Assessment of changes following en-masse retraction with mini-implants anchorage compared to two-step retraction with conventional anchorage in patients with class II division 1 malocclusion: a randomized controlled trial.

BACKGROUND

No randomized controlled trial has tried to compare treatment outcomes between the sliding en-masse retraction of upper anterior teeth supported by mini-implants and the two-step sliding retraction technique employing conventional anchorage devices.

OBJECTIVE

To evaluate skeletal, dental, and soft tissue changes following anterior teeth retraction.

DESIGN AND SETTING

Parallel-groups randomized controlled trial on patients with class II division 1 malocclusion treated at the University of Al-Baath Dental School in Hamah, Syria between July 2011 and May 2013.

PARTICIPANTS

One hundred and thirty-three patients with an upper dentoalveolar protrusion were evaluated and 80 patients fulfilled the inclusion criteria. Randomization was performed using computer-generated tables; allocation was concealed using sequentially numbered opaque and sealed envelopes. Fifty-six participants were analysed (mean age 22.34 ± 4.56 years). They were randomly distributed into two groups with 28 patients in each group (1:1 allocation ratio).

INTERVENTION

Following first premolar extraction, space closure was accomplished using either the en-masse technique with mini-implants or the two-step technique with transpalatal arches (TPAs).

MAIN OUTCOME MEASURE

The antero-posterior displacements of upper incisal edges and upper first molars were measured on lateral cephalograms at three assessment times. Assessor blinding was employed.

RESULTS

A bodily retraction (-4.42 mm; P < 0.001) with a slight intrusion (-1.53 mm; P < 0.001) of the upper anterior teeth was achieved in the mini-implants group, whereas upper anterior teeth retraction was achieved by controlled palatal tipping in the TPA group.

CONCLUSIONS

When retracting anterior teeth in patients with moderate to severe protrusion, the en-masse retraction based on mini-implants anchorage gave superior results compared to the two-step retraction based on conventional anchorage in terms of speed, dental changes, anchorage loss, and aesthetic outcomes.