The Comprehensive Oral Health Assessment and Treatment (COHAT)

In veterinary dentistry, our patients need to be under general anesthesia for a comprehensive oral examination.  This examination involves:

• An overall assessment of the head for asymmetry, swellings, areas of sensitivity or pain, lymph node or salivary gland enlargement and malocclusion (abnormal bite)
• An assessment of all soft tissue structures of the oral cavity (tongue, palate, oral mucosa of the cheeks and pharynx, salivary glands, tonsils and laryngeal structures
• A tooth-by-tooth examination with a periodontal probe and dental explorer; the findings are recorded in detail on a dental chart.
• Whole mouth intraoral radiographs for assessment of the subgingival dental anatomy and staging of periodontal disease.

Anesthesia

While anesthesia-free veterinary dentistry (equivalent to human dentistry) would be nice, it simply is not possible in small animals, and is not recommended by the American Veterinary Dental College (AVDC). Therefore, it is imperative that veterinary dentists have excellent training in anesthetic techniques and that their operatories are equipped with the best equipment. Many of the patients presented to the veterinary dentist are geriatric individuals, often with concomitant medical problems. Therefore the decision to perform lengthy oral surgical procedures is not made lightly and anesthesia and pain management are as important as the oral surgery itself.

Pre-anesthetic considerations

All patients are given a general physical examination and medical records from the referring veterinarian  are reviewed. Blood is drawn for a complete blood count (CBC) and serum chemistry profile (this is an assessment of liver and kidney function). Dogs with a history of heart disease or a heart murmur may also get a cardiac ultrasound examination. The patients are usually fasted for 8-12 hours prior to general anesthesia.

Multimodal anesthesia

The use of multiple sedatives, analgesics and anesthetic agents that act synergistically, along with the use of regional nerve blocks, allows the clinician to use lower doses of these agents to obtain the desired level of anesthesia. This is very important, in that all anesthetics have potential deleterious side effects that are dose-related. Using smaller amounts of several drugs is much safer than using a higher dose of a single agent to obtain the same level of anesthesia. Equally important is the use of local anesthesia, which also permits the use of much lower levels of gas anesthesia throughout the procedure and allows the patient to recover from anesthesia pain-free.

Patient monitoring and support

Sophisticated monitoring equipment is required for proper monitoring of the patient during anesthesia. The patient's blood pressure, electrocardiogram (ECG), arterial oxygen saturation and carbon dioxide levels and the core body temperature are continuously monitored and recorded by the nurse anesthetist during the surgical procedure.  

Most surgical patients have a tendency to develop hypothermia during the surgical procedure, and this is even more likely in the smaller dogs and cats. To maintain body temperature, which is critical to proper heart function, a heated surgical table and a circulating hot air blanket are used for all dentistry procedures.

Anesthetic agents have some cardiac and respiratory depressant effects. To maintain proper tissue perfusion, the blood pressure is carefully monitored. Any fall in blood pressure is counteracted by lowering the anesthetic gas concentration, increasing the intravenous fluid rate and the administration of medications that improve peripheral blood pressure. Most dentistry patients are placed on a ventilator during the anesthetic period; this insures proper oxygenation of the tissues and prevents elevated concentrations of carbon dioxide in the blood. 

It is easy to see why proper anesthesia adds significantly to the expense of oral surgery in small animals. 

The oral examination

The oral examination usually begins in the conscious patient in the exam room. A slow, quiet
approach will often be well-tolerated by the patient, and an initial assessment of the head and oral cavity can be made. Oral masses, facial swellings, enlarged lymph nodes and fractured teeth can often be appreciated in the conscious patient. This allows the general practitioner to make a tentative diagnosis and leads him/her to a discussion of further treatment options that involve general anesthesia.

Soft tissue structures

With the patient under general anesthesia, a thorough examination of the oral cavity becomes possible. The oral mucosa, the epithelial lining of the entire oral cavity, is examined along with all aspects of the tongue, pharynx and larynx including the epiglottis, vocal folds, tonsils and salivary glands.

