Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-04-05, 13:01:42 | version 1.38.0
| research 14 laser 1 2016 Preparation of samples for scanning electron microscopy The samples discs were split in half (MD) with a diamond blade mounted on the handpiece resulting in restored hemi-discs. The hemi-discs were pre- pared to be observed on the SEM. The observations were made using the electron microscope scan- ning—FESEM(JEOLJSM6301F)at10–15 kVandwere focussed in the area resin-dentin interdiffusion. The electron microscopy photomicrographs were taken in a variation of 300 x and 5,000 x magnifications. Shear Bond Strength (SBS) test The Shear Bond Strength was performed using the Instron device connected to a computer, (sys- tem developed at the University of California, San Francisco). Shear Bond Strength was tested at 1 mm/min. Statistical analysis The Shear Bond Strength values were analysed using the Shapiro-Wilk test to control the normal- ity assumptions, because the number of the sam- ple was lower than thirty. The homogeneity assump- tions were controlled by the Levene test. Although the data were normally distributed, the Levene test rejected the homogeneity of the variances. Therefore, the Welch test was applied and the Games-Howell post-hoc test was used to compare pairwise, with a confidence interval of 95 %. Results Shear Bond Strength test (SBS test) All statistical analyses were performed using SPSS version 21.0 (SPSS Inc., Chicago, IL, USA). Group 2 was the one with the highest Shear Bond Strength mean (4.76 ± 3.99 MPa), although the standard deviation is the highest, and the Group 3 had the lowest Shear Bond Strength mean (0.81 ± 0.93 MPa), as we can see in the graph (Fig. 1). This means of the Shear Bond Strength of the Control Group (1.87 ± 1.61 MPa), of Group 2 (4.76 ± 3.99 MPa) and of the Group 3 (0.81 ± 0.93 MPa), were not statistically different be- tween each other (p > 0.05). Scanning electron microscopy Control Group In these dentin samples we saw a regular sur- face, with resin tags in the surface of the dentin going through the open dentinal tubules. The resin tags appeared to be sectioned, showing an adhe- sive failure (Figs. 2 and 3). Group 2 In the analysis of the samples of Group 2, a rougher dentin surface was noted, with several resin tags. It was possible to see a hybrid layer for- Fig. 2: SEM of the dentin surface without laser preparation (Control), showing the micromorphological aspects of the bonding region produced by Vertise Flow™. Note the regular surface and the wide dentinal tubules with resin tags (x 1,500). Fig. 3: SEM of the dentin surface without laser preparation (Control), showing the micromorphological aspects of the bonding region produced by Vertise Flow™. Note the sectioned resin tags in the dentin surface (x 1,500). Fig. 4: SEM of the dentin surface pre-treated with Er,Cr:YSGG laser from Group 2, showing long resin tags with lateral branches (x 1,500). Fig. 5: SEM of the dentin surface pre-treated with Er,Cr:YSGG laser from Group 2, showing long resin tags with lateral branches. The formation of a gap along the interface was observed (x 5,000). Fig. 2 Fig. 4 Fig. 3 Fig. 5 12016