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Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results
Journal of Dentistry (2004) 32, 343–350
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Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results F.J. Trevor Burke* Department of Adult Dental Care, Primary Dental Care Research Group, School of Dentistry, University of Birmingham, St Chad’s Queensway, Birmingham B4 6NN, UK Received 2 December 2003; accepted 3 February 2004
KEYWORDS Amalgam; Resin-based composite; Usage; Government; Regulations
Summary Objectives. To review governmental guidelines on amalgam use worldwide and to assess trends in the usage of amalgam and composite materials in restoration of posterior teeth. Methods. A letter was sent to 24 government health agencies or representative organisations requesting details of regulations pertaining to amalgam use. A literature search was carried out in order to identify papers in which the incidence of amalgam and composite restorations was stated. Results. Ten replies were received, indicating few restrictions on the use of amalgam. Results obtained from published work appear to indicate that amalgam use is declining, but at rates which are unclear in many countries because of the paucity of published data. Amalgam use has been found to be decreasing in the USA, Australia and Scandinavia, with lesser decreases being apparent in the UK. Conclusions. There are few restrictions to the use of amalgam worldwide. In countries where data are available, such as USA, Australia and Scandinavia, amalgam use has been found to be decreasing, with smaller decreases being apparent in the UK. q 2004 Elsevier Ltd. All rights reserved.
Introduction There is patient interest in tooth-coloured restorations in posterior teeth, both in the UK and the USA,1,2 but worldwide, it is likely that amalgam restorations are more frequently used than tooth-coloured materials. However, in a world in which so much has changed over the past century, it may be considered peculiar that dentists *Tel.: þ44-121-237-2767; fax: þ 44-121-625-8815. E-mail address: [email protected]
are placing a material in posterior teeth, which is not much changed from that used over a hundred years ago. Notwithstanding the appearance of their restorations, it is possible that patients may request tooth-coloured restorations because of worries about mercury present in dental amalgam. 3 Government agencies may also seek amalgam alternatives for environmental reasons. It is the purpose of this paper to review governmental regulations on amalgam, worldwide and to review the literature in order to determine the incidence of amalgam and composite use for
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posterior teeth in the countries where data are available.
Materials and methods Governmental regulations Names and addresses of government health agencies or representative organisations were obtained from web sites and from the British Dental Association Information Centre. A letter was sent to 24 such agencies requesting details, if they were available, of regulations pertaining to amalgam use. A second letter was sent to those who had not responded within three months.
Incidence of amalgam and composite usage A Medline literature search was carried out in order to identify papers, published since 1998, in which the incidence of amalgam and resin-based composite (RBC) restorations was stated. In addition, the author’s library of published articles was searched.
Results Governmental regulations Responses were received from 10 governmental or representative agencies in response to the first mailing of the letter requesting information, and two replies were received after the second mailing. One letter was returned. Replies, which generally were brief or provided directions to a relevant web site, were translated into English ðn ¼ 2Þ where necessary. A summary of the information received is detailed in Table 1. From the responses received, it would appear that there are few restrictions worldwide to the placement of dental amalgam. Additional information, on restrictions on the use of amalgam in Europe, is contained in the European Association of Dental Public Health (EADPH) news page in a 1998 issue of Community Dental Health.4 This stated that new advice on the use of amalgam had been sent to general dental practitioners in the UK, suggesting that it would be ‘prudent’ to avoid the use of amalgam during pregnancy. This advice was precautionary, pending further research. Dr Eva Widstrom Chief Dental Officer, National Research and Development Centre for Welfare and Health, Helsinki, Finland, provided further insight into regulations on amalgam usage in
F.J.T. Burke
an editorial in Community Dental Health in September 1997.5 The principal points addressed in this editorial included:
† Several expert groups in different countries have evaluated the scientific research on the health effects of dental amalgam. All these groups concluded that there is no direct evidence of an adverse effect of mercury from amalgam restorations on general health. † Amalgam, when properly handled, has not been shown to be hazardous to dental personnel. † Health authorities in some countries have taken a rather cautious attitude to the use of amalgam in dentistry. Major amalgam therapy has not been recommended when treating pregnant women and young children or patients with renal disease. To avoid corrosion amalgam fillings should not be placed in contact with restorations of other metals. The rationale behind these recommendations has been a desire to lower the exposure to a potentially hazardous substance during sensitive periods of life. † Amalgam separators in the wastelines of dental units are a legal requirement in some countries and there are pressures to introduce them in many more countries. † In 1995, the Commission of the European Union appointed its own expert group to clarify the reasons why some member states had restrictions on the use of, and questioned the safety of, dental amalgam. Despite the various local, regional and global research projects by different expert groups, about 250,000 dentists within the EU continue to treat their patients using amalgam filings.
Incidence of amalgam and RBC usage for restoration of loadbearing cavities in posterior teeth Data in respect of amalgam and composite usage worldwide was scarce, so the search was extended to include relevant papers published since 1995. USA Results of the ‘Question of the month’ feature in the November 1997 issue of the Journal of the American Dental Association produced a response from 355 readers, with 33% of these respondents stating that dental amalgam was not their material of choice, 65% indicating dental amalgam remained their restorative material of choice and eight respondents stating that they used amalgam about 50% of the time.6 Many of those who responded
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results
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Table 1 Representative statements on amalgam from government or representative agencies. Country and name of agency
Comments from governmental or representative agency
USA USA Food and Drug Administration
FDA and other organisations of the USPHS continue to investigate the safety of amalgam used in dental restorations. No valid scientific evidence has ever shown that amalgams cause harm to patients, except in the rare case of allergy. Since amalgam is a CE-marked product approved by a notified body in the Union, there are no regulations confining its use in Sweden. However, the Swedish Govt has abolished amalgam from the insurance reimbursement system. There is agreement between the providers of dental health (county councils) and the Ministry of Social Affairs not to use amalgam on patients below 20 years of age. The National Board of Health and Welfare recommends not to remove amalgam restorations during pregnancy. Proposed guidelines encourage dentists to minimise their use of amalgam by using an alternative whenever possible. The desire to reduce the use of amalgam is not based on a particular piece of research, but on an overall assessment of research and experience available to the dept. since 1991. No regulations: no exact data on amalgam use, but figures available on use. Of 4000 clients of a major deliverer only 50 clients order amalgam. Amalgam fillings in molar teeth permitted until further notice. There are no laws or regulations relating to the use of dental amalgam in Ireland. Amalgam is a medical device and therefore falls under the Medical Device Regulations 2002. All devices have to meet safety requirements. A way to meet this is to conform to harmonised technical standards. There are none for dental amalgam. Japan does not have any regulation prohibiting or restricting the placement of dental amalgam restorations. Due to widespread use of composite resin, amalgam has not been used much recently. ADC does not have a policy, as such, for the use of dental amalgam. Amalgam contains mercury and other metals. The produced must fulfil all the uniformly regulated fundamental requirements governed by the European Union. Currently neither the Federal Institution for Drug and MedicineProducts have justified suspicion that mercury from amalgam has a negative influence on health. In pregnant women, extensive restorative procedures should be avoided. When treating pregnant women amalgam restorations should not be placed or removed. As matters stand, there is no proof that mercury from amalgam restorations of the mother could cause any harm to the health of the unborn child. Major renal impairment represents a relative contraindication for the use of amalgam.
