Understanding Bolton Analysis

Bolton’s Analysis

Bolton’s analysis evaluates teeth for both maxillary and mandibular arches for size discrepancies.

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According to Bolton, a ratio exists between the mesiodistal width of maxillary and mandibular teeth.
In cases of tooth size discrepancy, teeth in one arch may occupy more space than teeth in the opposite arch, leading to occlusal missing. So, such cases should be identified before treatment.

Bolton’s analysis

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Bolton Analysis Calculation Steps

Procedure

The sum of mandibular 12 teeth: Mesiodistal width of the first permanent mandibular molars of one side to the first permanent mandibular molar of the other side is measured and summed up.
The sum of maxillary 12 teeth: Mesiodistal width of first permanent maxillary molars of one side to first permanent maxillary molar of the other side is measured and summed up.
The sum of mandibular six teeth, i.e., anterior: Mesiodistal width of permanent mandibular canine of one side to permanent mandibular canine of another side, is measured and summed up.
A sum of maxillary six teeth, i.e., anterior: Mesiodistal width of permanent maxillary canine of one side to permanent maxillary canine of both? Er, the side is measured and summed up.

Estimation of Overall Ratio

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It is calculated by the following formula:

Overall Ratio = \(\frac{\text { Sum of mandibular } 12}{\text { Sum of maxillary } 12} \times 100\)

The ideal overall ratio is 91.3%. This indicates a good overbite and overjet relationship.
If the ratio is more than 91.3%. This indicates mandibular tooth material excess.
If the ratio is less than 91.3%. This indicates maxillary tooth material excess.
Quantification of overall tooth material excess is done by following formulas.

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Bolton Ratio in Orthodontic Treatment

For Maxillary Tooth Material Excess

= \(\text { Sum of maxillary } 12-\frac{\text { Sum of mandibular } 12 \times 100}{91.3}\)

Bolton Analysis Tools and Software

For Mandibular Tooth Material Excess

= \(\text { Sum of mandibular } 12-\frac{\text { Sum of maxillary } 12 \times 91.3}{100}\)

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Determination of Anterior Ratio

The anterior ratio is calculated by the following formula:

Understanding Tooth Size Discrepancy

Anterior Ratio = \(\frac{\text { Sum of mandibular } 6}{\text { Sum of maxillary } 6} \times 100\)

The ideal anterior ratio is 77.2%.
Suppose the ratio is more than 77.2%. This indicates mandibular anterior tooth material excess.
Suppose the ratio is less than 77.2%. This indicates maxillary anterior tooth material excess.
Quantification of overall anterior tooth material excess is done by following formulas.

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For maxillary anterior excess

= \(\text { Sum of maxillary } 6-\frac{\text { Sum of maxillary } 6 \times 100}{77.2}\)

For mandibular tooth anterior excess

= \(\text { Sum of mandibular } 6-\frac{\text { Sum of maxillary } 6 \times 77.2}{100}\)

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