A full periodontal examination in dogs and cats can only be performed under general anaesthesia. The most widely used diagnostic tool utilized for this purpose is the periodontal probe. Numerous different types of probes are marketed. The author prefers the Marquis probe with colour markings at 3, 6, 9 and 12 mm and the Michigan-O probe with Williams markings at 1, 2, 3, 5, 7, 8, 9, 10 mm, which are easy to read whilst taking measurements and are thin enough to be used in both dogs and cats (figure 5).
|
Fig. 5 : Michigan-O periodontal probe with Williams markings (left) and Marquis probe (right). © Gracis
|
Like most dental instruments, the probe should be held using a modified pen grasp. The index and middle fingers are placed opposite to the thumb, with the pad of the middle finger against the shank of the instrument (figure 6). The ring and the little fingers are then used to stabilize the hand and the instrument on the patient. The finger rest should be preferably established intraorally, as close as possible to the working area. A good modified pen grasp and finger rest permit excellent control of an otherwise potentially dangerous instrument. Improper probe handling may lead to soft tissue injury, as well as to misdiagnosis of periodontal lesions.
|
 Fig. 6 : Modified pen grasp. © Gracis
|
The periodontal examination includes the evaluation of tooth mobility, furcation lesions (or furcal invasion), gingival recession and hyperplasia, probing depth, presence of dental plaque, calculus and gingivitis (Table 1) (Magnusson et al, 1992). All data should be recorded on a dental chart, which should be designed to allow detailed description of periodontal and non-periodontal oral and facial structures (figure 7).
|
Fig. 7 : The front page of the canine dental chart as used in the Dental Department of the Veterinary Hospital of the University of Pennsylvania (USA).
This chart allows recording of all data concerning oral and periodontal examinations of animals. The other side of the same sheet is reserved for treatment description and post-operative evaluations. Printed with permission.
|
Tooth mobility
Tooth mobility is directly correlated to the amount of alveolar bone loss, however it is not an indicator of active disease. Tooth mobility is assessed by pushing the coronal tip of the tooth with the tip of the periodontal probe in a bucco-lingual/palatal direction, and in a vertical direction. A scale from 0 to 3 (Lindhe, 1983) or 0 to 4 (Rateitschak et al 1989) is used to measure tooth mobility. Normally teeth are stable or, like the mandibular incisor teeth, slightly mobile (mobility grade 0).
It is important to note that the size and number of roots greatly influence tooth mobility. 3 mm of bone loss may cause severe mobility of a first premolar tooth, but mobility may be clinically undetectable if the same amount of bone is lost around a canine or a three-rooted tooth such as the maxillary fourth premolar.
|
Furcation
The furcation is the area between the roots of multi-rooted teeth. This area is usually filled by alveolar bone, so that only a small depression may be felt by running the tip of the periodontal probe perpendicular to the tooth crown, just below the gingival margin (figure 8). When periodontitis occurs, the furcation bone may is resorbed and the probe may be introduced between the roots. Furcation defects are measured using a scale, grades 0-3. (Magnusson et al, 1992; Rateitschak et al, 1989). In case of a grade 3 lesion, the probe goes freely through the furcation, from the buccal to the lingual/palatal aspect of a tooth (table 2). It is important to perform the measurements on both the buccal and the lingual/palatal sides of a tooth, as bone destruction may develop asymmetrically.
|
Fig. 8 : Probing for furcal invasion is performed by running the tip of the periodontal probe perpendicular to the tooth surface, just below the gingival margin. © Gracis
|
Sulcus and periodontal pocket
The gingival sulcus is the space between the free gingiva and the tooth crown. In dogs, the depth of the gingival sulcus should be less than 3 mm. When periodontitis develops, the area of the gingival tissue that attaches to the tooth surface, the junctional epithelium, migrates apically along the root. If this apical migration is unaccompanied by gingival recession, this results in the formation of a so-called periodontal pocket, defined as being deeper than 3mm. If the gingiva recedes, the periodontal destruction does not usually result in the formation of a periodontal pocket.
