Introduction 1 3 7 17 There is some debate within the dental academic community on the appropriateness of terminology. Many academics recognise the term tooth wear as encompassing erosion, attrition and abrasion. However, other researchers focus upon acid erosion often using the term to describe what others would call tooth wear and use the term erosion in a context which others might not agree. Whilst the definitions of erosion, abrasion and attrition are accepted, the relative importance of these causes is not. Therefore, in this paper both terms are used where appropriate to convey meaning interpreted by many researchers working in this field. Tooth wear and erosion 4 29 26 9 8 1 2 10 Fig. 1 The wear on the occlusal/incisal surfaces of the upper anterior teeth. The wear is caused by a combination of erosion and attrition. The “cupped out or ditched” areas result from the action of acids, whereas the flatter surfaces are caused by attrition  Fig. 2 The wear on the palatal/lingual surfaces of the teeth has been caused by regurgitation erosion. It is unlikely that abrasion or attrition has contributed to the process  Prevalence 20 24 22 24 24 23 25 25 17 3 1 7 25 25 20 14 Progression of tooth wear 18 23 25 . 16 19 20 19 16 5 2 13 21 28 6 21 28 Pathological tooth wear 18 23 25 11 12 23 27 25 25 15 25 3 17 20 25 25 The hypothesis that pathological tooth wear is age related depends on who is assessing the impact. State health care authorities, private insurance schemes, industry, dentists and patients all have different interpretations on what is pathological and what is not. For patients, loss of enamel could be considered pathological particularly if they are focussed upon the appearance of their teeth, whereas dentists may consider intervention is needed when dentine is involved, but their capacity to treat is affected by the limitations of restorative materials. On the other hand, state health care providers may take a much longer term view, with the assumption that a tooth remains functional, if not aesthetic, when operative care is not imperative. Based on the current data, it is too challenging to suggest that tooth wear is an age-related phenomenon. There is some justification to this hypothesis based on the current data from children, adolescents and adults. Clinical experience suggests that as adults age they tend to develop more wear on the occlusal and incisal surfaces of teeth. It is likely, therefore, that some progression of wear on teeth is age related. However, this assumption needs investigating. Evidence partly from prevalence studies and partly from accurate measurement of tooth wear by profilometry tends to give support to this hypothesis. It must be remembered, however, that the prevalence studies at best report on just over 1,000 subjects. This is extremely small considering the populations involved. Tooth wear indices remain the most convenient and reproducible method to grade severity but are limited by incompatible criteria. It is imperative that a consensus is developed to build a simple and reproducible index, used by researchers so that data on the prevalence of tooth wear, particularly in adults, can be investigated. Conclusion 25 3 17 25