Disinfection Effect on Linear-Dimensional-Change and Detail-Reproduction of Hydrophilic PVS Impressions

Objectives:To evaluate the efficacy of three disinfectants and two disinfecting methods, either spray or immersion, on newer generation hydrophilic vinyl-polysiloxane and polyether impression materials and to validate that the disinfecting methods provide no negative impact on the materials through an evaluation of the Linear Dimensional Change(LDC) and Detail reproduction(DR).

Methods:The materials used were: Examix(GC America), Genie(Schein), Take1(Kerr), Aquasil(Dentsply) and Impregum(3MESPE), TypeIII light-body consistency(ISO4823:2000). Three Types of disinfectants were used:Ecotru(parachlorometaxylenol0.20%), Prospray(O-Phenylphenol0.28%,O-benzyl-p-chlorophenol0.03%) and bleach(Sodium hyprocholrite5.52%-diluted 1:10 with distilled sterile water). Testing included both spray and immersion disinfection processes(10 minutes of exposure). 525 specimens were made in a stainless steel master die (38 mm x 6mm x 6mm); the distance between two indentations was used to measure the (LDC). (DR)was assessed by the ability of the stone to reproduce fifteen lines of various widths ISO4823:2000. Comparisons were made between the LDC & DR of controls and that of disinfected groups of each impression material using a three-way and two-way ANOVA test(P= 0.05)

Results:The three-way ANOVA analysis for the LDC showed that the type of disinfectant, method of disinfection, and impression material did not result in a statistically significant change in the LDC. The two-way ANOVA analysis for Take1 showed that (1) the type of disinfectant had a statistically significant effect on the LDC(P-value=0.037) when used with Bleach, (2) the disinfection method had a statistically significant effect on the LDC for the sprayed Aquasil impression(P-value=0.027). The average lines reproduced for DR dramatically deteriorated in both control and disinfected groups. Examix had the worst DR on stone except when used with Ecotru Spray and immersion.

Conclusions:Within the limitations of this in-vitro study, for both LDC and DR, PVS impressions performed exactly the same as the polyether impression; all groups fell within the range required for ISO 4823:2000 and therefore were deemed clinically acceptable.