Effects of Flurbiprofen and Orthodontic Stimulation on Osteogenesis in the Rat Mandibular Condyle

Abstract

The effects of flurbiprofen administration and/or mechanical stimulation of the teeth upon osteogenesis in the rat mandibular condyle are unknown. To study this problem, 38 male Sprague Dawley rats, between six-eight weeks old, were divided into four groups as follows: 13 rats each in groups stimulated orthodontically and receiving flurbiprofen or stimulated orthodontically and receiving placebo; six rats each in groups not stimulated orthodontically and receiving flurbiprofen or not stimulated orthodontically and receiving placebo. The rats were given weekly intraperitoneal injections of fluorescent bone labels for three weeks, then elastic separators were placed between the maxillary molars in the appropriate 26 rats. Following elastics placement, the appropriate rats received either an intramuscular injection of 0.1 mg/kg flurbiprofen in 1 :1 ethanol and saline buffer or an equal volume of 1 :1 ethanol and saline alone every seven hours for 35 hours following the placement of elastics. All rats received subcutaneous injections of 0.25 μCi/g. 3H-thymidine every seven hours for 35 hours following elastics placement. The animals were euthanized one hour after the final injections. The condyles of each rat were blindly evaluated using nuclear volume morphometry, autoradiography, and fluorochrome analysis. A two-way analysis of variance was used to evaluate for differences among the groups. A post-hoc Newman-Keul's test was employed where needed. A level of significance of p < 0.05 was used. It was found that the rats given flurbiprofen had a higher 3H-thymidine labelling index than the rats given placebo, suggesting flurbiprofen enhances the rate of osteoblast formation and osteogenesis in the rat mandibular condyle, in the short-term. While it is not known how this short-term increased rate of osteoblast formation would correlate to the amount of bone formation clinically, it may be significant. It is possible the potential stimulation of bone formation by flurbiprofen may be useful in the treatment of patients with periodontal disease. Perhaps this potential stimulation of bone formation may also be beneficial in enhancing the jaw growth of orthodontic patients with jaws deficient in size.