Addressing the incisors first is the key to balancing the mouth by setting up proper rotation of the temporomandibular joint. Photo by David Ulloa © 2004 Valeo Films Inc.
Natural Balance in the Equine Mouth
It seems that we can all understand how nature intended balance to be for the equine foot. As the horse roamed its domain, excess growth wore away naturally by herd movement across the terrain. This natural wear by lifestyle and environment is also true of the equine mouth, though perhaps it has been overlooked for a long time. Out of sight, out of mind. The concept of 'form to function - function to form' is well understood these days. What I am going to share with you in this article is not just my opinion, but also that which seems to fit the horse naturally.
In its natural state, the horse would graze 14-18 hours a day on grasses containing silicas, wearing or abrading the teeth in such a manner that the front teeth wear at the rate of eruption. These front teeth, or incisors, as they are called, are the key to balance in the mouth. The length and angle of the incisors at age 5 are meant to remain that way throughout the lifetime of the horse. It is at the age of 5 that the incisors of our domestic horses (unable to graze constantly) will begin to exceed their appropriate length and angle. This is the beginning of abnormal pressure and rotation of the TMJ ( Temporo Mandibular Joint), the joint where the jaw hinges to the skull. The rotation of this joint, which is dictated by the incisors, in turn dictates the wear pattern of the molars. So the point of equine dentistry is to address the cause, not treat the symptoms, by maintaining a natural length and angle of the incisors, first and foremost. Balancing the rest of the mouth, including the molars, cannot be accomplished without proper balance in the front of the mouth.
Left: speculum open; Right: Speculum closed. The speculum assists the horse in maintaining an open mouth to receive dentistry. If the incisors are not balanced first, the speculum plates - rigidly level unto themselves - impose imbalance upon the back of the mouth.
Equine dentists use an instrument called a speculum to assist the horse in maintaining an open mouth to receive dental examination and treatment. It looks very much like a headstall, with an adjustable mouthpiece that sits just inside the horse's mouth with two metal plates for the upper and lower front teeth to rest on. This instrument must be opened and closed throughout work, minimizing any stress to the TMJ. If the speculum is left open for more than a few minutes at a time, it puts stress on the TMJ and on the horse. (Some horses are already in a great deal of discomfort, and this will exaggerate the discomfort.) These speculum plates are level unto themselves, so as they open the horse's mouth, any imbalance in the incisors will then be imposed upon the molar tables (the contacting surfaces of the upper and lower molars), causing the illusion of an imbalance originating in the molar area. Because the TMJ has approximately ¼' of 'play' in it, one can easily mistake the molars as the origin of the imbalance when in fact it is the incisors, at the opposite end of the mouth. This is why it is so critical to start with the incisors first.
Various imbalances of the incisors (clockwise from upper left): Correct, Wedged, Verted Curve, Inverted Curve. Whether complete balance restoration can be accomplished in one visit or not depends on the severity of the imbalance. Incisor work performed first is a must to insure speculum balance while addressing molars.
The incisors and their angles, the angle of the TMJ, and the molar tables' angles all must be taken into consideration when a dentist balances the horse's mouth. Many of today's equine dentists apply centric, or centered, alignment to the mouth; that is, applying a static 'leveling' standard to every equine mouth they treat. This will not address any asymmetry of the face and head. Addressing asymmetries is necessary to establish anatomical alignment of that individual's mouth, and therefore establish balance according to the whole horse.
Mastication, which can also be accomplished by a simple cue, reveals the true biomechanical range of the jaw.
The focus common among dentists currently is merely occlusion. This means, simply, the meeting, or flush contact, of upper and lower tooth-on-tooth surfaces. However, because of the adaptable nature of the equine, occlusion is present in all horses even before dentistry is applied. So it should be up to the dentist to anatomically align the mouth, so that it fits the individual to its optimum range.
The focus of equine dentistry should be anatomical balance - reestablishing proper biomechanics to the horse's jaw, by adjusting molar table surfaces and obstructions, correcting angles, and restoring range of motion in the jaw. The tongue rotates in the opposite direction to that of the jaw. The combined efforts of the two are what move the food bolus gradually from front to back in its only trip through the mouth. This being said, if the length and angle of the incisors vary from what nature intended, they cause the jaw to rotate in a more vertical motion - up and down (when looking at the incisors from the front), rather than from side to side, preventing thorough chewing and lessening digestion efficiency.
