Studies on Age-Related Changes in Equine Cheek Teeth Angulation and Dental Drift.

Tiziana Liuti,Carola R Daniel,Padraic Martin Dixon,Richard J M Reardon

doi:10.3389/fvets.2021.804061

Abstract

BackgroundCheek teeth (second through fourth premolars and first through third molars) diastema is a common and painful equine disorder caused by the absence of effective tight interdental contact between these teeth. Limited objective information is available on the angulation of equine cheek teeth that control dental drift or on mesial or distal equine cheek teeth drift that should normally prevent this disorder.ObjectivesTo measure the angulation of the mesial and distal cheek teeth in horses of different ages, quantify age-related cheek teeth mesial and distal dental drift, and measure the cheek teeth row length in horses of different ages.Study DesignRetrospective review of computed tomographic images of equine heads.MethodsCase details and CT images from clinical equine cases that had undergone standing CT head examination were collated.Three sets of measurements were acquired from each head. “Head size” calculated as the distance between the caudal aspect of the orbit and the caudal aspect of the naso-incisive notch was used to standardize measurements in different sized heads. The length of the cheek teeth rows measured from the mesial aspect of the Triadan 06 occlusal surface to the distal aspect of the Triadan 11 occlusal surface. The rostro-caudal (antero-posterior) position and angulation of the mandibular and maxillary Triadan 06 and 11 teeth were measured in relation to reference lines drawn on CT images.ResultsSignificant mesial drift occurred in the maxillary and mandibular Triadan 11s. Despite their distal angulation, the upper and lower Triadan 06s also drifted mesially. The mean angulation of Triadan 06 and 11 mandibular teeth (17.8 and 26.2°, respectively) was almost double that of maxillary teeth (9.2 and 13.3°, respectively) with both Triadan 11s having greater angulation than the 06s. Cheek teeth angulation only significantly decreased in the mandibular 06s. Cheek teeth arcade lengths decreased with age, but these decreases were not significant.Main LimitationsLimitations include the relatively small sample size.ConclusionsIn the population of horses used for this study, age related mesial drift occurred in both Triadan 06 and 11s, and the angulation of these teeth did not decrease with age in most arcades.

Highlights

Mammalian teeth within a complete dental arch normally drift in a mesial direction with age
Mesial drift is needed by equine teeth because their long crowns taper in toward their apices, making the clinical crowns in older horses progressively smaller in a mesio-distal direction following normal eruption and occlusal wear
This study confirms the presence of age-related mesial drift of the caudal (Triadan 11s) equine maxillary cheek teeth previously quantified by Liuti et al [3] with a mesial drift of 9 mm found between the 16 y.o. group in this study

Summary

Introduction

Mammalian teeth within a complete dental arch normally drift in a mesial direction (toward the midline, i.e., between the first incisor teeth) with age This normal, posteruptive dental movement is to compensate for normal interproximal dental wear at contact areas of adjacent teeth and so prevent abnormally wide interproximal spaces (diastemata) from developing. Mesial drift is needed by equine teeth because their long (clinical and reserve) crowns taper in toward their apices, making the clinical crowns in older horses progressively smaller in a mesio-distal direction following normal eruption and occlusal wear. This feature makes equine teeth more prone to developing diastemata with age (termed senile diastemata) [2]. Limited objective information is available on the angulation of equine cheek teeth that control dental drift or on mesial or distal equine cheek teeth drift that should normally prevent this disorder

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