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Sylvia Johanna Read

Neuromuscular Dentistry for the Equine

Restoring balance to restore the horse!

I often start my introduction to the concept of Neuromuscular Dentistry for the Equine by saying that “If I only look at teeth, the only thing I see is teeth”.

This usually does not come as a surprise to clients who have already embraced a more holistic approach in the care for their equines including tack, toes, training and turnout.Teeth are essential for mastication, but are also part of a much bigger picture that embraces vital affecting health, well-being and performance throughout the entire body. The relationship of dental structures to body mechanics and neural connections has well been studied in research on humans (1, 2, 3). It is now receiving growing attention in the equine field as well, as integrated care concepts replace traditional standards.

Neuromuscular Dentistry promotes the harmonious relationship between the occlusal surfaces of incisors, molars and the temporo-mandibular joint (TMJ) and provides stability, balance and guidance in all three. The paradigm is to restore balance in order to restore the horse.

Observations/Reports After Neuromuscular Dentistry:

These include improved posture and muscle development, increased proprioception through optimal balance, corrected postural changes, refined body movements, increased resistance to injury, a more calm and relaxed behaviour, enhanced mastication and digestion, less temporo-mandibular joint (TMJ) sensitivity, a happier, healthier companion and increased tooth life.

The focus of Neuromuscular Dentistry lies in providing optimal occlusal relationship and alignment of the incisor and molars that are anatomically correct for the individual horse. The focus on the individual is an important factor to realise as each and every horse is different. A correct and balanced bite alignment further promotes the decompression of the TMJ, as well as the cranial nerves and the masticatory muscles.

Temporo-Mandibular Join (TMJ)

“ A powerful convergence point and more than just a bite:”

Research has shown that balance and posture are closely linked to TMJ function, because of direct innervation from the trigeminal nerve afferents (sensory nerves) of the TMJ to the vestibular nuclei of the brain, where all postural information is processed ( (4, 5, 6). One of the important reasons for this connection is the need for postural adjustment during mastication, since the jaw movement of chewing changes the instantaneous centre of mass of the head and neck, triggering coordinated neck position adjustment (7, 8).

Anatomy: The TMJ (Fig 1) is the articulation between the temporal bone of the skull and the mandible and has two types of motion, a hinge motion (ginglymoid), and a sliding motion (arthrodial).  

The two main functions of this joint are mastication and contributor of postural information (proprioception).  Because of this dual function the TMJ is highly innervated.

The highest concentration of mechanoreceptors (sensory nerves that report shape change) cells is found in the periphery of the intra-articular disc and its attachments via the lateral ligaments to the joint capsule (9, 10). The articular disc, much like the meniscus of the knee, has two synovial cavities, one on the top and one on the bottom, which enables the mandibular condyle to glide smoothly over the articular tubercle.

This proprioceptive (positioning signalling) array is similar to that found in the soles of the feet and upper cervical muscles, suggesting that information about the position of the articular disc and the forces acting upon its capsular suspension system are used by the central postural system to perform balance and righting tasks (11).  It tells the horse where it is in space, or what its posture is, where the legs are placed over that jump, or on that rocky uneven trail.

The articular surface of the equine TMJ is functionally concentric with the Curve of Spee, a curve that connects the occlusal surfaces of mandibular cheek teeth and is tangent to the condyle of the mandible (Fig. 2).

In human dentistry, it is emphasised that a levelling of the Curve of Spee by means of orthodontic procedures should be avoided since this manoeuvre causes destructive lever actions in the temporo-mandibular joints (12).

Any change made to the natural alignment of the individual horse ´s teeth through human intervention will result in neurologic adaption, cartilage and bone remodelling in the TMJ and concurrent functional changes in the entire stomatognathic system (13,14), a neurological system that governs balance and equilibrium. This system consists of the parts of the head (teeth, jaw, skull, hyoid apparatus), the neck and the upper thorax/shoulders.

Problems affecting the head or jaw may therefore directly affect the shoulders and posture, and vice versa.

The TMJ, hyoid apparatus and shoulders are intricately connected not only by this system, but also by muscles, bones, tendons, ligaments and fascia.

Neuromuscular Dentistry allows for the neuromuscular feedback pathways to remain effectively functional.

In this way, an optimal posture of the head and neck can be achieved that directly influences the linear connection of the three main junctions that affect the horses whole body: poll-atlas junction, neck-shoulder-withers, and hind-end junction.

First things first: “Incisors”

With Neuromuscular Dentistry, incisors are the beginning point and the most important part of a horse ´s dentition. They support and guide the TMJ, which in turn influences how your horse will move and stand (proprioception). When the incisors allow for complete anterior/posterior, as well as lateral motion, the horse ´s body will also have full range of motion.

During the initial evaluation, I look at the incisor length and angle which in turn influences the biomechanics of the TMJ. 

With Neuromuscular Dentistry, incisors are the beginning point and the most important part of a horse ´s dentition. They support and guide the TMJ, which in turn influences how your horse will move and stand (proprioception). When the incisors allow for complete anterior/posterior, as well as lateral motion, the horse's body will also have full range of motion.

During the initial evaluation, I look at the incisor length and angle which in turn influences the biomechanics of the TMJ.

