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Evaluating Restorative Materials and Procedures in Dental Practice

F.J.T. Burke

Primary Dental Care Research Group, University of Birmingham School of Dentistry, St. Chad’s Queensway, Birmingham B4 6NN, UK; f.j.t.burke{at}bham.ac.uk

KEY WORDS: Dental practice • restorative • techniques

A wide variety of research methods are appropriate to general dental practice, including clinical trials of materials, assessment of materials and techniques, treatment trends, and assessment of behavior and attitudes, of dentists as well as patients. This paper will describe the use of practice-based networks to evaluate the effectiveness of materials and techniques in dental practice. Several practice-based research groups are presently in operation in the UK and the USA, generally carrying out evaluations of the handling of materials, but with increasing emphasis on the clinical evaluation of restorations. Use of the Dental Practice Board (of England and Wales) database has proved to be a fruitful source of data on the long-term outcome of restorations. Dental practice can provide the large pool of patients available for research. To utilize this pool of patients, dental practitioners and their support staff require training in collecting data.

	Introduction

TOP Introduction Discussion Concluding Remarks References

 
Practice-based research
It has been suggested, by Irwin Mandel, that "the major energy source for fuelling professional change and growth is research", but that practitioners tend to take this for granted (Mandel, 1993). However, it has also been suggested that research findings may not be published in a form that is user-friendly to practitioners, with half of respondents to a survey of Canadian dentists preferring a commentary on a series of abstracts or an article that translates research findings into practical guidelines (Allison and Bedos, 2003). This may have the potential to delay the implementation of their findings into clinical practice. Research methodologies such as meta-analyses, systematic reviews, or randomized clinical controlled trials are unlikely to be used by general dental practitioners, since these require knowledge of statistics and research methodology which are not generally within the practitioner’s grasp. However, randomized clinical trials and retrospective and prospective clinical evaluations may readily be carried out in dental practice, where the patient base is likely to be substantially greater than in dental schools or hospitals. Moreover, the patient base in dental practice represents patients of various patterns of attendance, from different walks of life, and different levels of oral hygiene and caries experience, whereas patients in dental hospitals may not be considered to represent a typical patient population, since they generally elect to attend such institutions because they have the time available for treatment by students (i.e., the retired or unemployed) and may often have attended for many courses of treatment, in which their oral hygiene will be reinforced (i.e., their oral hygiene may be better than that in the general population).

Goodman (1993) has considered that prospective studies are preferred to retrospective ones, controlled studies are preferable to uncontrolled ones, randomized studies are preferable to non-randomized ones, blind studies in which patients (single-blind) or patients and investigators (double-blind) do not know who received what treatment are preferable to unblind ones, and large studies are preferable to small ones. However, the time required to perform the "ideal" clinical assessment may make some of these techniques less than ideal for general dental practice, given the rapid turnover of new dental materials. However, a wide variety of research methods are appropriate to general dental practice. These include (Burke and McCord, 1993):

• clinical trials of materials,
  
• assessment of materials and techniques,
  
• assessment of treatment trends and treatment of disease,
  
• assessment of behavior and attitudes (of dentists as well as patients),
  
• evaluation of disease incidence, and
  
• patient satisfaction.
  

However, the ultimate question (for patients, dentists, administrators, and governments) must be, "How long do restorations last?"

Effectiveness of restorative materials and techniques
The success of a material or technique may be considered to be its performance in everyday use in a particular dentist’s office. It is increasingly possible to obtain such information from dental computer systems. Additionally, the volume of clinical material seen in general dental practice makes this an area of fundamental importance in the development of new techniques and the assessment of new materials. For clinical trials of materials, ideally, the population group should be representative of the population, and the comparison of the study and control groups should be double-blind, and there should be only a few drop-outs. Restorations should be followed up for at least three years.

In the past, success rates of restorations have been assessed by retrospective evaluation of patients’ records, as painstakingly described by Robinson (1971), Allan (1977), Paterson (1984), and others. This painstaking work in the precomputer era provided valuable information on restoration longevity, but about only one practitioner and his particular group of patients.

Practice-based research teams
To carry out the above work in dental practice, practitioners require training in the standardization of procedures, calibration in the assessment of restorations, and training in scientific methodology. All of this is possible when practitioner-based research groups are teamed with the expertise available in academic institutions, with this being a win/win situation for all. The academic institution is seen to be carrying out relevant research, while the practitioners have an additional interest, with the potential for improvement in the practice image.

There is, therefore, merit in the establishment of a research team, but it is likely that this will generally need the enthusiasm of one or more people to:

• identify interested parties,
  
• provide basic training in research,
  
• find suitable projects and funding, and
  
• get the research started.
  

The aim of the practice-based research group should ultimately be the identification of projects that are relevant to them, through completion and publication.

However, the practitioners should:

• not be paid ‘mercenaries’,
  
• not place restorations for money alone,
  
• have ownership over the project, and
  
• be equal partners with the established researchers—that is, each group has its own role to play.
  

