Growing concerns on use of metallic implants for bone fracture fixation of bone and associated stress-shielding, with subsequent resorption, have led the orthopedic community to explore carbon fiber-reinforced, high-performance engineering thermoplastics (PEEK) as a less rigid alternative to metals. Unreinforced PEEK was not considered a suitable metal substitute for its relatively very low modulus. Although well addressed in orthopedics, the use of this technology in dental implants is scarce. This, and the availability of novel technologies that are believed to increase viability of PEEK systems as bone and/or dental implants, provided an incentive to pursue the proposed program. The objective of Phase I is to determine feasibility of using highly oriented and carbon fiber-reinforced PEEK as dental implants, which may have a microporous surface that is chemically activated for hydroxyapatite deposition and induced osteointegration. Phase I plans entail ( 1) preparation of highly oriented sheets by solid-state compressive orientation and machining to cylindrical dental implants; (2) preparation of carbon fiber-reinforced PEEK composites and conversion to implantable cylinders; (3) surface modification of dental implants to impart microporosity; (4) activation of microporous and plain surfaces of different cylinders to introduce -C-P(O)(OH)2 groups; (5) completion of an in vitro study on deposition of calcium phosphate onto implant surfaces; (6) placing the implants into goat mandibles for 10 weeks; and (7) evaluating mechanically and histologically bone apposition and interfacial bonding between jaw bone and different implants. Results of Phase I will be used to design Phase II plans, which include (1) developing and scaling-up studies of implant materials; (2) preparing prototypes of a selected form of dental implants; (3) studying the effect of implant surface chemistry on performance in two animal models; (4) initiating safety study with a final prototype; and (5) achieving an IDE.
Successful conversion of PEEK and its components into high modulus, but less rigid alternatives to metals, will have a major impact on the development of non-metallic dental and orthopedic implants. Achieving a phosphonylated microporous PEEK surface in dental implants, which induces osteointegration will represent a key milestone in the use of non-metallic, rigid implants.
| Allan, J M; Wrana, J S; Linden, D E et al. (2000) Bone formation into surface phosphonylated polymeric implants. Crit Rev Biomed Eng 28:377-82 |
