Fig. 1

Clinical manifestation of periodontitis and radiographic assessment of bone loss. a Intraoral photograph of the ligated second upper molar in a rat with arthritis and experimental periodontitis. b Radiograph image of bone volume around a second upper molar, c micro-CT data (horizontal section) indicating bone loss around the upper molars and d, e 3D rendering of micro-CT data of bone volume around maxillary molars in an arthritis rat with experimental periodontitis. f Intraoral photograph of the non-ligated second upper molar of an arthritis rat without induced periodontitis. g Radiograph image of bone volume around the second upper molar, h micro-CT data (horizontal section) indicating bone loss around the upper molars and i 3D rendering of micro-CT data of bone volume around maxillary molars in a rat without induced periodontitis. j Mean tooth mobility score (±SE) in arthritis rats with periodontitis (n = 9) and without periodontitis (n = 12) throughout the experimental period of 15 weeks. k Distribution of mean alveolar bone level at endpoint in arthritis rats with periodontitis (n = 8) and without periodontitis (n = 10). ^*P < 0.05 was considered statistically significant. Circle indicates outliers. Gray line indicates time point of pristane injection. PIA pristane-induced arthritis, PA rats with experimental periodontitis and PIA, A rats with PIA without periodontitis