Hyoung-Seon Baik

Facial soft-tissue changes in skeletal Class III orthognathic surgery patients analyzed with 3-dimensional laser scanning.

INTRODUCTION Patients undergoing orthognathic surgery show considerable changes in both hard and soft tissues. The purpose of this study was to use a 3-dimensional (3D) laser scanner to evaluate the soft-tissue changes after the correction of skeletal Class III malocclusions with orthognathic surgery. METHODS The subjects consisted of 20 Korean patients with skeletal Class III malocclusion who underwent LeFort I osteotomy with maxillary advancement and posterior nasal spine impaction, along with bilateral intraoral vertical ramus osteotomy for mandibular setback. Ten patients (group 1) had 2-jaw surgery with genioplasty, and the other 10 (group 2) had 2-jaw surgery without genioplasty. Three-dimensional images of the patients were acquired with a 3D laser scanner. The ratios of soft-tissue changes to hard-tissue movements were analyzed and compared between the 2 groups. In addition, the changes in the soft-tissue landmarks in the 3D coordinates and the 3D linear, angular, and proportional changes were measured preoperatively and postoperatively, and compared. RESULTS There was no significant difference between the groups in the horizontal ratios of the soft-tissue to hard-tissue changes. In both groups, the ratios of the horizontal changes in the paranasal area were higher than in the subnasal area. There were more changes in the subalar area than in the supracommissural area, and more changes in the chin and labiomental areas than in the subcommissural area. Ala moved anterolaterally, and cheilion moved posteroinferiorly. The distance between upper-lip point and cheilion increased significantly (P <0.05). In the 3D angles, transverse nasal prominence and transverse upper lip prominence increased significantly (P <0.05). CONCLUSIONS The 3D analysis in this study can be used to estimate the soft-tissue changes in Class III patients who undergo orthognathic surgery.

Three-dimensional computed tomography analysis of mandibular morphology in patients with facial asymmetry and mandibular prognathism

INTRODUCTION The purpose of this study was to investigate the dimensional changes in each skeletal unit in the mandibles of patients with facial asymmetry and mandibular prognathism. METHODS The patients consisted of 50 adults with mandibular prognathism, divided into the symmetry group (n = 20) and the asymmetry group (n = 30) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with a spiral computed tomography scanner. Landmarks were designated on the reconstructed 3-dimensional surface models. The lines to represent condylar, coronoid, angular, body, and chin units were used. Ramal and body volumes were measured in the hemi-mandibles. RESULTS In the asymmetry group, condylar and body unit lengths were significantly longer, and coronoid unit length was significantly shorter on the nondeviated side than on the deviated side (P <0.01). Angular and chin unit lengths were not significantly different between the 2 sides (P >0.05). Ramal volume was significantly greater on the nondeviated side (P <0.01), but body volume was not significantly different between the 2 sides (P >0.05). CONCLUSIONS Both condylar and body units appeared to contribute to mandibular asymmetry, with a more central role of the condylar unit.

Morphological characteristics of the symphyseal region in adult skeletal Class III crossbite and openbite malocclusions.

OBJECTIVE To evaluate the relationship of the morphological characteristics of the symphyseal region of adult Class III malocclusion to the differences in overjet and overbite. MATERIALS AND METHODS The basal and symphyseal widths along with the alveolar and symphyseal heights were evaluated using data from the lateral cephalograms of Korean adult male skeletal Class III, divided into crossbite (n = 28) and openbite (n = 41) groups. Korean male normal occlusion samples (n = 32) were used as controls. RESULTS The width of the symphyseal region including the basal width, point B width, Id width, symphyseal thickness, and pogonion width were similar in adult Class III crossbite and normal occlusion groups, but significantly less in the adult Class III openbite group (P < .001). The alveolar height was similar in the adult Class III crossbite and control groups, but significantly less in the adult Class III openbite group (P < .05). However, the symphyseal height was similar in all three groups. CONCLUSIONS An openbite, rather than a negative overjet, is the major factor influencing the symphyseal morphology in an adult Class III malocclusion.

