Quantification of the Dental Morphology of Orangutans

Orangutans are believed to have close biological affinities to humans. Teeth being the hardest tissue provide useful information on primate evolution. Furthermore, knowledge of the pulp chamber and root canal morphology is important for dental treatment. A female Bornean orangutan and a Sumatran male orangutan skull were available for this study. Both of their dentitions, comprising 50 teeth, were scanned employing the cone-beam computed tomography for both metrical and nonmetrical analyses. Measurements included tooth and crown length, root length, enamel covered crown height, root canal length (posterior teeth), length of pulpal space (anterior teeth), and root canal width. Nonmetrical parameters included number of canals per root, number of foramina in each root, and root canal morphology according to Vertucci’s classification. It was found that the enamel covered crown height was the longest in the upper central incisors although the canine was the longest amongst the anterior teeth. Both the upper premolars were three-rooted while the lower second premolar of the Sumatran orangutan was two-rooted, with two foramina. The mandibular lateral incisors of the Bornean orangutan were longer than the central incisors, a feature similar to humans. In addition, secondary dentine deposition was noticed, a feature consistent with aged humans

The mean distance between the lingual nerve and the 2 anatomical landmarks.

<p>The mean distance between the lingual nerve and the 2 anatomical landmarks.</p

The pattern of terminal branching of the lingual nerve.

<p>The pattern of terminal branching of the lingual nerve.</p

Mean horizontal and vertical distances of lingual nerve from the third molar bone crest.

<p>Mean horizontal and vertical distances of lingual nerve from the third molar bone crest.</p

The diagram illustrates the measuring of the extent of overlap between the lingual nerve and the submandibular duct (distance a-b).

<p>The diagram illustrates the measuring of the extent of overlap between the lingual nerve and the submandibular duct (distance a-b).</p

The location where the looping of the lingual nerve over the submandibular duct ended.

<p>The location where the looping of the lingual nerve over the submandibular duct ended.</p

Measurement of incisive foramen (blue line), nasal foramen (red line), incisive diameter (green line), and the incisive foramen location (yellow line).

<p>Measurement of incisive foramen (blue line), nasal foramen (red line), incisive diameter (green line), and the incisive foramen location (yellow line).</p

Distribution showing alveolar bone shape anterior to the incisive canal in subjects of different gender and ethnicity.

<p>Distribution showing alveolar bone shape anterior to the incisive canal in subjects of different gender and ethnicity.</p

Representative images showing different classifications of the direction and course of the incisive canal.

<p>Representative images showing different classifications of the direction and course of the incisive canal.</p

Differences in average anterior maxillary bone thickness between those aged above and below 45 years.

<p>* Independent <i>t-test</i>.</p><p>Differences in average anterior maxillary bone thickness between those aged above and below 45 years.</p