RESUMEN
BACKGROUND: The vibration of high speed handpiece during tooth preparation may have adverse effect on the continuous force of the bonding interfaces among the cement, dentin, and post core. OBJECTIVE: To find the effect of different types of cements on the coronal microleakage of fiber post under different tooth preparation timings, and to provide evidence for the clinical operation. METHODS: The extracted mandibular premolars were divided into 3 groups, and they were cemented by Rely X luting, Panavia F and Paracora 5 mL, respectively. Each group was averagely divided into 3 subgroups: A, B, C groups which were prepared 15 minutes, 45 minutes, and 90 minutes after the cements mixed. All roots were then dyed and transparented. The teeth were observed under stereoscopic microscope and the dyeing scores were also recorded. RESULTS AND CONCLUSION: Rely X luting caused the highest coronal microleakage of fiber post, followed by Panavia F, while Paracore 5 mL, brought about the lowest under the same tooth preparation timing. Different tooth preparation timing caused no significant effect on the coronal microleakage of fiber post when the cement had been completely set.