• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.163-167
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• 1990

The author has evaluated the panoramic image of the mandibular condyle according to its horizontal condylar angle (0˚, 10˚, 20°, 30°, 40°) and mandibular position (standard, 25㎜ forward and reverse position). The results were as follows: 1. The larger the horizontal condylar angle was, the larger the horizontal magnification was in all positions. 2. In case of small horizontal condylar angle, profile view could be obtained in 25㎜ forward and reverse position. 3. In case of large horizontal condylar angle, profile view could not be obtained in any positions.

• The Journal of Advanced Prosthodontics
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• v.16 no.4
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• pp.221-230
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• 2024

PURPOSE. This in vitro study was conducted to investigate the accuracy of intraoral scanner (IOS) for recording maximal intercuspal position (MIP) and border positions of the mandible. MATERIALS AND METHODS. Maxillary and mandibular master casts were articulated in MIP, protrusive, and lateral interocclusal position sequentially on a semi-adjustable articulator. For each articulation relation, sites of occlusal contacts (SOCs) and sites of clearance (SCs) were identified on the master casts with articulating paper (reference sites). IOS was used to take full arch scans and nine virtual interocclusal records (VIRs) for virtual articulation of models. Virtual SOCs and SCs were detected with 3D processing software and compared to those identified with the articulating paper. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each articulation relation. RESULTS. For MIP, IOS showed adequate sensitivity and NPV of 100%, and specificity and a PPV of 99%. For protrusive position, the IOS showed a sensitivity and a NPV of 100%, a high PPV of 86%, and a specificity of 83%. For lateral positions, the specificity and the PPV were high (93% and 79%, respectively), but the sensitivity and the NPV were below the clinically acceptable limits (28% and 56%, respectively). CONCLUSION. IOS displayed clinically acceptable accuracy for recording MIP and protrusive border mandibular position. However, IOS had less accuracy for lateral border mandibular position.

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.361-370
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• 2002

The aim of this study was to analyze various data of 120 non-submerged ITI implants placed in 64 korean adults. The data were retrieved from patients' charts and registered in the computer and coded for a statistical analysis. The results revealed that the most common type of edentulism was a distal extension case, and the largest number of implants were placed in the mandibular first molar position. Implants were placed more frequently in mandibular, posterior position than maxillary, anterior position, respectively. With respect to the implant diameter and length, an implant with 4.1mm in diameter and more than 10mm in length was the most common. Since a molar position was the most prevalent position for implant placement in korean patients, clinicians should be careful about implant diameter which can resist a strong occlusal force expected in the molar position. In addition, the distance to the mandibular canal and the floor of maxillary sinus should be considered to avoid possible damages, such as nerve injury and sinus perforation in selecting a proper implant length.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.1
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• pp.21-30
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• 2001

The purpose of this study was to evaluate the skeletal relapse pattern of the mandibular prognathic patients after mandibular set back surgery by sagittal split ramus osteotomy. The horizontal and vertical position of the cephalometric points were measured before, after surgery and after one-year follow up period. The next, the positional change of the proximal and distal mandibular segment were evaluated respectively. The obtained results were as follows; 1. The horizontal and vertical position of Cd was not changed before and after surgery, and it was maintained its original position during the observation periods. 2. As the mandibular prognathism of the patients was severe before surgery, the more skeletal relapse tendency was observed during follow-up period(p<0.05). 3. As the horizontal positional change of the mandible which was obtained by mandibular set-back surgery was large, the more horizontal relapse tendency was observed during follow-up period(p<0.05). 4. The corpus axis angle decreased by sagittal split ramus osteotomy(p<0.01), but it was kept its reoriented position during follow-up period. 5. During the follow-up period after mandibular set-back by sagittal split ramus osteotomy, the forward relapse of mandible correlated with not only the forward rotation of the proximal segment but also the forward movement of the distal segment(p<0.05).

