DMFR 25R_02 Dentomaxillofacial Radiology (2002) 00,, 000 ± 000 ã 2002 Nature Publishing Group. All rights reserved 0250 ± 832X/02 $25.00
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Radiographic practices of dentists undertaking endodontics in New Zealand 1
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NP Chandler*,1 and S Koshy1
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School of Dentistry, University of Otago, Dunedin, New Zealand
Objectives: To determine the radiographic practices of New Zealand dentists undertaking root canal treatment, and to investigate the relationship between radiographic practices and educational and clinical factors. Methods: A questionnaire was sent to all 1200 general dental practitioners and ®ve specialist endodontists in New Zealand. Data were subjected to descriptive and analytical statistics. Results: The response rate was 79%. The mean number of root canal treatments done by general dentists in the previous 12 months was 103, and for the specialists 938. Pre-operative views were taken by 57.1% of respondents all the time and by 34.8% in most cases. The long cone paralleling and bisecting angle techniques were in regular use by similar numbers of respondents, and over one half of the practitioners regularly used ®lm holders and electronic apex locators. Working length ®lms were taken by 67% of practitioners all the time and by 18% in most cases. One-quarter of practitioners took a master point view all the time, and 15% did this for most cases. Almost 65% always took a ®lm of the completed root ®lling and 21% did for most cases. Twenty-three per cent of practitioners did not follow up their work. Conclusions: The majority of respondents used radiographs pre-operatively, for working length assessment and to assess the ®nal root ®lling. There was a general improvement in radiographic practices compared with data from a previous national survey held in 1980. Dentomaxillofacial Radiology (2002) 00, 000 ± 000. doi:10.1038/sj.dmfr.4600717 Keywords: radiography, dental; quality of health care; endodontics
Introduction
Materials and methods
Radiography is a very important diagnostic tool in endodontics and one of the key indicators of success. In a study in New Zealand in 1980, 95% of general dental practitioners (GDPs) surveyed used a preoperative radiograph and 83% considered it necessary to obtain a working length radiograph. Ten per cent did not take a radiograph on completion of treatment.1 The goals of this study were: (1) to determine the current status of endodontic radiography by GDPs and endodontic specialists in New Zealand; (2) to compare current practices to a study completed in 1980 and (3) to investigate the relationships between radiography and factors such as education and clinical practice.
The sample included all 1200 GDPs registered with the Dental Council of New Zealand and resident in the country on June 30th 20002 and ®ve specialist endodontists in full-time private practice in the country. A questionnaire was developed and pretested by three general dentists, an endodontist and a senior dental academic for ambiguity, content validity, reliability and clarity. Some questions in the survey were used to test alternate-form and intrarater reliability. The mailing and collection of questionnaires were contracted out to a professional ®rm. A reminder letter followed the questionnaire after 2 weeks, with remailing of the questionnaire targeted at non-respondents after 1 month. The returned questionnaires were coded, and data entered and veri®ed by double entry. Data were analysed using the Statistical Package for Social Sciences (SPSS, Chicago, IL, USA). Descriptive and analytical statistics were used to examine the distribution of the responses. The
*Correspondence to: N Chandler, Department of Oral Rehabilitation, School of Dentistry, University of Otago, PO Box 647, Dunedin, New Zealand; E-mail:
[email protected] Received 19 March 2002; revised 12 June 2002; accepted 21 June 2002
Endodontic radiography NP Chandler and S Koshy
association between the variables was examined by cross tabulations, and their signi®cance determined by w2 analysis. Categories used in the questionnaire were `all the time', in `most cases', `usually', `almost never' and `not at all'. A question on level of interest in endodontics also had a ®ve-point scale, from `not interested at all' to `top priority as an interest'. Practitioners were classi®ed into three groups, those that had been quali®ed less than 10 years (young), between 10 and 20 years and over 20 years (old).