Sweden National Board of Health and Welfare, Stockholm
Norway Norwegian Directorate for Health and Social Welfare
Finland National Institute for Medicine, Medical Devices, Helsinki Denmark Danish Environmental Protection Agency Ireland Dental Council, Dublin United Kingdom Department of Health, London
Japan Japan Dental Association
Australia Australian Dental Council Germany Bundesministerium fur Gesundheit
‘yes’ to the use of amalgam stated that they preferred amalgam to RBC because of what they termed composite’s failures, namely, microleakage, unacceptable wear, sensitivity and lack of durability. Of the 113 respondents who stated that amalgam was not their restorative material of choice, 27 did not use amalgam at all. Data on amalgam and RBC use up to 1998 are available by way of a survey carried out by
the American Dental Association. Results from this indicated that almost half of the Class I and one third of Class II restorations placed in the USA were tooth-coloured.7 It may further be considered that a growing number of dentists are restricting their practices to the use of RBCs as opposed to amalgam in the US, where in 1995, approximately 20% of intra-coronal restorations were tooth-coloured,8 this proportion rising, by the year 1998, to 47% for
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single-surface direct-placement restorations and circa 30% for multiple surface restorations.7 Further, data on amalgam and RBC use are available from the Washington Dental Service, which has a claim-based data warehouse containing details of dental services provided to 1.5 million patients.9 Data obtained from this source indicated that the use of RBC exceeded amalgam in 1999. UK Recently published data on UK dentists’ use of amalgam and composite are available by way of a survey to 1000 dentists, for which 654 replies were received.10 Regarding choice of material, 100% of respondents cited clinical indication as the most influential factor, although patients’ aesthetic demands (99%), patients’ choice (95%) and patients’ financial situation (92%) were also reported to influence respondents’ choice. Thirty-five percent of respondents used RBC ‘sometimes’, 15% ‘often’, and 1% ‘always’ in extensive loadbearing cavities in molar teeth. Forty percent ðn ¼ 242Þ of respondents considered that secondary caries had increased as a result of decreased use of amalgam, while 46% ðn ¼ 280Þ of respondents considered that the need for root fillings had increased. Thirty-nine percent ðn ¼ 239Þ of respondents considered that loss of fillings had increased as a result of decreased amalgam use, although 47% ðn ¼ 285Þ considered that this had remained stable. For RBC restorations in posterior teeth, 92% ‘always’, ‘often’ or ‘sometimes’ used the total etch technique and 53% never used rubber dam. Seventy percent of respondents agreed with the statement ‘discontinuation of amalgam restricts a dentist’s ability to adequately treat patients’. Eighty-one percent considered that the growth in the use of composites would increase the total cost of oral health care. It was concluded that 49% of the respondents from England and Wales seldom placed large composite restorations in molar teeth and that their choice of material was influenced greatly by clinical indications and patient’s aesthetic demands. However, the use of RBC for restoration of loadbearing cavities in posterior teeth in the UK may be influenced by the fact that such restorations are not permitted under the National Health Service Regulations. Results of a cross-sectional study carried out in 1999, and using data generated by thirty general dental practitioners have indicated that one quarter of Class I restorations placed in the UK are made in RBC materials.11
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Australia Recent data are available from Australia from a couple of sources. A paper by Brennan and Spencer, which reviewed restorative treatment trends from 1983 to 1999, has provided timely data on the use of amalgam and composite in Australia.12 This work used a series of mailed surveys to a random sample of dentists in 1983 – 1984, 1988 – 1989, 1993 – 1994, and 1998 –1999, with response rates of over 70% to each. The overall number of restorative treatments declined during the study period, reflecting a steady decline in the number of amalgams placed, from a mean of 1275 per dentist in 1983 – 1984 to 437 in 1988 – 1989. However, the number of composites placed showed an increase between the 1993 –1994 and 1988 –1989 surveys, from 508 per dentist per annum to 694, respectively. The results of a survey to 1000 general practitioner dentists in Australia were presented at the International Association of Dental Research meeting in Gothenburg in June 2003.13 A total of 560 replies were received. Regarding choice of material, 99% of respondents cited clinical indication as an influencing factor, although patients’ aesthetic demands (99% of respondents), patients’ wish (96%), patients’ financial situation (82%), and lecturers’ suggestions (72%) were also reported to influence respondents’ choice of materials. Twelve percent of respondents used composite ‘always’, 29% ‘often’, 32% ‘sometimes’, 23% ‘seldom’, and 4% ‘never’ in extensive loadbearing cavities in molar teeth. Fifty-nine percent of respondents reported a decrease in amalgam use over the previous five years. Sixty-eight percent of respondents agreed with the statement ‘discontinuation of amalgam restricts a dentist’s ability to adequately treat patients’. Seventy-five percent considered that the growth in the use of composites increased the total cost of oral health care. The survey concluded that 73% of the respondents from Australia place large composite restorations in molar teeth. It is apparent from the two related surveys10,13 cited above that the use of resin composite for the restoration of posterior teeth was much more prevalent in Australia than in the UK. This difference may, however, be due, at least in part, to the guidance issued by the General Dental Services of the Department of Health in the UK, which does not allow provision of RBC restorations in loadbearing surfaces of posterior teeth, while no such restications apply in Australia.
