minimum cross-sectional area (CSA) were characterized using the InVivoDental imaging software package at each time point. The volume and minimum CSA decreased significantly postoperatively, which was maintained until 6months postoperatively (p<0.01). The location of the minimum CSA tended to move into the retropalatal and retroglossal areas postoperatively. A strong correlation between volume and minimum CSA was found. The amount of mandibular setback was not correlated with the change in the airway. By gender, significant decreases in both the volume and minimum CSA were found in females (p<0.05) but not in males. Bimaxillary surgery significantly affects PAS. Gender differences should also be considered when considering changes in PAS. An awareness of the effects of bimaxillary setback surgery on the airway should be considered when implementing an orthognathic treatment plan.

Prediction of pharyngeal airway changes in skeletal class III deformity patients after orthognathic surgery

BackgroundPharyngeal airway changes after orthognathic surgery in skeletal class III patients have been of concern because of the effects on breathing function. ObjectivesThe aim of this study was to evaluate the pharyngeal airway changes in patients with skeletal class III deformity who underwent orthognathic surgery. Materials and methodsThirty-two patients who underwent orthognathic surgery at Oral and Maxillofacial Surgery Department, Mahidol University, Thailand were included in this study. The subjects were divided in two groups: group 1 underwent mandibular setback (19 patients) and group 2 underwent bimaxillary surgery (13 patients). Lateral cephalogram was taken 3 times: preoperation (T0), immediate postoperation (T1) and 6 months postoperation (T2). ResultsThe mean amount mandibular setback for group 1 and group 2 were 7.3mm and 6.5mm, respectively. The mandibular setback group demonstrated significant decrease in pharyngeal airway dimension at both retropalatal and retrolingual level as well as oropharyngeal area. On the other hand, the bimaxillary surgery group showed no significant decrease but increase at retropalatal level. The linear regression analysis suggested that the change in C3-B distance can be a predictor for pharyngeal airway change in mandibular setback group (r=0.789, p<0.01). ConclusionBimaxillary surgery clearly demonstrated better control on the pharyngeal airway than mandibular setback group in skeletal class III patients.

Differences in three-dimensional soft tissue changes after upper, lower, or both jaw orthognathic surgery in skeletal class III patients

The decision is not always straightforward as to which orthognathic procedure is best for a good aesthetic result; three-dimensional imaging has brought new insight into this topic. The aim of this prospective study was to verify objectively whether postoperative changes occur within those regions not directly affected by surgical movements of the underlying jaw bones. The study included 83 young adults with skeletal class III deformities. They were classified into three groups according to the type of surgery: bilateral sagittal split osteotomy set-back of the mandible (BSSO), Le Fort I advancement of the maxilla, or a combination of both. Pre- and postoperative optical scans were registered as regional best-fits on the areas of the foreheads and both orbits. The shell to shell differences were measured and the average distances between the observed regions were calculated. As expected, changes were greatest in the regions where the underlying bones had been moved, but regardless of the operation performed, changes were found over the whole face. Changes in the nose, cheek, and upper lip regions in the BSSO group and in the lower lip and chin region in the Le Fort I group confirmed the concept of the facial soft tissue mask acting as one unit.

Evaluation of recovery in lip closing pressure and occlusal force and contact area after orthognathic surgery

PurposeThe purpose of this study was to evaluate the relationship between lip closing force, occlusal contact area and occlusal force after orthognathic surgery in skeletal Class III patients. Subjects and methodsThe subjects consisted of 54 patients (28 female and 26 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces, occlusal contact area and occlusal force were measured pre-operatively, 6 months and 1 year post-operative. ResultsMaximum and minimum lip closing forces, occlusal contact area and occlusal force increased with time after surgery, however a significant increase was not found in the occlusal contact area in women. In increased ratio (6 months/pre-operative and 1 year/pre-operative), the maximum lip closing force was significantly correlated with the occlusal contact area (P < 0.0001). ConclusionsThis study suggested that orthognathic surgery could improve the occlusal force, contact area and lip closing force, and an increase ratio in maximum lip closing force was associated with an increased ratio in occlusal contact area.

