Jeong Joon Han

Three-dimensional analysis of postoperative returning movement of perioperative condylar displacement after bilateral sagittal split ramus osteotomy for mandibular setback with different fixation methods

This study aimed to evaluate postoperative returning movement of perioperative condylar displacement after bilateral sagittal split ramus osteotomy (BSSRO) depending on a fixation method using three-dimensional (3D) analysis of computed tomography (CT). Twenty-five mandibular prognathic patients (50 condyles) who underwent orthognathic surgery with BSSRO were divided into three groups depending on the fixation method, which consisted of miniplate only (Group A), combined with single bicortical screw (Group B), or with more than one bicortical screw (Group C). CT data taken before, immediately after, and 3 to 6 months after surgery were analyzed. The condyle exhibited mainly lateral bodily displacement and inward and inferior rotation immediately after surgery. The amount of perioperative lateral displacement of the condyle increased according to the increasing number of fixation screws, but the mean displacements were not significantly different among the three groups. During the postoperative follow-up period, the amount of medial returning of the condyle was 102.2% of the intraoperative lateral displacement in Group A. In contrast, Group B and C exhibited partial returning movement by 71.3% and 38.9% of cases, respectively. In conclusion, stronger rigid internal fixation in orthognathic surgery using BSSRO is associated with reduced flexibility of postoperative functional adjustment of displaced condyle to the preoperative condylar position.

Comparative study of BMP-2 alone and combined with VEGF carried by hydrogel for maxillary alveolar bone regeneration

The effect of vascular endothelial growth factor (VEGF) combined with bone morphogenetic protein-2 (BMP-2) for bone regeneration is still controversial as to whether or not VEGF has a synergistic or additive effect. This study attempted to evaluate the synergistic effect of VEGF and BMP-2 compared to BMP-2 alone for maxillary alveolar bone regeneration using collagen sponge/hydrogel complex sheets in a canine model. After mixing BMP-2 and VEGF with a hyaluronic acid-based hydrogel (HAH), the collagen sponge/hydrogel complex was transplanted into maxillary alveolar bone defects (n=14) after the extraction of canine upper first molars on both sides. Bone regeneration was evaluated in three groups (control group without growth factors, experimental groups I and II with BMP-2 alone and BMP-2 and VEGF, respectively) using micro-computed tomography and histological staining. The total amount of new bone formations and bone mineral density were significantly higher in the group with BMP-2 only and the group with BMP-2 combined with VEGF than it in the control group. The area with positive staining of von Willebrand factor bone defect was significantly greater in the group with BMP-2 only and with dual growth factors than the control. BMP-2 released from the HAH promoted new bone formation. However, the combination of BMP-2 and VEGF did not show a synergistic or additive effect on bone regeneration at canine maxillary alveolar bone defects.

Evaluation of early postoperative healing of pterygomaxillary region after LeFort I osteotomy with total maxillary setback movement

OBJECTIVE The aims of this study were (1) to evaluate postoperative stability and (2) to examine bone healing in the pterygomaxillary region after total maxillary setback surgery to correct dentofacial deformities. STUDY DESIGN A total of 27 patients with maxillary protrusion who underwent a 1-piece LeFort I osteotomy and bilateral sagittal split ramus osteotomy were evaluated. The amounts of postoperative relapse were analyzed and compared using cephalometric analysis, and the bone healing in the pterygomaxillary region was evaluated by computed tomography. RESULTS At >6 months after surgery, there was no statistically significant horizontal or vertical relapse. The tendency to relapse did not significantly increase with an extensive amount of maxillary setback. Significant osseous regeneration at the pterygomaxillary region occurred in the early phase of recovery (P < .001). CONCLUSIONS This study suggests that total maxillary setback provides a successful outcome with good stability for the correction of maxillary protrusion.

Evaluation of Mandibular Anatomy Associated With Bad Splits in Sagittal Split Ramus Osteotomy of Mandible.

