Effects Of Post Space Preparation And Different Post And Core Cement Systems On The Microleakage Of Treated Residual Roots

Objective: The purpose of this study was to study the effects ofimmediate and delayed post space preparation on the sealing ability offilling materials and to compare the apical and coronal microleakage ofdifferent post and core systems bonded with various luting cementsthrough measuring the dying length in root canals.Method: Eighty human mandibular premolars each with singlecanal were choosed. They were devided into five groups randomly. Fivefor positive control group, five for negative control group, twenty for immediate post space preparation group, another forty teeth used fordelayed post space preparation group and the last ten for intact group. Allteeth except the positive control group were obturated with laterallycondensed gutta-percha and AH-Plus sealer. After immediate and delayedpost space preparation was performed, all teeth were restored withdifferent post and core systems using various luting cements. Leakagealong root canals was determined by the dye method.Result:1. There is significant difference between two groups using immediate and delayed post space preparation. More leakage is found in canals with delayed post space preparation (1.15±0.65mm) than those with immediate post space preparation (0.50±0.45mm) (P<0.05).2. Canals with 5mm filling materials only cause more leakage. There is significant difference between roots with delayed post space preparation (1.17±0.77mm) and intact ones (0.24±0.43mm) (P<0.05). However, no statistical difference can be found between roots with immediate post space preparation (0.52±0.47mm) and intact ones (0.24±0.43mm) (P>0.05). 3. Compared to metal posts adhered with composite resin cement (0.70±0.49mm), those adhered with zinc phosphate luting agent (3.94±0.45mm) have more leakage (P<0.05).4. No significant difference can be found between two groups bonded with the composite resin cement (metal post: 0.70±0.49mm; glass-fiber post: 0.64±0.46mm) (P>0.05).5. Roots restored with any post and core system (glass-fiber post: 0.64 + 0.46mm; metal post and core bonded with composite resin cement: 0.70±0.49mm; metal post and core bonded with zinc phosphate luting agent: 3.94±0.45mm) have better sealing ability than those sealed by temporary materials (8.28±0.71mm) (P<0.05).Conclusion:1. Delayed post space preparation has more effect to the apical sealing ability than immediate post space preparation.2. The use of post and core systems can retrieve the disadvantages taking by post space preparation and provide better sealing ability for canals.3. Luting agent can decrease the coronal microleakage. Composite resin cement provides better sealing ability than zinc phosphate luting agent.