Low-dose doxycycline inhibits bone resorption associated with apical periodontitis

Metzger Z, Belkin D, Kariv N, Dotan M, Kfir A. Low-dose doxycycline inhibits bone resorption associated with apical periodontitis. International Endodontic Journal, 41, 303-309, 2008.AbstractAim To test the effect of low-dose doxycycline on bone resorption associated with apical periodontitis. Methodology Apical periodontitis was induced by occlusal pulp exposure in the mandibular first molars of 36 rats. Animals were divided into three groups of 12: group A received doxycycline in drinking water at a dose of 5.85 mg day ^-1; group B received a dose of 1.48 mg day^-1 (one-quarter of the original dose); and group C received no medicament and served as the control. A bioassay determined the doxycycline serum levels. After 21 days, the mandibles were removed, radiographed and the radiographs scanned to generate digital images. These images were analysed morphometrically and the total area of the periapical bone resorption of the mesial and distal roots of each tooth was determined and used to compare the groups. Statistical analysis was completed using anova with repeated measures. Results The mean doxycycline serum level in group A was 0.22(±0.03) g mL^-1 and in group B below the detection level of the assay (<0.062 g mL^-1). The mean area of the periapical bone resorption in the control group C was 2.91(±0.61) mm². In animals treated with a low-dose doxycycline, the mean size of the bone resorption was significantly smaller at 1.59(±0.59) mm ² (group A) and 1.72(±0.85) mm² (group B) (P = 0.001). No significant difference was found in the area of the bone resorption between these two groups A and B. Conclusions Low-dose doxycycline reduced the area of bone resorption associated with apical periodontitis in the mandibular first molar teeth of rats.