• 대한소아치과학회지
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• 제48권3호
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• pp.280-290
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• 2021

치수복조제는 치관부에 위치하기 때문에 색 안정성이 최종적인 심미성에 영향을 미치는 중요한 요소로 간주된다. 이 연구는 시간에 따른 치관의 색조 변화를 분석하여 치수복조제의 색조 안정성을 비교해보고자 하였다. 발거된 소구치의 치관에 와동을 형성하고 4가지 종류의 치수복조제를 충전하였다. 색상 변화는 분광광도계를 사용하여 재료를 넣기 전, 재료를 넣은 즉시, 재료를 넣고 1일 후, 1주 후, 2주 후, 4주 후, 8주 후, 12주 후, 16주 후에 측정을 시행하였다. Proroot white MTA^®와 TheraCal LC^®는 시간이 지남에 따라 지속적인 L^* 값의 감소와 ∆E^* 값의 증가를 보였다. 반면 Biodentine^®과 Well-root^TM PT는 유의한 L^* 값의 변화가 없었고 일정한 ∆E^* 값을 유지하였다. 방사선 불투과성 물질로 산화 비스무트가 포함된 치수복조제의 적용 시 치아의 색조 변화가 나타날 수 있으며, 법랑질의 두께가 얇은 유치의 수복이나 전치부의 심미 수복 시 치수복조제의 장기적인 색 안정성을 고려해야 한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.152-157
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• 2003

A typical die-set for enclosed-die forging of half axle gears in double action hydraulic press is presented, the important factors those influence on precision forming of half axle gears are analyzed, warm forming process of half axle gears is simulated by FEM software $DEFORM\_3D$. The results show, that proper die structure and dimension, suitable web thickness and position can improve material filling, ensure full filling of tooth cavity.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.594-594
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• 2001

Increased demand for esthetic restorations has promoted a growing interest in tooth-colored restorations even in the posterior regions. Preparation for specific types of indirect inlay and onlays may vary because of differences in fabrication steps for each commercial system and variations in the physical properties of the restorative materials. Preparations for indirect inlay/onlay basically are meant to provide adequate thickness for restorative material and at the same time a passive insertion pattern with rounded internal angles and well defined margins after deciding what type of restoration is indicated.(omitted)

• 대한치과의사협회지
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• 제51권1호
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• pp.12-17
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• 2013

Curing methods for denial resin-based materials are limited because of the need to polymerize quickly in the oral cavity at an ambient temperature. At present, most dental restorative composites use a camphorquinone-amine complex initiation, visible light-cure, one-component systems. Clinically, it is important to try to optimize the degree of conversion of res in composites using proper manipulation and adequate light-curing techniques to ensure the best outcome.

• The Journal of Advanced Prosthodontics
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• 제3권4호
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• pp.229-235
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• 2011

PURPOSE. The aim of this retrospective study was to evaluate cumulative survival rate (CSR) of Implantium implants followed for 5 years and association between risk factors and the CSR. MATERIALS AND METHODS. A total of two hundred forty-nine Implantium Implants System (Dentium, Seoul, Korea) placed in ninety-five patients from 2004 to 2009 were investigated with several identified risk factors (sex, systemic disease, smoking, alchohol, reason of tooth loss, length, arch (maxilla or mandible), replace tooth type (incisor, canine, premolar or molar) Kennedy classification, prosthodontic type, prosthodontic design, opposite dentition, abutment type, occlusal material, occlusal unit, splint to tooth, cantilever, other surgery). Clinical examination (mobility, percussion, screw loosening, discomfort, etc.) and radiographic examination data were collected from patient records including all problems during follow-up period according to protocols described earlier. Life table analysis was undertaken to examine the CSR. Cox regression method was conducted to assess the association between potential risk factors and overall CSR. RESULTS. Five of 249 implants were failed. Four of these were lost before loading. The 5-year implant cumulative survival rate was 97.37%. Cox regression analysis demonstrated a significant predictive association between overall CSR and systemic disease, smoking, reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The screw related complication was rare. Two abutment screw fractures were found. Another complications of prosthetic components were porcelain fracture, resin facing fracture and denture fracture (n=19). CONCLUSION. The 5-year CSR of Implantium implants was 97.37 %. Implant survival may be dependent upon systemic disease, smoking reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The presence of systemic diseases and combination of other surgical procedures may be associated with increased implant failure.

• 대한치과보철학회지
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• 제48권2호
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• pp.94-100
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• 2010

연구목적: 본 연구는 상악과 하악의 각 치아부위에 $Lava^{TM}$ All-Ceramic System을 이용하여 지르코니아 전부도재관을 제작하고 각각의 파절강도를 알아보고자 하였다. 연구방법:중절치와 견치는 절단연의 삭제량을 2.0 mm, 소구치와 대구치는 교합면의 삭제량을 1.5 mm, 그리고 축면 경사도는 $8^{\circ}$로하여모두8군의 실험군을 설정하였다. 금속 다이와 지르코니아 도재관을 제작한 후 레진시멘트 (Rely $X^{TM}$ Unicem)를 이용하여 합착하고 만능시험기상에서 치아 장축에 $30^{\circ}$경사지게 하여 중절치와 견치에 제작된 지르코니아 도재관은 절단연 중앙 부위에 하중을 가하였고, 소구치와 대구치에 제작된 지르코니아 도재관은 기능교두의 협설측 경사면 중앙부위에 하중이 가해지도록 한 후 파절강도를 측정하였다. 결과:1. 지르코니아 도재관의 평균 파절강도는 하악 제1대구치에서 2963 N으로 가장 높게 나타났으며, 하악 중절치에서 1035 N으로 가장 낮게 나타났다. 2. 지르코니아 도재관과 IPS Empress 도재관과의 평균 파절강도는 모든 치아에서 지르코니아 도재관이 더 크게 나타났다. 3. 지르코니아 도재관의 파절 양상은 하중이 가해진 중앙 부위에서 치아 장축으로 수직적인 파절상을 보였다. 4. 상악과 하악의 동일 부위에 제작된 지르코니아 도재관의 파절강도는 소구치에서 상악이 하악에 비하여 낮은 것으로 나타났으며 (P< .05), 다른 부위에서는 유의한 차이가 없었다 (P> .05). 결론: 본 실험의 결과로 지르코니아 도재관은 임상에서 활용하기에 만족할 만한 강도를 갖고 있음을 알 수 있었다.

