• The Journal of the Korean dental association
• /
• v.21 no.12 s.175
• /
• pp.985-990
• /
• 1983

320 cephalometric roentgenograms of 25 boys and 15 girls which was longitudinally taken from the age 6.5 to 13.5 have been analyzed to access the angular growth changes of the mandible. The statistical analysis of the results allowed the following conclusions. 1. Gonial angle was reduced with ageing. 2. Chin angle was reduced with ageing. 3. Occlusal plane to mandibular plane angle was relatively stable. 4. Lower incisor to occlusal plane angle was reduced and showed the greatest variability.

• The korean journal of orthodontics
• /
• v.44 no.5
• /
• pp.263-267
• /
• 2014

Objective: To three-dimensionally elucidate the effects of occlusal hypofunction on the periodontal ligament and alveolar bone proper of rat molars by micro-computed tomography (micro-CT). Methods: Occlusal function in the molar area was restricted by attaching an anterior bite plate on the maxillary incisors and a metal cap on the mandibular incisors of 5-week-old male Wistar rats for 1 week. The periodontal ligament space and alveolar bone proper around roots of the mandibular first molar were assessed by histology and micro-CT. Results: The periodontal ligament space was narrower and the alveolar bone proper was sparser and less continuous in the hypofunction group than in the control group. Further, both the volume of the periodontal ligament and the volumetric ratio of the alveolar bone proper to the total tissue in the region of interest were significantly lower in the hypofunction group (p < 0.05). Conclusions: Occlusal hypofunction induces atrophic changes in the periodontal ligament and alveolar bone proper of rat molars.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.1
• /
• pp.70-76
• /
• 2018

Excessive tooth wear can lead to decrease in occlusal vertical dimension and can cause pathological changes in the oral environment and masticatory system. When recovering occlusal vertical dimension and occlusion, accurate diagnosis and analysis are essential. This clinical case describes a 75-year-old woman with severely worn dentition due to loss of the posterior support. Full mouth rehabilitation with occlusal vertical dimension increment was planned. Clinical and radiographic examinations, occlusal vertical dimension evaluation, and diagnostic wax-up were performed and patient adaptability was evaluated using provisional restorations. As for definitive restoration, considering economic condition of the patient, removable partial denture was fabricated and solitary implants were placed in the mandibular left and right posterior region to increase support and retention of the removable partial denture. During one year of follow-up, functional and esthetic outcomes were observed satisfactory.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.23 no.1
• /
• pp.11-19
• /
• 2007

There are have been reports that the distribution of electromyographical(EMG) activity is determined in a predictable manner by both the location and number of occlusal contacts. However, these reports placed an emphasis on whole dentition. Inclined plane contacts in the frontal plane are classified as A-, B- or C-types. Objectives: The aim of this study was to evaluate the relation between occlusal tooth contact patterns and EMG activity of masseter muscle during maximum voluntary clenching. Methods: Fifteen healthy human subjects(Mean age; 25.3 years) volunteered to participate in this study. Acrylic resin overlays were fabricated for upper 2nd premolars and 1st molars bilaterally, and offered 3 types(A-, B- and AB- type contact). EMG activity of the masseter muscles was recorded bilaterally during maximum voluntary clenching. Statistical analysis was performed using the one-way ANOVA. Results: The group with a A-type contact showed a statistically lower EMG activity of masseter muscle than that of natural group(p<0.05) and that of B- and AB- type groups(p<0.01) on both upper 2nd premolars and upper 1st molars. Conclusions: These results suggest that occlusal tooth contact patterns have an influence on EMG activity of masseter muscle during maximum voluntary clenching.

