IADR Abstract Archives
Bonding Interface Affects Load-bearing Capacity of Bi-layered Composites
Objectives: Bulk-fill type composites are occlusally covered with hybrid-type composites. Dentin-replacing composites such as bulk-fill type SDR and fiber-reinforced everXPosterior (EXP) are used in this approach. In such a bi-layered composite system, composite layer thicknesses and their interfacial adhesion are expected to influence the strength of the system. Thus, this study aimed to evaluate the effect of thickness and interfacial adhesion of the composite layers on the load-bearing capacity of the system.
Methods: A total of 120 cylindrical specimens of bi-layered structure were prepared. Three different occlusal-thicknesses (1, 1.5 and 2mm) were fabricated using hybrid-type composite GænialPosterior (GP) and placed on base composites of everXPosterior (EXP) and SDR (total height:5mm). Adhesion between the layers was based on either an O2-inbited layer for optimal-adhesion (OA) or a polished surface for deteriorated-adhesion (DA). Adhesion of the layers was confirmed by debonding test (“shear-bond-strength-test”, SBS). The specimens (n=10) were light-polymerized before static-loading with a steel ball (Ø 4.0mm) until fracture. Fracture patterns were categorized into: complete or partial bulk fracture and delamination with or without fracture.
Results: SBS testing concluded a statistically significant (p<0.05) difference between adhesion of composite layers of groups OA and DA for both material combinations. Load-bearing capacities (in N ±SD) are shown in Table 1.
Fracture analysis showed more bulk fractures in OA groups, while DA groups showed predominantly delamination fractures.
Conclusions: It was found that with good interfacial-adhesion, everX Posterior demonstrated high load-bearing capacity even with thin occlusal-surface composite. Deterioration of the adhesion rendered load-bearing capacity more sensitive to the occlusal-layer thickness.
Methods: A total of 120 cylindrical specimens of bi-layered structure were prepared. Three different occlusal-thicknesses (1, 1.5 and 2mm) were fabricated using hybrid-type composite GænialPosterior (GP) and placed on base composites of everXPosterior (EXP) and SDR (total height:5mm). Adhesion between the layers was based on either an O2-inbited layer for optimal-adhesion (OA) or a polished surface for deteriorated-adhesion (DA). Adhesion of the layers was confirmed by debonding test (“shear-bond-strength-test”, SBS). The specimens (n=10) were light-polymerized before static-loading with a steel ball (Ø 4.0mm) until fracture. Fracture patterns were categorized into: complete or partial bulk fracture and delamination with or without fracture.
Results: SBS testing concluded a statistically significant (p<0.05) difference between adhesion of composite layers of groups OA and DA for both material combinations. Load-bearing capacities (in N ±SD) are shown in Table 1.
Fracture analysis showed more bulk fractures in OA groups, while DA groups showed predominantly delamination fractures.
Conclusions: It was found that with good interfacial-adhesion, everX Posterior demonstrated high load-bearing capacity even with thin occlusal-surface composite. Deterioration of the adhesion rendered load-bearing capacity more sensitive to the occlusal-layer thickness.
