EDTA or H3PO4/NaOCl dentine treatments may increase hybrid layers’ resistance to degradation: A microtensile bond strength and confocal-micropermeability study

Sauro, Salvatore; Mannocci, Francesco; Toledano, Manuel; Osorio, Raquel; Pashley, David H.; Watson, Timothy F.

doi:10.1016/j.jdent.2008.12.002

« Previous Next »Journal of Dentistry
Volume 37, Issue 4 , Pages 279-288, April 2009

EDTA or H₃PO₄/NaOCl dentine treatments may increase hybrid layers’ resistance to degradation: A microtensile bond strength and confocal-micropermeability study

Salvatore Sauro
- Dental Biomaterials Science, Biomimetics & Biophotonics, King's College London Dental Institute at Guy's, King's College and St Thomas's Hospitals, Floor 17 Guy's Hospital, London SE1 9RT, UK
- Corresponding author. Tel.: +44 207 188 3874; fax: +44 207 188 1823.
Francesco Mannocci
- Dental Biomaterials Science, Biomimetics & Biophotonics, King's College London Dental Institute at Guy's, King's College and St Thomas's Hospitals, Floor 17 Guy's Hospital, London SE1 9RT, UK
Manuel Toledano
- Department of Dental Materials, School of Dentistry, University of Granada, Colegio Maximo, Campus de Cartuja, Granada, Spain
Raquel Osorio
- Department of Dental Materials, School of Dentistry, University of Granada, Colegio Maximo, Campus de Cartuja, Granada, Spain
David H. Pashley
- Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, GA, USA
Timothy F. Watson
- Dental Biomaterials Science, Biomimetics & Biophotonics, King's College London Dental Institute at Guy's, King's College and St Thomas's Hospitals, Floor 17 Guy's Hospital, London SE1 9RT, UK

Received 9 September 2008; received in revised form 3 December 2008; accepted 9 December 2008.

Abstract

Objectives

The aim of this study was to reduce hybrid layer degradation created with simplified dentine adhesives by using two different methods to condition the dentine surface.

Methods

A smear-layer was created on flat dentine surfaces from extracted human third molars with a 180-grit/SiC-paper. Dentine specimens were conditioned before bonding with the following procedures: 37% H₃PO₄; H₃PO₄/0.5% NaOCl; 0.1M EDTA; 0.1M EDTA/0.5% NaOCl. Two etch-and-rinse adhesives: (Scotchbond 1XT or Optibond Solo Plus) were applied and light-cured. Composite build-ups were constructed. The bonded teeth were sectioned into beams, stored in distilled water (24h) or 12% NaOCl solution (90min) and finally tested for microtensile bond strengths (μTBS). Additional dentine surfaces were conditioned and bonded as previously described. They were prepared for a pulpal-micropermeability confocal microscopy study and finally observed using confocal microscopy.

Results

μTBS results revealed that both adhesives gave high bond strengths to acid-etched dentine before, but not after a 12% NaOCl challenge. Bonds made to acid-etched or EDTA-treated dentine plus dilute NaOCl, gave high μTBS that resisted 12% NaOCl treatment, as did EDTA-treated dentine alone. A confocal micropermeability investigation showed very high micropermeability within interfaces of the H₃PO₄, etched specimens. The lowest micropermeability was observed in H₃PO₄+0.5% NaOCl and 0.1M EDTA groups.

Conclusions

The use of dilute NaOCl (0.5%) after acid-etching, or the conditioning of dentine smear layers with 0.1M EDTA (pH 7.4) produced less porous resin–dentine interfaces. These dentine-conditioning procedures improve the resistance of the resin–dentine bond sites to chemical degradation (12% NaOCl) and may result in more durable resin–dentine bonds.

Keywords: Hybrid layer, Adhesion, Chemical degradation, Etch-and-rinse dental adhesive, NaOCl, EDTA