Effect Of The Various Implant Placement And Loading Protocols On The Regeneration Of Peri-implant Nerve Fibers

Purpose:The aim of this experiment was to disclose the effects of different implant placement and loading protocols on the regeneration of peri-implant nerve fibers,including the number of the never fibers of different parts around the implant and their changes over time.Materials and Methods:10 beagle dogs,aged 12-24 months,were included in this experiment.68 dental implants were inserted on both sides of the lower jaw,which were separately the second premolar,the third premolar,the fourth premolar and the first molar,according to the different protocols including eight various ways of implanting and loading respectively are immediate implant and immediate loading for3 months(IIP+IL3)or 6 months(IIP+IL6)and unloading(IIP+UL),immediate implant and delayed loading for 3 months(IIP+DL3)or 6 months(IIP+DL6),delayed implant and immediate loading for 3 months(DIP+IL3)or delayed loading for 3months(DIP+DL3),unloading(DIP+UL)and the natural teeth group(control group).All of the dogs were sacrificed 9 months later and specimens were prepared for histological.Result:Six of these sets failed and four out six were from the IIP+DL3 group and each of the other two was from the IIP+DL6 group and the DIP+DL3 group respectively.62 spacemen were included in the experiment.Immunocytochemistry and transmission electron microscopy were used to confirmed the presence of neural structures and to reveal their ultrastructural characteristics,respectively.Myelinated nerve fibers densely populated the peri-implant crestal gingival and apical regions,although they were also identified in the woven bone and in the osteons near the implant treads.To compare three regions we chose in each group,the apical region has higher nerve number around the implant than the other regions in all the groups,especially in the IIP+IL6,the IIP+DL6 and IIP+UL group,the differences between the coronal region and apical region are statistically significant.Compared the different implant protocols,the difference between IIP+IL3 group and IIP+DL3 group in coronal region(in N/mm~2,23±3.6 vs.10.7±1.5,P=0.0493)and in the apical region(in N/mm~2,37±10.1 vs.19±5.5,P=0.0055)are statistically significant.Conclusion:It may be assumed that the treatment protocol with IIP+IL is the preferred method to allow optimized peri-implant re-innervation,but further functional measurements are still required.