Abstract
Tricalcium silicate-based cement are materials used in reparative and regenerative procedures in endodontics. A recently proposed formulation aimed to enhance handling during clinical use with a versatile material applicable by syringe. Although, the use of bismuth oxide as radiopacifier and grey raw powder are drawbacks considering aesthetics. Objectives Evaluate physicochemical, biological, and antimicrobial properties of Grey-MTAFlow (Ultradent) and assess whether the addition of zinc oxide (ZnO) prevents dentinal discoloration caused by bismuth oxide.Methodology Grey-MTAFlow was manipulated in 'thin' consistency for all tests. Luminosity, color change, ion migration to dentine, radiopacity, setting time, ISO 6876:2012 linear flow, volumetric lateral flow and central filling of simulated grooves scanned using micro-computed tomography (μCT), pH, calcium release, volumetric change using μCT, chemical characterisation, cytotoxicity, and antimicrobial activity were assessed. Addition of 5% ZnO to Grey-MTAFlow and a bismuth-containing experimental composition were comparatively tested. Statistical analyses used Shapiro-Wilk, T-test, ANOVA, and Kolmogorov-Smirnov (p<0.05).Results The addition of ZnO to Grey-MTAFlow prevented dentine darkening after 90 days due to bismuth migration reduction, although no statistical difference was found (p=0.863). ZnO addition significantly enhanced Grey-MTAFlow radiopacity without differences in initial setting time. Grey-MTAFlow presented an ISO linear flow of 10.9 mm and a balanced volumetric lateral flow with central filling in μCT evaluation. All compositions presented an alkaline pH after immersion. Grey-MTAFlow had a significantly higher calcium ion release after 28 days in comparison to 24 hours (p=0.011) and volumetric expansion of 0.4±1.8% after immersion. ZnO addition altered the hydrated cement matrix once calcium hydroxide (portlandite) could not be detected in characterisation. Neither of the materials produced inhibition halos nor reduced bacterial turbidity, but all presented cytocompatibility above 100%.Conclusion Grey-MTAFlow expanded after immersion and exhibited higher luminosity values after the evaluation period when ZnO was added, but chemical modifications after this addition occurred.
Highlights
One of the shortcomings with the use of mineral trioxide aggregate (MTA) is the susceptibility to tooth discoloration, which is caused by the interaction between the bismuth oxide contained in its formulation with dental hard structures3 and sodium hypochlorite used during root canal therapy
Tooth discoloration was evident in the buccal surface samples filled with Grey-MTAFlow (Figure 2a)
The addition of zinc oxide (ZnO) to Grey-MTAFlow resulted in a trend of increase in the luminosity after
Summary
Tricalcium silicate-based cement has been widely used for endodontic therapy since the 1990s, when mineral trioxide aggregate (MTA) was introduced.. Grey-MTAFlow cement (Ultradent Products Inc., South Jordan, UT, USA) containing tricalcium and dicalcium silicate and bismuth oxide has recently been introduced in the market. This material is available in powder and water-based gel and can be prepared at different consistencies, namely: thin, thick, and putty. No studies have yet evaluated its color stability This material is grey, and the presence of bismuth oxide in its composition is a factor that may cause discoloration after contact with the dentine.
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