Effect of Immediate Loading on the Stability of Orthodontic Mini-Implant-An Ex Vivo Study.

INTRODUCTION Mini-implant placement has become a routine method for providing anchorage in orthodontic treatment. The stability of these implants is influenced by several factors, including implant design, bone quality, site preparation, insertion angle, and loading protocol. Among these, implant and bone quality are largely unmodifiable. Resonance Frequency Analysis (RFA) is widely used to assess implant stability. This ex vivo study aimed to evaluate the impact of immediate loading on the stability of orthodontic mini-implants using RFA.

Materials And Methods

This prospective animal study assessed the primary stability of 72 self-drilling stainless steel mini-implants of three lengths (1.3 mm × 6 mm, 1.3 mm × 8 mm, and 1.3 mm × 10 mm). A 2 N load was applied using nickel-titanium coil springs. Stability was measured by RFA immediately after force application (T0) and after 5 weeks (T1).

Results

Initial stability was comparable across all implant lengths. After 5 weeks of loading, all groups demonstrated a reduction in stability. The 6 mm implants showed a significantly greater loss of stability (5.31 ± 4.89) compared to the 8 mm (2.36 ± 4.08) and 10 mm (2.39 ± 1.64) implants. All lengths exhibited statistically significant stability loss post-loading (6 mm, p = 0.001; 8 mm, p = 0.009; 10 mm, p = 0.001).

Conclusion

Variations in implant length did not significantly affect immediate stability following loading. However, over time, 6 mm implants experienced greater stability loss compared to 8 mm and 10 mm implants. Despite this, shorter implants exhibited slightly higher initial stability under load.