Fiber-reinforced composite fixed dental prostheses – Studies of the materialsused as ponticsUniversity of Turku, Faculty of Medicine, Institute of Dentistry, Department of BiomaterialsScience, Finnish Doctoral Program in Oral Sciences – FINDOS, Annales UniversitatisTurkuensis, Turku, Finland 2015Fiber-reinforced composites (FRC), a non-metallic biomaterial, represent a suitablealternative in prosthetic dentistry when used as a component of fixed dental prostheses(FDPs). Some drawbacks have been identified in the clinical performance of FRCrestorations, such as delamination of the veneering material and fracture of the pontic.Therefore, the current series of studies were performed to investigate the possibilitiesof enhancing the mechanical and physical properties of FRC FDPs by improving thematerials used as pontics, to then heighten their longevity.Four experiments showed the importance of the pontic design and surface treatment inthe performance of FRC FDPs. In the first, the load-bearing capacities of inlay-retainedFRC FDPs with pontics of various materials and thicknesses were evaluated. Threedifferent pontic materials were assessed with different FRC framework vertical positioning.Thicker pontics showed increased load-bearing capacities, especially ceramic pontics. Asecond study was completed investigating the influence of the chemical conditioning ofthe ridge-lap surface of acrylic resin denture teeth on their bonding to a composite resin.Increased shear bond strength demonstrated the positive influence of the pretreatmentof the acrylic surfaces, indicating dissolution of the denture surfaces, and suggestingpotential penetration of the monomer systems into the surface of denture teeth.A third study analyzed the penetration depth of different monomer systems on the acrylicresin denture teeth surfaces. The possibility of establishing a durable bond betweenacrylic pontics and FRC frameworks was demonstrated by the ability of monomers topenetrate the surface of acrylic resin denture teeth, measured by a confocal scanningtype microscope. A fourth study was designed to evaluate the load-bearing capacities ofFRC FDPs using the findings of the previous three studies. In this case, the performanceof pre-shaped acrylic resin denture teeth used as pontics with different compositeresins as filling materials was evaluated. The filling material influenced the load-bearingcapacities, providing more durable FRC FDPs.It can be concluded that the mechanical and physical properties of FRC FDPs can beimproved as has been shown in the development of this thesis. The improvementsreported then might provide long lasting prosthetic solutions of this kind, positioningthem as potentially permanent rehabilitation treatments.Key words: fiber-reinforced composite, fixed dental prostheses, inlay-retained bridges,adhesion, acrylic resin denture teeth, dental material.
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