The time-course change in the lip closing force in Class III malocclusion after orthognathic surgery

ObjectivesThe purpose of this study was to examine the changes with time in lip pressure after orthognathic surgery for skeletal Class III patients. Study designThe subjects consisted of 63 patients (32 female and 31 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces were measured with Lip De Cum®. The changes with time were compared statistically. ResultsThe maximum and minimum lip closing force increased time-dependently in men and women after surgery and there were significant differences between men and women with changes with time in the maximum lip closing force (p = 0.0086) and the minimum lip closing force (p = 0.0302). After 1 year, the Class III group maximum lip closing force was significantly smaller than the control group in both men (p < 0.0001) and women (p < 0.0001). ConclusionsThis study suggests that there was significant difference in over time in the lip closing force between men and women in Class III patients. Although the maximum lip closing force increased with time, it did not reach the level of the control group after 1 year.

Changes in electric activity of masseter and anterior temporalis muscles before and after orthognathic surgery in skeletal class III patients

The purpose of this study was to evaluate, through clinical and electromyographic (EMG) assessments, the electric activity of masseter muscle and anterior temporalis muscles during clenching, before and after orthodontic treatment and mandibular setback, with or without LeFort I osteotomy, for correction of mandibular excess. Seventeen adult patients (10 males, 7 females, mean age: 22.5 ± 2.4 years) were recruited for this study. All patients received orthodontic treatment and surgical corrections. EMG recordings were obtained from 4 channels of the 8-channel electromyograph FREELY (DeGoetzen spa, Olgiate Olona, VA, Italy). A significant difference was found in the value of activity index at T0-T1 (33% T0, 1% T1) (P < .05), of asymmetry index at T0-T1 (21% T0, 4% T1) (P < .05), and of torque index at T0-T1 (24% T0, 5% T1) (P < .05). The evaluation of EMG activity after surgery may be considered a sign of good adaptation of the neuromuscular system to the new occlusal condition and a good method for detecting nonresponding patients who might require further treatment.

Frontal soft tissue analysis using a 3 dimensional camera following two-jaw rotational orthognathic surgery in skeletal class III patients

Although two dimensional cephalometry is the standard method for analyzing the results of orthognathic surgery, it has potential limits in frontal soft tissue analysis. We have utilized a 3 dimensional camera to examine changes in soft tissue landmarks in patients with skeletal class III dentofacial deformity who underwent two-jaw rotational setback surgery.We assessed 25 consecutive Asian patients (mean age, 22 years; range, 17–32 years) with skeletal class III dentofacial deformities who underwent two-jaw rotational surgery without maxillary advancement. Using a 3D camera, we analyzed changes in facial proportions, including vertical and horizontal dimensions, facial surface areas, nose profile, lip contour, and soft tissue cheek convexity, as well as landmarks related to facial symmetry.The average mandibular setback was 10.7 mm (range: 5–17 mm). The average SNA changed from 77.4° to 77.8°, the average SNB from 89.2° to 81.1°, and the average occlusal plane from 8.7° to 11.4°. The mid third vertical dimension changed from 58.8 mm to 57.8 mm (p = 0.059), and the lower third vertical dimension changed from 70.4 mm to 68.2 mm (p = 0.0006). The average bigonial width decreased from 113.5 mm to 109.2 mm (p = 0.0028), the alar width increased from 34.7 mm to 36.1 mm (p-value = 0.0002), and lip length was unchanged. Mean mid and lower facial surface areas decreased significantly, from 171.8 cm2 to 166.2 cm2 (p = 0.026) and from 71.23 cm2 to 61.9 cm2 (p < 0.0001), respectively. Cheek convexity increased significantly, from 171.8° to 155.9° (p = 0.0007).The 3D camera was effective in frontal soft tissue analysis for orthognathic surgery, and enabled quantitative analysis of changes in frontal soft tissue landmarks and facial proportions that were not possible with conventional 2D cephalometric analysis.

