Tooth Size and proportion is important to consider in orthodontic diagnosis and treatment planning since many malocclusions can occur as a result of abnormalities in tooth size.
The Bolton Analysis is a component in orthodontic diagnosis and treatment planning because it helps in determining disproportions in the size between maxillary and mandibular teeth.
For information regarding Bolton analysis, refer to the following topics:
What is Bolton analysis?
Bolton analysis determines the ratio of the mesiodistal widths of the maxillary teeth to the mandibular teeth using a formula introduced by Dr. Wayne A. Bolton. It shows whether there is any tooth size discrepancy between the upper and lower teeth. This analysis is recommended only in the permanent dentition, after the eruption of all permanent teeth.
When treating patients, instead of going through a time-consuming process of doing diagnostic set-ups, using the Bolton Analysis intermaxillary ratio can be used to assess maxillary or mandibular arch length deficiencies or tooth size discrepancies. This provides the clinician with a quick diagnostic tool to contribute to finishing in “excellent occlusion” with ideal overbite and overjet.
How is it calculated?
Overall ratio between the two arches is the percentage relationship of mandibular arch length to maxillary arch length.
- Mesiodistal width of twelve maxillary teeth
- Mesiodistal width of twelve mandibular teeth
The ratio between the two is the percentage relationship of mandibular arch length to maxillary arch length.
If the overall ratio is less than 91.3% it indicates that there is maxillary tooth material excess. The maxillary teeth are relatively too large compared to the mandibular teeth.
The anterior ratio between the two arches is the percentage relationship of mandibular anterior width to maxillary anterior width.
- Mesiodistal width of six anterior maxillary teeth
- Mesiodistal width of six anterior mandibular teeth
If the anterior ratio is less than 77.2%, it indicates maxillary anterior excess.
If the anterior ratio is more than 77.2%, it indicates mandibular anterior excess.
Normal occlusal relationships
Disharmony between the width of upper and lower teeth can be improved by:
- Expansion procedures
- In some cases, increasing the mesiodistal tooth size of the disproportionate tooth
ClearCorrect has several tools to help analyze where tooth discrepancies might be located.
Note: For cases that have pontics placed, the Bolton Analysis Table in ClearPilot calculates this as a missing tooth.
ClearCorrect Analysis of Tooth Discrepancies:
NOTE: Download a printable guide here.
Accessing Bolton Analysis tool in ClearPilot:
- Locate the Measurement tool icon in the top tool bar.
- Slide the toggle to activate Bolton table.
- The table will appear on the left. Use the top icons on the table to change orientation or drag to new location.
- To remove the table, click on the "X" in the Bolton window.