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The results are summarised in the Tables. Of the questionnaires sent to GDPs, 15 were returned for reasons including deceased, overseas, left the country permanently, no longer in practice, or not known at the address. Therefore, the ®nal ®gure was 1185. In total, 931 valid questionnaires were returned and the response rate of the valid sample was 79%. Responses were received from all ®ve specialists. The mean number of root canal treatments done by the GDPs in the previous 12 months was 103, and for the specialists 938. The majority of respondents (91.8%) stated that they were very interested or moderately interested in endodontics; only 0.7% were not interested at all in the subject. Slightly more GDPs used the long cone paralleling technique than the bisecting angle method all the time (26.3% and 22.4% respectively). Film holders were used all the time by 26% of respondents. Over half of the respondents took a pre-operative ®lm all the time, but neither this nor the number of ®lms taken were considered signi®cant to the respondents opinion on treatment outcome (P=0.279 and P=0.491 respectively). More than 84% of the dentists took a working length ®lm either all the time or in most cases, and this was signi®cantly related to treatment outcome (P=0.043). Electronic apex locators were popular, and led to a signi®cant reduction in the number of radiographs taken. Very few practitioners did not take a ®nal radiograph (0.7%), and 14% followed up their patients for 4 years or longer. Over 5% were using digital imaging all the time for endodontics. Those dentists using rubber dam were found to employ radiographic and other techniques recommended in published guidelines.
should include . . . the preoperative, appropriate working, postoperative and follow-up radiographs or digital radiographic images.3 Pre-operative radiograph A pre-operative radiograph was taken all the time by 57.1% of practitioners and all the time by all the specialists (Tables 1 and 2). Only one GDP (0.1%) claimed to never take a pre-operative ®lm, this being a great improvement on the survey of 1980 when 5% did not take such a view.1 Radiographic technique Slightly more GDPs were found to use the long cone paralleling technique all the time compared with the bisecting angle (Table 3). The New Zealand specialists used the paralleling technique all the time or in most cases (Table 4). The bisecting angle method is not the best practice since image distortion can occur.4 It has also been reported that the paralleling technique provides the most reliable information about the extent of a pathological process.5 Among the GDPs the long cone paralleling method was used signi®cantly more by recent graduates (P=0.0005). This method has been taught in New Zealand for over 20 years. Table 1 Radiographs taken during root canal treatment by 931 GDPs. Values are percentages Radiographs Pre-operative Working length Master files in place Master cones in place Final radiographs
All the In most Almost time cases Usually never 57.1 66.7 14.4 24.6 64.5
34.8 17.7 11 15.1 21
7.8 11.1 29.7 28.3 11.4
0.2 3.4 29.3 21.8 2.4
Not at all 0.1 1.1 15.6 10.2 0.7
Table 2 Radiographs taken during root canal treatment by five specialist endodontists. Values are percentages Radiographs Pre-operative Working length Master files in place Master cones in place Final radiographs
All the In most Almost time cases Usually never 100 80 0 20 80
0 0 20 0 20
0 20 40 40 0
0 0 20 40 0
Not at all 0 0 20 0 0
Discussion The response rate for this survey was better than that of the national survey of endodontics held in 1980, which had a response rate of 55%.1 Surveying all the GDPs in the country with such a high response rate reduces the possibility of non-respondent bias. There is no `gold standard' as such for endodontic radiography, although some speci®c recommendations appear in textbooks and journals. The American Association of Endodontists states `Treatment records Dentomaxillofacial Radiology
Table 3 Radiographic techniques used for endodontics by 931 GDPs. Values are percentages Technique Long cone paralleling Bisecting angle Film holder Digital imaging Patient's finger
All the In most Almost time cases Usually never 26.3 22.4 26 5.6 17.4
23.5 26.6 21.3 0.9 26.6
20.2 26.7 20.5 1.1 25.3
8.4 8.1 8.7 2.5 11.2
Not at all 21.7 16.3 23.6 89.8 19.4
Endodontic radiography NP Chandler and S Koshy
Table 4 Radiographic techniques used for endodontics by five specialist endodontics. Values are percentages
0 20 0 0 ±
0 20 0 20 ±
Not at all 0 40 0 80 60
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Long cone paralleling Bisecting angle Film holder Digital imaging Patient's finger
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All the In most Almost time cases Usually never
