Problems of the Cheek Teeth (Molars and Premolars)
Sharp Enamel Points
The sharp enamel points develop because horses have hypsodont teeth, which means, that they are not covered by enamel all over the crown, leaving rings of enamel on the tooth surface surrounded by dentin and cement. As enamel is much harder than the dentin and cement it is worn down much slower allowing the sharp points to occur. These sharp enamel points occur on the outside of the upper molar arcades and the inside of the lower molar arcades as that the upper jaw is broader than the lower jaw. These points should be rasped by the vet or equine dentist to leave a smooth curve rather than the painful sharp point.
Long teeth
If a horse has lost a tooth, or a tooth has been extracted for some reason, the opposite tooth that was in occlusion has nothing to wear against. The result is a long tooth. This needs to be reduced regularly so that the horse doesn't develop any further dental problems.
Hooks and ramps
Horses teeth erupt constantly throughout the animal’s life and wear down against the opposing tooth. If the upper and lower tooth arcades are not aligned properly a part of the tooth will not be in occlusion and will not wear down leaving hooks and ramps to form. The hooks and ramps can prevent jaw movement and chewing, and it can also prevent the horse from lowering its head and collect itself properly (horses need to slide their lower jaw forwards to be able to bend the head down). The most common problem seen is hooks on the front edges of the upper cheek teeth and ramps on the back part of the lower cheek teeth. Irregularities like hooks and ramps should be corrected.
Wave Mouth
A wave mouth is when rather the flat grinding surface of cheek teeth has become uneven with peaks and troughs along the surface. This usually occurs secondary to other conditions such as missing teeth, hooks and ramps, old age or caps. The result can be problems with the normal movement of the jaw and thereby chewing the food properly and attempts should be made to rectify the abnormality.
Excessive Transverse Ridges
Horses cheek teeth all have transverse ridges which are fold of enamel that increase the surface area of the tooth to maximize the grinding action. Occasionally the molar rows aren't properly aligned causing sharp enamel points to develop and make a ridged appearance of the molars. This misalignment can be due to the anatomy of that particular horse’s mouth or secondary to other problems in the mouth. Any transverse ridges that appear ‘excessive’ should be reduced. It must be noted, however, that the size of the transverse ridges varies from horse to horse and if there are no obvious signs of dental problems and all transverse ridges are of the same size they should be left as they are.
Shear mouth
The angle of the cheek teeth should be 10-15 degrees, i.e. should slope slightly upwards from outside to inside on the lower arcade and vice versa for the upper arcade. When this angle becomes too steep it is known as shear mouth. This usually occurs secondary to other conditions where restriction in the movement of the jaw, abnormal chewing pattern and anatomical factors plays a role in the development of this wear pattern. Attempts should be made to rectify the abnormality.
Dental Caps
Dental caps occur when the permanent cheek tooth is erupting and the deciduous tooth forms a cap over it, protecting the tooth below, until it is forced out by the permanent tooth. Eruption of permanent teeth and shedding of decidious teeth can cause discomfort and pathological conditions such as chewing problems, anorexia, infection and an abnormal wear pattern. Removing the caps too early may damage the permanent tooth below, however, if a decidious tooth doesn't shed like it should, problems can occur. Dental caps can get stuck in the gums and can cause infection and also dislocate or damage the new permanent tooth trying to get in. Dislocation of the permanent tooth towards the palate can cause a pouch to form, gathering feed particles and bacteria into it and causing periodontal disease to follow. Tooth impaction can also occur where a decidious cap is retained. There will be pressure on the permanent tooth and root abscesses may occur. The fourth pre-molar, third cheek tooth, is most commonly affected as it is the last of the permanent teeth to erupt.
Young horses should be routinely checked to assess the shedding of the deciduous caps and where appropriate the caps can be removed to prevent further, more serious problems.
Fractured teeth
Fractured teeth can often cause pain and/or infection. The fractured tooth will usually have to be removed unless the horse is showing no outward sign of a dental problem, the tooth root is intact and the tooth itself is not loose. Once the tooth has been removed regular dental checks should be performed to prevent problems with the other teeth such as overgrowths. Radiographs are often required for an accurate diagnosis.
Supernumerary (too many teeth)
If too many teeth are present, caused by traumatical split of a tooth bud, or be congenital, there is very likely to be alignment problems and the development of hooks and ramps. The secondary problems can be dealt with by regular rasping, however, the extra tooth can be removed if it is causing a serious problem.
Tooth Root Abscesses
An abscess at the tooth root can occur secondarily to many problems within the mouth including most of those mentioned in previous sections. Affected horses will usually have bad breath, problems eating, etc and will have swelling of the jaw, sometimes with draining tracts. In cases where the upper jaw is affected (maxilla) there may be a nasal discharge as secondary infection of the maxillary sinus often occurs. Radiographs and in some cases a bone scan are required to accurately assess the problem. The affected tooth can be surgically removed or in some cases the abscess drained and curetted surgically. A small percentage of cases will respond to long-term antibiotic treatment alone.