Pathology · patient case with 1 question
Root caries in a patient receiving radiotherapy for testicular cancer
Scenario: A patient with TESTICULAR CANCER receiving RADIOTHERAPY has caries at the roots of his teeth. All of the following are causes EXCEPT one.
Question 1
All of the following could cause his root caries EXCEPT:
Show answer and explanation
Correct answer: A. The radiation therapy itself
- A. Correct — this is the EXCEPTION, and the reasoning is anatomical. 'Radiation caries' occurs because radiotherapy to the HEAD AND NECK damages the SALIVARY GLANDS, producing xerostomia and loss of salivary buffering, clearance and remineralisation. Radiotherapy directed at the TESTES does not irradiate the salivary glands, so it cannot be the cause of this patient's root caries.
- B. Poor oral hygiene allows plaque accumulation at the gingival margin, the site where root caries begins.
- C. A cariogenic diet supplies fermentable carbohydrate for acid production and is a direct cause regardless of the cancer diagnosis.
- D. Gingival recession exposes CEMENTUM and root dentin, which demineralise at a higher critical pH (around 6.0-6.7) than enamel (5.5) and are therefore far more caries-susceptible.
Note: The point of this item is that the FIELD OF RADIATION determines the oral effects. Head and neck radiotherapy causes xerostomia, radiation caries, mucositis, trismus and OSTEORADIONECROSIS; radiation to a distant site does not. CHEMOTHERAPY, by contrast, has systemic oral effects (mucositis, myelosuppression, opportunistic infection) regardless of the site treated.