• Restorative Dentistry and Endodontics
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• 제39권2호
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• pp.137-142
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• 2014

This article presents the successful surgical management of a failed mineral trioxide aggregate (MTA) orthograde obturation of a tooth with a history of impact trauma and perforated internal root resorption. A symptomatic maxillary lateral incisor with a history of perforation due to internal root resorption and nonsurgical repair using MTA was referred. Unintentional overfill of the defect with MTA had occurred 4 yr before the initial visit. The excess MTA had since disappeared, and a radiolucent lesion adjacent to the perforation site was evident radiographically. Surgical endodontic retreatment was performed using calcium enriched mixture (CEM) cement as a repair material. Histological examination of the lesion revealed granulation tissue with chronic inflammation, and small fragments of MTA encapsulated within fibroconnective tissue. At the one and two year follow up exams, all signs and symptoms of disease had resolved and the tooth was functional. Complete radiographic healing of the lesion was observed two years after the initial visit. This case report illustrates how the selection of an appropriate approach to treatment of a perforation can affect the long term prognosis of a tooth. In addition, extrusion of MTA into a periradicular lesion should be avoided.

• 대한치과의사협회지
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• 제55권2호
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• pp.128-138
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• 2017

Objective: The aim is to evaluate the potential of the mesiodens through the comparative inorganic analysis of 3rd molar teeth prior to clinical study. Material and methods: The extracted mesiodens and the 3rd molar teeth were prepared. The teeth are prepared as in the process of the autogenous tooth bone graft. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis was performed for inorganic analysis. Results: Rough and porous surfaces were observed in all materials in SEM analysis. Ca/P ratio of mesiodens was 1.55 and the 3rd molar was 1.22 in EDS analysis. XRD analysis shows that the 3 main peaks position were similar. This means that the graft materials are very similar to that of the crystallinity. Conclusions: The mesiodens and the 3rd molar teeth are very similar to the inorganic component. These results provide the reasonable rationale that mesiodens can be used as autogenous tooth bone graft in a clinic.

• 한국정밀공학회지
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• 제3권3호
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• pp.40-71
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• 1986

By developing a computer program for the systematic design of worm gears, the design formulae and tables of AGMA, JGMA, BS and DIN are analized and compared. The computer program can be used on micro-computers. According to the input data of the reduction ratio, the center distance. the driving torque and the material as design parameters, the program calculate the most efficient worm gear dimension. The variation of the design parameters and other empirical coefficients in case of resulting an inadequate design gear dimension can be easily modified throuth the way of interactive method between the user and the monitoring system of computer. A proposal of the standardization of worm gears was made in which a standard module according to the DIN 323 standard series number was applied. For the more exact and effective calculation of the stress concentration and the deformation of gear teeth, a computer program using the boundary element method is also developed. Even the strength of the special gear shape such as Niemann's "Cavex" gear can be calculated in a short CPU-time. The most effort of this study has been layed on the developing a computer program for the correction of a tooth profile and face width which is most important design factor for an exact and wide teeth contacts under loads, especially by great and wide gears. For this purpose were investigated the tooth stiffness, the mesh interferences and the kinematics and the dynamics of gear mesh. The deflection and the deformation of the gear shaft due to the loads acting on gear and shaft were aslo considered. Some examples have shown the sufficient good status of teeth contact in which the correction of the tooth profile and face width were accomplished due to the calculated results.d results.

• 대한소아치과학회지
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• 제24권3호
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• pp.678-687
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• 1997

Cystic lesions of the mandible are fairly common and usually a presumptive diagnosis is made readily, more often on the basis of roentgenographic appearance than by any other means. Occasionally, however, it is easy to fall into errors of diagnosis which may affect one's choice of treatment. The diagnosis in these situations are usually resolved by the histopathologic examination of material obtained by surgical exploration. The present discussion to the lesions which can be most easily confused in the roentgenographic interpretation, that is, the traumatic bone cyst, the dentigerous cyst, the radicular cyst. These lesions often grow to considerable size before they cause any subjective or objective symptoms. Less frequently, perhaps, the patient presents himself with the complaint of enlargement of the affected part, a discharge, or pain. On rare occasions the first sign is fracture through the cyst cavity. In any case, an adequate roentgenographic survey by means of extraoral films is essential. This is the primary means of diagnosis. The three lesions in mandible, reported here, resembled each other roentgenographically in that they were osteolytic lesions. The follicular and radicular cysts usually have a smooth periphery and may be surrounded by a white line. The follicular cyst, slow-growing lesions, is usually associated with an unerupted tooth. The radicular cyst, the most common type of the odontogenic cyst, is always associated with a nonvital tooth, or it may persist as a "residual" radicular cyst after the causative tooth has been extracted. The traumatic bone cyst can often be differentiated from the first two in that the periphery is less definite and is irregular. It is thought that because it does not occur in older people, the lesion is self-limiting and heals spontaneously if left alone.