M.H. Ree, M.F. Timmerman & P.R. Wesselink
Department of Cariology, Endodontology Pedodontology, and Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, the Netherlands.

Introduction.
It has been concluded from several studies (de Cleen et al. 1993, Saunders et al. 1997, Weiger et al. 1997, de Moor et al. 2000) that there is a substantial need for root canal treatment in the population and that a considerable amount of this need will be in the form of retreatment.
Longitudinal studies after root canal treatment have shown high success rates up to 96%for periapical health (Strindberg1956, Kerekes & Tronstad1979, Sjogren et al. 1990). However, many of these studies were undertaken on root canal treatments carried out in specialist clinics or at dental schools.
The success rates of endodontic treatment performed in general practice are substantially lower. Several cross-sectional studies amongst the population in different countries have shown a high rate of apical periodontitis associated with root filled teeth (22-61%) and a high frequency of radiographically inadequate root fillings (47-86%) (Odesjoet al.1990, de Cleen et al.1993,Eckerbom 1993, Buckley & SpBngberg 1995, Weiger et al. 1997, Saunders et al. 1997, Marques et al. 1998, de Moor et al. 2000, Kirkevang et al. 2000, 2001).
In order to improve the success rate in general dental practice it has been emphasized that undergraduate and continuing education in endodontics should be given more emphasis, and that the referral of difficult cases to dentists with advanced knowledge and training in endodontics should be made possible for the benefit of patients (de Cleen et al. 1993, Saunders et al. 1997, de Moor et al. 2000).
In a survey held amongst general practitioners (Saunders et al. 1999) it was shown that the decision to refer was influenced by certain factors. For example, the presence of a perforation was considered an important factor to refer by 87.1% of the respondents, followed by the need for retreatment (76%) and periradicular surgery (73.8%).
There have been no previous studies on the factors that may influence the decision to refera patient for endodontic treatment by general practitioners in the Netherlands. Therefore, the aims of this study were:

1. to analyse the need for endodontic referral amongst a group of Dutch general practitioners; and
2. to examine the current referral patterns in a group of Dutch general practitioners and the factors that influence the decision to refer.

Materials and methods.
A questionnaire, containing 22 sections, was designed to investigate the need for endodontic referral as perceived by the dentist, the factors that influenced the decision to refer a patient, the specialist to whom a patient was referred and the frequency of referring. A short explanation was supplied in order to clarify the purpose of the study.
These questionnaires were distributed in two stages. One part of the sample consisted of 500 dentists practising in different areas of the Netherlands and attending a scientific meeting of the Netherlands Society for Endodontology (NVvE) in November 2000.The questionnaire was distributed to the participants prior to the start of the scientific programme. Completed questionnaires were collected anonymously on the same day in special boxes placed in the congress hall. No attempt was made to collect the questionnaires by mail after the meeting took place.
The second part of the sample was collected by advertising in a newsletter provided by the Dutch Dental Association (NMT) to members of so-called ‘alpha study groups’. These study groups have been founded by the NMT in order to enhance quality by a process of intercollegiate consultation and testing. The dentists of these study groups were asked to respond prior to a lecture that covered the question of when to refer a complex endodontic case. In total 20 out of152 study groups responded to the request in the newsletter, from which 10 study groups (consisting of 83 general dentists) could participate in the study. The questionnaires were mailed to the contact persons of the different study groups, who then distributed the forms. The dentists were asked to fill out the questionnaire and to return the form on the evening of the meeting just before the lecture took place. For participants in the study, membership of the NVvE and year, school and place of graduation was recorded.

Data analysis.
Completed questionnaires were coded and entered in a database prior to analysis, which was performed using frequencies and mean values where appropriate. The two groups of the sample were compared using chisquare tests to exclude differences between the members of the alpha study groups and the participants of the scientific meeting of the NVvE. Members and nonmembers of the NVvE and the time since qualification (dentists who graduated >20 years, between10 and 20 years and <10 years ago) were compared using chi-square analysis.