INTRODUCTION: The loss of dental pulp may weaken teeth, rendering them 
susceptible to reinfection, fracture, and subsequent tooth loss. Therefore, 
regeneration of pulp is considered an ideal treatment to preserve teeth. The aim 
of this study was to explore the capacity of dental pulp stem cells (DPSCs) and 
platelet-rich plasma (PRP) to regenerate dental pulp in canine mature permanent 
teeth.
METHODS: Pulpectomy with apical foramen enlarged to a #80 file was performed in 
16 upper premolars of 4 beagle dogs. Four experimental groups were randomly 
established: (1) the blood clot group, (2) the autologous DPSCs group, (3) the 
PRP group, and (4) the DP + PRP group (a mixture of DPSCs and PRP). Four lower 
premolars without any further treatment after pulpectomy were used as the 
control group. All teeth were sealed with mineral trioxide aggregate and 
composite. Twelve weeks after transplantation, the teeth were subjected to 
radiographic and histologic examination.
RESULTS: Twenty-four of 32 experimental root canals gained newly formed tissues. 
All canals with an introduction of a blood clot showed histologic evidence of 
vital tissue formation. Cementum-like and periodontal ligament-like tissues 
along the internal root canal walls were typical structures in most cases. There 
is no significant difference between groups with or without autologous DPSC 
transplantation (exact chi-square test, P < .05).
CONCLUSIONS: New vital tissues can be regenerated in permanent canine teeth 
after pulpectomy and enlargement of the apical foramen. Histologically, 
transplantation of DPSCs and/or PRP into root canals showed no enhancement in 
new tissue formation compared with inducement of a blood clot into the root 
canals alone.