The Effect of Thermocycling on the Adhesion of Self-etching Adhesives on Dental Enamel and Dentin

Abstract

Aim The aim of the present study was to investigate the effectiveness of one total-etch self-priming adhesive and two one-step self-etching adhesive systems on the adhesion of a resin composite to both dentin and enamel. The effect of thermocycling on the adhesion was also investigated. The null hypothesis tested was thermocycling would not affect bond strengths to enamel and dentin treated with self-etching adhesives or a total-etch adhesive. Methods and Materials Two single-step self-etching adhesives [Xeno III (XE3) and Prompt L-Pop (PP)] and one two-step total-etch adhesive system (Prime & Bond NT) (P&B NT) were used in this study. Thirty cariesfree unrestored human third molars were used to make specimens of enamel and dentin. Different adhesives were applied on enamel and dentin surfaces according to the manufacturer's instructions then hybrid composite restorative material was condensed on the surface using a mold. The bonded specimens were stored in distilled water at 37°C for 24 hours before being tested. Half of the bonded specimens were tested for shear bond strength without thermocycling. The other half of the test specimens were thermocycled using a thermocycling apparatus in water baths held at 5°C and 55°C with a dwell time of one minute each for 10,000 cycles prior to shear testing. The mean shear bond strength before and after thermocycling was calculated, and the results were subjected to two-way analysis of variance (ANOVA) and repeated measure design to show the interaction between different materials and different times. Results The results showed shear bond strength on both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. Conclusions The null hypothesis tested “thermocycling would not affect bond strengths treated with selfetching adhesives” was rejected. Furthermore, the study revealed the following: The shear bond strength to both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. XE3 achieved the highest bond strength to both enamel and dentin (26.994±1.17 and 25.22±1.26, respectively). XE3 showed even better bonding after thermocycling to enamel and dentin than the total-etching system or PP. Although PP bonded to enamel showed lower shear bond strength value than XE3, it has durable bond strength even after thermocycling. Citation El Araby AM, Talic YF. The Effect of Thermocycling on the Adhesion of Self-etching Adhesives on Dental Enamel and Dentin. J Contemp Dent Pract 2007 February;(8)2:017-024.

Adhesion of conventional and simplified resin-based luting cements to superficial and deep dentin

“…Another possibility for the decrease in bond strength after thermocycling could be attributed to increased water absorption or solubility of the composite, or both. Not all studies support these outcomes [43]. The results of this study at least for Panavia F 2.0 and Superbond C&B was lower than a previous study (29 to 31 MPa for SD and 10 to 18 MPa for DD, respectively) where tensile test was used and no thermocycling was practiced [9].…”

“…Thermal stresses generate stresses due to differences in the coefficient of thermal expansions of the cement and can result in bond failure at the tooth-restorative interface [43]. Another possibility for the decrease in bond strength after thermocycling could be attributed to increased water absorption or solubility of the composite, or both.…”

Effect of thermal cycling on the bond strength of self-adhesive cements to fiber posts

“…However, bond strength of G-Cem increased after thermal challenging. Thermal changes will cause expansion/contraction stresses within the material [22,41], which may affect the adhesive stability, but the cement expansion will also create frictions along the root canals that are thought to improve its mechanical retention [42]. After setting, G-Cem showed a porous appearance at the adhesive interface [27].…”

Dentin and enamel bond strengths of dual-cure composite luting agents used with dual-cure dental adhesives

“…Other studies have shown no or materialspecific effects of thermocycling. [24][25][26][27] One possible limitation of the protocol used in this study is the relatively short duration of the baths (30 s), which might not have been enough to result in thermal stresses at the bonded interface. Additionally, thermal changes are more likely to induce stresses in restorations placed in complex preparations (high C-factor), which was not the case in this study.…”