• 구강회복응용과학지
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• 제39권4호
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• pp.222-228
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• 2023

교모는 치아 간의 접촉으로 인하여 치아 경조직이 소실되는 것으로, 심한 경우 상아질이 노출되어 선택적인 부식과 치아의 과도한 마모가 동반되는데, 이를 cupping이라고 부른다. 이러한 병소를 치료하지 않고 방치할 경우 병소의 크기가 점차 커지게 되어 지지되지 않는 법랑질이 파절되고, 결과적으로 심미성과 저작 기능이 저하된다. 본 증례보고에서는 심한 교모로 인해 cupping과 법랑질 파절이 동반된 환자에서 유기필러가 함유되어 부드러운 성질을 지닌 레진을 이용하여 직접수복을 실시하였다. 6년 후의 경과관찰에서 교합면의 충전은 대부분 탈락하였으나 협측의 충전은 비교적 온전하게 남아 있음을 관찰할 수 있었고, 이런 형태의 레진이 교합력이 크게 가해지는 부위보다는 교합력이 비교적 약하게 가해지는 부위에 적합한 재료임을 확인할 수 있었다.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.8-19
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• 2009

본 연구의 목적은 다양한 교합하중 조건하에서 아말감, 복합레진, 세라믹 인레이, 그리고 금 인레이로 수복한 근관치료된 상악 제2소구치의 음력분포를 3차원 유한요소법으로 분석하는 것이다. 발치된 상악 제2소구치를 이용하여 근관치료된 3차원 유한요소모형을 제작하였다. 제작된 소구치 모형의 근관와동을 위 4가지 재료로 각각 수복한 후, 협측교두 (Load-1) 또는 설측교두 (Load-2)에 500 N의 하중을, 설측교두와 근심변연에 총 170 N의 하중 (Load-3)을 가하였다. 세 가지의 하중조건 하에서 각 수복물에 따른 협측과 설측의 치경부 그리고 교합면의 정중구에서 나타나는 인장응력의 분포양상을 ANSYS 프로그램으로 분석하여 다음과 같은 결과를 얻었다. 1. 모든 수복물의 경우에서 Load-1에서는 설측의 치경부, Load-2에서는 협측의 치경부에서 높은 응력이 관찰되었고 수복물 종류에 따른 차이는 관찰되지 않았다. 2. 모든 수복물의 경우에서 교합면의 하중점 근처 와정중구를 따라 높은 응력이 관찰되었고 수복물 종류에 따라 약간의 차이가 관찰되었다. 3. 모든 수복물의 경우에서 Load-3에서는 하중점 근처에서 높은 응력이 관찰되었고 수복물 종류에 따른 차이는 관찰되지 않았다.

• 대한치과교정학회지
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• 제23권4호
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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.

• 대한치과기공학회지
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• 제46권2호
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• pp.36-41
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• 2024

Purpose: This study aimed to generate virtual mandibular left first molar teeth using deep convolutional generative adversarial networks (DCGANs) and analyze their matching accuracy with actual tooth morphology to propose a new paradigm for using medical data. Methods: Occlusal surface images of the mandibular left first molar scanned using a dental model scanner were analyzed using DCGANs. Overall, 100 training sets comprising 50 original and 50 background-removed images were created, thus generating 1,000 virtual teeth. These virtual teeth were classified based on the number of cusps and occlusal surface ratio, and subsequently, were analyzed for consistency by expert dental technicians over three rounds of examination. Statistical analysis was conducted using IBM SPSS Statistics ver. 23.0 (IBM), including intraclass correlation coefficient for intrarater reliability, one-way ANOVA, and Tukey's post-hoc analysis. Results: Virtual mandibular left first molars exhibited high consistency in the occlusal surface ratio but varied in other criteria. Moreover, consistency was the highest in the occlusal buccal lingual criteria at 91.9%, whereas discrepancies were observed most in the occusal buccal cusp criteria at 85.5%. Significant differences were observed among all groups (p<0.05). Conclusion: Based on the classification of the virtually generated left mandibular first molar according to several criteria, DCGANs can generate virtual data highly similar to real data. Thus, subsequent research in the dental field, including the development of improved neural network structures, is necessary.

