Influence Of Root Canal Irrigants And Cements On The Coronal Microleakage After Cementing Metal Post-Cores

Objective:Microleakage ocuuring at the poor sealing interface of restoration-dentin might go against long-term effect of post-core restoration. It is a frequent cause of development of some bad consequences, such as secondary caries, restorations loose off and so on. After post space preparation, large arears of the canal walls were covered by smear layer and rough debris which might impact the cementing effect between luting agent and dentin walls. Now zinc polycarboxylate cement and glass ionomer cement are commonly used in cementing of metal post-cores in clinic. However there was no definite way to clean dentin walls before cementation, only wiping it with alcohol sponge.In the experiment, two root canal irrigants and alcohol sponge were used in cleaning the dentin walls and then metal post-cores were cemented with zinc polycarboxylate cement and glass ionomer cement respectively. The microleakage degrees were compared among six defferent groups, using dye penetration. Evaluation of root canal irrigants and cements on the coronal microleakage after cementing metal post-cores would provide a reference for clinical applications.Methods: Ninety newly extracted single-rooted mandibular human premolars were endodontically treated. Post spaces were prepared in the root canals and Co-Cr post-cores were cast routinely. All the specimens were randomly divided into six groups (n=15), according to the irrigants and cements used. Group A(control group): alcohol wiping and zinc polycarboxylate cement; Group B(control group):alcohol wiping and glass ionomer cement; Group C:3%H2O2+0.9%NaCl and zinc polycarboxylate cement; Group D:3%H2O2+0.9%NaCl and glass ionomer cement; Group E:15%EDTA+5.25%NaOCl and zinc polycarboxylate cement; Group F:15%EDTA+5.25%NaOCl and glass ionomer cement. All the samples were sectioned longitudinally after being immersed in India ink for3weeks. The microleakages were observed under a stereomicroscope. SPSS13.0software package was used for factorial analysis.Results:1. The mean microleakage scores and standard deviations were as follows:Group A:1192.59±417.84um, Group B:1317.38±527.35um, Group C:1429.33±482.68um, Group D:1026.79±459.49um, Group E:1448.29±561.02um and Group F:1922.47±678.86um. An interactive effect on the microleakage existed between the irrigants and the cements after cementing the metal post-cores (P=0.007).2. The differences between group A and group B had no statistical significance (P>0.05). The microleakage degrees of the two groups using the same root canal irrigant can be observed:group C> group D, group F>group E, and there were statistically significant differences (P<0.05)3. As for zinc polycarboxylate cement, no statistically significant differences were found among the three groups (P>0.05). And as for glass ionomer cement, there were significant differences among the three groups (P<0.05), but no significant differences was noted between group D and group B (P>0.05)Conclusion:Under the restricted experimental condition of this study, we can conclude that: 1. After the dentin walls were cleaned by different methods and two cements were used to cement Co-Cr post-cores, all the samples have occured obvious microleakge.2. When cementing metal post-cores, the coronal microleakage following3%H2O2+0.9%NaCl irrigation combined with glass ionomer cement can be reduced to some extent.3. The combined application of15%EDTA+5.25%NaOCl and glass ionomer cement aggravates microleakage significantly.