You would think that losing any biomechanical ability in such an important moving part would be rather disruptive; but, because of the small-particle processed feeds and concentrated rations we give our horses, we see very little difference in weight gain or loss in even the most serious mouth imbalances. The need to balance the equine mouth is visible, however, as a distorted way of travel, as well as impaired motion of the jaw. Jaw motion is directly equal to the motion of the horse's entire body - in all directions.
A popular but questionable practice in equine dentistry today is the "bit seat", a procedure that removes healthy tooth substance from a critical support area.
So, how do we check for biomechanics of the jaw? Rather than pushing the closed jaw from one side to the other (which most people are familiar with), you can properly check the horse by cueing him to contract his own masseters (muscles that control the jaw), which provides a demonstration of the true biomechanical range of the jaw. (Consider this: if pushing the closed jaw back and forth worked, human dentists would use it on us to check the surface to surface contact of our teeth, rather than the traditional carbon paper and 'bite down' technique.) The horse can be cued by inserting fingers into the side of the mouth (the safe space where there are no teeth - use caution!), initiating a chewing motion, a reflex response. Numerous human dentists have shared with me the fact that all species of animals maintain a state of disocclusion, or non-contact, of teeth, while at rest or in activities other than eating. (Try it - if you are not eating, are your teeth occluding right now? Ever see a horse sleeping with his lower lip hanging?) If the teeth are in contact while the body is moving, it would cause damage to the surfaces of the teeth. So, occlusion, or mastication of food, is only accomplished when the individual contracts its own masseters.
The horse has proven to me that balance is achieved by starting with the equilibration of the incisors first. Generally, a primary angle of adjustment is necessary there. If there is a great deal of change to be made, this should be done gradually, over time, as it is in humans. After all, it took a long time to develop; it should take a while to fix. I believe that no more than a farrier needs a grinder to balance a foot should a dentist need power equipment.
Spencer LaFlure Photo by David Ulloa © 2004 Valeo Films Inc.
Speaking of equipment, most equine dental tools are not ergonomically designed to fit in the horse's mouth, let alone help balance it. I've spent 3 years designing hand instruments that ergonomically fit the horse as well as the practitioner; this lends itself to bloodless horse dentistry and less discomfort after dentistry.
Another popular but questionable practice in equine dentistry today is the rolling or rounding of the first molars, called premolars, to produce what is called the "bit seat". Consider this: In the young horse, the incisors and 12 premolars are basically all that are present in the mouth until about age two, at which time the plates or sutures of the skull fuse together. I believe that by this, Nature dictates these teeth are of primary importance to balance the skull as it develops. When a bit seat is made in these young teeth (or at whatever age), it takes away most of the leading molar's surface-to-surface contact. Removal of this contact from this molar, a cornerstone of the mouth, creates a lateral (side to side) instability of the TMJ. I have seen this show up externally in a visual hollowing out of the horse's flanks. When a bit seat is not put into these molars (allowing for maximum surface-to-surface contact) I've found that there is a greater stability to the TMJ, and performance is enhanced.
What are we truly trying to accomplish with Natural Dentistry? Natural balance, in the mouth and the rest of the body. The jaw's ability to move forward, backward, left and right, up and down, is equal to the whole body's ability to do the same. The jaw's range of motion dictates the neck's range of motion, which in turn dictates muscle mass in the rest of the body. I wrote a thesis about 3 years ago (copies available) stating that whole horse restoration could be accomplished by whole mouth equilibration. The key starting point, as I have said before, is addressing the incisors first and proceeding from there to balancing the mouth in an anatomically correct way to fit each individual horse. For three years, I have been trying to disprove my own theory, and as of yet, there isn't one instance in which this theory has not held up. The outcome is this: the least modification of Nature has generally been in the best interests of both man and beast.
I believe that dentistry is an important piece in the equation of the total balance available to our horses today. Owners should be aware that there are many complementary fields of natural practitioners available to help your horses be the best they can be. You know, NASCAR has pit crews to help the car and driver achieve ultimate performance - you and your horse have a team, too. Natural Dentistry is a part of that team.