Enamel dysplasia and defects in young dogs we see commonly. If generalised it is also described as enamel hypocalcification or “distemper teeth”.
The lesions in the photographs are in a defined ring round all the teeth, roughly the same distance from the gingival margin. The owner was concerned and thought the teeth were sensitive as the dog eats strangely and occasionally drops food.
Questions:
- Likely aetiology?
- Significance of lesions?
- Plan of action and treatment options?
Enamel is the hardest substance in the body and only covers the crown of teeth (cementum does the same job on the root). Enamel is 99% inorganic and its job is to protect the underlying dentine. It is formed by cells called ameloblasts before the tooth erupts into the mouth. Once eruption happens these cells are no longer available for subsequent repairs. Enamel has no blood supply so it cannot inflame and it cannot repair – it is important to know that because the only repair possible for enamel is artificial.
Enamel provides a hard, smooth, impervious and protective cover to the crown. If it is lost the underlying dentine is exposed. Dentine is less hard (but still harder than bone) and is tubular, so comparatively rough. The tubules in dentine contain sensory nerve ending from cells in the pulp - 40,000 every square mm – so very sensitive. The tubules can also allow bacteria to enter the pulp from the mouth. Finally, because dentine is rougher on the surface than enamel, it allows plaque to attach and stains quickly – hence the brown colour. In humans over 30 years old, tooth sensitivity (to cold water, ice cream, hot tea) is common and most often due to normal enamel wear.
Aetiology: these lesions are likely to be historic from an illness many months previously when the dog was a pup. The fact that they are all the same distance from the gingiva leads us to believe they are systemic. This occurs most commonly when pups have a pyrexic period when the ameloblasts are making enamel at 8 - 14 weeks old. When Distemper was common in the UK, these lesions were found on the teeth of pups that survived to adulthood.
Another systemic manifestation is seen when all the teeth are covered in poor quality or flaky enamel because the of hypocalcification or hypoplasia of the enamel matrix. This is relatively common in Yorkies and other toy breeds. It is probably inherited.
Treatment: In general our approach is to hand scale the teeth gently to remove any unattached enamel first. Ultrasonic scaling is too brutal for these teeth unless an iM3 42-12 is used.
Once down to viable enamel and exposed dentine, each tooth needs fissure sealed to close off the tubules. We use a variety of materials depending on severity. Some need acid etched and some do not. All modern materials require light curing with a special gun.
Prognosis and Homecare: The biggest contribution the owner can make is with daily tooth brushing using a soft brush and a chlorhexidine based paste (HS Pet Care Chlorhexidine Paste). Dental plaque will attach to these teeth more readily and CHX is the most powerful agent we can use to remove it. In some cases we advocate the use of a Stannous Fluoride paste (HS Pet Care Fluoride Gel) twice a week to improve sensitivity. Fluoride hardens enamel and desensitises dentine. It can be toxic if swallowed so must only be used as directed by the vet - twice weekly at most.
The sealant will probably not last much longer than one year at best – maybe less. In some cases we re-seal a year later. Our feeling is that, as the teeth mature, tertiary dentine is laid down internally in preference to secondary dentine. This makes the teeth much less sensitive as they age. Fluoride varnish painted onto teeth after scaling and polishing also helps (Duraphat: Colgate).
Enhanced oral hygiene – both professional and at home - will be necessary for the rest of their life. Hand scaling and polishing may be necessary annually.
Finally, the brown colour is stained dentine and does not easily come off. This means the teeth will feel less sensitive but will not look pearly white. If owners want to show the dog they need to be aware of that.