Caries Lesion (Cavity)
A progressive destruction of the tooth structure secondary to bacterial microorganisms, on the tooth structure, that ferment carbohydrates (sugars) to acid that destroy the mineralized portions of the tooth while the bacterial enzymes destroy the connective tissues of the tooth. Treatment options include pit and fissure sealants, cavity restoration, or endodontics depending on the stage of the caries lesion.
Unerupted teeth (embedded or impacted) can lead to the formation of a dentigerous cyst. As the cyst expands within the bone, it causes destruction of the bone and adjacent teeth. This condition is preventable. If a permanent tooth has not erupted by 6 months of age or a tooth is missing with no history of extraction, it is important to complete intraoral dental radiographs to diagnose if an unerupted tooth is present or if the tooth is truly missing. Unerupted teeth should be extracted. If a dentigerous cyst has formed around an unerupted tooth then extraction of the unerupted tooth and surgical debridement of the cystic lining is indicated. The tissues are then submitted for histopathology to confirm a diagnosis.
Computed Tomography (CT)
Computed tomography uses x-rays to obtain images that are processed by a computer to allow geometric reconstruction (3D) of the region and digital slices of the anatomy for assessment. It provides superior detail when looking at the intricate and overlapping anatomy of the skull bones. In dentistry and oral surgery CT is often used for treatment planning for oral tumors, maxillary and mandibular fractures, intruded roots into the nasal cavity or mandibular canal, problems with the temporomandibular joints, difficulties or pain opening and closing the mouth, and assessment of some soft tissue diseases of the head.
Cone Bean Computed Tomography (CBCT)
Cone beam computed tomography is like traditional computed tomography. They both use x-rays to obtain images that are processed by a computer to produce an image, and both can generate a 3D reconstruction from the x-ray images. The main differences are the shape of the x-ray beams used and the time to complete an imaging series. A CBCT uses a cone shaped x-ray beam, and a traditional CT uses fan shaped x-ray beam. As a result, the CBCT captures a region of anatomy in a single beam and the CT requires multiple slices for the same region of anatomy. Due to its image quality, portability and decreased time and amount of radiation exposure, the CBCT is a popular imaging modality in dentistry.
Intraoral Dental Radiographs
Although CBCT is becoming a popular imaging modality, traditional intraoral dental radiographs (x-rays) are currently considered the gold standard for veterinary dentistry.
Dental disease in dogs and cats may not present with obvious clinical signs. Many ramifications of dental disease are below the gumline (gingiva) involving the tooth root and bone. Intraoral radiographs provide black and white images. These images allow assessment of the tooth roots and surrounding bone and are required to make a diagnosis.
Intraoral dental radiographs are invaluable in the assessment and identification of dental disease in dogs and cats. Published literature supports that intraoral radiographs will reveal significant information about the state of a pet’s oral health, allowing complete treatment.
Magnetic Resonance Imaging (MRI)
MRI uses a magnetic field and computer-generated radio waves to obtain images that are processed by a computer to allow geometric reconstruction (3D) of the region and digital slices of the anatomy for assessment. MRI does not use ionizing radiation (x-rays). MRI provides superior detail when evaluating diseases that cause soft tissue changes. It is utilized in dentistry and oral surgery for oral tumors of soft tissue nature, salivary disease, muscular disease, and atypical swellings of the head and neck.
Feline Juvenile Periodontitis
This is a pronounced generalized inflammation of the periodontal tissue (gingiva, cementum, alveolar bone, and periodontal ligament) in the young cat. It is typically diagnosed between 7-10 months of age. This juvenile form of periodontitis is suspected to be the result of an exaggerated tooth eruption inflammation in addition to a disruption of the equilibrium between the oral bacteria and the immune system. It is distinguished from other oral inflammatory disorders in that the generalized gingivitis has not radiated to the mucosa or caudal oral tissues as in stomatitis. Periodontal changes, including alveolar bone loss, gingival resorption, pocket formation, and/or root exposure can be seen. After 2 years of age some cats mature into a more normal state of equilibrium between the immune system and the oral bacteria. On the other hand, juvenile cats with this form of oral inflammation, can progress to severe periodontitis and tooth loss or even stomatitis.
