Expanded polytetrafluoroethylene entubulation of the rabbit inferior alveolar nerve

Objective. The purpose of this study was to evaluate the use of an expanded polytetrafluoroethylene conduit in the treatment of a 6.0-mm gap in the ra bbit inferior alveolar nerve and compare the results with those of an autog enous interpositional tibial nerve graft. Study design. The inferior alveolar nerves of 5 adult New Zealand White fem ale rabbits (10 nerves) were exposed bilaterally, and a 6-mm segment of eac h nerve was resected. On one side, chosen at random, the gap was immediatel y bridged through use of an 8.0 x 2.0-mm expanded polytetrafluoroethylene c onduit; on the other side, the gap was grafted with an autogenous tibial ne rve graft. Two randomly selected nerves served as sham-dissected controls. At 15 weeks after surgery, the animals were killed and the entire nerve seg ments were harvested and prepared according to standard fixation and embedd ing techniques. The sections were examined histomorphometrically to quantif y the degree of axonal regeneration through definition of fascicular number , total fascicular surface area, axonal density, and mean axonal diameter a t 3 locations along the repair site. Results. Light microscopic examination revealed the presence of disorganize d neural tissue in both groups, with slightly more fibrovascular interfasci cular tissue in the expanded polytetrafluoroethylene group. Histomorphometr ic analysis revealed no significant differences between groups for most of the measured variables. The mean axonal diameter varied between groups, and the fascicular number was greater in the expanded polytetrafluoroethylene group at the middle site. Conclusions. This study demonstrates that regeneration of the inferior alve olar nerve can occur across a 6.0-mm gap through an expanded polytetrafluor oethylene tube with results comparable to those of an autogenous nerve graf t, significant donor site morbidity being avoided. The significant differen ces between groups were probably due to greater containment of regenerating axonal fibers in the expanded polytetrafluoroethylene group.