Direct pulp capping with mineral trioxide aggregate: an immunohistologic comparison with calcium hydroxide in rodents.

INTRODUCTION: The aim was to evaluate the proliferation of pulp cells 1, 3, and 7 days after direct pulp capping with ProRoot MTA (MTA) and to compare the results with calcium hydroxide (Ca(OH)(2)). METHODS: An occlusal cavity was prepared in 36 molar teeth of 18 Wistar rats. Then MTA or Ca(OH)(2) was placed on the exposed pulp. All cavities were restored with composite. After 1, 3, and 7 days the animals were killed. One hour before scarification 5-bromo-2'-deoxyuridine (BrdU) was injected into the intraperitoneal cavity for immunohistologic analysis. BrdU was incorporated into the cell nucleus during the S phase of the cell cycle. Proliferating cells were tagged and counted by using alkaline phosphatase and anti-alkaline phosphatase antibody staining. Three animals (6 molar teeth) served as controls and were not further treated. The number of the tagged cells was statistically analyzed by comparing the results of the 3 groups. A Bonferroni correction was performed, because the data of the Ca(OH)(2)- group was used 3 times for pairwise comparison. RESULTS: The marked cells were identified as fibroblasts, endothelial cells (after 1, 3, and 7 days), and Höhl cells (after 7 days). The MTA group showed a similar amount of Höhl cells when compared with the Ca(OH)(2) group (P > .05). One day and 7 days after capping, no significant differences were observed between the 2 tested groups and the controls (P > .05). After 3 days, significantly more cells were stained in the MTA and Ca(OH)(2) groups than in the control group (P < .016). CONCLUSIONS: Immunohistologic analysis demonstrated that MTA showed similar results when compared with Ca(OH)(2) within the first week after direct pulp capping.

Mineral trioxide aggregate for direct pulp capping: a histologic comparison with calcium hydroxide in rat molars.

OBJECTIVES: Several studies reported superior healing results for ProRoot mineral trioxide aggregate (MTA; Dentsply Tulsa) cement in direct pulp capping when compared to calcium hydroxide. However, this could not be confirmed by other authors. The aim of this study was to compare the reaction of MTA-treated rat pulp tissue to calcium hydroxide [Ca(OH)2]-treated rat pulp tissue in direct pulp capping after 1 to 70 days. METHOD AND MATERIALS: Seventy-two caries- free, maxillary right and left first molars of 36 Wistar rats were prepared with an occlusal cavity. The pulp chambers were then perforated with a sharp probe. For each of four time periods, MTA was placed on the exposed pulp of 10 molars according to the manufacturer's instructions, and Ca(OH)2 was placed on 8 molars. All cavities were then filled with dentin adhesive and flowable composite. The animals were sacrificed 1, 3, 7, and 70 days after pulp capping. The pulps were histologically analyzed (light and transmission electron microscopic) for bacterial infection, inflammatory cells, necrosis, and reparative dentin and classified according to occurrence in scores from 1 to 4. To ensure that the coronal restorations did not leak, occlusal cavities were prepared in four maxillary molars of one rat. The coronal cavity was then sealed with resin. After 70 days, the rat was sacrificed, and the molars were immersed in new fuchsin. Data were statistically evaluated with the Kruskal-Wallis test (P<.05). RESULTS: The MTA group showed statistically significantly lower signs of necrosis 1 and 3 days after pulp capping when compared with the Ca(OH)2 group (P<.05). No other statistically significant differences were found (P>.05). After 70 days, all pulps displayed healthy tissue. In the leakage test no specimens revealed any dye penetration. CONCLUSION: MTA showed equally good results as Ca(OH)2 and can berecommended clinically for direct pulp capping.

Human plasma thrombopoietin levels are regulated by binding to platelet thrombopoietin receptors in vivo.

BACKGROUND: Data from several studies support the hypothesis that thrombopoietin (TPO) plasma levels are regulated via circulating platelet (PLT) numbers by binding to PLT TPO receptors (TPO-Rs). In this study, PLT numbers and TPO plasma levels were measured following the transfusion of unmanipulated, sham-saturated, and TPO-R-saturated PLT preparations to provide additional in vivo evidence for this regulatory mechanism. STUDY DESIGN AND METHODS: Following in vitro experiments to characterize pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) binding characteristics, PLT numbers and TPO plasma levels were measured following the transfusion of unmanipulated, sham-saturated, and TPO-R-saturated PLT preparations in thrombocytopenic patients. Sham-saturated and TPO-R-saturated PLTs were prepared by a 1-hour incubation without and with 40 ng per mL of PEG-rHuMGDF, respectively, and subsequent washing and resuspension. RESULTS: In vitro, 2.72 +/- 0.8 ng of PEG-rHuMGDF per 1 x 10(8) PLTs was bound within 1 hour of incubation. No additional PEG-rHuMGDF was bound following a second incubation with PEG-rHuMGDF, and bound PEG-rHuMGDF was not released over time. In vivo, TPO plasma levels decreased significantly (p < 0.001), by 30.7 +/- 5.8 and 20.9 +/- 2.1 percent after transfusion of unmanipulated and sham-saturated PLT preparations, respectively. However, TPO plasma levels were unaffected after the transfusion of TPO-R-saturated PLTs despite comparable transfusion-induced PLT count increases. CONCLUSION: These data strongly support the concept that binding to PLT TPO-R is directly involved in human TPO plasma level regulation in vivo.