One such group is the PREP (Product Research and Evaluation by Practitioners) Panel. This group was established in 1993 with six general dental practitioners, and has grown to include 25 practitioners UK-wide. It has completed 40 projects—mainly "handling" evaluations of materials and techniques, but also, clinical evaluations of restorations of novel materials (Crisp and Burke, 2000; Burke et al., 2005). The studies are often sponsored by manufacturers, and the results are published.

BRIDGE (Birmingham Research in Dental General PracticE) is another practice-based research group, based at the University of Birmingham School of Dentistry. This group, which was established in 2000, has approximately 20 members and holds four meetings per year at which ideas for new projects are put forward and discussed. Four unfunded and two funded projects have been completed, and the group is currently collecting data for the project that won funding from the Shirley Glasstone Hughes Award at the British Dental Association in 2002. Among the projects discussed at recent meetings of BRIDGE were the effect of changing to rectangular collimation, job satisfaction in the dental profession, and factors influencing longevity in Class V restorations and resin-retained bridges.

A West of Scotland-based practitioner research group, GRID (Glasgow Research Initiative in Dental Practice), was founded in 1997 by a few general dental practitioners who had attended a lecture on research in dental practice, and who subsequently responded to a letter inviting them to take part in practice-based research. The group used to meet four or five times per year, had approximately ten members, and completed several research projects (vide infra).

Some dental practitioners in Hong Kong have recently banded together and produced a "handling" evaluation of a resin-composite material, Esthet-X (Dentsply, Weybridge, Surrey, UK), using methodology similar to that utilized by the PREP Panel (Li et al., 2002). Other projects involving this group are ongoing.

Perhaps the best-known group of practice-based researchers is the Clinical Research Associates (CRA), founded by Gordon Christensen 30 years ago. This organization is funded by the sales from its CRA Newsletter and carries out practice-based evaluations of a wide range of dental materials, as well as laboratory assessments.

Most recently, groups of dental-practice-based researchers have been established in Scotland and in the Manchester area, with the aim of the latter network being to ally the practitioners to an academic department and develop the practitioners’ research interests into research skills and, ultimately, into a research project (Kay et al., 2003).

Use of practice-based networks to evaluate the effectiveness of materials and techniques in dental practice
The PREP Panel operates as follows for "handling" evaluations of materials. A manufacturer agrees to sponsor the project and co-writes a questionnaire designed to evaluate the handling of the material under test. The material is distributed to members of the Panel, who use the materials as indicated and complete the questionnaire. By this means, the manufacturer receives feedback on the handling of his company’s material by a group of UK dental practitioners.

Some "handling" evaluations have been extended to include clinical assessment of restorations over several years. In such studies, the PREP Panel member places the restoration under typical general practice conditions, carries out the baseline assessment, and arranges for the recall of the patient for examination by a trained and calibrated independent examiner, who examines the restorations using modified United States Public Health Service criteria, in combination with the panel member who placed the restoration. The mode of failure, if any, is recorded. Additionally, in some investigations, photographs are taken of a representative proportion of restorations, and a patient questionnaire on comfort/performance of the restoration is completed. Both patient and practitioner are reimbursed for their expenses, with the time for which the practitioner’s surgery is tied up during the patient examinations being the principal expense incurred by the practitioner. Since the members of the PREP Panel are geographically diverse, budgetary constraints mean that the independent examiner can visit each locality for only one or two days. Although patients must be able to attend on those specific days, this does not appear to have an adverse effect on recall rates (Crisp and Burke, 2000; Burke et al., 2005).

Other groups have enlisted practitioners in clinics without dental schools to participate in research into restoration longevity, without identifying the researchers under a particular name. For example, Jan van Dijken has assessed 182 large ceramic restorations in 110 patients, with 7.1% being assessed as non-acceptable after a mean period of 4.9 years (van Dijken et al., 2001). This is an excellent example of how a variety of practicing conditions may be utilized to produce meaningful results on the success of novel restorative techniques.

Cross-sectional studies have also been used in general dental practice to produce useful, meaningful results, with Ivar Mjör being the principal advocate of this research methodology (Deligeorgi et al., 2001). These studies have the advantage, over randomized controlled clinical trials, of producing data which may include large numbers of restorations in a wide variety of patients, placed by dentists with a wide variety of qualifications and experience. A recent example of this type of study has examined the effects of different methods of funding restorative care in the UK on restoration age at replacement, with restorations placed within the NHS being replaced at a lower age than restorations placed under the other funding arrangements investigated (Burke et al., 2002b). Another recent cross-sectional study investigated the influence of patient factors, such as oral hygiene status and caries susceptibility, on the age at which restorations were replaced (Burke et al., 2001a). These two studies were carried out by GRID, plus members of the Faculty of General Dental Practitioners (UK) who volunteered to participate, having responded to advertising in the Faculty newsletter.

