The Effect of Two Denture Cleansers on Surface Roughness and Hardness of a

The denture cleansers used daily by patients can damage soft denture liners. The goal of this study was to determine the surface roughness and hardness of a silicone soft liner, Gc-Reline, after immersion in calgon+sodium hypochlorite or in 1% sodium hypochlorite solutions. In this in vitro experimental study, 63 ring shaped specimens of silicone soft liner (14mm in diameter and 2mm thickness) for hardness test and 63 specimens (31mm in diameter and 10mm thickness) for surface roughness test were prepared. The specimens were divided into 3 equal groups (no=21) for each test. Then each group was subdivided into 3 subgroups according to time of immersion in cleansers (no=7). Each subgroup was soaked 8 hours per day in distilled water (W), calgon-sodium hypochlorite (C) or in 1% Sodium hypochlorite (H) solutions for 1, 30 and 60 days. Roughness was measured in micrometer by a profilometer and hardness was assessed using Shore A test apparatus. The data were analyzed using Two-Way ANOVA test. No change was observed in surface roughness (µm) and hardness of silicone samples after 1, 30 and 60 days immersion in water (W) but in comparison to control group, surface roughness of samples in both cleansers was increased significantly in all time period of the study (P<0.05). Hardness of silicone specimens after 1, 30 and 60 days immersion in C group did not change but after 60 days soaking of samples in H solution, hardness was enhanced significantly (P<0.05). Both solutions of calgon+hypochlorite sodium and 1% hypochlorite sodium increased surface roughness of silicone liners. This increase was higher in 1% hypochlorite sodium solution. The 1% hypochlorite solution increased hardness of silicone soft liners after 60 days. No change in hardness was observed in other time period of this study. r.