This letters was published in the journal Tuith Online in December 1999

Pip Thomas tells us why he thinks GDPs should get involved in research and what they can expect to get out of it

Pip Thomas tells us why he thinks GDPs should get involved in research and what they can expect to get out of it.

I have been involved over a number of years in two research projects which have been practice based, the most recent as lead name. Both projects have been co-ordinated and run by the Colgate Dental Health Unit in Manchester which is a clinical research unit, an essential prerequisite to any meaningful practice-based research project. I obtained my MSc by thesis 25 years ago while a full time lecturer in the Manchester Dental School with an investigation into "the variation in plaque calcium and phosphate content in response to sucrose containing confectionery." A investigation which was almost entirely laboratory based, required little funding, and was closely supervised, in short it was of very limited use when dealing with practice-based clinical research.

The first step in establishing a clinical research project is a very tightly written protocol which sets out in great detail the means to be used in collecting the data and the safe guards to be employed in ensuring elimination of any inter and intra-examiner bias. Unless you possess the necessary experience and skill in writing such a protocol many hours will be wasted as one protocol after another is returned questioning methodology and demanding rewriting to answer yet another objection to the intend method of data collection, When the protocol is accepted by the funding authority the money will be granted and then the nuts and bolts can be assembled. Suitable subjects (patients) and examiners (dentists) have to be found, assembled, and paid for and equipment purchased, distributed, and training in its use arranged.

The data is then collected, suitably recorded, and subjected to statistical analysis; another highly skilled procedure for which allowance will have to have been made in the protocol. Very few dentists will have the necessary statistical skills and so the services of a suitable statistician will need to be employed. When all the data has been collected and analysed, the results discussed, and valid conclusions drawn, the research paper must be written and submitted for publication to a refereed journal. Even at this stage the paper may be rejected if the referees feel that the results are flawed.

The first of the projects in which I was involved was (conducted under the guise of) a toothpaste trial. In this a number of practitioners had to select between 100 and 200 patients each over the age of 25 with at least one tooth. The patients received one free examination a year as well as a years supply of toothpaste and toothbrushes. The dentists received the patients contribution to NHS exam fee, where appropriate, plus £5 a year for each patient. The patients were divided into control and experimental groups but as it was a double blind trial, only the research worker knew which was which. The experimental group was supplied with the tooth paste with the active ingredient while the control group's toothpaste did not. Each patient's mouth was initially fully charted to include all teeth and all teeth and all restorations present. From then on, all treatment over a five year period was recorded for tooth, tooth surface(s), material, and reason for placement. At the end of the trial it was revealed that the difference between the two toothpastes used in the experiment was in flavour only. Thus a difference between test and control was not anticipated and both sets of results could be combined to act as a survey of the dental status of mature adults; as opposed to children and young adults, for whom many such surveys existed.

The full project involved 4000 subjects (patients) and 20+ examiners (dentists). Meetings of the participating dentists were held once a year when interim results were discussed, it was only at the last meeting that the true nature of the study was revealed. What did we get out of the project? A lot of interest, a feeling of involvement, and some excellent hospitality at the Dental Health Unit, plus between £400 and £900 a year each. The patients were most interested and felt equally involved.

The second study involved the use of Fibre Optic Trans-Illumination (FOTI) to diagnose inter-proximal caries and is being funded by the NHS primary care R & D agency. Despite the fact that the protocol was written by the Dental Health Unit team, it was returned no fewer than three times for written clarification by the university clinical ethics committee with suggested modification to the methodology. Once the go-ahead was given, 4 practitioners were chosen and asked to provide up to 20 patients each with suitable carious lesions. The subjects had to be prepared to wait until after the data collection to have their lesions treated and all had to have bitewing x-rays available for inspection. The Dental Health Unit also provided a number of patients. The dentists had been supplied with FOTI probes in their surgeries for a number of weeks prior to data collection to allow familiarisation with the techniques.

On the day of the study, the dentists, accompanied by a dental surgery assistant, rendezvoused at the Dental Health Unit. Each dentist examined all patients. For some subjects, mirror, probe, and FOTI were used, whilst for others only the mirror and the probe were employed: the method whereby each cavity was identified (i.e. visual or FOTI). Bite-wings from the patients, which were displayed anonymously, were also examined and cavities recorded. The same patients were re-examined 3 weeks later. Meticulous examination of almost 80 patients, with lunch taken on the hoof, and reporting on as many pairs of x-rays is, mentally, very tiring. The patients received expenses and a fee and the dentists were paid the guild rate (£188 per half day). These costs, together with the purchase of the FOTI probes and statistical services amounted to around £10,000.

Everyone agreed that the FOTI probes were very useful and regretted having to hand them back at the end of the study, although modifications were suggested to make them easier to use. To date, the results of this study have not been fully analysed, but it is likely that they will form the basis of a further study.

There is a large pool of data in dental practices and a large number of able enthusiastic practitioners with, potentially, the necessary skill to make useful contributions to the dental knowledge base. If a body of practitioners with the necessary skills to conduct valid practice-based research projects is to be built up, however, they must be offered training and involvement in every stage of a project from conception to delivery, and not be merely involved as data collectors or as lead names by academic bodies wishing to gain access to NHS primary care R & D funding.

P.D.(Pip) Thomas is a GDP practising in Manchester