• The korean journal of orthodontics
• /
• v.42 no.4
• /
• pp.182-189
• /
• 2012

Objective: The aims of this study were to use a 3-dimensional (3D) system to compare molar relationship assessments performed from the buccal and lingual aspects, and to measure differences in occlusal contact areas between Class II and Class I molar relationships. Methods: Study casts (232 pairs from 232 subjects, yielding a total of 380 sides) were evaluated from both the buccal and lingual aspects, so that molar relationships could be classified according to the scheme devised by Liu and Melsen. Occlusal contact areas were quantified using 3D digital models, which were generated through surface scanning of the study casts. Results: A cusp-to-central fossa relationship was observed from the lingual aspect in the majority of cases classified from the buccal aspect as Class I (89.6%) or mild Class II (86.7%). However, severe Class II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. Mean occlusal contact areas were similar in the Class I and mild Class II groups, while the severe Class II group had significantly lower values than either of the other 2 groups (p < 0.05). Conclusions: Buccal and lingual assessments of molar relationships were not always consistent. Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect.

• The Journal of Advanced Prosthodontics
• /
• v.5 no.4
• /
• pp.388-395
• /
• 2013

PURPOSE. The purpose of this study was to estimate the effects of occlusal stability to identify action mechanisms of mouthguards, known to have a modulatory effect on limb muscle function. MATERIALS AND METHODS. This study included 20 male subjects to perform the isokinetic muscle tests and the Wingate anaerobic power test on both knee joints under five closed-mouth conditions: without or with 4 types of mouthguards with thickness of 2 mm based on premolar area: (1) full-coverage, (2) anterior partial-coverage, (3) right posterior partial-coverage, and (4) left posterior partial-coverage. The obtained results were subjected to One-way ANOVA with repeated measures, followed by post hoc test of the contrast method (${\alpha}$=.05). RESULTS. There was no significant difference between the closed position with and without a full-coverage mouthguard in all variables. However, significant differences were observed between with and without a partial-coverage mouthguard in muscular endurance during extension of the left knee, muscular power and endurance during flexion of the right knee. Additionally, significant differences were found between occlusal states with full- and partial-coverage mouthguards in muscular power and endurance during extension of the left knee. CONCLUSION. These findings indicate the elevation of vertical dimension by 2 mm or the inducement of occlusal stability had little effect on isokinetic muscle strength and anaerobic performance, while uneven distribution of occlusal force might have some positive effects.

• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.2
• /
• pp.121-129
• /
• 2020

From the point of view of oral rehabilitation, the treatment of extensive tooth wear requires a prosthetic approach. Physiological tooth wear is considered as a normal process and generally does not require treatment, but excessive tooth wear causes problems like inadequate occlusion and esthetics. Changes of occlusal vertical dimension should be made through accurate diagnosis and analysis. Also, the patient's adaptation to the changed occlusal vertical dimension should be assessed over time. This case was a 60-year-old male patient who complained of a decrease in chewing function and esthetics due to severe tooth wear. Full-mouth rehabilitation was performed with a tooth supported fixed prosthesis. An occlusal stabilization splint and provisional restoration were used to evaluate the adaptation to increased occlusal vertical dimension and induce a stable centric relation position. After that, monolithic zirconia prosthesis was delivered. We report this as a satisfactory functional recovery and esthetics.

• The korean journal of orthodontics
• /
• v.45 no.3
• /
• pp.113-120
• /
• 2015

Objective: This study compared occlusal contact areas of ideally planned set-up and accomplished final models against the initial in class I and II molar relationships at finishing. Methods: Evaluations were performed for 41 post-orthodontic treatment cases, of which 22 were clinically diagnosed as class I and the remainder were diagnosed as full cusp class II. Class I cases had four first premolars extracted, while class II cases had maxillary first premolars extracted. Occlusal contact areas were measured using a three-dimensional scanner and RapidForm 2004. Independent t-tests were used to validate comparison values between class I and II finishings. Repeated measures analysis of variance was used to compare initial, set up, and final models. Results: Molars from cases in the class I finishing for the set-up model showed significantly greater contact areas than those from class II finishing (p < 0.05). The final model class I finishing showed significantly larger contact areas for the second molars (p < 0.05). The first molars of the class I finishing for the final model showed a tendency to have larger contact areas than those of class II finishing, although the difference was not statistically significant (p = 0.078). Conclusions: In set-up models, posterior occlusal contact was better in class I than in class II finishing. In final models, class I finishing tended to have larger occlusal contact areas than class II finishing.

