Although periodontal disease is typically less common and severe in cats in comparison to dogs, this disease process is still the number one health problem diagnosed in feline patients. By just two years of age, 70% of cats have some form of periodontal disease. In the vast majority of cases, however, there are little to no outward clinical signs of the disease process. Therefore, therapy often comes very late in the disease course (if at all). Consequently, periodontal disease is also the most undertreated animal health problem.
Unchecked periodontal disease has numerous dire consequences both locally and systemically. These consequences are detailed briefly in this lecture and should be utilized to educate clients and improve compliance of therapeutic recommendations. Prior to the discussion of consequences, this article covers the pathogenesis of periodontal disease, clinical features, and diagnostic tests.
Following the discussion of periodontal disease, this lecture will present the current treatment recommendations for periodontal disease. This includes dental prophylaxis, basic periodontal surgery, extractions, and homecare. In addition, homecare and future directions will be covered.
Pathogenesis of Periodontal Disease
Stages of Periodontal Disease
Periodontal disease is described in two stages, gingivitis and periodontitis. Gingivitis is the initial, reversible stage of the disease process where the inflammation is confined to the gingiva. This inflammation may be reversed with a thorough dental prophylaxis and consistent homecare. Periodontitis is the later stage of the disease process and is defined as an inflammatory disease of the supporting structures of the tooth (periodontal ligament and alveolar bone) caused by these microorganisms. This inflammation results in the progressive tissue destruction, leading to gingival recession, periodontal pocket formation, or both. Small periodontal pockets can be reduced or eliminated by proper removal of plaque and calculus. However, periodontal bone loss is irreversible (without regenerative surgery.)
Periodontal disease is initiated when oral bacteria adhere to the teeth in a substance called plaque. Plaque is a biofilm, which is made up almost entirely of oral bacteria, contained in a matrix of salivary glycoproteins and extracellular polysaccharides. Calculus is essentially plaque which has become calcified by the minerals in saliva. Bacteria within a biofilm do not act like free living bacteria; and in fact, they are 1,000 to 1,500 times more resistant to antibiotics. The plaque on the visible surface of the teeth is known as supragingival plaque. Once it extends under the gingival margin and into the area known as the gingival sulcus it becomes known as subgingival plaque. Supragingival plaque and calculus has a slight affect the pathogenicity of the subgingival plaque in the early stages of periodontal disease, however, once a periodontal pocket forms, the effect is minimal. Therefore, control of supragingival plaque alone is ineffective in controlling the progression of periodontal disease.
Normal gingival tissues are coral pink in color (allowing for pigmentation), and have a thin, knife-like edge, with a smooth and regular texture. In addition, there should be no demonstrable plaque or calculus on the dentition.
The first clinical sign of gingivitis is erythema of the gingiva. This is followed by edema, gingival bleeding, and halitosis. Gingivitis is typically associated with calculus on the involved dentition but is primarily elicited by plaque and thus can be seen in the absence of calculus. Alternatively, widespread supragingival calculus may be present with little to no gingivitis. It is critical to remember that calculus itself is essentially non-pathogenic. Therefore, the degree of gingival inflammation (not the amount of calculus) should be used to judge the need for professional therapy. As gingivitis progresses to periodontitis, the oral inflammatory changes intensify.
The hallmark clinical feature of periodontitis is attachment loss, which has two different presentations. In some cases, the apical migration results in gingival recession while the sulcal depth remains the same. Consequently, tooth roots become exposed and the disease process is easily identified on conscious exam. In other cases, the gingiva remains at the same height while the attachment moves apically, thus creating a periodontal pocket. This form is typically diagnosed only under general anesthesia with a periodontal probe. It is important to note that both presentations of attachment loss can occur in the same patient, as well as the same tooth.
Severe Local Consequences
In addition to tooth loss, there are several local severe sequelae of severe periodontal disease seen in cats. There are others that are seen in dogs, but since they are rare in cats, they will not be discussed here.
The most common of these local consequences is an oronasal fistula (ONF). ONFs are typically seen in older felines. ONFs are created by the progression of periodontal disease up the palatal surface of the maxillary canines, however, any maxillary tooth is a candidate. This results in a communication between the oral and nasal cavities, creating an infection (sinusitis). Clinical signs include chronic nasal discharge, sneezing, and occasionally anorexia and halitosis. Definitive diagnosis of an oronasal fistula often requires general anesthesia. Appropriate treatment of an ONF requires extraction of the tooth and closure of the defect with a mucogingival flap.
