• The korean journal of orthodontics
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• v.24 no.2
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• pp.275-294
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• 1994

The occlusal interference during adolescent period makes some effects on growth and development and morphological changes. And so, if we could predict the the timing and results of orthodontic treatment who have occlusal interference during adolescent period, it may be helpful for diagnosis and treatment planning of orthodontic treatment. For about those, the purpose of this study was to evaluate the effects of the posterolateral displacement by the metal casting crown with inclined pathway on the mandibular condyle and morphologic changes of mandible in the rat. The experimental animals were thirty six Sprague-Dawley male rats of 8 weeks old. Eight of them was used as control group, and experimental group 1 ( continuous appliance wearing group ) was composed of sixteen and experimental group 2 ( appliance removal group after worn the appliances during 3 months ) was composed of remaining twelve. The animals of experimental grouop 1 were sacrificed after 1, 2, 3, 6 months from beginning of the experiment and experimental group 2 were sacrificed 1, 2, 3 months after removal of the appliance from worn the appliance during 3 months. Both of mandible and temporomandibular joint were observed histologically and radiologically. The results were as follows : 1. In experimental group 1, the mandibular length and lower posterior height were decreased with experimental period, while the lower anterior height was increased, and the curvature of lower incisors and lingual inclination of anterior alveolar bone were profound as compared with control group. 2. In experimental group 1, both of the thickness of the condylar cartilage were thinned in the posterosuperior region, and this phenomenon was more prominent on right than left in 3-Mo experimental period and both sides were marked thinned in 6-Mo experimental period. 3. In experimental group 2, the lower anterior height was low and lower posterior height was high as compared with experimental group 1, and the curvature of lower incisors and lingual inclination of anterior alveolar bone were recovered to control group. 4. In experimental group 2, both of the thickness of the condylar cartilage were thickened in the posterosuperior region, and this phenomenon was more prominent with experimental period. 5. In experimental group 2, the mandibular length was short, lower anterior height was hight, the curvature of lower incisors were profound, and in histologically, both of the thickness of the condylar cartilage were thickened in the posterosuperior region as compared with control group. As shown above, the occlusal interfemce affected the condylar cartilage, curvature of lower incisor, inclination of anterior alveolar bone, mandibular length, and anterior and posterior height. When the interference was removed, significant recover was found in condylar cartilage, mandibular length, and posterior height. Although no significance was found, other items of measurement showed trends for recovery.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.299-313
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• 1990

The author analysed tomographic and cephalometric radiographs of 82 temporomandibular joints from 41 symptomatic patients and 40 temporomandibular joints from 20 asymptomatic young adults. The results were as follows; 1. The mean condylar angulation in control group and patient group was 21.72±6.48° 20.13±9.14° respectively and there was no significant difference between two groups. 2. The mean depth of cut was 6.63±0.38㎝ in control group and 6.57±0.46㎝ in patient group. 3. Mean height and width of condylar head were 6.66±1.83㎜, 12.42±0.49㎜ in control group and 6.22±1.36㎜, 11.93±l.92㎜ in patient group. 4. The mean height of articular fossa was 10.20±2.04㎜ in control group and 9.89±1.98㎜ in patient group. The mean width of articular fossa was 21.08±2.08㎜ in control group and 21.24±3.03㎜ in patient group. 5. In centric occlusion the superior joint space was largest (4.15±0.93㎜), followed by the posterior joint space (2.99±0.97㎜) and the anterior joint space (2.70±0.73㎜) in control group. The superior joint space (3.47±1.31㎜) and posterior joint space (3.47±7.07㎜) were same in patient group. There was significant difference in left superior joint spaces between two groups (p<0.05). 6. The condylar position in articular fossa was displaced anteroinferiorly (0.99±3.65㎜ anteriorly, 1.75±1.01㎜ inferiorly) in control group and posteroinferiorly (3.20±4.69㎜ posteriorly, 1.25±1.87㎜ inferiorly) in patient group with 1 inch opening. In maximum opening, it was displaced anteroinferiorly (6.09±3.55㎜ anteriorly, 1.38±2.47㎜ inferiorly) in control group and anteroinferiorly (1.70±5.96㎜ anteriorly, 1.37±1.85㎜ inferiorly) in patient group. There was significant difference in anteroposterior position of both condyles with 1 inch opening and maximum opening between two groups (p<0.01). 7. The mean inclination of upper central incisor and the posterior inclination of articular eminence in control group was 65.60±6.04° 58.88±9.18° in control group, and 67.14±8.41°, 59.70±9.08° in patient group respectively. There was no significant correlation between two groups.

