Effect of metformin on oral implant healing in diabetic rats

Methods: Thirty-two twelve week old male rats were assigned to three groups of twelve each: the control (CTL) group consisted of non-diabetic Wistar-Kyoto rats; the GK group consisted of Goto-Kakizaki (GK) rats, who spontaneously became mildly hyperglycemic with type 2 diabetes mellitus (blood glucose >250mg/dl) ; and lastly, the GKM group consisted of GK rats fed metformin (100 mg/kg body weight/ day, Sigma-Aldrich) ad libitum in their drinking water. All right maxillary first molars were removed and the extraction sites were allowed to heal for four weeks. Titanium implants (1 x 3mm bone screws, Stryker) were placed in the healed region of the maxillary first molar extraction. Six rats in each group were sacrificed at weeks 1 and 4 and their maxillae containing the implants were analyzed by microCT.

Results: At week 1, the bone to implant contact ratios of metformin-fed diabetic rats were similar to non-diabetic rats, with both groups showing more bone to implant contact than the uncontrolled diabetic animals. At week 4, the metformin-fed diabetic animals had no trace of metformin in their blood and subsequently showed a bone to implant contact ratio similar to the uncontrolled diabetic animals. However, the non-diabetic animals maintained a higher bone to implant contact ratio than either the diabetic GK rats or metformin-fed GK rat groups.

Conclusion: This study, in our oral implant rat model, suggests that metformin improves peri-implant healing in type 2 diabetes.

Funding provided by U.S. Army Fort Gordon Dental Activities