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.

Influence of proximal box elevation on the marginal quality and fracture behavior of root-filled molars restored with CAD/CAM ceramic or composite onlays

“…marginal adaptation compared to rigid materials, while Rocca et al [21] found that composite type exerted no significant influence on marginal adaptation. Furthermore, the application of three consecutive 1-mm-thick layers of a highly filled restorative composite provided the best marginal quality to dentin, whereas self adhesive resin cements performed significantly more poorly [11].…”

“…According to recent in vitro studies performed on non-endodontically treated molars, PBE did not necessarily influence the marginal adaptation compared to indirect restorations without the placement of a proximal composite base [11,12,21]. However, there are currently no data available regarding how composite bases in deep sub-gingival areas impact the marginal quality and fracture behavior of root canal filled teeth with indirect restorations.…”

Fatigue behavior of resin-modified monolithic CAD–CAM RNC crowns and endocrowns

“…During the first phase, all of the restorations were subjected to a thermo-mechanical cycling loading in a computer-controlled masticator. In order to mimic invivo testing conditions, the low masticatory force of 49 N was applied for 600 000 cycles at 1.7 Hz, corresponding to approximately 2.5 years of mild clinical function (without peaks) in premolar region [20][21][22]. A more clinically relevant number of cycles of 10 6 at low masticatory loads -corresponding to approximately 5 years of function -has been suggested before [23].…”

Effect of temporary cements on the bond strength of a resin cement to a pre-hybridized dentin

“…Various authors have evaluated methods for removal of provisional cement in vitro. Reviewing these studies, it was found that the highest bond strength values were reported with soft-air abrasion (ROCCA et al, 2012), airborne particle abrasion with aluminum oxide (DILLENBURG et al, 2009. MAGNE et al, 2007.…”