An update on radiation caries

Maintenance care

All HANC patients require close follow-up with a focus on prevention owing to the life-long increased risk of dental disease.^6,18 The initial recall interval based on NICE guidance is 3 months, although this may later be altered based on the patient's risk assessment.²⁸ Patients experiencing late complications may require longer-term follow-up within a specialist environment. However, where the patient has been rehabilitated and demonstrates stable oral health, they may be discharged to primary care for maintenance.^6,7 The initial interval for radiographic monitoring for the purpose of caries detection is 6 months, which may be increased to 12 months if long-term stability is evident.²⁹

Presentation of radiation caries

The presentation of caries tends to differ in those who have received radiotherapy. It presents as atypical lesions affecting surfaces normally resistant to caries including incisal edges, cusp tips, lingual and smooth surfaces, likely due to the lack of mechanical cleansing from salivary flow as a result of hyposalivation. The most common type of radiation caries affects the cervical surface and progresses circumferentially at the cementoenamel junction (CEJ) eventually resulting in decoronation.³⁰ Breslin and Taylor¹⁰ identified that mandibular incisors and canines were most commonly affected by radiation caries, followed by the maxillary incisors and canines. However, this was likely to be a result of fewer posterior teeth as these are more commonly extracted pre-radiotherapy.

Management of radiation caries

Management of radiation caries should aim to reduce the risk of osteoradionecrosis (ORN) by avoiding extractions in irradiated sites. ORN is commonly defined as an area of exposed devitalized bone, in a previously irradiated field, in the absence of neoplastic disease (Figure 1).³¹ Teeth should be retained wherever possible, which may include the need for root canal treatment, retention of roots or decoronation. Primary care dentists may provide routine restorative treatment, but where there is no suitable alternative, it has been recommended for extractions to be referred to secondary care.^6,32

The restoration of teeth in those with radiation caries is not without its challenges, particularly as patients may present with extensive atypical lesions and trismus. Composite resin, resin-modified glass ionomer and amalgam restorations perform more favourably than glass ionomer cements. However, in those with poor adherence to fluoride regimens, glass ionomer cements may be preferred owing to a reduced rate of recurrent caries at the expense of regular maintenance and replacement.³³ Caries should be managed conservatively initially with direct restorations. Indirect restorations may be considered in patients who are stable with a good level of oral hygiene.⁶

Case 1

A 67-year-old male diagnosed with a T4N3M0 basaloid squamous cell carcinoma (BSCC) that affected the skin posterior to the right ear was referred, following surgery, to the restorative team for a dental assessment prior to chemoradiotherapy.

The patient presented with a minimally restored, periodontally stable lower arch and an upper complete denture. A pre-operative orthopantomogram (OPG) was taken (Figure 2a). Extraction of the heavily restored LL7 was promptly arranged. Oral hygiene advice was given and 5000ppm fluoride toothpaste prescribed.

The patient was reviewed 2 months post-radiotherapy, presenting with a dry mouth, and a salivary replacement spray was prescribed. Despite regular reviews, reinforcement of oral hygiene advice and high-fluoride toothpaste, the patient attended with a decoronated LR4 14 months later (Figure 3a). Clinical examination revealed poor oral hygiene, viscous frothy saliva and caries affecting the remaining dentition (Figure 3b, c). Peri-apical radiographs confirmed extensive caries (Figure 2b). A dental clearance was performed, followed by provision of a new complete upper denture and immediate lower denture.

Case 2

A 63-year-old male patient diagnosed with a right tongue base T4N2M0 squamous cell carcinoma (SCC) was seen for a dental assessment prior to chemoradiotherapy.

The patient was an infrequent dental attender. An OPG was taken to assess the dentition (Figure 4a). The UR8, UL6, LL8, LR7 and LR8 were extracted. High-fluoride toothpaste and 0.05% fluoride mouthwash were prescribed.

The patient failed to attend his scheduled review. He attended 12-months post radiotherapy reporting multiple broken teeth. Clinical and radiographic evaluation revealed grossly carious teeth (Figure 4b). A full clearance was arranged and complete dentures constructed.

Case 3

A 66-year-old male diagnosed with a T1N1M0 BSCC of the left tonsil was seen for a dental assessment prior to chemoradiotherapy.

The patient had fair oral hygiene and a heavily restored dentition. Multiple extractions, including the LR7, were performed. The patient lived a considerable distance from the secondary care service and the general dental practitioner (GDP) was asked to complete full-mouth ultrasonic debridement, prescribe high-fluoride toothpaste and replace the LR6 crown due to marginal deficiencies (Figure 5a).

The patient failed to attend his post-therapy review and presented 17 months later with pain in lower right quadrant. Peri-apical radiographs demonstrated caries affecting multiple teeth (Figure 5b). A gingivectomy followed by root canal treatment of the LR5 and LR6 was performed to avoid extraction and the risk of osteoradionecrosis (Figure 5c).

Case 4

A 58-year-old male patient with a T3N1M0 right tongue base SCC was managed with surgery and adjuvant chemoradiotherapy. He was referred 17 months later to the restorative dentistry department by the ear, nose and throat (ENT) team due to extensive dental caries.

The patient had a dry mouth with poor oral hygiene and caries affecting multiple teeth. Oral hygiene advice, high-fluoride toothpaste and fluoride mouthwash were given, followed by direct restoration of carious teeth. Over the course of several years, secondary caries compromised the restorability of the teeth and those of hopeless prognosis were extracted (Figure 6a, b). A lower partial acrylic denture with stainless steel clasps was constructed. Porcelain metal crowns were provided for the UR7, UR3, UR2, UR1, UL1, UL2, UL3 and UL7 with guide planes and rest seats allowing the provision of a cobalt–chrome denture (Figure 6c). This functioned well for several years until the remaining lower teeth developed caries and required extraction. A complete denture was constructed, and the patient was functioning satisfactorily with the dentures.