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A number of studies have shown that the standard of root canal treatment performed by general dental practitioners is less than satisfactory.1,2,3,4,5,6,7 Although the success rate of root canal treatment has been shown to be high, a number of recent studies from various countries have shown a high frequency of poorly executed root canal treatments with periradicular disease going apparently undetected and untreated.4,5,6,7 It is postulated that this may be because of a number of reasons including the difficulty of the technical procedures, lack of understanding of the principles and aims of treatment, poor remuneration for the time required and inadequate teaching at undergraduate level. In a review of endodontics in the UK in 1990, Stock8 stated that at a workshop in endodontics in 1978 the standard of endodontic treatment had been regarded as less than satisfactory. Despite establishing guidelines and increasing awareness of remuneration for endodontics in the NHS, he asserted that the standard had not improved over the 12-year period. This is further complicated by the shift in the delivery of endodontic care from teeth with relatively easily accessible root canal systems in younger patients, to teeth with previous extensive restorations in older patients. The root canal systems in the latter tend to be much more difficult to find and negotiate. In addition, patients are now more anxious to retain their teeth and thus root canal treatment is preferred to extraction.

A study of the reasons for referral for surgical root canal treatment showed that the majority of cases did not fulfil the guideline criteria for surgery, thus demonstrating a lack of knowledge in the principles of root canal treatment failure.9

There have been no previous studies on the attitudes of general dental practitioners to root canal treatment. Therefore, the aims of this study were as follows:

  • Analyse the provision of non-surgical and surgical root canal treatment in adults in Scotland

  • Establish whether there are variations in treatment provision in different regions in Scotland

  • Examine the confidence of general dental practitioners in their ability to diagnose and treat periradicular disease

  • Investigate the factors that influence the management by general dental practitioners of periradicular disease

  • Examine the referral patterns of general dental practitioners to colleagues for root canal treatment.

Methods

The investigation was conducted in two stages.

Stage 1 Analysis of returns to the Scottish Dental Practice Board

Data provided by the Dental Practice Division were analysed to provide information on the distribution of endodontic treatment carried out in Scotland, as well as numbers of non-surgical and surgical root canal treatments carried out during one year.

Stage 2 Questionnaire

This aspect of the investigation was conducted using a self-administered postal questionnaire.

The participants

The study sample consisted of 617 general dental practitioners, which is 33% of those practising under the GDS in Scotland. Names were selected at random from a database supplied by the Scottish Dental Practice Board, Edinburgh. This represented all the regions of Scotland.

The questionnaire

The questionnaire contained 37 items and a combination of open and closed questions were posed. Respondents were identified only by codes and attitudinal variables were measured using five-point Likert scales. The questionnaire was pre-tested and validated on a random sample of 40 dentists practising in Scotland. Improvements in clarity and simple errors were corrected after analysis of the pilot study.

Data collection

The main mailing was carried out in mid-July 1998 together with an explanatory letter and a prepaid envelope. Non-respondents were sent a further questionnaire four weeks later.

Data analysis

Completed questionnaires were coded and entered into a database prior to analysis by SPSS (Chicago, IL, USA). Frequencies were used to examine the distribution of responses for all variables and describe sample demographics. The association between variables was examined by cross-tabulations and the statistical significance of such relationships determined by Chi-square analysis

Results

Stage 1 Analysis of returns to the Scottish Dental Practice Board

In the period, year ending March 1997, a total of 106,004 non-surgical root canal treatments were carried out on patients aged 18 years and over. Of these, 40,379 were in incisors and canines, 23,575 in maxillary premolars, 15,849 in mandibular premolars and 26,201 in molars. Some 8,841 non-surgical root canal treatments were carried out on patients under the age of 18 years. The distribution was 3,697 incisors, 1,524 maxillary premolars, 776 mandibular premolars and 2,844 molars. Surgical root canal treatment, termed apicectomy by the Dental Practice Division, was undertaken in 1,742 incisors and canines, 254 premolars, 39 buccal roots of maxillary molars and 7 other roots in patients over 18. Of these 1,356 also had a root-end filling placed. In patients under 18 years of age, 49 apicectomies were carried out on incisors or canines, two on premolars and only one on the buccal roots of a maxillary molar. A root-end filling was placed in 31 cases. A small number of retained deciduous teeth were also treated, 10 in the over 18 year age group and 17 in the under 18s.

