Clinical Scenario

A 54‐year‐old male with a head and neck cancer history presents to the dental clinic complaining that his teeth keep ‘crumbling’ and he is finding it difficult to eat.

Structured Learning

1. This patient currently resides in Spain but is of mixed heritage, with the maternal side of his family originally from China. How is this relevant to his diagnosis of NPC?
   • Although NPC is rare in most parts of the world, it is relatively common in South‐East Asia
   • Chinese populations, living either in mainland China or elsewhere, have the highest incidence of this tumour worldwide

   

2. What is the most likely cause of this patient’s limited mouth opening?
   • Radiotherapy of NPC typically delivers a considerable radiation dose to the temporomandibular joint (TMJ) region and related muscles
   • Trismus results mainly due to fibrosis of muscles of mastication; reduction in the TMJ disc thickness has also been noted
   • This does not present immediately but occurs progressively as mucositis subsides
   • The severity of trismus is dependent on the radiation source, dose and number of fields radiated
   • This patient received 60 Gy of radiotherapy – this is a considerable dose, despite the likelihood that intensity‐modulated radiotherapy was used
3. How is the diagnosis of trismus confirmed and what is the treatment of choice?
   • Diagnosis of trismus is clinical; it is typically made when the maximum interincisal distance between the incisal edges of the maxillary and mandibular incisors is <40 mm, regardless of its aetiology
   • For edentulous patients, the distance is measured between the maxillary and mandibular alveolar ridges
   • Some authors have graded trismus according to visual assessment of restricted mouth opening (mild/moderate/severe or grades 1–3)
   • Imaging adjuncts may be useful to establish its aetiology and determine the articular involvement of the TMJ
   • Computed tomography may be useful to identify traumatic aetiologies, including haematomas or facial and mandibular fractures when suspected
   • This condition can be managed by adapting the diet (softer foods cut into smaller pieces), jaw exercises, physical therapy devices (e.g. Therabite^®), using drugs (e.g. muscle relaxants, pain relievers, anti‐inflammatory medication, botulinum toxin) or, in advanced cases, surgery
4. The patient reports difficulties with eating and occasionally chokes on his food; this has been more pronounced in recent months. Fibreoptic laryngoscopy has demonstrated food residues in the oropharynx, reaching the entry to the airways. What is the most likely diagnosis and what complications can this lead to?
   • Late radiation‐induced dysphagia
   • This condition is due to progressive fibrosis caused by the ionising radiation that was absorbed by the cricopharyngeal muscle and oesophagus
   • The condition can cause malnutrition, an increased risk of aspiration, anxiety and depression and deterioration in quality of life
5. The patient has severe xerostomia. What is the impact of this and how would you manage it?
   • Xerostomia has promoted the onset of caries, affected oral function and consequently reduced the patient’s quality of life (QoL) (Figure 13.2.2)
   • Acknowledge the physical and psychosocial impact and implement supportive strategies
     

     

   • Advise the patient to stop using lemon sweets to stimulate flow as these will promote further tooth surface loss/caries
   • Prescribe fluoride toothpaste to help stabilise the teeth
   • A saliva substitute should be administered that provides symptomatic relief, such as hydroxyethyl cellulose, hydroxypropyl cellulose or carboxymethyl cellulose
   • Consider systemic salivary stimulants, such as pilocarpine (5–10 mg/8 h)
   • Consider referral for psychological support if there is significant depression/negative impact on QoL

6. What factors are considered important in assessing the risk of managing this patient?
   • Social
     • The information provided to the patient should be adapted to take into account his medical training
     • Hearing impairment
     • Psychosocial impact of cancer diagnosis and complications of cancer therapy
   • Medical
     • Sequelae of radiotherapy and chemotherapy
     • Poor prognosis of NPC – stage III NPC has an overall 5‐year survival rate as low as 30% (compared to 60–85% for patients with stage I or II NPC)
     • Capecitabine‐associated side‐effects
     • Appropriate selection of drugs
   • Dental
     • Postradiotherapy sequelae: oropharyngeal dysphagia with occasional choking, profound xerostomia, trismus
     • High risk of dental caries due to xerostomia, use of acidic lemon sweets to stimulate flow, and gastro‐oesophageal reflux
     • Multiple carious lesions and deteriorating dentition (Figure 13.2.3)
     • Determine the prognosis for the remaining teeth and design a treatment plan which considers his reduced likelihood of long‐term survival
7. The #33 and #34 are non‐vital and have extensive subgingival caries. What are the considerations for management of these teeth?
   • Capecitabine is an antimetabolite chemotherapy drug and may be associated with side‐effects such as leucopenia, thrombocytopenia and anaemia, in addition to nausea, vomiting and fatigue
   • A full blood count test result is required prior to proposed dental treatment
   • Depending on the results and general profile, haematological support (e.g. platelets) and antibiotic prophylaxis may be considered
     

     

   • The success rate for endodontic treatment is poor due to limitations in access, inability to create a good coronal seal and potential complications of bleeding and increased infection risk; crown lengthening may be considered to improve restorability but the patient may not be able to tolerate this additional procedure
   • However, dental extractions are associated with the additional risk of osteoradionecrosis (ORN) (Figure 13.2.4
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