Research Paper Volume 15, Issue 5 pp 1279—1305

Figure 1. Analysis of periodontal tissue in aged mice. (A) Micro CT (μCT) analysis of alveolar bone in the upper jaw. Representative images of young (6-week-old) and aged (68~104 weeks-old) mice are shown. Scale bar = 1 mm. Quantification of the bone resorption rate in supportive alveolar bone was evaluated. Distance between the cement–enamel junction to the crest of alveolars bone at the a, mesial root at first molars, b, distal root at first molars, and c, mesial root at second molars. Box-and-whiskers plots shows median, 25th and 75th percentile with whiskers at the 5th and 95th percentile. Young mice; n = 7, aged mice; n = 11 Statistical analysis was completed using welch’s t-test, with p-values < 0.05 were considered statistically significant (^*p < 0.01, ^#p < 0.05). (B) X-gal staining of frozen sections of periodontal tissue of the mesial root at first molars in the upper jaw. (×40) White arrows indicate SA-β-gal positive cells. Scale bar = 500 μm. Right panels show the enlarged image of the bold square in the left panel (×100). Scale bar = 100 μm. Abbreviations: D: Dentin; PD: Periodontal ligament; AB: Alveolar Bone. Representative data from three experiments are shown. Right graph shows the percentage of SA-β-gal positive cells in PDL of young or aged mice (^*p < 0.01). (C) Representative immunohistochemistry images of p16, lamin A/C, and SIRT1 (40×). Scale bar = 200 μm. Abbreviations: D: dentin; PD: periodontal ligament; AB: alveolar Bone. Yellow arrow: antibody-positive cells (40×). Representative data from three experiments are shown. Lower graph shows percentages of antibody-positive cells in PDL area of young or aged mice (^*p < 0.01). (D) Expression of p16, p21, and IL-6 in PDL tissue of young (6~13-weeks-old, n = 7) and aged (68~104-weeks-old, n = 6) mice. Expression of p16, p21, and IL-6 mRNA in PDL derived from freshly isolated mouse teeth was analyzed by qRT-PCR (^#p < 0.05). Representative data from three experiments are shown.