Physicochemical Properties, Cytocompatibility and Antibiofilm Activity of a New Calcium Silicate Sealer

Biological properties versus solubility of endodontic sealers and cements

Endodontic sealers and cements used in root canal treatment have different compositions and properties. Common to all materials is that their primary goal is to fill gaps and voids, making a permanent seal of the root canal system. Furthermore, aspects such as antibacterial properties, cytotoxicity, setting time, solubility and biocompatibility are also crucial and ought to be considered. Over the years, a shift in the view on the importance of these aspects has ocurred. Whereas the antibacterial properties were considered important when the technical factors in endodontics were less developed, the sealing ability and biocompatibility have later been considered the most critical factors. The introduction of tricalcium silicate cements and sealers has led to a renewed interest in material properties, as these cements seem to have good sealing ability and at the same time combine favourable antimicrobial effects with excellent biocompatibility. This review discusses how the various properties of root canal sealers and cements may conflict with the primary aim of providing a permanent seal of the root canal system.

Biocompatibility and bioactive potential of NeoPUTTY calcium silicate-based cement: An in vivo study in rats

AIM

To evaluate the inflammatory reaction and the ability to induce mineralization activity of a new repair material, NeoPUTTY (NPutty; NuSmile, USA), in comparison with Bio-C Repair (BC; Angelus, Brazil) and MTA Repair HP (MTA HP; Angelus, Brazil).

METHODOLOGY

Polyethylene tubes were filled with materials or kept empty (control group, CG) and implanted in subcutaneous tissue of rats for 7, 15, 30, and 60 days (n = 6/group). Capsule thickness, number of inflammatory cells (ICs), fibroblasts, collagen content, and von Kossa analysis were performed. Unstained sections were evaluated under polarized light and by immunohistochemistry for osteocalcin (OCN). Data were submitted to two-way anova followed by Tukey's test (p ≤ .05), except for OCN. OCN data were submitted to Kruskal-Wallis and Dunn and Friedman post hoc tests followed by the Nemenyi test at a significance level of 5%.

RESULTS

At 7, 15, and 30 days, thick capsules containing numerous ICs were seen around the materials. At 60 days, a moderate inflammatory reaction was observed for NPutty, BC while MTA HP presented thin capsules with moderate inflammatory cells. In all periods, NPutty specimens contained the highest values of ICs (p < .05). From 7 to 60 days, the number of ICs reduced significantly while an increase in the number of fibroblasts and birefringent collagen content was observed. At 7 and 15 days, no significant difference was observed in the immunoexpression of OCN (p > .05). At 30 and 60 days, NPutty showed the lowest values of OCN (p < .05). At 60 days, a similar immunoexpression was observed for BC and MTA HP (p > .05). In all time intervals, capsules around NPutty, BC, and MTA HP showed von Kossa-positive and birefringent structures.

CONCLUSIONS

Despite the greater inflammatory reaction promoted by NeoPutty than BC and MTA HP, the reduction in the thickness of capsules, the increase in the number of fibroblasts, and the reduction in the number of ICs indicate that this bioceramic material is biocompatible Furthermore, NeoPutty presents the ability to induce mineralization activity.

Premixed calcium silicate-based root canal sealers have better biological properties than AH Plus: A systematic review and meta-analysis of in vivo animal studies and in vitro laboratory studies

Objectives

The aim was to determine whether premixed calcium silicate-based root canal sealers have better biological properties than AH Plus.

Materials and Methods

Searches of studies published up to January 2023 were performed in the PubMed/MEDLINE and EMBASE and via other methods (databases of the International Endodontic Journal, Journal of Endodontics, and gray literature). The inclusion criteria were in vivo animal and in vitro studies that analyzed the response in the dorsal subcutaneous tissue of rats, cell viability, and genotoxicity. Systematic Review Centre for Laboratory Animal Experimentation Risk of Bias (RoB) tool for in vivo studies and modified CONSORT checklist for in vitro were appraised. Meta-analysis was performed using the Stata.

Results

Fifty-two studies were included. In the RoB, in vivo studies fulfilled 20%-50% of the items and in vitro 60%-100%. The studies included in the meta-analysis demonstrated better histocompatibility with the premixed calcium silicate-based sealers at 30 days and greater cell viability with these sealers when used in undiluted extracts in experimental period of 72 h and in extracts with 1:2 and 1:4 dilution in 24 and 72 h. In contrast, no difference between materials was found concerning genotoxicity.

