DIMENSIONAL STABILITY AND DETAIL REPRODUCTION OF IRREVERSIBLE HYDROCOLLOID AND ELASTOMERIC IMPRESSIONS DISINFECTED BY IMMERSION

Statement of problem. Because irreversible hydrocolloid impressions im bibe blood and saliva, immersion rather than spray disinfection map be more effective. Polyether has been shown to be dimensionally sensitiv e to immersion disinfection. Purpose. The aim of this study was to det ermine whether irreversible hydrocolloid and polyether impressions cou ld be disinfected by immersion without sacrificing accuracy and surfac e quality. Material and methods. Impressions were made of a master man dibular arch containing a crown preparation. Changes between the maste r and working casts were assessed. Irreversible hydrocolloids (Jeltrat e; Palgaflex), a polyether (Impregum F), and an addition silicone (Pre sident) were used. Disinfectants were an iodophor (Biocide), a glyoxal glutaraldehyde (Impresept de), and a phenol glutaraldehyde (Sporicidi n). The control was without disinfection. Casts were formed in Type IV gypsum. The roughness of working dies was also recorded and an analys is of variance was used for statistical evaluation Results. Casts from disinfected irreversible hydrocolloid and elastomeric impressions mai ntained accuracy for anteroposterior and cross arch dimensions where d ifferences from the master was less than 0.1%. Buccolingual and mesiod istal dimensions of working dies (disinfected and control) were 6 to 8 mu m larger than the master for addition silicones and 11 to 16 mu m for polyethers. The occlusogingival dimension of dies for control and disinfected polyether was 9 mu m longer than the master compared with -3 mu m for addition silicone. The range of mean surface roughness of working dies made from irreversible hydrocolloids was 1.4 to 1.7 mu m and ranged from 0.5 to 0.7 mu m for elastomeric impressions. Conclusio n. Immersion disinfection of Jeltrate material with iodophor and Palga flex material with glyoxal glutaraldehyde produced casts and dies as a ccurate as the control. Control and disinfected elastomeric impression produced dies as clinically accurate and smooth as the master. Disinf ection of irreversible hydrocolloid impressions with the glyoxal and p henol glutaraldehyde produced a surface smoother than controls.