Are they aligned top to bottom? Is there a wedge causing the mandible to be higher and more compressed on one side than the other? Is there an overjet, possibly obstructing the mandible to move freely from side to side as well as restricting anterior/posterior

Detailed understanding and knowledge of dental anatomy are critical in understanding how teeth function and how pathology develops. Occasionally incisor pathology can only be adjusted in increments while the horse adjusts to the new alignment and guidance to the TMJ.

The neurological connection between jaw and spinal mechanics:

When teeth occlude (when the top and bottom teeth come together), periodontal afferents (pressure receptors in the bone supporting the teeth) feed information to the main sensory spinal tract and mesencephalic nucleus of the trigeminal nerve. Communication then occurs in the fore/mid-brain, brainstem and with the spinal nerves. So in essence, the ways the jaws come together directly influences the spinal stem and thereby posture and muscular alignment (15).

Balance and posture are intimately linked to TMJ function.

A study has determined that dental occlusion/TMJ status exerted an influence on (I) synchronisation of head and jaw muscles with the muscles from other body sites for proper body posture; (II) body stability such as body equilibrium (balance), centre of gravity fluctuation and gaze stability; and (III) physical performance along with physical fitness (16).

Anatomically correct incisor length and angle together with optimal occlusal relationship and alignment of the molars creates balance, guidance and stability to the TMJ. Any imbalance in a horse ´s dentition will affect the neurological and proprioceptive function of the TMJ.

Cranial nerves: the “trigeminal nerve”

One of the most important cranial nerves to remember is CN V or the trigeminal nerve (the largest of the 12 paired cranial nerves). It is a complex nerve that has three branches that travel out into the head of the horse. This nerve is responsible both for sensation to the head and face, and also provides motor function to the chewing muscles. The information sent to the brain covers everything from temperature, pressure, proprioception and pain. The three branches are the ophthalmic (VI), maxillary (V2) and mandibular (V3) portions. The important factor to take into account, as a Neuromuscular Dentist, is that the extension, both of the maxillary and the mandibular nerve, provide sensory innervation to the upper/lower cheek teeth as well as to the upper/lower incisors. Pain stemming from dysfunction in this nerve can cause behavioural issues such as head shaking, head tossing, chewing on the bit, difficulty bridling/haltering, sensitivity to the head/poll area, tensed muscles of the jaw or a number of other undesirable actions.

Neuromuscular Dentistry: “The practical part” - No two horses are ever the same!

The consultation begins with 1) observation. Are there any asymmetries on the skull/face? I check the ears, facial crest, eyes and nose. Any reaction to touching ears, the head, face in general? Is the mandible able to move freely and equally from side to side?

I then move on to 2) palpation. Gentle palpation of the TMJ joint space can indicate asymmetry and/or indicate pain. During palpation, I feel the masticatory muscles and check for hyoid sensitivity.

Next follows a 3) whole body evaluation, including range of motion (ROM) of poll/atlas and lateral cervical flexion. I check for forelimb and/or  shoulder restrictions, top line condition, and palpate the hind end, including the sacroiliac joint, lumbo-sacral junction, hip, hamstrings and hocks.

This initial evaluation takes about 20 minutes and my clients (horses and humans alike) are overwhelmingly in support of taking this extra time to look at the whole horse, noting any asymmetries and collecting information about past or present, chronic or acute issues regarding body and behaviour. A wealth of information can be gained about the mouth by assessment of body conformation, posture, and the ability to move freely during turn out or exercise.

After a thorough fact-finding mission - all of which goes into a database to be able to correlate any findings - the neuromuscular dental work begins, starting with the incisor evaluation, balancing them according to what is anatomically correct for the individual horse. Once guidance, balance and stability to the TMJ is restored I move onto to apply the neuromuscular dentistry paradigm to work on the alignment and occlusion of the cheek teeth (molars). A typical visit lasts about 60-75mins/horse.

My aim is to maximise your horse ´s potential, health, and overall well-being:

At the core of Neuromuscular Dentistry is finding answers as to why the horse ´s body is out of balance. Simply looking at teeth, disregarding the need for a “whole mouth balance” with its vital neural and biomechanical connections highlighted in this article, creates compensatory patterns and inappropriate posture.

An out-of-balance TMJ is the cause for many dysfunctions in the body. Such signs include mystery lameness, tendon and ligament injuries, tension in poll and around the ears, short striding or inability to extend the forelimb, lack of proprioception, including tripping and balance issues, lack of hind end engagement, and the list goes on….

A recent case study from South Africa, demonstrates the effects Neuromuscular Dentistry can have on your horse when balance is restored in the mouth and, subsequently, in the body:

Sylvia Read is a Certified Natural Balance Dentist trained by Spencer LaFlure, founder of the Original Centre for Natural Balance Dentistry™, US.

Further certifications and qualifications include: Certified Masterson Method Practitioner MMCP, Fascia, Anatomy and Biomechanics Assessment courses (2016-1018) by Tuulia Luomala, Dr. Vibeke Sodring Elbrond, MVDr. Ivana Ruddock-Lange and Sharon May-Davis, Primary Equine Ergonomist course with Saddlefit4Life Academy (2017-2018), Equine Nutrition by Dr. Jo-Anne Murray of the Royal (Dick) School of Veterinary Studies, University of Edinburgh (2014).

Sylvia Read, email: [email protected]

https://www.equi-librio.pt

Center for Neuromuscular Horse Dentistry:

http://www.neuromuscularhorsedentistry.com

Acknowledgments: The author wishes to thank Diane Howard, PhD, for her excellent assistance and guidance with the preparation of this article.

References

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