Effects of adipose-derived mesenchymal stem cells on bone formation and stability of orthodontic mini screw implants.

The aim of this randomized controlled experimental animal study was to evaluate the differences between the stability of Stem cell (SC)- treated orthodontic mini screw Implants (MSIs); with or without Boron versus non-Stem cell treated groups under different force levels and to assess the bone formation around those mini implants. 15 New Zealand white adult male rabbits were randomly divided into three groups as; stem cell, stem cells+boron and control. 77 titanium customized orthodontic miniscrews (Osmed Dental, Istanbul, Turkey) with a length of 6 mm and a diameter of 1.4 mm were implanted in each proximal tibia and different force levels (0, 150, and 300 cN) were applied to each group. In a 21-day retention period, the implant stability was assessed by resonance frequency analysis (RFA) and Implant Stability Quotient (ISQ) values were measured by Osstell device (Integration Diagnostics AB, Göteborg, Sweden). At the end of the study MSIs were evaluated 3 dimensionally with micro Computed Tomography (µCT); (SkyScan 1172; Bruker Cooperation, Kontich, Belgium). Descriptive statistics were performed for the statistical analysis. Since the data were not normally distributed, non-parametric tests were used. All baseline values and sub-group differences were compared by Kruskal-Wallis test. The data revealed that primary stability of all miniscrews was similar in all groups under 0 cN (p = 0.135), 150 cN (p = 0.779), and 300 cN (p = 0.498) force levels at the start of the experimental procedure. At the end of the study no statistically significant changes were determined in ISQ values of any force groups, under 0 cN (p = 0.057), 150 cN (p = 0.893), and 300 cN (p = 0.972) force levels. µCT findings suggest that Bone Volume to Tissue Volume (p = 0.053), Bone Surface to Bone Volume (p = 0.061), Trabecular thickness (p = 0.061), Trabecular number (p = 0.099), Trabecular separation (p = 0.159), closed porosity (p = 0.097) and open porosity (p = 0.098) value changes were not statistically significant in 3 main groups. Key Words: Stem Cells, Mini Screw Implants, Bone Formation, Mini Screw Stability, Boron