Design of a new dental adhesive-Effect of a water-soluble sodium acylphosphine oxide with crown ether on adhesion to dental hard tissues

Abstract

Thebehaviorofwater-solublephotoinitiatorswithcrownethersindentaladhesivesisunknown.Thisstudyinvestigatedthe effectofsodiumacylphosphineoxide(APO-Na)withcrownetherinahydrophobicadhesiveonadhesiontoteeth.Sodium 2,4,6-trimethylbenzoyl-phenylphosphine oxide (TMPO-Na = APO-Na) was synthesized in 67.1% yield and identified by 1 H NMR. APO-Na was dissolved in hydrophobic resins in the presence of a crown ether (ionophore effect). Thirty kinds of experimentalsingle-stepadhesivescomprisingAPO-Na,CE,Bis-GMA,6-methacryloyloxyhexylphosphonoacetate(6-MHPA), and4-methacryloyloxyethyltrimelliticacid(4-MET)weretherebyprepared.Shearbondstrengthtounetchedgroundteeth wasmeasuredatacrossheadspeedof1.0mm/min,andthedatawereanalyzedbyANOVA.Theshearbondstrengthresults of bonding resins containing APO-Na with 18-crown-6-ether (CE-6) were significantly higher than that without CE-6 (control) (p<0.05).Higherbondstrengthvalues[forenamel:BR24at19.3(3.2)MPa;fordentin:BR29at20.2(4.7)MPa]wereachieved with the adhesives containing APO-Na, CE-6, 6-MHPA, and 4-MET. Therefore, it was found that APO-Na with CE-6 contributed to the efficient bonding performance of single-step adhesive to teeth. However, in view of the biosafety hazard posedbycrownethers,thesearchisstillonforreagentsthatarebiologicallysaferthancrownethers-butwithionophor effects-tobeusedindentaladhesives.

A review of the development of radical photopolymerization initiators used for designing light-curing dental adhesives and resin composites

“…16 Structural formulas of the materials employed in the study 18) by Ikemura et al Full names of TMPO-Na (=APO-Na), TMDPO (=APO), 6-MHPA, TEGDMA, 4-MET, and Bis-GMA are given in Table 1. Resin A) and without (right: Resin B) 18-crown-6 19) . It is apparent that APO-Na powder was dissolved in hydrophobic Bis-GMA/TEGDMA resin in the presence of crown ether to form a clear liquid (Resin A).…”

“…To dissolve APONa as a sodium salt in hydrophobic water-free resins, crown ethers known as clathrate or inclusion compounds were considered. Figure 16 shows the structural formulas of the materials used in the study 19) . Fig.…”

“…The behavior of water-soluble photoinitiators with crown ethers in dental adhesives was an unknown. Our recent study 19) thus aimed to investigate the effect of APO-Na with crown ether in a hydrophobic adhesive on adhesion to teeth.…”

“…In our research study, the focus was shifted to a water-soluble photoinitiator, sodium acylphosphine oxide (APO-Na), in water-free hydrophobic adhesives 19) . The behavior of water-soluble photoinitiators with crown ethers in dental adhesives was an unknown.…”

“…Effects of Review water-soluble QTX in self-etching all-in-one adhesives on adhesion to polished dentin have been well investigated by Hayakawa et al [11][12][13][14][15][16] and Kikutake et al 17,18) and shown to be effective in improving the bond strength of composite resins to tooth substrates. In light of these encouraging results, a single-step hydrophobic adhesive which contained a water-soluble photoinitiator -sodium acylphosphine oxide (APONa)-and crown ether was synthesized, and its effect on adhesion to ground teeth was investigated 19) . Further, to design a single-step self-etching adhesive, our recent study 20) was carried out to investigate the effect of a single-step, self-etching, HEMA-free adhesive -which contained a phosphonic acid monomer and a carboxylic acid monomer-on adhesion without the use of water-soluble photoinitiators.…”