Effect of calcium hydroxide as intracanal medication on the apical sealing ability of mineral trioxide aggregate (MTA): an in vitro apexification model

Objective - To evaluate the effect of calcium hydroxide premedication on the apical seal of White MTA, placed as an apical barrier in permanent teeth with simulated immature apices. Furthermore, we intended to compare potential changes, under the influence of calcium hydroxide, in the apical seal of MTA over time. Methods - Thirty-four single-rooted extracted teeth were prepared in order to simulate a divergent open apex. Two experimental groups of 10 teeth were created: group 1 (G1) and group 2 (G2) with and without calcium hydroxide intracanal medication previous to the placement of MTA apical plug. Two control groups, positive and negative, each with 7 teeth were created. On the 7th and on the 28th day after placement of the MTA apical plug, the apices of the teeth were submersed in a solution of sodium pertechnetate (99mTcO4Na) for 3 hours. The radioactivity was measured using a gamma camera. Results - Results revealed statistically significant differences between the 2 control groups and the 2 experimental groups with respect to the microleakage. Within the experimental groups no statistically significant differences were found; nor between the two observed periods. Conclusion - Based on the results obtained in this study, it was concluded that intracanal medication with calcium hydroxide did not affect the sealing ability of WMTA, placed as an apical plug, neither on the 7th, nor on the 28th day. Objetivo - Avaliar o efeito do hidroxido de calcio como medicacao intracanal, no selamento apical do MTA branco, colocado como uma barreira apical em dentes permanentes com apices imaturos simulados. Metodos - Trinta e quatro dentes unirradiculares extraidos foram preparados para simular um apice aberto divergente. Foram separados em dois grupos experimentais (n=10): G1 e G2 com e sem medicacao intracanal de hidroxido de calcio antes da colocacao do tampao apical com o MTA e dois grupos controle, positivos e negativos (n=7 em cada). Em 7 e 28 dias apos a colocacao do tampao apical de MTA, os apices dos especimes foram submersos em uma solucao de pertecnetato de sodio (99mTcO4Na) por 3 horas. A radioatividade foi medida usando uma câmara gama. Resultados - Os resultados revelaram diferencas estatisticamente significativas entre os grupos controle e os grupos experimentais com relacao a microinfiltracao. Nao houve diferenca entre os grupos experimentais nos dois periodos. Conclusao - Com base nos resultados obtidos neste estudo, concluiu-se que a medicacao intracanal com hidroxido de calcio nao influenciou na capacidade seladora do MTA.