The Big Picture: use of the Dental Practice Board of England and Wales (DPB) database to evaluate longevity of restorations
The principal function of the DPB, which is based in Eastbourne, Sussex, UK, is to process claims for payment by dentists providing NHS dental treatment in England and Wales, and to check the validity of such claims. This amounts to more than 45 million documents per annum (Dental Practice Board Annual Report 2001–2002). Work carried out by the senior statistician at the DPB has created a second, smaller database from which it is possible to "track" a proportion of the fillings placed from 1991 to the present, thereby providing longevity data and the factors influencing them. This investigation involves the records of 82,537 adult patients, who collectively received over half a million courses of treatment between 1 January 1991 and 31 December 2002. This would appear to be the largest database ever developed for research into restoration longevity, and it is anticipated that this work, the initial findings of which have been presented at research meetings (Lucarotti et al., 2002, 2003), will ultimately provide details of how restoration performance is influenced by patient factors (such as age, sex, and attendance pattern), dentist factors (such as age, practicing location, country of graduation), and restoration material (such as amalgam, composite, or glass ionomer).

	Discussion

TOP Introduction Discussion Concluding Remarks References

 
Why, in the past, did so little research originate from dental practice? A survey of three journals from the UK dental literature of 1991 showed that the percentage of publications relating to clinical techniques/materials was only 22%, and that only 9% of those articles had any general dental practice input (Morrow et al., 1995). Since the majority of dental treatment, worldwide, is carried out in dental practice, there is therefore an imbalance between treatment output and research output. This is possibly not surprising, since dental practices are established to provide effective and efficient treatment for patients, rather than to carry out research. Additionally, time spent on research may equate to lost income, and involvement of practitioners in research may produce a conflict of interest between the their principal responsibility to patients and the requirements of research (Wilson and Mjör, 1997).

It may be considered that dental practice should have an increasing impact on clinical dental research. Since dental practice is the ‘real world’, a technique or material must be acceptable to practice conditions for it to be successful. However, in the past, many clinical evaluations have been carried out on hospital-based patients, and these may not be valid for the following reasons (Mjör and Wilson, 1997):

• The patients may not be typical of those seen in dental practice (they may often be dental students).
  
• The treatment may be carried out by well-qualified academics who are less likely to be subjected to the pressures of time and cost-effectiveness that prevail in dental practice.
  
• The clinicians may be working as part of a team which has received pre-operative instructions in the handling and use of the materials under investigation.
  

New materials and techniques should ideally be assessed in the practice situation, since this is the predominant arena in which the materials and techniques will be used. It is essential that all new materials have a minimum of one year’s clinical data before being released for use in general dental practice. All failures should be recorded.

Critics of practice-based research have commented on the lack of calibration of operative diagnoses and other uncontrolled variables (Wilson and Mjör, 1997). These comments may sometimes be valid and should be discussed when the results are reported. However, this variability is the real-world situation. In summary, advantages of practice-based research include:

• real-world/uncontrolled nature of the research,
  
• a more realistic patient base,
  
• different "angle" from academics, and
  
• additional interest for the staff.
  

Additionally, for the practitioner who becomes involved in research, there is the additional benefit of involvement in something not normally within the daily routine of dental practice. In the past, it was suggested that patient co-operation and attendance for recalls could be a potential problem with practice-based research (Burke and McCord, 1993). More recently, however, it has been considered that patients (who are reimbursed for their involvement) are generally pleased to have been involved in a research project (Burke et al., 2002a). Furthermore, the dentist’s involvement in a research project has been thought to be a practice-builder (Mjör and Wilson, 1997).

One reported problem regarding practice-based research has been a lack of practitioner interest—for example, the depressing scenario recounted by Mackie, in which only a small proportion of the anticipated number of pairs of restorations were achieved (Mackie, 1998). However, a means of avoiding this situation may be to obtain the necessary funding and to integrate the practitioners fully into the development of the protocol (Burke et al., 2002a). Wilson and Mjör (1997) have considered that "the real challenge is to conceive and design studies which have a sound scientific basis and which are suited to the environment in which they are undertaken". There would appear to be evidence, from the formation of the practice-based research groups mentioned above and the variety of projects that may be appropriate to dental practice, that the importance of dental practitioner involvement in research is increasingly being recognized.

Finally, patients may increasingly demand information on the potential performance of a restoration. Practice-based research could go a long way toward providing such information. However, as practices are increasingly becoming computerized, the practice computer may ultimately become the means of recording restoration longevity. Indeed, this will provide patients with details of the success of a particular technique in their own practitioner’s hands, which may well be the "evidence" that patients want, but are often too shy to ask.

	Concluding Remarks

TOP Introduction Discussion Concluding Remarks References

 
Dental practice can provide the large pool of patients available for research. To utilize this pool of patients, dental practitioners and their support staff require training in collecting data. The importance of practice-based research has been emphasized by Mandel, who considered that "research is not only the silent partner in dental practice, it is the very scaffolding on which we build and sustain a practice" (Mandel, 1993). The establishment of practice-based research groups may contribute to the realization of this ideal, although there is also a need to change the thinking of the dental professional, so that the incorporation of practice-based research philosophy becomes the norm rather than the privilege of practice-based research groups.

	References

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