Bolton analysis

Bolton Analysis is a tooth analysis developed by Wayne A. Bolton to determine the discrepancy between the size of the maxillary and mandibular teeth. This analysis is used to assess the optimum interarch relationship by measuring the mesiodistal width of each tooth in both the upper and lower arches. It is crucial for ensuring proper occlusion in orthodontics, helping orthodontists diagnose and plan treatment for patients with malocclusion.

History

Wayne A. Bolton first presented this analysis in 1958, contributing significantly to the field of orthodontics. In 1962, he published another paper discussing the clinical applications of Bolton Analysis, cementing its importance in orthodontic practice. Bolton was a graduate of the University of Washington, where he completed both his dental and orthodontic training. He was a member of the first dental class (1950) and the first orthodontic class (1952) at the university.

A Boley gauge is traditionally the instrument of choice for measuring the widths of each tooth. However, in 1995, Shellhart et al. demonstrated that a Vernier caliper could also be used as an alternative for measuring mesiodistal widths in Bolton Analysis. Over the years, various other tools have been tested, including measurement from photocopies and the use of a traveling microscope, but these methods did not yield consistent or reliable results.

More recently, the advent of digital calipers from companies such as OrthoCAD has allowed for more accurate and efficient measurements of the mesiodistal widths of the teeth, improving the overall reliability of Bolton Analysis in contemporary orthodontic practice.

Analysis

Bolton Analysis consists of two primary analyses:

1. Overall Analysis – This analysis measures the sum of the mesiodistal widths of all 12 mandibular teeth (from the first molar to the first molar) and compares this value to the sum of the 12 maxillary teeth. The overall ratio is known to be 91.3%. If the ratio is greater than 91.3%, it indicates that the mandibular teeth are larger than the maxillary teeth; if it is smaller, the mandibular teeth are smaller than normal.

2. Anterior Analysis – This analysis measures the sum of the mesiodistal widths of the six front mandibular teeth (incisors and canines) and compares this value to the corresponding maxillary teeth. The anterior ratio is typically 77.2%. As with the overall analysis, a ratio larger than 77.2% indicates that the mandibular teeth are larger than the maxillary teeth, while a ratio smaller than 77.2% suggests that the mandibular teeth are smaller than normal.

A deviation from these ratios is referred to as a Bolton Discrepancy. When a discrepancy exceeds a standard deviation of more than 2, it is considered statistically significant and may require orthodontic correction.

Drawbacks

One major drawback of Bolton Analysis is that the original sample used by Bolton in his 1958 study was composed exclusively of a Caucasian population. As a result, the overall and anterior ratios, as well as the standard deviations, may not be representative of other populations or ethnic groups. This limitation means that the Bolton ratios may not always be applicable to diverse patient populations, especially when considering racial and genetic variations in tooth sizes.

Another issue is that the sample Bolton used was composed of individuals with ideal malocclusion (perfect occlusion), which does not necessarily reflect the general population. Consequently, many modern populations show discrepancies compared to Bolton's established ratios, leading to higher-than-expected discrepancies in routine orthodontic assessments.

Furthermore, variations in tooth size and shape between individuals make it difficult to apply Bolton’s analysis universally. This is especially true in cases of mixed dentition or in patients with developmental anomalies.

See Also

• Malocclusion
• Orthodontics
• Occlusion
• Tooth eruption
• Orthodontic treatment planning
• Standard deviation

External Links

• Bolton Analysis in Practice
• Bolton’s Work in Modern Orthodontics