Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns

Abstract

The angle encompassed between opposing incisors in horses is assumed to decline with age. Previous studies merely consider the overall profile view of clinical crowns presuming a generalized angle, neglecting potential tooth position-dependent differences. Cephalometric measurements from 3D computed tomographic thick-slab reconstructions of single incisors within a global reference frame were used to determine clinical crown interincisal angulation (IIA) of 48 horses. Based on predefined dentoalveolar landmarks, IIA was defined as the angle enclosed by the respective labial axis of the clinical crown (LACC). A measurement repeatability analysis was conducted including a comparison of third incisor teeth IIA with data obtained by cephalometric implementation of previously described landmarks for third incisor teeth (lingual/palatal border). The age-related angle course and differences between tooth positions were investigated considering LACCs of permanent incisors. Determining IIA by LACCs exhibited a high level of reproducibility applying for all tooth positions (mean coefficient of variation = 0.65 %; mean SD ± 0.89°). The comparison method for third incisor teeth revealed two times higher mean dispersion of repeated measurements, P = 0.017. A non-linear model slightly increased predictability of angular changes over time as against linearity assumption. The angle decline was more distinctive in younger horses and appears to approach a final value in older ones. Third incisor teeth exhibited significantly higher angle decline compared to first and second incisor teeth, P < 0.0001. According to the results, age determination of horses using clinical crown IIA is not recommended. Rather, 3D cephalometry may provide a promising tool to determine interdental and dentofacial angles of distinct tooth positions in health and disease.

Comparison of Computed Tomography Assisted 3D Cephalometric Measurements in Straight Egyptian Arabian and Thoroughbred Horses

“…Previous research has shown that horses 8 to 15 years of age typically have IIA of approximately 90°, which is consistent with the SEAR findings in the current study. 14,15 With the mean age of the TB group (7.47 years) being significantly younger than the mean age of the SEAR group (10.4 years), it is logical to assume that this difference in age could explain the difference in IIA between the 2 breeds. However, it is interesting to note that although it is widely accepted that IIA decreases with age, the results of the current study did not find age to have a significant effect on IIA ( P = 0.12).…”

“…1 A CT 3D cephalometric approach has also been investigated for the purpose of age determination in horses by measuring the angulation between incisor clinical crowns but has not been found to be a reliable tool for this purpose. 14…”

Equine odontoclastic tooth resorption and hypercementosis: Investigating individual incisor disease patterns using radiological classification

“…rotating movement in their alveoli. 28 However, there are no data on the distribution of masticatory forces within the incisor arcades.…”

“…A recent CT study demonstrated that opposing corner incisors have the highest annual angle decline, i.e. rotating movement in their alveoli 28 . However, there are no data on the distribution of masticatory forces within the incisor arcades.…”

The facultative human oral pathogen Prevotella histicola in equine cheek tooth apical/ periapical infection: a case report

“…Standing computed tomography (CT) of the head using a big bore sliding gantry (Somatom Sensation Open; Siemens Healthcare, Forchheim, Germany) was performed as previously described [ 37 , 38 ]. The radiological assessment, using Syngo imaging software (Siemens Healthcare), comprised three-dimensional volume rendering, multiplanar reconstructions, and orthogonal reconstructions.…”