3D Comparison of Anterior Teeth Retraction and Anchorage Control Between En-masse and Two-step Mechanics

3D Comparison of Anterior Teeth Retraction and Anchorage Control Between En-masse and Two-step Mechanics

3D Comparison of Anterior Teeth Retraction and Anchorage Control Between En-masse and Two-step Mechanics: A Randomized Prospective Clinical Trial

The aim of this study is to compare en masse (EM) and two-step anterior teeth retraction (TSR) evaluated by means of three-dimensional images superimposition. Thirty-two adult patients with bimaxillary protrusion planed for treatment with four first premolar extractions will be enrolled. All patients will be randomly allocated in a 1:1 ratio to either EM (n=16) group or the TSR (n=16) group. Cone bean computed tomography will be taken before and after anterior retraction. A blind observer will construct separate 3D models for maxillary and mandibular surfaces using the anterior cranial fossa to register models of before and after space closing. Quantitative assessment of posterior anchorage loss and amount of anterior teeth retraction are the main outcomes. The secondary outcomes are the inclination of the molars, canines and incisors.

All 32 patients will be randomly allocated in a 1:1 ratio to either en masse (n=16) group or the two-step anterior retraction (n=16) group.

After extraction of the four premolars the posterior teeth will be tied-together and the six anterior teeth will be retracted by sliding mechanics.

After extraction of the four premolars the posterior teeth will be tied-together and the canines will be retracted by sliding mechanics. After the distalization of the canines they will be tied to the posterior teeth and the incisors will be retracted by sliding mechanics.

Quantitative assessment of posterior anchorage loss between the two groups as measured by tomographic superimposition at the end of space closure.

Quantitative assessment of anterior teeth retraction between the two groups as measured by tomographic superimposition at the end of space closure.

Quantitative assessment of molars inclination between the two groups as measured by tomographic superimposition at the end of space closure.

Quantitative assessment of canines inclination between the two groups as measured by tomographic superimposition at the end of space closure.

Quantitative assessment of incisors inclination between the two groups as measured by tomographic superimposition at the end of space closure.

Inclusion Criteria: Angle Class I malocclusion; Bimaxillary protrusion; Convex profile; All natural teeth present in the mouth; Absence of crowding or with negative discrepancy up to 4mm; Absence of vertical and transverse occlusal problems; Good oral health; Good general health. Exclusion Criteria: Lack of time to attend consultations; Patients with severe systemic and psychological illness; Patients with parafunction (bruxism), reflux or eating disorders; Presence of periodontal disease;

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