Journal of Dental Research, Vol 78, 898-905, Copyright © 1999 by International & American Associations for Dental Research Online Journals

ARTICLES

Effects of dentin depth and cavity configuration on bond strength

T. Yoshikawa, H. Sano, M. F. Burrow, J. Tagami and D. H. Pashley
Department of Operative Dentistry, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.

During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that develops in cavities with high C-factors.

This article has been cited by other articles:

				J. H. Purk, M. Healy, V. Dusevich, A. Glaros, and J. D. Eick In vitro microtensile bond strength of four adhesives tested at the gingival and pulpal walls of Class II restorations. J Am Dent Assoc, October 1, 2006; 137(10): 1414 - 1418. [Abstract] [Full Text] [PDF]

				C. S. Costa Pfeifer, R. R. Braga, and P. E. C. Cardoso Influence of cavity dimensions, insertion technique and adhesive system on microleakage of Class V restorations J Am Dent Assoc, February 1, 2006; 137(2): 197 - 202. [Abstract] [Full Text] [PDF]

				H. Sano Microtensile Testing, Nanoleakage, and Biodegradation of Resin-Dentin Bonds J. Dent. Res., January 1, 2006; 85(1): 11 - 14. [Full Text] [PDF]

				R.R. Braga and J.L. Ferracane ALTERNATIVES IN POLYMERIZATION CONTRACTION STRESS MANAGEMENT Crit. Rev. Oral. Biol. Med., May 1, 2004; 15(3): 176 - 184. [Abstract] [Full Text] [PDF]

				J. H. PURK, V. DUSEVICH, A. GLAROS, P. SPENCER, and J. D. EICK In vivo versus in vitro microtensile bond strength of axial versus gingival cavity preparation walls in Class II resin-based composite restorations J Am Dent Assoc, February 1, 2004; 135(2): 185 - 193. [Abstract] [Full Text] [PDF]

				S. Bouillaguet BIOLOGICAL RISKS OF RESIN-BASED MATERIALS TO THE DENTIN-PULP COMPLEX Crit. Rev. Oral. Biol. Med., January 1, 2004; 15(1): 47 - 60. [Abstract] [Full Text] [PDF]

				S. DELIPERI and D. N. BARDWELL An alternative method to reduce polymerization shrinkage in direct posterior composite restorations J Am Dent Assoc, October 1, 2002; 133(10): 1387 - 1398. [Abstract] [Full Text] [PDF]