How to use – Bolton Analysis

1. What is the Bolton analysis?

The Bolton analysis assesses tooth-size discrepancies between the maxillary and mandibular arches. It is fundamental for proper occlusion and orthodontic planning.

2. Why is it useful?

It detects disproportion between both arches. A discrepancy can prevent proper space closure or alignment.

3. What should you measure?

• The mesiodistal width of anterior teeth (canine to canine).
• If desired, include premolars (first premolar to first premolar) to compute the overall Bolton ratio.

4. How do I interpret the result?

• Ideal anterior value: 77.2%.
• Ideal overall value: 91.3%.
• A lower value indicates small lower teeth.
• A higher value indicates large lower teeth.

5. What to do if there is a discrepancy?

• Consider interproximal reduction (IPR).
• Composite build-ups.
• Tooth repositioning to compensate for the excess or deficit.

6. Example

Suppose your upper anterior sum is 48 mm and the lower is 38 mm. The index is:

38 ÷ 48 × 100 = 79.2% → There is a lower excess (above 77.2%).