Biomechanical Evaluation of Equine Masticatory Action: Position and Curvature of Equine Cheek Teeth and Age‐Related Changes

Abstract

The equine cheek tooth battery is part of a very dynamic system. The aim of this study was to investigate whether the curvature and position of the teeth are also involved in such dynamical processes. The alveolar crest was labelled with a radiodense marker (48 cadaver heads, 15 skulls) and laterolateral radiographs were taken. Then a geometrical method was elaborated to determine a cheek tooth's curvature and its position by means of specific angles. This method respects the remarkable changes of the equine dentition throughout life by considering two items: (1) the alveolar crest was taken as a constant landmark, (2) the central axis of the curved dental crown was determined by calculation of a linear regression equation. This equation considered several geometrically determined points on the curved dental crown which had been marked in the radiographs. Our study yielded the following results: Mandibular cheek teeth became more curved with age, but their positions (represented by the so-called mesio-occlusal angle between tooth and alveolar crest) did not change significantly. In maxillary cheek teeth, however, the mesio-occlusal angle became larger with age (indication of change of dental position), while their curvature did not change. Even though changes of the dental position were not always statistically significant, they are discussed as being biologically/functionally relevant. The mandibular anticlinal tooth, i.e. the tooth positioned at a mesio-occlusal angle of about 908, was not in contact with the maxillary anticlinal tooth. Interestingly, the maxillary anticlinal tooth is known to cause most clinical dental problems.

Biomechanical evaluation of the equine masticatory action: Calculation of the masticatory forces occurring on the cheek tooth battery

“…This wire was supposed to serve as a landmark on the ensuing digital radiographs taken in a laterolateral technique. Each of the radiographs of the cadaver heads and of the skulls was converted into a JPEG file and imported to the Adobe Photoshop (Version 7.0) software program (for details see Huthmann et al, 2008a). In the following, several auxiliary lines were added to the radiographs to facilitate the ensuing measuring process (see Fig.…”

Scintigraphic evaluation of cheek teeth in clinically sound horses

“…20 21 Another factor that plays an important role in equine masticatory biomechanics is the curvature of equine CT, which increased from rostral to caudal. 20 Teeth 09 (maxillary) and 07 (mandibular) were the anticlinal teeth, that is, these teeth stood at an angle of nearly 90°, which predisposed them for higher loading and stress compared with the other teeth. 20 This could explain the peak RU in these teeth.…”

“…This finding could be attributed to the biomechanics of the masticatory process. It has been reported that the forces generated during equine mastication influence the teeth, as well as the periodontium and the jaw bones, where the forces increased from rostral to caudal 20 21 . Another factor that plays an important role in equine masticatory biomechanics is the curvature of equine CT, which increased from rostral to caudal 20 .…”

“…It has been reported that the forces generated during equine mastication influence the teeth, as well as the periodontium and the jaw bones, where the forces increased from rostral to caudal 20 21 . Another factor that plays an important role in equine masticatory biomechanics is the curvature of equine CT, which increased from rostral to caudal 20 . Teeth 09 (maxillary) and 07 (mandibular) were the anticlinal teeth, that is, these teeth stood at an angle of nearly 90°, which predisposed them for higher loading and stress compared with the other teeth 20 .…”

Electromyographic evaluation of masseter muscle activity in horses fed (i) different types of roughage and (ii) maize after different hay allocations

“…Non‐invasive EMG recordings of masseter muscle activity may be used to investigate different clinical conditions. For example, Huthmann et al. (2008) showed that masticatory forces decreased as horses aged; whether these changes affect masseter muscle activity remains to be demonstrated.…”