ABSTRACT
PURPOSE: To evaluate the long-term influence of the shear bond strength (SBS) on glass-ionomer cement (GIC) to Er:YAG-irradiated and bur-prepared enamel. MATERIALS AND METHODS: One hundred and ninety human premolar and molars were selected and the crowns were sectioned. Samples were divided into five groups, according to surface treatments: bur preparation (B); bur preparation, etching with 37% phosphoric acid (BA); laser preparation (L); laser preparation, etching with 37% phosphoric acid (LA); laser preparation, twice irradiating with laser at low (150 mJ, 10 Hz; water spray 10 ml/min) (LL). Samples were subdivided according to the number of thermo-cycles (TCs)-500 TCs, 1,000 TCs, 3,000 TCs, and 5,000 TCs. The SBS between GIC and enamel was measured using a universal testing machine; failure patterns were analyzed with stereomicroscope. The enamel surfaces and the patterns of the junction between GIC and enamel were observed by scanning electronic microscopy (SEM). RESULTS: The SBS of L group was higher than that for the B group (P < 0.05). The failure mode analysis demonstrated a cohesive failure within the cement in BA and LA groups, but the SBS of LA group was higher than that for the BA group (P < 0.05). LL had a similar effect on SBS compared with LA. Thirty-seven percent phosphoric acid had greatly increased SBS of GIC to enamel (P < 0.05). The SBS was significantly affected by thermocycling (TC) (P < 0.05). CONCLUSION: Our results showed that Er:YAG irradiated significantly increased the SBS on GIC to enamel than bur-prepared enamel. In addition, 37% phosphoric acid pretreated also significantly increased the SBS on GIC to enamel. However, the results of these in vitro tests were limited, and extrapolation to the clinical situation was difficult. Thus, further studies were needed on this subject to simulate the highly complex and dynamic environment in the analysis. Lasers Surg. Med. 48:978-984, 2016. © 2015 Wiley Periodicals, Inc.
Subject(s)
Dental Bonding/methods , Dental Enamel/radiation effects , Glass Ionomer Cements/chemistry , Hot Temperature , Lasers, Solid-State , Shear Strength , Dental Enamel/chemistry , Dental Enamel/diagnostic imaging , Humans , In Vitro Techniques , Microscopy, Electrochemical, Scanning , Random AllocationABSTRACT
Erbium:yttrium-aluminum-garnet (Er:YAG) laser preparation of tooth cavities for restoration is an increasingly popular method, but its compatibility with existing composite material bonding protocols has not been fully defined. This study evaluated the effect of laser and etchant pretreatments on the performance of one-bottle self-etch adhesives in Er:YAG laser-prepared dentin. Eight groups of 20 extracted teeth were established to investigate bonding in tested dentin disks. Various combinations of laser preparation (with/without), pretreatment (none/acid-etch/low-fluence Er:YAG irradiation), and self-etching adhesive (G-Bond Plus or Xeno V) were tested. Samples were then restored with composite resin and subjected to a tensile bond strength (TBS) test. We also performed scanning electron microscopy (SEM) on dentin disks from some of these groups before and after adhesive application to evaluate their microscopic morphological appearance. Statistical analysis (Dunnett T3 test coupled with the general linear model at 5% significance level) revealed that the laser preparation of dentin did not impact on TBS (p = 0.914), whereas pretreatment with either phosphoric acid (p < 0.0001) or low-fluence Er:YAG laser irradiation (p < 0.0001) significantly increased TBS, although there was no difference between them in their respective elevation of TBS. SEM analysis demonstrated that both acid and laser pretreatments reduced irregularities and produced a more homogeneous surface. Er:YAG laser preparation does not compromise the efficacy of one-step self-etch dentin adhesives, and pretreatment with phosphoric acid or low-fluence Er:YAG laser can significantly increase the TBS of adhesion to this irradiated dentin.
