Systemic bone marker expression induced by grey and white mineral trioxide aggregate in normal and diabetic conditions.

AIM: To investigate the relationship between diabetes mellitus and local/systemic effects of both grey and white mineral trioxide aggregate (MTA) Angelus on bone marker expression. METHODOLOGY: Wistar rats were divided into two groups: healthy and diabetic (Alloxan induced), which were further divided into three subgroups (control, GMTA Angelus and WMTA Angelus). Polyethylene tubes filled with MTA materials or empty tubes were implanted in dorsal connective tissue. On days 7 and 30, blood samples were collected for calcium, phosphorus and ALP measurement. The animals were euthanized; implanted tubes were removed and processed for immunohistochemical analysis of osteocalcin (OCN) and osteopontin (OPN). Kruskal-Wallis followed by Dunn's multiple comparison test was performed for nonparametric data, and anova followed by Tukey's test for parametric data. RESULTS: No difference in systemic serum calcium levels between both groups was observed. On day 7, serum phosphorus levels within the WMTA healthy group were higher than that of the diabetic group. On day 30, healthy rats exhibited lower phosphorus levels than diabetic ones. At both time points, the diabetic group was associated with more ALP activity than the healthy group. Immunohistochemical analyses of the healthy group revealed OCN- and OPN-positive cells in the presence of both MTA materials. However, under diabetic conditions, both OCN and OPN were absent. CONCLUSION: Both MTA materials were associated with an increase in serum calcium, phosphorus and ALP, suggesting a potential systemic effect, along with triggered differentiation of OCN- and OPN-positive cells. Moreover, in diabetic conditions, an inhibitory effect on MTA-induced differentiation of OCN- and OPN-positive cells was detected.

RUNX-2, OPN and OCN expression induced by grey and white mineral trioxide aggregate in normal and hypertensive rats.

AIM: To investigate whether hypertension affects mineralization associated with white and grey mineral trioxide aggregate (MTA Angelus® ) implanted subcutaneously into rats by assaying osteoblastic biomarkers. METHODOLOGY: Polyethylene tubes containing grey MTA Angelus® , white MTA Angelus® , intermediate restorative material (IRM; positive control) or an empty tube (negative control) were implanted into the dorsal connective tissue of spontaneous hypertensive (n = 12) and Wistar (normotensive; n = 10) rats. Half of the rats in each group were killed after 7 days, and the remaining after 30 days. Tubes with surrounding tissue were removed, and immunostaining was performed to detect RUNX-2, OPN and OCN proteins. The normality of data was analysed using the Shapiro-Wilk test. Comparison of two independent groups was performed using the Mann-Whitney U-test, to detect a significant difference. A post hoc test accounting for multiple comparisons was performed following Tukey's test (P < 0.05). RESULTS: Under hypertensive conditions after 30 days, both MTA materials were associated with immunolabelling for RUNX-2 from low to moderate, which was less than that observed at normal blood pressure and the 7-day groups (P < 0.05). The expression of OPN and OCN proteins under both MTA conditions was considered low after both 7 and 30 days for the hypertensive condition, and was less than that in animals with normal blood pressure after 30 days (P < 0.05). No immunostaining for any biomarkers in the control and IRM groups was observed (P < 0.05). CONCLUSION: Hypertension decreased the immunostaining of RUNX-2, OPN and OCN biomarkers in response to MTA. Thus, hypertension can jeopardize the mineralization ability of MTA and may have a negative impact on endodontic treatment outcomes.

Mineral trioxide aggregate improves healing response of periodontal tissue to injury in mice.

BACKGROUND AND OBJECTIVE: Mineral trioxide aggregate (MTA) is a biomaterial used in endodontic procedures as it exerts beneficial effects on regenerative processes. In this study, we evaluate the effect of MTA on healing of periodontal ligament (PDL) and surrounding tissue, following injury, in a transgenic mouse model and on the differentiation of murine mesenchymal progenitor cells in vitro. MATERIAL AND METHODS: We used an inducible Cre-loxP in vivo fate mapping approach to examine the effects of MTA on the contributions of descendants of cells expressing the αSMA-CreERT2 transgene (SMA9+ ) to the PDL and alveolar bone after experimental injury to the root furcation on the maxillary first molars. Col2.3GFP was used as a marker to identify mature osteoblasts, cementoblasts and PDL fibroblasts. The effects of MTA were examined 2, 17 and 30 days after injury and compared histologically with sealing using an adhesive system. The effects of two dilutions of medium conditioned with MTA on proliferation and differentiation of mesenchymal progenitor cells derived from bone marrow (BMSC) and periodontal ligament (PDLC) in vitro were examined using the PrestoBlue viability assay, alkaline phosphatase and Von Kossa staining. The expression of markers of differentiation was assessed using real-time PCR. RESULTS: Histological analyses showed better repair in teeth restored with MTA, as shown by greater expansion of SMA9+ progenitor cells and Col2.3GFP+ osteoblasts compared with control teeth. We also observed a positive effect on differentiation of SMA9+ progenitors into osteoblasts and cementoblasts in the apical region distant from the site of injury. The in vitro data showed that MTA-conditioned medium reduced cell viability and osteogenic differentiation in both PDLC and BMSC, indicated by reduced von Kossa staining and lower expression of osteocalcin and bone sialoprotein. In addition, cultures grown in the presence of MTA had marked decreases in SMA9+ and Col2.3GFP+ areas as compared with osteogenic medium, confirming reduced osteogenesis. CONCLUSION: MTA promotes regeneration of injured PDL and alveolar bone, reflected as contribution of progenitors (SMA9+ cells) into osteoblasts (Col2.3GFP+ cells). In vitro, MTA-conditioned medium fails to promote osteogenic differentiation of both PDLC and BMSC.