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results Dentists in the UK and Australia were in general agreement on a number of the statements in the study questionnsire, such as: † Due to environmental reasons we should stop using amalgam (Agree: 53% UK, 48% Australia) † Pregnant dentists should not provide amalgam restorations (Agree: 60% UK, 47% Australia) † Discontinuation of amalgam would restrict dentists’ability to treat patients’ oral health (Agree: 83% UK, 75% Australia) † Growth in use of composites is increasing the total cost of oral health care (Agree: 95% UK, 89% Australia) † A low shrink composite would be a clinical advantage (Agree:98% UK, 97% Australia). Key differences between the UK and Australia included: † Reported use of amalgam decreased 9% more in Australia than in UK over past 5 years (59% cf 50%) † Reported use of composite increased more in Australia than in England over past 5 years (74% cf 62%) † Patients’ aesthetic demands influence material choice more in Australia (73% Australia cf 62% UK) † Agreement with statement ‘The use of amalgam will be discontinued by 2005’ (89% UK compared with 76% Australia). Japan A shown in Table 1, the Japan Dental Association, in 2002, stated that ‘Japan does not have any regulation prohibiting or restricting the placement of dental amalgam restorations. Due to widespread use of composite resin, amalgam has not been used much recently’. Other than this statement, there is little information on the use of RBC restorations in posterior teeth. However, results of a survey, published in 2000, into the teaching of posterior composite restorations in Japanses dental schools (response rate 93%) indicated that 93% of the respondent schools taught the use of RBC materials in Class I restorations, with most schools anticipating that the proportion of time devoted to the teching of posterior composite restortions would increase in the following five years.14 Scandinavia A paper by Ylinen and Lofroth, published in 2002, is a fruitful source of information on the use of dental amalgam in Nordic countries.15 This work used a 25-question postal questionnaire to random samples of dentists in Denmark, Finland, Norway
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and Sweden to determine attitudes to amalgam as a halth and environmental issue, and social and ethical aspects of amalgam use. The results indicated differences in amalgam usage in the four countries surveyed, with only one dentist from Finland (1%) and two (1%) from Sweden having used amalgam in a child under 12 years of age during the year preceding the survey. By contrast, 61% of the respondents from Denmark, and 33% of the respondents from Norway had used amalgam in this age group. For adult patients, the percentage using amalgam was higher in all the countries assessed, ranging from 28% in Finland, 40% in Sweden, 88% in Norway and 92% in Denmark. The dentists who had stopped using amalgam were asked when they had stopped using it, with the number not using amalgam being found to grow slowly every year. Principal alternatives to amalgam in all four countries were found to be glass ionomer for children and RBC for adults. Most respondent dentists considered amalgam to be a health risk, at least for some patients, with the percentage answering ‘no risk’ ranging from 33% in Denmark to 2% in Norway. However, the majority of dentists in all countries wanted to keep amalgam as a restorative material. A majority of the respondents considered both amalgam and RBC to be potentially harmful to patients and suggested that efforts should continue to develop better alternatives to both materials. Information on amalgam use in Europe was provided in the EADPH News Page in 1998.3 This provided information as follows: † In Finland, the use of amalgam has been reducing for some time, reflecting the improved health of the younger generation. † In 1996, approximately 7% of fillings provided by private practitioners in Finland for women aged between 20 and 40 years were amalgam. † Although there is no clear scientific evidence showing that the use of amalgam is hazardous to patients, the health authorities in Sweden and Norway recommended in the late 1980s that no major amalgam therapy should be used when treating pregnant women. † Denmark and Finland have not specifically highlighted pregnancy, although there are general regulations to reduce the use of amalgam. † In Germany and Austria, recommendations are in place to reduce the use of amalgam in young children, pregnant women and individuals with kidney disease. These recommendations are consistent with the uncertain evidence of possible effects of dental amalgam.
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† Most other European countries have neither recommendations or restrictions on the use of amalgam. † From an environmental aspect, it is important to encourage the introduction and evaluation of new technologies for clinical dentistry. Forss and Widstrom16 have published data on the dental materials used in Sweden and Finland, following distribution of a questionnaire to 650 private dental practitioners. The most commonly used material was RBC, which was used in 74.9% of resorations, with amalgam being used in 4.8% of cases. The authors concluded that clinical dentistry in Finland had made a definite step towards the post-amalgam era. However, the authors also obtained longevity data on 54% ðn ¼ 2012Þ of the failed restorations, with these data indicating that the median age of the failed amalgam restorations was substantially greater (median age:12 years) than the median age of the failed composite restorations (median age: 5years). Mjor, in 1997,17 compared the restorative materials used by a group of clinicians ðn ¼ 177Þ who had signed up for a 3-year programme in continuing dental education during 1993 – 1995 with those from a similar survey in 1978 – 1979 ðn ¼ 85Þ: The results revealed marked changes in the prescribing of direct restrorative materials in the two surveys, with RBC materials taking over from amalgam as the routine posterior restorative material and the use of amalgam decreasing in both relative and absolute numbers. Widstrom and Forss mailed a questionnaire to 700 private dentists in Finland in January 1997, the results of which were published in 1998.18 The results reported by the respondents (82% response) indicated that use of amalgam had markedly decreased over the preceding 5 years and the use of RBC had increased. A higher proportion of male dentists than female dentists reported that they had discontinued the use of amalgam, and 77% of respondents stated that they used composite for extensive restorations in molars. Wang collated data on numbers of restored surfaces and the use of dental amalgam from the dental records of 9224 children (5 – 18 years of age) from 1978 to 1995 in Norway.19 Results indicated that the proportion of surfaces which were restored with amalgam was reduced in all age groups, with the reduction varying between 73% in the oldest age group, and 97% in the 5 year-old children. Middle East Few data are available on the use of amalgam and composite in the Middle East. However, AlNegrish
F.J.T. Burke
has conducted two surveys on the reasons for placement and replacement of amalgam and composite restorations in Jordan.20,21 Both studies used the same group of dentists, namely 16.6% ðn ¼ 241Þ of the dentists in Jordan. While the data do not specifically set out to determine the percentages of restorations placed in amalgam and composite, respondents were requested to record information for 1 month and, so, information can be gleaned on the proportional usage of amalgam and composite. During the period of the study, a total of 2239 composite restorations and 3166 amalgam restorations were placed. However, less than 10% of the composite restorations were Class II and fewer than 20% were Class I restorations, compared with the amalgam restorations which were recorded, of which all 14% were in loadbearing situations. It therefore appears that a substantial majority of dentists in Jordan elect to place amalgam rather than composite in loadbearing cavities. South America A paucity of data exists in the English language literature on the usage of restorations in amalgam and RBC. However, Gordan and co-workers have published results of a survey of the teaching of posterior RBC restorations in dental schools in Brazil.22 A questionnaire was distributed to 92 Brazilian dental schools in 1999, with 64 (70%) returning the survey. Fifty-five (87%) of the schools reported that they devoted from 5 to 55% of their curriculum time in operative dentistry to teach posterior RBC restorations. All schools reported the teaching of Class I restorations, 97% taught Class II and 87% taught three-surface (MOD) restorations in RBC. The results indicated that schools in Brazil were more favourably disposed to the teaching of posterior RBC restorations in premolars than in Europe, Japan and North America, although Brazilian schools were more conservative with RBC restorations in molars, compared with teaching in North America, Europe and Japan.22 Since it could be considered that dental schools should be leaders in education, these data could be considered to represent substantial interest in the placement of RBC restorations in posterior teeth in Brazil. Africa Few data are available regarding the usage of amalgam and RBC. A paper by Oginni and Olusie, published in 2002, on the longevity of amalgam restorations in Nigeria, states that ‘In Nigeria……dental amalgam has been used extensively as a tooth restorative material’.23 However, no data are presented to support this statement.
