Objective:Tostudytheeffectofnervegrowthfactor(NGF)andSchwanncellsonaxonregenerationoftheinferioralveolarnervefollowingmandibularlengtheningwithdistractionosteogenesis.Methods:Unilateralmandibularosteodistractionwasperformedin9healthyadultmalegoatswithadistractionrateof1mm/d.Every3goatswerekilledondays7,14and28aftermandibularlengthening,respectively.TheinferioralveolarnervesinthedistractioncalluswereharvestedandprocessedforultrastructuralandNGFimmunohistochemicalstudy.Theinferioralveolarnervesfromthecontralateralsidewereusedascontrols.Results:Onday7afterdistraction,axondegenerationandSchwanncellproliferationwereobserved,andverystrongstainingofNGFinthedistractednervewasdetected.Onday14afterdistraction,axonregenerationandremyelinationwereeasilyobserved,andNGFexpressionstartedtodecline.Onday28afterdistraction,thegrayscaleofNGFimmunoreactivityrecoveredtothenormalvalueandtheSchwanncellsalmostrecoveredtotheirnormalstate.Conclusions:Gradualmandibularosteodistractioncanresultinmildormoderateaxondegenerationoftheinferioralveolarnerve.NervetraumamaystimulatetheproliferationofSchwanncellsandpromotethesynthesisandsecretionofNGFintheSchwanncells.SchwanncellsandNGFmightplayimportantrolesinaxonregenerationoftheinjuredinferioralveolarnervefollowingmandibularlengthening.
