Injectable simvastatin in periodontal defects and alveolar ridges: Pilot studies

Background: Topical injection of simvastatin in methylcellulose gel was shown to stimulate bone growth and inflammation over mouse calvaria and in rat mandible models. The purpose of these pilot studies was to evaluate the potential of locally injected simvastatin in human-sized periodontal defects. Methods: Chronic periodontal defects were created bilaterally in seven 1-year-old beagle dogs: 3-walled intrabony defects distal of the mandibular second premolar and mesial of the fourth premolar and Class II furcation defects at the buccal furcation of the mandibular first molars. The edentulous space distal to the mandibular canine was left undisturbed. After 16 weeks of healing, defect sites were treated with scaling and root planing, and mandible sides were randomly selected to receive three weekly injections of 0.5 mg simvastatin in 30 mu l methylcellulose gel and contralateral gel alone (n = 3) or 2.0 mg simvastatin/methylcellulose gel and contralateral gel alone (n = 4). Two months following drug application, block sections, including teeth and surrounding tissues, and submandibular lymph nodes were obtained for histomorphometric analysis. Results: Two trends were noted in this pilot study: buccal edentulous ridge thickness was 29% greater with simvastatin, 0.5 mg, compared to gel alone (P= 0.0845), and the simvastatin groups had bone-height loss in interproximal intrabony and furcation defects, but the length of new cementum in the interproximal intrabony defects was greater with simvastatin, 0.5 mg (035 +/- 0.14 mm), compared to gel alone (0.06 +/- 0.15 mm; P= 0.069). No new cementum was found in furcations. Conclusions: Multiple injections of simvastatin are not appropriate for the treatment of intrabony or furcation defects. However, this approach shows potential to augment bone thickness in closed alveolar environments.