Dental discoloration caused by Grey-MTAFlow cement: analysis of its physicochemical, biological and antimicrobial properties

Abstract

Dental discoloration caused by Grey-MTAFlow cement: analysis of its physicochemical, biological and antimicrobial properties 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 bismuthcontaining 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.

Antimicrobial Activity of Calcium Silicate-Based Dental Materials: A Literature Review

“…Testing soluble materials-such as reparative endodontic materials-over agar plates seems inappropriate once solubility halos are observed, indicating possible misleading interpretations [34]. Previous studies reported similar observations when testing hydraulic endodontic materials in contact with agar [67,68,75], reporting a limited antimicrobial effect of the reparative endodontic tested materials (Figure 2-Adapted from cited reference [74]); other studies using other methods such as confocal microscopy in contact with dentin and a mature biofilm [84] also concluded that previous disinfection of the site to be treated with these materials is crucial and mandatory in order to expect a positive clinical outcome. Different storage methods for antimicrobial testing can also obtain varying results; in water, for example, ProRoot MTA showed higher antimicrobial activity than when aged in blood and exhibited significant antimicrobial activity reduction after 7 days [35].…”

“…The antimicrobial potential of reparative endodontic materials is directly related to their surface of contact, potential alkaline pH, and hydroxyl release [75], as these factors are directly responsible for damage to lipids, proteins, and DNA in the cell membranes of microorganisms [76]. Another antimicrobial mechanism of these materials is the presence of calcium in their composition, which reduces the presence of carbon dioxide in tissues, a molecule which is used by anaerobic bacteria, in addition to their alkaline pH, caused by the hydroxyl ions, which potentially also favors tissue repair [77].…”

Investigation of a modified hydraulic calcium silicate-based material – Bio-C Pulpo

“…The absence of a specific ISO standard for hydraulic calcium silicate-based materials warrants the inclusion of previously reported methods in the general selection of tests, and the use of the ISO 6876:2012 standard (for endodontic sealers) to evaluate new compositions 7,9,11,12,18,25,26,27 such as Bio-C Pulpo. The inclusion of MTT cell culture testing with fibroblasts was used as a preliminary test for subcutaneous animal biocompatibility, considering the principles of the 3Rs (Replacement, Reduction, and Refinement) in research.…”

Complicated Crown Fracture of Permanent Incisors: A Conservative Treatment Case Report and a Narrative Review

“…One of the major aesthetic complications after pulpotomy with white and grey MTA can be the discoloration of the tooth [ 36 , 37 ]. It is caused mainly by the oxidation of heavy metal oxides (bismuth or iron), and by the interaction between erythrocytes and the unset cement in case of inadequate hemostasis [ 38 , 39 , 40 ].…”