The distribution of treatments throughout Scotland for 1997/98 is shown in Table 1. Not surprisingly, the areas of greatest population, especially the 'central belt' produced the greatest number of cases. The number of treatments per 1000 population aged 18 years and over varied between 18.1, in Shetland, to 52.3 in Greater Glasgow.

Table 1 Table 1
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Stage 2 Analysis of the Questionnaire

The response and the respondents

Of the 604 questionnaires mailed 417 (69%) were returned. In 4 cases the questionnaires had not been completed because the respondents were in full-time orthodontic practice and thus the questions posed were irrelevant. The time since graduation covered 41 years with a mean of 16.2 years and a mode of 15 years. With regard to the sphere of practice, the majority of respondents 215 (51.6%) reported their practice as mixed NHS and independent, 173 (41.5%) worked exclusively in the National Health Service and 17 (4.1%) were mainly independent practitioners.

Diagnosis and treatment of periradicular disease

The majority of respondents (382/94.1%) undertook root canal treatment whilst only 24 (5.9%) did not carry out this type of treatment. Of these, 4 were in practice limited to orthodontics. When asked about confidence in their ability to diagnose periradicular and dental pulp disease the majority of respondents (360/89.3%) felt either extremely confident or confident, 41 (10.2%) were neutral and 2 (0.5%) were not very confident. When related to the time qualified there was no statistically significant differences in relation to confidence of diagnosing disease and time since qualification.

The majority of respondents (303/77.1%) were either extremely confident or confident in their ability to treat periradicular and dental pulp disease. Eighty four (21.4%) of respondents were neutral and only 6 (1.5%) were not very confident of their ability. None of the respondents felt that they were not at all confident of their ability to diagnose and treat periradicular and dental pulp disease.

Referral for treatment

The majority of respondents (268/70.2%) undertook all the root canal treatment themselves with the remainder referring to a non-specialist colleague (9/7.3%), a specialist in practice (25/20.2%) or to a specialist in a hospital (90/72.6%). The frequency with which cases were referred varied but the majority (77/52.7%) referred less frequently than once every six months. Four respondents (2.7%) referred more than once a month, 9 (6.2%) once a month, 23 (15.8%) once every 1 to 3 months and 33 (22.6%), once every 6 months.

Root canal treatment performed

The number of root canal treatments undertaken each year by the respondents varied between 5 (n=1) and 1500 (n=2) with a mean of 151 and a mode of 100. Numbers treated were considered to have increased in the last five years by 234 of respondents (63.1%).

Factors influencing decision to refer

Table 2 indicates the frequency with which respondents felt certain factors influenced their decision to refer. The time since qualification had no statistically significant effect on the attitude of the respondents to the importance of these factors.

Table 2 Table 2
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Causes of failure of root canal treatment

When asked what was considered to be the most important cause of failure of root canal treatment there were 381 replies. Of these, 114 (29.9%) were related to preparation of the root canal. These included failure to clean the root canals, failure to instrument to the full length of the root canal and failure to remove organic debris. Ninety (23.6%) respondents iterated cleaning of the root canal system. Problems associated with infection were cited by 34 (8.9%) respondents. The importance of obturation of the root canals accounted for 71 (18.6%) responses whilst 38 (10%) considered factors associated with the coronal restoration to be most important. Insufficient time to undertake proper treatment was intimated by 11 (0.3%) and 10 (0.3%) respondents considered patient factors to be the most important cause of failure. Three (0.1%) respondents did not know the reason why root canal treatments fail and 13 (0.3%) considered the lack of an apical seal was critical.

