(52) Optimizing a murine implant model

Introduction: Dental implants are increasing in prevalence as desirable options in replacement of missing teeth. Unfortunately, implants come with complications, and animal models are key to studying the pathophysiology of complications, such as peri-implantitis. Current murine models are limited and involve unilateral tooth extraction, thus not allowing for split-mouth design. These experiments can be lengthy in time with eight weeks of extraction socket healing prior to implant placement. Therefore, our objective was to investigate the efficacy of decreasing extraction healing time from eight to four weeks and to test a bilateral extraction/implant placement model in mice.

Methods: Forty-six three-week-old C57BL/6J male mice underwent maxillary first and second molar extractions. Exp-1: Unilateral extraction of left maxillary molars followed by eight (control) or four (test) weeks of extraction socket healing prior to implant placement. Exp-2: Unilateral (control) or bilateral (test) extractions with implant placement four weeks after extraction socket healing. Four weeks after implant osseointegration, mice were sacrificed. Implant osseointegration was analyzed clinically. Linear measurements, from base of implant head to alveolar bone crest, were performed to evaluate implant positioning and initial bone crest remodeling via micro-CT. Percent bone volume surrounding the implants (bone volume/tissue volume) was analyzed via micro-CT.

Results: When mice received implants four weeks following extractions, there was no statistical difference in initial bone crest remodeling or surrounding bone volume compared to those that received implants after eight weeks of extraction socket healing. When comparing the same metrics for the unilateral and bilateral groups both with four weeks of extraction socket healing, there was no statistical difference. Within the group that received bilateral implants, there was no statistical difference between the right and left implants in initial bone crest remodeling, implant osseointegration, or surrounding bone volume.

Conclusions: The use of a four-week extraction healing period is similar to eight weeks. The bilateral implant mouse model is an effective alternative to the unilateral model. The advantages of placing implants four weeks after extractions and utilizing a bilateral model include better control method (split-mouth design), fewer animals, decreased experimental time, and decreased cost.

Lead Author's Contributions to the Research Project. : Lead author assisted during extraction, implant placement, and sacrifice procedures. Lead author was responsible for micro-CT processing, data acquisition and analysis, as well as composition of the abstract.