Amalgam phase down: baseline data preceding implementation in Nigeria

Objective: The Minimata Convention on mercury includes amalgam phase-down and eventual phase-out from dentistry. To aid its subsequent evaluation it is important to have baseline data of amalgam use in a locality prior to implementing a phase-down. Methodology: Records of patients spanning 5 years from January 2011 to January 2016 were analysed to determine and the compare frequency of amalgam usage with other dental materials for carious teeth restorations in a Nigerian university teaching hospital. Classes of cavities restored and cadres of operators who employed the different materials were included. Institutional ethics committee approval was obtained prior to commencing the study. Results: 2,058 patients’ records were retrieved, 59% females and 41% males. Their ages ranged 19–80 years, mean 33.5 ± 12.7 years, young adults 20–39 years old were the majority (62.9%). Filling materials included 57.5% amalgam, 17.6% glass ionomer cement (GIC) and 24.9% resin composite. Class I restorations constituted 70.5% of amalgam restorations, while Class II restorations made up 29.4% and Class V restorations accounted for 0.1%. Undergraduate dental students placed most of the amalgam restorations (60.5%), and 78.9% of all their restorations were amalgam. Less experienced dentists used all materials equally; the more experienced dentists placed more composite resin and GIC (43.3%). Conclusion: Amalgam fillings constituted nearly 60% of the restorations of carious teeth. Training of dental students in placement of non-mercury alternatives to amalgam and Minimum Intervention Dentistry needs to be emphasized in dental schools. Phase-down of amalgam should be intensified in Nigeria with the ultimate aim of a phase-out in line with the Minamata Convention.Key words: Amalgam, phase-down, Nigeria, dental caries     

Trends in material choice for direct restorations by final year students from University College Cork 2004-2009

Traditionally, undergraduate students in University College Cork (UCC) have been taught to use amalgam as the first choice material for direct restoration of posterior cavities. Since 2005 the use of composite resins has replaced amalgam as the first choice material. An audit was conducted of all direct restorations placed by final year students from UCC from 2004 until 2009. Results showed that over a six year period, final year UCC dental undergraduate students placed proportionately more direct composite resin restorations and significantly fewer amalgam restorations. The need for and undergraduate exposure to, provision of amalgam restorations may have to be revisited.     

The amalgam-free dental school

OBJECTIVES: To review the change in teaching of Restorative Dentistry at Nijmegen dental school over the period 1986 to the present. KEY POINTS: In 1986, class I and II resin composite restorations were included in the pre-clinical program. However, these courses still started with class I and II amalgam restorations. From 1990 on, the number of amalgam restorations placed in the clinic gradually decreased while the number of resin composite restorations increased. Meanwhile, resin composite had become the first choice for treatment of primary caries (class I and class II) lesions. Finally in 1994, the pre-clinical training started with resin composite restorations before dental amalgam was taught and the advantage of a minimal preparation was further emphasized. Since 2001 the teaching of dental amalgam ceased at the dental school. This was not an abrupt change but the result of a long transitional stage during which it was gradually substituted by resin composite. This step-by-step introduction allowed the acceptance of composite resin by the staff as an alternative for dental amalgam in posterior restorations. As in 2001 students placed only 2.5 amalgam restorations before graduation, it was decided to stop with the pre-clinical training program. CONCLUSIONS: The introduction of resin composites meant an important change in teaching restorative dentistry at Nijmegen dental school. It was not just a change in materials and techniques but also a change in treatment philosophy. The reduced need for preparation and the strengthening effect on the remaining tooth were the principal reasons for the shift from dental amalgam to adhesive dentistry with resin composite at Nijmegen dental school.     

Posterior dental restoration material choices in privately insured people in the United States, 2017 through 2019

BackgroundIn the context of evolving dental materials and techniques and a national agenda to phasedown use of dental amalgam, estimates of dental amalgam placement are necessary for monitoring purposes.MethodsNumbers of amalgam and composite posterior restorations from 2017 through 2019 were calculated using retrospective dental claims analysis of privately insured patients. Kruskal-Wallis and multilevel, multivariable negative binomial regression models were used to test for differences in rates of amalgam and composite restoration placement by age group, sex, urban or rural area, and percentage race and ethnicity area distribution. Statistical significance was set at 0.05, with Benjamini-Hochberg correction for false discovery rate.ResultsThe rate of amalgam restorations declined over time from a mean of 6.29 per 100 patients in 2017 to 4.78 per 100 patients in 2019, whereas the composite restoration rate increased from 27.6 per 100 patients in 2017 to 28.8 per 100 in 2019. The mean number of amalgam restorations placed per person were lowest in females compared with males, in urban areas compared with rural areas, and in areas with more than 75% non-Hispanic White residents.ConclusionsAmalgam restoration placements in privately insured people in the United States declined from 2017 through 2019. Amalgam restoration placements may be unevenly distributed by location.Practical ImplicationsAchieving further declines of dental amalgam use may require changes to insurance coverage, incentives, and provider training as well as augmented disease prevention and health promotion efforts. These efforts should focus particularly on groups with high caries risk or higher rates of amalgam placement.     

