• The Journal of Advanced Prosthodontics
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• 제13권1호
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• pp.36-45
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• 2021

Purpose. To investigate the fracture resistance of monolithic CAD-CAM all-ceramic surveyed crowns with two different occlusal rest seat designs. Materials and Methods. Two maxillary first premolar were prepared for all-ceramic surveyed crowns with wide (2/3rd of buccolingual width of an unprepared tooth) or narrow (1/3rd of buccolingual width of an unprepared tooth) disto-occlusal rest seat (ORS) designs. Eighty monolithic CAD-CAM all-ceramic surveyed crowns were prepared and divided into 4 groups - Group CR, Composite resin material as a control; Group LDS, Lithium disilicate based material; Group ZIPS, zirconia-material (IPS ZirCAD); and Group ZLHT, zirconia- material (CeramillZolidht+). Crowns were cemented on an epoxy resin die with adhesive resin cement. The fracture resistance of crowns was tested with the universal machine. Univariate regression analysis was used. Results. The mean ± standard deviation of maximum failure force values varied from 3476.10 ± 285.97 N for the narrow ORS subgroup of group ZIPS to 687.89 ± 167.63 N for the wide ORS subgroup of group CR. The mean ± standard deviation of maximum force was 1075 ± 77.0 N for group CR, 1309.3 ± 283.9 N for group LDS, 3476.1 ± 285.97 N for group ZIPS, and 2666.7 ± 228.21 N for group ZLHT, with narrow occlusal rest seat design. The results of the intergroup comparison showed significant differences in fracture strength with various material groups and occlusal rest seat designs (P<.001). Conclusion. The zirconia-based all-ceramic surveyed crowns fractured at more than double the load of Lithium disilicate based crowns. The crowns with narrow base occlusal rest seat design had statistically significantly higher fracture resistance than surveyed crowns with wide occlusal rest seat design. The use of narrow occlusal rest seat design in CAD-CAM all ceramic surveyed crowns provides higher fracture resistance, and therefore narrow occlusal rest design can be used for providing esthetics with high strength.

• The Journal of Advanced Prosthodontics
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• 제7권1호
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• pp.8-14
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• 2015

PURPOSE. To assess function by identifying changes in swallowing and masticatory performance in maxillary obturator prosthesis wearers. MATERIALS AND METHODS. Sixty subjects were recruited for the study, of which 20 were obturator wearers, 20 were completely dentulous and 20 had removable partial/complete dentures with similar Eichner's Index. Swallowing ability was evaluated with and without obturator using the "Water Drinking Test"; Masticatory performance was evaluated with the Sieve test; and maximum occlusal force was recorded with the help of a digital bite sensor. The data was analyzed using the Statistical Package for Social Science version 15.0 with a confidence level at 95%. RESULTS. Profile, behavior of drinking and time taken to drink were significantly improved (P<.001) in subjects after wearing obturator. Masticatory performance was not significantly different (P=.252) in obturator wearer when compared with dentulous or removable partial/complete denture wearer, but significantly (P<.001) high inter group difference in maximum occlusal force existed. Correlation between masticatory performance and maximum occlusal force was not significant (P=.124). CONCLUSION. Swallowing ability was significantly improved after wearing obturator but masticatory performance was not significantly different from those having similar occlusal support zone in their dentition.

• 대한치과교정학회지
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• 제48권5호
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• pp.339-345
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• 2018

Objective: The purpose of this study was to clarify the effects of continuous force application for extrusive tipping movement and occlusal interference on periapical root resorption in the rat mandibular first molar. Methods: We constructed an appliance comprising a titanium screw implant with a cobalt-chromium post as the anchorage unit and a nickel-titanium closed coil spring (50 cN) as the active unit. Force was applied on the mandibular left first molar of rats for 8 (n = 10) and 15 days (n = 10; experimental groups), with the tooth in occlusion. Five rats were included as a non-treated control group to examine the body effect of the appliance. Active root resorption lacunae, identified using tartrate-resistant acid phosphatase, were evaluated in terms of the length, depth, and area. Results: The rat mandibular first molars were mesially tipped and extruded in the occlusal direction. This mesio-occlusal tipping movement and occlusion resulted in the formation of a compression zone and active root resorption lacunae in the distoapical third of the distal roots. However, there was no significant difference in the amount of root resorption between the two experimental groups. The control group did not exhibit any active root resorption lacunae. Conclusions: Periapical root resorption was induced by continuous extrusive tipping force and occlusal interference in rat mandibular molars. These data suggest that we orthodontists had better take care not to induce occlusal interference during our orthodontic treatment.