• The Journal of Advanced Prosthodontics
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• v.4 no.3
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• pp.153-157
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• 2012

PURPOSE. The study was conducted to compare the radiographic and clinical methods of measuring the horizontal condylar guidance (HCG) values. MATERIALS AND METHODS. The condylar guidance was measured using the radiographic (CT scan) and three clinical methods i.e. the wax protrusive records, Lucia jig record and intraoral central bearing device in 12 patients aged between 20-40 years irrespective of sex. The records were taken and transferred on the semi-adjustable articulator to record the HCG values. The CT scan was taken for 3D reconstruction of the mid facial region. Frankfort horizontal plane (FHP) and a line extending from the superior anterior most point on the glenoid fossa to the most convex point on the apex of articular eminence (AE) was marked on the CT scan. An angle between these two lines was measured on both right and left sides to obtain condylar inclination angle. Three interocclusal protrusive wax and jig records were taken and transferred to the semi adjustable articulator. Three readings were recorded on each side. Similarly the records were taken and transferred to the same articulator using the intra oral central bearing device to record the readings. RESULTS. The statistical analysis showed insignificant differences in the HCG values between the right and left sides [(P=.589 (CT), P=.928 (wax), P=.625 (jig), P=.886 (tracer)]. The clinical methods provided low Pearsons correlation values [(R = 0.423 (wax), R = 0.354 (jig), R = 0.265 (tracer)] for the right as well as the left sides when compared with the CT values. Among the clinical methods, jig and wax method showed strong level of association which is statistically significant while the intra-oral tracer showed weak association with the other two methods. CONCLUSION. The right and left HCG values were almost similar. The CT scan showed higher HCG values than the clinical methods and among the clinical methods, values obtained from all the methods were comparable.

• Imaging Science in Dentistry
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• v.46 no.2
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• pp.127-131
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• 2016

Purpose: This study was performed to compare the condylar position in patients with temporomandibular joint disorders (TMDs) and a normal group by using cone-beam computed tomography (CBCT). Materials and Methods: In the TMD group, 25 patients (5 men and 20 women) were randomly selected among the ones suffering from TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The control group consisted of 25 patients (8 men and 17 women) with normal temporomandibular joints (TMJs) who were referred to the radiology department in order to undergo CBCT scanning for implant treatment in the posterior maxilla. Linear measurements from the superior, anterior, and posterior joint spaces between the condyle and glenoid fossa were made through defined landmarks in the sagittal view. The inclination of articular eminence was also determined. Results: The mean anterior joint space was 2.3 mm in the normal group and 2.8 mm in the TMD group, respectively. The results showed that there was a significant correlation between the superior and posterior joint spaces in both the normal and TMD groups, but it was only in the TMD group that the correlation coefficient among the dimensions of anterior and superior spaces was significant. There was a significant correlation between the inclination of articular eminence and the size of the superior and posterior spaces in the normal group. Conclusion: The average dimension of the anterior joint space was different between the two groups. CBCT could be considered a useful diagnostic imaging modality for TMD patients.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.91-105
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• 2005

For af accurate diagnosis and treatment planning of facial asymmetry, the use of 3-dimensional (3-D) image is indispensable. The purpose of this study was to get standard data for the 3-D analysis of facial asymmetry Computerized tomography (CT) was taken in the 60 normal occlusion individuals (30 male. 30 female) who did not have any apparent facial asymmetry. The acquired 2D CT DICOM data were input on a computer, and the reformatted 3-D images were created using a 3-D image software. Twenty three measurements were established in order to evaluate asymmetry; 15 ;omear measurements (6 for ramus length. 1 for condylar neck length, and 8 for mandibular body length) and 8 angular measurements (4 for gonial angle. 2 for frontal ramal inclination. and 2 for lateral ramal inclination) The right aid left difference of each measurement was calculated and analyzed. It is suggested that the right and left differences of the measurements obtained from the study could be used as references for the diagnosis of facial asymmetric patients.

• The korean journal of orthodontics
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• v.47 no.5
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• pp.277-288
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• 2017

Objective: Treating Class II subdivision malocclusion with asymmetry has been a challenge for orthodontists because of the complicated characteristics of asymmetry. This study aimed to explore the characteristics of dental and skeletal asymmetry in Class II subdivision malocclusion, and to assess the relationship between the condyle-glenoid fossa and first molar. Methods: Cone-beam computed tomographic images of 32 patients with Class II subdivision malocclusion were three-dimensionally reconstructed using the Mimics software. Forty-five anatomic landmarks on the reconstructed structures were selected and 27 linear and angular measurements were performed. Paired-samples t-tests were used to compare the average differences between the Class I and Class II sides; Pearson correlation coefficient (r) was used for analyzing the linear association. Results: The faciolingual crown angulation of the mandibular first molar (p < 0.05), sagittal position of the maxillary and mandibular first molars (p < 0.01), condylar head height (p < 0.01), condylar process height (p < 0.05), and angle of the posterior wall of the articular tubercle and coronal position of the glenoid fossa (p < 0.01) were significantly different between the two sides. The morphology and position of the condyle-glenoid fossa significantly correlated with the three-dimensional changes in the first molar. Conclusions: Asymmetry in the sagittal position of the maxillary and mandibular first molars between the two sides and significant lingual inclination of the mandibular first molar on the Class II side were the dental characteristics of Class II subdivision malocclusion. Condylar morphology and glenoid fossa position asymmetries were the major components of skeletal asymmetry and were well correlated with the three-dimensional position of the first molar.

