Effect Of Preheating On Surface Roughness And Microhardness Of A Nanohybrid Composite Resin - An In Vitro Study

Introduction: The success of dental composites in restorative dentistry stems from their good aesthetic properties andadequate durability. The clinical performance of composite resins is directly related to the degree of monomer conversion afterphoto polymerization. Placing composites at an elevated temperature reduce their viscosity and increase the efficiency ofpolymerization. Heating the composite prior to placement in the cavity increases monomer conversion rate and therefore theduration of the irradiation period may be reduced.Purpose of Study: Evaluate and compare effect of pre-heating on surface roughness and microhardness of nanohybrid compositeresin subjected to two different temperatures and two different durations using light emitting diode curing unit (LED LCU).Methods: Nanohybrid composite resin was tested at two temperatures (37°C and 55°C) and pre-heating of composite wasdone using incubator at two durations (10 and 20 minutes) respectively. Samples were injected into cylindrical Teflon molds andthe top surface of the specimens were polymerized using LED LCU for 40 s. After preservation for 24 h, specimens checkedfor surface roughness and Vickers hardness measurements. Statistical analysis were performed using one-way analysis ofvariance and Tukey post hoc test at a level of significance of P < 0.05 for both surface roughness and microhardness.Results: Pre-heating of composite affect on microhardness and did not influence on surface roughness.Conclusion: Pre-heating of resin composite increases microhardness and no significant effect on roughness.