• The Journal of Korean Academy of Prosthodontics
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• v.31 no.4
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• pp.565-579
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• 1993

This study was accomplished to analyse and compare the occlusal contact patterns during eccentric mandibular movements in adult with normal occlusion. 50 subjects(male 27, female 23), who had natural occlusion and no symptom of temporomandibular disorder, were selected. Teeth contact patterns during mandibular eccentric movements were recorded and the distribution of tooth contacts in maximum intercuspation analysed by T-scan system. And then, tooth contact numbers recored by T-scan and silicone bite registration at centric occlusion were analysed and compared. The results obtained were as follows : 1. Antero-posteriorly, the qualitative center of occlusal contacts in centric occlusion were in the first molar areas, but there was a slight deviation in left-right directions. Thus, distribution of occlusal contacts were not bilaterally symmetric. 2. During the mandibular movements from centric occlusal position to right lateral and left lateral directions, the frequency that maxillary canine joined in lateral guidance was relatively high, but pure canine protected occlusion or pure group function occlusion had small frequency. 3. During mandibular protrusive movement, one or more maxillary central incisors frequently joined in protrusive guidance. 4. During mandibular eccentric movements, working and balancing side premature contact was observered in relatively high frequency. 5. In centric occlusal position, the numbers of occlusal contacts recorded on T-scan were relatively smaller than on silicone bite registration.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.1
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• pp.55-68
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• 2007

The purpose of this study was to analyze the distribution of stress in the surrounding bone around implant placed in the first and second molar region. Two different three-dimensional finite element model were designed according to vertical bone level around fixture ($4.0mm{\times}11.5mm$) on the second molar region. A mandibular segment containing two implant-abutments and a two-unit bridge system was molded as a cancellous core surrounded by a 2mm cortical layer. The mesial and distal section planes of the model were not covered by cortical bone and were constrained in all directions at the nodes. Two vertical loads and oblique loads of 200 N were applied at the center of occlusal surface (load A) or at a position of 2mm apart buccally from the center (load B). Von-Mises stresses were analyzed in the supporting bone. The results were as follows; 1. With the vertical load at the center of occlusal surface, the stress pattern on the cortical and cancellous bones around the implant on model 1 and 2 was changed, while the stress pattern on the cancellous bone with oblique load was not. 2. With the vertical load at the center of occlusal surface, the maximum von-Mises stress appeared in the outer distal side of the cortical bone on Model 1 and 2, while the maximum von-Mises stress appeared in the distal and lingual distal side of the cortical bone with oblique load. 3. With the vertical load at a position of 2 mm apart buccally from the center, there was the distribution of stress on the upper portion of the implant-bone interface and the cortical bone except for the cancellous bone, while there was a distribution of stress on the cancellous bones at the apical and lingual sides around the fixture and on the cortical bone with oblique load. 4. With the changes of the supporting bone on the second molar area, the stress pattern on the upper part of the cortical bone between two implants was changed, while the stress pattern on the cancellous bone was not. The results of this study suggest that establishing the optimum occlusal contact considering the direction and position of the load from the standpoint of stress distribution of surrounding bone will be clinically useful.

• The Journal of the Korean dental association
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• v.51 no.5
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• pp.255-264
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• 2013

Many concept of occlusion have been introduced in the past, but there isn't any generally accepted unified theory since a single occlusion theory cannot represent the natural perfection, especially considering the difference in clinical experience, the dynamic occlusion, and individual diversity in mastication pattern. NAT(Naturgemasse Aufwachstechnik)/NFR((Natur Funktionsgerechte Rekonstruktion) occlusion is not just a theory on occlusion, but a clinical occlusion that can be practically applied to clinical practice by providing dynamic occlusion adjusted to the individual mastication pattern and biomechanics. This report aims to provide a guide to a clinically biomechanical occlusion through the teamwork of both the dentist and the lab technician by introducing the NAT occlusion through following: reviewing the concept of occlusion in terms of morphology, its correlation with NAT/NFR occlusion, reviewing the limitation of conventional occlusion theories, and introducing the clinical application of NAT/NFR.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.645-660
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• 1993

