Root Caries

Root caries is a carious lesion starting on the exposed root surface of a tooth, at or apical to the cemento enamel junction. It is mainly a disease of older adults and increases as gingival recession, reduced salivary flow and medication use become more common.

Prevalence rises with age, with reports of about 40 to 60% of adults over 60 having at least one root lesion, and it is a major cause of tooth loss in older age.

Pathophysiology. Cementum and dentine are less mineralised than enamel and demineralise at a higher critical pH (about 6.2 to 6.7, compared with about 5.5 for enamel), so lesions develop with lower acid challenge.

Risk factors: gingival recession from periodontal disease or brushing trauma, hyposalivation from drugs (anticholinergics, antidepressants, antihypertensives, antihistamines, diuretics), Sjögren syndrome or head and neck radiotherapy, frequent sugar intake, poor plaque control, partial denture clasps, and reduced dexterity or cognitive impairment.

Soft, leathery or hard, yellow, brown or black discoloured areas on the root surface, often circumferential, near the gingival margin, with sensitivity to cold and sweet food, or no symptoms. Lesions can undermine the crown and cause fracture at the cervical margin.

Pulp involvement produces toothache, and infection produces abscess. Look for dry mouth, plaque, recession, dentures, medications, diet and the person's ability to brush.

• Visual and tactile examination of exposed root surfaces with a dry tooth and gentle probing. Active lesions are soft or leathery, rough and dull with plaque, and arrested lesions are hard, smooth and shiny.
• Bitewing radiographs for interproximal lesions, with periapical views if pulp involvement is suspected.
• Salivary flow: unstimulated rate under 0.1 mL/min and stimulated rate under 0.7 mL/min indicate hyposalivation. Medication review and, when dry mouth is unexplained, tests for Sjögren syndrome and diabetes.
• Diet and fluoride assessment, and caries risk assessment.
• Vitality testing and radiographs for a symptomatic tooth.

Differential diagnosis.

• Cervical abrasion, erosion and abfraction lesions
• Cervical external root resorption
• Hypersensitive exposed dentine without caries
• Staining of the root surface
• Secondary caries at crown or restoration margins
• Developmental defects of the cervical region

• Prevention and arrest are the first aims, with control of plaque and diet, and reduction of sugar frequency.
• Fluoride toothpaste 5000 ppm (1.1% sodium fluoride) applied twice daily in adults aged 16 years and over, replacing the usual toothpaste, with spitting and not rinsing. Toothpaste of 2800 ppm is an alternative. Add a fluoride mouthwash 0.05% daily, used at a different time of day.
• Fluoride varnish 5% sodium fluoride (22 600 ppm) applied every 3 to 6 months to exposed roots.
• Silver diamine fluoride 38% applied once or twice yearly to arrest active lesions, with warning of black staining of the lesion and a risk of soft tissue staining. Avoid with silver allergy and in open pulp exposure.
• Restoration of cavitated lesions, lesions that trap plaque, or those with sensitivity: resin modified glass ionomer or glass ionomer cement with selective removal of soft dentine. Composite is used in more accessible lesions. Pulp therapy or extraction is needed for pulp involvement.
• Dry mouth: review and change drugs with the prescriber, sugar free chewing gum or lozenges, saliva substitutes, and frequent sips of water. Pilocarpine 5 mg orally three times daily with meals (maximum 30 mg daily) for residual salivary gland function, started at 5 mg twice daily in hepatic impairment. Avoid in uncontrolled asthma, narrow angle glaucoma and severe cardiovascular disease, and with beta blockers because of conduction disturbance. Adverse effects include sweating, nausea and urinary frequency.
• Oral hygiene support: powered toothbrush, interdental brushes, and help from carers where dexterity or cognition is impaired.

Special groups. Head and neck radiotherapy needs lifelong daily high fluoride care, custom fluoride trays with 1.1% sodium fluoride gel for 5 minutes daily, and avoidance of extractions in irradiated bone without specialist planning because of osteoradionecrosis. Care home residents need regular dental review and carer training.

Monitoring. Review every 3 to 6 months for high risk adults, reassessing lesions for activity, plaque, saliva and diet. Update the medication review and caries risk status at each visit.

Referral and escalation. Refer to a restorative dentist or special care dentistry for extensive disease, complex medical conditions or inability to cooperate. Refer to oral medicine for hyposalivation without clear cause, and urgently to oral surgery for swelling, spreading infection or non-healing ulcers near a root surface.