• Archives of Plastic Surgery
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• v.34 no.6
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• pp.777-784
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• 2007

Purpose: For a minor degree of mandibular prognathism, mandibular anterior segmental osteotomy (ASO), usually extracting the bilateral premolars, has been performed frequently to correct malocclusion of the anterior teeth. Preoperative planning using cephalometry and a dental model is very important for such a orthognathic surgery. Depending on the specific preoperative mock surgery with the dental model, ASO, with ipsilateral unitooth extraction, is defined to be feasible and performed for ten patients. The comparisons of its preoperative and postoperative analysis of clinical photographs, dental casts, and lateral cephalograms, for soft tissue profiles, skeletal and dental relationships are described in the following, and its clinical applications are noted. Methods: From March 1, 2004, to March 31, 2006, We performed 10 mandibular ASO by extraction of ipsilateral unitooth to improve their lower facial profiles and the lip relationships. Patient age ranged from 19 to 33 years, with a mean age of 25.6 years. Two were males and eight were females. Results: All patients were satisfied with aesthetic and occlusal changes postoperatively. Significant and persistent decrease in the SNB and interincisal angle were observed in the postoperative cephalometries. The soft tissue profiles also were improved and near Ricketts's esthetic line. Other combined procedures include nine genioplasties, two rhinoplasties, and one blepharoplasty. One patient complained of transient unilateral inferior mental nerve paresthesia. There were no other significant complications or relapses throughout the follow-up period(6-20 months). Conclusion: Mandibular ASO, extracting the ipsilateral unitooth, was performed for ten patients to correct mild mandibular prognathism. The amount of setback of the mandibular anterior portion was 2 to 3 mm, and satisfactory results were obtained combined with genioplasties.

• The korean journal of orthodontics
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• v.46 no.6
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• pp.395-408
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• 2016

We report a case involving a young female patient with severe mandibular retrognathism accompanied by mandibular condylar deformity that was effectively treated with Le Fort I osteotomy and two genioplasty procedures. At 9 years and 9 months of age, she was diagnosed with Angle Class III malocclusion, a skeletal Class II jaw relationship, an anterior crossbite, congenital absence of some teeth, and a left-sided cleft lip and palate. Although the anterior crossbite and narrow maxillary arch were corrected by interceptive orthodontic treatment, severe mandibular hypogrowth resulted in unexpectedly severe mandibular retrognathism after growth completion. Moreover, bilateral condylar deformities were observed, and we suspected progressive condylar resorption (PCR). There was a high risk of further condylar resorption with mandibular advancement surgery; therefore, Le Fort I osteotomy with two genioplasty procedures was performed to achieve counterclockwise rotation of the mandible and avoid ingravescence of the condylar deformities. The total duration of active treatment was 42 months. The maxilla was impacted by 7.0 mm and 5.0 mm in the incisor and molar regions, respectively, while the pogonion was advanced by 18.0 mm. This significantly resolved both skeletal disharmony and malocclusion. Furthermore, the hyoid bone was advanced, the pharyngeal airway space was increased, and the morphology of the mandibular condyle was maintained. At the 30-month follow-up examination, the patient exhibited a satisfactory facial profile. The findings from our case suggest that severe mandibular retrognathism with condylar deformities can be effectively treated without surgical mandibular advancement, thus decreasing the risk of PCR.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.1
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• pp.25-41
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• 1997

The purpose of this study was to observe mandibular condyle shape and position in an asymptomatic population. In order to carry out this study, 142 temporomandibular joints in 71 adults(35 males, 36 females), who were asymptomatic for temporomandibular joint disorders and had no history of prosthodontic or orthodontic treatments, were selected, and radiographed using the Accurd-200 head holder(Denar Co., U.S.A) for transcranial radiograms and the Sectography(Denar Co., U.S.A) for lateral individualized corrected tomograms. Mandibular condyles were classified morphologically and evaluated in positional relationships with articular fossae and articular eminences at centric occlusion and 1 inch mouth opening. The obtained results were as follows; 1. In the classification of mandibular condyle shape, the convex type was more prevalent in transcranial radiograms and tomograms taken at medial, central, and lateral locations. 2. In the mandibular condyle position at centric occlusion, the mandibular condyles were placed posterior to the center of articular fossae in transcranial radiograms and anterior to the center of articular fossae in tomograms taken at medial, central, and lateral locations. 3. In the mandibular condyle position in right and left TMJs at centric occlusion, the mandibular condyles were placed bilateral asymmetric relationships to the articular fossae in transcranial radiograms and tomograms taken at medial, central, and lateral locations. 4. In the mandibular condyle position at 1 inch mouth opening, the mandibular condyles were placed anterior to the articular eminences in transcranial radiograms and tomograms taken at central location and posterior to the articular eminences in tomograms taken at medial and lateral locations.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.6
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• pp.505-511
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• 2011

