• The Journal of Advanced Prosthodontics
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• 제3권1호
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• pp.51-55
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• 2011

BACKGROUND. Mandibular displacement is a common complication of condylar fracture. In the mandibular displacement due to condylar fracture, it is difficult to restore both esthetics and function without using orthognathic surgery. CASE DESCRIPTION. This clinical report described a full mouth rehabilitation in the patient with bilateral condylar fractures and displaced mandible using bilateral sagittal split ramus osteotomy (BSSRO) and simultaneous dental implant surgery. Mandibular position was determined by model surgery through the diagnostic wax up and restoration of fractured teeth. The precise amount of the mandibular shift can be obtained from the ideal intercuspation of remaining teeth. CLINICAL IMPLICATION. Mandibular displacement by both condylar fractures can be successfully treated by orthognathic surgery. Determination of occlusal plane and visualization from diagnostic wax up are mandatory for mandibular repositioning of model surgery. Stable occlusion and regular recall check up are needed for long-term outcome.

• Imaging Science in Dentistry
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• 제37권1호
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• pp.9-14
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• 2007

Purpose : To determine the more valuable information to detect the mandibular canal and the mental foramen in panoramic radiographs of a selected Korean population for the implant. Materials and Methods : This study analysed 288 panoramic radiographic images of patients taken at the Dental hospital of Chosun University retrospectively. Indirect digital panoramic X-ray machine (ProlineXC, PLANMECA, Finland) with processing by using Directview $CR950^@$ (Kodak, U.S.A.) and Direct digital panoramic X-ray machine (Promax, PLANMECA, Finland) were used for all exposures. All images were converted into Dicom format. Results : The common position of the mental foramen was in line with the longitudinal axis of the second premolar (68.1%). The mental foramen was symmetrical in 81.8% of cases. The mandibular canal was not identified at anterior portion and discontinued with the mental foramen in 27.8% of all cases, in 42.4% identified with lower border line continued with the mental foramen, in 14.6% with both upper and lower border lines, and in 15.3% unilaterally identified with lower border line. Conclusion : Clinicians can estimate the upper border line of the mandibular canal from the confirmation of the mental foramen and the lower border line of the mandibular canal symmetrically on the panoramic radiography taken in adjusted midsaggital plane of patient's head.

• 치과방사선
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• 제17권1호
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• pp.209-222
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• 1987

The author invested the gonial angle, the angle of mandibular and mental canal to the lower border of the mandible, and a relationship of the position of the mandibular canal to the root apex of the posterior teeth and the cortical plate of the lower of the mandible. The materials consisted of 458 pantomograms in male and female aged 11-40 and divided into 5 groups at 5 year intervals and subdivided into 3 groups by gonial angle. The results were as follows; 1. The gonial angle decreased with age, but slight increase occurred over 26-30 years. 2. The average angle of the mandibular canal to the lower border of the mandible was 151.6° and did not correlate with age. 3. The average angle of the mental canal to the lower border of the mandible was 36.9° and didn't correlate with age. 4. The angles of mandibular and mental canal to the lower border of the mandible correlated with gonial angle. 5. The distance from the root apex of the posterior teeth to the upper wall of the mandibular canal was most short at the region of the distal root of the mandibular second molar and increased with age at the region of the mandibular second molar. 6. The distance from the lower wall of the mandibular canal to the cortical plate of the lower border of the mandible was most short at the region of the mesial root of the mandibular first molar and didn't correlate with age.

• 대한두개안면성형외과학회지
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• 제20권6호
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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.

• 대한치과교정학회지
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• 제50권2호
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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.

• Imaging Science in Dentistry
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• 제42권3호
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• pp.121-127
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• 2012

Purpose: This study evaluated the association between cone beam computed tomography (CBCT) and panoramic radiographs in the assessment of a superimposed relationship between the mandibular canal and impacted third molars. Materials and Methods: The study samples consisted of 175 impacted third molars from 131 patients who showed a superimposed relationship between the mandibular canal and third molars on panoramic radiographs and were referred for the examination of the mandibular canal with CBCT. Panoramic images were evaluated for the darkening of the root and the interruption of the mandibular canal wall. CBCT images were used to assess the buccolingual position of the mandibular canal relative to the third molar, the proximity of the roots to the canal, and lingual cortical bone loss. The association of the panoramic and CBCT findings was examined using a Chi-square test and Fisher's exact test. Results: Panoramic radiographic signs were statistically associated with CBCT findings (P<0.01). In cases of darkening roots, lingual cortical bone loss or buccally positioned canals were more frequent. In cases in which the mandibular canal wall was interrupted on panoramic radiographs, contact or lingually positioned canals were more frequent. Conclusion: The results of this study suggest that contact between the mandibular third molar and canal and a lingually positioned canal could be more frequently observed in cases of the interruption of the white line of the mandibular canal and that there could be more lingual cortical loss in cases of darkening roots.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.30.1-30.7
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• 2017

Background: The positions of the mandibular lingula and foramen have been set as indexes for inferior alveolar nerve (IAN) block and ramus osteotomies in orthognathic surgery. This study aimed to evaluate the anatomical structures of mandibular ramus, especially the mandibular lingula and foramen, by analyzing the cone-beam computed tomography (CBCT) data of young adults. Methods: We evaluated 121 sides of hemi-mandibular CBCT model of 106 patients (51 male and 55 female patients; 18 to 36 years old). All the measurements were performed using the 2- and 3-dimensional rulers of $OnDemand3D^{(R)}$ software. Results: Statistical analysis of the data revealed that there was no significant difference in the mandibular angle between the genders. The mandibular lingula was found to be located at the center of ramus in males, but a little posterior in relation to the center in females. The mandibular lingula was rarely located below the occlusal plane; however, the position of the mandibular foramen was more variable (84.3% below, 12.4% above, and 3.3% at the level of the occlusal plane). Conclusions: The results of this study provide a valuable guideline for IAN block anesthesia and orthognathic surgery. CBCT can be considered effective and accurate in evaluating the fine structures of the mandible.

