IMMERSION DISINFECTION OF IRREVERSIBLE HYDROCOLLOID IMPRESSIONS IN PH-ADJUSTED SODIUM-HYPOCHLORITE .2. EFFECT ON GYPSUM CASTS

Lowering the pH of sodium hypochlorite has been shown to greatly impro ve its efficacy as a disinfectant for irreversible hydrocolloid. This study evaluated the surface roughness and detail reproduction of gypsu m casts recovered from impressions disinfected with sodium hypochlorit e at altered pH levels. The experimental disinfectants were sodium hyp ochlorite 0.525% (10-minute immersion) at pH 11.5 (unaltered), pH 10, and pH 8. An additional group was tested at pH 10 for 5 minutes. There was a trend toward increased surface roughness as the pH was lowered, but a 5-minute immersion of impressions in sodium hypochlorite at pH 10 produced casts of equivalent surface roughness to impressions rinse d in water and poured immediately. The test for surface detail reprodu ction produced similar results.