Feline stomatitis is a painful oral inflammatory disease in cats and its management can be frustrating for clients and veterinarians. The pathogenesis of the disease is not fully understood, but it appears to be multifactorial with viral, infectious, and immune mediated mechanisms involved.
Stomatitis involves extension of inflammation beyond the gingiva and mucogingival junction to involve the mucosal lining of any structures within the oral cavity. Inflammation of the caudal oral cavity is a hallmark lesion of stomatitis.
It is important to differentiate stomatitis from other common conditions, such as periodontitis, epitheliotropic lymphoma, autoimmune conditions, and eosinophilic granulomas as examples. A biopsy may be recommended at the time of treatment.
Treatment recommendations may differ for each patient and client. Treatment options include partial-mouth extractions, full-mouth extractions, and or medical management. Intraoral dental radiographs, oral disease, patient discomfort, and response to previous treatment help determine the best plan for each cat.
Approximately 70% of cats have improvement following full-mouth extractions.
Unfortunately, in some cases the inflammation and clinical signs are not completely resolved, and medical management is necessary for these cats. Some cats require lifelong therapy.
There is ongoing research to help cats with stomatitis.
Feline Tooth Resorption
Feline tooth resorptive lesions are one of the most common problems in a cat’s mouth. The prevalence of the disease in cats has been reported in the literature as 20-75%. The cause of tooth resorption is not fully understood but may be multifactorial.
Tooth resorption can be found on the root, the junction between the root and the crown or just the crown. These lesions can sometimes be visible on a basic oral examination. However, a complete oral exam, intraoral dental radiographs under general anesthesia are required to identify the lesions and the extent of the resorption.
Tooth resorption progresses into the enamel and dentin of the tooth root and crown leading to the destruction of the tooth, inflammation of the gums, compromise of the root canal system, and in some cases, exposure of tooth nerves and severe pain.
The range of clinical signs can vary. If the lesions remain below the gingival attachment, they are often asymptomatic since the dentin tubules and pulp are not exposed to the oral environment. All other stages of disease can present with decreased appetite, weight loss, halitosis, ptyalism, pawing at the mouth and discomfort when eating.
Intraoral dental radiographs are utilized to assess the type of tooth resorption and determine the proper treatment. Therapy options for teeth with tooth resorption include extraction or subgingival crown amputation.
If the roots are resorbing and being replaced by bone (Type 2), subgingival crown amputation is often elected because they are less invasive compared to surgical extractions of ankylosed teeth. If the roots are not being replaced by bone (Type 1), surgical extraction is chosen.
Radiographically, Type 1 tooth resorption will have normal root opacity with a surrounding lamina lucida and usually a definable root canal. There may be associated periodontal or endodontic disease. With Type 2 tooth resorption, the teeth have undergone significant resorption and have opacity like the surrounding alveolar bone. There is loss of the lamina lucida and dentoalveolar ankylosis is present. There may be no discernable root structure present. Type 3 occurs when one root is Type 1 and one root is Type 2. It is essential that the surgeon use intraoral dental radiographs and understand Type 1, Type 2, and Type 3 lesions for treatment planning.
The disease is a progressive process. Therefore, follow up care to evaluate remaining teeth is also recommended.
After determination of type, tooth resorption can be staged. A staging scheme has been outlined by the American Veterinary Dental College.
Stage 1 (TR1): Mild dental hard tissue loss (cementum or cementum and enamel)
Stage 2 (TR2): Moderate dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not extend into the pulp cavity)
Stage 3 (TR3): Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does extend into the pulp cavity)
Stage 4 (TR4): Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does extend into the pulp cavity; most of the tooth has lost its integrity)
TR4a (crown = root), TR4b (crown > root), TR4c (crown < root).