Purpose:This study aimed to identify risk factors associated with bad splits during sagittal split ramus osteotomy by using three-dimensional computed tomography. Methods:This study included 8 bad splits and 47 normal patients without bad splits. Mandibular anatomic parameters related to osteotomy line were measured. These included anteroposterior width of the ramus at level of lingula, distance between external oblique ridge and lingula, distance between sigmoid notch and inferior border of mandible, mandibular angle, distance between inferior outer surface of mandibular canal and inferior border of mandible under distal root of second molar (MCEM), buccolingual thickness of the ramus at level of lingula, and buccolingual thickness of the area just distal to first molar (BTM1) and second molar (BTM2). Results:The incidence of bad splits in 625 sagittal split osteotomies was 1.28%. Compared with normal group, bad split group exhibited significantly thinner BTM2 and shorter sigmoid notch and inferior border of mandible (P <0.05). However, for BTM1 and buccolingual thickness of the ramus at level of lingula, there was no statistical difference between the 2 groups. Mandibular angle, anteroposterior width of the ramus at level of lingula, external oblique ridge and lingula, and MCEM were not significantly different between the groups. Conclusion:This study suggests that patients with shorter ramus and low thickness of the buccolingual alveolar region distal to the second molar had a higher risk of bad splits. These anatomic data may help surgeons to choose the safest surgical techniques and best osteotomy sites.

Anatomical Studies of the Orbital Cavity Using Three-Dimensional Computed Tomography.

Objective:This study was designed to analyze the morphometric characteristics of the orbital cavity using three-dimensional computed tomography in Asians. Methods:Two hundred seventy-six orbits in 142 Asians (74 men and 68 women) were examined and compared according to age, sex, and laterality (right and left). Results:Mean orbital morphometric values were as follows. Orbital cavity depth was 49.60 mm from optic foramen to orbitale (inferior) and 41.32 mm from optic foramen to lacrimal crest (medial). Anterior and posterior orbital medial wall heights were 17.73 and 12.76 mm, respectively. Medial, middle, and lateral orbital floor lengths were 39.08, 29.56, and 20.08 mm, respectively. Anterior and posterior orbital floor width was 21.87 and 12.00 mm, respectively. For the orbital inferior-medial angle, anterior, middle, and posterior value was 132.11°, 126.24°, and 136.88°, respectively. Inferior orbital cavity depth, anterior orbital medial wall height, and orbital floor length tended to increase with aging, whereas orbital floor width tended to decrease with aging. No significant differences were found in terms of laterality, and values were greater in men than in women. Conclusions:This quantitative analysis of orbital measurements will allow surgeons to plan operations more accurately and will help predict outcomes.

Evaluation of intra-articular distance narrowing during temporomandibular joint movement in patients with facial asymmetry using 3-dimensional computed tomography image and tracking camera system

INTRODUCTION Functional overloading can lead to disc displacement in the temporomandibular joint (TMJ), and a high incidence of disc displacement has been reported in patients with facial asymmetry. The aim of this study was to assess the dynamic condylar movement in patients (n = 26) with facial asymmetry using a simulation system with 3-dimensional computed tomographic images and tracking camera system. MATERIAL AND METHODS The intra-articular distance (IAD) between the condyle and glenoid fossa was recorded during TMJ movement as a parameter for functional overloading and compared between Group I with severe asymmetry and Group II with mild asymmetry. RESULTS The average IAD was shorter in Group I than Group II, especially at the lowest point (P < 0.05). The ratio of IAD narrowing in Group I was significantly larger than in Group II (P < 0.05). The mean IAD were slightly smaller on the deviated side (3.41 mm) than on the nondeviated side (3.55 mm) in Group I, even though there was no statistical significance. The maximum displacement in Group I was longer than in Group II and had no significant difference between deviated side and nondeviated side. CONCLUSION We suggested that the reduced IAD resulting from TMJ overloading can lead to internal derangement in severe facial asymmetry.

Repositioning of the Maxillomandibular Complex Using Maxillary Template Adjusted Only by Maxillary Surface Configuration Without an Intermediate Splint in Orthognathic Surgery.

