Research Reports first published in the journal Tuith Online

The management of carious primary teeth using pre-formed metal crowns: The Hall Technique

A peer reviewed paper titled "The Hall technique: a pilot trial of a novel use of preformed metal crowns for managing carious primary teeth" was reported in this e-journal in December 2000. The pilot study having shown the feasibility of using the technique in the surgery, a clinical trial is now underway in the Tayside area. Nicola Innes here describes progress during the first two years of the trial (up until October 2003).

Background to the study

There is a high decay rate in the teeth of Scottish children (mean of decayed, missing, and filled teeth, dmft, = 2.55 in 5-year-olds) combined with a low care index (filled teeth as a percentage of dmft) of 10% (further details). The Hall technique may be a simple way of managing decayed primary molars. We know from the pilot trial, previously published, that the technique is easy to carry out and acceptable to patients, parents, and dentists.
A detailed description of the Hall technique can be found in the previous article but, in a nutshell, it involves cementing a preformed metal crown (PMC) using glass ionomer cement onto a primary molar, with no occlusal tooth reduction or mesio-distal preparation and no caries removal.

Aim

The trial will determine the clinical effectiveness of the technique in managing carious primary molars in the primary care setting of general dental practice.

Design

The study is a centrally randomised controlled strategy involving 16 dentists all working in general practice who are recruiting patients from their normal patient base.
In order to be eligible to enter the trial, children must be 4-9 years old, have matched carious lesions in contralateral Ds or Es, and bitewings of good diagnostic quality. Measurements are taken at enrolment, and then each tooth is treated by placement of a PMC on one side and a conventional filling of the dentist's choice on the contralateral tooth. Which tooth is treated first and which side has which restoration is determined by central randomisation. Recordings are taken at 1 year and 2 year recall and all emergency and routine treatments carried out in between are also being documented.

Current status

Because the recruitment criteria for entry are very strict, it has taken much longer to enrol patients into the trial than was initially anticipated. However, in order to maintain the integrity of the study, the stringency of the criteria has been upheld. We aimed to have 150 children in the trial and are finally getting close to that number (145 as I write; October 2003). 78 children have returned so far for their 1st yearly recall and the dropout rate would appear to be low.
6 patients have also completed the 2nd year of the cycle. All of the dentists in the trial are well established in their practice and were felt to have a stable patient base. It is hoped that this low dropout rate will continue throughout the second year of follow-up.

Discussion

When I first began to organise this trial (I am a GDP and had obtained funding from the Chief Scientist Office to investigate the Hall technique) and asked other researchers about running a clinical trial, I was painted a very bleak picture by almost everyone I spoke to. This study was considered to be especially unlikely to succeed in its aim because it was based in general practice and would be relying on GDPs. However, I think this may have been a bit too pessimistic. In 2000, letters were sent to all 153 dentists in Tayside and replies expressing interest in taking part were received from 61. This was an unexpectedly good result as we were only looking for 10 initially. Recruitment of patients, despite being slow, is continuing well and the 1st yearly recalls appear to be successful. I am indebted to all the dentists who are taking part in the study as they have been assiduous in completing the forms and are taking excellent quality bitewing radiographs. I think that part of the reason for this success is that the dentists themselves can see the obviously relevant nature of the research question: "Do PMCs perform better in general practice than conventional filling techniques?" and its importance to their everyday practice.
We hope to present some definitive results within the foreseeable future.