Gingival Enlargement (Drug-induced Gingival Enlargement and Gingival Hyperplasia)
Pseudopockets are created when the gingiva enlarges and the marginal bone remains at the appropriate level. The gums enlarge and appear to grow over the teeth. These pseudopockets increase the risk of periodontal disease. Gingival hyperplasia has a familial tendency in breeds such as Boxers. Drug induced gingival enlargement can be a side effect of common veterinary medications such as cyclosporine and amlodipine. Treatment for gingival enlargement and gingival hyperplasia includes diligent oral hygiene paired with regular professional dental cleanings and surgical removal of the excess gingival tissue (gingivectomy). A representative sample of the gingival tissue is then submitted for histopathology to confirm the diagnosis and rule out other diseases of the gingiva. Depending on the underlying cause of the gingival enlargement/hyperplasia it is common to have reoccurrence and need repeated episodes of gingivectomy over time.
With normal occlusion, the mandibular incisors are positioned just behind and touching the maxillary incisors; the mandibular canines interdigitate, without touching, between the maxillary third incisors and canine teeth. The mandibular and maxillary premolars interdigitate, and the tips of the upper and lower second premolars are at the same horizontal level.
Malocclusions are deviations from the normal occlusion. Considered to be genetic or developmental in origin. Malocclusions are classified on whether they are a result of skeletal and/or tooth abnormalities.
- Class 1 malocclusion – normal relationship between the mandibles and the maxilla with malposition of one of more teeth.
- Class 2 malocclusion – the mandibles are equal in length but shorter than the maxilla.
- Class 3 malocclusion – the mandibles are equal in length but longer than the maxilla (may be considered normal in brachycephalic breeds).
- Class 4 malocclusion – one mandible or one side of the maxilla varies in length.
Malocclusion and Therapy
Malocclusions can result in trauma from abnormal tooth to tooth contact and tooth to soft tissue trauma. Treatment plans for malocclusions are varied and depend on the age of the patient, the teeth involved and whether there is any soft tissue trauma.
Ball therapy is an option for young pets and is most often recommended for correction of linguoversion (tipping inward) of the canines. The goal of ball therapy is to tip the teeth laterally (outward), alleviating any inappropriate occlusion.
The chosen ball or toy should be round or ovoid in shape. The texture should be firm. If the ball is too soft, it cannot create enough pressure to move the teeth due to compression of the ball when chewing. If the ball is too hard, it can create abrasive damage to the teeth. The surface of the ball should be smooth.
Size of the ball is critical. A ball that is too small will not apply appropriate pressures and could become a life threatening pharyngeal foreign body or gastric foreign body if swallowed. A ball that is too large may be rejected by the dog.
The ball should be wider than the distance between the cusp tips of the mandibular canine teeth, resulting in the ball resting at the coronal tips of the canine teeth. This maximizes the lateral (outward) tipping forces on the tooth. It should also rest slightly behind the canine teeth.
Example of Appropriate Ball Size
Care must also be taken to ensure that the dog does not hold the ball in the back of the mouth with the carnassial teeth. Dogs chew with the large carnassial teeth in the back of the mouth; they will preferentially chew or grab with those teeth, rather than the canine teeth at the front of the mouth.
The minimum requirement for success is to have the dog play with the ball or toy three times daily for at least fifteen minutes. To maximize the chances of success, longer and more frequent episodes are preferred if possible. All other toys in the house and yard should be removed, to encourage use of the properly sized and shaped ball or toy. Approximately ball play should occur about 15 minutes 3 times a day.