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results
Discussion The results of the present survey indicate widespread provision of RBC restorations in posterior teeth in a number of countries, but that amalgam is still predominant as the material of choice for dentists in a majority of the countries for which data are available. It has been considered, in 1998, that amalgam was still the most commonly used restorative material, but that there were great differences between countries in Europe.18 A number of studies have indicated that the use of amalgam as a restorative material is decreasing,6,7,9 – 13,15 – 18 but there are substantial differences in the usage of amalgam, not only in different countries in Scandinavia, but also throughout the world. Among the countries where substantial decreased use of amalgam is reported is Australia, where the use of RBC materials was reported to have increased in 74% of respondents’ practices over the 5 years preceding the survey, with the USA, Finland, and Sweden also reporting increased numbers of RBC restorations being placed. The increase in use of RBC materials is less in a number of other countries in which data are available. The increasing use of RBC materials may be considered reasonable, since the American Dental Association, following the advice of a panel of experts, have suggested that composite is now indicated for moderate-sized Class I and II restorations, as well as smaller cavities.24 The reasons for the decreased use of amalgam are unclear, but may be considered to include patients’ preference for a tooth-coloured restoration, anxieties about the use of a mercurycontaining restorative material or dentists’ preference for a particular material. The studies presented above provide little insight into the reasons for use of any given material and it could be considered that further research is indicated into dentists’ decision making, worldwide, in respect of the materials that they use.
Conclusions Within the constraints of the present study, and the relative lack of robust information, it would appear that there is few restrictions worldwide to the placement of dental amalgam, although a number of governments have provided suggested guidelines. It would further appear that amalgam use is declining, but at rates which are unclear in many countries because of the paucity of published data. Where robust data are available, amalgam
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use has been found to be decreasing in the USA, Australia and Scandinavia, with lesser decreases being apparent in the UK. It could be that the advent of low shrinkage resins which are currently under development, or self-etch composite restoratives, perhaps based on recently introduced resin composite luting materials may herald a new era of less technique-sensitive RBC materials and the final demise of the amalgam era which has prevailed for well over a century.
Acknowledgements The author wishes to thank 3M ESPE (St Paul, MN, USA) for funding the surveys of UK and Australian dentists.
References 1. Reinhardt JW, Capilouto ML. Composite resin esthetic dentistry survey in New England. Journal of the American Dental Association 1990;120:541—4. 2. Burke FJT. Patient acceptance of posterior composite restorations. Dental Update 1989;16:114—20. 3. Roulet JF. Benefits and disadvantages of tooth-coloured alternatives to amalgam. Journal of Dentistry 1997;25: 459—63. 4. Neville K, Pine C. EADPH news page. Community Dental Health 1998;15(2):128. 5. Widstrom E. Amalgam arouses hot feelings. Community Dental Health 1997;14:125—6. 6. Anon. Question of the month. Journal of the American Dental Association 1997;128:1502. 7. Brown LJ, Wall T, Wassenaar JD. Trends in resin and amalgam usage as recorded on insurance claims submitted by dentists from the early 1990s and 1998. Journal of Dental Research 2000;79(461):2542. [abstract 2542]. 8. Product Use Survey. Clinical Research Associates. CRA Newsletter, 1995:19(10):1—2. 9. Bogacki RE, Hunt RJ, del Aguila M, Smith WR. Survival analysis of posterior restorations using an insurance claims database. Operative Dentistry 2002;27:488—92. 10. Burke FJT, McHugh S, Hall AC, Randall RC, Widstrom E, Forss H. Amalgam and composite use in UK general dental practice in 2001. British Dental Journal 2003;194:613—8. 11. Burke FJT, Wilson NHF, Cheung S-W, Mjor IA. Influence of patient factors on age of restorations at failure and reasons for their placement and replacement. Journal of Dentistry 2001;29:317—24. 12. Brennan DS, Spencer AJ. Restorative service trends in private general practice in Australia:1983—1999. Journal of Dentistry 2003;31:143—51. 13. Randall RC, Meyers IA, Pitt J, Hall AC, McHugh S, Burke FJT. Amalgam and composite use in 2002 in general dental practice in Australia. Journal of Dental Research 2003;B346(82(Spec.Iss B)). 14. Fukushima M, Iwaku M, Setcos JC, Wilson NHF, Mjor IA. Teaching of posterior composite restorations in Japanese dental schools. International Dental Journal 2000;50: 407—11.
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15. Ylinen K, Lofroth G. Nordic dentists knowledge and attitudes on dental amalgam from health and environmental perspectives. Acta Odontoliga Scandinavica 2002; 60:315—20. 16. Forss H, Widstrom E. From amalgam to composite: selection of restorative materials and restoration longevity in Finland. Acta Odontoliga Scandinavica 2001;59: 57—62. 17. Mjor IA. Selection of restorative materials in general dental practice in Sweden. Acta Odontoliga Scandinavica 1997;55: 53—7. 18. Widstrom E, Forss H. Dental Practitioners’ experiences on the usefulness of restorative materials in Finland 1992— 1996. British Dental Journal 1998;185:540—2. 19. Wang NJ. Is amalgam in child dental care on its way out? Restorative materials used in children and adolescents in 1978 and 1995 in Norway. Community Dental Health 2000; 17:97—101.