• 구강회복응용과학지
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• 제35권3호
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• pp.153-159
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• 2019

목적: 구개측 굴곡파절이 있는 상악 구치의 교합면 마모 양상을 분석하여, 교합력과 굴곡파절의 연관성에 대해 연구해보고자 한다. 연구 재료 및 방법: 상악 구치에서 구개측 굴곡파절을 가지고 있는 148명의 환자, 총 308개의 치아를 대상으로 조사를 진행하였다. 구개측 굴곡파절을 가지고 있는 상악 소구치와 대구치의 교합면 마모를 분류 및 기록하였다. 치아별, 연령별, 성별에 따라 분류를 진행하였고, 그룹간의 통계적 유의성을 평가하기 위해 Chi-square test를 시행하였다(${\alpha}=0.05$). 결과: 상악 구치에서 구개측 굴곡파절은 제1대구치에서 가장 높은 빈도로 관찰되었고, 구개측 굴곡파절이 있는 모든 치아에서 하나 이상의 교합면 마모가 관찰되었다. 치아별, 연령별, 성별 모두에서 구개측 굴곡파절이 있는 치아의 교합면 마모는 교두 내사면과 중심와 및 변연융선에서 높은 빈도로 관찰되었으며 통계적으로 유의성이 있었다(P < 0.05). 결론: 구개측 굴곡파절은 상악 제1대구치에서 가장 많은 빈도로 관찰되었고, 구개측 굴곡파절이 관찰된 상악 구치 모두에서 교합면 마모가 관찰되었다. 그리고 교합면 마모는 교두 내사면과 중심와 및 변연융선에서 많은 빈도로 관찰되었다. 이와 같은 결과는 굴곡파절이 교합력과 연관이 있음을 보여준다.

• 한국전산구조공학회논문집
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• 제29권4호
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• pp.309-315
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• 2016

최근 치의학 분야에서도 인체에 대한 구조적이고 역학적인 이해를 위하여 유한요소해석 기법이 널리 사용되고 있다. 따라서 본 연구에서는 CT 이미지를 기반으로 하는 유한요소모델링 기법을 제안하고, 실험결과와 비교하여 검증하였다. 또한 제안된 해석기법을 통해 교합 시뮬레이션을 구현하여 정상 I급 교합과 Full-CUSP II급 교합상태의 두개골 모델에 대하여 기하비선형구조해석을 수행하였다. 그 결과, 하악골이 같은 거리만큼 이동할 때 사람의 실제 교합력 범위에서는 두 모델의 교합력에 큰 차이가 없는 것으로 나타났다. 그러나 응력분포를 비교했을 때 정상 I급 교합모델은 치아 및 치조골 전반에 응력이 균등하게 발생하는 반면, Full-CUSP II급 교합모델의 경우 일부 구역에 응력집중 현상이 나타났다. 이는 치아의 부재 및 재배열로 인하여 교합면이 달라지면서 생긴 결과라고 분석된다.

• 대한치과의사협회지
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• 제53권6호
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• pp.402-410
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• 2015

The aims of occlusal adjustment are as follows: to eliminate occlusal interference, to redirect force generated during function to which is favorable for teeth, to improve mastication efficiency and simultaneously establish stable maximal intercuspation or centric occlusion. Also, it should permit mandible to move freely from all positions. The sequence of occlusal adjustment in natural teeth and fixed prosthesis shall be as follows: 1) Eliminate interference that prevent optimal intercuspation and recontouring adjustment 2) Establish maximal intercuspation 3) Eliminate interference in lateral mandibular movement 4) Eliminate interference in anterior mandibular movement 5) Refine occlusal relationships.

• Journal of Oral Medicine and Pain
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• 제32권1호
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• pp.105-111
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• 2007

측두하악장애가 교합접촉 양상에 영향을 주는지에 관해 오랫동안 연구가 계속되어 왔으나 아직 명확한 결론을 내리지 못하고 있다. 본 연구의 목적은 편측성 측두하악장애 환자에서 증상측과 무증상측 사이의 교합접촉 양상을 비교하고 치료 전후 변화를 평가하고자 하였다. 단국대학교 치과대학부속병원 구강내과에 내원한 측두하악장애 환자 중 편측 증상만을 가진 환자 36명을 대상으로 T-Scan II system (Tekscan, INC., USA)을 사용하여 치료 전후의 교합접촉 양상을 평가하였다(남:녀=7:29, 평균 $29.2{\pm}14.8$세). 좌우측의 접촉점 수(number of contact point), 접촉력(contact force), 상대적 접촉력(relative contact force, %)을 조사하여 치료 전후의 좌우 균형성을 비교하였다. 연구 결과, 치료 전 환자의 증상측은 무증상측에 비해 접촉점 수와 접촉력이 감소되었으나(접촉점 수: p=0.056, 접촉력: p=0.060), 치료 후에는 증가되어 양측간에 차이를 보이지 않았다. 증상측의 접촉점 수와 접촉력이 치료 전후에 차이를 보인 반면(접촉점 수: p=0.038, 접촉력: p=0.052), 비이환측은 치료에 따른 유의한 변화를 보이지 않았다. 악궁 내 좌우 균형성을 평가하는 상대적 접촉력의 차이를 비교했을 때, 치료 전 양측간 차이가 약 27%였다가 치료 후에 약 12%로 유의하게 감소되었다(p=0.001). 이와 같은 결과로 볼 때, 편측성 측두하악장애 환자에서는 교합접촉 양상의 좌우불균형을 보이지만, 보존적 치료 후에 그 차이가 현저하게 감소되어 보다 대칭적이고 균형적인 교합을 회복하며 접촉점 수와 접촉력이 증가하는 것으로 생각된다.