The earliest time that benefit may be seen is three weeks after initiation of treatment. In the paper by Dr. Verhaert, the time for treatment ranged from two to twelve weeks. Typically, younger dogs had shorter treatment times, with dogs 5 months of age having shortest times, and dogs seven to nine months of age requiring the longest times to achieve correction. If no progress is seen at the three-week reassessment, other treatment options should be reconsidered.
ref: Verhaert, L. A Removable Orthodontic Device for the Treatment of Lingually Displaced Mandibular Canine Teeth in Young Dogs. J Vet Dent 16(2); 69-75, 1999.
In some cases where a tooth is causing trauma to the soft tissue in the oral cavity and/or creating holes in the hard palate [e.g. base narrow (linguoversed) mandibular canine teeth)] the offending tooth can be reduced in height. However, since the pulp cavity will be exposed when crown reduction is performed, a partial coronal pulpectomy and direct pulp capping (vital pulpotomy) must be done with the procedure to protect the pulpal tissues.
The goal of this therapy is to mitigate or eliminate a developing malocclusion in a young animal and often involves extraction of a deciduous tooth that is contacting another tooth or the soft tissues and interfering with occlusion and causing pain.
Orthodontic tooth movement may be chosen to provide a pain free and functional occlusion for the patient. Common treatment options in this category include incline planes, crown extension and power chains with brackets (like human braces).
A committed client is necessary to maintain oral hygiene and to present the patient for timely reevaluations to increase success rates and reduce the risk of treatment complications. The patient must be compliant with the appliance and the required daily cleanings, as well as being medically stable for multiple anesthetic procedures.
Some potential complications and sequelae to orthodontic tooth movement are resorption of treated teeth, fracture or loss of the appliance or associated teeth, delayed movement of treated teeth, and re-adjustment of the appliance during treatment.
Orthodontic movement of teeth is not intended for all patients, all clients, and all cases. It should not be attempted unless the veterinarian is appropriately trained in orthodontic tooth movement, related complications, and related sequelae.
It should not be done to mislead, defraud, or to propagate questionable genetic traits in the animal.
Kitten in orthodontic treatment.
Maxillary and Mandibular Fracture Repairs
Maxillary and mandibular fractures often occur secondary to trauma and/or severe dental disease (e.g. periodontal disease, endodontic disease). A tape muzzle may be used to temporarily stabilize the fractures while other associated life-threatening trauma induced conditions are treated. Once your pet is stable for general anesthesia, oral fractures can be repaired.
Severe bone loss from periodontal disease and/or endodontic disease in the mandible of the dog, particularly small breed dogs, weakens the bone and forces that would not normally lead to fracture can cause the mandible to easily break.
Computed tomography (CT) imaging will be recommended prior to surgical intervention for fractures of traumatic origin. It is common to have additional maxillofacial fractures and injury to the temporomandibular joints not found on routine exam or with radiology. Advanced imaging allows for a more thorough assessment of the patients injuries and accurate surgical planning.
Mandibular and maxillary fractures are repaired with preservation of teeth and maintenance of normal occlusion as a goal. Techniques that avoid damaging root structures, neurovascular bundles, and adjacent teeth are used. Infected and abscessed teeth in and near the fracture site, can inhibit bone healing and need treatment or extraction.
Examples on surgical techniques for stabilization include interfragmentary and interdental wire techniques. Interdental wires are placed strategically to stabilize the fracture and are reinforced with composite to give added strength to the surgical construct. Interfragmentary wires are placed within the bone on either side of the fracture for stabilization.
Placing the teeth in occlusion via the use of non-invasive intraoral fracture techniques allows rapid return to function and maintenance of an appropriate occlusion. A recheck schedule is then designed based on the extent of the injuries and the patient’s age.
Oronasal Fistula/Oroantral Fistula
An oronasal fistula (ONF) or oroantral fistula (OAF) is a communication between the oral and nasal cavity. There may be an obvious defect in the upper jaw secondary to trauma, extracted tooth, or lost tooth. The size of a defect on the surface is not typically a good indicator of the underlying defect in the bone. We know that the bone defect must be at least as large as the tooth that originally or currently occupies the space. There may also be inapparent hidden ONF associated with a diseased tooth. The communication can result in chronic inflammation of the nasal cavity (rhinitis) and nasal discharge (e.g. blood, mucous, clear fluid). Regardless of the cause the defect requires surgical repair.