Toot-by-tooth examination and charting

Every tooth is examined with magnifying loops and the findings are recorded on a dental chart. Abnormalities of the crown include caries (cavities colonized by bacteria), fractures and developmental defects in the amount or quality of the enamel. The periodontium is the group of four tissues that anchor the tooth to the jaw and includes the gingiva, the periodontal ligament, the cementum and the alveolar bone forming the tooth socket. Periodontal disease is detected clinically by the loss of this attachment that results in deep periodontal pockets, gingival inflammation and recession, and mobility of the tooth. Intraoral radiographs are used to evaluate the amount of bone loss that is associated with periodontal disease. All of these findings are used to stage the periodontal disease and make a decision on the appropriate treatment. 

Early periodontal disease (Stage 1) consists of gingivitis, often associated with the accumulation of mineralized plaque, called calculus. This stage of periodontitis is reversed by professional scaling and polishing of the teeth, followed by good at-home oral hygiene by the owners. Malodorous breath (halitosis) is not normal. It is due to the sulfur-containing metabolites of the bacterial biofilm (plaque) on the teeth and calculus. Good oral hygiene in cats and dogs, just as in people, is required  to prevent bad breath.   Stage 2 periodontal disease is defined as loss of less than 25% of normal periodontal attachment. This stage is treated as for stage 1, recognizing that the attachment loss is not reversible. Stage 3 periodontal disease is loss of 25-50% of the normal attachment. Treatment at this stage involves periodontal surgical techniques that are aimed at regeneration of the periodontal tissues and attachment. This is specialized surgery involving the use of bone grafting techniques. Once there has been greater than 50% attachment loss (stage 4), extraction is  the only treatment option.

Intraooral radiography

X-rays of the teeth are absolutely necessary for the complete oral health assessment. Diagnostic quality dental xrays are only obtainable with imaging plates that are placed in the animal's mouth (intraoral). Since this would stimulate chewing in the awake patient, this procedure also requires general anesthesia. Since pathology below the gumline is frequently only evident in x-rays, it is highly recommended that a whole mouth radiographic examination be part of the COHAT. 

Treatment

Treatments of oral disease may be as simple as prophylactic scaling and polishing of the teeth, to as complex as root canal therapy or the surgical treatment of oral cancer. The veterinary dentist is trained in all dental sub-specialties: orthodontics, periodontics, restorative dentistry, maxillofacial surgery, and endodontics. The ultimate goal in veterinary dentistry is to provide the patient with a comfortable, disease-free mouth. Esthetics are of secondary importance in our pets, and are certainly much less important than in human dentistry. However, when possible, veterinary dentists still try to prolong the function of the teeth. 

This dog was presented for re-evaluation of the right mandibular canine tooth which had been fracture 3 years previously and treated endodontically (root canal therapy). Unfortunately, there were six new fractured teeth (files placed in the exposed pulp chambers) that required surgical extractions. Tooth fracture is commonly due to the use of excessively hard chews, such as NylaBones and deer antlers.

 
This dog had very little calculus or gingivitis (left) but survey intraoral radiographs identified a severely abscessed 2nd molar (right) which was surgically extracted.

 This dog also has minimal gingivitis. However, intraoral radiographs identified a large area of bone lysis, which turned out to be a cyst between the roots of the left maxillary 4th premolar. The cyst lining was carefully curretted and the gingiva was resutured in position.

 This cat has moderate gingival inflammation, plaque and calculus (left). The intraoral radiographs revealed marked tooth resorption of nearly all teeth (right mandibular cheek teeth shown in the xray on the right). Treatment was surgical extraction of all the affected teeth, which left only the 4 canine teeth in this case.

In conclusion, proper dental care requires general anesthesia for a comprehensive oral health assessment and treatment. Since much of the pathology is "below the gumline" and not evident on the oral exam of the awake patient, full mouth intraoral radiographs are routinely obtained.