• The korean journal of orthodontics
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• v.31 no.5 s.88
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• pp.505-515
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• 2001

The purpose of this study was to measure the average tooth size of Korean with normal occlusion. According to the study, the average tooth ratios between the upper and lower teeth which could assure the proper ovebite, overjet and good interdigitation were calculated. The normal occluson sample of this study consisted of 43 Korean male adults and 51 Korean female adults. Among them, 22 Korean male adults and 51 Korean female adults were from KAO(Korean Association of Orthodontists), 21 Korean male adults were from Department of Orthodontics, College of Dentistry, Yonsei University. The results from this study were as follows : 1 The average tooth size of Korean Norm classified by male and female was measured. 2. The average tooth size of Korean male adults with normal occlusion was significantly larger than that of Korean female adults except upper and lower first molars. (p<0.05) 3. The tooth ratio which could Predict the proper overbite and overjet in anterior teeth and proper occlusion in posterior teeth was calculated. 1) Sum of inciosrs = 4:2.97 2) Neff's anterior coefficient = 1.22 3) Bolton's anterior ratio = 78.29%, overall ratio = 91.14% 4. A positive correlation was observed between the sum of lower anterior incisors and the sum of unilateral canine and premolars In each jaw. Based this correlation, the regression equation was made which could Predict the sum of unerupted unilateral canine and premolars in mired dentition. 1) Sum of unilateral unerupted upper canine and premolars' width = 10.435018 + 0.513346 ${\times}$ (sum or lower 4 incisors' width) 2) Sum of unilateral unerupted lower canine and premolars' width = 9.654002 + 0.502565 ${\times}$ (sum of lower 4 incisors' width)

• The korean journal of orthodontics
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• v.41 no.5
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• pp.324-336
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• 2011

Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.403-414
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• 1995

The purpose of this study was to investigate the histologic changes in mandibular periodontium during overbite closure for openbite treatment by continuous arch wires and anterior vertical elastics. Two female monkey(Macaca nemestrina) with permanent dentition were used. Posterior bite block was fixed to each of their maxillae, which made the animal temporary anterior openbite as well as stabilized the whole maxillary anchorage. In each mandible, all the teeth except the second molars which had been extracted, were prepared for cast crowns. 018 inch Standard brackets were welded on these crowns. After cementation, two types of the $016{\times}022$ inch continuous arch wires, the plain ideal arch to the control animal and the MEAW(multiloop edgewise archwire) to the other experimental one were inserted. Then anterior vertical elastics were applied for two weeks. The overbite depth changes in the monkeys and histologic examinations of the mandibular periodontiums suggested the following conclusions. 1. During two weeks of the experimental period, the overbite increased + 0.3 mm in the control and + 1.3 mm in the experimental one. 2. In both the control and the experimental animal, histologic examinations showed that incisors, canines and first premolars were subject to extrusive force and the rest of posteriors were subject to intrusive one. 3. In periodontiums of the extruded incisors of the experimental one, reorientation of the periodontal fiber structures reflected the direction of force and the alveolar bone surfaces including apical and crestal areas which had been subject to tension, were the front of new bone formation. 4. In periodontiums of the extruded incisors of the experimental one, neither excessive hyalinization nor gross root resorption was observed. 5. Alveolar bone remodeling of anteriors and posteriors was more remarkable in the experimental one than the control.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.683-690
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• 2020

The objective of this study was to analyze time-dependent changes in bite marks on pig skin. Bite marks produced by the average bite force of adults were analyzed three-dimensionally for 3 hours directly after its formation, at 1-hour intervals. The measured values were calculated by root mean square (RMS) and statistically analyzed by one-way ANOVA test (α = 0.05). The average bite sizes were 0.899 mm, 0.717 mm and 0.506 mm at the first, second and third intervals, respectively, and were significantly different between the three intervals (P < 0.05). A bite mark showed time-dependent changes in the compression level, showing the greatest change in the first interval. Changes in bite marks decreased over time, and bite marks were observed most prominently generated by the anterior dentition.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.12 no.2
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• pp.9-20
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• 1990