In this study, effects of incision of retrodiscal tissue and unilateral occlusal reduction on temporomandibular joint of rabbit were investigated. Twenty-seven adult New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study. Temporomandibular joint surgery was performed in left temporomandibular joint of 24 rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2mm posterior to the disc. They were divided into two groups : twelve were left untreated after surgery, occlusal reduction was performed on left posterior teeth every 2 weeks in the other twelve rabbits, The remaining three served as the control group. The sample were sacrificed by 8, 12, and 16 weeks after surgery. Histologic examinations were performed after sacrificing them. The results were as follows : 1. Histologic findings which were manifested by flat articular fossa, broad articular surface, generalized recession of articular cartilage and sclerosis of subchondral bone were observed. These findings were similar to internal derangement. 2. In the rabbits untreated after surgery, thin cartilagenous layer and necrotic tissue were observed in 8 weeks group, calcifying cartilagenous layer was observed in 12 weeks group, and cartilagenous layer on anterior portion was observed in 16 weeks group. So, it showed gradual healing pattern into the normal tissue except displaced disc. 3. Occlusal trauma after surgery resulted in generalized recession of upper and lower articular surface. Necrosis and vertical split on condylar process of mandible were observed in 8 weeks group. Osteoclasts, exposure of subchondral bone due to erosion on upper and lower articular surface, and degenerative changes on retrodiscal tissue were observed in 16 weeks group. So, it showed continuous prowess pattern of osteoarthrosis.

• Journal of Oral Medicine and Pain
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• v.41 no.4
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• pp.169-179
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• 2016

Purpose: This study is designed to analyse etiology and bone pattern at the first visit using cone-beam computed tomography (CBCT) and to evaluate the treatment outcome of conservative treatment in temporomandibular disorder (TMD) patients with rheumatoid arthritis (RA). Methods: One hundred condyles in 50 subjects with RA were chosen among the patients who presented to the Department of Oral Medicine of Pusan National University Dental Hospital, diagnosed as TMD. Condylar bone changes were classified by normal, erosive bony change, proliferative bony change and combined group (erosive bony change+proliferative bony change). They were treated conservatively with physical therapy, medication, behavioral therapy and/or occlusal stabilizing splint therapy. After 3 months on average, patients were re-evaluated with regards to subjective symptoms and the clinical findings were investigated. Results: TMD patients with RA have behavioral contributing factors such as parafunctional habit. The results that analyse bone pattern at the first visit using CBCT proliferative bony changes group (32.6%) were more common than erosive bony changes group (15.2%). In comparison between unilateral and bilateral bony change in temporomandibular joint, the ratio showed no significant differences. After 3 months of conservative treatments, pain, noise, limitation of motion (LOM) were markedly improved regardless of occlusal splint therapy. However only LOM was significantly improved through occlusal splint therapy during 3 months. Conclusions: TMD patients with RA had similar behavioral contributing factors and characteristics of CBCT images shown in general TMD patients and also similar response to conservative treatment so it is difficult to differentiate. Therefore when TMD patients show symptoms corresponding to clinical diagnostic criteria of RA at the first visit, serological testing should be conducted and through this, early diagnosis and treatment of RA should be initiated.

• 대한치과보철학회:학술대회논문집
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• 1998.11a
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• pp.21-21
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• 1998

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.175-182
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• 1990

This study was performed to investigate the influence of occlusal change on the masticatory muscle activity. 8 students without any symptom of T.M.J. dysfunction, any history of prosthodontic or orthodontic treatment on dental college of WonKwang Univ. were participated in this study. The activity of masseter and anterior temporal muscles were measured by bioelectric processor(EM2, Myotronics, Inc., U.S.A.) during voluntary maximal clenching on natural teeth, by splint with bilateral posterior surface contact, by splint with unilateral posterior surface contact, and by splint without unilateral posterior teeth contact. The obtained results were as follows ; 1. The loss of posterior contact on noe side resulted in change of the activity of anterior temporal and masseter muscle during clenching on ipsilateral side, but there was no change of muscle activity on contralateral side. 2. The activity of anterior temporal and masseter muscle during clenching were not affected by the pattern of occlusal contact. 3. There were no difference between the activity of anterior temporal and masseter miuscle during clenching by natural teeth and by occlusal splint.

• The korean journal of orthodontics
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• v.21 no.1 s.33
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• pp.185-195
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• 1991

This study was undertaken to grope the correlation of the maximal bite force and tooth-craniofacial structure. The maximal bite force of 76 adult male, aged 18-28 (mean aged: $23.4{\pm}2.2$) years, was estimated and cephalometric headplates were measured, tabulated and statistically analyzed. The results were as follows. 1. 59.61kg of bite force in first molar, 45.38kg in premolar and 17.10kg in central incisor were arranged. 2. The bite force was negatively correlated to genial angle, mandibular plane angle, the angle between occlusal plane and mandibular plane, the angle between palatal plane and mandibular plane, and positively correlated to posterior height of face, length of mandibular body, length of ramus, facial depth in craniofacial structure. 3. The group with strong bite force showed small genial angle, mandibular plane angle, the angle between occlusal plane and mandibular plane, the angle between palatal plane and mandibular plane, and long posterior height of face, length of mandibular body, length of ramus, facial depth. So they manifested the tendency to brachycephalic pattern, on the other hand, the group with weak bite force manifested the tendency to dolichocephalic pattern. 4. There is no correlationships between bite force and mesial inclination of premolar axis in this subject. 5. It is considered bite force have an effect upon craniofacial pattern, especially upon the lower face.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.1
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• pp.63-76
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• 1993

