Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

Abstract

ObjectiveSince their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set in dental cements. They may be capable of supporting repair and remineralization of dentin left after decay and cavity preparation, following the concepts of ion exchange from glass ionomers.MethodsThis paper reviews the underlying chemistry and interactions of glass ionomer and calcium silicate cements, with dental tissues, concentrating on dentin–restoration interface reactions. We additionally demonstrate a new optical technique, based around high resolution deep tissue, two-photon fluorescence and lifetime imaging, which allows monitoring of undisturbed cement–dentin interface samples behavior over time.ResultsThe local bioactivity of the calcium-silicate based materials has been shown to produce mineralization within the subjacent dentin substrate, extending deep within the tissues. This suggests that the local ion-rich alkaline environment may be more favorable to mineral repair and re-construction, compared with the acidic environs of comparable glass ionomer based materials.SignificanceThe advantages of this potential re-mineralization phenomenon for minimally invasive management of carious dentin are self-evident. There is a clear need to improve the bioactivity of restorative dental materials and these calcium silicate cement systems offer exciting possibilities in realizing this goal.

Polymer Nanocarriers for Dentin Adhesion

“…1h) and calcium crystal formations (Fig. 2c) probably correspond with calcium hydroxide and/or calcium carbonate compounds (HAp precursors) (Watson et al, 2014). Crystal formations were not detected in XRD analysis because of their small size and proportion with respect to the amorphous phase.…”

“…The presence of silicon may be important, since silicon is known to facilitate CaP deposition on particles (Leonor et al, 2009), and played a critical role in the binding of CaP to the collagen network (Besinis et al, 2014). Silica NPs have been shown to mediate the formation of CaP precursors, necessary for the subsequent steps of mineralization, acting as a nucleating mineral (Watson et al, 2014). Besinis et al (2014) applied silica and HAp nanoparticles to demineralized dentin and hypothesized that phosphorus binds to silica NPs, thus enhancing remineralization when combined with ionic calcium.…”

On modeling and nanoanalysis of caries-affected dentin surfaces restored with Zn-containing amalgam and in vitro oral function

“…Zn-containing amalgams enhanced the physical, mechanical and electrochemical properties of the restoration, and it also increases the heterogeneity and so, the fatigue resistance of the amalgam microstructure 19 . Zn-rich products at the toothamalgam interface, as ZnSn(OH) 6 , ZnO2, and Zn ++ free 20 , improved the sealing of the dentin-amalgam interface, enhancing the clinical lifetime of this restoration 21 . Previous outcomes have demonstrated that Zn-containing amalgams promoted an increase of nanomechanical properties, and a general augmentation of mineral gradients, ratios and crystallinity in partially mineral-depleted dentin surfaces.…”

“…Caries-affected dentin (CAD) is partially demineralized and more porous than noncarious dentin with a predominantly intact collagen matrix, whose collagen fibrils retain their banded structure and intermolecular crosslinks 4 . It should be preserved during clinical treatment because it is remineralizable and serves as a suitable substrate for tooth repair 5 and physiologic remineralization 6 .…”

Ex vivo detection and characterization of remineralized carious dentin, by nanoindentation and single point Raman spectroscopy, after amalgam restoration

“…Caries-affected dentin is partially demineralized and more porous than non-carious dentin with a predominantly intact collagen matrix, whose collagen fibrils retain their banded structure and intermolecular crosslinks [6] . It should be preserved during clinical treatment because it is remineralizable and serves as a suitable substrate for tooth repair [7] and physiologic or therapeutic remineralization [8] . By the time being, amalgam continues to play a major role in restorative dentistry, today [9] , though it is not an ideal material, as the cosmetic appearance is poor and cannot bond to tooth [10] .…”