Morphologic relationship between the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism

INTRODUCTION This study was conducted to measure the dimensional changes in the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism, and to examine the morphologic relationship between asymmetries of the cranial base and the mandible. METHODS The patients were 60 adults with mandibular prognathism, divided into a symmetry group (menton deviation, <2 mm; n = 30) and an asymmetry group (menton deviation, >4 mm; n = 30) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with a spiral scanner. Landmarks were designated on the reconstructed 3-dimensional surface models. Linear, angular, and volumetric measurements of the cranial base and mandibular variables were made. RESULTS In the asymmetry group, the hemi-base, anterior cranial base, and middle cranial base volumes were significantly larger (P <0.01), and crista galli to sphenoid, sphenoid to petrous ridge, anterior clinoid process to petrous ridge, and vomer to petrous ridge lengths were significantly longer (P <0.05) on the nondeviated side than on the deviated side. Menton deviation was significantly correlated with the difference in hemi-base volume, and ramal volume was significantly correlated with the difference in hemi-base and middle cranial base volumes between the nondeviated and deviated sides (P <0.05). CONCLUSIONS In patients with facial asymmetry and mandibular prognathism, cranial base volume increased on the nondeviated side and was also correlated with mandibular asymmetry.

Stability of Pre-Orthodontic Orthognathic Surgery Using Intraoral Vertical Ramus Osteotomy Versus Conventional Treatment

PURPOSE Postoperative skeletal and dental changes were evaluated in patients with mandibular prognathism who underwent mandibular setback surgery using an intraoral vertical ramus osteotomy (IVRO) with and without presurgical orthodontic treatment. MATERIAL AND METHODS This retrospective cohort study included consecutive patients with skeletal Class III malocclusions who underwent IVRO. Patients treated with pre-orthodontic orthognathic surgery (POGS) were compared with patients treated with conventional surgery (CS) with presurgical orthodontics (control) using lateral cephalograms (taken preoperatively, 7 days postoperatively, and 12 months postoperatively). Predictor (group and timing), outcome (cephalometric measurements over time), and other (ie, baseline characteristics) variables were evaluated to determine the differences in postoperative horizontal and vertical positional changes of the mandible, such as point B. Baseline demographics were similar between the groups (N = 37; CS group, n = 17; POGS group, n = 20). The data were analyzed with an independent t test, the Mann-Whitney U test, the Fisher exact t test, Pearson correlation analysis, and simple linear regression analysis. RESULTS The mean setback of the mandible at point B was similar, but the mandible of the POGS group, particularly the distal segment, moved superiorly during the postoperative period in conjunction with the removal of premature occlusal contacts (P < .001). In the CS group, the mandible had significantly more backward movement 12 months after surgery compared with the POGS group (P < .01). In the POGS group, horizontal and vertical postsurgical changes were linearly correlated with the amount of setback and vertical movement of the mandible. CONCLUSIONS Mandibular setback surgery using IVRO without presurgical orthodontics leads to considerably different postoperative skeletal and dental changes compared with conventional treatment, with more superior movement being observed at point B during the 1-year postoperative period.

Effect of a second injection of botulinum toxin on lower facial contouring, as evaluated using 3-dimensional laser scanning.

BACKGROUND Botulinum toxin type A (BoNT-A) is widely used to improve the lower facial contour. OBJECTIVE To determine the difference in the changes in the lower facial contour achieved with 1 and 2 sessions of BoNT-A injections using 3-dimensional (3D) laser scanning. MATERIALS AND METHODS Twenty volunteers were randomly divided into 2 groups. Group I (n = 10) received a single injection, whereas Group II (n = 10) received 2 sessions of injections, the second being administered 4 months after the first. Each injection comprised of 25 U of BoNT-A and was administered to the masseter muscle bilaterally. Evaluation of the effect of BoNT-A injection was performed using 3D laser scan images obtained before the injection and 6 months thereafter in Group I, and before the first injection and 6 months thereafter in the Group II. RESULTS The mean changes in the volume and thickness in Group I were −1,186 mm3 and –1.52 mm, respectively; the corresponding changes were −4,072 mm3 and –3.84 mm in Group II. The reductions were significantly greater in Group II than in Group I. CONCLUSION The administration of a second BoNT-A injection is effective for better aesthetic results for the lower facial contour.

Five-year investigation of a large orthodontic patient population at a dental hospital in South Korea.

