ABSTRACT
Disinfection of dental impressions is a weak point in the dental hygiene chain. In addition, dental office personnel and dental technicians are endangered by cross-contamination.This study aimed to investigate the dimensional stability of two color-changing irreversible hydrocolloid materials [IH] after disinfection with glutaraldehyde.In this in vitro study, impressions were made of a master maxillary arch containing three reference inserts on the occlucal surface of the left and right maxillary second molars and in the incisal surface of the maxillary central incisors. Two types of color-changing irreversible hydrocolloid [tetrachrom, cavex] were used. Glutaraldehyde 2% was used in two methods of spraying and immersion to disinfect the impressions. The control group was not disinfected. Casts were made of type IV gypsum. The linear dimensional change of the stone casts was measured with a profile projector. For statistical analysis, Kruskall-Wallis and Mann-Witney tests were used [alpha=0.05].By immersion method, the casts fabricated from tetrachrom were 0.36% larger in the anteroposterior [AP] and 0.05% smaller in cross arch [CA] dimensions; however, the casts prepared after spraying of tetrachrom were 0.44% larger in the AP and 0.10% smaller in CA dimensions. The casts made from Cavex were 0.05% smaller in the AP and 0.02% smaller in CA dimensions after spraying and 0.01% smaller in the AP and 0.003% smaller in CA dimensions after immersion. Generally there were not significant differences in AP and CA dimensions of the experimental groups compared to the control [p > 0.05].Disinfection of the tested color-changing irreversible hydrocolloids by glutaraldahyde 2% did not compromise the accuracy of the obtained casts
ABSTRACT
The effect of mouth washes on discolouration of dental ceramics with different surface preparations is not well documented. This in-vitro study has been conducted to evaluate the effect of chlorhexidine [CHX] mouth rinse on colour stability of overglazed [OP], autoglazed, [AP] or polished porcelain [POP] specimens. The restorative material investigated in this study was overglazed, autoglazed, or polished feldspathic porcelain. A total of 48 cylandrical specimens were prepared, [n=16 per each group]. After baseline colour measurements, for a period of14 days 8 specimens of each group were immersed in 15 ml of 0.2% chlorhexidine mouth rinse twice daily for 2 min. After each immersion, the specimens were washed and stored in artificial saliva. Half of the specimens from each group were selected randomly as controls and stored in artificial saliva that was changed daily. The colour change [delta E] of the specimens was measured by a spectrophotometer device. Data were statistically analyzed using 2-Way ANOVA followed by Tukey test All the specimens displayed colour changes after immersion in chlorhexidine mouth rinse. POP specimens exhibited more colour change compared to AP and OP specimens [P=0.001]. AP and OP specimens showed relatively the same colour change which was not significant compared to the control groups [P=0.9].Auto-glazed and over-glazed porcelain can tolerate chlorhexidine mouth rinse better than polished porcelain. However the colour changes of the ceramic with three different surface preparations were not perceivable clinically