Abstract: Objective To investigate the influence of surface roughness of tooth preparation on adhesive strength of different dental cements; in turn provide some reference and recommendation on the selection of dental rotary instruments and dental cements. Methods 60 dentin samples were prepared and randomly divided into 3 groups. 3 groups of samples were grinded by diamond burs with different grit-sizes (125μm、60μm、28μm). 2 samples were randomly selected from each group and were observed under SEM for the surface microprofile. The rest 18 samples from each group were evenly divided into 3 subgroups. Each subgroup was teamed with one of 3 dental cements: zinc polycarboxylate cement (ZP), glass ionomer cement (GI) and resin-modified glass ionomer cement (RMGI). Co-Cr alloy casts were cemented onto the dentin samples, and the adhesive strength was tested. Meanwhile, the type of failure was recorded for each sample. Statistical analysis was conducted with SPSS16.0 software. Results Both the surface roughness of tooth preparation and the type of dental cement have statistically significant influence on the adhesive strength. However, the interaction of the two factors was not significant. Samples grinded by 125μm-grit diamond burs had the highest adhesive strength, while the ones grinded by 28μm-grid diamond burs showed the lowest. Furthermore, RMGI exhibited the higher adhesive strength compared to ZP and GI. And there was no significant difference between ZP subgroup and GI subgroup. Conclusion Adhesive strength decreases in positive relation to surface roughness of tooth preparation. The rank of cements on adhesive efficiency is: RMGI>GI≈ZP. There is no obvious compatibility revealed between particular surface roughness and dental cements.

Key words: surface roughness, tooth preparation, cements, adhesive strength, rotary instruments