Teaching of posterior composite resin restorations in undergraduate dental schools in Ireland and the United Kingdom

PURPOSE: The aim of this study was to investigate the current teaching of posterior composite resin restorations to undergraduate dental students in Ireland and the United Kingdom (UK). The investigation was a follow-up to a survey undertaken in 1997. MATERIALS AND METHODS: A questionnaire was distributed by e-mail to the Heads of Departments of Restorative Dentistry/Units of Operative Dentistry in each of the 15 dental schools with undergraduate dental degree programmes in Ireland and the UK. The questionnaire sought information relating to the teaching of posterior composite resin restorations in each dental school. RESULTS: Fifteen completed questionnaires were returned (response rate = 100%). All schools (n = 15) taught the placement of composite resin restorations in occlusal cavities, 14 schools taught composite resin placement in two-surface occlusoproximal cavities and nine schools taught composite resin placement in three-surface occlusoproximal cavities. Respondents anticipated that the amount of preclinical teaching of posterior composite resin placement will increase twofold over the next 5 years, whilst the corresponding teaching of amalgam will fall to two-thirds its current level. Variation was found between dental schools in the teaching of the principles of cavity design, contraindications to placement, indications for lining and basing techniques, matrix and wedging techniques, and the use of curing lights. CONCLUSIONS: The amount of teaching of posterior composite resin restorations in undergraduate dental schools in Ireland and the UK has increased since the time of a previous survey in 1997. Composite resin may soon equal or overtake amalgam as the material of choice when restoring posterior cavities in Irish and UK dental schools. There was, however, much variation in the nature and extent of the teaching and the techniques taught.     

The future of dental amalgam

This paper is a comment on 'The enigma of dental amalgam' by Carl Leinfelder published in 2004 in the Journal of Esthetic and Restorative Dentistry. In that paper a warning is stated against a too abrupt change from amalgam towards resin composite, because this will bring a lot of clinical problems due to the limited skills of todays' dentists in placing posterior composite resin restorations. However, the situation in The Netherlands is different since a gradual changeover from amalgam towards resin composites has taken place during the last decades and dental schools have skipped training in placing amalgam restorations out of the curriculum. Clinical studies on the longevity of amalgam and resin composite restorations placed by dental students and dentists who are experienced in both composite resin and amalgam placement show a comparable and acceptable annual failure rate for those restorations. It is concluded that a gradual changeover from amalgam towards composite resin is preferred to avoid clinical problems.     

Three-year clinical performance of composite restorations placed by undergraduate dental students

This retrospective study evaluated the clinical performance and the reasons for failure of anterior and posterior composite restorations placed by undergraduate dental students over a 3-year period. All cavities were restored using Prime & Bond 2.1 and TPH (Dentsply), according to the manufacturer's indications. One hundred and two patients who had received composite restorations by third and forth year undergraduate students were recalled and examined to analyze the quality of the restorations. The restorations were evaluated using the modified USPHS system. Two hundred and fifty-six composite restorations, 170 in anterior teeth and 86 in posterior teeth, were evaluated. Eighty-five percent of the restorations were considered satisfactory after 3 years. Class II and class IV restorations presented the highest prevalence of failure. Loss of the restoration and deficient marginal adaptation were the main causes of failure. No restoration failed due to secondary caries. Most restorations placed by dental students were considered satisfactory after long-term evaluation. Failure was more prevalent in larger restorations and was not associated with secondary caries.     