Another potential local consequence of severe periodontal disease results from inflammation close to the orbit potentially leading to blindness. The proximity of the apices of the maxillary fourth premolars/first molars, place the delicate optic tissues in jeopardy. In addition, the apices of the maxillary canines lie in this area and can create similar issues, especially in brachycephalic breeds.
The other local consequence is described in recent studies which have linked chronic periodontal disease to oral cancer. The association in this case is likely due to the chronic inflammatory state that exists with periodontitis.
Severe Systemic Manifestations
Systemic ramifications of periodontal disease are also well documented. The inflammation of the gingiva and periodontal tissues which allows the body’s defenses to attack the invaders also allows these bacteria to gain access to the body. Recent animal studies suggest the possibility that these bacteria negatively affect the kidneys and liver, leading to decrease in function of these vital organs over time. Furthermore, it has also been suggested that these bacteria can become attached to previously damaged heart valves (e.g., valvular dysplasias) and cause endocarditis, which in turn can result in intermittent infections, and potentially thromboembolic disease.28 Other studies have linked oral bacteremias to cerebral and myocardial infarctions and other histological changes. Additional human studies have linked periodontal disease to an increased incidence of chronic respiratory disease (COPD) as well as pneumonia. There are many studies that strongly link periodontal disease to an increase in insulin resistance, resulting in poor control of diabetes mellitus as well as increased severity of diabetic complications (wound healing, microvascular disease). Additionally, it has been shown that diabetes is also a risk factor for periodontal disease. Periodontal disease and diabetes are currently viewed as having a bidirectional interrelationship where one worsens the other.
While some of these studies are not definitive, we know that periodontal disease is an infectious process and that affected patients must deal with these bacteria on a daily basis, which in turn can lead to a state of chronic disease. Therefore, we must learn to view periodontal disease as not just a dental problem that causes bad breath and tooth loss, but as an initiator of more severe systemic consequences. As one author states, “Periodontal disease is clearly an important and potentially life-threatening condition, often underestimated by health professionals and the general public”. Only by thinking in these terms can we fully appreciate the scope of the disease process and discuss the problem with clients so that they can appreciate the depth of the problems their pets face. This information will significantly increase client compliance with homecare and dental prophylaxis, as well as advanced dental procedures.
The basis of periodontal therapy is still bacterial plaque control. Therefore, treatment of periodontal disease is generally a two to four step procedure depending on the stage of the disease. These steps include a thorough dental prophylaxis, periodontal surgery, homecare, and extraction.
The cornerstone of periodontal therapy is a thorough dental prophylaxis. This must be performed under general anesthesia, and should include the following steps:
Step 1: Pre-Surgical Exam and Consultation
This is an often-neglected step of a professional dental prophylaxis. The veterinarian should perform a complete as possible physical and oral exam. The physical exam combined with pre-operative testing is important to screen for health issues and ensure anesthetic safety. The oral examination should identify obvious pathology as well as allow for a preliminary assessment of periodontal status. The veterinarian can then discuss the various disease processes and the available treatment options in person with the use of visual aids. This will greatly increase client understanding and compliance. Furthermore, based on the physical findings, the practitioner can create a more accurate estimate both of procedure time and financial costs to the client. This small investment of time will improve the experience of everyone involved (veterinarian, technician, receptionist, client, and patient).
Step 2: Supragingival Scaling
This step can be performed via mechanical or hand scaling. The mechanical scalers markedly decrease anesthetic time and include both sonic and ultrasonic types. The most common type of mechanical scaler in veterinary dentistry today is the ultrasonic. They are very efficient and have an additional benefit of creating an antibacterial effect in the coolant spray (cavitation). Sonic scalers run on compressed air and are slower than ultrasonic scalers and do not offer cavitation.
