Enamel thickness and the helicoidal occlusal plane

Area of Science:

• Paleoanthropology
• Dental Morphology
• Biomechanics

Background:

• The human occlusal plane exhibits a complex helicoidal form, influenced by tooth wear and eruption patterns.
• Understanding enamel thickness and dentine horn morphology is crucial for reconstructing masticatory biomechanics and evolutionary adaptations.

Purpose of the Study:

• To investigate the relationship between enamel thickness distribution, dentine horn heights, and the helicoidal occlusal plane in human maxillary molars.
• To analyze anteroposterior changes in these dental features and their implications for molar function and evolution.

Main Methods:

• Analysis of 38 unworn and 6 worn human maxillary molars (M1, M2, M3) from a Slavic necropolis.
• Sectioning of molars perpendicular to the cervical margin to measure enamel thickness and dentine horn heights.
• Application of uni- and multivariate statistical analyses to assess dimensional changes and their correlation with occlusal wear.

Main Results:

• Enamel thickness increases from anterior to posterior along the occlusal basin, correlating with the helicoidal wear pattern.
• Second and third molars exhibit thicker enamel under the paracone's lingual slope (Phase I) compared to the protocone's buccal slope (Phase II).
• Dentine horn heights change anteroposteriorly, supporting the role of axial tooth inclination in developing the helicoidal occlusal plane.

Conclusions:

• The helicoidal occlusal plane is a structural feature of the human orofacial skeleton, evidenced by enamel distribution patterns.
• Molar enamel thickness distribution adapts to functional demands, with a trend towards specialization from shearing (anterior) to crushing/grinding (posterior).
• These findings contribute to understanding the functional morphology and evolutionary trajectory of human molars.