Methods: There were 5 immature non-vital teeth with apical periodontitis in this research. After doing the radiographic and clinical testing and access cavity preparation, the pulp champers were irrigated with copious amount of 0.5% hypochlorite followed by 10 cc normal saline. The three mixed antibiotic were then placed in pulp champers and the teeth were temporary restored. After two weeks the teeth were mechanically irritated to bleeding with a large file to bleeding and the activated PRP with cacl2 which was extracted from the own penitents, were rinsed to the pulp chambers to form the blood clot and teeth were temporarily restored again. Two weeks later considering no sign and symptoms a double sealed crown filling were placed on the teeth and the 3, 6, and 9-month follow-ups were done in all patients.
Results: In the first 3-month follow-up in all cases increase of the dentinal walls thickness and closing the apex in at least one case was observed. In the 6-month follow-up increasing the dentinal walls thickness in one case and closing all the other apexes were reported and in the 9-month follow-up continuing the increasing of the dentinal walls thickness were mentioned.
Conclusions: The results of this in vivo research confirmed the hypothesis that “using an accelerator for proliferation of progenitor will lead to development of open apexes in non-vital immature teeth”.