Management of Discoloured Teeth
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Direct answer
A single grey upper central incisor that went dark after a football injury is a different patient from a teenager with chalky-white and brown mottling across both arches: discolouration is classified as extrinsic (surface stains — tobacco, tea, chlorhexidine, chromogenic bacteria, iron syrups) or intrinsic (within enamel or dentine — fluorosis, tetracycline, pulp necrosis, dentinogenesis imperfecta, ageing), and the classification writes the treatment plan. Extrinsic stains polish or scale off; mild intrinsic fluorosis responds to microabrasion with 18% hydrochloric acid and pumice; vital bleaching uses 10% carbamide peroxide in a nightguard at home or 35–38% hydrogen peroxide in surgery; non-vital teeth receive the walking bleach with sodium perborate sealed between visits behind a cervical barrier. Veneers and crowns finish the ladder when bleaching cannot deliver.
What you must remember
- Extrinsic stains: tobacco and paan products, tea and coffee, chlorhexidine (brown), iron supplements in children (black), chromogenic bacteria (green or black in children) — removed by scaling, polishing and habit change.
- Intrinsic pre-eruptive: dental fluorosis (optimum water fluoride about 1 ppm; endemic belts of India such as Nalgonda, Rajasthan and Gujarat drink water far above this), tetracycline (yellow-grey bands, deposited on forming dentine; avoid in pregnancy and under 8 years), amelogenesis and dentinogenesis imperfecta, erythropoietic porphyria (reddish), neonatal jaundice (greenish bilirubin).
- Intrinsic post-eruptive: pulp necrosis and haemoglobin breakdown (grey-black), internal resorption (pink spot), ageing dentine, root canal sealers and historic silver nitrate medicaments.
- Fluorosis severity is graded by Dean's index (normal through questionable, very mild, mild, moderate, severe) — the classic exam classification — and by the TF index for finer coding.
- Microabrasion (Croll technique: 18% hydrochloric acid mixed with pumice) removes a very shallow layer of surface enamel for white and brown fluorosis patches and idiopathic opacities.
- Vital bleaching: nightguard vital bleaching with 10% carbamide peroxide (about 3.5% hydrogen peroxide) overnight for two to four weeks — introduced by Haywood and Heymann in 1989; in-office bleaching uses 35–38% hydrogen peroxide with light or heat activation.
- Non-vital (walking) bleach: sodium perborate mixed with water or hydrogen peroxide, sealed in the chamber and refreshed over visits; a cervical barrier of about 2 mm of glass ionomer at the cementoenamel junction level guards against external cervical resorption — the feared complication, especially with heat and trauma history.
- Tetracycline staining bleaches poorly (banding sits deep in dentine) — veneers or crowns are realistic; severe fluorosis and dentinogenesis imperfecta likewise.
Working through a non-vital discolouration
A 30-year-old wants the "dead-looking" upper left central incisor matched to its neighbours. The tooth turned grey two years after trauma; it is comfortable now, non-vital to thermal and electric tests, with a periapical radiograph showing either an intact lamina dura or early periapical change — either way, root canal treatment comes first, because bleaching an infected canal invites flare-ups. Complete the root canal, then cut the coronal gutta-percha back and seal a 2 mm glass ionomer barrier at the cementoenamel junction level. Mix sodium perborate with distilled water into a thick paste, pack the pulp chamber, and seal with a temporary zinc oxide eugenol or glass ionomer restoration, reviewing in about a week — refreshed until the shade overshoots slightly lighter than the neighbours. Protect the gingiva with petroleum jelly at each paste change, and finish with a composite seal of the access cavity. Consent mentions external cervical resorption as the rare late risk the barrier exists to prevent.
Where students slip
The dangerous slip is bleaching before diagnosis: a single dark tooth may be necrotic, resorbing internally (the pink spot), or cracked — each demands its own treatment first, and vitality testing plus a periapical film are mandatory before any bleaching tray or walking bleach. The second error is classification mixing: writing chlorhexidine or tobacco under intrinsic staining, or fluorosis under extrinsic, halves the theory answer instantly. Third is the barrier omission in walking bleach answers — the cervical glass ionomer plug is the specific fact that distinguishes a prepared candidate, being the direct countermeasure to external inflammatory root resorption. Fourth is overpromising on tetracycline staining: honest answers state the deep dentinal banding limits bleaching, moving instead to veneers or full coverage.
Frequently asked questions
How are discoloured teeth classified?
Extrinsic (surface deposits and stains) versus intrinsic (within enamel or dentine, subdivided into pre-eruptive such as fluorosis and tetracycline, and post-eruptive such as pulp necrosis and ageing).
What is the nightguard vital bleaching technique?
Home application of 10% carbamide peroxide gel in a custom tray, described by Haywood and Heymann in 1989, typically worn overnight for two to four weeks.
Why is a cervical barrier placed in walking bleach?
To seal the dentinal tubules and cementum at the cementoenamel junction with about 2 mm of glass ionomer, preventing peroxide tracking down the root and triggering external cervical resorption.
Which index grades fluorosis?
Dean's index — normal, questionable, very mild, mild, moderate, severe — with the Thylstrup–Fejerskov (TF) index for finer gradations.
Which discolouration responds worst to bleaching?
Deep tetracycline banding and severe dentinogenesis imperfecta, because the chromophore lies deep within dentine — veneers or crowns are the realistic options.