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Uneven distribution of enamel in the tooth crown of a Plains Zebra (Equus quagga).

Winkler DE, Kaiser TM - PeerJ (2015)

Bottom Line: They have to be partially worn to expose enamel ridges which can then act as shear-cutting blades to break the food down.We use the Plains Zebra (Equus quagga) as a hypsodont, herbivorous model organism to investigate how initial wear of the tooth crown is controlled by underlying structures.We find that the enamel proportion is smaller at the apical half of the tooth crown in all upper tooth positions and suggest that lower enamel content here could promote early wear.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center of Natural History (CeNak), University of Hamburg , Hamburg , Germany.

ABSTRACT
Unworn teeth of herbivorous mammals are not immediately functional. They have to be partially worn to expose enamel ridges which can then act as shear-cutting blades to break the food down. We use the Plains Zebra (Equus quagga) as a hypsodont, herbivorous model organism to investigate how initial wear of the tooth crown is controlled by underlying structures. We find that the enamel proportion is smaller at the apical half of the tooth crown in all upper tooth positions and suggest that lower enamel content here could promote early wear. Besides this uneven enamel distribution, we note that the third molar has a higher overall enamel content than any other tooth position. The M3 is thus likely to have a slightly different functional trait in mastication, resisting highest bite forces along the tooth row and maintaining functionality when anterior teeth are already worn down.

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Enamel content per section and tooth position.(A) Relative enamel content per section and tooth position. Proportions are calculated using the whole tooth volume with all dental tissues (enamel, cementum, dentin). (B) The value of enamel versus dentin expressed as the quotient from enamel/dentin per section and tooth position.
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fig-4: Enamel content per section and tooth position.(A) Relative enamel content per section and tooth position. Proportions are calculated using the whole tooth volume with all dental tissues (enamel, cementum, dentin). (B) The value of enamel versus dentin expressed as the quotient from enamel/dentin per section and tooth position.

Mentions: Data on enamel content in relation to the whole tooth volume and the whole volume without cementum are given in Table 1. Though distribution of enamel content per section was variable between teeth, it was consistently smallest in Section 1 (the most apical section) for all tooth positions when total volume was considered. In relation to the tooth model without cementum, however, either Section 1 or Section 2 had the lowest enamel proportions. This shifted ratio results from a higher cementum deposition at the apex of the tooth. For the full tooth model, Section 4 had the highest enamel proportions within each tooth position. When cementum was left out, either Section 3 or Section 4 had the highest relative enamel content (compare Table 1). It is notable that M3 was composed of more enamel than all other teeth (>7% higher relative enamel content than all other tooth positions). This is well expressed in the enamel/dentin-ratio (Fig. 4B). From P2 to M2, each section except P4 Section 4 contained less enamel then dentin. For the M3, however, this ratio reversed as each section contained more enamel than dentin.


Uneven distribution of enamel in the tooth crown of a Plains Zebra (Equus quagga).

Winkler DE, Kaiser TM - PeerJ (2015)

Enamel content per section and tooth position.(A) Relative enamel content per section and tooth position. Proportions are calculated using the whole tooth volume with all dental tissues (enamel, cementum, dentin). (B) The value of enamel versus dentin expressed as the quotient from enamel/dentin per section and tooth position.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4465953&req=5

fig-4: Enamel content per section and tooth position.(A) Relative enamel content per section and tooth position. Proportions are calculated using the whole tooth volume with all dental tissues (enamel, cementum, dentin). (B) The value of enamel versus dentin expressed as the quotient from enamel/dentin per section and tooth position.
Mentions: Data on enamel content in relation to the whole tooth volume and the whole volume without cementum are given in Table 1. Though distribution of enamel content per section was variable between teeth, it was consistently smallest in Section 1 (the most apical section) for all tooth positions when total volume was considered. In relation to the tooth model without cementum, however, either Section 1 or Section 2 had the lowest enamel proportions. This shifted ratio results from a higher cementum deposition at the apex of the tooth. For the full tooth model, Section 4 had the highest enamel proportions within each tooth position. When cementum was left out, either Section 3 or Section 4 had the highest relative enamel content (compare Table 1). It is notable that M3 was composed of more enamel than all other teeth (>7% higher relative enamel content than all other tooth positions). This is well expressed in the enamel/dentin-ratio (Fig. 4B). From P2 to M2, each section except P4 Section 4 contained less enamel then dentin. For the M3, however, this ratio reversed as each section contained more enamel than dentin.

Bottom Line: They have to be partially worn to expose enamel ridges which can then act as shear-cutting blades to break the food down.We use the Plains Zebra (Equus quagga) as a hypsodont, herbivorous model organism to investigate how initial wear of the tooth crown is controlled by underlying structures.We find that the enamel proportion is smaller at the apical half of the tooth crown in all upper tooth positions and suggest that lower enamel content here could promote early wear.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center of Natural History (CeNak), University of Hamburg , Hamburg , Germany.

ABSTRACT
Unworn teeth of herbivorous mammals are not immediately functional. They have to be partially worn to expose enamel ridges which can then act as shear-cutting blades to break the food down. We use the Plains Zebra (Equus quagga) as a hypsodont, herbivorous model organism to investigate how initial wear of the tooth crown is controlled by underlying structures. We find that the enamel proportion is smaller at the apical half of the tooth crown in all upper tooth positions and suggest that lower enamel content here could promote early wear. Besides this uneven enamel distribution, we note that the third molar has a higher overall enamel content than any other tooth position. The M3 is thus likely to have a slightly different functional trait in mastication, resisting highest bite forces along the tooth row and maintaining functionality when anterior teeth are already worn down.

No MeSH data available.


Related in: MedlinePlus