Elsevier

Dental Materials

Volume 37, Issue 11, November 2021, Pages 1676-1687
Dental Materials

Dry bonding to dentin: Broadening the moisture spectrum and increasing wettability of etch-and-rinse adhesives

https://doi.org/10.1016/j.dental.2021.08.021Get rights and content
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Abstract

Objective

To determine whether the effect of dentin moisture on the etch-and-rinse bonding may be minimized by dry-bonding protocols utilizing aqueous or ethanolic dimethyl sulfoxide (DMSO) pretreatments.

Methods

H3PO4-etched mid-coronal dentin surfaces from human molars were randomly blot- or air-dried for 30 s and pretreated with DMSO/H2O or DMSO/EtOH solutions. Untreated samples served as control. Moisture control was performed by either blot- or air-drying. Samples were bonded with a multistep etch-and-rinse adhesive. Restored crown segments (n = 8/group) were stored in distilled water for 24 h and sectioned for microtensile bond strength testing. Resin-dentin beams (0.8 mm2) were tested under tension until fracture (0.5 mm/min) after 24 h and two years of storage in artificial saliva at 37 °C.

SEM nanoleakage evaluation was performed on aged samples. Collagen wettability was also measured by sessile drops of the hydrophilic and hydrophobic bonding resins (n = 8/group). Data were examined by factorial ANOVA followed by the Tukey test (α = 0.05).

Results

Dry bonding to untreated collagen produced inferior immediate and long-term bond strengths than wet bonding (p < 0.05). Regardless of initial hydration and moisture control, DMSO-dry bonding produced initially higher and stable bond strengths after aging (p < 0.05). DMSO-pretreated groups presented improved collagen wettability with lower silver uptake (p < 0.05).

Significance

Despite the common belief that etch-and-rinse adhesives must be applied onto moist collagen, DMSO-dry bonding protocols not only improved bonding performance and hybrid layer integrity, but also brought more versatility to collagen hybridization by reducing overdrying-related issues.

Keywords

Bond strength
Dimethyl sulfoxide
DMSO
Wet bonding
Nanoleakage
Contact angle
Ethanol
HEMA
Collagen

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