Purpose: This study evaluated correlation and risk factors between position of the mandibular third molars and mandibular angle fractures using clinical and radiographic findings. Methods: Medical records and panoramic radiographs of 188 patients with mandibular fractures were retrospectively reviewed. The presence and position of the third molars were assessed for each patient and were related to the occurrence of mandibular angle fractures. Results: The incidence of mandibular angle fracture was found to be greater when a lower third molar was present, particularly at the occlusal plane positioned on the $2^{nd}$ molar occlusal surface (by Archer system) and the third molar is impacted in mandibular ramus (by Pell & Gregory system). Of the 192 sites with a lower third molar, 32 (16%) had an angle fracture. Of the 184 site without lower third molars, 16 (8%) had an angle fracture. Conclusion: This study confirmed an increased risk of angle fractures in the presence of a lower third molar as well as variable risk for angle fracture, depending on positioning of the third molar.

• Journal of Oral Medicine and Pain
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• v.19 no.2
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• pp.193-203
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• 1994

The author performed this study for investigation of the magnitude of mandibular positional change caused by joint sound during mandibular opening and closing movement. There have been many studies stated mandibular border movement or other functional movement, and there also have been many studies reported clicking sound related to mandibular movement speed, trajectory and clinicl course of temporomandibular disorders(TMDs), but there have not been so many studies stated spatial mandibular position accompanied by joint sound. For this study 46 TM joint from the patients with TMDs were used and they were compared by character and occuring phase of the joint sound. Synchronized data which were amplitude and frequency of joint sound and amount of mandibular positional change were collected through sonopak and BioEGN rotate of Biopak system, respectively. Mandibular position was analyzed for translational and rotational movement change between before and after joint sound. The obtained data were processed with SAS program and summary of this paper were as follows : 1. Mean value of the amount of translational movement in whole joints were 6.0mm in vertical direction, 3.3mm in anteroposterior direction and 0.8mm in lateral direction between before and after joint sound. 2. Mean value of the amount of translational movement in clicking joinnts showed slightly increased tendency than in popping joints. 3. The amount of mandibular change in translational movement during closing phase were more than during opening phase. 4. The amount of mandibular rotational change in whole joints were $1.1^{\circ}$, 1.0mm in frontal plane and $0.9^{\circ}$, and 0.8mm in horizontal plane. 5. The amount of rotational movement were more in clicking joints than in popping joints and were more during closing phase than during opening phase, but statistically significance were showed only in frontal plane.

• Journal of The Korean Dental Society of Anesthesiology
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• v.9 no.1
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• pp.24-29
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• 2009

When performing the inferior alveolar nerve block anesthesia, surgeon often faced a difficulty of the surgical operation due to the incomplete anesthesia. One of the reason is the variety of mandibular canal anatomy. Up to now, there are some reports of index cases about bifid mandibular canal among mandibular canal anatomic variation, and some classification is applied according to anatomical location and configuration. When surgical operation is performed involving mandible such as dantal implant treatment, extraction of an impacted third molar, sagittal split ramus osteotomy, etc, the position of mandibular canal should be considered. Bifid mandibular canal clinically causes troublesome cases of anesthesia when inferior alvelor nerve block, especially is performed extraction of an impacted third molar. Therefore, It is important for clinicians to recognize the presence of bifid canals on radiographys. Nowadays, the position of mandibular canal can be measured precisely by using Dental CT. It is not found by panorama image but is found by Dental CT sometimes. Among the patients, which take panorama and Dental CT simultaneously, for tooth extraction of lower impacted third molar in our department, we report the case that did not identifying in panorama but identifying it in Dental CT.

• Imaging Science in Dentistry
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• v.36 no.4
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• pp.183-188
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• 2006

Purpose: The purpose of this research was to study bone changes after bilateral sagittal split osteotomy through fractal analysis and measurement of mandibular cortical thickness. Materials and Methods: This study included twenty-two prognathic patients who underwent bilateral sagittal split osteotomy. Panoramic radiographs of these patients were taken immediately before operation and at 1 month, 6 months, and 12 months postoperatively. The fractal dimension was measured by the box-counting method in the region of interest centered on both the basal and interdental bones between the first and second mandibular molars. Measurements of mandibular cortical thickness were taken both in the area between the first and second mandibular molars and at the osteotomy site. Changes of fractal dimension and cortical thickness over four stages were statistically analyzed. Results: The fractal dimension of the mandibular basal bone before surgery and after 1 month, 6 months and 12 months were $1.4099{\pm}0.0657,\;1.382{\pm}0.0595,\;1.2995{\pm}0.0949,\;and\;1.4166{\pm}0.0676$, respectively (Repeated-measures ANOVA, P<0.001). However, no statistically significant differences were noted in interdental fractal dimensions among the four stages. Mandibular cortical thickness between the first and second mandibular molars before operation and after 1 month, 6 months and 12 months was $3.74{\pm}0.48mm,\;3.63{\pm}0.47mm,\;3.41{\pm}0.61mm\;and\;3.55{\pm}0.66mm$ (P<0.01), respectively. Mandibular cortical thickness at the osteotomy site at each of the four stages was $3.22{\pm}0.44mm,\;2.87{\pm}0.59mm,\;2.37{\pm}0.61mm\;and\;2.64{\pm}0.62mm$, respectively (P<0.001). Conclusion: This study suggests that the mandibular tissue continued decreasing for 6 months postoperatively and then increased over the subsequent 6 months.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.108-116
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• 2008

