The application of a resin impregnation technique to dentin using a vacuum

Background: There is a technique in the industry called resin procedures like resin coating. For example, epoxy resin is injected to repair cracks in concrete of 0.2 mm or larger. In addition, a casting product can be strengthened when resin is injected to fill in a blowhole. A vacuum can be utilized to allow the resin to penetrate into every corner. In this study, we investigate whether bonding resin can deeply penetrate with the use of a vacuum. Methods: Six non-carious extracted human first premolars were used. For bonding resin into dentin, one-step adhesive was used. The root of each tooth was cut at the cement and soaked in bonding resin. Immersion was performed under the conditions of atmospheric pressure and vacuum (-70 kPa). The fluorescent dye Rh concentration of 0.1% for confirming resin penetration. Each tooth underwent about 200 polishing and was placed on glass slides. Images of the completed specimens were obtained by fluorescent microscopy. Results: The dyed resin that penetrated into the dentin tubules under vacuum formed a long and dense resin tag. On the other hand, the dyed resin that penetrated into the dentin tubules under atmospheric pressure formed a sparse and unformed resin tag. Conclusion: This study suggests that a vacuum is effective for deep penetration of bonding resin.