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치의학박사학위논문 상아질접착제의세포독성 평가방법에관한연구 년 월 서울대학교대학원 치의과학과치과생체재료과학전공 김경환
상아질접착제의세포독성 평가방법에관한연구 지도교수양형철 이논문을치의학박사학위논문으로제출함 년 월 서울대학교대학원 치의과학과치과생체재료과학전공 김경환 김경환의박사학위논문을인준함 년 월 위원장 부위원장 인 인 위원 인 위원 인 위원 인
요약 국문초록
주요어 상아질접착제 세포독성 수복용레진 산소저해층 표면경도 학번
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Test conditions Application of DBA 1 Location of DBA in the curing step RRC 2 curing step A: Glass disk Onto glass disc On glass disc B: Similar to clinical condition Onto PP 3 film On PP film (before attachment to an RRC disc) After attachment of DAB to RRC disc (DAB located between PP film and RRC disc at the RRC curing step) C: Affected by polymerization of RRC, sufficient oxygen environment Onto uncured RRC disc On uncured RRC disc (in open-air environment) After curing of DAB on RRC disc D: Affected by polymerization of RRC, limited oxygen environment Onto PP film Between PP film and uncured RRC disc (after attachment to uncured RRC disc) After curing of DAB (DAB located between PP film and RRC disc at the RRC curing step) E: Unaffected by polymerization of RRC, limited oxygen environment Onto PP film Between PP film and pre-cured RRC disc (after attachment to pre-cured RRC disc) Before attachment of DAB to RRC disc - 11 -
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type of grade cell/response 0 1 2 3 4 0 rare, 1-5 5-10 sever infiltration packed 0 rare, 1-5 5-10 sever infiltration packed 0 rare, 1-5 5-10 sever infiltration packed 0 rare, 1-5 5-10 sever infiltration packed 0 rare, 1-2 3-5 sever infiltration packed 0 minimal mild moderate severe - 13 -
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Abstract A study on the cytotoxicity evaluation method of dentin bonding agents Kyunghwan Kim, D.D.S., M.S. Dept. of Dental Biomaterials Science Graduate School, Seoul National University 1. Purpose Dentin bonding agents are being used for bonding composite resins to dentin and minimize microleakage which can destruct the adhesion. Because unpolymerized resin monomers in dentin bonding agents can affect dental pulp cells via dentinal tubules, polymerization of bonding agents are important in the view point of biocompatibility. A variety of previous studies has reported that high cytotoxicity of dentin bonding agents although the agents are being used widely in dental clinics. This suggests that the current cytotoxicity evaluation method overestimates the cytotoxicity of dentin bonding agents. In the process of teeth restoration, the bonding agents are being employed in adjacent to composite resins that are expected to affect the polymerization of bonding agents. We hypothesized the composite resins reduced the cytotoxicity of bonding agents by promote resin polymerization. The purpose of this study is to develop a cytotoxicity evaluation method of dentin bonding agents which consider the existence of restorative resin - 51 -
composites and oxygen inhibition layer. 2. Material and methods. Dentin bonding agents of fourth to seventh generation were used as follows; Adper Scotchbond Multipurpose Plus (3M ESPE, St Paul, MN, USA), Adper Single Bond 2 (3M ESPE, St Paul, MN, USA), Prime & Bond NT (Dentsply De Trey, Konstanz, Germany), Clearfil SE Bond (Kuraray Medical Inc. Osaka, Japan), One-Up Bond F Plus (Tokuyama Corporation, Tokyo, Japan) and ibond (Heraeus Kulzer, Hanau, Germany). Ceram X (Dentsply) was used as a restorative resin composite. The cytotoxicity of the dentin bonding agents were evaluated by serial dilution and agar overlay methods. For the cytotoxicity test, L929 mice fibroblasts (ATCC, Rockville, MD, USA) were used according to ISO10993-5 (Tests for cytotoxicity, in vitro method). In serial dilution test, bonding agents were polymerized on glass discs and extracted with cell culture media. In agar overlay assay, dentin bonding agents were polymerized on cured or uncured resin composite, and the effects of resin composites and oxygen inhibition layer on cytotoxicity were observed. To investigate the effects of restorative resin composites on the polymerization of bonding agents, Vickers hardness of bonding agents was measured on pre-cured or post-cured resin composite discs. Furthermore, mice implantation test performed to observe initial inflammatory reactions. - 52 -
3. Results In serial dilution test, cell viability was completely abolished by treatment with the undiluted extracts of all the bonding agents regardless of evaporation. After evaporation and light-curing, the ranking of cytotoxicity based on LC 50 was Scotchbond > Clearfil SE Bond > One-Up Bond > Prime&Bond NT > Single Bond 2 > ibond. In agar overlay test, Scotchbond was the most toxic bonding agent, and ibond was the least toxic in all conditions. In the agar overlay tests that mimic clinical situations, cytotoxicity of each dentin bonding agents were severely attenuated. The degree of effects of restorative resin composites and oxygen inhibition layers were various in different bonding agents. Vickers hardness number of all the bonding agents on post-cured resin composites increased significantly compared to values obtained with the pre-cured resin composites. This result suggests that the polymerization of composite resins strengthened the surface hardness of the attached bonding agents through the augmentation of resinous polymerization. Initial inflammatory reactions appeared in sub-epithelial implantation test, but the difference between the tests and negative control groups were not significant. Those results suggest that cytotoxicity of dentin bonding agents were overestimated by the conventional evaluation method. Furthermore, our new evaluation method mimicking clinical situation is expected to evaluate an acting cytotoxicity of dentin bonding agents. keywords : Dentin bonding agent, cytotoxicity, composite resin, oxygen inhibition layer, surface hardness Student Number : 2010-31212 - 53 -