Atraumatic restorative treatment (ART): a three-year clinical study in Malawi--comparison of conventional amalgam and ART restorations

OBJECTIVE: This study compares the quality of class I restorations made with the atraumatic restorative treatment (ART) technique and conventional class I amalgam restorations. METHODS: The study was carried out among secondary school students in Mzuzu, Malawi. First-year students in 1987 who needed at least two class I restorations were selected. Based on a split-mouth design, each participant received both ART and conventional restorations. The 89 pairs of class I cavities were divided randomly into two groups, since two different cermet ionomer cement (CIC) filling materials were used. Impressions of the restorations and subsequent models were made shortly after restoration, after six months, one year, two years, and three years. The quality of the restorations was determined on the models following the US Public Health Service criteria. Bulk fracture, contour, marginal integrity, and surface texture of the restorations were recorded and evaluated separately. Survival rates were determined by the resultant score of all criteria. RESULTS: Though conventional amalgam restorations performed better on all criteria, this difference was significant only for the contour criterion. The survival rates of ART restorations after three years (81.0%) were lower than those of amalgam restorations (90.4%) (P=.067). CONCLUSIONS: The quality of ART class I restorations is competitive with that of conventional amalgam restorations.     

Potential side effects of dental amalgam restorations

The aim of this study was to explore a possible association between health status and self-reported adverse effects related to dental amalgam restorations. A group of 50 consecutive patients (index group), referred for complaints self-related to dental amalgam restorations, was compared with a control group of individuals matched by age, sex and postal zip code. The patients underwent an oral, stomatognathic, medical and clinical chemistry examination. Mercury levels were examined in blood, urine and hair. The results revealed that somatic diseases were more common in the index group (38% versus 6%). Symptoms related to cranio-mandibular dysfunction were reported by 74% of the patients in the index group versus 24% in the control group, and were diagnosed in 62% and 36%, respectively. The oral health status and the number of amalgam surfaces were similar in the 2 groups. No positive skin patch test to mercury was found in any of the groups. The estimated mercury intake from fish consumption, occupational exposure, and mercury levels in blood and urine were also similar and far below levels, where negative health effects would be expected. The correlation between the number of amalgam surfaces and mercury levels in plasma and urine ( r = 0.43) indicated a release of mercury from dental amalgam restorations in both groups. Since the mercury levels were similar among index patients and controls, mercury was not a likely cause of the impaired health reported by the patients.     

Longevity of glass ceramic inlays and amalgam – results up to 6 years

Ceramic inlays are discussed as one option for the substitution of amalgam restorations. The purpose of this study was to determine the longevity of glass ceramic inlays and amalgam restorations placed by the author: 123 class I and class II Dicor inlays placed with adhesive techniques and 163 amalgam class I and class II restorations were investigated. The observation time for the inlays varied from 4 to 82 months. The inlays were clinically investigated using modified USPHS criteria and documented photographically. Kaplan-Meier statistics were used to calculate the survival rate. From the 123 evaluated inlays 12 inlays (9.7%) failed: 7 due to fractures, 4 because of endodontic problems and 1 inlay was replaced due to persisting postoperative pain. All fractures could be explained by case selection errors. According to the Kaplan-Meier method, the estimated success rate after 6 years was 76% for the Dicor inlays and 87% for the amalgam restorations (control group). The difference was not statistically significant. It was concluded that Dicor inlays may be used as a successful alternative to amalgam.     

Influence of the method of funding on the age of failed restorations in general dental practice in the UK

OBJECTIVE: This study examined the effect of the method of funding treatment on the age of restorations at the time of replacement. METHOD: A group of general dental practitioners were recruited to take part in the study. Each participant was asked to record the reason for placement and replacement of restorations. The age and class of the restoration being replaced was also recorded, together with details of the material being used and the material being replaced. Details of the method of payment of the failed restoration were recorded. RESULTS: Details of the reason for placement/replacement were received for 3,196 restorations from 32 GDPs. Of the restorations placed, 54% were amalgam, 32% composite, 8% compomer and 7% glass ionomer. The age of restorations at the time of replacement was significantly associated with the method of payment for the restoration, with restorations placed in the Armed Forces having been in service significantly longer at the time of their replacement than restorations placed under NHS regulations. CONCLUSION: Statistical analysis indicated that restorations placed within the NHS regulations were replaced at a significantly lower age than restorations placed under the other funding arrangements investigated.     

Plasma-selenium, glutathione peroxidase in erythrocytes and mercury in plasma in patients allegedly subject to oral galvanism

Abstract – Twelve patients with subjective symptoms, ascribed by the patients themselves to mercury released from dental restorations, were investigated. In addition to a general dental examination the following parameters were registered: the total number of amalgam surfaces in the mouth; potential and polarization of existing and accessible dental metallic restorations for calculation of intraoral currents. As regards the highest calculated intraoral current for each individual there was a statistically significant difference between the patient group and a control group consisting of 12 persons. An analysis of the amount of selenium, glutathione-peroxidase and mercury in the blood showed no differences between the patient and the control group. However, a statistically significant positive correlation could be seen between the total number of amalgam surfaces and the plasma-mercury level for patients and controls pooled together. The numerous other blood parameters analyzed did not reveal any differences between the groups.     

