LABORATORY EVALUATION OF THE GLUMA 3-STEP BONDING SYSTEM

Purpose: To determine in vitro (1) the shear bond strengths (SBS) of t he modified Gluma system to enamel and dentin; (2) the qualitative and the quantitative microleakage (ML) of Class V preparations on the cem ento-enamel junction (CEJ) and in dentin, respectively, restored with the Gluma system; and (3) the effect of the system's components on ena mel and dentin by scanning electron microscopy. Materials and Methods: Seventy-five extracted human maxillary permanent central incisors and 75 permanent first and second molars were embedded in brass tooth cup s with cold-cure acrylic resin. The facial surfaces of the anterior an d the occlusal surfaces of the molar teeth were ground wet on 180- fol lowed by 600-grit silicon carbide paper. Demarcated sites on the surfa ces were treated according to the manufacturer's instructions and Peka fill composite was bonded to the treated surfaces. Fifteen specimens p repared on enamel were removed 1 minute after cure (A) and the SBS det ermined. The remaining specimens were removed 15 minutes after final c ure, stored in saline at 37 degrees C for 24 hours (B), for 1 week wit hout (C) and with temperature cycling (D), and for 4 weeks (E). Simila r regimens were used for dentin, groups F, G, H, I and J. The SBS were determined and expressed in MPa. The data were analyzed by ANOVA, Stu dent-Newman-Keuls and t-tests. For the qualitative ML evaluation, Clas s V cavities were prepared on the CEJ of 30 human premolars and restor ed with Gluma/Pekafill. After thermocycling in 0.5% basic fuchsin, the teeth were sectioned and ranked according to the degree of microleaka ge. Class V cavities were prepared on the facial root surfaces of 15 h uman premolars and restored. The ML was determined quantitatively by a spectrophotometric dye-recovery method and expressed as mu g dye/rest oration. Results: The mean +/- SD of the SBS in MPa were: A: 14.6 +/- 2.2; B: 21.2 +/- 1.6; C: 20.5 +/- 1.4; D: 24.2 +/- 2.0; E: 22.8 +/- 3. 7; F: 7.0 +/- 2.0 G: 16.1 +/- 4.0; H: 15.6 +/- 3.7; I: 10.9 +/- 3.3; J : 14.4 +/- 3.3. The quantitative ML was 1.00 +/- 0.39 mu g dye/restora tion. The lowest SBS were obtained on specimens tested after 1 minute. Temperature cycling had a significantly adverse effect on the SBS to dentin (P=0.0003). Etch patterns conducive to bonding were produced on the enamel. The resin system penetrated into the dentin tubules.