Objective The purpose of this study was to investigate the characteristics of orthodontic patients at Yonsei Dental Hospital from 2008 to 2012. Methods We evaluated Angles classification from molar relationships, classification of skeletal malocclusion from the A point-nasion-B point angle, facial asymmetry, and temporomandibular joint disorders (TMDs) from the records of 7,476 patients who received an orthodontic diagnosis. The orthognathic surgery rate, extraction rate, and extraction sites were determined from the records of 4,861 treated patients. Results The patient number increased until 2010 and gradually decreased thereafter. Most patients were aged 19−39 years, with a gradual increase in patients aged ≥ 40 years. Angles Class I, Class II divisions 1 and 2, and Class III malocclusions were observed in 27.7%, 25.6%, 10.6%, and 36.1% patients, respectively, with a gradual decrease in the frequency of Class I malocclusion. The proportion of patients with skeletal Class I, Class II, and Class III malocclusions was 34.3%, 34.3%, and 31.4%, respectively, while the prevalence of facial asymmetry and TMDs was 11.0% and 24.9%, respectively. The orthognathic surgery rate was 18.5%, with 70% surgical patients exhibiting skeletal Class III malocclusion. The overall extraction rate among nonsurgical patients was 35.4%, and the maxillary and mandibular first premolars were the most commonly extracted teeth. Conclusions The most noticeable changes over time included a decrease in the patient number after 2010, an increase in the average patient age, and a decrease in the frequency of Angles Class I malocclusion. Our results suggest that periodic characterization is necessary to meet the changing demands of orthodontic patients.

Assessment of masticatory function in patients with non-sagittal occlusal discrepancies

Non-sagittal occlusal discrepancies such as posterior cross-bite and anterior openbite are common types of malocclusion, but studies on masticatory function related to those malocclusions have been scarce. The aim of this study was to quantify the masticatory performance in patients with non-sagittal discrepancies compared to those with normal occlusion, using both objective and subjective measures. Maximum bite force and contact area using Dental Prescale(®) system as a static objective assessment, Mixing Ability Index (MAI) as a dynamic objective evaluation and food intake ability (FIA) as a subjective assessment were analysed from 21 people in normal occlusion (Group N) and 64 patients with posterior cross-bite (Group C), anterior openbite (Group O) or both (Group B). The differences of the maximum bite force, the contact area, the MAI and the FIA were compared, and their correlations were figured out. The non-sagittal malocclusion groups showed lower values in the maximum bite force, the contact area, the MAI and the FIA compared to those in the normal group (P < 0·0001). Compared to Group N, Groups C, O and B showed 61·5%, 42·1% and 40·1% of the maximum bite force, and 84%, 84% and 76% of hard food FIA, respectively. However, there were no significant differences among Groups C, O and B. The MAI showed higher correlation with the FIA (r = 0·38, P < 0·01), than with the maximum bite force and the contact area (both r = 0·24, P < 0·5). These results revealed that masticatory function in patients with non-sagittal discrepancies is significantly reduced both objectively and subjectively.

Orthopedic and orthodontic treatment of Parry-Romberg syndrome.

Parry-Romberg syndrome (PRS) is a degenerative disease characterized by progressive hemifacial atrophy of soft and hard tissues. A 10-year-old girl who had been treated for linear scleroderma at the dermatologic department since the age of 9 years visited the orthodontic department. The frontal facial photograph showed mild facial asymmetry. On the left side, mild atrophy of soft tissue, mild enophthalmos, cheek depression, and dry skin with dark pigmentation were observed. The radiograph showed hypoplasia of both the maxilla and mandible on the left side. Intraorally, she was in the mixed dentition with the dental crowding. This case report describes the treatment of a patient with PRS for 7 years. To minimize the effect of progressive atrophy on facial growth, a functional appliance was used. The facial photographs and radiographic records were periodically taken to analyze the progression of PRS. Although it is impossible to prevent the progress of facial asymmetry, it appears to be possible to limit the atrophic effect on the mandible by stimulating the mandibular growth. After stabilization of PRS, orthodontic treatment by fixed appliance was performed. In addition, autologous fat graft was performed 3 times at 6-month intervals. After the treatment, the patient had a confident smile, and facial asymmetry was improved.

Treatment of ankylosed maxillary central incisors by segmental osteotomy with autogenous bone graft

This case report describes the treatment of a 16-year-old girl with ankylosed maxillary central incisors that were noticeably infraoccluded and labially displaced. We performed a segmental osteotomy with an autogenous bone graft in a single-stage surgery to align and level the ankylosed teeth. The dento-osseous segment was successfully repositioned with satisfactory periodontal results.