A lower second molar is tipped mesially and is being corrected with a coil spring. What will this correction cause?

Correct answer: D. Supraeruption and increased bite

• A. A coil spring for uprighting causes supraeruption, not infraeruption.
• B. Incorrect combination. Uprighting causes supraeruption (not infraeruption) with an increase in bite.
• C. Uprighting with a coil spring does cause supraeruption — but it INCREASES the bite (increased vertical occlusal space), not reduces it.
• D. When a mesially tipped second molar is uprighted with a coil spring, the mesial root tip moves distally and the crown rotates upward — causing SUPRAERUPTION. As the tooth comes into better vertical position, it INCREASES the bite (occlusal vertical dimension). This is a well-known side effect of molar uprighting.