Evaluation of Linear Dimensional Stability of Various Denture Base Resins subjected to Sterilization by Microwave Irradiation: An Invitro study

INTRODUCTION: In dental clinic, during repair work, relining or adjustment procedures dentists, dental assistants and dental office environment commonly comes in contact with the dentures. These dentures may be infected with loads of bacteria, fungi and viruses. The microorganisms adhered to the denture surface create a potential source of contamination from patients to dental and laboratory personnel. Thus, to reduce the chances of cross-contamination in the dental environment, dentures should be completely disinfected before being sent to the laboratory. Patients with poor denture hygiene exhibit denture stomatitis. AIMS AND OBJECTIVES: The aim and objective of this study was to evaluate the dimensional stability of previously polymerized different denture base resins subjected to sterilization by microwave irradiation. MATERIALS AND METHODS: Three different types of denture base resin materials were used in this study – 1. Heat cure acrylic resin 2. Injection molding acrylic resin 3.Flexible acrylic resin. 120 bar shaped samples of dimension 64x10x3.3mm3 were prepared from three types of denture base resins with 40 samples in each group. Half of these samples were tested for their dimensional stability using digital vernier calliper subjected to microwave irradiation at 650W and 810W for 3 minutes. Another half samples were checked for sterilization. By coating candida albicans and subjected to microwave oven at 650W and 810W for 3 minutes. RESULTS: In conventional heat cure resin, injection moulding resin and flexible acrylic resin there was change in the linear dimensional stability after subjected to microwave irradiation at 650W and 810W for 3 minutes and there was statistically significant change in linear dimensional stability for conventional heat cure resin, injection moulding resin and flexible acrylic resin. Power levels caused less distortion of 0.003 – 0.01% which is below the clinical limit of 1 %.In this study the presence of Candida albicans in acrylic samples was investigated using Sabouraud Dextrose Agar. The results revealed that there is no growth of Candida albicans when the medium directly streaked with Candida albicans. The growth was shown only in control. CONCLUSION: The findings of this investigation suggest that microwave irradiation may be a potential treatment to prevent cross contamination between the dental office and dental laboratory. Microwaving for 3 min was an effective method for clinical sterilization of acrylic dentures. There is change in the physical properties of the acrylic resin materials, but within the acceptable changes. The complete sterilization of the acrylic resin is at 650W and 810W for 3 minutes. The power used for sterilization of the acrylic samples can be set at 650W for 3 minutes