RESUMEN
Objective:To study retention force durability of root-type attachments.Methods:Five magnetic attachments(Magfit EX-600),semi-precise stud-type attachments(Bedent) and precise stud-type attachments(Dalbo-classic) were fixed on a thermal-cycling and mechanical-loading machine respectively.The retention force of each attachment was measured at the baseline and after every 1,000 cycles of seating-removing.Results:The average retention force of magnetic attachments was(3.85?0.107) N at the baseline which attenuated for 3.38% after 10,000 cycles;The retention force of semi-precise group was(14.10?0.144) N originally and decreased 90.06% of the original force after 10,000 cycles.The primary force of the precise group was 33.14 N and was adjusted to(11.95?0.082) N as baseline attenuating for 74.56%.Conclusion: The retention force of magnetic attachments is lower than the stud attachments but is stable for 10 years.The retention force of stud-type attachments is larger at the baseline but reduced rapidly.