| Purpose Canal sealer, used as an assistant material during the root canal filling, plays an important role in obturation, especially at the apical part. This paper will investigate the influence on the apical sealability generated by the root canal sealer placement and distribution.Method 100 single root exsomatized teeth were selected as samples. They were randomly divided into 5 groups, including 3 experimental groups (A, B and C groups) and 2 control groups (D and E groups). All the canals were prepared by the Protaper NiTi apparatus to F3, and were obturated by the Cold Lateral Condensation Method. Sealer was placed by different placement methods in different groups. After the obturation, using the GOD method to detect the apical leakage of the samples, and using standard solution in reagent kit as a control. Apical microleakage solution of each sample in different days (1st, 2nd, 4th, 7th, 10th, 15th, 20th, 25th, and 30th) were selected respectively to detect the sugar viscosity, so as to assess the apical sealability difference among different groups and the varying trend of the apical sealibility in the same group at different times. Meanwhile, using the Cross-Section Method to prepare the canal transverse sections and then scanning them under a stereomicroscope. The sealer distribution was thus categorized in the Image Analysis System to assess the statistic difference of sealer distribution in different groups. Therefore we can investigate the influence on the apical sealability generated by different sealer placement methods and consequently different sealer distributions.Result①In the GOD test, group A-the chief gutta percha group—demonstrated the best sealability, and had statistic difference with other groups (p＜0.05). There was no difference between the two subgroups in group A (P＞0.05). This result indicated that sealer placement by the chief gutta percha can result in the best apical sealability in terms of the instant sealability.②There were inter-group differences at the early stage of the experiment(P＜0.05); however, as the test went on, the differences had no statistic significance anymore (P＞0.05). @In the distribution observation, there were inter-group differences only at the 1mm level (P＜0.05). At the 2mm and 4mm level, sealer distributions had no difference (P＞0.05).④st the lmm level, group Aa mainly expressed aⅣ-type distribution, while Ab mainly expressed aⅡ-type distribution; group B had an average distribution; group C mainly expressd aⅣ-type distribution.⑤There was no difference (p＞0.05) of the apical leakage during the whole experiment at the 4mm level, despite different sealer distributions; at the 1mm and 2mm level, there were inter-group sealability differences at the beginning stage of the experiment, (p＜0.05), but the differences were diminishing as the experiment went on(p＞0.05). The closer the sealer distribution is to the "complete coverage", the better sealability is.In different sealer placements, sealer distribution had differences and high variability only at the 1mm level.Conclusion There's no relationship between the sealer distribution and the apical leakage (p＞0.05). The investigation indicated that the closer the sealer distribution is to the "complete coverage", the better sealability is.In order to get a better instant apical sealability and simplify the clinic operation, it is recommended to place the sealer with a chief gutta percha while using the vice gutta percha without sealer. |
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