Article reprinted with the permission of DVM360, MARCH 2016, DVM360 Magazine is a copyrighted publication of Advanstar. Communications inc. All rights reserved.
Mar 14, 2016
By Jan Bellows, DVM, DAVDC, DABVP, FAVD
Our alphabet of 26 letters forms the foundation for billions of words. I’ve narrowed the list down to a mere
26 related to dental care in pets. I hope you enjoy this series of articles starting with A for dental anaesthesia and ending with Z for dental zebras (I’m still searching for a good Y dental concept if you have one please email me at firstname.lastname@example.org). Each letter holds major importance in our quest to do the best for our veterinary patients.
A is for Anaesthesia
Most people recline in the dental chair, open their mouths and are OK with a suction tube placed under their tongues, probes placed into their sulci and radiograph sensors placed next to their teeth. But dogs and cats will not tolerate this without a fight — and who wants to fight? General anaesthesia is needed to thoroughly clean, polish and examine the teeth and oral cavities in our patients (Fig 1).
Figure 1. A peek inside All Pets Dental, Dr. Bellow’s veterinary practice in Weston, Florida. (Photos courtesy of Dr. Jan Bellows)
Unfortunately many of our clients are so worried about anaesthetising their dogs and cats that proper care is declined. How can you allay your clients’ fears? Share with them the efforts you take to make anaesthesia as safe as possible by choosing the right patient for anaesthesia through preoperative testing, tailoring the anaesthetic protocol, and monitoring the effects of anaesthesia before and after the procedure.
Monitoring. Close patient monitoring is paramount during and after anaesthesia. (All photos courtesy of Dr. Jan Bellows)
The American College of Veterinary Anesthesiologists (ACVA) recommends monitoring for:
1. Circulation — Ensure that blood flow to tissues is adequate; measured via blood pressure.
2. Oxygenation — Ensure adequate oxygen concentration in the patient’s arterial blood; measured via pulse oximetry.
3. Ventilation — Ensure that the patient’s ventilation is adequately maintained; measured via capnography (Fig 2A).
Figure 2A. An in-line capnograph.
The ACVA recommends having a trained veterinary technician at the patient’s side. The technician can respond to feedback from the electronic monitoring system, use his or her hands-on clinical expertise to manage the patient’s proper anaesthetic depth, and maintain an anaesthetic record of significant events and trends in monitored parameters. In our procedures, the technician relays information to the veterinarian, who is appraised of the patient’s condition at least every five minutes throughout the procedure (Figure 2B).
How to monitor. Monitoring is accomplished through subjective methods (e.g. clinical appearance) and objective methods (e.g. electronic systems). During anaesthesia, the patient should have minimal jaw tone and no palpebral reflex. The femoral pulse should be palpable, and the perfusion time should be two seconds or less. Breathing during balanced anaesthesia should be even and regular.
Figure 2B. A dental technician monitoring, relaying and recording anaesthesia monitor findings.
Electronic monitors may detect anaesthetic complications before being recognised by a trained clinician. In these situations, seconds count. Often, the advanced warning systems can head off problems before they become critical or do long-term damage. Electronic monitoring systems help to provide positive patient outcomes and reduce stress during the procedure.
Although many veterinary hospitals have accumulated a variety of monitoring devices, often single-parameter monitors, it would be wise to migrate to a 5-in-1 multiparameter monitor for all anaesthetic procedures (Fig 2C). An ideal monitor includes noninvasive blood pressure measurement, capnography, pulse oximetry, electrocardiography and temperature. The advantages of a multiparameter monitor over individual devices include:
Figure 2C. A cat monitored during anaesthesia with 5-in-1 parameter electric and apnea monitors
1. More efficient for patient set-up and alarm management
2. Consistent operating menu
3. Ability to store, print and download data for all parameters
4. Economy of scale — less expensive than acquiring individual devices
5. Single point of contact for service, maintenance and troubleshooting
Be aware that choosing a monitor that has been designed specifically for use on animals can make a significant difference in performance and accuracy.
Local anaesthesia. Every oral procedure performed that may be painful should be accompanied by local anaesthesia. The two most commonly performed local anaesthetic blocks are the maxillary (Fig 2D) and mandibular (Fig 2E), which can be performed either intraorally or extraorally.
Figure 2D. Site for a maxillary nerve block. (Illustrations by Sathyanarayana)
Figure 2E. Site for a mandibular nerve block.
Honourable mentions for A-analgesia, apical attached gingiva.
B and C are for the Basic Concepts of operative dentistry
Creating a dental treatment plan can be confusing and frustrating. As with other veterinary disciplines, dental diagnosis and care entails approximately one-third understanding of anatomy, physiology and dental principles; one-third recognition of disease; and one-third access to proper equipment and expertise to perform needed care.
Most dental problems can be treated by one of the eight options below:
1. Do nothing with the observed pathology other than future follow up. No immediate treatment is needed where there is a functional abnormality (i.e. even though the dentition is not normal, the animal is not experiencing adverse effects). One example of a functional abnormality is an enamel fracture that does not penetrate the dentin sufficiently to affect the pulp and where radiographs do not show pathology. Other cases where no treatment is the best course include functional malocclusion (Figure 3) and when the root of a tooth shows external resorption that does not extend into the oral cavity (Fig 4).
