Sustained Release of Insulin-like Growth Factor-1 from Poly(lactide-co-glycolide) Microspheres Improves Osseointegration of Dental Implants in Type 2 Diabetic Rats

Dental implantation is an effective and predictable treatment modality for replacing missing teeth and repairing maxillofacial defects. However, implants in patients with type 2 diabetes mellitus are likely to have a high failure rate and poor initial osseointegration. In the current study, we established an effective drug delivery system designed to improve osseointegration of dental implants in an animal model of type 2 diabetes. Twenty type 2 diabetic rats were divided into two groups: a group receiving recombinant rat Insulin-like Growth Factor 1 (rrIGF-1) Microsphere Therapy (MST) (10 rats) and a control group (10 rats). The rrIGF-1 was encapsulated into poly(lactide-co-glycolide) (PLGA) microspheres to produce a sustained-release effect around titanium (Ti) dental implants in the rrIGF-1 MST group. Scanning electron microscopy, confocal laser scanning microscopy, and cumulative-release studies were conducted to verify the release effect of the microspheres as well as rrIGF-1 bioactivity. Five rats from each group were sacrificed at weeks 4 and 8 post surgery, and a histological analysis was performed on the rats from both groups. Compared to the control group, rats that received rrIGF-1 by PLGA microsphere treatment were observed to have a higher bone-implant contact percentage around the Ti implants at week 4 or week 8 post surgery (P<0.05). This result clearly indicates that sustained release of rrIGF-1 through encapsulation by PLGA microspheres positively affects osseointegration of dental implants in type 2 diabetic rats.