The area of maximum vibration for ultrasonic scalers is 1–2 mm from the tip. Do not use the very tip of the instrument as these are not effective for calculus removal and can potentially damage the tooth. The last 1–3 mm of the side of the instrument is placed on the tooth with a very light touch and kept in contact with tooth for up to 15 seconds. Once the instrument loses contact with the tooth, the instrument is no longer effective. The instrument should be kept in constant motion, running slowly over the tooth surface in overlapping wide sweeping motions to cover every mm2 of every tooth surface.
Supragingival hand scaling is performed with a scaler which is a triangular instrument with sharp cutting edges and a sharp tip. Typically, the blade is at a 90-degree angle to the shaft, which is called a universal scaler. Scalers are designed for supra-gingival use only. The scalers (as well as curettes which are described below) are held with a modified pen grasp. The instrument is gently held at the gnarled or rubberized end between the tips of the thumb and index finger. The middle finger is placed near the terminal end of the shaft and is used to feel for vibrations which signal residual calculus or diseased/rough tooth/root surface. Finally, the ring and pinkie fingers are rested on a stable surface.
Hand instruments must be employed with a gentle touch. The instrument is held parallel to the tooth surface and the blade placed at the gingival margin. Hand scalers are used in a pull stroke fashion, which avoids lacerating the gingiva by pulling away from the soft tissue. The scaler is activated numerous times in overlapping strokes until the tooth feels smooth.
Step 3: Subgingival Plaque and Calculus Scaling
This is the most important step of the prophylaxis, as supragingival plaque control is insufficient to treat periodontal disease. Unfortunately, this step is also the most difficult, resulting in the increased incidence of residual calculus increases with increasing pocket depth.
Subgingival scaling is classically performed by hand with a curette, however, advances in sonic and ultrasonic tips now allow their use under the gingival margin. A curette has 2 cutting edges with a blunted toe and bottom. This design allows for effective cleaning without cutting through the delicate periodontal attachment (as long as excess force is not applied). There are two types of curettes, universal and Gracey. Universal curettes have a 90-degree angle and can, therefore, be used throughout the mouth. Gracey curettes are area specific which means they are designed with different angles to provide superior adaptation to specific areas of the dentition. Curettes are labeled by numbers which are used as follows: the lower the number (i.e., 1–2) the smaller the angle of the blade and the more rostral in the mouth the instrument is used.
Manual subgingival scaling is a very technically demanding procedure and although it will be briefly described here, the practitioner is directed to continuing education programs (such as San Diego Vet Dental Training Center (www.vetdentaltraining.com) to hone their skills. Subgingival scaling is performed as follows. Place the face of the curette flat against the surface of the tooth. Next, insert the instrument gently to the base of the sulcus or pocket. Once there, the instrument is rotated so that the shaft is parallel to the long axis of the tooth. Upon rotation and proper angulation, the instrument is in proper position to engage the calculus as well as for root surface scaling and subgingival debridement. Finally, with the instrument in solid contact with the tooth, it is pulled from the pocket with a firm, short stroke. This technique is repeated with numerous overlapping strokes until the root feels smooth.
Traditional ultrasonic scalers should not be used subgingivally to avoid thermal damage to the gingiva and pulp. Thermal damage occurs if the water coolant cannot reach the tip of the instrument. Recently, sonic and ultrasonic scalers with specialized periodontal tips have been developed for subgingival use. Mechanical scalers are much easier to use appropriately than are curettes and thus are likely to provide a superior cleaning in the hands of novices. To accomplish subgingival scaling, these instruments are used in a similar fashion as supragingival scaling described above, however, more care should be taken not to damage the root surface.
Step 4: Polishing
Polishing smooths the surface of the teeth which retards plaque attachment. The polishing procedure is typically performed with a rubber prophy cup on a slow-speed hand-piece with a 90-degree angle. The hand-piece should be run at a slow speed, no greater than 3,000 RPM. It is important to be sure an adequate amount of polish is used at all times, as running the prophy cup dry is not only inefficient, it may also overheat the tooth. As with scaling, every mm2 of tooth surface should be polished. Slight pressure should be placed down onto the tooth to flare the edges of the prophy cup so as to polish the subgingival areas. One tooth may be polished for a maximum of five seconds at a time, to avoid overheating. The tooth can be further polished after a short break.
Step 5: Periodontal Probing, Oral Evaluation, and Dental Charting
This is a critically important step of a complete dental prophylaxis and is unfortunately often poorly performed or completely omitted. The entire oral cavity must be systematically evaluated using both visual and tactile senses.
