• The Journal of Advanced Prosthodontics
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• 제12권5호
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• pp.283-290
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• 2020

PURPOSE. The present study aimed to evaluate the clinical applicability of monolithic zirconia (MZ) crowns of different thickness via determination of fracture resistance and marginal fit. MATERIALS AND METHODS. MZ crowns with 0.5, 0.8, 1.0, and 1.5 mm thickness and porcelain fused to metal (PFM) crowns were prepared, ten crowns in each group. Marginal gaps of the crowns were measured. All crowns were aged with thermal cycling (5 - 55℃/10000 cycle) and chewing simulator (50 N/1 Hz/lateral movement: 2 mm, mouth opening: 2 mm/240000 cycles). After aging, fracture resistance of crowns was determined. Statistical analysis was performed with one-way ANOVA and Tukey's HDS post hoc test. RESULTS. Fracture loads were higher in the PFM and 1 mm MZ crowns compared to 0.5 mm and 0.8 mm crowns. 1.5 mm MZ crowns were not broken even with the highest force applied (10 kN). All marginal gap values were below 86 ㎛ even in the PFM crowns, and PFM crowns had a higher marginal gap than the MZ crowns. CONCLUSION. The monolithic zirconia exhibited high fracture resistance and good marginal fit even with the 0.5 mm thickness, which might be used with reduced occlusal thickness and be beneficial in challengingly narrow interocclusal space.

• 대한치과보철학회지
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• 제37권1호
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• pp.23-41
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• 1999

During the previous several decades the osseointegrated implants have been considered as the most ideal therapy for the fully edentulous or partially edentulous patients. Although the research on the biocompatibility of osseointegration, the oral tactile function, and the histo-neurologic study had been performed, the change of the oral tactile sensibility and maximal occlusal force according to the postinsertion time of implant prostheses has not been studied. The purpose of this study was to compare the oral tactile sensibility and maximal occlusal force of implant pros-theses to natural teeth according to the specific postinsertion time intervals. The fifty seven patients treated with $Br{\aa}nemark$ implants during the recent seven years were involved in this study. The oral tactile sensibility and maximal occlusal force were measured according to the postinsertion time (${\leqq}6\;months,\;{\leqq}12\;{\leqq}\;18\;months\;{\leqq}\;24\;months,\;and\;{\geqq}20\;months$) 1. The passive tactile threshold of implants was higher than 6-7 times when comparing to natural teeth(P<0.05) 2. The absolute pressure threshold in horizontal and vertical direction for the passive tactile sensibility had decreased significantly in the post insertion time 13-18 months group and had increased significantly in the post insertion time over 25 months group (P<0.05) 3. 50% limit thickness and 100% absolute thickness for the active tactile sensibility had decreased significantly in the postinsertion time 7-12 months group ($AT_{50}:P<0.005,\;AT_{100}:P<0.05$) 4. The maximal occlusal force of the implants prostheses had decreased when comparing with natural teeth in the postinsertion time 1-6 months group(P<0.05) and after that there was no significant difference between the implant prostheses and natural teeth(P<0.05) 5. Maximal occlusal force according to the postinsertion time had increased significantly in the 13-18 months group (P<0.05) after that there was no significant difference. 6. There was positive correlation between age and oral tactile sensibility tested in horizontal and vertical direction ($P_{H:r}=0.39,\;P_{v:r}=0.41$) and there was no correlation between age and maximal occlusal force, age and active tactile sensibility 7. According to the results or the questionnaire, 76.6% of the patients were satisfied with the function and 96.7% of the patients were satisfied with the sensibility. In conclusion oral tactile sensibility and maximal occlusal force of implants have changed with the postinsertion time. Oral tactile function of implants was lower than that of the natural teeth, but for the maximal occlusal force there was no difference between implants and natural teeth.

• 대한치과보철학회지
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• 제51권3호
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• pp.160-166
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• 2013