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.61-71
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• 1992

52 Dental students without masticatory problems were selected for this study. They were trained on several mandibular position and mandibular movement exercise, that is, rest position, light bite, tapping, hinge opening, habitual opening, opening limitation, stretch exercise, resistance exercise and clenching. The objectives of this study was to investigate the effects of mandibular movement exercise, especially stretch and resistance, on the experimentally guided limited mouth opening. Muscle activity of the anterior temporalis and the masseter on above mentioned position or exercise were recorded with bioelectric processor EM2(Myotronics, U.S.A.) and the data were processed with SPSS. The obtained results were as follows : 1. Activity of the muscles at rest position were decreased with mandibular movement exercise. 2. Forceful mouth opening on opening limitation increased muscle activity greatly, especially of the masseter. 3. On opening limitation, stretch or resistance exercise was very efficient for decrease of muscle activities. 4. There were no difference of muscle activity between on hinge opening and on habitual opening. Therefore, for muscle relaxation, the two movement exercise can be used interchangeably.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.13 no.1
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• pp.117-126
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• 1983

The mandibular canal must be considered carefully during surgical treatment, especially surgical extraction of the impacted tooth and intraosseous implant because it contains the important inferior alveolar nerve and vessels. The author investigated the curvatUre of the mandibular canal, the positional frequency of mandibular foramen to the occlusal plane and gonial angle and the positional frequency of the mental foramen to the tooth site using orthopantomograms. The materials consisted of 295 orthopantomograms divided into seven groups ranging from the first decade to 6th. decade. The results were as follows: 1. The position of mandibular foramen was most frequently below occlusal plane in Group Ⅰ (78.6%) and Group Ⅱ (71.2%), above occlusal plane in Group Ⅲ (63.0%), Group IV (71.1%), Group V (57.6%), Group (76.7%) and Group VII (70.0%). 2. The curvature of mandibular canal was 142.8° in Group Ⅰ, 142.09° in Group Ⅱ, 139.34° in Group Ⅲ, 141.48° in Group Ⅳ, 138.45° in Group Ⅴ, 140.77° in Group Ⅵ and 143.89° in Group Ⅶ. 3. The gonial angie was 125.82° in Group Ⅰ, 123.18° in Group Ⅱ, 124.06° in Group Ⅲ, 120.45° in Group Ⅳ, 121.12° in Group Ⅴ, 121.63° in Group Ⅵ and 121.24° in Group Ⅶ. 4. The position of the menta] foramen was most frequently below the apex of mandibular first premolar in Group Ⅰ (57.2%), between the apex of mandibular first and second premolar in Group Ⅱ (59.6%) and Group Ⅲ (48.9%), and below the apex of mandibular second premolar in Group Ⅳ (39.2%), Group Ⅴ (48.5%) Group Ⅵ(46.6%) and Group Ⅶ(56.4%)

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.5
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• pp.359-367
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• 2004

Purpose: After the surgical correction with sagittal split ramus osteotomy, the position of the mandibular condyle in the glenoid fossa and the proximal segment of the mandible change because of bony gap between proximal and distal segment, especially in case of mandibular setback asymmetrically. In this study, positional changes in the condyle and proximal segment after BSSRO were estimated in the mandibular asymmetry patient by analyzing the in submentovertex view and P-A cephalogram for identification of ideal condylar position during surgery. Patients and Methods: The 20 patients were selected randomly who visit Dankook Dental Hospital for mandibular asymmetry. Bilateral sagittal split ramus osteotomy with rigid fixation was performed and P-A cephalogram and submentovertex view was taken at the time of preoperative, immediate postoperative, 3 month postoperative period. Results: Intercondylar length and transverse condylar angle was increased due to inward rotation of proximal segment and anteromedial rotation of lateral pole of condyle head. The condylar position had a tendency to return to the preoperative state and after 3 months return up to about half of the immediate post-operative changes, and all the results showed more changes in asymmetry patient and deviated part of the mandible. Conclusion: Based on all these results above, surgeon should make efforts to have a precise preoperative analysis and to have a ideal condylar position during rigid fixation after BSSRO.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.153-161
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• 2008

