A comparison of three methods to accurately measure root length

Area of Science:

• Dental Radiology
• Orthodontic Treatment Outcomes
• Biomedical Imaging

Background:

• Root shortening is a common concern following orthodontic treatment, impacting dental fields and legal contexts.
• Periapical radiography is the standard method for assessing root length, though inaccuracies can occur.

Purpose of the Study:

• To evaluate how angular variations between teeth and radiographic film affect tooth length measurements.
• To compare different methods for accurate root length measurement on radiographs.
• To identify optimal reference points on teeth for precise root length calculations.

Main Methods:

• An acrylic model of a maxillary central incisor with five reference amalgam dots was used.
• Radiographs were taken at four different film-to-tooth angulations using a specialized jig.
• Root and crown lengths were measured directly from the model and from scanned radiographic images.

Main Results:

• Angular changes between the tooth model and the film significantly influenced the measured tooth length.
• The midpoint between the mesial and distal cementoenamel junction (CEJ) points (median CEJ) proved to be the most reliable reference point.
• Accurate root length calculations were achieved using the median CEJ with the rule-of-three formula.

Conclusions:

• Radiographic angulation is a critical factor affecting the accuracy of orthodontic root length measurements.
• The median CEJ reference point offers a more precise method for calculating root lengths from radiographs.
• This finding aids in more reliable assessment of root shortening in orthodontic patients.