ENAMEL AND DENTIN BOND STRENGTH AND BONDING MECHANISM TO DENTIN OF GLUMA CPS TO PRIMARY TEETH

This study evaluated the shear bond strength to enamel and dentin and bonding mechanism to dentin of Gluma CPS bonding system to primary tee th enamel and dentin. Pekafill hybrid composite was used. Ten specimen s were immersed in deionized water at 37 degrees C for twenty-four hou rs and ten other specimens were subjected to a thermocycling procedure (2000 cycles between 5 degrees and 55 degrees C, dwell time fifteen s econds). After water storage or thermocycling, the bonded cylinders we re sheared and the bond strength calculated. After debonding, the fail ure sites of all samples were evaluated microscopically. The data were analyzed with an ANOVA and Student-Newman-Keuls test. In ten other pr imary molars, the buccal surfaces were ground flat on wet SiC papers t o expose peripheral dentin. Cylindrical buttjoint cavities were prepar ed with a cylindrical diamond bur. The cavities were treated with Glum a CPS and filled with Pekafill as described above. After fifteen-minut e water storage, filling excess was removed and marginal integrity and bonding mechanism of five restorations was examined with a light micr oscope. Five other restorations were evaluated after storage in water at 37 degrees C for twenty-four hours. Maximal gap widths and hybrid l ayer thickness were determined. The results showed that thermocycling did not affect the shear bond strength to enamel or dentin. There was a statistically significant difference (p<0.05) between the shear bond strength values obtained in enamel and dentin. The maximal gap width was not significantly different between specimens that were stored in water for fifteen minutes or twenty-four hours. The average hybrid lay er thickness was 11.7 +/- 1.1 mu m. AU specimens revealed a resin cohe sive failure very close to enamel or dentin surface. The etch patterns produced on the abraded enamel surface were uniform and deeper as com pared to the sample that was pumiced. This was also confirmed in the e poxy replicas.