Figure 1.

The experimental model and clinical parameters. Overview of the study schedule (a). C (no intervention), PD (ligature-induced periodontitis), G1 (ligature-induced periodontitis plus once-daily administration of CLH gel), G3 (ligature-induced periodontitis plus a thrice-daily administration of CLH gel). Average periodontal attachment loss (the distance between the cemento-enamel junction (CEJ) and the coronal position of the junctional epithelium) in the first molar (b). Results represent the means ± standard error of the mean (SEM) performed in four samples. H&E staining of the interdental epithelial attachment (black arrows indicate the actual epithelial attachment) between the first and second molars at low and high magnifications (c). Results represent the means ± SEM performed in four samples in each group. Clinical measurements of the PPD (distance from the gingival margin to the pocket bottom) at three sites (mesial, medial, distal) on the buccal side of the first molar (d). Results represent the means ± SEM of 10 samples. Immunohistochemical analysis of collagen fibers at low and high magnifications (e). Results represent the means ± SEM of collagen fibers of four samples in each group (f). Statistical analysis was performed with one-way ANOVA. ns, no significance. * p < 0.05; ** p < 0.01; **** p < 0.0001.