Skeletal and Dental Variables Related to the Stability of Orthognathic Surgery in Skeletal Class III Malocclusion With a Surgery-First Approach

The objectives of the study were to identify the parameters related to skeletal stability after orthognathic surgery in skeletal Class III malocclusion using a surgery-first approach and to analyze the factors correlated with surgical relapse. Forty-five consecutive patients were included. Serial cephalometric radiographs were traced and superimposed to investigate surgical stability at the initial examination, 1 week postoperatively, and after orthodontic debonding (12.22 mo after surgery). Patient grouping was based on the amount of horizontal relapse at the innermost point of the contour of the mandible between the incisor tooth and the bony chin, the B point (less stable group, n = 15; highly stable group, n = 18). Parameters, such as presurgical skeletal and dental variables, the amount of surgical setback, and total treatment duration, were compared between groups and analyzed for correlations with surgical stability. The mean setback at the innermost point of the contour of the mandible between the incisor tooth and the bony chin was 11.19 mm, and the mean relapse rate was 12.46%. The amount of surgical setback, overbite (positive values), overjet, depth of the curve of Spee, and lower anterior facial height showed statistically significant differences between groups. The amount of surgical setback, overbite (positive values), overjet, and depth of the curve of Spee showed statistically significant correlations with the amount of relapse. Skeletal relapse of the mandible increased significantly as the overbite increased. The factors for instability in the surgery-first approach include a larger overbite, a deeper curve of Spee, a greater negative overjet, and a greater mandibular setback. The initial overbite may be an indicator to predict possible skeletal relapse of mandibular setback.

Skeletal and dental relapses after skeletal class III deformity correction surgery: single-jaw versus double-jaw procedures

In this prospective comparative study, we looked at the postoperative dental and skeletal relapses in patients undergoing orthognathic surgery for skeletal class III deformity. The surgical interventions were single-jaw versus double-jaw procedures. Twenty-four adult patients with skeletal class III deformity presented with functional and esthetic problems. Patients were randomized to receive single- or double-jaw corrective surgery. The assessment of outcome was by lateral cephalograms taken at different intervals and postoperative complications. At 1 year after surgery, no significant correlation was identified between surgical advancement and relapse regarding maxillary stability. The single-jaw procedure cohort had a significantly greater horizontal mandibular skeletal relapse. No differences were noted when examining the mandibular vertical stability. None of the patients reported any acute local neurology. Single-jaw procedure may lead to less stability, leading to skeletal relapse, than double-jaw procedure. A higher evidence-based study and larger cohort is required to prove this.

Changes in the lip closing force of patients with Class III malocclusion before and after orthognathic surgery

The purpose of this study was to examine the changes in lip pressure before and after orthognathic surgery for skeletal Class III patients. The subject groups were 32 female and 31 male patients diagnosed with mandibular prognathism and/or maxillary retrognathism who underwent orthognathic surgery. Control groups consisted of 20 women and 20 men with normal occlusion without dento-alveolar deformity. Maximum and minimum lip closing force was measured with Lip De Cum® for the control groups and subject groups preoperatively and 6 months postoperatively. The difference between the pre- and postoperative values of the groups was examined statistically. The maximum lip closing force in men was significantly larger than that in women in both the preoperative Class III group (p=0.0330) and the control group (p=0.0097). The preoperative Class III group was significantly smaller than the control group in maximum lip closing force in both men (p<0.0001) and women (p<0.0001). The postoperative maximum lip closing force was significantly larger than the preoperative value in both men (p=0.0037) and women (p=0.0273) in the Class III group. This study suggested that the maximum lip closing force increases after orthognathic surgery in Class III patients.