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Film holders It is well established that use of ®lm holders in endodontics assists in producing accurate and consistent images. The American Dental Association recommend the use of ®lm holders to prevent irradiation of ®ngers and damage to ®lms by bending.6 In our study the specialists used a ®lm holder either all the time or in most cases, and never used the patient's ®nger. Among the GDPs the use of the patient's ®nger was a feature of older practitioners (P=0.015), but the use of a ®lm holder was not related to year of quali®cation (P=0.253). In Scotland in 1999 ®lm holders were used by fewer GDPs all the time (21.6%), and it was found that ®lm holders were used more frequently by those who had quali®ed after 1983.7 Assessment of working length and electronic apex location In the 1980 study of endodontics in New Zealand only 83% considered it necessary to take a radiograph of an instrument in a tooth in order to establish working length.1 In 2000, 66.7% took this view all the time and only 1.1% did not take this view at all (Table 1). In a study of graduates of the Cardi (Wales) dental school, 89% took this view, with those aged less than 29 taking the view 94% of the time and those in the 40 ± 60 year age group taking it 86% of the time.8 In some studies a small number of dentists relied on tactile sensation.8 This has been shown to be unreliable because the apical constriction may be modi®ed by resorption. Most dentists take one or two radiographs to estimate working length. However, electronic apex locators (EAL) have gained in popularity since they now allow measurements in the presence of irrigating solutions. In vitro experimental models suggest these machines are useful and accurate,9 with some researchers indicating greater reliability than radiographs in the determination of root length.10,11 In our survey 27.5% of GDPs used an EAL all the time, 14.4% in most cases and 11.5% usually. A very signi®cant reduction in the number of radiographs taken during the treatment of a maxillary molar was also noted among the users of an EAL (P=0.0005); this should have signi®cant bene®t to the patient in minimising radiation exposure. Use of an EAL was also related to the year of quali®cation of the practitioner (P=0.0005), with EAL use favoured by younger practitioners. Surprisingly none of the
specialists used an EAL all the time and two of the ®ve never did so. In a 1994 study of 1000 GDPs and 500 endodontists in the USA only 10% used an EAL.12 In a recent Scottish study 7.7% used an EAL most of the time but over 80% did not use one at all.7 In Japan more than 90% use an EAL to determine working length and 77% take radiographs.13 This very high usage of EAL may represent 60 years of Japanese development, manufacturing and marketing of four generations of these devices. It is notable, however, that in Japan large numbers of radiographs are also exposed. The EAL has particular merit in the treatment of maxillary posterior teeth, where the position of the apex may be dicult to interpret due to the zygomatic process or an undistorted image dicult to achieve.14
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Trial point radiograph In a study on litigation in endodontics Cohen15 comments on the importance of radiographs as part of the treatment record, with trial (master) point radiographs prior to cementation considered optional. This view was taken by 32% of GDPs in the 1980 NZ survey1 and by 24.6% all the time and by 15.1% in most cases in 2000 (Table 1). In Scotland in 1999 it was taken all the time by only 10.5% of practitioners.7 In our study there was a signi®cant relationship between the taking of this view and year of graduation (P=0.042), with older dentists taking the view more frequently. This may represent greater con®dence in length assessment among younger dentists using an EAL. In a recent survey less than a quarter of the graduates of the Welsh dental school took this view, with 50% rarely or never taking it.8 In that study there was no relationship between the age of the practitioner or the number of root canal treatments done and the taking of this view. Final radiograph The New Zealand specialists invariably took a ®nal radiograph. Some 60.4% of the GDPs always took this view, but it was almost never taken by 2.4% of practitioners, and never taken by 0.7%. This is an improvement from the 1980 New Zealand study, which reported that 10% never took a ®nal radiograph.1 Final radiographs were taken all the time at higher frequency in the Scottish study.7 This might be because the GDPs in that survey worked to National Health Service (NHS) contracts, where although ®nal radiographs of ®lled canals are not mandatory, the regulations state that `appropriate radiographs should be available'. In the Welsh study more than 75% took a ®nal radiograph routinely.8 Of the 6% that `rarely or never did', all of them were in the 40 ± 46 year age group. In the present New Zealand study, the more recently graduated GDPs took a ®nal radiograph more frequently (P=0.009). Dentomaxillofacial Radiology
Endodontic radiography NP Chandler and S Koshy
