title: In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases and interface treatments. "Post-fatigue adaptation of indirect composite restorations".
abstract: The present study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II indirect composite restorations, after simulated occlusal loading. Thirty-two class II inlay cavities were prepared on human third molars, with margins located in cementum. A 1-mm composite base extending up to the cervical margins was applied on all dentin surfaces in the experimental groups; impressions were made and composite inlays fabricated. The following experimental conditions were tested: no liner (control group), flowable composite treated with soft air abrasion (experiment 1), flowable composite sandblasted (experiment 2) and restorative composite sandblasted (experiment 3). All specimens were submitted to 1,000,000 cycles with a 100-N eccentric load. Tooth-restoration margins were analysed semi-quantitatively by scanning electron microscopy before and after loading; internal adaptation was also evaluated after test completion. The percentage of perfect adaptation in enamel was 79.5% to 92.7% before loading and 73.3% to 81.9% after loading. Perfect adaptation to dentin was reduced before loading (54.8% to 77.6%) and after loading (41.9% to 63%), but no difference was found among groups for pre- and post-loading conditions. No debonding occurred between the base and composite luting. A significant, negative influence of cyclic loading was observed. The results of the present study support the use of flowable or restorative composites as base/liner underneath large class II restorations. Soft air abrasion represents a potential alternative to airborne particle abrasion for treating cavities before cementation. The application of a composite base underneath indirect composite restorations represents a feasible non-invasive alternative to surgical crown lengthening to relocate cavity margins from an intra-crevicular to supra-gingival position.
authors: Division of Cariology and Endodontology, School of Dentistry, University of Geneva, 19 Rue Barthélémy Menn, 1205 Geneva, Switzerland. giovanni.rocca@unige.ch
authors: Giovanni Tommaso
authors: GT
authors: Rocca
authors: Ladislav
authors: L
authors: Gregor
authors: Maria Jose
authors: MJ
authors: Sandoval
authors: Ivo
authors: I
authors: Krejci
authors: Didier
authors: D
authors: Dietschi
mesh_terms: D020906:Air Abrasion, Dental; D003188:Composite Resins; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D008964:Molar, Third; D019279:Resin Cements; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C469607:OptiBond FL; D019279:Resin Cements; C111840:flowable hybrid composite; C507210:premise composite resin