The Comparison On Microtensile Bond Strengths Of Three Composite Resin Core Materials To Glass Fiber Posts

With the development of oral prosthodontics, fiber post and resin core systems are applied more and more widely in the restoration of residual roots. The restorative materials are gradually transferred from traditional rigid materials (eg. amalgam, gold alloy) to composite resin or fiber composite materials whose biomechanical properties are more close to dentin (eg. Fiber post). Whether the restoration is successful depends on not only high bond strength between fiver post and resin, but also enough mechanical strength of core materials to withstand functional stress loads in oral cavity. These properties are closely associated with the type and properties of composite resin core materials.There are various core materials for clinical application at present, including resin composite for core buildup and universal composite resin. Their different compositions and properties resulted in different properties of core materials and their bond strengths to fiber posts. In this thesis, mechanical strengths of three core resin materials were tested, the bond strength of three core resins to fiber post were investigated; and the fracture resistance of three core resin- fiber post systems were evaluated in in vitro model. We aimed to make comprehensive evaluation of three commonly used core resin materials through the studies, to provide references for the selection of resin core materials in clinic.The main resuls are as follows:1. DC Core Automix showed the highest mechanical strength among the three resin core materials, followed by Luxa Core.Charisma presented the lowest mechnical strength.2. DC Core Automix exhibited significantly higher micro-tensile bond strength to DT Light glass fiber posts than Luxa Core and Charisma.3. The fracture patterns of the adhesive interface bwteen three resin core materials and fiber posts were not significantly different. Adhesie failure is the main fracture pattern among all the groups.4. The fracture resistance of DC Core Automix was the highest among the three recin core materials. The lowest fracture resistance of all the samples was 34.4±1.4 kg, which was higher than the upper limit of the range of normal occlusal force (30 kg). They were strong enough for clinical application. The fracture patterns of three core materials were significantly different. Among them, DC Core Automix and LuxaCore presented mostly the fracture of core, while separation of post and root were observed mostly in Charisma post-core system.