Thermal and mechanical load cycling on microleakage and shear bond strength to dentin.
This study evaluated the influence of mechanical and thermal cycling on microleakage at the cervical margins of proximal slot restorations and shear bond strength on flat dentin surfaces. Microleakage Evaluation: One hundred and twenty slot cavity restorations were performed on bovine incisors. The restorations were randomly divided into four groups (n = 30): control (no thermal and mechanical load cycling), thermal cycling (2,000 cycles, 5 degrees C-55 degrees C), mechanical load cycling (50,000-80N) and thermal and load cycling (2,000 5 degrees C-55 degrees C/50,000-80N). The specimens were sealed with acid resistant varnish, leaving a 1-mm window around the cervical margin interface. To detect marginal leakage, a 2% methylene blue buffered solution was used for four hours. The specimens were sectioned longitudinally and qualitatively evaluated by stereomicroscopy (45x) following a ranked score for the dentin cervical margin. The data were analyzed by Kruskal-Wallis test (alpha = 0.05). Shear Bond Strength Evaluation (SBS): Eighty bovine incisors were embedded and polished to obtain a flat standard surface on dentin. The surfaces were restored with Single Bond adhesive system and a resin composite subsequently inserted in a bipartite Teflon matrix. The specimens were randomly divided into the four groups (n = 20) described above for microleakage. Shear bond strengths were measured in a universal testing machine with a crosshead speed of 0.5 mm/minute. The data were analyzed by one way ANOVA test (alpha = 0.05). No statistically significant influence of thermocycling, mechanical load cycling or the combination was observed for both microleakage and shear bond strength.
Bedran-de-Castro
Ana Karina Barbieri
AK
University of North Carolina, School of Dentistry, Chapel Hill, NC, USA.
Cardoso
Paulo Eduardo Capel
PE
Ambrosano
Glaucia Maria Boni
GM
Pimenta
Luiz André Freire
LA
D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000145:classification*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D008422:Materials Testing; D008751:Methylene Blue; D011897:Random Allocation; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013696:Temperature; D019237:Tooth Cervix / Q000648:ultrastructure; D016474:Weight-Bearing
D004396:Coloring Agents; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D008751:Methylene Blue