IADR Abstract Archives
Exposure of dental pulp to monomers: an in-vitro model.
Objectives: To evaluate the toxicity of dental adhesives, accurate quantification of composite ingredients that may diffuse through the dentinal tubules is important. The aim of this study was to assess the diffusion of residual monomers from dental adhesive systems through dentin disks using an in-vitro pulp chamber model.
Methods: Dentin disks with a thickness of 0.3 mm were produced from human third molars. After etching the pulpal side of the disk with citric acid (50%), the disks were fixed between two open-ended glass tubes, representing an in-vitro pulp chamber. The etch-and-rinse adhesive OptiBond FL (Kerr) and the self-etch adhesive Clearfil SE Bond (Kuraray) were applied as per manufacturer’s instructions to the dentin side of the disks (lower part of model), after which a flowable composite Tetric Evoflow (Ivoclar Vivadent) was applied, while in the pulpal part (upper part), the glass tube was filled with 600 µL water. The transdentinal diffusion of different monomers after 24h was quantified using ultra-performance liquid chromatography tandem mass spectrometry. As control, no adhesive was applied. To evaluate the worst-case situation, the diffusion was additionally tested when the adhesive was applied without polymerization.
Results: The monomers HEMA, CQ, BisGMA, GPDM, 10-MDP and UDMA were found to be able to diffuse through the dentin disks. Monomers with a lower molecular weight proved to be more prone for diffusion compared to monomers with a higher molecular weight. As expected, absence of curing resulted in significantly higher monomer diffusion compared to the cured conditions.
Conclusions: All monomers can diffuse through dentin, but the quantity depended on the molecular weight. However, when the adhesive is polymerized and composite is applied, only minute amounts of monomers were able to diffuse. This in-vitro research contributes to a more detailed understanding about the exposure of dental pulp to monomers from dental adhesives.
Methods: Dentin disks with a thickness of 0.3 mm were produced from human third molars. After etching the pulpal side of the disk with citric acid (50%), the disks were fixed between two open-ended glass tubes, representing an in-vitro pulp chamber. The etch-and-rinse adhesive OptiBond FL (Kerr) and the self-etch adhesive Clearfil SE Bond (Kuraray) were applied as per manufacturer’s instructions to the dentin side of the disks (lower part of model), after which a flowable composite Tetric Evoflow (Ivoclar Vivadent) was applied, while in the pulpal part (upper part), the glass tube was filled with 600 µL water. The transdentinal diffusion of different monomers after 24h was quantified using ultra-performance liquid chromatography tandem mass spectrometry. As control, no adhesive was applied. To evaluate the worst-case situation, the diffusion was additionally tested when the adhesive was applied without polymerization.
Results: The monomers HEMA, CQ, BisGMA, GPDM, 10-MDP and UDMA were found to be able to diffuse through the dentin disks. Monomers with a lower molecular weight proved to be more prone for diffusion compared to monomers with a higher molecular weight. As expected, absence of curing resulted in significantly higher monomer diffusion compared to the cured conditions.
Conclusions: All monomers can diffuse through dentin, but the quantity depended on the molecular weight. However, when the adhesive is polymerized and composite is applied, only minute amounts of monomers were able to diffuse. This in-vitro research contributes to a more detailed understanding about the exposure of dental pulp to monomers from dental adhesives.