Background : When surgeons plan mandible ortho surgery for patients with skeletal class III facial asymmetry, they must be consider the exact method of surgery for correction of the facial asymmetry. Three-dimensional (3D) CT imaging is efficient in depicting specific structures in the craniofacial area. It reproduces actual measurements by minimizing errors from patient movement and allows for image magnification. Due to the rapid development of digital image technology and the expansion of treatment range, rapid progress has been made in the study of three-dimensional facial skeleton analysis. The purpose of this study was to conduct 3D CT image comparisons of mandible changes after mandibular surgery in facial asymmetry patients. Materials & methods : This study included 7 patients who underwent 3D CT before and after correction of facial asymmetry in the oral and maxillofacial surgery department of Yeungnam University Hospital between August 2002 and November 2005. Patients included 2 males and 5 females, with ages ranging from 16 years to 30 years (average 21.4 years). Frontal CT images were obtained before and after surgery, and changes in mandible angle and length were measured. Results : When we compared the measurements obtained before and after mandibular surgery in facial asymmetry patients, correction of facial asymmetry was identified on the "after" images. The mean difference between the right and left mandibular angles before mandibular surgery was $7^{\circ}$, whereas after mandibular surgery it was $1.5^{\circ}$. The right and left mandibular length ratios subtracted from 1 was 0.114 before mandibular surgery, while it was 0.036 after mandibular surgery. The differences were analyzed using the nonparametric test and the Wilcoxon signed ranks test (p<0.05). Conclusion: The system that has been developed produces an accurate three-dimensional representation of the skull, upon which individualized surgery of the skull and jaws is easily performed. The system also permits accurate measurement and monitoring of postsurgical changes to the face and jaws through reproducible and noninvasive means.

• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.376-381
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• 2019

Background: This study was conducted to determine the relationship between third molar (M3) and mandibular fracture. Methods: Patients with unilateral mandibular angle or condyle fractures between 2008 and 2018 were evaluated retrospectively. Medical records were reviewed regarding the location of fractures, and panoramic radiographs were reviewed to discern the presence and position of ipsilateral mandibular third molars (M3). We measured the bony area of the mandibular angle (area A) and the bony area occupied by the M3 (area B) to calculate the true mandibular angle bony area ratio (area A-B/area A×100). Results: The study consisted of 129 patients, of which 60 (46.5%) had angle fractures and 69 (53.5%) had condyle fractures. The risk of angle fracture was higher in the presence of M3 (odds ratio [OR], 2.2; p< 0.05) and the risk of condyle fracture was lower in the presence of M3 (OR, 0.45; p< 0.05), than in the absence of M3. The risk of angle fracture was higher in the presence of an impacted M3 (OR, 0.3; p< 0.001) and the risk of condyle fracture was lower in the presence of an impacted M3 (OR, 3.32; p< 0.001), than in the presence of a fully erupted M3. True mandibular angle bony area ratio was significantly lower in the angle fractures than in the condyle fractures (p= 0.003). Conclusion: Angle fractures had significantly lower true mandibular angle bony area ratios than condyle fractures. True mandibular angle bony area ratio, a simple and inexpensive method, could be an option to predict the mandibular fracture patterns.

• The korean journal of orthodontics
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• v.50 no.2
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• pp.129-135
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• 2020

Objective: This study aimed to evaluate the immediate effects of mandibular posterior displacement on the pharyngeal airway space (PAS) by using cephalometric evaluations and to investigate how the surrounding structures are schematically involved. Methods: In this retrospective study, 38 subjects with functional Class III malocclusion and two lateral cephalograms were selected. The first lateral cephalogram was taken with the mandible in the habitual occlusal position, and the second in anterior edge-to-edge bite. Paired t-test was used to analyze changes in the PAS, hyoid bone, tongue, and soft palate, followed by mandibular posterior displacement. Pearson's correlation analysis was used to determine the relationship between the amount of mandibular posterior displacement and other variables. Results: A statistically significant decrease was observed in the PAS following mandibular posterior displacement. Along with mandibular posterior displacement, the tongue decreased in length (p < 0.001) and increased in height (p < 0.05), while the soft palate increased in length, decreased in thickness, and was posteriorly displaced (p < 0.001). The hyoid bone was also posteriorly displaced (p < 0.05). There was no correlation between the amount of mandibular posterior displacement and the measured variables. Conclusions: The PAS showed a statistically significant decrease following mandibular posterior displacement, which was a consequence of retraction of the surrounding structures. However, there were individual variances between the amount of mandibular posterior displacement and the measured variables.