Dae-Seok Hwang

Effect of Bimaxillary Surgery on Adaptive Condylar Head Remodeling: Metric Analysis and Image Interpretation Using Cone-Beam Computed Tomography Volume Superimposition

PURPOSE The aim of the present study was to use cone-beam computed tomography volume superimposition to investigate the effect of bimaxillary orthognathic surgery on condylar head remodeling. MATERIALS AND METHODS Using a retrospective study design, 2 investigators evaluated the cone-beam computed tomography data of subjects who had undergone Le Fort I osteotomy and mandibular setback surgery. The predictor variable was time, grouped as preoperative versus postoperative. The outcome variables were the measurement changes of the condylar heads and the distribution of the condylar head remodeling signs. Paired t and χ(2) tests were performed for the purposes of the 2-dimensional metric analysis and the condylar head remodeling distribution. P < .05 was considered significant. RESULTS The sample was composed of 22 adults (11 men and 11 women, age 20.3 ± 3.2 years) diagnosed with skeletal Class III malocclusion. The intra- and interoperator reliabilities of the image interpretation showed substantial agreement, according to Cohens kappa index. The condylar heights on the sagittal and coronal planes decreased after surgery. Bone resorption occurred predominantly in the anterior and superior areas on the sagittal plane, the superior and lateral areas on the coronal plane, and the anterolateral and posterolateral areas on the axial plane (P < .05). Bone formation was apparent only in the anteromedial area on the axial plane (P < .05). CONCLUSIONS Bimaxillary orthognathic surgery caused a decrease in the condylar heights and condylar head remodeling. The cone-beam computed tomography volume superimposition method showed that the condylar head had undergone remodeling after bimaxillary surgery.

Midfacial Soft-Tissue Changes After Advancement of Maxilla With Le Fort I Osteotomy and Mandibular Setback Surgery: Comparison of Conventional and High Le Fort I Osteotomies by Superimposition of Cone-Beam Computed Tomography Volumes

PURPOSE To compare the soft-tissue changes in the midfacial areas of patients who underwent conventional and high Le Fort I osteotomies with maxillary advancement, using voxel-by-voxel registration at the cranial bases, and to evaluate the influence of the level of the osteotomy cut on those soft-tissue changes. MATERIALS AND METHODS The subjects included 42 patients (28 in group 1 and 14 in group 2) who had undergone conventional or high Le Fort I osteotomy with maxillary advancement and mandibular setback sagittal split ramus osteotomy. Using the method involving superimposition of 3-dimensional cone-beam computed tomography volumes, we evaluated the soft-tissue changes preoperatively and postoperatively. The midfacial area was measured with a 10 × 27 grid at 4.5-mm (vertical) and 5-mm (horizontal) intervals. RESULTS The maxillary advancement in group 1 averaged 3.35 ± 1.06 mm at the A-point and 3.23 ± 0.98 mm at the same location in group 2. Both of the Le Fort I osteotomies induced an overall hard-to-soft tissue response in the midfacial area (P < .05). CONCLUSIONS In group 1, the distinctly changed soft tissue was marked near the osteotomy line and upper lip. The distribution of the changed points was within a roughly triangular area between the 2 nasolabial folds and the upper lip. In group 2, the soft-tissue changes were concentrated just below the infraorbital foramen. The distribution of the affected soft tissue after the high Le Fort I osteotomy was within the rectangular malar region between the 2 infraorbital foramens and the upper lip.

A comparative study of the effectiveness of sinus bone grafting with recombinant human bone morphogenetic protein 2–coated tricalcium phosphate and platelet-rich fibrin–mixed tricalcium phosphate in rabbits

OBJECTIVES The objective of this histologic study was to evaluate platelet-rich fibrin (PRF)-mixed tricalcium phosphate (TCP) and recombinant human bone morphogenic protein 2 (rhBMP-2)-coated TCP in their potential to enhance bone regeneration in sinus elevation in rabbits as well as in their inflammatory features. STUDY DESIGN Bilateral round-shaped defects (diameter 8.0 mm) were formed in the maxillary anterior sinus walls of 36 New Zealand white rabbits. The defects were grafted with TCP only (control group), with rhBMP-2-coated TCP (experimental group A) and with PRF-mixed TCP (experimental group B). Each group included 12 rabbits. The animals were killed at 3 days, 1 week, 2 weeks, 4 weeks, 6 weeks, and 8 weeks. The specimens underwent decalcification and were stained for histologic analysis. RESULTS There were no significant differences in inflammatory features among the groups at 3 days or the first week after operation. In a histomorphometric analysis, the new bone formation ratio showed significant differentiation between groups A and B. The TCP-only control group showed a relatively lower bone formation ratio rather than the experimental groups. The PRF-mixed TCP group showed a larger bone formation area, compared with both the control group and group A. CONCLUSIONS In the results of the histologic evaluation (hematoxylin-eosin, Masson trichrome stain), the experimental groups A and B showed rapid bone formation, remodeling, and calcification in the second week. Moreover, there was a significant difference between those experimental groups and the control group in the new bone formation area at the fourth, sixth, and eighth weeks. The PRF-mixed TCP showed more rapid bone healing than the rhBMP-2-coated TCP or the TCP-only control.

