Cracked Tooth Syndrome

Cracked tooth syndrome is an incomplete fracture of a vital posterior tooth that begins in the crown and extends toward the root, producing sharp pain on biting and release, or on cold exposure, without a visible fracture, caries, or periapical disease.

• Mandibular second molars are most often affected, followed by maxillary premolars and mandibular first molars; most patients are 30 to 50 years old.
• Causes: large restorations or amalgam fillings that undermine cusps, root canal treated teeth, bruxism and clenching, chewing hard foods or ice, deep occlusal grooves, steep cuspal inclines, tooth preparation, and extreme thermal changes.
• Progression: from an enamel or dentine crack with a vital pulp, to reversible pulpitis, irreversible pulpitis, pulp necrosis with apical periodontitis, and finally a split tooth that cannot be saved.
• Cracks cannot be seen on routine radiographs in most cases, and the diagnosis is often delayed for months.

• Sharp, brief pain on chewing, classically sharp on releasing the bite (rebound pain), especially with fibrous foods, seeds, or hard foods.
• Pain on cold, sweet, or hot food; the patient cannot always point to the tooth; intermittent over weeks to months; no pain at rest early on.
• Later signs of pulp involvement: lingering pain after hot or cold, spontaneous or night pain, pain on percussion, and gum swelling or a sinus tract with a deep narrow periodontal pocket.
• Examination: wear facets, large or failing restorations, deep restoration margins, a visible crack line (sometimes stained), a fracture line crossing marginal ridges, and no caries.
• Associated: bruxism, tooth clenching, and facial muscle tenderness.

• History of pain on release of biting with no other cause, then localisation with a bite test: ask the patient to bite on a cotton roll, wooden stick or specific device (Tooth Slooth) on each cusp individually; pain on release of the bite at one cusp is characteristic.
• Cold test (ice stick or refrigerant spray) and electric pulp test to determine pulp status; percussion and palpation.
• Visual examination: transillumination with a fibre optic light (the crack blocks light), dye staining (methylene blue 1 percent) to reveal crack lines, and magnification with a dental operating microscope.
• Periodontal probing: an isolated, narrow, deep pocket over the crack line suggests a vertical fracture of the root, with a poor outlook.
• Radiographs usually appear normal early; later show a widened periodontal ligament, radiolucency (bone loss) around the root, or a J-shaped or halo lesion; cone beam computed tomography has limited sensitivity for fine cracks.
• Differentials: caries, reversible or irreversible pulpitis, failing restoration, periodontal abscess, high filling, sinusitis (upper teeth), temporomandibular disorder, trigeminal neuralgia, dentine hypersensitivity, and atypical odontalgia.

Immediate relief and interim care

• Avoid chewing on the affected side and avoid hard, sticky and very cold or hot foods.
• Analgesia: paracetamol 1 g orally every 6 hours (maximum 4 g daily) with ibuprofen 400 mg orally every 8 hours with food (maximum 1.2 g daily without prescription; 2.4 g daily on prescription) for 3 to 5 days.
• Urgent referral to a dentist (within days) for diagnosis and stabilisation.

Dental treatment (determined by the pulp state and crack extent)

• Stabilise the tooth early: remove the old restoration to examine the crack, then cuspal coverage with an adhesive restoration, a full or partial crown (onlay or three quarter crown), or an orthodontic band as a temporary measure for several weeks to check whether symptoms resolve.
• Reduce occlusal contacts (cuspal reduction) on the affected tooth.
• Reversible pulpitis (cold pain that fades within seconds): cuspal coverage alone.
• Irreversible pulpitis or necrosis (lingering, spontaneous, night pain, or apical disease): root canal treatment followed by a crown with full cuspal coverage; success is good if the crack does not extend below the gum line.
• Crack extending into the root, or a split tooth with a deep isolated pocket: extraction and replacement (implant, bridge or partial denture).
• Antibiotics are not indicated unless there is swelling or spreading infection: amoxicillin 500 mg orally three times daily for 5 days, adding metronidazole 400 mg orally three times daily for 5 days if the infection is severe.
• Night guard (hard acrylic) for bruxism.

Prognosis and follow up

• Teeth treated early with cuspal coverage have survival of 80 to 90 percent at 5 years; cracks that reach the pulp floor or periodontal ligament have a poorer outlook; a crack that has caused a periodontal pocket usually needs extraction.
• Review 2 to 4 weeks after interim treatment, and again at 3 months, 6 months and then yearly; reassess the pulp status; monitor neighbouring teeth, which are also at risk.