Normal human impacted third molars were collected from adults (19–29 years of age). The crowns of immature human premolars extracted for orthodontic reasons in 12- to 14- year old patients were sectioned, the dental pulps were carefully removed without touching the predentin. Decoronation of tooth was done to standardize the length to 12 mm. Teeth were cleaned and disinfected with ethylic alcohol and thoroughly washed with PBS. Roots were stabilized vertically on inverted transwell inserts in such a way that only the apical third of the root was immersed in cell culture medium. Dental pulp stem cells (DPSC’s) were suspended in 50 μL ofHyStem® Cell Culture Scaffold, in hydroxyapatite scaffold and in collagen scaffold respectively and injected into the roots of human premolars (n = 24 teeth/experimental condition). After 7 to 28 days, DPSC’s were removed from the root canals, and RNA purification, amplification, and RT-PCR for DMP-I, DSPP, and MEPE were performed.