A crown-to-root ratio more severe than 1:2 indicates prognosis.

• A. Improved prognosis
• B. No effect on prognosis
• C. Unknown relation
• D. Worsened prognosis

Answer: (D)

The main idea here is that tooth prognosis depends on how much root support remains relative to the crown, captured by the crown-to-root ratio. If the crown-to-root ratio is more severe than 1:2, there is relatively less root support for the size of the crown, so occlusal forces have a larger lever arm and the tooth is more prone to mobility, attachment loss, and failure over time. In other words, the tooth is less able to withstand function, leading to a worse prognosis. A ratio that is more favorable (shorter crown relative to root) would suggest a better outlook, while ratios worse than 1:2 indicate poorer long-term survival.