Microphotographs of periodontal tissue on compression side (100×): (A) Control group on day 7. (B) Group B on day 7. (C) Group C on day 7. (D) Control group on day 14. (E) Group B on day 14. (F) Group C on day 14. (G) Control group on day 21. (H) Group B on day 21. (I) Group C on day 21. Arrows mean the direction of bone resorption. The compressed PDL in the Corticision group contained less hyalinized tissue and more viable cells than the control group, resulting in direct bone resorption. (A–I) Hematoxylin and eosin (H&E) stain. b indicates alveolar bone; p, PDL; r, root; h, hyalinization