Space / Bolton’s Analysis
Part of the Orthodontics Poster Collection
The Bolton Analysis, created by Wayne A. Bolton, serves as a method for evaluating the difference in size between upper (maxillary) and lower (mandibular) teeth. Its primary purpose is to assess the ideal relationship between the upper and lower dental arches. This analysis involves measuring the mesio-distal width of each tooth and is divided into two distinct assessments.
How is it calculated?
The 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.
An overall ratio of more than 91.3% indicates that the mandibular teeth are bigger when compared to normal. A ratio smaller than 91.3% would mean the mandibular teeth are smaller than normal.
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
An overall ratio of more than 77.2% means that the mandibular teeth are bigger when compared to normal. A ratio smaller than 77.2% would mean the mandibular teeth are smaller than normal.
Having a different ratio than normal is referred to as Bolton Discrepancy.
Arch Perimeter Analysis
Arch perimeter analysis is a diagnostic and treatment planning method used to evaluate the overall size and shape of a patient's dental arches. This analysis involves measuring the total perimeter of the upper (maxillary) and lower (mandibular) arches. By examining these measurements, you can assess the adequacy of arch size and detect any discrepancies or irregularities in arch shape.
The primary goals of arch perimeter analysis in orthodontics are to:
Identify crowding or spacing issues: By comparing the measured arch perimeters with the expected or ideal arch sizes, you can determine if there is crowding (insufficient space) or spacing (excessive space) between the teeth.
Customize treatment plans: The analysis helps you decide whether orthodontic treatment is necessary. Understanding arch perimeter measurements enables you to tailor treatment plans to the specific needs of each patient, ensuring a more precise and effective approach to orthodontic care.
Predict treatment outcomes: Arch perimeter analysis can also assist in predicting the results of orthodontic treatment, allowing both the orthodontist and the patient to have realistic expectations regarding the final alignment and occlusion (bite) of the teeth.
How to measure?
Tow measurements are required for intra-maxillary analysis of space requirement:
Space required
Space available
Determination of space required:
Using dental callipers for manual measurement or digital software for digital models. Measure the mesiodistal dimension of all the teeth mesial to the first molar (54321/12345).
Determination of space available:
Use the brass wire from mesio-buccal line angle of first right molar, pass the wire alone the buccal cusps and incisal edges in the anterior region, pass the wire on the left quadrant till the mesio-buccal line angle of the left first molar.
Mark the wire and measure the wire, which gives you the arch length.
Note: In case of proclined incisors, pass the brass wire in the cingulum region, and if the anterior teeth are retroclined, pass the wire labial to them like a smooth curve.
Determination of discrepancy:
The difference between the space required and space available gives the arch discrepancy or excess.
If the tooth material is more than the arch length, the space available for alignment is not sufficient results in crowding.
If the tooth material is less than the space, then there can be spacing.
