Discoloured tooth with an intact crown – do I need to worry?

In dogs, discoloured teeth with intact crowns are non-vital in majority (92.2%) of the cases. When these teeth are radiographed, they may show no signs of endodontic disease. In veterinary dentistry we still do not know, if such teeth are infected. In humans, microbes have been isolated from teeth with necrotic dental pulp and intact crowns in high number of cases (85%). Endodontic infections in such teeth are believed to be preceded by dental pulp necrosis, and bacteria can originate from infected periodontal pockets (controversial), microcracks in dental hard tissues, or exposed dentinal tubules. Dentinal tubules are 1 – 4 micrometers in diameter, while most bacteria are smaller than 1 micrometer. Bacteria can enter the dental pulp via blood or lymph (anachoresis), although this is believed not to contribute to disease significantly in humans, and there are no reports for cats and dogs.

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Similarly, we do not know, if discoloured non-vital teeth without pulp exposure are painful; oral/dental pain is in general in animals very difficult to be noted. Detailed oral examination and dental radiographs are therefore needed to evaluate discoloured teeth for any signs of endodontic disease (e.g., width of the pulp cavity, periapical lesion, inflammatory root resorption) in order to plan treatment accordingly. Computed tomography (CT) and cone-beam CT (CBCT) have proven superior in diagnosing endodontic disease and should be considered especially in cases, where endodontic disease is high on the differential diagnoses list, but dental radiographs fail to reveal any.

It is recommended to treat discoloured teeth – either with extraction or root canal treatment. Conservative approach with regular radiographic re-checks may be considered in cases with no radiographic signs of endodontic disease. However, due to the need of anaesthesia for radiographic re-checks, limitations of dental radiography and our inability to properly assess dental pain in animals, it is debatable if conservative approach is beneficial to the animals.

If you have noted any problems with your animal, please consult your veterinarian.

Selected references
1. Hale FA (2001). Localized intrinsic staining of teeth due to pulpitis and pulp necrosis in dogs. J Vet Dent;18(1):14-20.
2. Holan G, Fuks AB (1996). The diagnostic value of coronal dark-gray discoloration in primary teeth following traumatic injuries. Pediatr Dent;18(3):224-227.
3. Firmino Bruno K, Gonçalves de Alencar AH, Estrela C, de Carvalho Batista A, Pimenta FC (2009). Microbiological and microscopic analysis of the pulp of non-vital traumatized teeth with intact crowns. J Appl Oral Sci;17(5):508-514.
4. Lin LM, Di Fiore PM, Lin J, Rosenberg PA (2006). Histological study of periradicular tissue responses to uninfected and infected devitalized pulps in dogs. J Endod;32(1):34-38.