Einfluss verschiedener medikamentöser Einlagen auf den Haftverbund vonAH Plus zum Wurzelkanaldentin

The bonding between the root canal dentin and the root canal filling is an essential key for a successful endodontic treatment. The aim of the study was to investigate to which extent the usage of medicaments on the basis of different agents (calciumhydroxide or chlorhexidine digluconate) and different dosage forms (gel/paste or point) impacts the bonding between the sealer AH Plus and the root canal dentin. 60 human teeth, each with straight roots and one root canal were mechanically treated to a size of ISO 60 with the BioRaCe-System. The teeth were shortened to a final root canal length of 8 mm and randomly allocated to six groups (n = 10). Each group received different medicamentous fillings and were marked as follows: (A) = Chlorhexamed DIREKT Gel, 1 %; (B) = UltraCal XS Paste, 35 %; (C) = ROEKO Activ Point chlorhexidine points, 5 %; (D) = ROEKO Calciumhydroxide Plus points, 52 %; (E) = control group moist root canal without medicament; (F) = control group dry root canal without medicament. After a storage time of two weeks at 100 % air moisture and room temperature, the medicaments were removed by irrigation of the root canal system with 2.5 ml of distilled water. The teeth were prepared for the pull-out test by adding retention grooves with a separating disk and submerging them in dental acrylic. After cooling of the dental acrylic every probe was subjected to a precisely irrigation protocol: step 1: 2.5 ml sodium hypochlorite (NaOCl), 3 %, 1 min ultrasonic activation via EndoActivator; step 2: 2.5 ml ethylenediaminetetraacetic acid (EDTA), 16 %, 1 min ultrasonic activation via EndoActivator; step 3: 2.5 ml NaOCl; step 4: 2.5 ml distilled water. Spreader blanks of size ISO 55 were adjusted to the command variable of ISO 60 by apical reduction, burred and polished, but not silicated. The sealer AH Plus was delivered into the root canals by delivery cannulas and the adapted spreaders were inserted. The probes were stored two weeks for hardening, whereupon the pull-out test by Ebert et al. (2011) followed [29]. A Zwick universal testing machine and for statistic analysis the software SPSS 21 were used. The received data were analysed using the Kruskal-Wallis test and the Mann-Whitney-Test. The level of significance was set at p ≤ 0.05. In order to make a statement about the failure mode, each spreader was digitally photographed, whereupon these pictures were analyzed in this regard. The resulting bond strength values in descending order under specification of the median value were summarized as follows: (C) Activ Point chlorhexidine points (3.52 MPa), (B) UltraCal XS Paste (2.63 MPa), (A) Chlorhexamed DIREKT Gel (1.63 MPa), (F) dry control group (1.43 MPa), (E) moist control group (1.32 MPa), (D) Calciumhydroxide Plus points (1.20 MPa). 90 % revealed a mixed failure mode. Therefore after 14 days, AH Plus showed clearly higher bond strength values after placement of Activ Points compared with the control groups without medicaments, irrespective of dry or moist root canals. The use of UltraCal XS Paste could slightly improve the bonding values, too. The other medical dressings showed just slightly better or even lower bond strength values than the control groups. In spite of this clear trend of improving bond strength by insertion of chlorhexidine points, there haven’t been any significant differences between the experimental groups (Kruskal-Wallis test: p = 0.482). Root canal medicaments on the basis of calciumhydroxide and chlorhexidine digluconate had different effects on the bond strength between the sealer AH Plus and the root canal dentin. Chlorhexidine digluconate as a point resulted in an increased bond strength, compared to the control groups. Consequently, Activ Points were able to improve the bonding between the sealer and the root canal dentin. Calciumhydroxide as a paste showed slightly better results than the dry control group. The other medical dressings caused comparable bond values or tend to result in lower ones, too. The failure modes confirm a strong and reliable bonding between sealer and root canal dentin.