Effect of dentin surface roughness on shear bond strength P.M. Mclnnes* S.L. Wendt, Jr. 1 D.H. Retief 2 R. Weinberg 3

Department of Orthodontics 3Department of Biometry Louisiana State University School of Dentistry 1Department of Restorative Dentistry and Endodontology University of Connecticut School of Dental Medicine 2Department of Biomaterials University of Alabama School of Dentistry Received September 20, 1989 Accepted March 22, 1990 *Current address: Office of Extramural Research National Institutes of Health Building 3t, Room 5B35 Bethesda, MD 20892 Dent Mater 6:204-207, July, 1990

Abstract-The aim of this investigation was to evaluate the effect of dentin surface roughness on the shear bond strength of a dentin bonding agent. Seventy-five dentin samples were divided into five surface preparation groups: (1) 60-grit SiC; (2) 320-grit SiC; (3) 600-grit SiC; (4) 600-grit SiC followed by AI2O3; and (5) 320-grit SiC followed by a #245 carbide bur. The prepared dentin was treated with a dentin primer, and one coat of dentin bonding agent was applied and light-cured for 30 s. Each dentin specimen was mounted in a device with a split Teflon mold (I.D. = 3.5 mm, depth = 5.0 mm). Three increments of a restorative composite were placed, compressed firmly, and light-cured for 30 s in the mold. After 24 h of storage, the bonds were stressed to failure in a mechanical testing machine at a crosshead speed of 0.5 mm/min. Weibull analysis was used to obtain a shape factor and characteristic level for each group. The results showed that, with the possible exception of the 600-grit SiC and AI203 group, the grit size used for preparation of dentin specimens for shear bond strength testing in this study did not significantly affect bond strength. 204 M c I N N E S et al./BONDING TO D E N T I N

easurement of bond strength is dependent on many variables. The methods of measurement vary among laboratories, and extreme care needs to be taken in interpretation of results from different laboratories and different testing systems. Bonding to dentin remains significantly more difficult than bonding to enamel. Dentin is a heterogeneous material that varies according to tooth type and region (Aboush and Jenkins, 1984), distance from the amelo-dentinal junction (Causton, 1984), the nature of trauma and clinical experience prior to extraction (MjSr, 1983), and the time after extraction (Causton and Johnson, 1979). The laboratory techniques utilized to bond and subsequently break the s p e c i m e n s also affect the bond strength results. The methods by which the bond is achieved, e.g., bulk placement as opposed to incremental placement, application of pressure, and rate of load application, all play a role in the bond strengths achieved. The length of time that the bonded units are stored in water also affects bond strength, as does the use of thermocycling. The effect of surface roughness of tooth substrate on the bond strength to adhesive dental materials is controversial. Negm et al. (1981) reported that increasing the surface roughness of enamel decreased tensile bond strength to polycarboxylate c e m e n t b u t s i g n i f i c a n t l y i n c r e a s e d (p

Effect of dentin surface roughness on shear bond strength.

The aim of this investigation was to evaluate the effect of dentin surface roughness on the shear bond strength of a dentin bonding agent. Seventy-fiv...
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