• The Journal of Advanced Prosthodontics
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• 제11권3호
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• pp.162-168
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• 2019

PURPOSE. The aim of this study was to evaluate the effect of occlusal adjustments on the surface roughness of yttria-tetragonal zirconia polycrystal (Y-TZP) and wear of opposing artificial enamel. MATERIALS AND METHODS. Twenty-five Y-TZP slabs from each brand (Lava, 3M and Bruxzir, Glidewell Laboratories) with different surface conditions (Control polished - CPZ; Polished/ground - GRZ; Polished/ground/repolished - RPZ; Glazed - GZ; Porcelain-veneered - PVZ; n=5) were abraded (500,000 cycles, 80 N) against artificial enamel (6 mm diameter steatite). Y-TZP roughness (in ${\mu}m$) before and after chewing simulation (CS) and antagonist steatite volume loss (in $mm^3$) were evaluated using a contact surface profilometer. Y-TZP roughness was analyzed by three-way analysis of variance (ANOVA) and steatite wear by two-way ANOVA and Tukey Honest Difference (HSD) (P=.05). RESULTS. There was no effect of Y-TZP brand on surface roughness (P=.216) and steatite loss (P=.064). A significant interaction effect (P<.001) between surface condition and CS on Y-TZP roughness was observed. GZ specimens showed higher roughness after CS (before CS - $3.7{\pm}1.8{\mu}m$; after CS - $13.54{\pm}3.11{\mu}m$), with partial removal of the glaze layer. Indenters abraded against CPZ ($0.09{\pm}0.03mm^3$) were worn more than those abraded against PVZ ($0.02{\pm}0.01mm^3$) and GZ ($0.02{\pm}0.01mm^3$). Higher wear caused by direct abrasion against zirconia was confirmed by SEM. CONCLUSION. Polishing with an intraoral polishing system did not reduce the roughness of zirconia. Wear of the opposing artificial enamel was affected by the material on the surface rather than the finishing technique applied, indicating that polished zirconia is more deleterious to artificial enamel than are glazed and porcelain-veneered restorations.

• 대한치과의사협회지
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• 제50권1호
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• pp.22-30
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• 2012

The methods for the occlusal force measurement have long been developed. The occlusal analyzing equipment utilizing the pressure-sensitive film (Prescale) is useful for the assessment and comparison among large group of patients. On the other hand, the apparatus which uses the grid-based sensor sheet (T-scan) can be a useful assistant for acquiring the well-balanced occlusion. The device that can process the electrical input from the strain gauge which is attached to the tooth surface can collect the dynamic data of actual masticatory force. This device has been developed for the measurement of actual mastication with the food bolus and it can be a useful method for the comparison before and after the restorative treatment. Occlusal force measurement can be applied for the analysis of therapeutic action, diagnosis of crack- tooth syndrome, temporomandibul ar disease, and idiopathic implant loosening.

• 대한치과보철학회지
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• 제37권1호
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• pp.127-133
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• 1999

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the upper first premolar. After 10 metal dies were made fir each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (630N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength(378N). There were no significant differences of the fracture strength by axial inclination in same occlusal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.

