Durability of Resin-Dentin Bonds to Water- vs. Ethanol-saturated Dentin

Abstract

Higher 24-hour resin-dentin bond strengths are created when ethanol is used to replace water during wet bonding. This in vitro study examined if ethanol-wet-bonding can increase the durability of resin-dentin bonds over longer times. Five increasingly hydrophilic experimental resin blends were bonded to acid-etched dentin saturated with water or ethanol. Following composite build-ups, the teeth were reduced into beams for 24-hour microtensile bond strength evaluation, and for water-aging at 37°C for 3, 6, or 12 months before additional bond strength measurements. Although most bonds made to water-saturated dentin did not change over time, those made to ethanol-saturated dentin exhibited higher bond strengths, and none of them fell over time. Decreased collagen fibrillar diameter and increased interfibrillar spacing were seen in hybrid layers created with ethanol-wet-bonding. Increases in bond strength and durability in ethanol-wet-bonding may be due to higher resin uptake and better resin sealing of the collagen matrix, thereby minimizing endogenous collagenolytic activities.KEY WORDs: dentin bonding, durability, hydrophilicity, ethanol.

Bonding efficiency and durability: current possibilities

“…40,46,209 The "ethanol wet bonding" technique consists of gradually replacing water from interfibrillar and intrafibrillar spaces by ethanol, starting with the application of lower concentrations of ethanol solutions and slowly progressing to higher concentrations up to a complete dehydration of the exposed collagen network. 13,210,211,212 . Ethanol has a higher vapor pressure than water, enhancing its evaporation and creating wider interfibrilar spaces for impregnation of hydrophobic monomers to form a more stable hybrid layer.…”

“…216 This technique also prevents phase separation of hydrophobic resin monomers in the presence of water, 217,218,219 since the latter is completely replaced by ethanol prior to the application of the ethanolsoluble monomers. 220,221 Additionally, the elimination of residual water seems to contribute to decrease or even eliminate hydrolytic enzymatic degradation of collagen fibrils, 212,222 thereby increasing bond durability and stability. 213 However, this technique is very sensitive, time consuming and requires the application of many steps to achieve the desired dehydration, which becomes inappropriate.…”

One-Year Evaluation of a Simplified Ethanol-Wet Bonding Technique: A Randomized Clinical Trial

“…Therefore, it was necessary to adapt this technique to clinical conditions. Different dentin saturation times are described in the literature for EWBT, varying from 20 s to 3.5 min, and the concentration of the ethanol solutions can be gradually increased or applied in a single step (5)(6)(7)18). Tay et al (5) did not observe differences in bond strength between EWBT using one application of 100% ethanol and conventional etch-and-rinse strategy.…”

“…Presence of hydrophilic monomers and incomplete resin infiltration in demineralized dentin by etch-and-rinse technique may increase water sorption and risk of hydrolytic degradation, which may reduce the adhesive mechanical properties over time (1,(6)(7)(8)(9).…”

“…This hybrid layer is less hydrophilic and more resistant to overtime hydrolytic degradation caused by the endogenous enzymes, such as metalloproteinases (MMPs), due to a more effective collagen protection (19,20) and prevention of phase separation (8,18,21,22). Some laboratory studies demonstrated higher adhesive interface bond strengths when ethanol solutions were used to dehydrate dentin prior to primer and adhesive application, compared with the strengths achieved using conventional adhesive techniques (4,7,18,21). However, there is lack of clinical data for this strategy.…”