Root canal treatment related to crown preparation

Tables 3 and 4 shows the distribution of responses to a question concerning root canal treatment in relation to the hypotheses that irreversible damage to the dental pulp would occur in 10% and 50% of crown preparations. Those more recently qualified practitioners were statistically significantly less likely to undertake elective root canal treatment if the chances of pulp death was 10% or 50% (P<0.01 and P<0.01, respectively). When the results obtained for the 10% and 50% pulp death groups were compared there was a statistically significant correlation between the two with more practitioners advocating elective root canal treatment if 50% of pulps became non-vital after crown preparation (P<0.001).

Table 3 Table 3
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Table 4 Table 4
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Questions were also asked relating to the root canal treatment of teeth with existing crowns. Five (1.3%) of respondents most definitely would remove the crown in a posterior tooth prior to root canal treatment, and 46 (11.6%) would remove the crown in most cases. The majority (182/46.1%) occasionally removed the crown and 150 (38%) almost never removed the restoration. Only 12 (3.0%) would definitely not remove the crown. Most of the respondents (262/ 67.5%) stated that they would cut an access cavity in the crown in most cases; 47 (12.1%) would definitely cut an access through the crown and 71 (18.3%) would occasionally cut an access cavity through the crown. A very small minority almost never (6/1.5%) or would definitely never undertake this treatment (2/0.5%). The frequency of responses for factors judged to influence the decision to remove or retain a crown on a molar tooth prior to root canal treatment are shown in Table 5. Written comments (n=85) expressed a certain dilemma about whether a crown should be removed. The cost to the patient of a replacement was a significant disincentive to removal (23/27%) as were the patient's wishes (9/10.5%). Fifteen respondents (17.6%) would only remove the crown if it was relatively easy to dislodge, two respondents felt rubber dam was easier to place with the crown in place and four considered that isolation of the root canal system was easier. Two others felt that lack of time precluded dismantling.

Table 5 Table 5
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Aspects considered to be most difficult in root canal treatment of a molar were ranked from the most difficult (1) to the easiest (6). The results are shown in Table 6. Finding the root canal was judged to be the most difficult by the majority of respondents and isolation of the root canal system the easiest. Significantly more of the less recently qualified practitioners regarded access to the root canal as one the most difficult aspects (P=0.019). This group also considered finding the root canals and preparing the root canal system more difficult than the practitioners who qualified after 1983 (P=0.002 and P=0.028,respectively)

Table 6 Table 6
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Follow up

One hundred and seventy two (44.2%) respondents did not follow up their root canal treatments radiographically. The distribution of the remainder was: six months, 61 (15.7%); one year, 78 (20.1%); 18 months, 14 (3.6%); two years, 34 (8.7%); three years, 12 (3.1%); four years, 5 (1.3%); more than 4 years, 13 (3.3%).

Surgical root canal treatment

Two hundred and twenty (52.8%) dentists undertook surgical root canal treatment. This included apicectomy (215/57.3%), repair of perforation (92/22.1%), periradicular curettage (78/18.7%) and root resection or hemisection (72/17.3%). The number of practitioners undertaking surgery for each tooth type is shown in Table 7.

Table 7 Table 7
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Success of root canal treatment

The importance of various factors in the success of root canal treatment was ascertained. These are shown in Table 8. Analysis of the data showed that a statistically significantly greater number of recently qualified dentists thought that the subsequent coronal restoration was important for successful root canal treatment (P=0.008). There were no other significant cross tabulations with the time since qualification.

Table 8 Table 8
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Disincentives to performing root canal treatment in multirooted teeth.

