Extent of microleakage in relation to root canal morphology

The purpose of this study was to study with standardized methods the length and extent of the microleakage developing around the root canal fillings. The preparational errors were evaluated in twenty straight and curved root canal using computer graphic analysis. The step back technique was used for root canal preparation. The shape of the instrumented root canals were analyzed macroradiographically in order to evaluate unwanted procedural root canal deformities. The root canals were obturated with lateral condensation technique using AH-26 sealer and guttapercha points. After the teeth having been made transparent a silver nitrate penetration test was performed in vacuum and both the linear dye penetration and the extent of dye penetration surface area were measured from four directions with computer assisted digitized method. The linear dye penetration values were higher in straight root canals than in curved ones: 2.22 + 1.17 mm and 1.81 + 1.24 mm respectively. The dye penetration surface area was slightly also larger in straight than in curved root canals: 1.3 +/- 0.71 mm2 vs. 1.06 +/- 0.5 mm2. Nevertheless the differences were statistically non significant. In curved root canals the highest dye penetration values were measured at the inner curvature of the canals. This findings was also corroborated by a coincidence test.