Results of ongoing studies substantiate the working hypothesis that the bone ingrowth into a porous polymeric coating on artificial tooth roots can serve as the attachment vehicle for free-standing endosseous dental implants. Furthermore, the results have demonstrated that mechanical property requirements of this type of dental implant system are not met by porous high density polyethylene, but are met by porous polysulfone.
The specific aims are now to: 1) quantitively evaluate histological changes with time in bone and gingiva around clinically successful porous polysulfone-coated artificial tooth roots through five years of implantation, 2) construct a survival curve for this implant serving as a free-standing mandibular, posterior tooth in occlusion, and 3) determine the load-carrying capacity of the artificial tooth roots three months and two years after implantation. The Rhesus monkey is the experimental animal model. Porous polysulfone-coated artificial tooth roots of the type presently being investigated will be implanted in healed, mandibular premolar extraction sites in Rhesus monkeys. Each animal will receive two implants. In a first series of animals five implants will be retrieved by block resection after each of the following time periods: 1, 3, 6, 12, and 24 months after placement of transgingival abutments to the submucosal roots. Five other implants will be retrieved at the submucosal stage prior to placement of the implants in function. This totals 30 implants retrieved from 15 animals. A second series of eight implants will be mechanically tested to determine the load-carrying capability of the implants 3 and 24 months after placement of the transgingival abutments. Finally, a group of six monkeys will be continued from the ongoing study to eventually yield implants of five-years duration. Histomorphometric analyses will be performed on undecalcified microtome sections using a semi-automated image anaalysis system. Survival analysis of the """"""""censored data"""""""" will be performed to generate a survival curve and to determine the """"""""time-to-failure"""""""". A correlation of the histology, mechanical test data, and the survival data will be made.