A series of 19 cases with maxillary hyperplasia and mandibular retrognathia were operated on by simultaneous superior repositioning of the maxilla after Le Fort I osteotomy and anterior repositioning of the mandible after bilateral sagittal split ramus osteotomies with or without osteotomy of the inferior border of the mandible. These were evaluated by retrospective cephalometric and computer analysis for the longitudinal skeletal and dental changes for an average of 17.1 months after surgery. For stabilization of the osteotomized segments, the authors used wire osteosynthesis by means of bilateral infraorbital and zygomatic buttress suspension wire at the maxilla, and direct interosseous wire at the split segments of the mandibular rami. Results show generally good stability after simultaneous maxillary and mandibular surgery with wire osteosynthesis, and a minimal to moderate tendency toward skeletal and dental relapse. This article is a preliminary study to defy the efficiency of the wire osteosynthesis (wo)compared with rigid internal fixation (RIF) for simultaneous maxillary and mandibular surgery. 1. The vertical relapse rate of the A point after superior repositioning of the maxilla is 2.2%. 2. The horizontal relapse rate of the B point after advancement of the mandible is 18.3%. 3. The condyle is distracted inferiorly and slightly posteriorly at the immediate postoperative period. 4. At the long term follow up examination, the condyle presents tendency of return to the preoperative position. 5. Condylar segment angle is decreased at the immediate postoperative period, and at the long term follow up evaluation, the angle is increased. 6. Gonial angle is increased at the immediate postoperative period, and then is decreased at the long term follow up evaluation. 7. The dentition is satisfactory with acceptable movement at the long term follow up evaluation. 8. At the mandibular free body analysis, genioplasty shows good stability. 9. Wire osteosynthesis provides excellent stabilization for the simultaneous maxillary and mandibular surgery.

• Journal of Periodontal and Implant Science
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• v.44 no.1
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• pp.8-12
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• 2014

Purpose: The aim of this retrospective chart review was to evaluate the four-year survival rate of a titanium implant system. Methods: A total of 352 sand-blasted, thermally acid-etched titanium implants were inserted into 181 partially or completely edentulous patients. Their cumulative survival rate was evaluated retrospectively. Associated factors, such as the implant distribution and treatment type were included in the evaluation. Results: The implants were equally distributed between the maxilla (52.3%) and the mandible (47.7%). 48 implants (13.6%) were placed in the anterior region and 304 implants (86.4%) in the posterior region. The majority of the implants were inserted into bone of type II and III quality (89.8%) and volume (quantity B and C, 87.2%). Most of the implants (70.7%) were restored as single crowns; 28.7% supported a bridge construction and 0.6% a full denture. Only one implant failed, resulting in a four-year cumulative survival rate of 99.7%. Conclusions: The implant system showed an excellent four-year survival rate. It proved to be a safe and predictable means for restoration of the dentition in partially or completely edentulous patients.

• The korean journal of orthodontics
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• v.13 no.1
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• pp.31-43
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• 1983