Root Canal Treatment
Total pulpectomy (root canal treatment) is used to treat teeth with complicated crown or crown-root fractures. Often root canal treatment is chosen for strategic teeth (mandibular and maxillary canine teeth, maxillary 4th premolars, mandibular 1st molars) and aesthetic teeth (incisors). However, root canal treatment may be selected for any tooth depending on the purpose of the patient and the client’s desires. Root canal treatment includes mechanical and chemical removal of pulp, bacteria, dentin, and toxins while shaping the canal for a 3-dimensional obturation. The canal is obturated with endodontic sealants and core materials. Finally, a restoration is placed to complete the procedure. A crown may be placed to help protect the tooth and restoration. Reassessment 12-18 months after treatment is recommended and annually thereafter.
Surgical Root Canal Treatment
Surgical endodontics involves removing the apical portion of the tooth and adjacent infection. The objective is to remove damaged apical and periapical tissue and seal the endodontic canal with a retrograde filling. The commonly treated teeth are the canine and carnassial teeth in the dog. This treatment is often selected to correct a standard root canal treatment that has failed. Reassessment 6-12 months after treatment is recommended and annually thereafter.
Temporomandibular Joint (TMJ)
The temporomandibular joint (TMJ) is comprised of a transverse condylar process of the mandible that articulates with the mandibular fossa of the temporal bone. There is a dorsal and ventral compartment separated by fibrocartilaginous tissue. The retroarticular process and the articular eminence are bony boundaries that strengthen the articulation of the joint. The lateral ligament tightens as the jaw opens. The TMJ moves in flexion, extension, and translation (rostral and lateral movement). Translation is decreased in strict carnivores such as the cat. Canines and felines have a mandibular symphysis that joins and allows independent movement of the two mandibles. Computed tomography is the best imaging modality to diagnose an injury/abnormality of the TMJ (fracture, luxation, dysplasia).
A fracture of the temporomandibular joint has special issues to consider. Ankylosis (fusing of the bone) or pseudankylosis (scar tissue stopping joint movement) can occur which can inhibit the ability to open the mouth. This can occur up to 18 months after the time of injury. If this occurs, a condylectomy (surgery to remove the joint) may be required. A TMJ fracture is often repaired with a tape muzzle or interdental bonding, as indicated, followed by a rapid return to function and rehabilitation to minimize the risks of TMJ ankylosis.
TMJ luxation can occur with or without associated maxillofacial fractures. Often, but not always, the mandibles will deviate away from the contralateral (opposite) side involving the TMJ luxation. The mouth will often be slightly open but cannot be closed completely. Treatment requires anesthesia, reducing the luxation, followed by a tape/nylon muzzle or interdental bonding for approximately 2 weeks. The longer the joint remains luxated the harder it is to reduce successfully, so it is important to reduce the luxation as soon as possible.
Patients that have sustained trauma to the TMJ are at risk of ankylosis (fusing of the bone) or pseudankylosis (scar tissue stopping joint movement). These complications can occur up to 18 months after the initial trauma and may hinder the ability for the patient to open their mouth appropriately.
Patients affected with TMJ Dysplasia are at increased risk of coronoid displacement/entrapment (open mouth jaw locking). The dorsal aspect of the coronoid (bony prominence at the back of the lower jaw) is trapped ventral or lateral to the side of the zygomatic arch (cheek bone) on the contralateral (opposite) side of the dysplastic TMJ joint. These classically present with the mouth locked wide open. Yawning may proceed the open mouth jaw locking. Additionally, patients may have a history of rubbing or pawing at the face. Treatment includes anesthesia, partial zygomatic arch resection and/or dorsal coronoidectomy.