Einfluss verschiedener Obturationstechniken und Sealer auf die koronale Dichtigkeit von Wurzelkanalfüllungen ovaler Wurzelkanäle

1. Summary 1.1 Background and aims The aim of any root canal treatment is a bacteria-tight seal of the root canal filling to its surrounding environment. This is to ensure that there is no reinfection of the root canal. Especially the coronal seal of a root canal filling is of great importance. For this reason, the aim of the work was to investigate the influence of different sealers and obturation techniques on the coronal leakage of root canal fillings of oval root canals using the linear penetration depth. 1.2 Methods For this study, 80 extracted human single-rooted teeth with one root canal and an oval cross section were used, which originated from human extracted mandibular incisors and premolars of the upper and lower jaw. The teeth were divided into 8 groups (n=10). Two different sealers AH Plus™ (Dentsply) and Pulp Canal Sealer™ EWT (Symbron Endo Corporation) were examined using the single cone technique, the lateral condensation technique, the non-compaction technique and Thermafil™ (Dentsply). After an initial reduction to a total length of 12 mm, the teeth were mechanically processed with FlexMaster™ and ProFile™ instruments up to size 45 taper .04. Furthermore, the coronal region of the root canal was extended by 2 mm in oral and buccal direction with diamond SONICflex endo™ tips (KaVo). Also all areas in the canal were manually processed with a Hedstrom file size 45 taper .02. After an alternating irrigation with 2 ml 5% sodium hypochloride and 40% citric acid, and final rinsing with 2 ml 70% alcohol, the root canals were dried using paper points and then obturated with sealers and guttapercha to be examined using the according technique and stored at 37 °C and 100% humidity for 7 days. This was followed by the isolation of the teeth with 2 layers of nail polish. Afterwards, the teeth were dyed in a centrifuge at 300 rpm for 3 min with 5% methylene blue and embedded in epoxy resin. After the preparation of serial sections, the individual layers were examined in terms of penetration depth using the light microscope and then they were statistically analyzed using SPSSwin 14.0 (SPSS Inc.). 1.3 Results In terms of coronal leakage and linear penetration depth determined in this study, significant differences in the use of different obturation techniques were found between the two sealers. In this study, it was found that the proven AH Plus achieved the best results in combination with the lateral condensation (3.44 mm) and the non-compaction technique (3.55 mm), while the warm condensation technique Thermafil (6.57 mm) yielded significantly worse results in combination with AH Plus in this group. From those sealers used in the study, Pulp Canal Sealer performed poorly; only in combination with Thermafil a fairly acceptable linear penetration depth was shown (7.28 mm). 1.4 Practical conclusion Regarding the results of the study it can be concluded that the used obturation technique can indeed have an influence on the leakage behavior of a sealer and that this may also differ from sealer to sealer. The overall conclusion is that AH Plus is the densest material and that obturation combined with the lateral condensation or non-compaction technique is the method of choice.