The dental pulp of horses appears to retain its juvenile status throughout adulthood, research findings suggest, which explains its unchanged ability to produce high amounts of dentin.
Horses are hypsodont animals, meaning their teeth continually erupt throughout their lives. In turn, they are worn away by grinding food.
To remain healthy and functional, the hysodont teeth have to produce lifelong large amounts of hard dentin to prevent painful exposure of the pulp.
Assuming that equine teeth lose 3–4 millimetres of dentin at their grinding surface each year, the compensatory production of a similar amount of dentin is required.
Thus, a production rate of subocclusal dentin of about 8–10 microns per day (a micron is equal to 0.001 millimetres) is necessary, even in older horses.
Researchers with Germany’s Justus-Liebig-University Giessen set out in a just-published study to learn more about the factors that guarantee the lifelong high productivity of equine pulp.
Ten incisors and ten cheek teeth from seven adult horses, aged 5 to 24 years, and from five foals, were evaluated.
They found that, independent of age, the equine dental pulp featured constant layers of predentin and odontoblastic cells, as well as soft connective tissue, composed of a cellular fibrous matrix, in which blood vessels and nerve fibers were embedded.
“As a result of the progressive deposition of newly formed dentin, the layer of dentin became thicker with age, and the size of the pulp chamber decreased,” Jessica Roßgardt and her fellow researchers reported in the journal Veterinary Sciences.
In contrast to brachydont (low crown) teeth, such as those found in humans, the characteristics of the odontoblastic layer and the width of the predentin layer did not change with age.
“Therefore, it is assumed that the equine pulp tissue retained their juvenile status, which explains its unchanged ability to produce high amounts of subocclusal dentin.”
This, they said, is presumably triggered by the constant biomechanical forces generated by tooth wear.
“These preliminary, but clinically significant, findings are worthy of further investigation in order to identify strategies for equine-specific endodontic therapies,” they said.
Such treatments might take advantage of the high productivity of equine pulpal cells to stimulate the production of intra-pulpal dentinal bridges to demarcate diseased pulpal areas for vital pulp regions.
“However, access to and manipulation within equine dental pulp might be complicated due to the delicate dimensions of the equine pulp system elucidated in this study,” they said.
The study team comprised Roßgardt, Laura Beate Heilen, Kathrin Büttner, Jutta Dern-Wieloch, Jörg Vogelsberg and Carsten Staszyk, all with Justus-Liebig-University Giessen.
Roßgardt, J.; Heilen, L.B.; Büttner, K.; Dern-Wieloch, J.; Vogelsberg, J.; Staszyk, C. The Equine Dental Pulp: Histomorphometric Analysis of the Equine Dental Pulp in Incisors and Cheek Teeth. Vet. Sci. 2022, 9, 261. https://doi.org/10.3390/vetsci9060261