|
Gingival recession
Gingival recession is measured in millimetres from the cemento-enamel junction (CEJ), where the gingival attachment should normally be, to the gingival margin (figure 9) (Rateitschak et al, 1989). The deepest measurement for each tooth is recorded on the dental chart.
|
Fig. 9 : 2 mm gingival recession on the buccal side of a left maxillary canine tooth. © Gracis
|
Probing depth
Probing depth is defined as the distance between the free gingival margin coronally and the junctional epithelium apically. It is measured by positioning the tip of the periodontal probe parallel to the long axis of the tooth (or following the crown's contour in case of teeth with a prominent "enamel bulge") and is gently inserted in between the tooth and the free gingiva until the bottom of the sulcus is felt (figure 10) (Rateitschak et al, 1989). In dogs the sulcus depth should normally be less than 3 mm deep, but measurements may vary greatly among dogs of different breeds and even amongst teeth of the same animal. Also, probe diameter greatly influences the ability to introduce the tip in the gingival sulcus. It is therefore very important to purchase a thin instrument. However, attention should be paid as the tip may perforate the junctional epithelium if excessive force is applied to a thin probe when measuring the probing depth. Inflamed tissues are particularly easy to penetrate (Jansen et al, 1981).
|
|
Fig. 10 : 2 mm gingival sulcus of a left maxillary canine tooth. © Gracis
|
In summary, probing technique, probing force, size of the probe and oral tissues health greatly influences the ability to measure probing depth (Newman et al, 1990). Some authors prefer to register clinical attachment loss or clinical attachment level (distance from the cemento-enamel junction to the bottom of the pocket) rather than individual recession and probing measurements. The importance of a 4 mm periodontal pocket reading where 5 mm of gingival recession exists (i.e. a total of 9 mm of attachment loss) is obviously different from that of a 4 mm pocket without any gingival recession (figure 11). As the gingival level and bone height may be irregular, it is recommended to take measurements at four to six sites per tooth, namely the mesio-lingual (palatal), the lingual (palatal), the disto-lingual (palatal), the mesio-buccal, the buccal and the disto-buccal sites. The progressive loss of clinical attachment is the most objective measurement that enables assessment of the progression of periodontitis in humans (Greenstein et al, 1998).
|
|
Fig. 11 : 5 mm probing depth and 3 mm gingival recession of a left maxillary canine tooth, totalling 8 mm of clinical attachment loss. © Gracis
|
Hyperplasia
Normally the junctional epithelium is positioned near the cemento-enamel junction. In cases of gingival hyperplasia when excessive amounts of soft tissues are present, a so-called pseudopocket develops. Gingival hyperplasia is measured similarly to probing depth, and is defined as the distance between the gingival margin and the junctional epithelium (figure 12). As areas deeper than 5 mm are difficult to mechanically clean, deep pockets and pseudopockets may need to be eliminated surgically, depending upon the amount of home care that can be expected (see Chapter 3). It is very important to consider that in cases of gingivitis the tissues may be oedematous and may appear enlarged. Treating gingivitis will automatically resolve the problem and surgical treatment can be avoided. If gingivectomy is erroneously performed, gingival recession will develop once the inflammation resides.
|
Fig.12 : Gingival hyperplasia on a left maxillary canine tooth, with a > 10 mm pseudopocket. © Gracis
|
Usually, only the single worst measurement of gingival recession and hyperplasia, probing depth (or attachment loss) and furcal invasion is recorded (figure 7), but it is possible to record all dental data. (Rateitschak et al, 1989).
|
Accumulation of dental deposits (plaque and calculus) and the severity of gingivitis can be measured by utilizing standardised indices that are a numerical expression of presence or absence and severity of pathology (Rateitschak et al, 1989). These indices are particularly useful in epidemiological studies, or when the evolution of periodontal disease needs to be assessed in the same animal. Plaque and calculus accumulation may be scored for coverage and/or thickness on any tooth (Logan et al, 1994; Hennet, 1999). Bleeding on probing, which is indicative of an inflammatory process in the connective tissues within the junctional epithelium, is a particularly useful method of evaluation of active gingivitis (Greenstein et al, 1998).
However, it should be noted that excessive probing forces might induce bleeding even in healthy sites.
|
|
