Histologic tissue response to furcation perforation repair using mineral trioxide aggregate or dental pulp stem cells loaded onto treated dentin matrix or tricalcium phosphate.

OBJECTIVES: The aim of this study is to compare the effect of treated dentine matrix (TDM) and tricalcium phosphate (TCP) scaffolds on odontogenic differentiation and mineralization of dental pulp stem cells (DPSCs) in furcation perforations created in the pulp chamber floor of premolar teeth in dogs. MATERIAL AND METHODS: DPSCs were isolated and cultured from the dental pulp of the maxillary left second and third premolars of dogs. The DPSCs were loaded on TCP (SC+TCP) and TDM (SC+TDM) scaffolds and inserted into intentionally perforated pulp chamber floors of premolars in dogs; six teeth were used for each group. Three more groups of six specimens were created, and mineral trioxide aggregate (MTA), TDM, and TCP were inserted into the perforations to act as controls. An intact premolar and no treatment in the perforation site were used as positive and negative controls respectively. After 3 months, the animals were sacrificed and the type of inflammation, presence of dentine, continuation and type of cementum, type of connective tissue, and presence of foreign body reaction were evaluated, and significant differences were between groups determined using the Fisher's exact test. The evaluation of the amount of inflammation and the percentage of new bone formation was evaluated using the Mann-Whitney U test. RESULTS: The negative control group was associated with severe inflammation and granulation tissue formation. In the positive control group, intact periodontal tissues and no inflammation were observed. Dentine bridge formation was not seen in specimens of any group. The specimens in the SC+TDM group were associated with significantly more bone formation than other groups (P < 0.001). The amount of inflammation was less than 10 % in specimens of all groups with the exception of three specimens in the TCP group that were categorized as 10-30 %. Chronic inflammation without foreign body reactions was the major pattern of inflammation in groups. Formation of cementum with a cellular and continuous appearance was seen in all specimens. CONCLUSIONS: SC+TDM was associated with significantly more bone formation when used to repair uninfected furcation perforations in the premolar teeth of dogs. CLINICAL RELEVANCE: Application of TDM as a biological scaffold in combination with DPSCs may offer an advantage during the repair of root perforation defects.

The effect of purmorphamine and sirolimus on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells.

Small molecules have been introduced as less expensive biologically active compounds that can regulate different developmental phenomena. Purmorphamine and sirolimus are two small molecules that, according to some studies, possess certain osteomodulatory effects. This study was set out to highlight the appropriate dose and response time of these small molecules on enhancement of osteogenesis in human bone marrow-derived mesenchymal stem cells from early to mid and late stages of differentiation. Alkaline phosphatase activity, matrix mineralization and expression of osteoblast genes were quantitatively assessed in vitro. For the in vivo study, we transplanted stem cell-based constructs subcutaneously into rats, and treated them daily with the most promising doses of the small molecule. The constructs were analyzed by real-time PCR and histological staining. Our results showed that Sirolimus reduced osteogenic differentiation of mesenchymal stem cells by decreasing alkaline phosphatase activity at dose of 100nM after 14 days and mineralization of the matrix at 14 and 21 days post-induction. Purmorphamine induced up-regulation of alkaline phosphatase activity and expression of RUNX-2 at day 14. Up-regulation of osteocalcin was detected at the 3 and 5µM doses of purmorphamine on day 14 post-induction. Matrix mineralization remained unchanged in the presence or absence of purmorphamine. This dose of small molecule also accelerated expression of Alkaline phosphatase transcripts in vivo. In conclusion, sirolimus had an inhibitory effect on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells; while purmorphamine, particularly at a dose of 3µM, showed a promotive effect in vitro and in vivo.