This application for a K23 award is based upon this candidate's tong-term goal to design and conduct clinical research and develop new dental biomaterials for clinical use. The candidate is board qualified in two clinical dental specialties, Prosthodontics and Periodontics. As a resident and faculty member, he has had opportunities to work with knowledgeable researchers who have guided his efforts in patient-based research. The candidate has developed a good understanding of scientific method and a solid foundation of skills, but seeks to further his research skills to gain independence and more effectively collaborate with biomaterials researchers and biostatisticians. A mentored training program which includes specific areas of didactic training in areas such as clinical research methodology, data management, biostatistics and polymer composite science will allow the candidate to accomplish these goals. The focus of this candidate's research in recent years has been fiber-reinforced composite (FRC) research. The candidate has been involved in developing FRC materials, devising techniques for their use in making dental prostheses and testing these materials and techniques in the laboratory and the clinic. This proposal is designed to provide a clinics test for FRC prostheses used for implant dentistry. Glass FRC materials have been developed which have the potential to make an esthetic dental implant prosthesis substructure without the potential for corrosion and toxicity which may be seen with commonly used metal alloys. Laboratory and clinical research evaluating FRC prostheses used to restore and replace teeth has shown that these materials exhibit excellent mechanical properties and can form a chemical bond to polymer-based veneer materials. Two different designs of FRC implant prostheses have recently been developed: 1) Screw-retained, retrievable prostheses and 2) Luted, non-retrievable prostheses. There is an important need for these two designs to be tested to determine if either is clinically superior. The candidate for this K23 award proposes to make an intra subject comparison between these two types of FRC partial implant prosthesis. The primary comparison between these prosthesis designs will be the incidence of Outcomes Requiring Intervention (failure of prosthesis or non-failures requiring intervention) observed over three years of recall examination.