Primary goal of pre-orthodontic or phase I alignment of severely crowded incisors

 # The primary goal of pre-orthodontic or phase I alignment of severely crowded incisors that are planned for permanent extraction (e.g. premolar) is to:

A. Reduce the risk of post treatment gingival recession

B. Decrease the overall duration of the comprehensive treatment

C. Prevent external apical root resorption of adjacent teeth

D. Align the roots parallel for optimal force distribution during space closure

The correct answer is D. Align the roots parallel for optimal force distribution during space closure

In extraction cases with severe incisor crowding, initial (phase I) alignment using light round NiTi wires uprights and derotates the anterior teeth, paralleling their roots to position the center of resistance (CR) along the retraction force vector—enabling bodily translation rather than uncontrolled tipping during subsequent en masse space closure (e.g., via chain or coil springs). This optimizes biomechanical efficiency, reduces unwanted extrusion or lingual crown tipping (by 50–70% vs. unaligned starts), and enhances overall control, as emphasized in treatment sequencing guidelines. While it secondarily mitigates resorption risk (C) through lighter, more physiologic forces and may shorten total duration (B) by streamlining mechanics, root parallelism is the foundational goal for precise, stable closure in crowded arches.