Three hundred and fourteen of the respondents considered that there were disincentives to undertaking root canal treatment. The factors that they were asked to consider are annotated in Table 9. Under the 'Others' section, most of the written comments were concerned with the poor remuneration for root canal treatment under the health service and the patient's lack of interest in paying a 'reasonable rate for the work'. Other comments included 'unless well motivated, tolerant, private patient then the stresses on patient, nurses and dentist can be intolerable and soul destroying; as in many other dental disciplines if try to apply as taught, in the treadmill of NHS dentistry': 'remuneration is the main problem as far as molars are concerned — anything complicated stops it worth doing financially': 'feel pressure is often to do molar endo in <1 hour — this I cannot do!!': 'poorly remunerated for the complexity of the task and time required to do a decent job': 'not appreciated by the patient at all'.

Table 9 Table 9
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Discussion

The distribution of root canal treatment as evidenced by the number of treatments per 1000 population shows that the regions with the greatest population density had more treatments carried out. The reason for this is difficult to elucidate but there may be a number of explanations. It may be that an urban population is more anxious to retain their teeth. Registration rates at dental practices for a rural population are lower than in urban areas indicating that the urban group may consider dentistry more important. Social and economic factors in a rural community may mean that attendance at multiple appointments for root canal treatment may be difficult and patients from these areas may opt for extraction for convenience. Finally, the pathway for referral of patients for root canal treatment may be more difficult in isolated rural regions. There is a need for further research to establish differences in attitude to dental treatment between urban and rural residents.

The results of the present study indicate that a large majority of general dental practitioners claimed confidence in their ability to diagnose periradicular infection. This may reflect, in part, previous undergraduate teaching where there is a long tradition in developing diagnostic skills in pathology. A high percentage of respondents were also confident in their ability to treat periradicular disease. This is in contrast to the findings of a recent study6 which showed that the technical standard of root canal treatment in a Scottish sub-population was not high, with 58.1% of root filled teeth showing evidence of a periradicular radiolucency. This confidence may be based on a false sense of security developed because many patients have few long-term acute symptoms and only a small minority of practitioners participating in the study followed up their cases for long periods. It has been recognised that observation periods of 3–4 years may be required to record a stable treatment outcome.10,11,12,13 The number of treatments carried out by the respondents varied greatly and presumably is linked to patient demand and interest in the speciality by the dentist. A minority of respondents referred patients for root canal treatment to colleagues of which the most popular was a specialist in hospital. The introduction of specialist lists in endodontics should allow more flexibility in referral arrangements, particularly in urban areas. The long distances some patients are required to travel and the length of some referral waiting lists are at present a significant problem in many areas. Evidence from two of the undergraduate teaching dental hospitals in Scotland indicate that the greatest number of referrals to Departments of Conservative Dentistry is for root canal treatment and referral to a specialist practitioner will help to alleviate the pressure on the hospital service. Inevitably, more difficult cases are referred including perforations, retreatments and surgery. Seventy six per cent of respondents considered retreatment to be an important factor in making a decision to refer. This may be because retreatment is more difficult to undertake, is more time consuming and treatment outcome is less successful than cases treated de novo.10,14,15,16 It was clear from the results that treatment of multirooted teeth was also a factor influencing referral, cited by 44.3% of respondents as being very important or important. This may be related in part to difficulties in locating root canals (cited as being the most difficult problem) and poor remuneration for the treatment time required.

There are many factors that influence success and failure in root canal treatment and these have been reviewed by Friedman.17 Thirty percent of respondents considered failure to be linked to preparation of the root canal. It is generally accepted that infection within the root canal system is the most important cause of failure of root canal treatment and that during treatment, efforts should be made to render the root canal as clean as possible.10,18 This is linked to the preparation phase of treatment. Subsequent failure is associated with re-infection of the root canal mainly from coronal leakage of micro-organisms.19 Only ten percent of the respondents considered factors concerning the coronal restoration to be the most important cause of failure. Ray and Trope20 in a radiographic study of the technical quality of the root filling and the coronal restoration found that the quality of the latter was a more significant factor in success. Seventy one respondents (18.6%) considered the obturation of the root canal to be important in failure. Whilst obturation certainly provides a barrier against coronal contamination from micro-organisms and their by-products, gutta-percha root fillings do not provide a bacteria-tight seal.21,22,23 Several published studies have demonstrated healing of periradicular periodontitis after preparation of the root canal system but with no obturation.24,25 Such success would predicate on an excellent coronal seal eliminating re-infection of the root canal system from the oral cavity.

