【Objective】 Recently, orthodontic anchor screws have been widely used as anchorage units in orthodontic treatment. However, there are some disadvantages include dropout during treatment and the invasiveness of screw removal. The objective of this study was to develop an orthodontic anchor screw in which the main component is a bioabsorbable material consisting of polyglycolic acid (PGA) and hydroxyapatite (HAp).
【Methods】 The composites of PGA/HAp included five types with a HAp compound ratio by weight of 0%, 5%, 10%, 30% and 50% respectively. Real-time PCR and ELISA were used to assess the effects of the PGA/HAp components on the gene and protein expression levels of osteocalcin (OC) and type I collagen (COL-I) in mouse osteoblasts (MC3T3-E1) in vitro. Furthermore, in order to evaluate the osteoinductive potential in vivo, the calvarial defect of rats was evaluated after placing the sample by μ-CT image analysis.
【Results】 The production of COL-I reached a peak on day 7 and increased depending on the HAp concentration. Additionally, that of OC increased in a dose- and time dependent manner up to day 10. In the in vivo study, μ-CT image analyses showed that newly formed bone areas in defects for PGA/HAp disk were significantly higher than those for sham operation (controls) two and three months after surgery.
【Conclusions】 The current results suggest that the biological properties of our PGA-based trial prototype are increased by mixing with HAp. An orthodontic anchor screw based-PGA tool may be useful for orthodontists.