• 대한치과보철학회지
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• 제18권1호
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• pp.73-86
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• 1980

Recently, the controversy continues as to whether maximum intercuspation of teeth should occur at the terminal hinge position(the condylar theory) or at the myo-co(the neuromuscular theory). There is also much controversy regarding the antero-posterior position of myo-co. The object of this study was to measure and compare with the positional relations of centric relation, centric occlusion and myo-co, and free-way space using Mandibular Kinesiograph and Myo-monitor in the 40 subjects without stomatognathic problems. Mandibular Kinesiograph(M.K.G.) was originally conceived as a research instrument to track mandibular movement and position. As its use in research progressed, its great diagnostic value became apparent in case by case. And Myo-monitor was developed as a means of applying the neuromuscular approach to occlusion. Thus the Myo-monitor technique is an intra-systemic approach to occlusal positioning using patient's own musculature, and Myo-monitor is used to relax the musculature by a light myopulse induced electronically. From this experiment, the following results were obtained. 1. The adaptive free-way space before muscle relaxation was an average of $1.6{\pm}60mm$, and the true free-way space after muscle relaxation using Myo-monitor was an average of $2.4{\pm}0.74mm$. 2. It took an average of $25{\pm}3.11$ minutes to relax the mandibular musculature by Myo-monitor and administration of 5mg. Diazepam and an average of $38{\pm}4.73$ minutes by Myo-monitor without administration of Diazepam. 3. Myo-co existed anterior to centric occlusion, with an average of $0.53{\pm}0.31$ mm, and centric relation existed posterior to centric occlusion, with an average of $0.57{\pm}0.58mm$ before muscle relaxation and with an average of $0.57{\pm}0.43mm$ after muscle relaxation. 4. Centric relation coincided with centric occlusion in 5 of 40 subjects(12.5%), and posterior to centric occlusion in the rest of cases (87.5%). 5. Myo-co existed anterior to centric occlusion in 38 of 40 subjects(95%), except 1 subject that coincided with centric occlusion and 1 subject that existed posterior to centric occlusion. 6. Myo-co and centric relation existed inferior to centric occlusion and the lateral displacement was various with individual difference. 7. The total displacement from centric occlusion to centric relation was an average of $0.74{\pm}0.64mm$ before muscle relaxation, and an average of $0.68{\pm}0.53mm$ after muscle relaxation, and the total displacement from centric occlusion to myo-co was an average of $1.07{\pm}0.58mm$.

• 대한치과교정학회지
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• 제19권1호
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• pp.153-167
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• 1989

This study was undertaken to analyze the growth of mandible in surgically repaired unilateral cleft lip and palate. The subjects consisted of 63 unilateral cleft lip and palate individuals, 60 class III malocclusions and 60 normal occlusions ranging from 6 to 15 years old. Each group was divided into two age groups. (6-10 Y and 11-15 Y) The results obtained from UCLP compared with other groups were as follows: 1. The anteroposterior position of the chin was similar to that of the normal occlusions. 2. The shape of the mandible was similar to that of the class III malocclusions. 3. In mandibular size, ramus height was the smallest among three groups, but body length and overall mandibular length were similar to those of the normal occlusions. 4. The lower border of the mandible was the steepest among three groups and strong vertical or clockwise growth tendency was indicated. 5. The position of condyle in relation to the cranial base showed little difference in three groups. 6. In older age group , vertical growth tendency of the mandible decreased more or less.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제35권4호
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• pp.211-220
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• 2013

Purpose: The purpose of this study was to compare the changes in the pharyngeal airway space, tongue and hyoid bone positions according to the orthognathic surgical methods of mandibular prognathism. Methods: The subjects included 30 patients (16 males, 14 females) with the skeletal class III malocclusion. Group 1 (10 patients) underwent bilateral sagittal split ramus osteotomy (BSSRO) only; group 2 (10 patients) underwent BSSRO with genioplasty; and group 3 (10 patients) underwent BSSRO, Le Fort I osteotomy. We measured the lines between the selected upper air way, hyoid bone and tongue landmarks on the lateral cephalometric x-ray films of skeletal class III. The measurements were made preoperation, within 1 week after the operation, 3~6 months after the operation and 1 year after the operation. We compared and analyzed the measurements with matched paired t-test and independent samples t-test. Results: There were no postoperative changes in the nasopharyngeal airway space in group 3. The measurements of group 3 also increased during the follow-up period as compared to the preoperative measurements. In group 1, 2 and 3, the immediate postoperative oropharyngeal and hypopharyngeal airway spaces were decreased. In the following period, the hypopharyngeal airway space returned to the preoperative positions, but the oropharyngeal airway space was not significantly changed. The upper and lower tongue was posteriorly repositioned immediately after the surgery. During the follow-up period, the lower tongue position returned to the preoperative position, and the upper tongue position was not significantly changed. Immediately after the surgery, the B point was moved to the posterior position, and a slight anterior advancement was found in the follow-up period. Conclusion: Patients who received the mandibular setback surgery showed a decrease in the posterior airway space, and those who underwent maxillary advancement showed a significant increase of the nasopharyngeal airway space, which remained stable during the evaluation period. The change of the airway space, position of the hyoid bone and tongue did not differ according to the presence or absence of genioplasty.