Radiographic technique and use of a rubber dam Periapical radiographs are more dicult to take with a rubber dam and particularly a dam clamp in place. Table 5 relates radiographic techniques to the use of the rubber dam, which is considered the standard of care in endodontics.16 There was little dierence in the use of rubber dam between those who used a long cone paralleling technique routinely (all the time, in most cases or usually) and those who used the bisecting angle technique. Practitioners using a ®lm holder routinely and following up their patients radiographically after 4 years tended also to be rubber dam users. We have previously shown that those who use rubber dam are more likely to use instruments, irrigants and radiographic techniques recommended in guidelines.17
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Follow up Periapical disease without signi®cant symptoms may be present in teeth before as well as after root canal treatment, so radiographs are necessary to monitor healing.18 The recommended review period to evaluate endodontic success is 4 years or more.19,20 Over 76% of current New Zealand (NZ) GDPs followed up their patients, an encouraging improvement on the 43% doing so in 1980.1 Only 55% of recently surveyed Scottish dentists followed up their work.21 In the present study, 13.2% followed up their patients for 4 years or longer whereas in 1980 no NZ dentists were recalling them for longer than 2 years.1 In the recent Scottish survey only 4.4% of GDPs were following up for 4 or more years.21 All the New Zealand specialists followed up their patients over periods ranging from 6 months to 2 years. In a study in the USA endodontists were more likely to carry out a 6 month recall than the GDPs, but the recall rates were similar at 1 year. Very few carried out recalls at longer intervals, with signi®cantly more GDPs indicating that recalls were not done.12 Digital radiographs An increasing use of digital imaging in general practice is expected as computers move from the reception area and into the dental surgery. Advantages include less Table 5 Relationship between endodontic radiographic techniques and practices and rubber dam use by 931 GDPs
Techniques, practices Long cone paralleling Bisecting angle Patient's finger Film holder Digital imaging Working length Final radiograph Dentomaxillofacial Radiology
Use rubber Do not Numbers dam use rubber stating routinely dam routinely they are (%) (%) using 57 54 52 70 59 57 58
43 46 48 30 41 43 42
503 550 510 486 49 814 833
P =0.137 50.0005 50.0005 50.0005 =0.879 =0.182 =0.557
radiation to the patient, a reduction in time between exposure and image interpretation, the ability to manipulate the image following acquisition, and electronic storage of patient records. In 2000, 5.6% of New Zealand GDPs were using digital imaging all the time for endodontic radiography with 89.8% responding that they did not use this at all. This suggests a much greater uptake of this technology than the 1999 survey of Scottish dentists, where only 1.6% of respondents used digital imaging all the time.7 In our survey there was a signi®cant relationship between the use of digital imaging and young practitioners (P=0.036). There was a lack of interest among the specialists (Table 4), possibly as digital radiographs do not appear to be superior to conventional images for clarity of ®les in canals or for the determination of apical radiolucencies.22 Total number of radiographs taken In the present study 43.3% of respondents took three radiographs during the endodontic treatment of a maxillary molar and 24.6% took four views. In the Scottish study7 56.7% took three views and 16.7% took four. In both surveys only about 1% of GDPs took just one ®lm. All the Scottish participants were working for the publicly funded NHS. In an earlier study by Pitt Ford et al.23 it was found that more radiographs were made by dentists working privately. In that study over 40% of NHS practitioners took two radiographs, while over 40% of private contractors took three views. In the present study all the specialists reported taking four views during the treatment of a maxillary molar. Level of interest in endodontics was not related signi®cantly to the number of views taken (P=0.121); there was also no relationship between ®lms taken and attendance at a course on endodontics in the past 3 years (P=0.057). Signi®cantly more radiographs were taken by rubber dam users (P=0.014). As expected, more radiographs were exposed by those following up their patients (P=0.009). There was also a signi®cant relationship between the number of radiographs taken and year of quali®cation (P=0.001), with the younger dentists taking more ®lms. Place of graduation New Zealand with a population of 3.7 million has only one School of Dentistry and a signi®cant number of overseas trained GDPs. We found no dierences between the two groups in their level of interest in endodontics (P=0.805). There was also no signi®cant dierence in the number of radiographs they took during root canal treatments (P=0.24). In conclusion, while this study has shown a welcome improvement in standards of endodontic radiography in New Zealand since 1980, it has also revealed areas where further improvements are possible.
