Assessment of microsphere-controlled drug delivery for local control of tooth movement

Abstract

Background: Orthodontics is a special discipline dedicated to the investigation and practice of moving teeth through the bone. This study was conducted to assess new methods to locally enhance orthodontic anchorage. Materials and Methods: A single injection of 1 mg/kg nonencapsulated or microsphere encapsulated osteoprotegerin (OPG) was delivered into the palatal mucosa mesial to the first maxillary molar 1 day prior to tooth movement. A positive control group received injections of 5 mg/kg nonencapsulated OPG every 3 days during tooth movement. After 28 days of tooth movement, hemi-maxillae and femurs were dissected. Molar mesial and incisor distal tooth movement was measured using stone casts that were scanned and magnified. Results: Maximum movement was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG, 1 mg/kg encapsulated OPG, and 5 mg/kg nonencapsulated OPG. Maximum movement 2.6 mm was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG (2.4 mm), 1 mg/kg encapsulated OPG (2.5 mm), and 5 mg/kg nonencapsulated OPG (1.2 mm). A significant difference was found in bone mineral content, bone mineral density, tissue mineral content, and tissue mineral density with encapsulated and encapsulated OPG and microspheres (P < 0.05). Conclusion: Authors found that microsphere encapsulation of OPG allows for controlled drug release and enhances site-specific orthodontic anchorage without systemic side effects.