Jorge Janaina Habib, Giampaolo Eunice Teresinha, Vergani Carlos Eduardo, Machado Ana Lúcia, Pavarina Ana Cláudia, Carlos Iracilda Zeppone
Department of Dental Materials and Prosthodontics, Araraquara Dental School, Araraquara, São Paulo, Brazil.
J Appl Oral Sci. 2006 Jun;14(3):203-7. doi: 10.1590/s1678-77572006000300011.
Most denture base acrylic resins have polymethylmethacrylate in their composition. Several authors have discussed the polymerization process involved in converting monomer into polymer because adequate polymerization is a crucial factor in optimizing the physical properties and biocompatibility of denture base acrylic resins. To ensure the safety of these materials, in vitro cytotoxicity assays have been developed as preliminary screening tests to evaluate material biocompatibility. (3)H-thymidine incorporation test, which measures the number of cells synthesizing DNA, is one of the biological assays suggested for cytotoxicity testing.
The purpose of this study was to investigate, using (3)H-thymidine incorporation test, the effect of microwave and water-bath post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins.
Nine disc-shaped specimens (10 x 1 mm) of each denture base resin (Lucitone 550 and QC 20) were prepared according to the manufacturers' recommendations and stored in distilled water at 37 degrees C for 48 h. The specimens were assigned to 3 groups: 1) post-polymerization in a microwave oven for 3 min at 500 W; 2) post-polymerization in water-bath at 55 degrees C for 60 min; and 3) without post-polymerization. For preparation of eluates, 3 discs were placed into a sterile glass vial with 9 mL of Eagle's medium and incubated at 37 degrees C for 24 h. The cytotoxic effect of the eluates was evaluated by (3)H-thymidine incorporation.
The results showed that the components leached from the resins were cytotoxic to L929 cells, except for the specimens heat treated in water bath (p<0.05). Compared to the group with no heat treatment, water-bath decreased the cytotoxicity of the denture base acrylic resins.
The in vitro cytotoxicity of the tested denture base materials was not influenced by microwave post-polymerization heat treatment.
大多数义齿基托丙烯酸树脂的成分中含有聚甲基丙烯酸甲酯。几位作者已经讨论了将单体转化为聚合物的聚合过程，因为充分聚合是优化义齿基托丙烯酸树脂物理性能和生物相容性的关键因素。为确保这些材料的安全性，已经开发了体外细胞毒性试验作为评估材料生物相容性的初步筛选试验。（3）H-胸腺嘧啶核苷掺入试验，用于测量合成DNA的细胞数量，是建议用于细胞毒性测试的生物学试验之一。
本研究的目的是使用（3）H-胸腺嘧啶核苷掺入试验，研究微波和水浴后聚合热处理对两种义齿基托丙烯酸树脂细胞毒性的影响。
按照制造商的建议制备每种义齿基托树脂（Lucitone 550和QC 20）的九个圆盘形标本（10×1毫米），并在37℃的蒸馏水中储存48小时。将标本分为3组：1）在微波炉中以500W功率后聚合3分钟；2）在55℃水浴中后聚合60分钟；3）不进行后聚合。为了制备洗脱液，将3个圆盘放入含有9mL伊格尔培养基的无菌玻璃瓶中，并在37℃下孵育24小时。通过（3）H-胸腺嘧啶核苷掺入评估洗脱液的细胞毒性作用。
结果表明，从树脂中浸出的成分对L929细胞具有细胞毒性，但水浴热处理的标本除外（p<0.05）。与未热处理组相比，水浴降低了义齿基托丙烯酸树脂的细胞毒性。
测试的义齿基托材料的体外细胞毒性不受微波后聚合热处理的影响。
