Tooth Structure

Attrition

Evidence: High Tooth Structure Reading time: approx. 5 min. Reviewed: 06.08.2026 · KEERN Editorial Team

Attrition is the loss of tooth hard tissue caused by direct tooth-to-tooth contact, distinct from erosion (chemical) and abrasion (external friction). A certain amount of attrition is a normal part of aging and increases gradually over decades; bruxism is by far the most common cause of accelerated, non-physiological wear. The Tooth Wear Index (Smith and Knight, 1984) remains the most widely used tool for assessing its extent, alongside newer systems such as TWES 2.0 that are increasingly used in research and specialist settings.

Related terms:BruxismDental erosionAbrasionEnamel

Definition

Attrition is the loss of tooth hard tissue caused by direct tooth-to-tooth contact: the wear that happens when biting and chewing surfaces meet during chewing, swallowing, or grinding. This sets it apart from erosion, chemical acid attack without friction, and from abrasion, wear caused by external objects such as a toothbrush.

This distinction matters conceptually, but in practice, isolated attrition is relatively uncommon. Most patients present with a combination of attrition, erosion, and abrasion, each contributing to the overall pattern of wear. Acid-softened enamel is generally more susceptible to mechanical wear, which is one reason erosion and attrition often reinforce each other.

Some degree of attrition is normal and increases over a lifetime simply through everyday chewing. This physiological wear typically unfolds over decades. Bruxism, repeated grinding or clenching of the teeth, accelerates it considerably.

Why visible wear is not automatically a warning sign

Visible wear on the teeth is often assumed to be a sign of disease. In most cases, a slow, even progression with age is a normal physiological process, similar to other everyday wear the body experiences over time. What matters is not whether attrition is present, but its speed and extent relative to age.

Causes

  • Normal chewing function, a continuous, lifelong process at a low level
  • Bruxism, repeated grinding or clenching, by far the most common cause of accelerated, non-physiological attrition
  • Missing or unbalanced tooth support, such as from missing back teeth

Possible consequences of pronounced attrition

  • Increased sensitivity to cold and heat once dentin becomes exposed
  • Changes in bite height in pronounced cases
  • Aesthetic changes, such as shortened or flattened biting edges
  • Loss of occlusal anatomy, which may affect chewing efficiency in advanced cases

What helps

  • Dental monitoring over time, particularly if wear is progressing unusually fast
  • Assessment and, where needed, management of bruxism as the most common accelerating cause
  • Where dentin is already exposed, a dental assessment of protective or restorative options

Key takeaways

  • Attrition results from tooth-to-tooth contact, unlike erosion (chemical) or abrasion (external friction), though the three frequently occur together
  • Some attrition is a normal part of aging, not automatically a disease, and typically unfolds over decades
  • Bruxism is the most common cause of accelerated, non-physiological attrition
  • What matters is the speed and extent of wear, not simply its presence
  • Rapid progression or new symptoms are worth a dental assessment

Frequently Asked Questions

Is attrition always a problem?

No. Some degree of attrition is a normal part of aging. It becomes a concern only with unusually fast progression or noticeable symptoms.

What is the difference between attrition, abrasion, and erosion?

Attrition results from tooth-to-tooth contact, abrasion from external friction such as toothbrushing, and erosion from chemical acid attack without friction. All three frequently occur together and reinforce one another.

Does bruxism always cause severe attrition?

Not necessarily to the same degree in everyone, but bruxism is considered the most common cause of accelerated, non-physiological attrition.

Can attrition be stopped?

Physiological wear cannot be completely prevented. Accelerated wear caused by bruxism or other factors can often be slowed if the underlying cause is addressed.

How much tooth wear is considered normal?

There is no single, universally agreed threshold. What matters more than an absolute amount is whether the wear looks appropriate for someone's age or clearly exceeds it. A dentist can make that comparison during a routine exam.

Can lost tooth structure grow back?

Lost tooth structure does not regenerate once true tissue loss has occurred, neither enamel nor dentin. Early mineral loss, before that point is reached, can sometimes be remineralized. Identifying the underlying cause early makes catching that window more likely.

How is the extent of attrition assessed?

Dentistry uses standardized indices such as the Tooth Wear Index (Smith and Knight, 1984) and newer systems such as TWES 2.0, which systematically evaluate different tooth surfaces.

KEERN Perspective

Attrition is a good example that not every change in a tooth is automatically a problem.

Oral health also means being able to tell normal aging apart from developments that actually need treatment, and that judgment belongs with a dentist.

Attrition reminds us that not every change deserves treatment, but every change deserves understanding.

