Abstract
This study aimed to investigate the influence of immersion duration and the type of immersion solution on the outcome of push-out bond strength (POBS) tests. Root canals of 120 straight single-rooted teeth were instrumented to a diameter of 1.5 mm and irrigated with 5 mL of 3% NaOCl. Four horizontal slices with a thickness of 1 mm were cut, representing the mid-portion of the root. The specimens (n = 480) were irrigated with 17% ethylenediaminetetraacetic acid(EDTA) for 60 seconds, then twice with distilled water (DW) for 30 s each. The canals were filled with either AH Plus (Dentsply Sirona, Konstanz, Germany) or BioRoot RCS (Septodont, St. Maur-des-Fossés, France) (n = 240). Separated into four groups per type of sealer (n = 60), the specimens were incubated at 37 °C covered with gauze moistened in DW or phosphate-buffered saline (PBS) for either one or eight weeks. Dislodgement resistance was measured and POBS was calculated. Statistical analysis was performed using the analysis of variance (ANOVA) test and the Student–Newman–Keuls test (p = 0.05). AH Plus showed higher POBS when stored in PBS compared to DW, irrespective of the incubation period (p < 0.05). BioRoot RCS displayed higher POBS when stored in DW compared to PBS after eight weeks of incubation (p < 0.05). No difference was found after one week of incubation (p > 0.05). Irrespective of the sealer or the immersion solution, POBS decreased from one week to eight weeks (p < 0.05). Mixed failure modes were found in all groups irrespective of sealer, immersion medium, or immersion period. POBS decreased after a longer incubation time in both immersion solutions. Duration of immersion and the type of immersion solution had a significant impact on the outcome of the POBS testing protocol.
Highlights
Push-out bond strength (POBS) tests are well established in the laboratory assessment of characteristics of endodontic sealers [1], irrespective of the clinical applicability of the results [2].Innumerable protocols have been described in past literature, but so far, no protocol standardization has been achieved [2]
AH Plus showed higher POBS when stored in phosphate-buffered saline (PBS) compared to distilled water (DW), irrespective of the incubation period (p < 0.05)
The present study was designed to figure out the influence of PBS solution on the push-out bond strength of an epoxy resin and a calcium silicate-based sealer compared to DW after different periods of immersion
Summary
Push-out bond strength (POBS) tests are well established in the laboratory assessment of characteristics of endodontic sealers [1], irrespective of the clinical applicability of the results [2].Innumerable protocols have been described in past literature, but so far, no protocol standardization has been achieved [2]. According to their systematic review, POBS values were influenced by country and year of publication, use of human or bovine dentine, tooth portion, type of sealer, core material, obturation technique, and testing-machine velocity, as well as the duration of specimen storage [3] Variables such as the ratio of the plunger diameter and the specimen’s obturation diameter [1,4,5], different canal preparation protocols [2], the use of gutta-percha as a core material versus sealer as the sole obturation material [6], and the use of bovine or human dentine [7] have been reported in the literature as affecting the push-out model
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