Computer-aided molecular design of water compatible visible light photosensitizers for dental adhesive

Abstract

Dental adhesive resin undergoes phase separation during its infiltration through the wet demineralized dentin and it has been observed previously that the hydrophilic-rich phase is a vulnerable region for failure due to the lack of photo-polymerization and crosslinking density. The lack of photo-polymerization is mostly due to the partitioning of photo-initiators in low concentrations within this phase. Here, a computational approach has been employed to design candidate water compatible visible light photosensitizers which could improve the photo-polymerization of the hydrophilic-rich phase. This study is an extension of our previous work. QSPRs were developed for properties related to the photo-polymerization reaction of the adhesive monomers and hydrophilicity of the photosensitizer using connectivity indices as descriptors. QSPRs and structural constraints were formulated into an optimization problem which was solved stochastically via Tabu Search. Four candidate photosensitizer molecules have been proposed here which have the iminium ion as a common feature.

No-waiting dentine self-etch concept—Merit or hype

“…Waxing and waning of the promises to deliver speedier, easier and more user-friendly adhesive versions precipitated a trough of disillusionment in adhesive dentistry. As more is known about the control of resin-dentine bond degradation via the use of the water-compatible catalytic systems [17], less hydrophilic adhesive resin monomers [16] and inhibition of adhesiveactivated endogenous proteases [16], clinicians begin to appreciate the benefits associated with step reduction for both the etch-and-rinse [7] and self-etch adhesives [18]. The simplified clinical manipulation and shortened application time associated with these new adhesive genres moved the industry to a slope of enlightenment.…”

Optimizing resin-dentin bond stability using a bioactive adhesive with concomitant antibacterial properties and anti-proteolytic activities

“…The curing properties of an adhesive system is one of the key factors for obtaining strong bonding to dentin [40]. The photoinitiator-amine system utilized for the experimental adhesive formulations is a relatively simple system that does not include ternary catalysts for buffering the acidity of resin monomers during the application of self-cured composites [41], or prevent phase separation of hydrophilic from hydrophobic resin components in the presence of water moisture [42]. It would be interesting to compare the degree of monomer conversion in experimental adhesives that contain different amounts of QAMS, and examine the effect of different initiator/accelerator systems on nanoscopical phase separation of resin components in future studies.…”

Water-associated attributes in the contemporary dentin bonding milieu

“…Depending on how the smear layer is treated with different etching modes, the magnitude of interstitial pulpal pressure (i.e. uninflamed vs inflamed pulps) [52], the hydrophilicity of the resinous components [47] as well as water compatibility of the photosensitizers [53], water-associated artifacts may be manifested as water-infused hybrid layers and adhesive layers [54], nanoscale phase separation into hydrophobic and hydrophilic resin-rich domains [55], water channels [56], bubbles [57] or discrete water films between the adhesive and resin composite [58]. Apart from rendering the polymerized resin matrix more susceptible to subsequent water ingress, these water-associated artifacts also increase interfacial permeability immediately after bonding [59].…”