The nociceptive and anti-nociceptive effects of white mineral trioxide aggregate.

AIM: To assess the nociceptive and antinociceptive effects of white mineral trioxide aggregate (WMTA) using the orofacial formalin test in rats. METHODOLOGY: Rats (n = 10 in each group) were separately injected into the ipsilateral upper lip with either 40 microL of a 2.5% formalin solution and eugenol (50 mg kg(-1)) or WMTA (5, 10 and 20 mg dissolved in 0.2 mL saline) alone. In a second experiment to evaluate antinociception effects, 15 min prior to formalin injection, rats were pre-treated with either white ProRoot MTA (20 mg dissolved in 0.2 mL saline) or eugenol. The time each rat spent rubbing the injected site with its paw, as an index of nociception, was recorded for a period of 45 min. RESULTS: Administration of 40 microL white ProRoot MTA (5, 10 and 20 mg per 0.2 mL) alone did not produce any significant nociceptive response. Moreover, prior treatment with WMTA caused significant (P < 0.001) inhibition of formalin-induced nociception. Injection of eugenol (50 mg kg(-1)) provoked the first phase of a nociceptive response, although its intensity was reduced compared with that produced by formalin. Pre-treatment with eugenol significantly (P < 0.0001) inhibited the induction of nociception by formalin. Comparison of the behavioural responses observed in WMTA and eugenol-treated rats alone or in combination with formalin revealed that WMTA did not only induce pain behaviour but also prevented formalin-induced nociception. CONCLUSION: White mineral trioxide aggregate, when compared with eugenol, was more effective in treating nociceptive pain in the orofacial formalin test.

Comparison of neurotoxicity of root canal sealers on spontaneous bioelectrical activity in identified Helix neurones using an intracellular recording technique.

AIM: To evaluate the neurotoxic effects of two endodontic sealers, AH-26 and Roth 801, on firing excitability and action potential configuration of F1 neural cells in the suboesophageal ganglia of Helix aspersa. METHODOLOGY: A conventional intracellular current clamp technique was used to study the blocking effects of AH-26 and Roth 801 on ionic currents underlying the action potential of F1 nerve cells. The sealers were prepared according to the manufacturers' directions and were applied to the bathing media in two ways: invasive (0.05 mL of total mixture of each sealer was applied at a distance of 3 mm from the cell), or gradual (0.05 mL of the extract of each dissolved mixture of sealers in normal Ringers solution was perfused). RESULTS: When applied in an invasive mode, both sealers reduced the duration, the amplitude of action potentials and the amplitude of after-hyperpolarization potentials significantly and led to dramatic changes in action potential configuration. In the gradual mode of application, AH-26 showed a biphasic action; it first increased the excitability and then decreased the action potential parameters, while Roth 801 exhibited solely blocking effects. CONCLUSIONS: Both sealers had significant inhibitory effects on excitability of F1 neuronal cells.