• Journal of Oral Medicine and Pain
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• 제21권2호
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• pp.293-304
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• 1996

The purpose of this study was to investigate the peak electromyographic activity(EMG) and time intervals in firing sequence of Anterior temporalis(TA) and Masseter(MM) on clenching, the number of tender points in the head and neck muscles, the occlusal contact state on clenching, and their relationship. 78 patients with Temporomandibular Disorders(TMDs) participated and were classified into articular or muscular group by clinical signs and symptoms. BioEMG$\textregistered$ of integrated masticatory function analyzer, Biopak$\textregistered$ system(Bioresearch Inc., USA), was used to measure EMG and related items, and T- Scan$\textregistered$(Tekscan, USA), computerized occlusal analyser, was used to record occlusal contact state on maximum voluntary clenching. EMG and occlusal contact were synchronously recorded and analysed with SAS Statistical program. The results of this study were as follows : 1. In total subjects, EMG of TA was lower than that of MM in articular group but in muscular group, vice versa, As a result, the ratio TA to MM was significantly different between the two groups. no significant differece. 3. The number and force of occlusal contact were more in articular group, but there was no significant difference in Total Left-Right statistics(TLR) between the two groups. 4. In unilaterally affected subjects for muscle function, no significant difference was observed between the affected side and the contralateral side in articular group, but in muscular group, the item of the number of tender points showed significant difference. However, for occlusal contact items, contact force in articular group shows significant difference between the two sides. 5. Rate of coincidence of the first firing side of TA with affected side or preferred chewing side was higher and not different between the two groups, but no significant correlation was showed between the first firing side and the first occlusal contact side.

• 대한치과보철학회지
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• 제29권1호
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• pp.23-37
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• 1991

The understanding the natureof occlusal tooth contacts of natural dentition is important for correct diagnosis and treatment of diseases developed in stomatognatic system. Several investigator have studied the distribution of tooth contacts in maximum intercuspation and have reported contact locations with respect to the tooth position. Many methods have been clinically applied for the occlusal analysis in the intercuspal position. However, there are few quantative methods. This study analyzed the new software version of the T-Scan system to record and analyze occlusal contact balance in the anterior-posterior and right-left directions. Six time moment statistics and five moment statistics were calculated in the midsagittal and the incisal axes of the occlusal plane. In the present study, informed consent was obtained from 100 subjects with natural dentitions. The results were as follows ; 1. The mean of the dental arch length & width were 48.78, 65.32mm in whole population, 49.09mm, 65.50mm in males, 48.78mm, 64.63mm in females, respectively. 2. The mean of TLR & PLR were 0.193mm(left), 0.311mm(left), respectively. Therefore, the distribution of tooth contacts was bilaterally symmetric. 3. The mean of TFB & PFB were 29.168mm, 29.055mm, and that of LFB & RFB were 29.627mm, 29.587mm, respectively, and the qualitative center of occlusal contacts was the firtst molar. 4. The mean of LL & RL were 31.666mm, 31.377mm, respectively, and the quantitative center of occlusal force was the first molar. 5. The mean of LF & RF were 60.237N, 59.276N, respectively and Left-right moment was 72.491Nmm. Therfore, the distribution of occlusal force was bilaterally balanced.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제14권4호
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• pp.327-339
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• 1992

This study was undertaken to investigate the effect of orthognathic surgery on occlusal force. The maximum bite force was measured in 26 dentofacial deformity patients, aged 14-26(mean age 20.3) years, before surgery and at IMF removal, 3, 6, and 12months postsurgery. To grope the correlation of bite force and skeletal change after orthognathic surgery, the cephalometric headplates were measured, tabulated and statistically analyzed. The results were as follows. 1. The presurgical maximum bite force was 13.7kg in upper first molar(rt. Side 12.7kg, it. Side 14.6kg). There was remarkable difference with that of normal occlusion. 2. The recovery of bite force was very significant in according to the operation method and the duration of IMF that was 7.6kg at IMF removal, 14.2kg at 3 months, 19.7kg at 6 months. 26.1kg at 12 months postsurgery. 3. To fasten the recovery and to increase the bite force after orthognathic surgery, the long IMF time and the injury to the masticatory muscle should be avoided by the internal rigid fixation and early physical exercise. 4. The bite force was positively correlated to the changes of mandibular plane angle, the angle between platatal plane and mandibular plan, the angle between occlusal plane and mandibular plane, and negatively correlated to the changes of mandibular body length in craniofacial structure. 5. There was no correlationship between bit force and mesial inclination of tooth long axis of first molar in this subject. 6. There was no correlation between the changes of bite force and the changes of mechanical advantage of the temporal and masseter muscle.