Sir, it is worrying that the article by Liedholm et al.: Third molar treatment outcome: a comparison of patients' preferences in Sweden and Wales (BDJ 2005; 199: 287–291) includes, amongst its criteria for wisdom tooth removal, worsening incisor imbrication.

Wisdom teeth DO NOT cause this crowding, as evidenced by a previous Bristol study where on one side the wisdom teeth were present, but on the other side were either congenitally absent or had been removed. There was no difference between crowding on the two sides!

We have all seen a tiny upper nine preventing eruption of the maxillary wisdom tooth above it. How illogical therefore to assume that a wisdom tooth could 'push' the seven teeth in front forwards! Worsening incisor imbrication is a significant finding but NOT an indication for wisdom teeth removal. It may reflect late orthodontic relapse, or uprighting of incisors caused by tongue retroposition, when Spheno-occipital synchrondrosis activity elongates the skull base (continuing between the ages of 18-25 years). However, the commonest cause today is exaggerated mesial drift resulting from a tooth clenching habit. This is the forerunner of temporomandibular joint pain dysfunction problems.

Failure to recognise this connection wastes the opportunity of early corrective treatment, while removal of the wisdom teeth diverts the patient's attention away from addressing the real cause. As of course also happens with later temporomandibular joint surgical intervention! With all signs and symptoms, we much correctly interpret, such that it is possible to treat the cause; not merely the symptoms.

Rolf Liedholm, the author of the article, responds: I will emphasise that worsening incisor imbrication was NOT presented as a criterion for wisdom tooth removal. It was intended for patients to imagine experiencing the outcome described in a vignette. The reason for including it was to allow patients to assess the weight of an often discussed issue and as a matter of fact still considered of interest by some clinicians. The results showed, both in Sweden and Wales, that the vignette comprising the information 'lower front teeth which had been more squashed together' had a very low impact on patients' life. This can be interpreted as patients will not suggest wisdom tooth removal for this reason which is well in accordance with my opinion.