Student and faculty perceptions in the assessment of amalgam restorations

The purpose of this in-vitro study was to compare the assessment of amalgam restorations made by dental students and faculty members. Extracted human teeth which contained old amalgam restorations were mounted in dental stone and labeled one through 25. All evaluators were instructed the restorations were those of a 35-year-old patient with no clinical symptoms. The restorations were examined by 57 dental students and 10 dental instructors. Each examiner was asked to accept the restorations or replace the restorations with accompanying reason(s). Approximately one year after the first assessment, the blocks were randomly relabeled and all examiners reevaluated the amalgam restorations. the mean number of replacements, reasons for replacement, and kappa values were calculated for this study. A total of 1,675 decisions to replace or not to replace were obtained. There were a total of 2,784 reasons for replacement made by the students and 410 total decisions made by the dental faculty at the initial and final assessments. The study showed that dental faculty were more conservative in their treatment decisions. Also, the intraexaminer scores (kappa values) showed lower reproducibility among the dental students.     

Amalgam and composite posterior restorations: curriculum versus practice in operative dentistry at a US dental school

This study recorded the number of preclinical lecture and simulation laboratory sessions spent teaching the preparation and placement of amalgam and resin composite posterior restorations. These data were compared to the use of both materials in the operative clinic as placed by third- and fourth-year students. The number of posterior restorations inserted by the students, expressed as a function of the number of restoration surfaces, was also evaluated. The results show that the teaching of posterior restorations pre-clinically has consistently favored amalgam 2.5 to 1 during the last three years. However, clinically, resin composite is being used for posterior restorations 2.3 times more often than amalgam. The only instance that favored amalgam over composite during the last year was in the placement of four surface posterior restorations. This shift in emphasis from amalgam to composite needs to be addressed within dental educational institutions so that newly graduated dentists are prepared to place composite restorations properly.     

Teaching posterior composite resin restorations in the United Kingdom and Ireland: consensus views of teachers

Posterior composite resin restorations are an established feature of contemporary dental practice and all new dental graduates should be competent in providing such treatments for their patients. Surveys of educational curricula in this area in the United Kingdom and Ireland, as well as North America, have demonstrated variations both within and between dental schools. Such inconsistency does not help new dental school graduates, and may lead to confusion. At the British Association of Teachers of Conservative Dentistry Annual Conference held in Birmingham in September 2005, a session was devoted to the development of guidelines for dental schools on teaching posterior composite resin restorations to dental undergraduates. The theme of the conference concerned the teaching implications for changing from amalgam to composite. Two of the principal speakers at the meeting (Joost Roeters and Niek Opdam) were from the dental school at the University of Nijmegen in the Netherlands. This school was the first in Europe to discontinue the use of dental amalgam in its undergraduate curriculum over a decade ago. This paper reports the consensus views of those present on guidelines for teaching posterior composite resin restorations to dental undergraduate students.     

Reasons for restorative therapy and the longevity of restorations in adults

The aim of this study was to obtain information on the restorative dental care of adults in Finland. A random sample of private dentists was drawn from the register, and in spring 2000 they were sent a questionnaire requesting them to record information for each restoration placed during one ordinary working day. A total of 800 dentists were contacted and 548 responded. The dentists reported placement of 3,455 restorations. Of these, 5% were Class I, 36% were Class II, 13% were Class III, 9% were Class IV, 21% were Class V, and 16% were extensive restorations including 4 or more surfaces. Overall, composite resin was the most common restorative material, and it was used in 79% of the restorations, whereas amalgam was used in 5%, compomers in 4%, and glass ionomers (either conventional or resin‐modified) in 7% of cases. In 5% of the cases, the tooth was restored with indirect restorative methods, using either gold or ceramic materials. Of the treatments, 65% were replacements of previous restorations. Secondary caries was the most common reason for replacement (36%, 52%, and 41% for composite, glass ionomer, and amalgam, respectively). Other common reasons were fractures of the tooth or restoration (23%, 11%, and 22% for composite, glass ionomer, and amalgam, respectively) and lost composite restorations (16%). The median age of failed restorations was 15 years for amalgam, 6 years for composite, and 7 years for conventional glass ionomer. Although the longevity of tooth coloured restorations was shorter than that of amalgam, comparisons with our previous studies indicate improved survival periods for tooth coloured materials.     