The following results were abtained based on the research of the occlusal patterns among 1074 handicapped persons (cerebral palsy: 46, mental subnormality: 619, deafmute: 285, blind: 111, childish autism:8, cleft lip and cleft palate:3, polimyelitis:2) of the age between 6 and 23 in Chollanamdo, Korea, in comparison with a normal group of 1048 children of the age between 6 and 15 selected at random in J primary school in Gwang-ju City. 1. According to Angle's malocclusion classification, all the handicapped groups, except the cerebral palsy and the blind, showed a higher prevalence of malocclusion than that of the normal. Especially the prevalence of Class II, devision 1 malocclusion in the cerebral palsy was the highest, and the prevalence of Class III malocclusion in all the handicapped groups was higher than that of the normal group. Among these groups the highest prevalence of Class III malocclusion was in the Down's syndrome group. 2. On the the abnormal pattern of the anterior region, there was no significant difference $(P\leqq0.05)$ between the normal and the cerebral palsy, the deafmute, and e blind. The open bite $(7.27{\pm}1.04\%)$ and the cross-bite $(32.7{\pm}6.33\%)$ of the Down's syndrome wire higher than that of the normal, and the forward position of the mandible could be recognized in the Down's syndrome group. 3. On the midline position of the dentition, all the handicapped showed the same percentage of deviation, but the degree of mandibular shift to the right $(20.00{\pm}5.39\%)$ or left $(10.91{\pm}4.20\%)$ was higher than that of the normal only in the Down's syndrome group. 4. On the abnormal pattern of the posterior region, the cross-bite of the Down's syndrome was higher than that of the normal by $20.00{\pm}5.39\%$, the cross-bite of the cerebral palsy and the cross-bite and the open bite of the mental subnormality were slightly higher than that of the normal. The other handicapped groups showed no significant difference $(P\leq0.05)$ to the normal.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.67-76
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• 2020

With the evolution of the computer-aided design/computer-aided manufacturing (CAD/CAM) technology, the intraoral scanners are playing an increasingly important role, as they are the first step towards a completely digital workflow. The CAD/CAM double scanning technique has been used to transfer the information from provisional restorations to definitive restorations. In this case, a 67-year-old male with esthetically compromised anterior teeth, generalized severe attrition of teeth, and reduced vertical dimension was treated with full mouth rehabilitation including a re-establishment of the lost vertical dimension of occlusion assisted by the crown lengthening procedure. The provisional restorations were fabricated using an intraoral scanner and the CAD/CAM double scanning technique. After the period of adaption, the definitive monolithic zirconia restorations were delivered. The CAD/CAM double scanning technique successfully transferred the occlusal and morphological characteristics, obtained from the provisional restorations, to the definitive restorations.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.42-47
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• 2014

Decrease of occlusal vertical dimension (OVD) due to loss of teeth structure and destruction of the occlusal plane by severely worn dentition may cause cross bite or temporomandibular joint disorder by following change of facial feature or the loss of anterior guidance. Full mouth rehabilitation via an increase of the OVD can be considered to avoid this problem and proper evaluation of patient's OVD is essential. An 80 year old male visited for overall prosthodontic treatment, cross bite due to continuous wear and following decrease of the OVD were observed. We analyzed the existing occlusal relationship using the diagnostic cast, the radiographic evaluation and clinical test, and then proper increase of OVD was selected. The new OVD on diagnostic wax up was placed by the temporary restoration. After 3 months of observation period, final restoration with fixed partial dentures and implant overdenture were made. Throughout the follow-up period of 8 months, the aesthetic and functional improvement can be obtained.

• The korean journal of orthodontics
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• v.50 no.4
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• pp.268-277
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• 2020

This case report demonstrates two different uprighting mechanics separately applied to mesially tipped mandibular first and second molars. The biomechanical considerations for application of these mechanisms are also discussed. For repositioning of the first molar, which was severely tipped and deeply impacted, a novel cantilever mechanics was used. The molar tube was bonded in the buccolingual direction to facilitate insertion of a cantilever from the buccal side. By twisting the distal end of the cantilever, sufficient uprighting moment was generated. The mesial end of the cantilever was hooked over the miniscrew placed between the canine and first premolar, which could prevent exertion of an intrusive force to the anterior portion of the dentition as a side effect. For repositioning of the second molar, an uprighting mechanics using a compression force with two step bends incorporated into a nickel-titanium archwire was employed. This generated an uprighting moment as well as a distal force acting on the tipped second molar to regain the lost space for the first molar and bring it into its normal position. This epoch-making uprighting mechanics could also minimize the extrusion of the molar, thereby preventing occlusal interference by increasing interocclusal clearance between the inferiorly placed two step bends and the antagonist tooth. Consequently, the two step bends could help prevent occlusal interference. After 2 years and 11 months of active treatment, a desirable Class I occlusion was successfully achieved without permanent tooth extraction.