Bakteriendichtigkeit von Wurzelkanalfüllungen nach Einsatz verschiedener Obturationstechniken – Eine In-vitro-Studie

Bacteria and their byproducts are the most common cause in the pathogenesis of endodontic diseases. A long-term success of endodontic treatment is therefore only attainable if a permanent sealing against bacteria of the endodontically treated root canal can be achieved. The objective of this in-vitro study was to examine the quality influence of different obturation techniques on the apical seal of root canal fillings of AH Plus and guttapercha, based on a bacterial penetration test. 44 human anterior and posterior teeth with a single straight root canal and a round root canal cross-section were selected. The sample was divided into 4 randomized groups of 10 teeth, and positive and negative control groups of 2 teeth each. The grouping was based on the four selected obturation techniques: single cone technique (SCT), lateral compaction technique (LCT), non-compaction technique (NCT) and Thermafil (TT). The sample teeth were cut to a uniform length of 10 mm before the root canals were enlarged to .04/ #45, using the FlexMaster and ProFile instruments. An intermittent flushing with sodium hypochlorite (5 %) was followed by a final rinsing sequence that consisted of sodium hypochlorite (5 %), citric acid (40 %) and ethanol (70 %). The root canals were dried before the AH Plus sealer was placed with the EZ-Fill Bi-directional spiral for the cold-filling techniques, and by means of paper points, respectively, for the Thermafil group. Depending on the filling-technique, teeth were still filled with a masterpoint, a masterpoint and accessory points or using a Thermafil obturator. After a 28-day curing period, the root surfaces of all sample teeth were sealed with cyanoacrylate, with the exception of 1-2 mm apical and coronal interface. Subsequently, the sealed sample teeth were mounted in a dual chamber system. After the lower chamber was filled with a clear broth, the entire experimental setup was sterilized. The experimental setup was completed by incubation of the upper chamber with a suitable lactobacillus culture. From this point, the bacterial permeability of each sample was monitored and recorded daily. If any of the lower chambers showed turbidity of the culture medium, bacterial penetration had taken place. The observation period was set to 180 days. The statistical data analysis of the penetration times was performed using SPSS 22.0. In the observation period of the present in vitro study, a statistically significant correlation between the filling-techniques and sealing ability of a root canal filling was shown. At the end of the observation period, 31 out of 40 samples were penetrated by bacteria. The first turbidities were observed in the single cone group. The non-compaction group showed similar penetration times. A better perfomance was recognized in the lateral compaction and Thermafil groups. It was shown that the combination of guttapercha and AH Plus using the lateral compaction has the lowest bacterial permeability and can therefore be recommended for clinical application. Thermafil as a modern warm-filling technique shows up in the test results as a potential alternative. Neither the non-compaction technique nor the single cone technique can be recommended on the basis of the present findings for practical use.