Sir, in an otherwise erudite research summary, Peter Crawford suggested that the paper Preformed metal crowns for carious primary molars, by Innes et al.,1 would become a landmark in the restorative care for children. I beg to differ. It should be pointed out that this is a retrospective study based on uncontrolled general dental practice records, and therefore not the sort of study that could be considered for evidence, based dentistry. Of greater importance, though, is the effect of this approach on oral care in children.

Undoubtedly, treating children can be challenging, even for specialists, and the promise of an easy solution to the difficulties must be very attractive to a harassed dentist. Historically, silver nitrate application, copper cement and the atraumatic restorative technique have all had their proponents and proselytising disciples, and have all been discarded as serious ways to deal with decay in primary teeth; perhaps ozone treatment will go the same way. They have all promised so much and yet delivered so little.

If Dr Hall can persuade her patients, without local anaesthesia, to tolerate the discomfort of biting a PMC into place through a tight contact and into the gingival crevice, then surely she could persuade them to tolerate the discomfort of an injection. Where approximating carious molars have spontaneous marginal ridge breakdown, as is acknowledged in the paper, not only is there almost certainly irreversible pulpal involvement which will require pulp therapy, but there is also going to be loss of mesial-distal space. This space-loss situation makes PMC fitting more difficult at the best of times, let alone without anaesthesia, and the resultant poorly-fitting buccal and lingual margins will lead to a chronic periodontal condition.

While it has been shown that a well-adapted fissure sealant has the potential to arrest superficial carious lesions, this is not the case for deep dentinal caries where substrate is available from the pulp. What does the Hall Technique do to arrest caries? If the answer is that it doesn't, then should it be used, at the very least from an ethical standpoint?

We acknowledge the wide gulf between paediatric dental restorative techniques recommended by specialist bodies and that provided by GDPs, but the answer must not lie in unproven expediencies. The Hall technique, like the atraumatic restorative technique, perhaps has a place in the field, in developing countries. Elsewhere it should merit only a passing mention.