Paula Dapper Santos

Influence of radiopaque fillers on physicochemical properties of a model epoxy resin-based root canal sealer

Objective To verify the influence of radiopaque fillers on an epoxy resin-based sealer. Material and Methods Experimental sealers were formulated by adding 20%, 40%, 60%, 80%, 100% and 120% of calcium tungstate, ytterbium trifluoride or barium sulphate by weight to an epoxy-resin-base. Setting time, flow, film thickness, radiopacity, sorption, solubility, pH and push-out bond strength were evaluated. Results The setting time ranged from 373 to 612.66 min, the flow varied from 13.81±0.49 to 22.49±0.37 mm, and the film thickness ranged from 16.67±5.77 to 33.33±11.54 µm. The lowest pH was 5.47±0.53, and the highest was 6.99±0.03. Radiopacity varied from 0.38±0.04 to 2.57±0.21 mmAl and increased with the amount of filler. Calcium tungstate sealers had a higher sorption and solubility than other sealers. There was no significant difference in the push-out bond strength among the fillers at the 120% concentration. Conclusion The inorganic fillers evaluated and their concentrations affect the physicochemical properties of an epoxy resin-based root canal sealer.

Synthesis and characterization of a glycerol salicylate resin for bioactive root canal sealers.

AIM To develop and characterize a salicylate resin with potential use in bioactive endodontic sealers. METHODOLOGY Methyl salicylate, glycerol and titanium isopropoxide were added in a closed system for the transesterification reaction. The resin obtained was characterized by proton nuclear magnetic resonance spectroscopy (1H NMR) and size exclusion chromatography (SEC). To verify the applicability of the resin to the development of endodontic sealers, experimental cements were prepared by mixing glycerol salicylate resin, calcium hydroxide and methyl salicylate in the ratios of 2 : 1 : 1, 1 : 2 : 1, 1 : 1 : 2, 1 : 1 : 1, 4 : 1 : 1, 1 : 4 : 1 and 1 : 1 : 4. Setting times were measured according to ISO 6876. Features of the hardening reaction were described by micro-RAMAN spectroscopy. RESULTS The transesterification reaction had a 72% efficiency. The (1) H NMR analysis revealed the presence of the expected functional groups (hydroxyls and aromatic rings), and the SEC confirmed the molar mass of the resin produced. The setting times of experimental sealers ranged from 70 min (ratio 1 : 1 : 1) to 490 min (ratio 1 : 1 : 4). The conversion of the salicylic groups (1 613 cm(-1) ) to salicylate salt (1 543 cm(-1) ) and the reduction in calcium hydroxide peaks (1084 and 682 cm(-1) ) were confirmed by micro-RAMAN spectroscopy, which showed the calcium chelation by the resin. CONCLUSION The new glycerol salicylate resin was successfully synthesized and revealed a potential application in the development of endodontic sealers.

Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement

The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cements ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59 ± 0.06 and 12.54 ± 0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

Methacrylate‐based root canal sealer containing chlorexidine and α‐tricalcium phosphate

The aim of this study was to develop and to characterize a methacrylate-based root canal sealer containing chlorhexidine (CHX) and α-tricalcium phosphate (α-TCP). Experimental dual cure methacrylate-based sealer was produced containing 0, 2.5, or 5 wt% of CHX and 0, 25, or 50 wt% of α-TCP. Experimental sealers were evaluated based on flow, film thickness, radiopacity, degree of conversion (DC), degradation in water, pH and antibacterial activity. Flow ranged from 15.09 ± 0.11 to 17.47 ± 0.42 mm. All groups presented mean film thickness lower than 50 µm and had radiopacity equivalent to 3 mmAl. DC was higher than 60% for all compositions. The weight loss (WL) ranged 0.12-3.47%. The groups containing 5% of CHX presented the highest WL and the lower pH values after 28 days of water immersion. All chlorexidine-compositions exhibited antibacterial efficacy against Enterococcus faecalis on direct contact and agar diffusion tests. CHX and α-TCP addition at an experimental methacrylate-based root canal sealer influenced the physicochemical properties and provided antibacterial properties. The incorporation of CHX and α-TCP could be an alternative to antibacterial sealers with potential to improve periapical healing in endodontic treatments.