Morphology of the Dentin-resin Interface yielded by Two-step Etch-and-rinse Adhesives with Different Solvents.

AIM: The study aimed to analyze the morphology of the dentin-resin interface yielded by two-step etch-and-rinse adhesive systems with different solvents and compositions. MATERIALS AND METHODS: A total of 32 dentine disks were prepared and randomly assigned to four groups of one-bottle etch-and-rinse adhesive systems containing different solvents: group I, Adper Scotchbond-IXT™ (ethanol/water); group II, XP-Bond™ (tertiary butanol); group III, Prime and Bond NT® (acetone); and group IV, One Coat bond® (5% water). Adhesive systems were applied onto dentin disks, which were then thermal cycled, divided into two hemi-disks (n = 16), and prepared for field-emission scanning electron microscopy to examine the dentin-resin interdiffusion zone. Microphotographs were scanned and data were processed. Data were compared with analysis of variance multivariant test after Kolmogorov-Smirnov and Shapiro-Wilk tests using Statistic Package for the Social Sciences. RESULTS: The adhesive layer thickness average found was group I: 45.9 ± 13.41 urn, group II: 20.6 ± 16.32 urn, group III: 17.7 ± 11.75 urn, and group IV: 50.7 ± 27.81 urn. Significant differences were found between groups I and IV and groups II and III (p < 0.000). Groups I (3.23 ± 0.53 µm) and II (3.13 ± 0.73 µm) yielded significantly thicker hybrid layers than groups III (2.53 ± 0.50 µm) and IV (1.84 ± 0.27 µm) (p < 0.003). Group III presented a less homogeneous hybrid layer, with some gaps. Tag length average was greater in groups II (111.0 ± 36.92 µm) and IV (128.9 ± 78.38 µm) than in groups I (61.5 ± 18.10 µm) and III (68.6 ± 15.84 µm) (p < 0.008). CONCLUSION: Adhesives systems with different solvents led to significant differences in the dentin-resin interface morphology. Solvents role in adhesives bond strength should be considered together with the other adhesive system components. CLINICAL SIGNIFICANCE: The adhesive containing tertiary butanol, in addition, seems to originate a good-quality hybrid layer and long, entangled tags and also appears to have greater ability to originate microtags, which may indicate higher bond strength.

Shear bond strength and SEM morphology evaluation of different dental adhesives to enamel prepared with ER:YAG laser.

CONTEXT: Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching. AIMS: Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values. SUBJECTS AND METHODS: One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I - 37% phosphoric acid (PA)+ ExciTE(®); Group II - ExciTE(®); Group III - AdheSE(®) self-etching; Group IV - FuturaBond(®) no-rinse. NR; Group V - Xeno(®) V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min. STATISTICAL ANALYSIS USED: One-way ANOVA and post-hoc tests (P < 0.05). For the morphology evaluation, specimens were immersed in Ethylenediamine tetraacetic acid (EDTA) and the etching pattern analyzed under Scanning Electron Microscope (SEM). RESULTS: Mean bond strengths were Group I - 47.17 ± 1.61 MPa (type I etching pattern); Group II - 32.56 ± 1.64 MPa, Group III - 29.10 ± 1.34 MPa, Group IV - 23.32 ± 1.53 MPa (type III etching pattern); Group V - 24.43 MPa ± 1.55 (type II etching pattern). CONCLUSIONS: Different adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE(®) and ExciTE(®) without condition with PA. FuturaBond(®) NR and Xeno(®) V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used.