Histomorphometric Study of Peri-Implant Bone Healing in the Case of Nerve Injury: An Experimental Model in Rats

Causes of dental implant failure are of more than passing interest. Within the group of failures caused by iatrogenic factors, injury to the epineurium has been reported to cause the formation of peri-implant fibrous tissue (fibrointegration). The aim of this study was to perform a histomorphometric evaluation of the percentage of osseointegration of implants in contact with the epineurium. Twenty Wistar rats were used. The first lower molars were extracted under xylazine-ketamine anesthesia. A titanium screw implant (diameter, 0.75 mm; length, 2.26 mm) was placed. In the control group (n = 10), apical anchorage of the implant was performed. In the experimental group (n = 10), the apical portion of the implant was placed in contact with the epineurium of the lower mandibular nerve. All animals were killed by ether overdose 30 days after implantation. Radiographs were taken, and the samples were processed for embedding in acrylic resin. Ground sections were obtained along the vestibulo-lingual axis of the mesial alveolus that contained the implant and were stained with toluidine blue. The histologic analysis revealed the presence of bone tissue in the apical portion of the control group samples. In the experimental group, the implant was in contact with the epineurium. There were no statistically significant differences in the percentage of osseointegration between both groups (control group, 39% +/- 9%; experimental group, 38% +/- 10%). The results obtained with this experimental model show that the contact of the implant with the epineurium would not impair the process of osseointegration.