Effects of material porosity on implant bonding strength in a craniofacial model.

Alloplastic craniofacial implantation is a developing surgical option. Several alloplastic materials are available with a porous feature. While porosity may permit bone ingrowth, it is unclear whether it offers improved implant fixation over that of nonporous bone substitutes in the craniofacial skeleton. Bilateral mandibular ramus defects were created and reconstructed with porous and nonporous block implants in the mature rabbit. At 3, 6, and 12 months postoperatively, the mandibles were removed and prepared so that only the bone-implant interface connected the proximal and distal segments. The anterior mandible was then loaded to destruction. The fatigue load (in kg) for each implant was obtained and statistically compared. Significant differences in fatigue loads between the implant types occurred at all postoperative periods with the porous block material consistently exhibiting the greater resistance to separation. Resistance to fatigue fracturing for either implant type did not increase after the sixth postoperative month.