Fig. 3

Premolars teeth treated with RAP or CH at 6 months. a Apical root area of a premolar tooth treated by CH after 6 months showing bridging of the apical foramen (AB). Granulation tissue (GT) surrounds and is observed at a distance from the regenerated root dentin. Root canal (RC). H & E stain. Original magnification, × 100. b Apical root area of a premolar tooth treated by CH after 6 months showing bridging of the apical foramen (AB). No immuno-reactivity to Wnt10bantibody is observed. Bone (B), granulation tissue (GT), root canal (RC). Original magnification, × 100. c Apical root area of a premolar tooth treated by CH after 6 months showing bridging of the apical foramen (AB) by calcified material and cellular cementum (CC). The root canal (RC) shows some calcified material in the apical root canal bony islands (BIs) (box), granulation tissue (GT). H&E stain. Original magnification, × 100. d Apical root area of a premolar tooth treated by RAP at 6 months showing bridging of root apex (AB) by cellular calcified material. Granulation tissue (GT) root canal (RC). H&E stain. Original magnification, × 100. e Apical root area of a premolar tooth treated by RAP at 6 months showing mild to moderate immunodetection of Wnt10b throughout the newly formed apical bridge (AB) and periodontal ligament (PDL). Root canal (RC). Wnt10b antibody. Original magnification, × 200. f Apical root area of a premolar tooth treated by RAP at 6-months showing apical bridging (AB) by a continuous layer of dentin (D) at the root apex. The newly formed dentin is attached to regenerated bone (B) by cementum (arrow) and periodontal ligament (PDL). Bone (B), root canal (RC). Trichrome stain. Original magnification, × 100. g Apical root area of a premolar tooth treated by RAP at 6 months showing bridging of root apex (AB) by cellular calcified material. Dentin (D), periodontal ligament (PDL) root canal (RC). H&E stain. Original magnification, × 200. h Apical root area of a premolar tooth root treated by RAP at 6-months showing bridging of the root apex (AB). Intense immunodetection of nestin antibody (Nesin) is observed in the newly formed apical bridge, odontoblast cell layer (od), in periodontal ligament (PDL) and in incremental lines in the tertiary dentin of the newly formed bridge (arrow). Regenerated bone (B) surrounds the regenerated root dentin. Root canal (RC). Wnt 10b antibody. Original magnification, × 100. i Apical root area of a premolar tooth root treated by RAP at 6 months showing the opened apex being bridged (AB) by cellular calcified tissue that extends into the root canal (arrow). The newly formed bridge is attached to regenerated bone (B) cementum (C) and periodontal ligament (PDL). Dentin (D) and Root canal (RC). Trichrome stain. Original magnification, × 100