• The Journal of Advanced Prosthodontics
• /
• v.16 no.1
• /
• pp.57-65
• /
• 2024

PURPOSE. The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques. MATERIALS AND METHODS. The study included 31 inlays for prosthodontics purposes of 31 patients: 15 based on intraoral digital impressions (DI group); and 16 based on a conventional impression technique (CI group). Inlays included occlusal and a non-occlusal surface. Inlays were milled in ceramic. The inlay-teeth interface was replicated by placing each inlay in its corresponding uncemented clinical preparation and taking interface impressions with silicone material from occlusal and free surfaces. Interface analysis was made using white light confocal microscopy (WLCM) (scanning area: 694 × 510 ㎛²) from the impression samples. The gap size and the inlay overextension were measured from the microscopy topographies. For analytical purposes (i.e., 95-%-confidence intervals calculations and P-value calculations), the procedure REGRESS in SUDAAN was used to account for clustering (i.e., multiple measurements). For p-value calculation, the log transformation of the dependent variables was used to normalize the distributions. RESULTS. Marginal fit values for occlusal and free surfaces were affected by the type of impression. There were no differences between surfaces (occlusal vs. free). Gap obtained for DI group was 164 ± 84 ㎛ and that for CI group was 209 ± 104 ㎛, and there were statistical differences between them (p = .041). Mean overextension values were 60 ± 59 ㎛ for DI group and 67 ± 73 ㎛ for CI group, and there were no differences between then (p = .553). CONCLUSION. Digital impression achieved inlays with higher clinical marginal fit and performed better than the conventional silicone materials.

• The korean journal of orthodontics
• /
• v.23 no.4 s.43
• /
• pp.565-606
• /
• 1993

The purpose of this study was to evaluate the change of before and after treatment of anterior openbite malocclusions treated by Multiloop Edgewise Archwire technique. The openbite sample consisted of 4 male and 12 female adults, treated with nonextraction or third molar extraction. The normal sample consisted of 58 subjects, which have pleasing facial profile and normal occlusion and no experience of orthodontic or prosthodontic treatment. The 58 subjects of normal sample were subdivided by cephalemetric vertical relationship of face. The 40 subjects, cephalometric vertical relationship of face was in normal range, classified as Normal Sample group 1. The 18 subjects, increased cephalometric vertical relationship of face, classified as Normal Sample group 2. The computerized cephalometric analysis was accomplished with 50 reference points for 22 skeletal measurements, 46 dentoalveolar measurements, 8 soft tissue measurements. Statistical analysis of the data was carried out with paired t-test, Student's t-test, and DUNCAN test using SAS(PC version), The results were as follows : 1. There were no statistically significant differences in skeletal measurement between before and after treatment. The major changes were in dentoalveolar region. 2. After treatment, the long axis of maxillary and mandibular posterior teeth were distally tipped-back, and uprighted to bisected occlusal plane. The interincisal angle was increased. 3. There were no statistically significant increase in the upper posterior dental height and statistically significant decrease in the lower posterior dental height. The upper anterior dental height was increased, but there was no statistically significant increase in the absolute upper anterior dental hight. The lower anterior dental height was increased. 4. After treatment, the maxillary occlusal plane to palatal plane angle and the mandibular occlusal plane to mandibular plane angle were statistically significant increased. Then, there were no statistically significant difference between after treatment group and normal sample group 2. 5. After treatment, the percentage of upper lip length to upper anterior dental height was decreased. Then, There were no statistically significant difference between after treatment group and normal sample group 2.