The Equine Dental Pulp: Histomorphometric Analysis of the Equine Dental Pulp in Incisors and Cheek Teeth

Abstract

To maintain a healthy and functional status, equine hypsodont teeth have to produce lifelong large amounts of subocclusal dentin to prevent occlusal pulp exposure, which is caused by occlusal wear. To examine the cyto- and histological components that guarantee the lifelong high productivity of equine pulp, a limited number of ten incisors and ten cheek teeth from seven adult horses (aged 5 to 24 years) and five foals were sampled for preliminary histomorphometric and histomorphological evaluations. Independently 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. In contrast to the brachydont teeth, the morphological 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. These preliminary, but clinically significant, findings are worthy of further investigation in order to identify strategies for equine-specific endodontic therapies.

Isolation and cultivation as well as in situ identification of MSCs from equine dental pulp and periodontal ligament

“…This might lead to the assumption of a steady process of lifelong odontoblast regeneration in unaffected equine teeth, which resembles the process in brachydont teeth after cavity preparation. Furthermore, the results support the findings of Roßgardt et al (27) that the equine dental pulp remains lifelong in an immature highly productive status and contains a subodontoblastic supportive zone to ensure the continuous production of dentin.…”

“…Schrock et al (31) describe a starting reduction of incisor length at an age of 13-15 years. Since we found no obvious difference in cell growth in horses aged 13-24 years, a key factor for the reduction of obtained pulpal tissue in aged horses might be their smaller pulp cavity (27,32). Even the conditions of the teeth and donor seemed to play a role since an infected tooth or a sepsis due to colic caused bacterial contamination during cultivation.…”

“…During tissue preparation for cell-isolation, additional section planes of the incisors were cut and fixed in 10% buffered formalin (pH 7). After fixation, the sections were watered, further trimmed with a diamond-coated, water-cooled microband saw, and decalcified on a platform shaker (Polymax 1040, Heidolph Instruments, Schwabach, Germany) in buffered EDTA (ethylenediaminetetraacetate) for 6 weeks as previously described by Roßgardt et al (27). Following this decalcification process, the samples were trimmed using a scalpel to minimize section size but receive both PDL and pulp within one section.…”

“…Subsequently, the samples were rinsed in tap water and stored in PBS overnight. Paraffin embedding, sectioning, and staining were implemented according to Roßgardt et al (27). Toluidine blue staining was performed according to a standard protocol to evaluate the sections under a light microscope (Leica DM2500, Leica Microsystems GmbH).…”

Micro-CT and histological examination of accessory canals in 34 equine cheek teeth

“…Many authors have described in detail the dynamic anatomy of the pulp system in equine cheek teeth and incisors. Studies conducted with the use of dental sectioning ( 1 – 5 ), histology ( 1 – 3 , 5 – 8 ), radiography ( 1 , 5 , 6 , 9 ), (micro) computed tomography imaging (CT) ( 3 – 7 , 10 , 11 ) and Magnetic Resonance Imaging (MRI) ( 9 ) revealed an intricate, ever-changing system of interconnected pulp horns, pulp canals and pulp chambers ( 12 , 13 ). However, besides a brief mention ( 7 ), none of these papers focused on details of the apex of equine cheek teeth in form of an apical delta formation and/or accessory root canals.…”