RESUMO
Objective: To evaluate the effects of 4 gingival retraction methods. Methods: 48 premolars were selected from 12 periodontal healthy volunteers and were randomly divided into 4 groups(n = 12 teeth) and treated with different gingival retraction methods: Ultrapak E(group UL) and three kinds of cordless gingival retraction, including Expasy1 (group EX), Astringent Retraction Paste (group AS) and Racegel(group RA). Perfusing plaster models were prapaired after useing putty-wash impression technique. A 3D digital model was reconstructed by a 3-shape model scanner for each patient. Data were collected before and after gingival retraction and analysed by the Geomagic Studio 2013 in the mesial, middle, and distal sides of the selected teeth. Results: Effective width of gingival retraction were all obtained in the 4 groups. The most effective effects were observed in group UL, followed by group EX, group AS and group RA, among the groups, F = 1 114. 4, P＜ 0. 000 1. Conclusion: Cordless gingival retraction technic can achieve effective gingival retraction.