Comparison of sagittal anchorage conservation of mini-implants and modified Nance palatal buttons.

Objective: To compare the anchorage potential of mini-implants with modified Nance palatal buttons during simultaneous first and second maxillary molar distalization.

Methods: Mini-implants (1.4 x 10 mm) placed to obtain indirect anchorage for maxillary molar distalization using a superelastic Ni-Ti open coil spring were compared with anchorage derived from a modified Nance palatal button incorporated in a distal jet appliance. Appliances were placed bilaterally in 19 adolescent patients. Lateral cephalograms with guide wires to differentiate the right from left sides were used for evaluation. All measurements (angular and linear) were obtained from these guide wires.

Results: Anchorage loss at the first premolar was 13% with mini-implant-supported Ni-Ti coil spring appliances and 24.75% with the Nance palatal button (distal jet appliance) on the right side. On the left side, anchorage loss was 15.4% with mini-implant-supported Ni-Ti coil spring appliances and 23.9% with the Nance palatal button (distal jet appliance).

Conclusion: Mini-implants do not provide absolute anchorage when used indirectly. However, anchorage conservation is more efficient than modified Nance palatal buttons.