Effects of mesenchymal stem cell transfer on orthodontically induced root resorption and orthodontic tooth movement during orthodontic arch expansion protocols: an experimental study in rats.

OBJECTIVES: The aim was to evaluate the effects of mesenchymal stem cell (MSC) transfer to periodontal ligament (PDL) on the inhibition and/or repair of orthodontically induced root resorption (OIRR) during and after arch expansion and on the orthodontic tooth movement (OTM) rate of the maxillary first molar teeth of rats. MATERIAL AND METHODS: Sixty Wistar rats were divided into three groups as the untreated group, MSC and control injections during the expansion period group (EMSC-EC), and MSC and control injections at the retention period group (RMSC-RC). Fifty grams of orthodontic force was applied to the maxillary first molar teeth of the rats for 14 days in the vestibular direction, and then, 20 days of retention was carried out. MSCs and control injections were performed every 3 days in the EC, RC, EMSC, and RMSC groups. At the end of the experiment, samples were prepared for OTM evaluation, mRNA expression analysis, micro-computed tomography measurements, cementum thickness calculations, and structural examinations. RESULTS: The amount of OTM in EMSC group was significantly higher than in EC group (P < 0.001). MSC transfer during the expansion and retention periods reduced the number of resorption lacunae, volumetric and linear resorptive measurements, and cyclooxygenase-2 and receptor activator of nuclear factor kappa B ligand (RANKL) mRNA expression levels, and increased the osteoprotegerin (OPG) expression levels, OPG/RANKL ratio, and cementum thickness in the EMSC and RMSC groups. CONCLUSIONS: MSC transfer to PDL during expansion increased the amount of OTM. Injection of MSC during the retention period was found to be slightly more effective in prevention and/or repair of OIRR than MSC transfer during the expansion period.

Comparison of dental measurements between conventional plaster models, digital models obtained by impression scanning and plaster model scanning.

OBJECTIVE: Comparison of dental measurements between conventional plaster models, digital models obtained by impression scanning and plaster model scanning. PURPOSE: To evaluate and to compare the accuracy and reliability of tooth size, arch width and Bolton tooth size discrepancy measurements on 3 Dimensional (3D) digital models obtained by plaster dental model scanning, dental impression scanning and conventional plaster models. MATERIAL AND METHODS: This study was carried out on the maxillary and mandibular dental models of 25 patients with Angle Class I molar relationship and minimal crowding. Mesio-distal dimensions of the teeth, intercanine and intermolar arch width, and Bolton tooth size discrepancy measurements were calculated by conventional methods on plaster models, digital methods and on 3D models obtained from plaster model scanning and impression scanning. All measurements were repeated after three weeks for each of the investigated methods. Reliability of measurements was evaluated by Dahlberg formula and Pearson Correlation Coefficient. Comparisons of dental measurements between three methods were achieved with ANOVA Test. RESULTS: The repeated measurements were highly correlated for all methods. Method error was found within clinically acceptable limits. There was no significant difference between dental measurements on plaster dental models, digital models obtained from plaster dental model scanning and dental impression scanning. Results showed the methods being highly reliable and accurate for tooth size, arch width and Bolton analysis at total and anterior proportion calculation. CONCLUSION: Digital measurements of tooth size, arch width and Bolton tooth size discrepancy on digital models obtained from plaster dental model scanning and dental impression scanning showed high accuracy and reliability. There was no significant difference between the three methods for dental measurements.