The only accurate method for detecting and measuring periodontal pockets is with a periodontal probe, as pockets are not accurately diagnosed by radiographs. Periodontal probing is performed by gently inserting the probe into the pocket until it stops and then “walking” the instrument around the tooth. Depth measurements should be taken at six spots around every tooth. The normal sulcal depth of cats is 0–0.5 mm. All abnormal findings must be recorded on the dental chart. Using the modified Triadan system will also greatly increase efficiency of this step. It is important that dental charts be of sufficient size to allow for accurate placement of pathology. The minimum size for an acceptable dental chart is 1/3 of a page, however, veterinary dentists use full page charts.
Step 6: Dental Radiographs
Dental radiographs should be taken of every area of pathology noted on dental exam. Dental radiographs are a critical aid in the evaluation of dental pathology, however, they are not a substitute for the clinical exam.
Step 7: Treatment Planning
In this step, the practitioner uses all available information (visual, tactile, and radiographic) to determine appropriate therapy. It is important to consider overall patient health, the owner’s interest and willingness to perform homecare, and all necessary follow-up. After forming an appropriate dental treatment plan for the patient, an estimate should be created and the client contacted for consent.
Home care is a critical part of periodontal therapy. A recent study found that periodontal pockets are reinfected within 2 weeks of a prophylaxis if homecare is not performed. Therefore, the benefits of regular brushing and homecare must be discussed with each client following a prophylaxis.
There are two major divisions of dental homecare, active and passive methods. Both types can be effective if performed correctly, however, active home care is certainly the gold standard.
Active homecare consists primarily of tooth brushing. There are numerous veterinary brushes available, but a soft child’s toothbrush is also effective. There are also a number of veterinary toothpastes available. These products increase the palatability of the toothbrush, and many add a cleaning aid. Human tooth pastes are not recommended because they can cause gastric upset if swallowed. Antimicrobial preparations are also available and can be used instead of toothpaste in cases of established periodontal disease.
Proper brushing technique is a circular motion with the brush at a 45-degree angle to the gingival margin. Once a day is the ideal frequency, as this is required to stay ahead of plaque formation, but this is unrealistic for most owners. Three days a week is considered the minimum frequency for patients in good oral health. For patients with established periodontal disease, daily brushing is necessary.
Passive homecare is an alternative for minimizing periodontal disease and is achieved with special diets and treats. Since this method requires no effort by the owner, compliance is more likely. There are currently several available diets that decrease tartar and plaque build-up. Of the available diets, only one has been clinically proven to decrease gingivitis.
The downfall of all passive homecare products involves the fact that the patient is not likely to chew with all teeth equally and, therefore, areas will be missed. Passive homecare is most effective on the carnassial teeth; in contrast, active homecare is superior for the incisor and canine teeth. Therefore, a combination of active and passive homecare is best.
Any pockets with depths greater than 0.5 mm are pathologic and in need of therapy. Periodontal therapy involves removing the infection from the root (i.e., plaque, calculus, and granulation tissue), as well as smoothing the diseased root surface. These steps allow for gingival reattachment leading to a decrease in pocket depth.
In cats, pockets up to approximately 3–5 mm which are not associated with tooth mobility, furcation exposure, or other issues are best treated with closed root planing and subgingival curettage. This step is performed in a similar manner to subgingival scaling described above, with a combination of mechanical and hand scaling.
Pockets greater than 5 mm require advanced procedures for effective cleaning, owing to the fact that residual calculus is seen with regularity in pockets greater than 6 mm. In humans this is known as the 5 mm standard. In addition, periodontal surgery is also indicated for teeth with moderate bone loss, furcation level II and Ill, and inaccessible areas. Visualization is best accomplished via periodontal flap procedures, which should be offered if the clients are interested in salvaging the teeth. These are advanced procedures but can be learned by general practitioners.
The final modality for the therapy of periodontal disease is extraction. While extreme, it is the only true cure. Without a commitment to homecare or routine professional cleanings, advanced periodontal surgery should not be attempted. Furthermore, leaving periodontally diseased teeth in the mouth simply because “they are not loose” is not acceptable, as re-infection is imminent.