Methods: We determined sorption, solubility, and flexural and compressive strength and hardness according to ADA Rule 27. For exothermic reaction, the specimens were placed in a differential scanning calorimeter (DSC) as cured. For the degree of conversion, samples were maintained at 37°C for 10 min after mixing, then stored in de-ionized water and studied at different times. The degree of conversion was determined by infrared spectrophotometry, and the values obtained from the peaks were related mathematically.
Results: Systemp C&B® showed better results, with lower flexural strength, water sorption, and solubility compared with those of the other 2 resins used. Luxatemp AM Plus® presented the highest values of hardness and compressive strength, and hardness increased with increasing length of storage. Systemp C&B® showed no exothermic reaction, but all resins showed temperatures detrimental to pulp. Bis-acrylic resins, when they reach their maximum degree of conversion, decreased with time. The degree of conversion was different in the 3 brands of bis-acrylics, decreasing with time, and was higher about 4 hours after mixing. The more stable brand was VersaTemp.
Conclusion: Each brand of resin has its advantages, and should be selected depending on the clinical needs of dentists.