Adhesive liner incorporation in dental amalgam restorations.

Previous studies have indicated that adhesive liners can affect the mechanical properties of set amalgam and, therefore, may become incorporated within the amalgam. The purpose of this in vitro study was to determine the distribution of two adhesive liners within standardized Class I amalgam restorations. Cavity preparations were restored with dental amalgam or with dental amalgam and either of two adhesive liners. Thin sections were cut from the restored teeth in various planes and examined radiographically and with a reflecting microscope. Radiographs were digitized and computer enhanced for improved observation. Amalgam restorations placed with adhesive liner had greater amounts of nonamalgam substance than did the nonadhesive liner restorations. Both Amalgambond Plus and Resinomer used with All-Bond II were capable of becoming incorporated within the body of a Class I restoration placed with a standard restorative amalgam bonding technique.     

A study design for an in vivo investigation of marginal fracture in amalgam restorations

A design for studying the modes of marginal fracture in amalgam restorations is presented. Amalgam restorations were placed in denture teeth mounted in tooth-supported partial dentures. Patients were recalled at selected intervals and the condition of the restorations was recorded with intraoral photographs and high-resolution impressions. Epoxy replicas were made from the impressions. At each recall, a percentage of the restorations were retrieved for analysis of the microstructure by SEM. The study design has two advantages over most clinical studies: the development of fractured areas was recorded in the series of replicas made prior to fracture; and changes in the subsurface microstructure that may lead to fracture can be followed in the series of restorations retrieved prior to fracture. Preliminary results of the study showed amalgam restorations in denture teeth to exhibit increasing marginal fracture with time in service. The morphology of the fractures appeared similar to that observed in restorations in natural human teeth.     

Class I and Class II silver amalgam and resin composite posterior restorations: teaching approaches in Canadian faculties of dentistry

A 10-question survey was mailed to the 10 Canadian faculties of dentistry to determine current approaches to teaching undergraduates about silver amalgam and resin composite for posterior restorations in adults and children. Responses were received from all 10 pedodontic programs and from 8 of the 10 operative and restorative programs. The use of silver amalgam and posterior composite for restorations of primary and permanent teeth is covered in the curricula of all dental schools, but the relative emphasis on the 2 materials varies. In the operative and restorative programs, curriculum time devoted to silver amalgam is either greater than or equal to that devoted to posterior composite. Five of the 8 schools reported greater educational emphasis on silver amalgam for the permanent dentition; however, course directors noted that the preference among patients seen in clinics is tending toward composite restorations. Curricula appear designed to educate students about the optimal use of both materials. Requirements for performance of restorations during training generally do not specify the type of material; these requirements range from 60 restorations to 250 surfaces. Five of the 8 schools conduct clinical competency tests with both materials. The responses from the pedodontic programs were more diverse. The proportion of curriculum time devoted to each type of material in these programs ranged from less than 25% to more than 75%. Five schools reported more emphasis on silver amalgam, 3 schools reported equal emphasis, and 2 schools reported more emphasis on posterior composite. No clinical requirements were specified in any of the undergraduate pedodontic programs. Within some of the faculties, there were differences between the operative and restorative program and the pedodontic program with respect to emphasis on different materials for the posterior dentition.     

Relationship between gap width and recurrent dental caries beneath occlusal margins of amalgam restorations

Abstract This study examines the relationship between gap width and the presence of recurrent dental caries subjacent to occlusal margins of amalgam restorations. The study population consisted of 35 adult patients of the university's dental clinic who were having occlusal amalgam restorations removed solely because of defective margins. In this group, an impression was made recording the width of a clinically detected gap between the amalgam restoration and the adjacent enamel cavosurface. Of this study population, 20 teeth with recurrent caries were identified from 18 subjects after restoration removal. Upon removal of the restoration, the presence and location of recurrent dental caries associated with a margin was noted. The mean gap widths of recurrent carious sites and non-carious sites were compared in the same tooth. A difference of 187 μm was found between the mean gap width of the recurrent caries sites and the non-carious sites, with the recurrent caries gaps being wider. A paired t-test based on the differences was calculated (P < 0.0001). The results suggest that there is a direct association between gap width and recurrent caries in occlusal margins of amalgam restorations.