Light-Embrittled Dental Resin Cements Containing Photodegradable Polyrotaxane Cross-Linkers for Attenuating Debonding Strength

Abstract

Notwithstanding the progress of dental material adhesion on tooth surfaces in the past several decades, debonding strongly adhered restorative materials from tooth surfaces remains a challenging issue. Herein, we propose the use of photodegradable polyrotaxanes (PRXs), which are supramolecular-interlocked polymers comprising α-cyclodextrin threaded along a poly­(ethylene glycol) (PEG) axle, as a component of adhesive resin cements to attenuate debonding strength via light irradiation. We synthesized photodegradable PRXs (iNB-PRXs) using internally o-nitrobenzyl ester-introduced PEG as an axle polymer. Notably, approximately 60% of iNB-PRX degraded into its constituent molecules after 5 min of irradiation with ultraviolet (UV) light. Thereafter, iNB-PRX was combined with the clinically utilized adhesive resin cement, and a poly­(methyl methacrylate) (PMMA) block was adhered on the surface of bovine dentin using an adhesive resin cement cross-linked with iNB-PRX. Although the PMMA block was successfully adhered onto the dentin with a clinically acceptable adhesive force, the tensile strength of the PMMA–dentin specimens decreased significantly upon UV irradiation for 2 min owing to the UV-induced degradation of the iNB-PRX cross-linker. According to these results, the adhesive resin cement containing photodegradable iNB-PRX cross-linkers is a promising candidate for facilitating the debonding of dental materials from tooth surfaces via UV light irradiation.

Stimuli-responsive temporary adhesives: enabling debonding on demand through strategic molecular design

“…The development and adaptation of adhesive materials, particularly stimuli-responsive temporary adhesives, has signicantly contributed to the advancement of human civilization and economic growth. 1,2 From the Paleolithic use of tarlike substances for tool manufacturing to modern adhesive applications in medicine, [3][4][5][6][7] electronics, [8][9][10][11] construction, 12 and consumer products, 13 adhesives permeate much of our daily life. 14 For example, over 50 billion Post-It notes-those ubiquitous brightly-colored notes that stick to surfaces, but are easily removed and rearranged-are sold each year worldwide.…”

“…19 For example, this type of adhesive is extremely promising for biomedical applications, where fragile surfaces, such as organs or healing wounds, must be protected during removal. [20][21][22][23] In contrast, stimuli-responsive materials that demonstrate permanent adhesion aer a stimulating event are especially useful in dentistry, 6,7 wound dressings, 5,23,24 and aerospace engineering. 25,26 Unique characteristics of stimuli-responsive temporary adhesives A stimuli-responsive adhesive is a material designed to promote the joining of two surfaces that exhibits a change in its mechanical and/or adhesive properties aer being exposed to an external stimulus or stimuli.…”

“…19 For example, this type of adhesive is extremely promising for biomedical applications, where fragile surfaces, such as organs or healing wounds, must be protected during removal. 20–23 In contrast, stimuli-responsive materials that demonstrate permanent adhesion after a stimulating event are especially useful in dentistry, 6,7 wound dressings, 5,23,24 and aerospace engineering. 25,26…”

Weakly acidic carboxy group-grafted β-cyclodextrin-threaded acid-degradable polyrotaxanes for modulating protein interaction and cellular internalization

“…Another advantage of PRXs for material applications is their stimuli-responsive dissociative character [5,6]. When stimuli-cleavable chemical bonds are introduced in the axle polymer, the resulting PRXs readily dissociate into their constituent molecules in response to various chemical and physical stimuli, such as pH, light, reductive molecules, and reactive oxygen species (ROS) [7][8][9][10]. These stimuli-degradable PRXs have been applied as delivery carriers of drugs, therapeutic genes, and proteins for achieving immediate release of therapeutic cargos through the stimuli-induced degradation of the PRXs in intracellular environments (e.g., acidic pH and reductive glutathione) [9][10][11][12][13][14][15].…”

Thin‐layer photodegradable polyrotaxane gel‐immobilized surfaces for photoregulation of surface properties and cell adhesiveness

“…Interestingly, such stimuli‐induced degradation of PRXs can be triggered by cleaving only one site of the cleavable bond. Based on this approach, we have developed various stimuli‐degradable PRXs that can degrade in response to pH, light, reductive molecules, and enzymatic reactions, and investigated their applications in biomaterials and drug delivery systems 24–28 . In particular, we previously developed UV and visible light‐degradable PRX organogels by crosslinking photodegradable PRXs capped with methyltrithiocarbonate‐ S ‐phenylacetic acid (MTP) as a photolabile bulky stopper molecule (Figure 1).…”