Midfacial soft-tissue changes after mandibular setback surgery with or without paranasal augmentation: cone-beam computed tomography (CBCT) volume superimposition.

The aim of this article is to compare the soft-tissue changes in the midfacial areas of patients who had undergone mandibular setback sagittal split ramus osteotomy (SSRO) with that of mandibular setback SSRO with paranasal augmentation. The subjects included 15 patients (group I), SSRO with paranasal augmentation and 20 patients (group II), SSRO alone. To evaluate the difference of the midfacial soft-tissue changes between groups, cone-beam computed tomography superimposition was utilized and the soft-tissue changes were measured both preoperatively and postoperatively by a 10 × 27 grid. In group I, the soft tissues were changed at the areas bounded superiorly by the infraorbital foramen, zygomatic eminence, posteriorly by the masseteric muscle and medially by the lateral aspect of the nose and following the nasolabial fold. In group II, the midfacial soft-tissue measurements were unchanged. This study may help clinicians to predict improvement in the midfacial region from mandibular setback SSRO with or without a paranasal augmentation procedure in class III deformities.

The reliability of cone-beam computed tomography (CBCT) – Generated frontal cephalograms

BACKGROUND The purpose of this study was to evaluate the reliability of measurements from cone-beam computed tomography (CBCT)-generated frontal cephalogram. MATERIALS AND METHODS CBCT and conventional posteroanterior (PA) cephalograms were taken from 30 adult patients. CBCT image was set according to the Frankfurt-Horizontal (FH) plane as the horizontal plane and the midsagittal reference (MSR) plane. The CBCT frontal cephalograms were generated using the orthogonal Raycast method (group CT(raycast)), the orthogonal maximum intensity projection (MIP) method (group CT(MIP)) after the head reorientation according to the reference planes, and the generator tool provided by the employed 3-dimensional (3D) imaging software (group CT(generator)), respectively. The differences between the CBCT-generated frontal cephalograms and conventional PA cephalograms (group PA(ceph)) were compared by paired t-test (p<0.05). RESULTS The significant differences were shown in two measurements for group CT(raycast), in 12 measurements for group CT(MIP), and in eight measurements for group CT(generator). It was confirmed that the CBCT frontal cephalograms, generated by means of the Raycast method (Group CT(raycast)), were more comparable to the conventional PA cephalograms in their measurements than were the others (Groups CT(MIP), CT(generator)). CONCLUSION This study may well suggest that frontal cephalograms derived by 3D CBCT reorientation can be effectively employed in clinical applications.

Effect of maxillary setback movement on upper airway in patients with class III skeletal deformities: cone beam computed tomographic evaluation.

AbstractThe purpose of this study was to investigate, through cone beam computed tomography, volumetric changes to the upper airway space in patients with skeletal class III skeletal deformities who had undergone mandibular setback surgery (group A [n = 24]) or bimaxillary surgery (mandibular setback surgery and maxillary setback Le Fort I osteotomy; group B [n = 23]). All of the patients underwent a cone beam computed tomographic examination for assessment of the upper airway volume and skeletal changes before surgery (T0) and 6 months after surgery (T1). In an evaluation of the anatomic characteristics of the upper airway, the anteroposterior length (APL), the largest transverse width (LTW), and the cross-sectional area (CSA) on the axial planes (the posterior nasal spine-posterior point of vomer (PNS-Vp), 1st cervical vertebra (CV1), 2nd cervical vertebra (CV2), 3rd cervical vertebra (CV3), and 4th cervical vertebra (CV4) planes) were calculated at T0 and T1. No significant differences between the groups A and B (P > 0.05) were found. In group A, the mandibular setback movement affected the oropharyngeal and hypopharyngeal volumes and reduced the APL, the LTW, and the CSA on the CV1, CV2, and CV3 planes (P < 0.05). The APL and the CSA on the CV4 plane also were reduced (P < 0.05). In group B, the maxillary and mandibular setback movement narrowed the upper airway volumes. Specifically, the APL on the CV1, CV2, CV3, and CV4 planes, the LTW on the PNS-Vp, CV1, and CV3 planes, and the CSA on the PNS-Vp, CV1, CV2, CV3, and CV4 planes decreased after the surgery (P < 0.05). Between the 2 groups, there were statistical differences (P < 0.05) in the APL, the LTW, and the CSA on the PNS-Vp plane.

