Background: Tooth discolouration can be caused by a variety of local and systemic factors. Extrinsic dental stains may be caused by predisposing factors, and other factors such as dental plaque, foods and beverages, chromogenic bacteria, metallic compounds and medications. Studies have reported a correlation between the colour of extrinsic staining and caries risk.
Case report: A 4-year-old boy with West syndrome, characterised by epileptic seizures and severe muscle spasm, was referred to the paediatric dentistry clinic at School of Clinical Dentistry, Sheffield. He had a percutaneous endoscopic gastrostomy (PEG) tube and had no oral food or fluid intake. The presenting complaint was his parent's concern of trauma to the oral tissues from epileptic fits. An examination revealed an unusual navy-blue staining to his teeth that appeared extrinsic in nature. There was evidence of tooth-wear of his primary dentition, and marked calculus deposits. No caries was detected.
Treatment: A further dental examination and treatment was carried out under general anaesthesia. The mandibular central incisors were extracted, due to imminent pulp exposure from bruxism, and were sent for histopathology to determine the nature of the staining. A moderate growth of Pseudomonas aeruginosa, a blue pigment-producing bacteria usually implicated in chronic pulmonary infections, was recovered from a swab sample.
Follow-up: The patient was reviewed at 4 months at which time the staining had returned.
Conclusion: The patient had no oral intake of food or drink, which placed him in a low caries risk category despite limited oral hygiene practice. His extensive lists of medications were not found to have extrinsic dental staining as a possible side effect. However, these may have altered the oral flora such that growth of pigmented bacteria, normally absent from the oral cavity, was favoured, causing generalised extrinsic staining.