The majority of respondents to the survey regarded finding the root canals and cleaning the root canal system as major factors of importance for successful treatment. Eighty per cent considered that the position of the root filling relative to the apex was also important. It is known that the level of the root filling has a significant effect on the outcome of treatment of teeth with periradicular periodontitis. Teeth filled to within 2 mm of the radiographic apex have a higher success rate than those where the filling is short or where the root canal is overfilled.26 The subsequent coronal restoration was considered by 74% of respondents to be important for success.

Preparation of vital teeth for crowns carries a risk of irreversible damage to the pulp. This damage may cause pulp death and the development of periradicular periodontitis. Studies have shown the incidence of radiographic changes in the periradicular tissues of crowned teeth to vary between 3% to 22%.27 A study conducted in Scotland found that 19% of crowned teeth with no root filling had radiographic changes periapically.28 When asked whether elective root canal treatment would be undertaken if there was a 10% or 50% risk of irreversible pulp death during crown preparation, statistically significantly more practitioners stated that root canal treatment would be done electively if 50% of pulps became damaged. The success rate for root canal treatment without the presence of a periradicular radiolucency is higher than when a radiolucency is present17 so it would seem expedient to undertake root canal treatment if the chances of pulp damage are high. This principle of risk management in relation to treatment planning in endodontics requires further study.

Root canal treatment in teeth may be complicated if a crown is already in place as the latter may prevent adequate vision of the pulp chamber and openings of the root canals. Such information cannot be gleaned from the pre-operative radiograph in these cases because the pulp chamber is masked by the crown. Conversely, the presence of a crown allows easier isolation of the tooth and the strength of the metal restoration allows an adequately sized access cavity to be cut without fear of collapse of the coronal restoration. Few respondents remove the crown routinely prior to root canal treatment. There is a predicament that seems to be based largely on patient factors, including the expense of replacement of the crown. There was a considerable disincentive to removing the crown if it was a bridge retainer or if the fit of the crown was satisfactory. If recurrent caries was present then a large majority (86.6%) of respondents would remove the crown. A basic premise for root canal treatment is that all caries should be removed from the crown of the tooth prior to the start of treatment to avoid subsequent contamination of the root canal system by micro-organisms during and after treatment.

This study also examined aspects of root canal treatment that general dental practitioners considered most difficult. Finding and preparing the root canals was judged to be most difficult by the majority of respondents. These aspects of root canal treatment have been improved over the last few years with the introduction of the operating microscope and with much more common use of magnifying loupes which allow much better vision, and ultrasonically powered instruments for more controlled dentine removal coronally.29 Unfortunately, such items are expensive and general dental practitioners have been slow to incorporate these advances into their dental practices. The older cohort of dentists regarded these aspects as more significant than those who qualified after 1983, perhaps reflecting the change in teaching in recent years which stresses the need for magnification as an aid in root canal treatment.

Over 50% of dentists questioned undertook surgical root canal treatment and maxillary anterior teeth were most commonly treated. The low numbers of respondents who treated molar teeth probably reflects both the fee structure and the difficulty of the surgical procedure.

There were more non-surgical root canal treatments carried out on single rooted teeth than on molars. Considerable disincentives were recorded for the root canal treatment of molars, but one of the most important was the fee structure that was considered to be inadequate for the time and effort taken. Lack of patient interest was also a major disincentive and indicates the need for education on the importance of this treatment in retaining the tooth as a functional unit.

Overall, the results of this study indicate that the majority of general dental practitioners who responded to the questionnaire had knowledge of current endodontic theory. However some practitioners were unaware of the factors influencing success and failure in root canal treatment. There were considerable difficulties associated with the execution of root canal treatment, related to remuneration and patient compliance. The practice of endodontics as reported by these general dental practitioners will be described in the second paper.