Professional perspective

Clinical relevance

  • Distinguishing physiological from non-physiologically accelerated attrition
  • Differential diagnosis against erosion and abrasion, frequently presenting as a mixed picture
  • Bruxism screening in cases of unusually fast or atypical wear
  • Assessment of bite height in pronounced cases

Clinical implications

Attrition increases continuously with age and is, to some extent, considered physiological. The clinically relevant question is the discrepancy between observed wear and what would be expected for a given age: wear that is atypically pronounced for someone's age points toward an underlying cause, bruxism above all.

Isolated attrition is relatively uncommon in practice. Acid-softened enamel is more susceptible to mechanical wear, so patients with erosive dietary or reflux-related exposure often show faster progression when attrition or abrasion is also present; the combined pattern, not any single mechanism, typically drives the clinical picture.

Bruxism itself is internationally defined as repetitive jaw-muscle activity involving clenching, grinding, bracing, or thrusting of the mandible, occurring during sleep or while awake. Distinguishing sleep from awake bruxism can inform how a patient is screened and managed, since the two forms differ in presentation and assessment approach.

Classification: tooth wear indices

The Tooth Wear Index (TWI), introduced by Smith and Knight in 1984, remains the most widely cited general index for tooth wear regardless of cause. It grades attrition, erosion, and abrasion together, without differentiating between them, across four surfaces per tooth on a five-point scale. This distinguishes it from BEWE, developed specifically for erosive wear.

The 2017 European Consensus Statement on the management of severe tooth wear recommends TWI, BEWE, or the newer Tooth Wear Evaluation System (TWES 2.0) as assessment options, depending on clinical purpose. TWES 2.0, introduced in 2020, separates quantification of wear severity from identification of its likely cause. It is increasingly used in research and specialist settings, where its added diagnostic detail can justify the extra time it takes to apply; general practice more often continues to rely on the original TWI.

Physiological versus pathological

Attrition increases continuously with age and is considered physiological within a certain range. Clinically, what matters is the discrepancy between the observed extent and what would be expected for a given age: attrition that is atypically pronounced relative to age points toward an underlying cause, bruxism above all.

Evidence summary

What current evidence supports

  • Attrition increases continuously with age and is considered physiological to a certain extent
  • Bruxism, internationally defined as repetitive jaw-muscle activity during sleep or wakefulness, is the most common cause of accelerated, non-physiological attrition
  • Isolated attrition is uncommon in practice; it typically occurs alongside erosion, abrasion, or both
  • The Tooth Wear Index (1984) remains the most widely used general assessment tool, and multiple indices are recommended internationally depending on clinical purpose, per the 2017 European Consensus Statement

What remains uncertain

  • No single, universally accepted threshold exists for classifying age-related attrition as pathological
  • No index specific to attrition alone has achieved the validation and broad adoption that BEWE has for erosion
  • Which combination of indices best balances diagnostic detail against time and practicality in everyday clinical use remains debated

Smith and Knight (1984), in the British Dental Journal, introduced the original Tooth Wear Index, still the most frequently cited general index for tooth-wear research regardless of underlying cause.

Loomans et al. (2017), in the Journal of Adhesive Dentistry, published the European Consensus Statement on managing severe tooth wear, recommending TWI, BEWE, and TWES as assessment options depending on purpose.

Wetselaar et al. (2020), in the Journal of Oral Rehabilitation, introduced TWES 2.0, distinguishing quantification of wear severity from identification of its underlying cause.

Lobbezoo et al. (2018), in the Journal of Oral Rehabilitation, established the international consensus definition of bruxism, distinguishing sleep and awake forms.

Sources

📚 Smith BGN, Knight JK (1984): An index for measuring the wear of teeth. British Dental Journal, 156(12), 435-438.
📋 Loomans B, Opdam N, Attin T, et al. (2017): Severe Tooth Wear: European Consensus Statement on Management Guidelines. Journal of Adhesive Dentistry, 19(2), 111-119.
📚 Wetselaar P, Wetselaar-Glas MJM, Katzer LD, Ahlers MO (2020): Diagnosing tooth wear, a new taxonomy based on the revised version of the Tooth Wear Evaluation System (TWES 2.0). Journal of Oral Rehabilitation, 47(6), 703-712.
📋 Lobbezoo F, Ahlberg J, Raphael KG, et al. (2018): International consensus on the assessment of bruxism: Report of a work in progress. Journal of Oral Rehabilitation, 45(11), 837-844.

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The KEERN Lexicon provides evidence-based educational information about oral health. It is intended to support, not replace, individual advice from a dentist, physician, or pharmacist. Diagnosis and treatment decisions should always be based on a personal clinical assessment.