Abstract: Objective To compare the effects of two ceramic veneer bonding methods on gingival health, the gingival retraction trauma and the mechanical gingival epithelium trauma, and to provide reference for clinical application. Methods Thirty-six symmetrical teeth after veneer preparation of 11 patients who were periodontally healthy were selected in this homologous pairing design. Teeth in one side were randomly chosen to be treated with retraction cord in cementing procedure and the other side with polishing bonding. The healthy adjacent teeth were chosen as the control group. After one week and two weeks after bonding, restoration teeth had a return visit. Plaque index (PLI), probing depth (PD) ,and Mazza index (MI)of the restoration teeth were measured after cementation, as well as the adjacent natural teeth. Differences in clinical parameters were analyzed with the Friedman signed ranks test and Wilcoxon signed ranks test (α=0.05). One year later, the pigmentation in margin of cementation and visual gingival recession were observed. Results The periodontal parameters were not statistically significant among the groups at two intervals except for the Mazza index(P=0.004), which increased in two groups after 1 week while there was no statistical significance(P=0.16) between cord group(1.00(0.75~1.00) )and the cordless group.( 1.00(1.00~2.00)). No obvious pigmentation in margin of the cementation and visual gingival recession was observed after one year. Conclusions Both the two techniques injure the gingival health by causing a temporary gingival inflammation which is indicated by Mazza index (MD)and can not be traced after 2 weeks. No statistical significance between the two techniques on gingival health can be measured in a short period.

Key words: Retraction Cord Gingival Trauma Ceramic Veneer Cementation