RESUMO
AIM: To analyze the clinical effectiveness of three new gingival retraction systems: knitted retraction cord, expanding polyvinyl siloxane, and aluminium chloride containing paste. MATERIALS AND METHODS: Twenty patients were enrolled with age-group of more than 18 years and who required fixed prosthesis with minimum of two abutments. A preliminary impression of the arch was made with a stock metal tray and irreversible hydrocolloid impression material. Group WR-impression without retraction, Group A-impression after retraction with gingival retraction cord, Group B-impression after retraction with expanding polyvinyl siloxane, and Group C-impression after retraction with aluminium chloride containing paste. A total of four impressions were made for each abutment tooth. Each impression was given a label 1WR, 1A, 1B, 1C-20WR, 20A, 20B, 20C: where 1 denoted the sample number. Comparison of the stereomicroscopic images was done using image analysis software. Time required from start of placement of gingival displacement agents till completion was recorded in seconds with the help of a stop clock. RESULTS: The mean gingival retraction was found to be the highest for subjects of Group C followed by Group A, Group B, and Group WR. This difference was found to be statistically significant. Highly significant mean difference in time of placement was observed between Group A and Group B, between Group B and Group C, and between Group C and Group A. CONCLUSION: The aluminium chloride containing paste was found effective in almost all the variables considered. CLINICAL SIGNIFICANCE: The choice of particular gingival retraction system/technique is dependent upon the clinical variables and on operator's preference.