The impact factors on 5-year survival rate in patients operated with oral cancer

Objectives The purpose of this study is to analyze clinical impact factors on the survival rate, and to acquire basic clinical data for the diagnosis of oral cancer, for a determination of the treatment plan with long-term survival in oral cancer patients. Materials and Methods Through a retrospective review of the medical records, the factors for long-term survival rate were analyzed. Thirty-seven patients, among patient database with oral cancer treated in the Department of Oral and Maxillofacial Surgery at Pusan National University Hospital within a period from March 1998 to March 2008, were selected within the study criteria and were followed-up for more than 5 years. The analyzed factors were gender, age, drinking, smoking, primary tumor site, type of cancer, TNM stage, recurrence of affected region, and metastasis of cervical lymph node. The 5-year survival rate on the impact factors was calculated statistically using the Kaplan-Meier method. Results By classification of clinical TNM at the 1st visit, there were 11 (29.7%) cases for stage I, 11 (29.7%) cases for stage II, 3 (8.1%) cases for stage III, and 12 (32.5%) cases for stage IV. The 5-year survival rate of total oral cancer patients after the operation were 75.7%, pathological TNM stage related 5-year survival rate were as follows: stage I 90.0%, stage II 81.8%, stage III 100% and stage IV 45.5%; in which the survival rate difference by each stage was significantly observed. The recurrence of cervical lymph node was the significant impact factor for the survival rate, because only 30.0% the survival rate in recurrent cases existed. During the follow-up, there were 15 (40.5%) patients with confirmed recurrence, and the 5-year survival rate of these patients was decreased as 46.7%. Conclusion The classification of clinical and pathological TNM stage, local recurrence after surgery, and metastasis of cervical lymph node after surgery were analyzed as the 3 most significant factors.

Osteoblastic response to the hydroxyapatite/gelatin nanocomposite and bio-calcium phosphate cement

The main purpose of the developingnew CPCs by modulating their components or ratios are to develop more proper biomaterials which can adapt to the body. In the present study, the properties of newly developed HAp/Gel Nanocomposites were tested using in-vitro experiments (The toxicity test, chromosomal aberration test, cytokinesis-block micronucleus assay, RT-PCR analysis). The data from the WST-1 experiments using HAp/Gel and human osteoblastic cells showed that this material does not induces cellular death. And this material did not induced any significant changes in the structures of chromosomes. The expression pattern of integrins after treatment with CPC or HAp/Gel powder represents that the cells in CPC forms focal adhesion as the cells on adhesive culture dish, but the cells in HAp/Gel do not. By performing several set of experiments, HAp/Gel is not toxic to hFOB-1.19 human osteoblast cell and does not cause any genetic problems. In contrast to CPC, HAp/Gel promotes the final differentiation of osteoblast into osteocyte. These results represent the improved bio-mimetic properties of HAp/Gel.

Differentiation and characteristics of undifferentiated mesenchymal stem cells originating from adult premolar periodontal ligaments

Objective The purpose of this study was to investigate the isolation and characterization of multipotent human periodontal ligament (PDL) stem cells and to assess their ability to differentiate into bone, cartilage, and adipose tissue. Methods PDL stem cells were isolated from 7 extracted human premolar teeth. Human PDL cells were expanded in culture, stained using anti-CD29, -CD34, -CD44, and -STRO-1 antibodies, and sorted by fluorescent activated cell sorting (FACS). Gingival fibroblasts (GFs) served as a positive control. PDL stem cells and GFs were cultured using standard conditions conducive for osteogenic, chondrogenic, or adipogenic differentiation. Results An average of 152.8 ± 27.6 colony-forming units was present at day 7 in cultures of PDL stem cells. At day 4, PDL stem cells exhibited a significant increase in proliferation (p < 0.05), reaching nearly double the proliferation rate of GFs. About 5.6 ± 4.5% of cells in human PDL tissues were strongly STRO-1-positive. In osteogenic cultures, calcium nodules were observed by day 21 in PDL stem cells, which showed more intense calcium staining than GF cultures. In adipogenic cultures, both cell populations showed positive Oil Red O staining by day 21. Additionally, in chondrogenic cultures, PDL stem cells expressed collagen type II by day 21. Conclusions The PDL contains multipotent stem cells that have the potential to differentiate into osteoblasts, chondrocytes, and adipocytes. This adult PDL stem cell population can be utilized as potential sources of PDL in tissue engineering applications.

Sequential treatment for a patient with hemifacial microsomia: 10 year-long term follow up

Hemifacial microsomia (HFM) is the most common craniofacial anomaly after cleft lip and cleft palate; this deformity primarily involves the facial skeleton and ear, with either underdevelopment or absence of both components. In patients with HFM, the management of the asymmetries requires a series of treatment phases that focus on their interception and correction, such as distraction osteogenesis or functional appliance treatment during growth and presurgical orthodontic treatment followed by mandibular and maxillary surgery. Satisfactory results were obtained in a 9-year-old girl with HFM who was treated with distraction osteogenesis. At the age of 19, genioplasty and mandible body augmentation with a porous polyethylene implant (PPE, Medpor®, Porex) was sequentially performed for the functional and esthetic reconstruction of the face. We report a case of HFM with a review of the literature.