Effect of different smear layers on the bonding performance and durability of four adhesive systems / 中国组织工程研究

ABSTRACT

BACKGROUND: When the tooth surface is treated with a rotary or manual instrument, a smudge layer is formed on the enamel and dentin by debris generated by cutting and abrasion. The bonding interface between the adhesive and the dentin is considered as a weak part in the direct repair process. To clarify the effect of smear layer on different kinds of adhesive is significantly important for dentists to select and correctly use the adhesive in clinical treatment. OBJECTIVE: To evaluate the effect of different diamond burs on the dentin bonding performance of four adhesive systems to dentin after 24 hours and 100 days of artificial saliva-storage. METHODS: Adhesive systems were (1) VSA (Optibond Versa, Kerr); (2) AIO (Optibond All in One, Kerr); (3) SBU (Single bond Universal, 3M); (4) GLU (Bond 5, Gluma, Heraeus). In present study, 80 extracted human molars were randomly divided into four groups and each group is divided into 4 subgroups. Dentin surfaces were prepared by (1) 600-grit SiC-paper (control group); (2) super-fine diamond bur; (3) regular diamond bur; (4) coarse diamond bur. Bonding agent was applied according to each manufacturer’s instruction. After light-curing, dentin surfaces were built-up with resin composite (A2, CHARISMA, Heraeus). The micro-tensile bond strength was determined after 24 hours and 100 days of storage in artificial saliva at 37 °C. The fractured surfaces on dentin side were observed by scanning electron microscope. RESULTS AND CONCLUSION: (1) Storage for 24 hours There was no significant difference among groups under VSA and GLU. Under SBU and AIO, the bond strength in the coarse diamond bur group was significantly lower than that in the control group (P 0. 05). Using coarse diamond bur, the bond strength in the VSA group had significant difference compared with the AIO, GLU and SBU groups (P 0. 05). (2) Storage for 100 days, there was no significant difference among groups under VSA and GLU. Under SBU, the bond strength in the coarse diamond bur group was significantly lower than that in the control group (P 0. 05). Using regular diamond bur, the bond strength showed no significant difference in the GLU group compared with the SBU, and VSA groups (P > 0. 05). Using coarse diamond bur, the bond strength had no significant difference between VSA and AIO groups (P < 0. 05). (3) Using VSA, the bond strength in each group at 100 days showed significant difference compared with that at 24 hours (P < 0. 05). (4)Compared with immersed for 24 hours, the ratio of bond interface and combined crack in the VSA, SBU and GLU groups after immersed for 100 days was increased, especially the VSA group. Compared with the other groups, the ratio of bond interface and combined crack in the GLU group after immersed for 24 hours and 100 days both increased by 50%. (5) These results indicate that preparation by different burs produces different smear layers, which has significant effect to self-etching adhesive system and has no significant effect to total-etching adhesive system. Storage time makes effect on different adhesives.