Cytotoxicity of Calcium Hydroxide on Human Umbilical Cord Mesenchymal Stem Cells

Abstract Objective: To examine the cytotoxicity of calcium hydroxide on human umbilical cord mesenchymal stem cells (HUCMSC) to understand the characteristics for use in regenerative dentistry procedures especially regenerative endodontics. Material and Methods: HUCMSC was isolated, cultured, and confirmed by flow cytometry. The biological characteristics, such as cell morphology, proliferation, and protein expression, were screened. To check the cytotoxicity, HUCMSC was cultured and divided into two groups, the control group (cultured in minimum essential medium (MEM) alpha) and calcium hydroxide group (cultured in MEM alpha and calcium hydroxide). Methyl-thiazole-tetrazolium (MTT) assay was done on different concentrations of calcium hydroxide (0.39 to 25 µg/mL) and the cells were observed and counted. One-way ANOVA test was used with a significance level set at 5%. Results: Flow cytometric analysis confirmed positive of CD73, CD90, CD105, negative of CD45 and CD34. A significant difference was found between the concentration of 6.25 and 3.125 µg/mL (p=0.004). There was no significant difference among 6.25, 12.5 and 25 µg/mL concentrations. There was also no significant difference among 0.39, 0.78, 1.56, and 3.125 µg/mL concentrations. Conclusion: Even though calcium hydroxide is a medicament of choice in clinical endodontics, it decreases the viability of HUCMSC. The lower the concentration of calcium hydroxide, the higher the viability of HUCMSC.

Receptor Activator of Nuclear Factor-Kappa Ligand and Osteoprotegerin Expressions on Hyperglycemic Wistar Rats (Rattus Novergicus) During Orthodontic Tooth Movement

Abstract Objective: To investigate the differences of receptor activator of nuclear factor-κB ligand (RANKL) and Osteoprotegerin (OPG) expressions between normoglycemic and hyperglycemic Wistar rats (Rattus Novergicus) during Orthodontic Tooth Movement (OTM). Material and Methods: This study was true experimental with post-test group only. Thirty-two healthy male Wistar rats, weighted around 200-250 grams, 12-20 weeks old, were used as OTM animal study. They were divided into 2 groups (n=16), normoglycemic rats (normal blood glucose 80-120 mg/dl) and hyperglycemic rats (>250 mg/dl) induced by Streptozotocin with a dose of 30 mg in PBS injection intraperitoneally. A NiTi closed coil spring was mounted between maxillary first molar and incisors with the light force 10gf/mm2 in both groups to induce OTM. The studied animals were then terminated on days 1, 3, 6, and 9, respectively, and premaxilla was extracted. RANKL and OPG expression were examined utilizing immunohistochemistry (IHC) analysis. One-way ANOVA and Tukey HSD (p<0.05) were utilized to analyze the differences in the expression of RANKL and OPG between groups. Results: The hyperglycemic group on day 1, 9 rats showed a significant increase in the expression of RANKL, whereas OPG expression decreased significantly on days 1, 3, and 9. Conclusion: There was a significant increase of RANKL expression and a decrease of OPG expression in hyperglycemic rats as documented immunohistochemically.