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20. AlNegrish ARS. Reasons for placement and replacement of amalgam restorations in Jordan. International Dental Journal 2001;51:109—15. 21. AlNegrish ARS. Composite resin restorations: a crosssectional survey of placement and replacement in Jordan. International Dental Journal 2002;52:461—8. 22. Gordan VV, Mjor IA, Filho LCdaV, Ritter AV. Teaching of posterior resin-based composite restorations in Brazilian dental schools. Quintessence International 2000;31: 735—40. 23. Oginni O, Olusie AO. A survey of amalgam restorations in a south-western Nigerian population. Journal of Oral Rehabilitation 2002;29:295—9. 24. ADA Council on Scientific Affairs: ADA Council on Dental Benefit programs, Statement on posterior resin-based composites. Journal of the American Dental Association 1998;129:1627—8.
www.intl.elsevierhealth.com/journals/jden
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results F.J. Trevor Burke* Department of Adult Dental Care, Primary Dental Care Research Group, School of Dentistry, University of Birmingham, St Chad’s Queensway, Birmingham B4 6NN, UK Received 2 December 2003; accepted 3 February 2004
KEYWORDS Amalgam; Resin-based composite; Usage; Government; Regulations
Summary Objectives. To review governmental guidelines on amalgam use worldwide and to assess trends in the usage of amalgam and composite materials in restoration of posterior teeth. Methods. A letter was sent to 24 government health agencies or representative organisations requesting details of regulations pertaining to amalgam use. A literature search was carried out in order to identify papers in which the incidence of amalgam and composite restorations was stated. Results. Ten replies were received, indicating few restrictions on the use of amalgam. Results obtained from published work appear to indicate that amalgam use is declining, but at rates which are unclear in many countries because of the paucity of published data. Amalgam use has been found to be decreasing in the USA, Australia and Scandinavia, with lesser decreases being apparent in the UK. Conclusions. There are few restrictions to the use of amalgam worldwide. In countries where data are available, such as USA, Australia and Scandinavia, amalgam use has been found to be decreasing, with smaller decreases being apparent in the UK. q 2004 Elsevier Ltd. All rights reserved.
Introduction There is patient interest in tooth-coloured restorations in posterior teeth, both in the UK and the USA,1,2 but worldwide, it is likely that amalgam restorations are more frequently used than tooth-coloured materials. However, in a world in which so much has changed over the past century, it may be considered peculiar that dentists *Tel.: þ44-121-237-2767; fax: þ 44-121-625-8815. E-mail address: [email protected]
are placing a material in posterior teeth, which is not much changed from that used over a hundred years ago. Notwithstanding the appearance of their restorations, it is possible that patients may request tooth-coloured restorations because of worries about mercury present in dental amalgam. 3 Government agencies may also seek amalgam alternatives for environmental reasons. It is the purpose of this paper to review governmental regulations on amalgam, worldwide and to review the literature in order to determine the incidence of amalgam and composite use for
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posterior teeth in the countries where data are available.
Materials and methods Governmental regulations Names and addresses of government health agencies or representative organisations were obtained from web sites and from the British Dental Association Information Centre. A letter was sent to 24 such agencies requesting details, if they were available, of regulations pertaining to amalgam use. A second letter was sent to those who had not responded within three months.
Incidence of amalgam and composite usage A Medline literature search was carried out in order to identify papers, published since 1998, in which the incidence of amalgam and resin-based composite (RBC) restorations was stated. In addition, the author’s library of published articles was searched.
Results Governmental regulations Responses were received from 10 governmental or representative agencies in response to the first mailing of the letter requesting information, and two replies were received after the second mailing. One letter was returned. Replies, which generally were brief or provided directions to a relevant web site, were translated into English ðn ¼ 2Þ where necessary. A summary of the information received is detailed in Table 1. From the responses received, it would appear that there are few restrictions worldwide to the placement of dental amalgam. Additional information, on restrictions on the use of amalgam in Europe, is contained in the European Association of Dental Public Health (EADPH) news page in a 1998 issue of Community Dental Health.4 This stated that new advice on the use of amalgam had been sent to general dental practitioners in the UK, suggesting that it would be ‘prudent’ to avoid the use of amalgam during pregnancy. This advice was precautionary, pending further research. Dr Eva Widstrom Chief Dental Officer, National Research and Development Centre for Welfare and Health, Helsinki, Finland, provided further insight into regulations on amalgam usage in
F.J.T. Burke
an editorial in Community Dental Health in September 1997.5 The principal points addressed in this editorial included:
† Several expert groups in different countries have evaluated the scientific research on the health effects of dental amalgam. All these groups concluded that there is no direct evidence of an adverse effect of mercury from amalgam restorations on general health. † Amalgam, when properly handled, has not been shown to be hazardous to dental personnel. † Health authorities in some countries have taken a rather cautious attitude to the use of amalgam in dentistry. Major amalgam therapy has not been recommended when treating pregnant women and young children or patients with renal disease. To avoid corrosion amalgam fillings should not be placed in contact with restorations of other metals. The rationale behind these recommendations has been a desire to lower the exposure to a potentially hazardous substance during sensitive periods of life. † Amalgam separators in the wastelines of dental units are a legal requirement in some countries and there are pressures to introduce them in many more countries. † In 1995, the Commission of the European Union appointed its own expert group to clarify the reasons why some member states had restrictions on the use of, and questioned the safety of, dental amalgam. Despite the various local, regional and global research projects by different expert groups, about 250,000 dentists within the EU continue to treat their patients using amalgam filings.
Incidence of amalgam and RBC usage for restoration of loadbearing cavities in posterior teeth Data in respect of amalgam and composite usage worldwide was scarce, so the search was extended to include relevant papers published since 1995. USA Results of the ‘Question of the month’ feature in the November 1997 issue of the Journal of the American Dental Association produced a response from 355 readers, with 33% of these respondents stating that dental amalgam was not their material of choice, 65% indicating dental amalgam remained their restorative material of choice and eight respondents stating that they used amalgam about 50% of the time.6 Many of those who responded
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results
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Table 1 Representative statements on amalgam from government or representative agencies. Country and name of agency
Comments from governmental or representative agency
USA USA Food and Drug Administration
FDA and other organisations of the USPHS continue to investigate the safety of amalgam used in dental restorations. No valid scientific evidence has ever shown that amalgams cause harm to patients, except in the rare case of allergy. Since amalgam is a CE-marked product approved by a notified body in the Union, there are no regulations confining its use in Sweden. However, the Swedish Govt has abolished amalgam from the insurance reimbursement system. There is agreement between the providers of dental health (county councils) and the Ministry of Social Affairs not to use amalgam on patients below 20 years of age. The National Board of Health and Welfare recommends not to remove amalgam restorations during pregnancy. Proposed guidelines encourage dentists to minimise their use of amalgam by using an alternative whenever possible. The desire to reduce the use of amalgam is not based on a particular piece of research, but on an overall assessment of research and experience available to the dept. since 1991. No regulations: no exact data on amalgam use, but figures available on use. Of 4000 clients of a major deliverer only 50 clients order amalgam. Amalgam fillings in molar teeth permitted until further notice. There are no laws or regulations relating to the use of dental amalgam in Ireland. Amalgam is a medical device and therefore falls under the Medical Device Regulations 2002. All devices have to meet safety requirements. A way to meet this is to conform to harmonised technical standards. There are none for dental amalgam. Japan does not have any regulation prohibiting or restricting the placement of dental amalgam restorations. Due to widespread use of composite resin, amalgam has not been used much recently. ADC does not have a policy, as such, for the use of dental amalgam. Amalgam contains mercury and other metals. The produced must fulfil all the uniformly regulated fundamental requirements governed by the European Union. Currently neither the Federal Institution for Drug and MedicineProducts have justified suspicion that mercury from amalgam has a negative influence on health. In pregnant women, extensive restorative procedures should be avoided. When treating pregnant women amalgam restorations should not be placed or removed. As matters stand, there is no proof that mercury from amalgam restorations of the mother could cause any harm to the health of the unborn child. Major renal impairment represents a relative contraindication for the use of amalgam.
