2.5 Tooth Surface Loss & Tooth Discolouration
Key Takeaways
- Erosion is chemical dissolution without bacteria, attrition is tooth-against-tooth wear, abrasion is wear by an exogenous agent such as a toothbrush, and most clinical wear is multifactorial
- Palatal erosion of the upper anterior teeth with sparing of the labial surfaces points to an intrinsic acid source such as gastro-oesophageal reflux, an eating disorder or rumination
- The Dahl concept uses a localised anterior bite platform to create interocclusal space by relative axial tooth movement, avoiding elective removal of sound posterior tooth tissue
- Under UK cosmetic products law, whitening products releasing more than 0.1% and up to 6% hydrogen peroxide may only be supplied to dental practitioners, may not be used on anyone under 18, and the first cycle of use must be carried out by the dentist
- Internal bleaching of a non-vital tooth requires a cervical barrier placed about 1 to 2 mm below the cemento-enamel junction to reduce the risk of external cervical resorption
Classifying Tooth Surface Loss
Tooth surface loss (TSL) is the non-carious loss of dental hard tissue. Four processes are described, but almost all clinical wear is multifactorial and the value of the classification is that each component suggests a different preventive action.
| Process | Mechanism | Typical appearance |
|---|---|---|
| Erosion | Chemical dissolution by acid without bacterial involvement | Smooth, shiny, cupped occlusal surfaces; "islands" of amalgam standing proud; loss of palatal enamel on upper anteriors |
| Attrition | Tooth against tooth | Flat, matching wear facets on opposing teeth; shiny facets on restorations |
| Abrasion | An exogenous agent — toothbrush, abrasive paste, pipe stem, hairgrips | V-shaped or notched cervical lesions, worst on the canines and premolars of the dominant hand's side |
| Abfraction | Proposed cervical flexure under occlusal loading | Wedge-shaped cervical lesions; the mechanism remains contested, so do not attribute wear to it without excluding erosion and abrasion |
Erosion: intrinsic versus extrinsic acid
| Source | Examples | Pattern |
|---|---|---|
| Intrinsic | Gastro-oesophageal reflux disease, hiatus hernia, eating disorders with vomiting, rumination, hyperemesis of pregnancy, alcohol dependence | Palatal surfaces of upper anteriors, occlusal surfaces of lower molars; labial surfaces relatively spared |
| Extrinsic — dietary | Citrus fruit and juice, carbonated and sports drinks, vinegar-based foods, wine | Labial and buccal surfaces; distribution follows how the drink is held in the mouth |
| Extrinsic — occupational or environmental | Professional wine tasting, competitive swimming in poorly buffered chlorinated pools, industrial acid exposure | Widespread, often labial |
| Extrinsic — medication | Chewed vitamin C or aspirin tablets, acidic iron preparations | Localised to the site where the tablet is held |
Palatal erosion with labial sparing is the pattern that should prompt tactful enquiry about reflux and about vomiting, and referral to a GP for reflux investigation or to the appropriate service where an eating disorder is suspected.
Measuring and Monitoring
The Basic Erosive Wear Examination (BEWE) scores the most affected surface in each sextant from 0 to 3 and sums them (0–18): 2 or less indicates no risk, 3–8 low risk, 9–13 medium risk and 14 or above high risk.
Monitoring matters more than any single measurement, because the decision to restore turns on whether wear is active:
- Study casts at baseline and at intervals, ideally with a date written into the cast.
- Clinical photographs in standardised views.
- Silicone index taken over the worn surfaces, allowing later comparison.
- Repeat BEWE and record it.
Managing Tooth Surface Loss
- Identify and remove the cause. Dietary advice on frequency and on how drinks are consumed; reflux referral; do not advise brushing immediately after an acid challenge — wait, and rinse with water or a fluoride mouthrinse instead.
- Protect and desensitise. High-fluoride toothpaste, fluoride varnish, and where appropriate a soft splint at night for parafunction.
- Monitor if wear is slow, the patient is asymptomatic and aesthetics are acceptable.
- Restore when there is sensitivity, functional loss, aesthetic concern or a risk of pulpal exposure. Adhesive composite build-ups are the usual first-line, being reversible and repairable; onlays and crowns are reserved for extensive loss.
