Evaluation and management of exposed high-density porous polyethylene implants: an experimental study

Numerous autogenous and alloplastic materials have been used for restoration of contour deformities of the face. Alloplastic materials have come into use to replace autogeneous bone grafts because bone grafts are associated with donor site morbidity, resorption and difficulty in shaping. Porous high-density polyethylene (HDPPE) is a commercial product which is nonallergenic, nonantigenic, noncarcinogenic and nonresorbable, highly stable and somewhat flexible. It has pores of 125-250 mum which enable tissue ingrowth resulting in firm attachment and integration of the implant to the surrounding tissues. In this study we aimed to evaluate the fate of the exposed implants and proposed a method to manage the exposed medpor implants. Twenty rats were used for this experimental study. Three phases involving the implantation, exposition, and the closure of the implants were held respectively. Closure was performed in two groups: 1) After perforating the exposed implants; 2) Without perforating the exposed implants. No serious complications were seen. Perforated exposed implants when covered with flaps rather than grafts could be covered. Exposed implants were not covered easily as indicated by the previous studies. This study demonstrates that early closure of perforated implants with flaps can give the best clinical results when exposed implants are covered in a short period after exposition so that the ingrown fibrous tissues are still intact. We believe that grafting of the exposed medpor implants cannot be effective either in early or late period. Perforating the exposed implants yield successful results as ingrowth of the tissues are enabled.