Background: To improve the ability to prognosticate the final surgery outcomes, this study was carried out to explore the correlation between the number of motor axons given to cross-facial nerve grafts for smile restoration and the aesthetic and functional outcomes.
Methods: Sixty-nine cases had adequate nerve biopsy specimens and were selected for the authors’ study. Patient information was collected from chart review. Using Terzis’ evaluation scale, smile functional and aesthetic outcomes as depicted in standardized videos were graded by a panel of four independent reviewers. Digital images of nerve specimens in stages I and II were obtained by using a microscope with a digital camera attachment. Using MetaMorph software, the number of motor axons was calculated, with the exception of the nerve specimens at the distal nerve grafts in stage II, which were quantitated manually. Mann-Whitney and Fisher’s exact tests were used to test the effects of axon numbers and other factors on the outcomes.
Results: The donor axonal input correlated with the axon number at the distal end of the nerve graft and also correlated with the improvement of evaluation; however, no significance was found between the counts at the distal end of the nerve graft and the clinical outcomes. An important observation was that patients with a donor nerve count of 900 or higher showed a greater likelihood of achieving satisfactory results.
Conclusion: The axon count at the donor nerve has a stronger influence on the final results.