American Board of Orthodontics (ABO) Practice Exam

To determine how much arch space can be gained from the bilateral reduction of 50% of enamel, it's essential to understand the mechanics of tooth reduction and its implications on arch space.

When enamel is reduced, particularly in a bilateral manner, it typically leads to a change in the overall volume and shape of the tooth. The reduction in enamel can allow for redistributing the space within the arch. Specifically, research shows that reducing the enamel on both sides of the arch can create additional space that can be measured.

The estimated gain in arch space from a bilateral reduction of enamel is usually around 9.8 mm based on the volumetric changes associated with such a reduction, taking into account the decrease in the overall tooth bulk that accompanies enamel reduction.

This understanding aligns with the physiological principles of orthodontic treatments that involve creating space in the arch for alignment or to facilitate other therapeutic goals. Such clinical outcomes can be crucial for effective orthodontic planning and execution. Therefore, the answer of 9.8 mm reflects the realistic clinical gain expected from the enamel reduction procedure described.