Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now

×

Oral examinations under anaesthesia

Often an assessment of a patient’s whole dental arcade can only be obtained under anaesthesia so that underlying pathologies do not go untreated or misdiagnosed

As discussed in part one of this series on oral examinations in small animals, dental examination of the conscious patient is always limited. As such, it is often only once a patient is anaesthetised that a full picture can be obtained, and radiography is often essential for a complete assessment.

Consent forms

It is important to have a suitable consent form in place for your dental procedures. This will provide the owner with an idea of the likely procedures and costs; however, maintaining flexibility is paramount. While we always attempt to contact clients if the procedure has to vary from the original plan, our consent form details a window of up to an additional 20 percent of the estimated costs without further consent. For any variations above that amount, we are contracted to attempt contact through a single mobile number, and we require a single responsible adult, empowered to make decisions, to be available. We are not contracted to call multiple phones, or await the decision of a conference call between interested parties before a decision is made. If a decision maker is not available, the signed consent form permits us to proceed according to what we feel is in the patient’s best interests, and attests that the client is contracted to pay. During the procedure, we make contemporaneous notes on the client-patient record and record any calls made to the owner. No approach is fool-proof, but we hope that this provides all sides with a suitable level of protection.

Examination

With some patients, it is only after sedation or full anaesthesia that examination is possible: the muzzled “close-protection guard dog” is a classic example. However, a closer examination of even the most placid Cavalier King Charles Spaniel will be more easily achieved under anaesthesia. Typically, it is the most caudal parts of the arcade, the occlusal (biting) surfaces and the inner palatal and lingual surfaces that can be difficult to examine in the conscious patient. Do not forget that the labial frenulum and the position of the tongue can effectively hide the mandibular first and second premolars. As unerupted first premolars are often associated with the development of dentigerous cysts, it is important to ensure a careful head-count of the dentition is performed when anaesthesia makes access easier.

Probing

Bob Partridge Figure (1) The dental probe is one of the most important tools used in oral examinations

One of the most important tools to use in dental examination is the dental probe (Figure 1).

At its most basic usage, the probe extends the reach of the examination into the back of the mouth so that soft tissues can be prodded and assessed, sinus tracts can be investigated and the mobility of teeth can be determined. There are, however, a couple of specific areas where the probe comes into its own.

Furcation exposure

Figure (2) An F3-level furcation exposure is indicated by a through-and-through passage of a probe

The furcation is the area at the junction of the roots of a tooth. Exposure of the furcation implies a loss of the alveolar bone, usually as a result of periodontal disease, and furcation exposure is classified by probing the furcation area (Table 1). In most cases where periodontal disease has resulted in so much bone loss as to represent an F3 classification, it can be regarded as an indication for extraction (Figure 2).

Furcation exposure
F0Normal – no furcation exposure
F1Probe can enter the furcation area – but to a depth of less than 50 percent
F2Probe can enter more than 50 percent – but not right the way through
F3Through-and-through passage of the probe
Table (1) A dental probe is used to determine the degree of furcation exposure

Periodontal pocket depth

Pocket depth has long been an important assessment of the health status of a tooth (Table 2). The periodontal probe is carefully inserted into the gingival sulcus and the depth of the pocket, from the tip of the gingival margin to the bottom of the sulcus, is measured.

NormalModeratePoorSevere
CanineLess than 3mm3mm to 5mm5mm to 7mmMore than 7mm
FelineLess than 0.5mm0.5mm to 1mm1mm to 2mmMore than 2mm
Table (2) Pocket depth measurements can be used to assess the health of a tooth

It is important to note when measuring pocket depth that different probes use different spacing markings, so be sure you know exactly how you are measuring and remember that it is easy to incorrectly measure the depth. Applying too much force will drive the probe down through healthy tissue, giving an inaccurately high reading of the pocket depth. The pressure applied should be standardised to 20gm. Practising probing on a set of scales helps to remind everyone just how little force is required, and helps to ensure that standardised readings are obtained throughout the practice. There are some “second generation” probes that give a pressure indication when in use (Figures 3A and 3B). These can also be a great training aid; however, the standard WHO probe has a 0.5mm ball at the tip which can render it useless for feline patients.

