Review of Dental Implant Rat Research Models Simulating Osteoporosis or Diabetes

Purpose: Osteoporosis and diabetes are physiologic determinants that affect the process of osseointegration. The demand for dental implants is high in these patients, who have benefited from progress in preclinical research. Osseointegration has been extensively studied in rat models of osteoporosis and diabetes. The aim of this study is to present an assessment of the published data and provide consideration for future studies. Materials and Methods: The present study summarizes information through a systematic review of the literature from 1997 to 2008 available through PUBMED. The authors found 20 and 13 articles that report on osseointegration of implants in osteoporotic and diabetic rats, respectively. The survey was extended to recent publications on relevant aspects related to species, strains, and quality of endpoint data. Results: Differences in experimental variables such as timing of implant insertion, location of implants, or duration of disease prior to implant placement were reported and can be justified based on the experimental questions. Moreover, heterogeneity was further caused by variations in the age of rats and in reporting of the main parameters of osseointegration in the cortical and medullary compartments. Regardless of these differences, the evidence indicates consistently that ovariectomy results in reduced osseointegration, while there is only moderate evidence for impaired osseointegration in diabetic rats. Conclusions: Selection of the appropriate protocol is critical when studying implant osseointegration in rats. This overview highlights the demand for quality endpoint data related to animal numbers, data collection, and the way to establish osseointegration. Because of the differences in research questions, general recommendations for uniform models for osteoporosis and diabetes cannot be made. Keywords: bone regeneration, diabetes, implants, osseointegration, ovariectomy, rat