COMPARISON OF IMPACT STRENGTH OF MICROCRYSTALLINE CELLULOSE REINFORCED DENTURE BASE ACRYLIC RESIN WITH AND WITHOUT THERMOCYCLING

Abstract

Objective: This study sought to investigate the impact strength of polymethyl methacrylate when reinforced with varying quantities of microcrystalline cellulose (MCC) with and without thermocycling in vitro. Materials and Methods:  A total of 30 meticulously samples were prepared and tested according to the ISO 179A1:2005 specifications. The control group was prepared, following the manufacturer’s instructions, with no MCC reinforcement. Experimental groups were categorized into two sub-groups, reinforced with 2% and 5% MCC. The samples from each group were further divided into two sub-groups (with thermocycling and without thermocycling), while half of the samples from each sub-group (n=5) were thermocycled for 5000 cycles at 5 °C and 55 °C with a dwell time of 30 sec on each cycle. The other half of each group (n = 5) were left submerged in water for 48 h without being thermocycled. Specimens were separately labelled and subjected to impact strength testing using Zwick pendulum impact tester. Results: Prior to thermocycling, the addition of MCC to the acrylic denture base resin significantly increased its impact strength, as supported by a One-Way ANOVA that demonstrated a significant difference in impact strength proportional to the amount of added cellulose (P ≤ 0.05). After thermocycling, group B1, reinforced with 2% MCC, showed the highest impact strength as compared to the control group A1 and group C1, reinforced with 5% MCC. Conclusion: The impact strength of the 2% cellulose-reinforced group exceeded that of control group, both before and after thermocycling. Conversely, the impact strength of the 5% cellulose-reinforced group was lower than other groups, as the MCC amount was increased, the impact strength decreased before and after thermocycling.