In this study 2 separate groups of horses were examined by kinematic analysis. In the first group with 5 horses the effects of two different methods of dental correction on the masticatory movements were evaluated. In a second group with 5 horses with dental problems it was tried to analyse the variations of the chewing cycles of horses before and after dental extraction(s). The general goal of both studies was to evaluate the potential(s) of kinematic analysis as a diagnostic tool for evaluation of the effectiveness of dental treatments.
The first group of horses consisted of 5 warmblood horses, 4 geldings and 1 mare, of different breeds and aged between 5 and 18 years. The horses had only mild cheek teeth pathology. Ten marker balls of 1 and 2 cm diameter respectively were glued to the skin with superglue at defined landmarks. The horses were fed from the ground with hay of standardised quality.
Kinematic measurements were performed once before routine dental treatment and three times afterwards following a standardised examination protocol. Masticatory movements were recorded with 10 high speed video cameras (120 Hz) (Motion Analysis System Corp.®) placed in a circle around the horse. Measurements were repeated on days 7, 21 and 28.
For the oral examination and following dental correction, the horses were sedated with detomidin-hydrochloride (Domosedan®), 0,02 mg/kg, i.v.
and butorphanol (Butomidor®), 0,01 mg/kg, i.v. All dental examinations and corrections were performed using a full mouth speculum, an endoscope, power rotating tools and hand floats. Pathological changes were charted using customary software.
The first therapy (method 1) consisted of the removal of sharp enamel edges and the correction of abnormalities of dental wear. Incisors were not corrected routinely. 18 months later the same group of horses was subjected to another routine dental treatment performed by other therapists. A different, more aggressive correction technique which also included correction of the incisors in all animals was used (method 2).
Data was tracked automatically with EVA 6.0 software. Analysis after data-tracking of each mandibular marker was performed according to NIEDERL (2007) Analysis was focused on marker nine. In a next step data of marker 9 was transformed using Matlab 7.0.1., separated and normalised. Further data processing was performed in Excel. For statistical calculations SPSS 12.0 was used. The data were tested on normal distribution by Kolmogorov-Smirnov-Test. The groups were compared using ANOVA for repeated measurements and T-Test for paired samples.
In this first study the only significant result for the group was that after the first treatment (day 7, method 1) the amplitude along the y-axis (latero-lateral mandibular movement) was reduced compared to the last measurement (day 21). A remarkable finding, though not significant for the group, was that in four out of five horses, the rostro-caudal mandibular movement (x-axis) was significantly reduced at the last measurement compared to the first measurement following treatment with method 2. The analysis of the chewing motions of individual horses showed a multitude of significant differences. Based on our current knowledge of equine mastication the interpretation of our results remained insufficient. Further studies and a more profound knowledge of equine mastication are encouraged to allow a profound interpretation of kinematic findings.