Comparative Evaluation of Tensile Strength in Die Stone Incorporated with Sodium and Calcium Hypochlorite as Disinfectants: An in vitro Study.

AIM: The aim of this study was to evaluate the tensile strength of die stone incorporated with sodium and calcium hypochlorite as disinfectants. MATERIALS AND METHODS: Two commercially available type IV die stone (Kalrock: Kalabhai Karson Pvt., Ltd and Pearlstone: Asian Chemicals) and two commercially available disinfectant solutions (sodium hypochlorite and calcium hypochlorite: Beachem Laboratory Chemical Private Limited, Chennai and Leo Chem Private Limited, Bengaluru) were used in this study, and the tensile strength was measured using Lloyd's Universal Testing Machine. RESULTS: The results show that incorporating the disinfecting solutions decreases the tensile strength of both products. The effect of decreasing tensile strength on type IV gypsum product is seen more in calcium hypochlorite when compared with sodium hypochlorite disinfecting solution, and the tensile strength of Kalrock specimens is higher than Pearlstone specimens after disinfecting with sodium hypochlorite and calcium hypochlorite solution. The statistical results also show significant results in all the groups when compared with the control group. CONCLUSION: The incorporation of sodium and calcium hypochlorite disinfecting solutions is not an encouraging method for both die materials as it reduces the tensile strength of type IV gypsum product. Tensile strength of Kalstone® die material is superior than Pearlstone® die material after mixing with sodium hypochlorite and calcium hypochlorite. CLINICAL SIGNIFICANCE: According to the recommendations of Americans with Disability Act (ADA) and the Centers for Disease Control and Prevention, disinfecting the whole cast without or minimal changes in physical and mechanical properties was the motto of the study. The tensile strength in type IV gypsum product plays a most important role in retrieval of cast from impression, especially in narrow tooth preparation. This study reveals that incorporating method of disinfecting solutions is not recommended as it reduces the tensile strength.

Efficacy of Denture Cleansers on Impact Strength of Heat polymerized Acrylic Resins.

PURPOSE: The study was aimed to compare and evaluate the changes in the impact strength of heat cure denture base resins when treated using denture cleansers. METHODOLOGY: Study was conducted with sample size of 40 and dimesion 65 mm length, 10 mm width, and 3 mm thickness as per the ISO 1567. Distilled water has been used as control group, in which 10 samples were immersed of 40 samples. Of remaining 30 samples, 10 were treated with Clinsodent, 10 were treated with VI-Clean, and 10 were treated with Clanden denture cleansers. The impact strength of these specimens from each group was tested with the help of Charpy-type pendulum impact strength tester. The energy absorbed to fracture the specimens was recorded, and impact strength was calculated and was analyzed using Kruskal-Wallis ANOVA and Mann-Whitney test. RESULTS: Impact strength of samples was significantly reduced after immersion in denture cleansers Clinsodent, VI-Clean, and Clanden solutions when compared to control group. CONCLUSION: Clinsodent, VI-Clean, and Clanden denture cleansers decrease the impact strength of heat cure denture base resin after immersion. Hence, the study concludes that denture cleansers should be used with caution and advised to follow manufacturer's instructions.