Effect of adhesive hydrophilicity and curing time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin

Cadenaro, Milena; Breschi, Lorenzo; Rueggeberg, Frederick A.; Agee, Kelli; Di Lenarda, Roberto; Carrilho, Marcela; Tay, Franklin R.; Pashley, David H.

doi:10.1016/j.dental.2008.05.004

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Volume 25, Issue 1 , Pages 39-47, January 2009

Effect of adhesive hydrophilicity and curing time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin

Milena Cadenaro
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Italy
Lorenzo Breschi
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Italy
- IGM-CNR, Unit of Bologna c/o IOR, Bologna, Italy
Frederick A. Rueggeberg
- Division of Dental Materials Sciences, Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, Georgia, USA
Kelli Agee
- Department of Oral Biology, School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1129, USA
Roberto Di Lenarda
- Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Italy
Marcela Carrilho
- Department of Dental Materials and Oral Biochemistry, University of São Paulo, School of Dentistry, São Paulo, SP, Brazil
- Department of Restorative Dentistry - GEO, Bandeirante University of São Paulo, School of Dentistry, São Paulo, SP, Brazil
Franklin R. Tay
- Department of Oral Biology, School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1129, USA
David H. Pashley
- Department of Oral Biology, School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1129, USA
- Corresponding author. Tel.: +1 706 721 2033; fax: +1 706 721 6252.

Received 11 March 2008; received in revised form 28 April 2008; accepted 10 May 2008.

Abstract

Objective

This study examined the ability of five comonomer blends (R1–R5) of methacrylate-based experimental dental adhesives solvated with 10 mass% ethanol, at reducing the permeability of acid-etched dentin. The resins were light-cured for 20, 40 or 60s. The acid-etched dentin was saturated with water or 100% ethanol.

Method

Human unerupted third molars were converted into crown segments by removing the occlusal enamel and roots. The resulting crown segments were attached to plastic plates connected to a fluid-filled system for quantifying fluid flow across smear layer-covered dentin, acid-etched dentin and resin-bonded dentin. The degree of conversion of the resins was measured using Fourier transform infrared spectroscopy.

Result

Application of the most hydrophobic comonomer blend (R1) to water-saturated dentin produced the smallest reductions in dentin permeability (31.9, 44.1 and 61.1% after light-curing for 20, 40 or 60s, respectively). Application of the same blend to ethanol-saturated dentin reduced permeability of 74.1, 78.4 and 81.2%, respectively (p<0.05). Although more hydrophilic resins produced larger reductions in permeability, the same trend of significantly greater reductions in ethanol-saturated dentin over that of water-saturated dentin remained. This result can be explained by the higher solubility of resins in ethanol vs. water.

Significance

The largest reductions in permeability produced by resins were equivalent but not superior, to those produced by smear layers. Resin sealing of dentin remains a technique-sensitive step in bonding etch-and-rinse adhesives to dentin.

Keywords: Dentin permeability, Degree of conversion, Hydrophilic resins, Curing time, Ethanol-wet bonding