The purpose of this study was to investigate the disclusion time and occlusal pattern during lateral movement in normal group and temporomandibular dysfunction (TMD) group. Twenty dental college students of Chosun University without the abnormal occlusion and temporomandibular dysfunction were selected as a normal group, and twenty slight temporomandibular dysfunction (TMD) group and the ten moderate temporomandibular dysfunction (TMD) group classified according to Helkimo's dysfunction index were selected. Occlusal pattern was classified as canine guided occlusion, group functioned occlusion and the other group during lateral movement and disclusion time in lateral movement was measured using T-Scan system. The result were as follows: 1. The disclusion time according to each group were $1.24{\pm}0.58$ sec in normal $1.60{\pm}0.79$ sec in slight TMD group and $2.29{\pm}0.80$ sec in moderate TMD group. There was statistically significant between normal group and moderate TMD group(P<0.01), slight TMD group and moderate TMD group(P<0.05). 2. The distribution of occlusal pattern in normal group was 62.5% (25 side) in canine guided occlusion, 27.5% (15 side) in group functioned occlusion. 3. The distribution of occlusal pattern in slight TMD group was 45% (18side) in canine guided occlusion, 35% (14 side) in group functioned occlusion and 20% (8side) in others and that in moderate TMD group was 15% (3 side) in canine guided occlusion, 35% (7 side) in group funcconed occlusion and 50% (10 side) in other 4. The disclusion time in normal group was $1.05{\pm}0.59$ sec at canine guided occlusion and $1.53{\pm}0.72$ sec at group functioned occlusion. 5. The disclusion time in slight TMD group was $1.23{\pm}0.75$ sec in canine guided occlusion, $1.50{\pm}0.88$ sec in group functioned occlusion, and $2.61{\pm}0.57$ sec, in the other. There was staistically significant between canine guided occlusion and other(P<0.001)and group functioned occlusion and the other (P<0.05). 6. The disclusion time in moderate TMD group was $1.28{\pm}0.84$ sec in canine guided occlusion, $1.75{\pm}0.58$ sec in group functioned occlusion, and $2.98{\pm}0.08$ sec in the other(P<0.01).

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.43-57
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• 2005

Temporomandibular disorders have been defined as a collective term embracing a number of clinical problems that involve the temporomandibular joint, the masticatory nuscles, and associated structures. There have been many different contributing factors of TMDs which were traumatic, occlusal, pathophysiological and psychosocial. Among there factors, the effect of occlusion on TMDs have been a controversy for a long time. The purpose of this study was to investigate the effect of occlusal factors and oral habits on TMDs. In this study, 140 subjects with signs and symptoms of TMDs and diagnosed of TMD in the Orofacial Pain clinic of Yonsei University Dental Hospital though March to July 2004 were selected for the TMDs group and 50 subjects without any signs and symptoms of TMDs as the control group. The subjects were evaluated clinically in TMDs' Occlusal and Prosthodontic Restoration examinations. TMDs' examination was composed of the TMJ pain, sound, locking, temporal or masseter muscle palpation, mandibular movement, oral habits and headache. Occlusal examination was made of overjet, overbite, lost teeth number, nonfunctional interference, midline shift, then pattern of lateral movement and attrition. prosthodontic restoration examination had the existence of restoration, placement, then number of crown or bridge and Satisfiable index which estimated the quality of occlusal state of prosthodontic restorations. Following results were obtained : 1. The prevalence of TMDs was higher in their 20s & 30s, female of the TMD patients group. 2. The clenching frequency in the TMDs group(40.71%) was higher than those in the control group(18.00%), and there was a significant statistical difference(p<0.05). 3. The frequency of Nonfunctional interference in the TMDs group(10.00%) was higher than those in then Control group(2.00%), and there was a significant statistical difference(p<0.05). The result of this study indicated TMDs prevalence was higher in their 20s, 30s, female group of TMDs patients similar to the previous studies. Clenching and nonfunctional interference were estimated as the contributing factors of TMDs.