Brief communication: correcting overestimation when determining two-dimensional occlusal area in human molars

Area of Science:

• Anthropology
• Paleontology
• Forensic Anthropology

Background:

• The robustness index (RI) is a common method for estimating tooth occlusal area.
• RI calculations consistently overestimate tooth area because teeth are not rectangular.
• Overestimation by RI varies due to differences in tooth shape, particularly in molars.

Purpose of the Study:

• To investigate how tooth shape influences RI overestimations.
• To develop improved methods for accurately estimating molar occlusal area.
• To introduce a new index for more precise tooth area measurements.

Main Methods:

• Classified 120 molars into six shape groups based on hypocone/hypoconulid expression.
• Utilized ANOVA to analyze RI overestimation differences across shape categories.
• Developed and validated regression-based correction formulae to create an adjusted robustness index (ARI).

Main Results:

• RI overestimations averaged approximately 20% and varied significantly by molar shape.
• Maxillary molars with large hypocones and mandibular molars lacking hypoconulids showed less overestimation.
• The developed correction formulae reduced overestimation to an average of 0.5% in validation, irrespective of tooth shape.

Conclusions:

• The adjusted robustness index (ARI) provides a more accurate estimation of molar occlusal area than the traditional RI.
• ARI minimizes overestimation errors, making it a more reliable tool for dental anthropology and related fields.
• The study recommends the adoption of ARI for future research involving molar occlusal area estimations.