Conclusion

Premixed calcium silicate-based root canal sealers have better histocompatibility and are less cytotoxic than the epoxy resin-based sealer AH Plus, demonstrating favorable biological behavior.

Bioactive potential of Bio-C Temp demonstrated by systemic mineralization markers and immunoexpression of bone proteins in the rat connective tissue

Intracanal medications are used in endodontic treatment due to their antibacterial activity and ability to induce the periapical repair. Among the intracanal medications, the Calen (CAL; SS. White, Brazil) is a calcium hydroxide-based medication that provides an alkaline pH and releases calcium, exerting an antimicrobial activity. Bio-C Temp (BIO; Angelus, Brazil), a ready-to-use bioceramic intracanal medication, was designed to stimulate the mineralized tissues formation. Here, we investigated the bioactive potential of BIO in comparison to the CAL in the rat subcutaneous. Polyethylene tubes filled with medications, and empty tubes (control group, CG) were implanted in the subcutaneous tissue of rats. After 7, 15, 30 and 60 days, the blood was collected for calcium (Ca+2) and alkaline phosphatase (ALP) measurement, and the capsules around the implants were processed for morphological analyses. The data were submitted to two-way ANOVA and Tukey test (p < 0.05). At 7, 15 and 30 days, the ALP level was grater in BIO and CAL than in CG (p < 0.0001). At 7 and 15 days, greater Ca+2 level was seen in the serum of CAL samples. From 7 to 60 days, an increase in the number of fibroblasts, osteocalcin- and osteopontin-immunolabelled cells was observed in BIO and CAL groups (p < 0.0001). In all periods, BIO and CAL specimens showed von Kossa-positive structures. Moreover, ultrastructural analysis revealed globules of mineralization in the capsules around the BIO and CAL specimens. Thus Bio-C Temp caused an increase in the ALP, osteocalcin and osteopontin, which may have allowed the formation of calcite, suggesting bioactive potential.

Comparison of physico-chemical properties of zinc oxide eugenol cement and a bioceramic sealer

The aim of the present study was to compare the physico-chemical properties of EssenSeal with AH PLUS bioceramic and Pulp Canal Sealer EWT. Flow, solubility, film thickness, radiopacity and setting time were evaluated according to ISO 6876 (2012) specifications. External and cross-section surface characteristics were analysed under a scanning electron microscope. Statistical analysis was performed using Shapiro-Wilk's test, one-way ANOVA and the Tukey HSD test. All the sealers conformed to the ISO 6876 (2012) standards, except for the setting time for AH plus bioceramic, which exceeded more than 10% of the time indicated by the manufacturer. Statistically significant differences were found between the three study sealers regarding the physico-chemical properties tested (p < 0.05). EssenSeal demonstrated characteristics respecting the ISO 6876 (2012) standards and can be considered a predictable alternative in root canal sealing.

The Washout Resistance of Bioactive Root-End Filling Materials

Fast-setting bioactive cements were developed for the convenience of retrograde fillings during endodontic microsurgery. This in vitro study aimed to investigate the effect of irrigation on the washout of relatively fast-setting materials (Biodentine, EndoCem Zr, and MTA HP) in comparison with MTA Angelus White and IRM in an apicectomy model. Washout resistance was assessed using artificial root ends. A total of 150 samples (30 for each material) were tested. All samples were photographed using a microscope, and half of them were also scanned. The samples were irrigated and immersed in saline for 15 min. Then the models were evaluated. Rinsing and immersing the samples immediately after root-end filling and after 3 min did not disintegrate the fillings made of all tested materials except Biodentine. Root-end fillings made of Biodentine suffered significant damage both when rinsing was performed immediately and 3 min after the filling. Quantitative assessment of washed material resulted in a slight loss of IRM, EndoCem MTA Zr, and MTA HP. MTA Angelus White showed a slightly greater washout. Rinsing and immersion of Biodentine restorations resulted in their significant destruction. Under the conditions of the current study, the evaluated materials, excluding Biodentine, showed good or relatively good washout resistance.

Mechanism of action of Bioactive Endodontic Materials

A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.