Sweden National Board of Health and Welfare, Stockholm
Norway Norwegian Directorate for Health and Social Welfare
Finland National Institute for Medicine, Medical Devices, Helsinki Denmark Danish Environmental Protection Agency Ireland Dental Council, Dublin United Kingdom Department of Health, London
Japan Japan Dental Association
Australia Australian Dental Council Germany Bundesministerium fur Gesundheit
‘yes’ to the use of amalgam stated that they preferred amalgam to RBC because of what they termed composite’s failures, namely, microleakage, unacceptable wear, sensitivity and lack of durability. Of the 113 respondents who stated that amalgam was not their restorative material of choice, 27 did not use amalgam at all. Data on amalgam and RBC use up to 1998 are available by way of a survey carried out by
the American Dental Association. Results from this indicated that almost half of the Class I and one third of Class II restorations placed in the USA were tooth-coloured.7 It may further be considered that a growing number of dentists are restricting their practices to the use of RBCs as opposed to amalgam in the US, where in 1995, approximately 20% of intra-coronal restorations were tooth-coloured,8 this proportion rising, by the year 1998, to 47% for
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single-surface direct-placement restorations and circa 30% for multiple surface restorations.7 Further, data on amalgam and RBC use are available from the Washington Dental Service, which has a claim-based data warehouse containing details of dental services provided to 1.5 million patients.9 Data obtained from this source indicated that the use of RBC exceeded amalgam in 1999. UK Recently published data on UK dentists’ use of amalgam and composite are available by way of a survey to 1000 dentists, for which 654 replies were received.10 Regarding choice of material, 100% of respondents cited clinical indication as the most influential factor, although patients’ aesthetic demands (99%), patients’ choice (95%) and patients’ financial situation (92%) were also reported to influence respondents’ choice. Thirty-five percent of respondents used RBC ‘sometimes’, 15% ‘often’, and 1% ‘always’ in extensive loadbearing cavities in molar teeth. Forty percent ðn ¼ 242Þ of respondents considered that secondary caries had increased as a result of decreased use of amalgam, while 46% ðn ¼ 280Þ of respondents considered that the need for root fillings had increased. Thirty-nine percent ðn ¼ 239Þ of respondents considered that loss of fillings had increased as a result of decreased amalgam use, although 47% ðn ¼ 285Þ considered that this had remained stable. For RBC restorations in posterior teeth, 92% ‘always’, ‘often’ or ‘sometimes’ used the total etch technique and 53% never used rubber dam. Seventy percent of respondents agreed with the statement ‘discontinuation of amalgam restricts a dentist’s ability to adequately treat patients’. Eighty-one percent considered that the growth in the use of composites would increase the total cost of oral health care. It was concluded that 49% of the respondents from England and Wales seldom placed large composite restorations in molar teeth and that their choice of material was influenced greatly by clinical indications and patient’s aesthetic demands. However, the use of RBC for restoration of loadbearing cavities in posterior teeth in the UK may be influenced by the fact that such restorations are not permitted under the National Health Service Regulations. Results of a cross-sectional study carried out in 1999, and using data generated by thirty general dental practitioners have indicated that one quarter of Class I restorations placed in the UK are made in RBC materials.11
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Australia Recent data are available from Australia from a couple of sources. A paper by Brennan and Spencer, which reviewed restorative treatment trends from 1983 to 1999, has provided timely data on the use of amalgam and composite in Australia.12 This work used a series of mailed surveys to a random sample of dentists in 1983 – 1984, 1988 – 1989, 1993 – 1994, and 1998 –1999, with response rates of over 70% to each. The overall number of restorative treatments declined during the study period, reflecting a steady decline in the number of amalgams placed, from a mean of 1275 per dentist in 1983 – 1984 to 437 in 1988 – 1989. However, the number of composites placed showed an increase between the 1993 –1994 and 1988 –1989 surveys, from 508 per dentist per annum to 694, respectively. The results of a survey to 1000 general practitioner dentists in Australia were presented at the International Association of Dental Research meeting in Gothenburg in June 2003.13 A total of 560 replies were received. Regarding choice of material, 99% of respondents cited clinical indication as an influencing factor, although patients’ aesthetic demands (99% of respondents), patients’ wish (96%), patients’ financial situation (82%), and lecturers’ suggestions (72%) were also reported to influence respondents’ choice of materials. Twelve percent of respondents used composite ‘always’, 29% ‘often’, 32% ‘sometimes’, 23% ‘seldom’, and 4% ‘never’ in extensive loadbearing cavities in molar teeth. Fifty-nine percent of respondents reported a decrease in amalgam use over the previous five years. Sixty-eight percent of respondents agreed with the statement ‘discontinuation of amalgam restricts a dentist’s ability to adequately treat patients’. Seventy-five percent considered that the growth in the use of composites increased the total cost of oral health care. The survey concluded that 73% of the respondents from Australia place large composite restorations in molar teeth. It is apparent from the two related surveys10,13 cited above that the use of resin composite for the restoration of posterior teeth was much more prevalent in Australia than in the UK. This difference may, however, be due, at least in part, to the guidance issued by the General Dental Services of the Department of Health in the UK, which does not allow provision of RBC restorations in loadbearing surfaces of posterior teeth, while no such restications apply in Australia.