Endodontic radiography NP Chandler and S Koshy
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1. Tidmarsh BG. New Zealand Endodontic Survey. NZ Society of Endodontics Newsletter 1980; 13: 10 ± 13. 2. Dental Council of New Zealand Website: www.dentalcouncil.org.nz. (2000). 3. American Association of Endodontists. Appropriateness of care and quality assurance guidelines. 3rd edn. Chicago: American Association of Endodontists, 1998. 4. Forsberg J. Radiographic reproduction of endodontic `working length': Comparing the paralleling and bisecting-angle techniques. Oral Surg Oral Med Oral Pathol 1987; 64: 353 ± 360. 5. Forsberg J, Halse A. Radiographic simulation of a periapical lesion comparing the paralleling and the bisecting-angle techniques. Int Endod J 1994; 27: 133 ± 138. 6. ADA Council on Scienti®c Aairs. An update on radiographic practices: information and recommendations. J Amer Dent Assoc 2001; 132: 234 ± 238. 7. Saunders WP, Chestnut IG, Saunders EM. Factors in¯uencing the diagnosis and management of teeth with pulpal and periradicular disease by general dental practitioners. Part 2 Br Dent J 1999; 187: 548 ± 554. 8. Jenkins SM, Hayes SJ, Dummer PMH. A study of endodontic treatment carried out in dental practice within the UK. Int Endod J 2001; 34: 16 ± 22. 9. Jenkins JA, Walker WA, Schindler WG, Flores CM. An in vitro evaluation of the accuracy of the Root ZX in the presence of various irrigants. J Endod 2001; 27: 209 ± 211. 10. Pratten DH, McDonald NJ. Comparison of radiographic and electronic working lengths. J Endod 1996; 22: 173 ± 176. 11. Kaufman AY, Keila S, Yoshpe M. Accuracy of a new apex locater: an in vitro study. Int Endod J 2002; 35: 186 ± 192. 12. Whitten BH, Gardiner DL, Jeansonne BG, Lemon RR. Current trends in endodontic treatment: report of a national survey. J Amer Dent Assoc 1996; 127: 1333 ± 1341. 13. Yoshikawa G, Sawada N, Wettasinghe KA, Suda H. Survey of endodontic treatment in Japan. J Endod 2001; 27: 236.
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for her collaboration throughout the project. Statistical guidance was provided by Dr Paul Pillai of the School of Business, University of Otago. The New Zealand Society of Endodontics, Dentsply and 3M Dental supported the study. The Dental Council of New Zealand provided their database of practitioners.
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Acknowledgements The authors thank the GDPs of New Zealand for their excellent response and Professor WP Saunders (Dundee, Scotland) for kindly providing the questionnaire used as a prototype for our survey instrument. Dr Nancy Devlin, Fellow (Health Systems) King's Fund, London is thanked
14. Chandler NP, Anderson NR. Molar root canal treatment without working length radiographs: case report. N Z Endod J 1998; 24: 10 ± 12. 15. Cohen S. Endodontics and litigation: an American perspective. Int Dent J 1989; 39: 13 ± 16. 16. European Society of Endodontology. Consensus report of the European Society of Endodontology on quality guidelines for endodontic treatment. Int Endod J 1994; 27: 115 ± 124. 17. Koshy S, Chandler NP. Use of rubber dam and its association with other endodontic procedures in New Zealand. N Z Dent J 2002; 98: 12 ± 16. 18. Lin LM, Pascon EA, Skribner J, Gangler P, Langeland K. Clinical, radiographic, and histologic study of endodontic treatment failures. Oral Surg Oral Med Oral Pathol 1991; 11: 603 ± 611. 19. érstavik D. Time-course and risk analyses of the development and healing of chronic apical periodontitis in man. Int Endod J 1996; 29: 150 ± 155. 20. Strindberg LZ. The dependence of the results of pulp therapy on certain factors. An analytic study based on radiographic and clinical follow-up examinations. Acta Ondontol Scand 1956; 14 (suppl 21): 1 ± 175. 21. Saunders WP, Chestnut IG, Saunders EM. Factors in¯uencing the diagnosis and management of teeth with pulpal and periradicular disease by general dental practitioners. Part 1 Br Dent J 1999; 187: 492 ± 497. 22. Friedlander LT, Love RM, Chandler NP. A comparison of phosphor-plate digital images with conventional radiographs for the perceived clarity of ®ne endodontic ®les and periapical lesions. Oral Surg Oral Med Oral Pathol 2002; 93: 321 ± 327. 23. Pitt Ford TR, Stock CJR, Loxley HC, Watson RMG. A survey of endodontics in general practice in England. Br Dent J 1983; 154: 222 ± 224.
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