Clinical Evaluation of Primary Stability and Optimal Loading Time of Orthodontic Microimplants within the First Week Post Insertion

Aim: This study evaluated the maximum primary stability and the optimal loading time of orthodontic microimplants within the 1 st week of insertion. Materials and Methods: In 12 patients, 24 orthodontic microimplants of diameter 1.5 and length 6 mm were inserted between maxillary 1 st permanent molar and 2 nd premolar, 7 mm from the alveolar crest. Resonance frequency analysis (Osstell ISQ device) was used to measure the stability at the time of insertion (T0), at 24 hours (T1), at 48 hours (T2), and at 7 days after insertion (T3) without loading the microimplants. The data were processed on SPSS version 19. Results: Mann–Whitney U , Kruskal–Wallis, and Wilcoxon signed-rank tests were applied for statistical analysis. The difference between the stability throughout the four time intervals was statistically significant ( P = 0.008), indicating that time has an effect on the primary stability. The comparison of T0 with T2 ( P = 0.04), T1 with T2 ( P = 0.035), and T2 with T3 ( P = 0.003) was statistically significant, suggesting a decrease in the primary stability at 48 hours after microimplant insertion. The comparison of T0 with T1, T0, with T3 and T1 with T3 was statistically insignificant. Conclusion: The maximum primary stability can be found up to 24 hours and on the 7 th day of microimplant insertion. Therefore, we recommended loading of orthodontic microimplants at these time intervals, whereas it should be avoided at 48 hours of placement.