Figure 3. This left mandibular canine is malpositioned caudal to the maxillary canine but is not expected to cause a problem.
Figure 4. External resorption lesion (arrow) affecting the mesial root left mandibular fourth premolar. No intervention is necessary at this time.
2. Teeth cleaning, irrigation, polishing and application of professional plaque barrier gel or dental sealant. These measures are indicated in cases of stage 1 gingivitis (inflamed gingiva without evidence of support loss) and stage 2 nonpocket periodontal disease (less than 25 percent support loss) as evidenced by gingival recession.
3. Periodontal treatment
• Local antimicrobial administration of clindamycin hydrochloride or doxycycline hyclate can be used to treat stage 1 bleeding on probing points (Figs 5A and 5B) and stage 2 (less than 25 percent of support loss) and stage 3 (25 to 50 percent support loss) periodontal disease when cleaned periodontal pockets (in contrast to gingival recession) are present. The pet owners can provide additional home care to control periodontal disease progression. The periodontal gels Clindoral (TriLogic Pharma) and Doxirobe (Zoetis) are not available in South Africa, human equivalents will need to be used. Ed.
Figure 5A. Bleeding is evident on probing.
Figure 5B. Application of clindamycin hydrochloride
• Surgery can save teeth if the tooth and patient are appropriate. Operculectomy (removal of the gingiva over a partially erupted tooth crown) is indicated in a young dog or cat (less than 8 months old) whose tooth is expected to fully erupt once the obstructing gingiva is excised (Figs 6A-6C). Open flap exposure for cleaning and débridement is used to expose a tooth root in selective cases where the periodontal pocket extends greater than 5 mm and the client is committed to save the pet’s teeth despite a guarded prognosis.
Figure 6A. A missing mandibular first premolar evident on oral examination.
Figure 6B. The premolar is present on an intraoral radiograph.
Figure 6C. After an operculectomy, the premolar erupts normally
4. Endodontic care
• Vital pulp therapy can be performed when a complicated tooth fracture is acute (no longer than two days). The treatment usually results in a vital tooth with a good prognosis. If the fractured tooth with pulp exposure has been present for more than two days, extraction or conventional root canal therapy should be performed with a more predictable outcome (Figs 7A-7C).
Figure 7A. A complicated left maxillary canine fracture in a cat.
Figure 7B. Application of mineral trioxide aggregate (MTA) on vital pulp.
Figure 7C. The restored vital canine
• Root canal therapy is the treatment of choice for end-stage pulp disease secondary to fracture, chronic pulpitis or caries. Ideal therapy depends on the animal’s age, the age of pulp exposure, the tooth’s condition and periapical health (Figures 8A and 8B).
5. Crown reduction with gingival closure. This intervention can be used to treat Type 2 tooth resorption with evidence of root replacement (Figs 9A-9D). Crown reduction and restoration are indicated for cases of maloccluded teeth interfering with the opposing gingiva.
Figure 8A. A complicated crown fracture more than two days old.
Figure 8B. Root canal therapy was performed to save the tooth.
Figure 9A. Tooth resorption in a cat’s mandibular third premolar.
6. Orthodontic intervention. Orthodontic buttons and elastics can be used to reposition teeth into functional occlusion and for maxillary or mandibular fracture stabilization. Inclined planes made from acrylic or metal can move mesioverted mandibular canines into functional positions (Figs 10A-10C).
Figure 9B. A radiograph of the same tooth consistent with type 2 root replacement resorption.
Figure 9C. Gingival exposure and crown amputation.
Figure 9D. After gingival closure.
Figure 10A. A mesioverted maxillary canine in a Shetland sheepdog.
Figure 10B. Orthodontic buttons and elastics were used to pull the canine caudally.
Figure 10C. A functional occlusion five months later.
7. Oral surgery. Surgery is the treatment of choice to care for many oral masses, both benign and malignant. When planning oral surgery, the goal is to achieve a 1-cm tumor-free margin for benign masses and a 2-cm or greater margin for malignant oral tumors.
• Tooth extraction is indicated when stage 4 periodontal disease is present (the tooth has more than 50 percent support loss based on probing depths, greater than stage 2 mobility or gingival recession that has progressed past the mucogingival line).
• Extraction is the best therapy when the tooth has between 25 and 50 percent support loss and the owner or the patient will not allow appropriate allow home care.
• Some fractured teeth are best extracted, especially those that have pulp exposure and stage 3 or 4 periodontal disease or marked internal resorption.
• Extraction is indicated when root canal therapy is not a viable option due to the owner’s wishes or the practice’s capability (and lack of a referral option).
• Feline teeth should be extracted via flap exposure when, in addition to the resorption, there is visible periodontal ligament and normal opacity on intraoral radiographs (Types 1 and 3).
• Many cats affected by oropharyngeal inflammation that do not respond to home plaque control care benefit from the extraction of the teeth distal to the canines; those that still do not respond should have all the teeth extracted.
• Extra (supernumerary) teeth that cause crowding, predisposing the normal teeth to periodontal disease, should be extracted.
• Persistent primary (deciduous) teeth should be removed at the time of diagnosis to prevent the potentially harmful location of the adult teeth
• Extraction is the treatment of choice for advanced caries.
Honourable mentions for B & C— bacteria, bupivacaine hydrochloride, bur, calculus, caries.