연구 목적: 본 연구의 목적은 전통적인 금속도재관과 완전 지르코니아 크라운의 교합면 두께에 따른 파절강도를 비교하는 것이다. 연구 재료 및 방법: 하악 제1대구치에 해당하는 레진치를 교합면 1.5 mm, 변연은 1.0 mm 폭의 rounded shoulder로 하고 축면 경사각이 $6^{\circ}$가 되도록 삭제하여 금속 다이 64개를 제작하였다. 완전 지르코니아 크라운은ZIRKONZAHN CAD/CAM을 이용하여 Prettau zirconia blanks를 절삭하여 48개의 크라운을 제작하고 교합면 교두정의 두께에 따라 6개 군으로 분류하였다(0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm). 16개의 금속도재관을 제작하여 교합면 교두정 도재의 두께에 따라 2개 군으로 분류하였다(1.0 mm, 1.5 mm). 완성된 완전 지르코니아 크라운과 금속도재관은 만능시험기 상에서 치아 교합면에 수직으로 하중이 가하도록 하여 파절강도를 측정하였다. One-way ANOVA, Tukey multiple comparison test (${\alpha}=.05$)와 t-test (${\alpha}=.05$)로 검정하였다. 결과: 본 연구의 결과는 다음과 같다. 1. 실험 1군은 가장 낮은 값(646.48 N)을 나타내었고(P<.05), 실험 2, 3, 4, 5군은 교합면의 두께가 증가할수록 파절강도는 증가하였지만 (866.40 N, 978.82 N, 1196.82 N, 1222.41 N) 통계적으로 유의한 차이를 나타내지 않았다(P>.05). 실험 6군은 다른 군보다 통계적으로 유의하게 가장 높은 값(1781.24 N)을 나타내었다(P<.05). 2. 대조군의 파절강도는 도재의 두께가 1.0 mm와 1.5 mm일때각각2515.71 N, 3473.31 N이며 이는 통계적으로 유의한 차이를 나타내지 않았다(P>.05). 결론: 완전 지르코니아 크라운은 대구치부에서 최대교합력보다 높은 파절강도를 갖기 위해서는 1.0 mm이상의 두께가 필요하다.

• 대한치과보철학회지
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• 제30권3호
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• pp.437-443
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• 1992

This study was performed to investigate the availability of adhesive resin cement for luting agent of cast crown. The resin cements used in this study were Panavia-Ex(Kuraray Co., Japan) and C & B-Metabond (Parkell Bio-Materials U.S.A.). Zinc phosphate cement was Flecks zinc cement(Mizzy Inc., U.S.A.) The film thickness of cast crown at gingival margin, lateral wall and occlusal surface was observed with measuring microscope(Modek MXT 70 Matsuzawa Seiki Co., Japan) and the retention of cast crown was measured with Instron Universal Test Machine (Instron Engineering Co., U.S.A.) The results were as follows : 1. The value of retention of cast crown was the highest in the use of Panavia-EX, followed by C & B-Metabond and 2inc phosphate cement, respectively. 2. There was no difference in film thickness among the three cements, but the film thickness in all cements was highest at occlusal surface.

• 대한치과보철학회지
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• 제60권2호
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• pp.135-142
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• 2022

목적: 이번 연구의 목적은 단일구조 지르코니아(monolithic zirconia) 크라운의 서로 다른 부위에서, 감소된 지르코니아의 두께가 파절 저항성에 미치는 복합적인 영향을 평가하기 위한 것이다. 재료 및 방법: 실험을 위해 7개의 니켈-크롬 다이를 제작하였다. 다이는 하악 제 1대구치를 치아 형성한 지대치 3D 모델을 바탕으로 제작되었다. 지대치는 1.5 mm 교합면 삭제를 시행하였고, 변연은 1.0 mm의 deep chamfer로 형성하였다. 이 지대치 형태를 바탕으로 지르코니아 블록(Luxen Zirconia)를 사용하여, 교합면 두께는 0.3 mm, 0.5 mm, 1.5 mm, 축면 두께는 0.3 mm, 0.5 mm, 1.0 mm로 설정한 63개의 지르코니아 크라운을 제작하였다. 이 크라운은 니켈 크롬 다이에 레진 시멘트를 이용하여 접착하였다. 그 다음, electronic universal testing machine을 사용하여 크라운이 파절될 때까지 load-to fracture 시험을 진행하였다. 이후 scanning electron microscope (SEM)를 사용하여 크라운의 파절 형태를 관찰하였다. 통계 분석을 위해 Two-way ANOVA 방법을 사용하였고, 이에 대하여 Tuckey HSD test로 사후 검정을 시행하였다(P < .05). 결과: 모든 지르코니아 크라운의 평균 파절 저항 값은 구치부의 평균 저작력보다 큰 값을 나타냈다. 또한 Two-way ANOVA 결과, 지르코니아 크라운의 교합면 두께와 축면 두께는 파절 저항에 통계적으로 유의한 영향을 미치는 것으로 나타났다(P < .05). 그러나, 지르코니아의 축면 두께가 0.5 mm 이상일 때, 파절 저항에 미치는 영향은 통계적으로 유의한 차이를 보이지 않았다. 나타난 파괴 양상은 균열의 전파 양상에 따라 크라운의 부분 파절 또는 완전 파절로 나타났다. 결론: 이번 연구의 한계 내에서, 극도로 감소된 두께를 가진 CAD-CAM 단일구조 지르코니아 크라운은 구치부 교합력을 견딜 수 있는 적절한 파절 저항을 보였다. 또한, 지르코니아 크라운의 교합면 두께와 축면 두께는 파절 저항에 유의미한 영향을 나타냈으며 복합적인 결과를 보였다.