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results Dentists in the UK and Australia were in general agreement on a number of the statements in the study questionnsire, such as: † Due to environmental reasons we should stop using amalgam (Agree: 53% UK, 48% Australia) † Pregnant dentists should not provide amalgam restorations (Agree: 60% UK, 47% Australia) † Discontinuation of amalgam would restrict dentists’ability to treat patients’ oral health (Agree: 83% UK, 75% Australia) † Growth in use of composites is increasing the total cost of oral health care (Agree: 95% UK, 89% Australia) † A low shrink composite would be a clinical advantage (Agree:98% UK, 97% Australia). Key differences between the UK and Australia included: † Reported use of amalgam decreased 9% more in Australia than in UK over past 5 years (59% cf 50%) † Reported use of composite increased more in Australia than in England over past 5 years (74% cf 62%) † Patients’ aesthetic demands influence material choice more in Australia (73% Australia cf 62% UK) † Agreement with statement ‘The use of amalgam will be discontinued by 2005’ (89% UK compared with 76% Australia). Japan A shown in Table 1, the Japan Dental Association, in 2002, stated that ‘Japan does not have any regulation prohibiting or restricting the placement of dental amalgam restorations. Due to widespread use of composite resin, amalgam has not been used much recently’. Other than this statement, there is little information on the use of RBC restorations in posterior teeth. However, results of a survey, published in 2000, into the teaching of posterior composite restorations in Japanses dental schools (response rate 93%) indicated that 93% of the respondent schools taught the use of RBC materials in Class I restorations, with most schools anticipating that the proportion of time devoted to the teching of posterior composite restortions would increase in the following five years.14 Scandinavia A paper by Ylinen and Lofroth, published in 2002, is a fruitful source of information on the use of dental amalgam in Nordic countries.15 This work used a 25-question postal questionnaire to random samples of dentists in Denmark, Finland, Norway
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and Sweden to determine attitudes to amalgam as a halth and environmental issue, and social and ethical aspects of amalgam use. The results indicated differences in amalgam usage in the four countries surveyed, with only one dentist from Finland (1%) and two (1%) from Sweden having used amalgam in a child under 12 years of age during the year preceding the survey. By contrast, 61% of the respondents from Denmark, and 33% of the respondents from Norway had used amalgam in this age group. For adult patients, the percentage using amalgam was higher in all the countries assessed, ranging from 28% in Finland, 40% in Sweden, 88% in Norway and 92% in Denmark. The dentists who had stopped using amalgam were asked when they had stopped using it, with the number not using amalgam being found to grow slowly every year. Principal alternatives to amalgam in all four countries were found to be glass ionomer for children and RBC for adults. Most respondent dentists considered amalgam to be a health risk, at least for some patients, with the percentage answering ‘no risk’ ranging from 33% in Denmark to 2% in Norway. However, the majority of dentists in all countries wanted to keep amalgam as a restorative material. A majority of the respondents considered both amalgam and RBC to be potentially harmful to patients and suggested that efforts should continue to develop better alternatives to both materials. Information on amalgam use in Europe was provided in the EADPH News Page in 1998.3 This provided information as follows: † In Finland, the use of amalgam has been reducing for some time, reflecting the improved health of the younger generation. † In 1996, approximately 7% of fillings provided by private practitioners in Finland for women aged between 20 and 40 years were amalgam. † Although there is no clear scientific evidence showing that the use of amalgam is hazardous to patients, the health authorities in Sweden and Norway recommended in the late 1980s that no major amalgam therapy should be used when treating pregnant women. † Denmark and Finland have not specifically highlighted pregnancy, although there are general regulations to reduce the use of amalgam. † In Germany and Austria, recommendations are in place to reduce the use of amalgam in young children, pregnant women and individuals with kidney disease. These recommendations are consistent with the uncertain evidence of possible effects of dental amalgam.
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† Most other European countries have neither recommendations or restrictions on the use of amalgam. † From an environmental aspect, it is important to encourage the introduction and evaluation of new technologies for clinical dentistry. Forss and Widstrom16 have published data on the dental materials used in Sweden and Finland, following distribution of a questionnaire to 650 private dental practitioners. The most commonly used material was RBC, which was used in 74.9% of resorations, with amalgam being used in 4.8% of cases. The authors concluded that clinical dentistry in Finland had made a definite step towards the post-amalgam era. However, the authors also obtained longevity data on 54% ðn ¼ 2012Þ of the failed restorations, with these data indicating that the median age of the failed amalgam restorations was substantially greater (median age:12 years) than the median age of the failed composite restorations (median age: 5years). Mjor, in 1997,17 compared the restorative materials used by a group of clinicians ðn ¼ 177Þ who had signed up for a 3-year programme in continuing dental education during 1993 – 1995 with those from a similar survey in 1978 – 1979 ðn ¼ 85Þ: The results revealed marked changes in the prescribing of direct restrorative materials in the two surveys, with RBC materials taking over from amalgam as the routine posterior restorative material and the use of amalgam decreasing in both relative and absolute numbers. Widstrom and Forss mailed a questionnaire to 700 private dentists in Finland in January 1997, the results of which were published in 1998.18 The results reported by the respondents (82% response) indicated that use of amalgam had markedly decreased over the preceding 5 years and the use of RBC had increased. A higher proportion of male dentists than female dentists reported that they had discontinued the use of amalgam, and 77% of respondents stated that they used composite for extensive restorations in molars. Wang collated data on numbers of restored surfaces and the use of dental amalgam from the dental records of 9224 children (5 – 18 years of age) from 1978 to 1995 in Norway.19 Results indicated that the proportion of surfaces which were restored with amalgam was reduced in all age groups, with the reduction varying between 73% in the oldest age group, and 97% in the 5 year-old children. Middle East Few data are available on the use of amalgam and composite in the Middle East. However, AlNegrish
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has conducted two surveys on the reasons for placement and replacement of amalgam and composite restorations in Jordan.20,21 Both studies used the same group of dentists, namely 16.6% ðn ¼ 241Þ of the dentists in Jordan. While the data do not specifically set out to determine the percentages of restorations placed in amalgam and composite, respondents were requested to record information for 1 month and, so, information can be gleaned on the proportional usage of amalgam and composite. During the period of the study, a total of 2239 composite restorations and 3166 amalgam restorations were placed. However, less than 10% of the composite restorations were Class II and fewer than 20% were Class I restorations, compared with the amalgam restorations which were recorded, of which all 14% were in loadbearing situations. It therefore appears that a substantial majority of dentists in Jordan elect to place amalgam rather than composite in loadbearing cavities. South America A paucity of data exists in the English language literature on the usage of restorations in amalgam and RBC. However, Gordan and co-workers have published results of a survey of the teaching of posterior RBC restorations in dental schools in Brazil.22 A questionnaire was distributed to 92 Brazilian dental schools in 1999, with 64 (70%) returning the survey. Fifty-five (87%) of the schools reported that they devoted from 5 to 55% of their curriculum time in operative dentistry to teach posterior RBC restorations. All schools reported the teaching of Class I restorations, 97% taught Class II and 87% taught three-surface (MOD) restorations in RBC. The results indicated that schools in Brazil were more favourably disposed to the teaching of posterior RBC restorations in premolars than in Europe, Japan and North America, although Brazilian schools were more conservative with RBC restorations in molars, compared with teaching in North America, Europe and Japan.22 Since it could be considered that dental schools should be leaders in education, these data could be considered to represent substantial interest in the placement of RBC restorations in posterior teeth in Brazil. Africa Few data are available regarding the usage of amalgam and RBC. A paper by Oginni and Olusie, published in 2002, on the longevity of amalgam restorations in Nigeria, states that ‘In Nigeria……dental amalgam has been used extensively as a tooth restorative material’.23 However, no data are presented to support this statement.