The Dahl concept
Localised anterior tooth wear leaves no interocclusal space in which to place restorative material. Historically the answer was elective crown preparation of sound teeth or an increase in the occlusal vertical dimension across the whole arch. The Dahl concept avoids both: an anterior bite platform (composite build-ups or a removable appliance) is placed so that only the anterior teeth occlude, and over subsequent months relative axial tooth movement — posterior eruption combined with some anterior intrusion — re-establishes posterior contacts.
- Typically re-establishes posterior occlusion within 3–6 months, occasionally longer.
- High reported success in patients with a healthy periodontium and no active temporomandibular disorder.
- Patients must be warned to expect a period with only anterior contacts, altered chewing and possible lisping.
- Less predictable in patients with reduced periodontal support, previous orthodontic treatment or implants in the posterior segments, because implants do not erupt.
Tooth Discolouration
| Type | Causes | Management |
|---|---|---|
| Extrinsic | Tea, coffee, red wine, tobacco, chlorhexidine, iron supplements, chromogenic bacteria (black stain in children) | Scaling and polishing, air polishing, cause removal |
| Intrinsic — pre-eruptive | Tetracycline (banned in pregnancy and under 12 for this reason), fluorosis, amelogenesis and dentinogenesis imperfecta, erythroblastosis fetalis, porphyria | Microabrasion, bleaching, veneers or crowns depending on severity |
| Intrinsic — post-eruptive | Pulp necrosis and intrapulpal haemorrhage, pulp canal obliteration after trauma, internal resorption, root filling materials, amalgam and metallic corrosion products, ageing | Internal bleaching after satisfactory root treatment, or restorative masking |
Microabrasion with 18% hydrochloric acid and pumice removes a very thin surface layer and is effective for superficial fluorotic and demarcated opacities; it is destructive of enamel, so it is used sparingly and combined with fluoride afterwards.
Tooth whitening and the law in the UK
Tooth whitening is regulated as a cosmetic product, and the rules are frequently examined:
- Products containing or releasing more than 0.1% and up to 6% hydrogen peroxide may only be sold to dental practitioners.
- For each cycle of use, the first use must be carried out by the dental practitioner or under their direct supervision; the product may then be supplied to the patient to complete the cycle.
- These products must not be used on anyone under 18 years of age for cosmetic purposes. Whitening a discoloured non-vital incisor in a younger patient may be lawful where it is genuinely for the treatment or prevention of disease, but the justification must be recorded.
- Products releasing more than 6% hydrogen peroxide are not permitted for cosmetic tooth whitening.
- 10% carbamide peroxide, the classic home-bleaching concentration, releases approximately 3.6% hydrogen peroxide and therefore sits within the permitted range.
- Illegal whitening by non-registrants is both a cosmetic-products offence and, where it constitutes the practice of dentistry, an offence under the Dentists Act.
Expected side effects — transient sensitivity and gingival irritation — must be part of the consent discussion, along with the fact that existing restorations will not change colour and may need replacing afterwards.
Internal (non-vital) bleaching
Used for a discoloured, root-treated anterior tooth with an adequate root filling and no periapical pathology. The key safety step is a cervical barrier of glass ionomer or resin-modified glass ionomer placed about 1–2 mm below the cemento-enamel junction, sealing the dentinal tubules of the cervical region. Without it, peroxide can reach the periodontal ligament through the tubules and precipitate external cervical resorption — the recognised serious complication of the technique.
A 32-year-old has smooth, shiny loss of enamel on the palatal surfaces of all six upper anterior teeth with cupping of the lower molars. The labial surfaces are largely intact and he has no dietary acid intake of note. What should the clinician suspect and do first?
A patient has localised wear of the palatal surfaces of the upper incisors with no interocclusal space for restorative material. The periodontium is healthy and there is no temporomandibular disorder. Which approach avoids removing sound tooth tissue from the posterior teeth?
A 16-year-old with a discoloured, root-filled upper central incisor asks about whitening. What is the correct position under UK cosmetic products law?
What is the purpose of the cervical barrier placed before internal bleaching of a non-vital tooth, and where should it sit?