AbstractAccurate repositioning of the maxillary and mandibular segment is essential to improve esthetics and function in orthognathic surgery. With the improvement of three-dimensional imaging technology and computer-aided design and manufacturing techniques, various computer-aided design and manufacturing templates have been developed as alternatives to the traditional error-prone and time-consuming intermediate splint. However, the majority of previously developed templates still use an intermediate splint or the structures connected to occlusal surface and transferred the preoperative virtual plan to the real operation field indirectly.Here, the authors introduce a technical note regarding maxillary surgical templates adjusted only by the maxillary surface configuration. These templates consist of osteotomy and repositioning guide templates that provide information about the osteotomy line, bony interference, and planned position and eliminate the need for an intermediate splint. Using these templates, the maxillomandibular complex can be successfully repositioned without using an intermediate splint. Further studies are needed to determine the accuracy and stability of maxillary templates.

Clinical and Cephalometric Analysis of Facial Soft Tissue

Objective: This study aimed to provide average of standard values in planning orthognathic surgery in Asians. Materials and Methods: Thirty-three Asians with well-balanced facial profile, combined with class I occlusion and stabilized condylar head were evaluated using lateral cephalograms. Results: Facial length (Nasion′–Menton′) was 138.8 and 127.0 mm in male and female, respectively. Upper and lower lip length were 24.5 and 49.8 mm for male, and 22.2 and 45.1 mm for female, and maxillary incisor exposure was 2.0 and 4.0 mm in male and female, respectively. Nasolabial angle was 77.7° and 84.1° in male and female, respectively. Alar base, A point′, and maxillary incisor were placed posteriorly to true vertical line by 10.6, 1.0, and 8.0 mm for male and 9.0, 0.8, and 6.9 mm for female. The horizontal distance between upper lip anterior and lower lip anterior was 2.1 mm for male and 2.6 mm for female, and the horizontal distance between A point′ and B point′ was 5.3 mm for male and 3.9 mm for female. Orbital rim′ to A-point′ was 12.4 and 11.3 mm in male and female, respectively. Pogonion′ located posteriorly to glabella′ by 2.7 mm for male and anteriorly to glabella′ by 3.2 mm for female, and facial angle was 156.7° and 147.0° in male and female, respectively. Conclusions: This quantitative analysis of facial profile in Asian will be helpful in evaluation of facial soft tissue and establishment of treatment plans for orthognathic surgery.

Maxillary Expansion and Mandibular Setback Surgery With and Without Mandibular Anterior Segment Osteotomy to Correct Mandibular Prognathism With Obstructive Sleep Apnea

Abstract Mandibular prognathism is usually treated with mandibular setback surgery. However, this approach reduces the pharyngeal airway space, and can aggravate obstructive phenomena in patients with obstructive sleep apnea (OSA). While maxillary expansion is known to lead to an increase in the pharyngeal airway volume (PAS), its effect on the PAS in mandibular setback surgery has not yet been reported. The authors report a surgical approach with maxillary expansion in 2 patients with mandibular prognathism that was accompanied by OSA: maxillary midsagittal expansion with minimum maxillary advancement and minor mandibular setback without mandibular anterior segmental osteotomy (ASO) or major mandibular setback with mandibular ASO. Preoperative and postoperative computed tomography and polysomnography indicated that OSA was improved and pharyngeal airway space was increased or sustained, and the prognathic profile could be corrected to an acceptable facial esthetic profile. In summary, maxillary transversal expansion and mandibular setback with or without mandibular ASO can be successfully applied to treat mandibular prognathism with OSA.

Sunken Eye Induced by Superior Orbital Wall Defect After Craniofacial Surgery.

AbstractEnophthalmos after a ventriculo-peritoneal (V-P) shunt placement is very rare. Previous defects of the orbital wall with intracranial hypotension can cause enophthalmos after V-P shunting. The authors present 2 patients of enophthalmos with orbital wall defects resulting from anterior clinoidectomy that was performed during previous aneurysmal surgery. Both patients received a V-P shunt for hydrocephalus after subarachnoid hemorrhage. Although the hydrocephalus was improved by V-P shunts in both patients, sunken eyes were observed. The patients received reconstructive surgery of the superior orbital wall using titanium mesh and recovered after surgery without any neurological deficits. Here, the authors present 2 patients of enophthalmos with orbital wall defects treated by orbital wall reconstruction.