Amalgam to tooth-coloured materials—implications for clinical practice and dental education: governmental restrictions and amalgam-usage survey results
Discussion The results of the present survey indicate widespread provision of RBC restorations in posterior teeth in a number of countries, but that amalgam is still predominant as the material of choice for dentists in a majority of the countries for which data are available. It has been considered, in 1998, that amalgam was still the most commonly used restorative material, but that there were great differences between countries in Europe.18 A number of studies have indicated that the use of amalgam as a restorative material is decreasing,6,7,9 – 13,15 – 18 but there are substantial differences in the usage of amalgam, not only in different countries in Scandinavia, but also throughout the world. Among the countries where substantial decreased use of amalgam is reported is Australia, where the use of RBC materials was reported to have increased in 74% of respondents’ practices over the 5 years preceding the survey, with the USA, Finland, and Sweden also reporting increased numbers of RBC restorations being placed. The increase in use of RBC materials is less in a number of other countries in which data are available. The increasing use of RBC materials may be considered reasonable, since the American Dental Association, following the advice of a panel of experts, have suggested that composite is now indicated for moderate-sized Class I and II restorations, as well as smaller cavities.24 The reasons for the decreased use of amalgam are unclear, but may be considered to include patients’ preference for a tooth-coloured restoration, anxieties about the use of a mercurycontaining restorative material or dentists’ preference for a particular material. The studies presented above provide little insight into the reasons for use of any given material and it could be considered that further research is indicated into dentists’ decision making, worldwide, in respect of the materials that they use.
Conclusions Within the constraints of the present study, and the relative lack of robust information, it would appear that there is few restrictions worldwide to the placement of dental amalgam, although a number of governments have provided suggested guidelines. It would further appear that amalgam use is declining, but at rates which are unclear in many countries because of the paucity of published data. Where robust data are available, amalgam
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use has been found to be decreasing in the USA, Australia and Scandinavia, with lesser decreases being apparent in the UK. It could be that the advent of low shrinkage resins which are currently under development, or self-etch composite restoratives, perhaps based on recently introduced resin composite luting materials may herald a new era of less technique-sensitive RBC materials and the final demise of the amalgam era which has prevailed for well over a century.
Acknowledgements The author wishes to thank 3M ESPE (St Paul, MN, USA) for funding the surveys of UK and Australian dentists.
References 1. Reinhardt JW, Capilouto ML. Composite resin esthetic dentistry survey in New England. Journal of the American Dental Association 1990;120:541—4. 2. Burke FJT. Patient acceptance of posterior composite restorations. Dental Update 1989;16:114—20. 3. Roulet JF. Benefits and disadvantages of tooth-coloured alternatives to amalgam. Journal of Dentistry 1997;25: 459—63. 4. Neville K, Pine C. EADPH news page. Community Dental Health 1998;15(2):128. 5. Widstrom E. Amalgam arouses hot feelings. Community Dental Health 1997;14:125—6. 6. Anon. Question of the month. Journal of the American Dental Association 1997;128:1502. 7. Brown LJ, Wall T, Wassenaar JD. Trends in resin and amalgam usage as recorded on insurance claims submitted by dentists from the early 1990s and 1998. Journal of Dental Research 2000;79(461):2542. [abstract 2542]. 8. Product Use Survey. Clinical Research Associates. CRA Newsletter, 1995:19(10):1—2. 9. Bogacki RE, Hunt RJ, del Aguila M, Smith WR. Survival analysis of posterior restorations using an insurance claims database. Operative Dentistry 2002;27:488—92. 10. Burke FJT, McHugh S, Hall AC, Randall RC, Widstrom E, Forss H. Amalgam and composite use in UK general dental practice in 2001. British Dental Journal 2003;194:613—8. 11. Burke FJT, Wilson NHF, Cheung S-W, Mjor IA. Influence of patient factors on age of restorations at failure and reasons for their placement and replacement. Journal of Dentistry 2001;29:317—24. 12. Brennan DS, Spencer AJ. Restorative service trends in private general practice in Australia:1983—1999. Journal of Dentistry 2003;31:143—51. 13. Randall RC, Meyers IA, Pitt J, Hall AC, McHugh S, Burke FJT. Amalgam and composite use in 2002 in general dental practice in Australia. Journal of Dental Research 2003;B346(82(Spec.Iss B)). 14. Fukushima M, Iwaku M, Setcos JC, Wilson NHF, Mjor IA. Teaching of posterior composite restorations in Japanese dental schools. International Dental Journal 2000;50: 407—11.
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15. Ylinen K, Lofroth G. Nordic dentists knowledge and attitudes on dental amalgam from health and environmental perspectives. Acta Odontoliga Scandinavica 2002; 60:315—20. 16. Forss H, Widstrom E. From amalgam to composite: selection of restorative materials and restoration longevity in Finland. Acta Odontoliga Scandinavica 2001;59: 57—62. 17. Mjor IA. Selection of restorative materials in general dental practice in Sweden. Acta Odontoliga Scandinavica 1997;55: 53—7. 18. Widstrom E, Forss H. Dental Practitioners’ experiences on the usefulness of restorative materials in Finland 1992— 1996. British Dental Journal 1998;185:540—2. 19. Wang NJ. Is amalgam in child dental care on its way out? Restorative materials used in children and adolescents in 1978 and 1995 in Norway. Community Dental Health 2000; 17:97—101.
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20. AlNegrish ARS. Reasons for placement and replacement of amalgam restorations in Jordan. International Dental Journal 2001;51:109—15. 21. AlNegrish ARS. Composite resin restorations: a crosssectional survey of placement and replacement in Jordan. International Dental Journal 2002;52:461—8. 22. Gordan VV, Mjor IA, Filho LCdaV, Ritter AV. Teaching of posterior resin-based composite restorations in Brazilian dental schools. Quintessence International 2000;31: 735—40. 23. Oginni O, Olusie AO. A survey of amalgam restorations in a south-western Nigerian population. Journal of Oral Rehabilitation 2002;29:295—9. 24. ADA Council on Scientific Affairs: ADA Council on Dental Benefit programs, Statement on posterior resin-based composites. Journal of the American Dental Association 1998;129:1627—8.