Is the Bolton analysis performed by ClinCheck real?

We all remember our post-graduate years when we had to measure the size of each tooth on the plaster models with the caliper in order to calculate the Bolton discrepancy. A tedious job like no other, in which we spent hours and hours.

Fortunately, technology has greatly facilitated this work. Nowadays, planning softwares have the necessary tools to calculate the discrepancy between the size of the teeth of both arches. However, these measurements are not always as accurate as we might think. In the process of measuring teeth, there are 3 main factors that can affect their reliability.

Factors affecting its reliability

• Access to the teeth anatomy. Depending on the malocclusion we scan, we will not have the same ability to obtain accurate records of the teeth. For example, in a patient with diastemas, the scanner will be able to capture the entire tooth structure more accurately, while in a patient with severe crowding and rotations, part of the tooth shape will be "invented" or estimated by the program.
• The difficulty in locating a clear reference to determine the mesial and distal side of the tooth. This problem may appear in teeth with irregular anatomy or interproximal wear.
• Inconsistent measurement protocol. If the parameters for these measurements are not well calibrated, the risk of inaccuracy increases.

As Invisalign is the most widely used brand of aligners globally, the existing studies to determine the accuracy of the Bolton analysis have been done with the ClinCheck Pro software. From those studies, the first conclusion we can draw is that the ClinCheck measurement tool is not 100% accurate. However, in each of the studies they use different measurement methods: in one of them they use a 3D optical profilometer, which has an accuracy of microns, and in the other study they compare the ClinCheck measurements with the traditional human measurement method. As might be expected, the results of both studies were completely different.

• In the study where they used the optical profilometer , they found that the ClinCheck had a tendency to underestimate tooth size, and this difference was higher in the posterior teeth.
• In the study where they made manual measurements , they concluded that the ClinCheck provided higher mesiodistal values than the clinician's values, with the highest difference in molars as well.

How this lack of accuracy can affect tooth size measurement?

We have to review the software from a more critical point of view, we cannot "believe" in the Bolton analysis that the ClinCheck calculates. It can be taken as a reference to know if there is a lack or excessive dental material in one arch, but assuming that these measurements are not exactly the same as the real teeth.

On the other hand, clinically, discrepancies between the estimated and the actual interproximal anatomy can lead to undesired contacts between the teeth. Fortunately, there is an easy solution to this problem : Verify at every appointment the interproximal contact points and use IPR strips to alleviate the areas where strong contacts exist.

Adobes Martin M et al. Reliability of Tooth Width Measurements Delivered by the ClinCheck Pro 6.0 Software on Digital Casts: A Cross-Sectional Study. Int J Environ Res Public Health. 2022 Mar 17;19(6):3581.

Shailendran A et al. Accuracy and reliability of tooth widths and Bolton ratios measured by ClinCheck Pro. Am J Orthod Dentofacial Orthop 2022;161:65-73.