• Imaging Science in Dentistry
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• v.44 no.2
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• pp.95-102
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• 2014

Purpose: This study was performed to evaluate the reproducibility of panoramic radiographs of dentulous and edentulous patients. Materials and Methods: The reproducibility of panoramic radiographs was evaluated using the panoramic radiographs acquired from 30 anterior dentulous patients by using a common biting positioning device (dentulous group) and 30 anterior edentulous patients by using chin-support devices to take a panoramic radiograph (edentulous group), respectively; these patients had undergone 3 or more panoramic radiographs. The widths and angles between the designated landmarks were measured on the panoramic radiographs, and the reproducibility was evaluated using the intraclass correlation coefficient (ICC) and the coefficient of variation. Results: In the dentulous and edentulous groups, the ICCs of the mandibular ramus and mandibular angle areas were higher than the condylar head and zygomatic areas. The mandibular ramus and angle areas showed statistically lower mean coefficients of variation than the condylar head and zygomatic areas in the dentulous group. The mandibular angle area showed a significantly lower mean coefficient of variation than the zygomatic area in the edentulous group. By comparing the two groups, each ICC of the edentulous group was lower than that of the dentulous group, and the mean coefficients of variation of the mandibular ramus area, zygomatic area, left condylar inclination, and ramus ratio between the right and the left in the edentulous group were significantly higher than those in the dentulous group. Conclusion: Biting positioning for dentulous patients provided better positioning reproducibility than chin-support positioning when performing panoramic radiography for edentulous patients.

• The korean journal of orthodontics
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• v.45 no.3
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• pp.121-129
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• 2015

Objective: This study aimed to assess three-dimensional changes in the temporomandibular joint positions and mandibular dimensions after correction of dental factors restricting mandibular growth in patients with Class II division 1 or division 2 malocclusion in the pubertal growth period. Methods: This prospective clinical study included 14 patients each with Class II division 1 (group I) and Class II division 2 (group II) malocclusions. The quad-helix was used for maxillary expansion, while utility arches were used for intrusion (group I) or protrusion and intrusion (group II) of the maxillary incisors. After approximately 2 months of treatment, an adequate maxillary arch width and acceptable maxillary incisor inclination were obtained. The patients were followed for an average of 6 months. Intraoral and extraoral photographs, plaster models, and cone-beam computed tomography (CBCT) images were obtained before and after treatment. Lateral cephalometric and temporomandibular joint measurements were made from the CBCT images. Results: The mandibular dimensions increased in both groups, although mandibular positional changes were also found in group II. There were no differences in the condylar position within the mandibular fossa or the condylar dimensions. The mandibular fossa depth and condylar positions were symmetrical at treatment initiation and completion. Conclusions: Class II malocclusion can be partially corrected by achieving an ideal maxillary arch form, particularly in patients with Class II division 2 malocclusion. Restrictions of the mandible in the transverse or sagittal plane do not affect the temporomandibular joint positions in these patients because of the high adaptability of this joint.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.219-225
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• 1990

Panoramic radiography is convenient in clinic and visualizes those areas which other technique do not give. But the technique has limitation of image distortion which results from the relationship of the ramus to the focal trough and from the direction of the central ray. This study is, using 7 dry skulls, to determine the effect of rotation of patient's head on reducing those distortion and determine the magnification ratio of images of mandibular condyle in rotated patient head position. The obtained results were as follows: 1. Generally, in panoramic radiography the anterolateral portion of the mandibular condyle was best to be visualized. 2. There are no significant difference between the image readability of anteromedial portion and that of anterocentral portion of the mandibular condyle. 3. Anterolateral portion of the mandibular condyle was better visualized in rotated head position by 20 degree or horizontal condylar inclination than in conventional position or in rotated head position by 10 degree. 4. The magnification ratio of the anteroposterior diameter in the image of mandibular condyle was least in the rotated head position by horizontal inclination of the mandibular condyle and was largest by 20 degree.

• The korean journal of orthodontics
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• v.43 no.4
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• pp.168-177
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• 2013

Objective: In this study, we aimed to examine the relationship between chin deviation and the positional and morphological features of the mandible and to determine the factors that contributed to chin deviation in individuals with a unilateral cleft lip and palate (UCLP). Methods: Cone-beam computed tomography (CBCT) images of 28 adults with UCLP were analyzed in this study. Segmented three-dimensional temporomandibular fossa and mandible images were reconstructed, and angular, linear, and volumetric parameters were measured. Results: For all 28 individuals, the chin was found to deviate to the cleft side by 1.59 mm. Moreover, among these 28 individuals, only 7 showed distinct (more than 4 mm) chin deviation, which was toward the cleft side. Compared to the non-cleft side, the mandibular body length, frontal ramal inclination, and vertical position of the condyle were lower and inclination of the temporomandibular fossa was steeper on the cleft side. Furthermore, the differences in inclination of the temporomandibular fossa, mandibular body length, ramus length, and condylar volume ratio (non-deviated/deviated) were positively correlated with chin deviation. Conclusions: UCLP individuals show mild chin deviation to the cleft side. Statistical differences were noted in the parameters that represented positional and morphological asymmetries of the mandible and temporomandibular fossa; however, these differences were too small to indicate clinical significance.