Objective To evaluate the retractive effects of different gingival retraction agents. Methods Thirty subjects with healthy gingival conditions were recruited to the trial, and the buccal gingival sulcus of the hibateral first max-illary premolars of each subject（n=60） were treated randomly with one of the six agents—Group A was tetrahydrozoline hydrochloride, Group B was oxymetazoline hydrochloride, Group C was epinephrine hydrochlorid, Group D was AlCl3, Group E was Fe2（SO4） 3, and Group F was normal saline as control. Both pre-treated and post-treated accurate impressions of buccal gingival sulcus of the experimental teeth were made, so were the anhydrite casts. The casts of experimental teeth were sectioned into 2 mm slices bucco-lingually at the buccal eminence. Then the width of the sulcus was measured as the distance from the tooth to the crest of the gingival under a low-power microscope to compare the effect of these gingival retraction agents. Results The width of gingival sulcus became larger after the treatment in all groups（P0.05）. There was no statistically signification between Group D and Group E（P>0.05）, neither was there any statistically significance between Group A and Group B（P>0.05）. Conclusion Tetrahydrozoline manifested excellent effect of gingival retraction.
