Tooth problems
You can find the sentence: “with progressing age a forward angulation of the front teeth of a horse occurs.” in nearly all literature that looks at the horse’s anatomy. Unfortunately we are not being told the reason for this occurance but the fact is merely stated. At this point it is quite interesting to know that this phenomenon does not occur on animals of the equine family living in the wild (for example mustangs).
The reason for these forward angulations is scarily simple: not enough abrasion!
As well as the molars the front teeth erupt into the mouth cavity at a rate of ca. 3mm per year and per jaw, which means an addition of 6 mm of tooth substance every year. Due to domestication and today’s feeding (soft, high in nutrient grass, pellets, grains; hay) the front teeth experience virtually no wear at all anymore. Because of this the front teeth become much longer in comparison to the molars and prevent a meeting of the chewing surfaces of the molars (occluding). To maintain the ability to still grind any feed between the chewing surfaces of the molars, the musculus masseter (chewing muscle, strongest muscle in the horse’s body) has to work unnaturally hard to make the molars meet. This causes temporo mandibular joint problems (tmj, jaw joint) as well as too much pressure on the front teeth. The front teeth experience out of centre applied chewing forces and are forced to the labial (towards the lip), which results in forward angulation!
To prevent these detrimental long-term damages, a complete dental treatment has to include a shortening of the front teeth until the balance between front teeth and molars is restored (once a year). It is not enough just to slightly straighten them with manual rasps (when front teeth have not been treated for a while). To ensure enough tooth substance reduction in regards to the balance of front teeth and molars the use of water cooled, electrical rotary instruments is unavoidable. The best results can be achieved with a diamond coated disc. The line created by the two rows of front teeth (upper and lower) also provides clues to a malocclusion (improper meeting of the teeth).
For example:
„Smile“ (concave line dividing upper and lower front teeth)
„Frown“ (convex line dividing upper and lower front teeth)
„diagonal“
Grinders - Molars
Another very important component of how the mouth is balanced is the diet. Horses evolved to graze with their heads down at ground level eating grasses for many hours a day. By altering their living and feeding conditions we alter the way their teeth wear: by forcing them to eat with their head up; providing short feeding times; feeding grains, chaffs and pelleted feeds. When we do this we must be aware of the effects these changes have on the horses dentition.
Horses also have another important anatomical difference from people. Their upper jaw, when viewed from the front, is wider than their lower jaw, and this means that the outer surface of the upper cheek teeth (closest to the cheeks) is unopposed, as is the inner (closest to the tongue) surface of the lower cheek teeth. The edges or cingulae of these teeth grow through the continual process of eruption but are not worn away and these form razor sharp points (similar to the teeth of a saw blade) along the arcade of teeth. When the horse eats it is forced to bring its cheeks into contact with these points.
Because the horse chews in a complicated four part cycle, not simply side to side or up and down, these points then act on the cheeks and tongue of the horse like a saw blade causing ulceration, cuts and abscessation if bacterial infection occurs. Dental problems do not only have an adverse effect on the horses head area but also the entire body and its functions (also see Symptoms). The upper and the lower jaw are locked into unhealthy and unnatural positions by abnormalities and create stiffness in for example the horse’s neck and back. This can even result in lameness. In addition to this the horse will deteriorate in general if dental problems are not treated. Due to overextended teeth the circular chewing movement is impaired and the feed is not being broken up into small enough particles and as a result cannot be digested fully. The result is malnutrition with all its known knock-on effects.