Evaluation of pH, ultimate tensile strength, and micro-shear bond strength of two self-adhesive resin cements

Abstract

The aim of this study was to evaluate the pH, ultimate tensile strength (UTS), and micro-shear bond strength (µSBS) of two selfadhesive resin cements to enamel and dentin. Sound bovine incisors (n = 10) and two self-adhesive resin cements (i.e., RelyX U-100 and seT PP) were used. The pH of the resin cements was measured using a pH-indicator paper (n = 3). Specimens for UTS were obtained from an hourglass-shaped mold. For µSBS, cylinders with internal diameter of 0.75 mm and height of 0.5 mm were bonded to the flat enamel and dentin surfaces. Bonded cylinders were tested in the shear mode using a loop wire. The fracture mode was also evaluated. The cement seT PP showed a low pH; U-100 showed significantly higher UTS (49.9 ± 2.0) than seT PP (40.0 ± 2.1) (p < 0.05) and high µSBS to enamel (10.7 ± 3.7). The lowest µSBS was found for seT PP to dentin (0.7 ± 0.6); seT PP to enamel (4.8 ± 1.7), and for U-100 to dentin (7.2 ± 1.9), showing an intermediate µSBS value (p < 0.05). Adhesive failure was the most frequently observed failure mode. The resin cement that presented the lowest pH and UTS also presented the lowest micro-shear bond strength to enamel and dentin.

Effect of Enamel and Dentin Surface Treatment on the Self-Adhesive Resin Cement Bond Strength

“…Different sample sizes have been used in similar studies. For example, Costa et al (16) used 10 samples per group while Kasraei et al (19) prepared 9 samples per group. In the present study, 12 samples per group were sufficient to provide statistical power.…”

“…The bond strength achieved by self-adhesive resin cements is lower than those achieved by conventional resin cements (2,6,8,11,12) and adhesive systems for direct resins (1). This is due to 4 factors: 1. acidic monomers have low etching capacity, minimizing surface demineralization (2,5,6,8,13,14); 2. buffering effect of the minerals in the dentin that neutralizes the cement pH (15,16,17); 3. high viscosity of the cement that hinders its penetration into the interfibrillar space (4,5,9,18); and 4. nonremoval or incomplete removal of the smear layer, which promotes a weak bond with the resin's intermediate layer (5,11,13,14,19).…”

Effect of 2% chlorhexidine treated coronal dentin on bond strength of two self-adhesives cements

“…This is due to four primary factors: (1) acidic monomers have low etching capacity, minimizing the surface demineralization; (2) the buffering effect of the minerals present in the dentin can neutralize the pH of the cement; (3) the high viscosity of the cements hinders their penetration into the interfibrillar space; (4) non-removal or incomplete removal of the smear layer promotes a weakly bonded reinforced resin intermediate layer [5,6,11,16,17].…”

“…The establishment of integrity and stability within these complex interfaces increases bond strength and fracture resistance of the restoration and the tooth structure [9,17], while guaranteeing long-term success of the restorative treatment. Deterioration of the hybrid layer can lead to microleakage, resulting in staining, recurrent caries, postoperative sensitivity, or debonding of the restoration [5,14].…”

Tensile Bond Strength of Self Adhesive Resin Cement After Various Surface Treatment of Enamel

“…This makes the luting procedure less technique-sensitive and decreases postoperative sensitivity. Many claim superiority in retentive strength, working and handling characteristics [11,12].…”