Comparative Evaluation of the Antimicrobial Efficacy of Three Immersion Chemical Disinfectants on Clinically Derived Poly(Vinyl Siloxane) Impressions.

PURPOSE: To comparatively evaluate the antimicrobial efficacy of freshly prepared electrolyzed oxidizing water (EOW) with that of 2.4% glutaraldehyde (GA) and 1% sodium hypochlorite (SH) on clinically derived poly vinyl siloxane (PVS) impressions. MATERIALS AND METHODS: Four clinically derived PVS impressions each were obtained from 10 subjects. One impression from each subject was randomly kept as control (group I), without disinfection. The remaining three impressions were randomly disinfected by immersion in either 2.4% GA (group II), 1% SH (group III), or freshly prepared EOW (group IV). The samples were subjected to microbial culture individually on brain heart infusion (BHI) agar medium. The organisms isolated were confirmed by visual examination and gram staining. Mean colony forming units (CFU) were counted, log10 reduction obtained and compared. Data were statistically analyzed using one-way ANOVA, followed by multiple comparisons using Tukey-HSD post hoc tests (p < 0.05). RESULTS: Streptococci, Staphylococci, Pseudomonas, Candida, Proteus, Klebsiella, and E. coli were isolated from all impressions including the controls, except those disinfected by EOW. All three disinfectants showed significant reduction in CFU and log10 reduction values as compared to the controls. EOW showed significantly higher reduction in log10 values compared to GA and SH, whereas GA and SH showed similar reductions. EOW, GA, and SH showed kill rates of 100%, 99.60%, and 99.82%, respectively. CONCLUSION: EOW showed significant antimicrobial efficacy as evidenced by reduction in log10 values when used as an immersion disinfectant for PVS impressions when compared with the results obtained using GA and SH. These results need further investigation. CLINICAL IMPLICATIONS: EOW shows high antimicrobial efficacy when used as an immersion disinfectant as compared to GA and SH for clinically derived PVS impressions.

Influence of Surface Modifications of Acrylic Resin Teeth on Shear Bond Strength with Denture Base Resin-An Invitro Study.

BACKGROUND: Debonding of artificial teeth from the denture base is an important issue for edentulous patients rehabilitated with conventional or implant supported complete dentures. AIM: The purpose of this study was to evaluate shear bond strength between denture base resin and acrylic resin denture teeth subjected to three different surface modifications on the ridge lap area as compared to unmodified denture teeth. MATERIALS AND METHODS: Forty acrylic resin central incisor denture teeth were selected and randomly divided into four test groups. The teeth in each group were subjected to one of the three different surface modifications, namely, chemical treatment, sandblasting and placement of retentive grooves on the ridge lap area respectively, prior to packing of the denture base resin. The group with unmodified teeth served as control. Forty acrylic resin test blocks thus obtained were tested for shear bond strength between acrylic resin teeth and denture base resin in Universal Testing Machine. Data obtained was statistically analysed using one-way ANOVA and Student- Newman- Keul's test (p< 0.05). RESULTS: Analysis of shear bond strength revealed that retentive grooves on the ridge lap area showed highest bond strength values followed by sandblasting and both were statistically significant compared to the control and chemically treated groups. Unmodified surface of the resin teeth showed the least bond strength. CONCLUSION: Within the limitations of this invitro study the placement of retentive grooves or sandblasting of the ridge lap area showed highly significant improvement in shear bond strength compared to the unmodified surface. Chemical treatment did not result in any significant improvement in the shear bond strength compared to the unmodified surface.