Influence of the processing technique on the flexural fatigue strength of denture base resins: An <i>in vitro</i> investigation

Background : Though acrylic resins possess many desirable properties, denture fracture due to flexural fatigue or impact failure is a common problem. One major factor influencing the flexural fatigue strength of denture base resins is the processing technique used. Aim: To measure the flexural fatigue strength of denture base resins polymerized using short and long curing cycles using water bath, pressure cooker, and microwave polymerization techniques. Materials and Methods: Flexural fatigue strength of 60 samples (n=10) were measured using a cyclic 3-point loading method on a dynamic universal testing machine. Data were analyzed using a Student &#x2032;t&#x2032; test. Results : Comparative evaluation using Student&#x2032;s &#x2032;t&#x2032; test of mean flexural fatigue strength of samples processed by water bath processing (660.6) and the microwave technique (893.6) showed statistically significant (P &lt; 0.01) result with microwave processing being higher. Comparison of water bath (660.6) and pressure cooker (740.6) processing and microwave (893.6) and pressure cooker (740.6) processing using Student&#x2032;s &#x2032;t&#x2032; test was not statistically significant (P &gt; 0.05). In the intra-group analysis, it was found that there was statistically significant difference in samples processed using the short and long curing cycle, the latter being better in all groups, P-values being &lt; 0.05, &lt; 0.001, and &lt; 0.001 for water bath, microwave, and pressure cooker polymerization techniques, respectively. Conclusion : The polymerization procedure plays an important role in influencing the flexural fatigue strength of denture base resins, and the microwave long curing processing technique produced denture bases with highest flexural fatigue strength.