Methodological proposal for evaluation of adhesion of root canal sealers to gutta-percha

Functionalization of gutta-percha surfaces with argon and oxygen plasma treatments to enhance adhesiveness

Gutta-percha's lack of adhesion has been presented as a drawback to avoid gaps at sealer/gutta-percha interface. Plasma treatments have been scarcely assessed on gutta-percha surfaces as a method of enhancing adhesiveness. This study aimed to evaluate the effect of low-pressure Argon and Oxygen plasma atmospheres on conventional and bioceramic gutta-percha standardized smooth discs, assessing their roughness, surface free energy, chemical structure, and sealer wettability. A Low-Pressure Plasma Cleaner by Diener Electronic (Zepto Model) was used. Different gases (Argon or Oxygen), powers (25 W, or 50 W), and exposure times (30 s, 60 s, 120 s, or 180 s) were tested in control and experimental groups. Kruskal-Wallis and Student's t-test were used in data analysis. Statistically significant differences were detected when P < 0.05. Both gases showed different behaviors according to the parameters selected. Even though chemical changes were detected, the basic molecular structure was maintained. Argon or Oxygen plasma treatments favoured the wetting of conventional and bioceramic gutta-perchas by Endoresin and AH Plus Bioceramic sealers (P < 0.001). Overall, the functionalization of gutta-percha surfaces with Argon or Oxygen plasma treatments can increase roughness, surface free energy and wettability, which might improve its adhesive properties when compared to non-treated gutta-percha.

Evaluation of Bond Strength of Four Different Root Canal Sealers

The purposes of the study were to evaluate the influence of the sealer’s chemical composition on the interfacial strength between root canal dentin and root filling material, for two different classes of endodontic sealers, and to assess their failure modes. Methods: Forty extracted single-rooted teeth were randomly divided into four groups using the following endodontic sealers: RealSeal SE and Resilon (RSSE); EndoSequence BC sealer and BC Point (EBCS); Endoseal MTA and gutta-percha (EDS); Bioroot RCS and gutta-percha (BRS). Teeth were embedded in acrylic resin, and the roots were sectioned horizontally into 1 mm slices. For each slice, the perimeter was measured. A push-out test was performed using an Instron universal testing machine. For each sample, bond strength was calculated. Specimens were examined by SEM investigation in order to analyze the dentin−sealer−core interface. Results were assessed using analysis of variance (ANOVA) and Tukey and Bonferroni test. Results: Statistical analysis revealed that EDS and gutta-percha had significantly higher resistance to dislodgement compared to the other three groups (p < 0.05). EBCS and BC Point showed significantly greater push-out bond strength values compared to RSSE and Resilon (p < 0.05). Conclusions: Bioceramic endodontic sealers showed a higher bond strength to root dentin than methacrylate resin-based endodontic sealer.

Calcium Silicate-Based Root Canal Sealers: A Narrative Review and Clinical Perspectives

Over the last two decades, calcium silicate-based materials have grown in popularity. As root canal sealers, these formulations have been extensively investigated and compared with conventional sealers, such as zinc oxide-eugenol and epoxy resin-based sealers, in in vitro studies that showed their promising properties, especially their biocompatibility, antimicrobial properties, and certain bioactivity. However, the consequence of their higher solubility is a matter of debate and still needs to be clarified, because it may affect their long-term sealing ability. Unlike conventional sealers, those sealers are hydraulic, and their setting is conditioned by the presence of humidity. Current evidence reveals that the properties of calcium silicate-based sealers vary depending on their formulation. To date, only a few short-term investigations addressed the clinical outcome of calcium silicate-based root canal sealers. Their use has been showed to be mainly based on practitioners' clinical habits rather than manufacturers' recommendations or available evidence. However, their particular behavior implies modifications of the clinical protocol used for conventional sealers. This narrative review aimed to discuss the properties of calcium silicate-based sealers and their clinical implications, and to propose rational indications for these sealers based on the current knowledge.