It is also important to assess whether any bleeding results from the probing process as “bleeding on probing” is usually an indicator of a degree of periodontal disease. Teeth should have their periodontal pockets probed around the whole tooth, with ideally four or six measurements taken. Good electronic dental charting systems will allow the collection of all of this data, but if you are recording only a single number, then record the deepest pocket.

However, pocket depth without any context can be a misleading measurement. For example, consider cases of gingival hyperplasia. In these cases, a pocket depth of 10mm or more may be recorded. However, the area involving the alveolar bone to tooth interface is actually relatively normal. Appropriate gingival surgery will quickly restore a degree of normality, which would be at variance from the expectation generated by the recording of such a deep pocket depth. Conversely, in the situation of gingival recession a small pocket depth would not imply periodontal health.

Stage 0Normal
Stage 1Gingivitis 1-2No attachment loss
Stage 2Early periodontitisLess than 25 percent attachment loss1st signs destructive periodontitis
Stage 3Moderate periodontitis25 to 50 percent attachment lossIncreasing bone loss
Stage 4Severe periodontitisMore than 50 percent attachment lossOften irreversible
Table (3) Periodontal disease is classified according to the percentage of tooth attachment loss

A far better measurement of oral periodontal health status relies on assessing the degree of attachment loss – the loss of the area of bone support for a tooth (Table 3).

The probe can also be used to assess the mobility of teeth (Table 4). While a root fracture in the cervical area will lead to great crown mobility, the most common cause of mobility is advanced periodontal disease and loss of the supporting alveolar bone (Figures 4A and 4B).

Tooth Mobility
M0Stable, physiologic movementLess than 0.2mm
M1Slight movement in any direction – apart from axial0.2mm to 0.5mm
M2Moderate0.5mm to 1mm
M3Severe – any axial movement (“in/out” movement along the line of the tooth)More than 1mm
Table (4) The classification of tooth mobility varies depending on the direction and amount of movement

Shepherd’s hook

Bob Partridge Figure (5) The shepherd’s hook, or “explorer”, is used for oral examinations and can be found at the opposite end to the periodontal probe on many instruments

Conveniently situated at the opposite end to the periodontal probe on many instruments is the shepherd’s hook, or “explorer” (Figure 5).

The most common use of this instrument is to assess areas for possible dental pulpal exposure. For example, where a tooth is subject to gradual wear – such as the dreaded tennis-ball wear – as the tooth structure is destroyed, the pulp retreats away from the wearing surfaces by laying down tertiary (or reparative) dentine (Figure 6A). This dentine is less well organised and tends to acquire staining, leading to a dark coloration which can be difficult to differentiate from the appearance of exposed necrotic pulp. Running an explorer over the surface will either lead to the sharp tip dropping down into a pulp canal (Figure 6B), or skating across the smooth tertiary dentine surface.

Figure (7) Soft, damaged and poorly attached enamel is indicative of enamel dysplasia

The explorer is also useful in assessing the integrity of the enamel. Areas of soft, damaged or poorly attached enamel can be detected in cases of enamel dysplasia (Figure 7). Problems with enamel development can occur due to genetic causes, episodes of pyrexia during the development (which occurs solely before the tooth erupts) and, most commonly, trauma. This should act as a reminder to exercise extreme care when extracting temporary teeth to avoid damage to the developing adult tooth buds.

Figure (8) Compromised enamel integrity can result from dentine decay in caries

Caries represents another pathology in which the integrity of the enamel is compromised, allowing the underlying dentine to be subject to decay (Figure 8).

The explorer can also be used to detect otherwise almost invisible fractures. Careful assessment of the crowns can sometimes reveal small hairline cracks which can represent significant underlying pathologies (Figures 9A and 9B).

Conclusion

A careful, thorough assessment of the whole dental arcade is often only possible under anaesthesia. Findings should be recorded on suitable software, or paper records. This helps to ensure that pathologies do not go untreated and the response to therapy can be assessed.

However, no dental assessment is complete without the use of radiographs. This will be the subject of the third article in this series.