Purpose : To compare and evaluate the diagnostic ability of cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ). Materials and Methods : CBCT and MRI of 46 TMJs of 23 patients with TMJ disorders were evaluated. They were divided into 3 groups according to the position of the articular disc of the TMJ at closed mouth position and the reduction of the disc during open mouth position on MRI: no disc displacement group (NDD), disc displacement with reduction group (DDR), and disc displacement without reduction group (DDWR). With PACS viewing soft-wares, position of mandibular condyle in the articular fossa, osseous change of mandibular condyle, shape of articular fossa, and mediolateral and anteroposterior dimensions of mandibular condyle were evaluated on CBCT and MRI. Each value was tested statistically. Results : The position of mandibular condyle in the articular fossa were concentric in the NDD, DDR, and DDWR of CBCT and NDD of MRI. However, condyle was positioned posteriorly in DDR and DDWR of MRI. Flattening, sclerosis and osteophyte of the mandibular condyle were much more apparent on DDR of CBCT than MRI. And the erosion of the condyle was much more apparent on DDWR of MRI than CBCT. Box and Sigmoid types of articular fossa were found most frequently in DDR of MRI. Flattened type was found most frequently in DDR of CBCT and deformed type was found most frequently in DDWR of CBCT. No significant difference in mediolateral and anteroposterior dimensions were shown on CBCT and MRI. Conclusion : Since MRI and CBCT has unique diagnostic imaging ability, both modalities should be used together to supplement each other to evaluate TMJ.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.37.1-37.13
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• 2020

Background: The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion. Objectives: The objectives of this study were to determine whether the Sassouni cephalometric analysis could help predict two-dimensional mandibular shape in humans using cephalometric planes and landmarks. Materials and methods: A retrospective computerised analysis of 100 lateral cephalometric radiographs taken at Kingston Hospital Orthodontic Department was carried out. Results: Results showed that the Euclidean straight-line mean difference between the estimated position of gonion and traced position of gonion was 7.89 mm and the Euclidean straight-line mean difference between the estimated position of pogonion and the traced position of pogonion was 11.15 mm. The length of the anterior cranial base as measured by sella-nasion was positively correlated with the length of the mandibular body gonion-menton, r = 0.381 and regression analysis showed the length of the anterior cranial base sella-nasion could be predictive of the length of the mandibular body gonion-menton by the equation 22.65 + 0.5426x, where x = length of the anterior cranial base (SN). There was a significant association with convex shaped palates and oblique shaped mandibles, p = 0.0004. Conclusions: The method described in this study can be used to help estimate the position of cephalometric points gonion and pogonion and thereby sagittal mandibular length. This method is more accurate in skeletal class I cases and therefore has potential applications in craniofacial anthropology and the 'missing mandible' problem in forensic and archaeological reconstruction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.5
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• pp.349-354
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• 2011

Introduction: Mandibular third molar extraction is one of the most common procedures performed in oral and maxillofacial surgery units. Although the overall complication rate is low with most complications being minor, mandibular third molar removal is so common that the population morbidity of complications might be significant. Therefore, efforts to limit intraoperative or postoperative complications might have a significant impact in terms of enhancing the patient outcome. The aims of this study were to identify the position and angulation associated complications after mandibular third molar extractions. Materials and Methods: This study surveyed 568 patients who had a mandibular third molar extracted, showed clinical complications and underwent a radiographic measurement of the available space, depth and spatial relationship. Results: The results obtained were as follows: 1. The complications were a dry socket, nerve injury, root rest, infection, bleeding, hamatoma, and adjacent teeth injury. 2. There were no significant differences between the complication and ramus relationship (available space) of the mandibular third molar. 3. There were no significant differences between the complications and depth of the mandibular third molar. 4. There were no significant differences between the complications and spatial relationship of the mandibular third molar. Conclusion: There were no significant differences in the complication rate, ramus relationship, depth and spatial relationship of the mandibular third molar. This suggests that the position and angulation of the mandibular third molar may not have an impact on the complications. The relationship between the position and angulation of the mandibular third molar, and complications deserves a further study using longitudinal data.