Effect of high-concentrated bleaching agents on the bond strength at dentin/resin interface and flexural strength of dentin

Abstract

<jats:p>This study evaluated the effect of bleaching agents on bond strength at the dentin/resin interface and the flexural strength of dentin. Forty maxillary canines were selected for the study. In the shear strength test, 40 slabs of intracoronary dentin (5 x 5 mm) obtained from buccal surfaces of the crowns were included in acrylic resin. In the flexural strength test, 40 dentin bars (8 x 2 x 2 mm) were obtained from the roots. The 40 hemi-sections of the lingual surface were prepared for scanning electron microscopy (SEM). The specimens were divided into 4 groups according to the bleaching protocol (n=10): Unbleached (control), Sodium perborate + 20% hydrogen peroxide (SP + 20% HP), 37% carbamide peroxide (37% CP) and 38% hydrogen peroxide (38% HP). After 7 days, the bond strength specimens were restored and tested. Dentin bars were bleached and subjected to a three-point bending test. Data (MPa) were analyzed by ANOVA and Tukey's test (α=0.05). In the shear test, the control group was superior (p&lt;0.05) to the bleached groups, which, in turn, were statistically similar (p&gt;0.05). In the flexural strength test, the control group also had the highest values and differed significantly from the other groups (p&lt;0.05). SEM revealed smear layer in all groups, with fissures in the bleached specimens. SP + 20% HP and 38% HP showed discontinuous interfaces with few tags. In conclusion, bond strength of restorative material to dentin and flexural strength of dentin were reduced after the use of high-concentration bleaching agents.</jats:p>

Physical properties of two bis-acryl interim materials: color stability, flexural strength and shear bond strength to flowable composite resin as add-on material

“…Flexural strength test usually follow the ISO 4049 standard that state specimen with 25 x 2 x 2 mm. The dimensions used in the present study are different from the ISO, however also observed in prior studies [20][21][22] . Other dimensions are also used in the literature, such at Vieira et al 22 (2012) and Firoozmand and Pagani 23 (2009).…”

Effect of Blood Contamination and Decontamination Protocols on Acetone‐Based and Ethanol‐Based Total Etch Adhesive Systems

“…This hypothesis supports the observation of absence of hybrid layer and resin tags and decreased MTBS observed in this study. Vieira and colleagues also reported the absence of resin tags and discontinuity areas at the interface when 38% H 2 O 2 was applied on intact dentin. Changes in Ca to P ratio, reduction in the organic components of dentin by protein oxidation, and hydroxyl radical‐mediated damage to organic components of dentin have also been proposed to be responsible for reduced MTBS.…”

Effect of ozone gas on the shear bond strength to enamel

“…Due to its strong oxidizing effect, ozone might have negative consequences on resin-tooth adhesion, since oxygen is a well-known polymerization inhibitor 9 . It has been demonstrated that oxygen and other oxidant agents (such as bleaching agents) have a negative influence on dental adhesives bond strength 29 .…”