Abstract
Objectives The aim of this study was to evaluate the shear bond strength and the nanoleakage expression of CLEARFIL Universal Bond Quick and Tetric N-Bond adhesive systems bonded to dentin. Materials and Methods 100 freshly extracted human premolar teeth were utilized. The teeth were sectioned to expose dentin. All dentin specimens were assigned into 4 experimental groups; 2 groups had Universal Bond Quick (Universalself group) and Tetric N-Bond (Tetricself group) applied in the self-etch mode, while 2 groups had Universal Bond Quick (Universaltotal group) and Tetric N-Bond (Tetrictotal group) applied in the total-etch mode. n = 15 for shear bond strength and n = 10 for nanoleakage experiment. One-way ANOVA and Kruskal-Wallis test were utilized to analyze the shear bond strength test and the nanoleakage expression, respectively. Results The highest significant bond strength value was recorded by the Tetricself specimens (p < 0.05) when compared to the remaining three groups. There were no statistically significant differences between the shear bond strength values recorded in the Tetrictotal, Universalself, and Universaltotal groups (p < 0.05). Both bonding systems applied in the self-etch mode (Universalself, Tetricself) had no silver nitrate deposits in the hybrid layer and the hybrid layer-adhesive interface (p < 0.001); however, both bonding systems applied in the total-etch mode (Universaltotal, Tetrictotal) had silver nitrate deposits in the hybrid layer, the hybrid layer-adhesive interface, and the bonding layer (p < 0.001). Conclusion Applying the Universal Bond Quick and Tetric N-Bond in the self-etch mode exhibited better results in terms of nanoleakage expression. Universal Bond Quick showed the stability of the shear bond strength to dentin when applied using the total-etch or self-etch modes. Tetric N-Bond showed significant deterioration in bond strength when applied in the total-etch mode and exhibited the highest bond strength when applied in the self-etch mode.
Highlights
The introduction of self-etch adhesives in the late 1980s revolutionized the science of dental adhesives; many advantages were associated with the use of the self-etch approach to the dentin surface which may include its ease of use [1] and less technique sensitivity [1]
The results show that the application mode affected the Tetric N-Bond system (p < 0:001) while it did not affect the Universal Bond Quick system (p < 0:05)
A previous study [18] comparing the reliability of both tests highlighted that despite the low bond strength values, the shear bond strength test is capable of reliable and reproducible results and that it is a suitable method for comparing the bond strength of various dental adhesive systems [18]
Summary
The introduction of self-etch adhesives in the late 1980s revolutionized the science of dental adhesives; many advantages were associated with the use of the self-etch approach to the dentin surface which may include its ease of use [1] (by decreasing the number of steps needed for the dentin bonding procedures) and less technique sensitivity [1] (by not adopting the wet bonding technique utilized with the total-etch approach).the less aggressive acidic treatment associated with the self-etch approach (compared to the total-etch approach) preserved the smear plugs into the dentinal tubules decreasing the deteriorating effect of the pulpal pressure on the adhesive-dentin interface [2, 3].One of the unique features associated with the use of self-etch adhesives possessed is its capability to simultaneously condition and penetrate the dentin collagen network [1, 4, 5]. Application of the self-etch adhesives on dentin cervical cavosurface margins in Class V cavities rendered these margins resistant to a simulated caries attack when compared to etching these margins with phosphoric acid prior to bonding [6]. All of these advantages were reflected as a clinical success of the mild self-etch adhesives in the form of less postoperative pain symptoms and prolonged clinical performance for most of the 2-step mild self-etch systems [1, 4]. This prolonged clinical performance decreased the demand for replacing the restorations due to recurrent caries and preserve the integrity of the remaining tooth structures and comply with the minimal intervention concepts that advocate the preservation of tooth structures [7]
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