Bonding Efficacy of Single-step Self-etch Systems to Sound Primary and Permanent Tooth Dentin

Abstract

Single-step self-etch systems are capable of producing a predictable bond to primary dentin, although the bond strength was found to be lower than permanent dentin. SUMMARYCurrently, there is little information regarding the bonding efficacy of single-step self-etch systems to primary tooth dentin. This study examined the microtensile bond strength of single-step self-etch systems (Clearfil tri-S Bond and One-Up Bond F Plus) to sound primary and permanent tooth dentin. Adhesives were applied to flat samples of primary and permanent tooth dentin, and resin composites were bonded according to the manufacturers' instructions. After 24 hours of storage in distilled water at 37°C, hour glass-shaped specimens were produced. They were subjected to microtensile testing at a crosshead speed of 1.0 mm/minute. The results were analyzed using 2-way analysis of variance (ANOVA) followed by the Tukey HSD post-hoc test (α α=0.05). Field-emission scanning electron microscopy (FE-SEM) observations of the adhesive-treated dentin surfaces and the resin/dentin interface were also conducted. The bond strengths of primary tooth dentin were significantly lower than that of permanent tooth dentin for both self-etch systems: 44.7 ± 10.4 versus 54.3 ± 9.0 MPa for Clearfil tri-S Bond and 40.6 ± 9.9 versus 50.0 ± 8.7 MPa for One-Up Bond F Plus (p<0.001). There was no statistically significant interaction between the type of adhesive system and the dentin substrate (p=0.957). Although there was no statistically significant difference in the mean values among the different adhesive systems (p=0.094), there was a statistically significant difference in mean values among the different dentin substrates (p<0.001), which were lower for primary tooth dentin than for permanent tooth Operative Dentistry dentin. The failure modes were also independent of the type of dentin but dependent on the adhesive systems, an equal distribution among the 3 types of failure for Clearfil tri-S Bond and cohesive failures in adhesives for One-Up Bond F Plus. FE-SEM observations of dentin to which adhesive had been applied revealed that the smear layer had been removed and the collagen fibers exposed. Though the bond strengths to primary tooth dentin were lower than to permanent tooth dentin, excellent adaptation of the single-step selfetch systems to both dentin substrates was observed by FE-SEM. Further studies are required to determine the long-term clinical performance of these adhesive systems when applied to primary tooth dentin.

Chlorhexidine does not increase immediate bond strength of etch-and-rinse adhesive to caries-affected dentin of primary and permanent teeth

“…Differences in composition, tubular density, intrinsic moisture and dentinal permeability (21) between primary and permanent teeth may be responsible for the lower bond strength values obtained in sound primary dentin, which were similar to those of previous studies that also found worst results to primary dentin (8,9).…”

“…Previous researches in permanent teeth have reported lower values of bond strength to caries-affected dentin compared with sound dentin (2,3), due to the presence of acid-resistant whitlockite minerals within the dentinal tubules (2,7) and intertubular dentin partially demineralized (3,8). Nevertheless, the results obtained in primary teeth are still controversial (4)(5)(6).…”

“…Some studies have shown lower bond strength values to primary dentin (8,9), while others have found similar values (10) or even superior performance in primary dentin (11).…”

Tensile bond strength of different adhesive systems to enamel and dentin

“…This thin layer is possibly mainly responsible for the high bond strength produced by this adhesive system, which may indicate that hybrid layers do not have to be thick to be strong, as long as the collagen fibrils are optimally infiltrated by resin. No correlation between hybrid layer thickness/morphology and bond strength could be found (15,16). In the present study, the self-etching systems showed different bond strength to dentin, i.e., Clearfil had higher means than Prime&Bond NT/NRC.…”

Microtensile bond strengths of single-step self-etch adhesive systems to bovine dentin

“…The resistance against initiation of crack growth and propagation depends on the geometry and the load configuration of the specimen. The use of the microtensile bond strength test to evaluate bond strength of adhesive systems has been widely accepted (18)(19)(20). Smaller specimens contain a lower number of initial defects and have more homogeneous stress distributions; hence, bond strengths as well as adhesive failure between the adhesive and dentin can be examined more accurately.…”