• Journal of Oral Medicine and Pain
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• 제30권2호
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• pp.247-255
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• 2005

본 연구의 목적은 교근에 보툴리눔 A형 독소주사량에 따른 교근위축 효과의 차이와, 교합안정장치의 동반치료시 교근위축의 증감의 관련성이 있는지, 부가적으로 주사부위로부터 어느정도 부위까지 근육위축의 효과가 나타날 수 있는지 전산화 단층촬영을 이용하여 평가하는데 있다. 자원자 32명을 8명씩 25 U, 25 U와 교합안정장치 장착, 35 U, 35 U와 교합안정장치 장착 군으로 나누어 보툴리눔 A형 독소주사량 차이와 교합안정장치 동반시의 교근위축효과 차이를 전산화 단층촬영을 이용하여 1, 2, 3 position의 3부위에서 측정, 평가한 결과 다음과 같은 결론을 얻었다. 1. 25 U 군에서 3 position 우측 두께감소, 25 U와 교합안정장치 군에서 3 position 우측 두께감소, 35 U 군에서 3 position 우측 두께감소와 좌측 면적감소를 제외하고 모든 부위에서 근육위축효과가 나타났으며 35 U와 교합안정장치 군에서는 모든 부위에서 근육위축효과가 유의성 있게 나타났다. (P < 0.05) 2. 보툴리눔 독소주사량 차이(25 U와 35 U)에 따른 근육 두께와 면적의 감소효과 차이는 나타나지 않았다. (P > 0.05) 3. 교합안정장치를 장착했을 때 근육두께 감소효과가 증가하는 것으로 나타났다. (P <0.05) 이상의 결과를 종합해 볼 때 교근비대 치료에 있어서, 보툴리눔 독소주사 이용시 교합안정장치의 동반치료가 보다 높은 근육위축 효과를 보이기에 이를 임상적으로 적용할 가치가 높다고 사료된다.

• 대한치과교정학회지
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• 제24권2호
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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.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.416-422
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• 2017

PURPOSE. To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns. MATERIALS AND METHODS. Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typodont mandibular first molar was prepared with less tooth reduction: 1 mm occlusal and proximal/axial wall reduction and 0.8 mm chamfer (Group B). Twenty crowns were milled from each preparation corresponding to control group (n=5) and conditioned group of simultaneous thermal and mechanical loading in aqueous environment (n=15). All crowns were then loaded until fracture to determine the fracture load. RESULTS. The mean (SD) fracture load values (in Newton) for Group A were 2340 (83) and 2149 (649), and for Group B, 1752 (134) and 1054 (249) without and with fatigue, respectively. Reducing tooth preparation thickness significantly decreased fracture load of the crowns at baseline and after fatigue application. After fatigue, the mean fracture load statistically significantly decreased (P<.001) in Group B; however, it was not affected (P>.05) in Group A. CONCLUSION. Reducing the amount of tooth preparation by 0.5 mm on the occlusal and proximal/axial wall with a 0.8 mm chamfer significantly reduced fracture load of the restoration. Tooth reduction required for lithium disilicate crowns is a crucial factor for a long-term successful application of this all-ceramic system.

• 구강회복응용과학지
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• 제35권2호
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• pp.90-97
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• 2019

목적: 교합접촉면적에 관련된 이전의 연구들은 교합두께 수준이나 교합측정방법 상 부정확성이 한계로 지적되어 왔다. 본 연구의 목적은 머리 위치가 교합접촉면적에 미치는 영향을 광조사교합분석법을 이용하여 조사하는 것이다. 연구 재료 및 방법: 건전한 치열을 갖는 54명(남성 44명, 여성 10명, 23 - 33세)을 대상으로 시험을 진행하였다. 머리 위치와 교합접촉면적의 관계를 알아보기 위해 시험대상은 치과용 유닛체어에 세 가지 자세(누운 자세($0^{\circ}$), 기울인 자세($45^{\circ}$), 직립 자세($90^{\circ}$))로 하여 최대 교두간 접촉위를 이용하여 악간관계기록을 채득하였다. 광조사교합분석기($BiteEye^{(R)}$)를 이용하여 교합접촉면적을 분석하였다. SPSS 25.0을 이용하여 유의수준 95%에서 통계분석을 시행하였다. 결과:머리 위치는 교합접촉면적과 유의미한 영향이 없는 것으로 나타났다(P > 0.05). 결론: 머리 위치는 교합접촉면적에 유의미한 영향이 없으므로 교합관계가 안정적이라면 최대 교두간접촉위의 악간관계 기록 채득 시 환자의 자세는 변수가 되지 않으며 광조사교합분석기를 이용한 교합접촉면적의 측정은 재료적, 용이성 측면으로 유용하다고 할 수 있다.

• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.388-395
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• 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.