• 대한치과보철학회지
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• 제39권3호
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• pp.313-318
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• 2001

Masticatory function is more important than esthetics in posterior fixed restoration. The usual technique-mounting the casts on a semi-adjustable articulator, etc. -cannot make all patients satisfied with their restorations. For example, functionally generated path technique can be an easier and more satisfactory method in the restoration of group function. These clinical reports describe various approaches for occlusal restoration of relatively simple posterior fixed protheses according to patients occlusal patterns. The 3-unit bridge restoration is one of the most popular treatment options in prosthodontics. Because dentists have much experiences of it, they restore a missing span of one tooth mechanically, that is, without special consideration. While esthetics is important in making an anterior 3-unit fixed prostheses, mastication is more focused on in posterior 3-unit bridge restoration. Many dentists are concerned about various aspects in esthetics, such as morphology of the tooth, value, chroma, hue, translucency, surface texture, etc. But they do not usually consider various methods to restore occlusion. They treat one-tooth-missing area in a similar way in spite of patients having variety of occlusal patterns. Three cases are presented here in 3 or 4-unit bridge restoration. They show some methods to restore patients' occlusal patterns.

• Journal of Oral Medicine and Pain
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• 제25권2호
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• pp.205-214
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• 2000

This study was performed to investigate the relationship between mandibular midline shift and anteroposterior first molar occlusal relation, and their effects on the mandibular height and the occlusal plane angle. For this study, 49 patients with temporomandibular disorders were selected. They did not show facial asymmetry and their facial midline coincide with maxillary dental midline. Upper and lower mandibular impression were taken and the casts were fabricated. Amount and direction of the mandibular midline shift and the anteroposterior shift between the two occluding first molars were measured on the casts. Several items related to height such as mandibular height from top of the articular surface of the condyle to curve changing point between antegonial notch and mandibular angle, condylar height which was the vertical distance from the articular surface to retroepicondyle of the condyle, and sigmoid height from the deepest point of sigmoid notch to the curve changing point and the occlusal plane angle were also measured on the panoramic and on the transcranial radiographs. Correlation between midline shift and anteroposterior first molar relation and comparison between right and left mandibular height by the midline shift and the first molar relation were analysed by SPSS windows program. The results of this study were as follows : 1. Mean amount of midline shift in the subjects with midline shift were 2.0mm for both side, respectively. The first molar relation of the ipsilateral side of midline shift showed Angle class II tendency and the contralateral side showed Angle class III tendency, which meant drift of the dentition to the side of the midline shift. 2. The occlusal plane angle on the panoramic radiograph were $13.0^{\circ}$ in right, and $12.5^{\circ}$ in left side, and their were no correlation between occlusal plane angle and mandibular midline shift and the first molar occlusal relation. 3. Angle's classification for both sides of the first molar relation were same in about half of all the subjects. Amount of deviation from class I first molar relation, however, were decreased in the contralateral side of observed side. 4. Mandibular height of the ipsilateral side to which mandibular midline shift showed tendency of lower than that of the contralateral side, and there was a tendency that the height was higher in class III subjects, then class II subjects, and lower in class I subjects. However, condylar height did not show any difference in the subjects with midline shift and also show no difference by the first molar occlusal relation.

• 대한치과보철학회지
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• 제60권4호
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• pp.320-329
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• 2022

생리적 마모는 일생 동안 불가피하게 일어나고 정상현상이라고 볼 수 있다. 하지만, 병적인 마모는 교합면에 치명적 손상을 야기하고 심미 및 적절한 전방유도를 파괴 할 수 있다. 따라서 교합면 마모 회복을 위해서는 철저한 평가와 진단이 필요하다. 본 증례의 환자는 하악 치아 순면과 상악 치아 설면의 심한 마모를 보였다. 수직교합고경을 분석 하였고, 부족한 보철수복공간을 회복을 위해 수직교합고경을 높여서 치료하기로 하였다. 수직교합고경이 결정 된 후에는 보통 진단 왁스업을 하여 치료를 진행한다. 본 증례는 심한 마모로 인한 교합붕괴 및 수직교합고경이 상실된 환자에서, 기존의 진단왁스업 과정을 다양한 디지털 도구를 사용하는 방법으로 대체하였다. 진단왁스업은 소프트웨어에서 디자인되어 디지털로 임시보철물을 제작하였다. 임시보철물 검증을 통해, 수직교합고경 및 적절한 전방유도로 회복되었다.