Cytotoxic effect of silorane and methacrylate based composites on the human dental pulp stem cells and fibroblasts.

OBJECTIVES: The aim of this study was to compare the cytotoxic effect of a methacrylate-based and a silorane-based composite on the human dental pulp stem cells (DPSCs) versus human dental pulp fibroblasts (DPFs). STUDY DESIGN: Samples of the Filtek Z250 and P90 were polymerized and immersed in the culture medium to obtain extracts after incubation for one, seven and 14 days. Magnetic cell sorting based on the CD146 expression was performed to purify DPSCs and DPFs. After incubation of both cells with the extracts, cytotoxicity was determined using the MTT test. RESULTS: For the extracts of first and seventh day, both composites showed significantly lower cytotoxicity on DPSCs than DPFs (p=0.003). In addition, there was a significant difference in the time-group interaction of both materials indicating different cytotoxic behaviours (p=0.014). In contrast to Z250, exposure to the 14th day extract of P90 resulted in higher cell viability compared to that of day seven. CONCLUSIONS: DPSCs are less susceptible to the cytotoxic effect of the composites than DPFs. Compared to Z250, the cytotoxic effect of silorane-based composite decreases as the time passes on. This difference should be considered, particularly in deep cavities, in order to preserve the regenerative capacity of the pulp.

Microleakage of nanofilled resin-modified glass-ionomer/silorane- or methacrylate-based composite sandwich Class II restoration: effect of simultaneous bonding.

OBJECTIVES: Microleakage of composite restorations at the cervical margin placed apically to the cementoenamel junction (CEJ) is still a concern. This study evaluated the effect of simultaneous bonding application on cervical sealing of nano-ionomer/silorane- or methacrylate-based composite open sandwich Class II restorations in the modified technique compared with that of conventional bonding. METHODS AND MATERIALS: In 60 sound maxillary premolars, two standardized Class II cavities were prepared with cervical margins 1 mm below the CEJ. The teeth were randomly divided into six groups of 10 teeth each. In the first three groups (groups 1-3), Clearfil SE Bond and Clearfil APX (Kuraray) were used for restoration in the total bonding technique (group 1), conventional open sandwich technique associated with a nano-ionomer (Ketac N100, 3M ESPE) (group 2), and modified open sandwich technique with simultaneous bonding application for both nano-ionomer and composite (group 3). In the second three groups (groups 4-6), Silorane Adhesive and Filtek Silorane composite (3M ESPE) were used in the same manner as in the first three groups, respectively. RESULTS: The simultaneous bonding application in the modified sandwich restorations (with SE Bond or Silorane Adhesive) resulted in a significant reduction of the cervical microleakage compared with that of the conventional bonding (p<0.05). However, microleakage of the modified technique was similar to that of the total bonding (with SE Bond or Silorane Adhesive) (p>0.05), both showing good marginal seal.

Biofilm formation on composite resins for dental restorations: an in situ study on the effect of chlorhexidine mouthrinses.

PURPOSE: Biofilm formation on the surface of dental restorative materials by oral bacteria is considered an important step in the development of secondary caries. The aim of this study was to evaluate the in situ effect of a chlorhexidine (CHX)-containing mouthrinse on the biofilm formation occurring on the surface of human enamel and of two resin-based commercially available materials: a silorane-based material (Filtek Silorane®) and a methacrylate-based material (Filtek Supreme XT®). METHODS: 53 disks were obtained for each of the two composites and 37 disks for enamel. The surface was characterized by determining the surface roughness and the surface free energy of 5 samples for each of the three materials tested, then the remaining samples were mounted on splints worn by 16 volunteers. The participants were randomly divided into two groups: an experimental group that used 0.12% CHX-based mouthrinse and a control group that used a placebo mouthrinse. Biofilm formation on the different surfaces after a 24 h period was assessed using MTT assay. RESULTS: The two composites in the group treated with the placebo mouthrinse showed a similar biofilm formation, which was significantly higher than that occurring on enamel surfaces. The CHX-based mouthrinse significantly reduced biofilm formation on the surfaces of the two resin-based materials when compared with the placebo mouthrinse. The reduction was particularly relevant on the Filtek Silorane surfaces. CONCLUSIONS: The new silorane-based material seems to interact with CHX in a promising way from the point of view of biofilm formation control.