A modification of a previous model for inflammatory tooth pain: Effects of different capsaicin and formalin concentrations and ibuprofen

This study aimed to solve the problems faced with the previous model of inflammatory tooth pain in rats. After cutting 2 mm of the distal extremities, the polyethylene crowns were placed on the mandibular incisors. In contrast to the original model, we used flow composite instead of wire in order to maximize the retention of crowns. Different concentrations of capsaicin (10, 25 and 100 mg/ml) and formalin were administrated into the cavities under the crowns. The algesic agent-induced behaviors were evaluated. The modified model had no liquid leakage. Furthermore, composite allowed the crowns to remain for a longer period of time. Capsaicin 25, 100 mg/ml and formalin applications induced significantly more painful stimulation compared with control groups (P < 0.001). These responses were significantly reduced by the administration of ibuprofen, 20 minutes prior to the capsaicin 100 mg/ml injection. This model seems to be adequate for long-term pain related experiments in which fluid leakage elimination is important.