| dc.description.abstract | Objective
Improving the dental discoloration in the teeth with root canal treatment is possible by bleaching the tooth with walking technique, but release of the hydroxyl ion from the bleaching materials leads to the root cervical resorption. Hence, it is necessary to use the cervical barrier materials to prevent this issue. The present study investigates the sealability of different endodontic biomaterials as the cervical barrier in the internal bleaching with walking technique and high performance liquid chromatography method.
Materials and methods
90 single-rooted and single-canal premolars of the human mandibular were selected and once they were cleaned and formed inside the canal by the rotary system, the teeth canals were obturated by gutta-percha and AH26 sealer. Once the sealer was set, root canals were unloaded by heat carrier up to 3 mm under the CEJ area. In each of four studied groups (n = 20), the cervical barrier materials of MTA, CEM, Biodentine and MTA+PG were placed up to the CEJ area. As the teeth were incubated for 24 hours in 37oC, the studied groups were divided into two groups, i.e. A and B, based on the bleaching material. In groups A (n = 10) and B (n = 10), the bleaching materials of sodium perborate + water and sodium perborate + hydrogen peroxide 30%, respectively. In positive control group (n = 5), materials of sodium perborate + hydrogen peroxide 30% were applied without any cervical barrier biomaterials and no materials was used for the negative control group. Once the bleaching materials, the access cavity was covered by wax. Each teeth, then, was put in the CC1 Terephthalic acid solution up to the CEJ area and incubated for 48 hours in 37oC. To determine the amount of free radical leaked from the bleaching material under the CEJ, HPLC fluorescence (FL) detector was used.
Statistical analysis Method
Once the mean and SD (descriptive analysis) of hydroxyl ion released in the studied groups were calculated, normality of data distribution was investigated by Smirnov-Kolmogorov test. To examine the significance of impact of cervical barrier and bleaching material types on the hydroxyl ion, the two-way ANOVA was used. To compare the pairwise groups, Tukey’s post-hoc test was used. Two-way ANOVA was also applied to compare the groups pairwise. Level of significance was taken as P < 0.05 and the statistical analysis was done by SPSS v.17.
Results
On the basis of one-way ANOVA test, there was a significant difference in the concentration of the hydroxyl ion released in the studied groups (P-Value < 0.001).
Results of two-way ANOVA also showed that the amount of hydroxyl ion released among the cervical barrier materials was statistically significant (P-Value < 0.001), but the amount of hydroxyl ion released among the bleaching materials was not statistically significant (P-Value = 0.58).
The amount of hydroxyl ion released was highest and lowest in the positive control group and CEM group, respectively. From among the used biomaterials, MTA+PG had the highest level of leakage. Difference between MTA and Biodentine was not significant (P-Value = 0.266).
Conclusion
Considering the limitations of this study among the applied cases, CEM cement is a more appropriate material to be used as the cervical barrier in the step-by-step internal bleaching method. | en_US |
