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The Cochrane Database of Systematic... Aug 2021Traditionally, amalgam has been used for filling cavities in posterior teeth, and it continues to be the restorative material of choice in some low- and middle-income... (Review)
Review
BACKGROUND
Traditionally, amalgam has been used for filling cavities in posterior teeth, and it continues to be the restorative material of choice in some low- and middle-income countries due to its effectiveness and relatively low cost. However, there are concerns over the use of amalgam restorations (fillings) with regard to mercury release in the body and the environmental impact of mercury disposal. Dental composite resin materials are an aesthetic alternative to amalgam, and their mechanical properties have developed sufficiently to make them suitable for restoring posterior teeth. Nevertheless, composite resin materials may have potential for toxicity to human health and the environment. The United Nations Environment Programme has established the Minamata Convention on Mercury, which is an international treaty that aims "to protect the [sic] human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds". It entered into force in August 2017, and as of February 2021 had been ratified by 127 governments. Ratification involves committing to the adoption of at least two of nine proposed measures to phase down the use of mercury, including amalgam in dentistry. In light of this, we have updated a review originally published in 2014, expanding the scope of the review by undertaking an additional search for harms outcomes. Our review synthesises the results of studies that evaluate the long-term effectiveness and safety of amalgam versus composite resin restorations, and evaluates the level of certainty we can have in that evidence.
OBJECTIVES
To examine the effects (i.e. efficacy and safety) of direct composite resin fillings versus amalgam fillings.
SEARCH METHODS
An information specialist searched five bibliographic databases up to 16 February 2021 and used additional search methods to identify published, unpublished and ongoing studies SELECTION CRITERIA: To assess efficacy, we included randomised controlled trials (RCTs) comparing dental composite resin with amalgam restorations in permanent posterior teeth that assessed restoration failure or survival at follow-up of at least three years. To assess safety, we sought non-randomised studies in addition to RCTs that directly compared composite resin and amalgam restorative materials and measured toxicity, sensitivity, allergy, or injury.
DATA COLLECTION AND ANALYSIS
We used standard methodological procedures expected by Cochrane.
MAIN RESULTS
We included a total of eight studies in this updated review, all of which were RCTs. Two studies used a parallel-group design, and six used a split-mouth design. We judged all of the included studies to be at high risk of bias due to lack of blinding and issues related to unit of analysis. We identified one new trial since the previous version of this review (2014), as well as eight additional papers that assessed safety, all of which related to the two parallel-group studies that were already included in the review. For our primary meta-analyses, we combined data from the two parallel-group trials, which involved 1645 composite restorations and 1365 amalgam restorations in 921 children. We found low-certainty evidence that composite resin restorations had almost double the risk of failure compared to amalgam restorations (risk ratio (RR) 1.89, 95% confidence interval (CI) 1.52 to 2.35; P < 0.001), and were at much higher risk of secondary caries (RR 2.14, 95% CI 1.67 to 2.74; P < 0.001). We found low-certainty evidence that composite resin restorations were not more likely to result in restoration fracture (RR 0.87, 95% CI 0.46 to 1.64; P = 0.66). Six trials used a split-mouth design. We considered these studies separately, as their reliability was compromised due to poor reporting, unit of analysis errors, and variability in methods and findings. Subgroup analysis showed that the findings were consistent with the results of the parallel-group studies. Three trials investigated possible harms of dental restorations. Higher urinary mercury levels were reported amongst children with amalgam restorations in two trials, but the levels were lower than what is known to be toxic. Some differences between amalgam and composite resin groups were observed on certain measures of renal, neuropsychological, and psychosocial function, physical development, and postoperative sensitivity; however, no consistent or clinically important harms were found. We considered that the vast number of comparisons made false-positive results likely. There was no evidence of differences between the amalgam and composite resin groups in neurological symptoms, immune function, and urinary porphyrin excretion. The evidence is of very low certainty, with most harms outcomes reported in only one trial.
AUTHORS' CONCLUSIONS
Low-certainty evidence suggests that composite resin restorations may have almost double the failure rate of amalgam restorations. The risk of restoration fracture does not seem to be higher with composite resin restorations, but there is a much higher risk of developing secondary caries. Very low-certainty evidence suggests that there may be no clinically important differences in the safety profile of amalgam compared with composite resin dental restorations. This review supports the utility of amalgam restorations, and the results may be particularly useful in parts of the world where amalgam is still the material of choice to restore posterior teeth with proximal caries. Of note, however, is that composite resin materials have undergone important improvements in the years since the trials informing the primary analyses for this review were conducted. The global phase-down of dental amalgam via the Minamata Convention on Mercury is an important consideration when deciding between amalgam and composite resin dental materials. The choice of which dental material to use will depend on shared decision-making between dental providers and patients in the clinic setting, and local directives and protocols.
Topics: Bias; Child; Composite Resins; Dental Amalgam; Dental Caries; Dentition, Permanent; Humans; Randomized Controlled Trials as Topic
PubMed: 34387873
DOI: 10.1002/14651858.CD005620.pub3 -
Oral Health & Preventive Dentistry Mar 2022The Minamata Convention resulted in restrictions in the use of amalgam in daily dental practice. This opens up new discussions about the biocompatibility of amalgam, but... (Review)
Review
The Minamata Convention resulted in restrictions in the use of amalgam in daily dental practice. This opens up new discussions about the biocompatibility of amalgam, but also of composites as alternative materials. In the following review article, these issues will be discussed in more detail to provide dentists with a knowledge base for themselves and for communication with their patients. In addition to mercury in amalgam or monomers in composites, bisphenol A and nanoparticles generated during the grinding, polishing or removal of restorations must also be included in the biocompatibility evaluation. In laboratory tests, these substances cause toxic reactions, and bisphenol A also exhibits estrogen-like effects. However, it must be taken into account that the concentrations used in laboratory tests are much higher than in clinical practice. Thus, both amalgam and composite can be used in the general population. Nevertheless, for scientifically, politically and legally defined risk groups (e.g. dental personnel, allergic persons, pregnant or lactating women, children under 15 years of age, people with certain systemic diseases), indication restrictions and precautionary measures must be observed. The well-known amalgam discussion has taught us the importance of thorough and open risk communication with the patient.
Topics: Benzhydryl Compounds; Biocompatible Materials; Dental Amalgam; Humans; Mercury; Nanoparticles; Phenols; Risk Factors
PubMed: 35308016
DOI: 10.3290/j.ohpd.b2831749 -
Journal of Dentistry Sep 2015The aim of the present review was to evaluate by means of a systematic review and meta-analysis the hypothesis of no difference in failure rates between amalgam and... (Comparative Study)
Comparative Study Meta-Analysis Review
OBJECTIVES
The aim of the present review was to evaluate by means of a systematic review and meta-analysis the hypothesis of no difference in failure rates between amalgam and composite resin posterior restorations.
DATA
Randomized controlled trials, controlled clinical trials and prospective and retrospective cohort studies were included in this review. The eligibility criteria included clinical trials in humans with at least 12 months of follow-up comparing the failures rates between occlusal and occlusoproximal amalgam and composite resin restorations. Clinical questions were formulated and organized according to the PICOS strategy.
SOURCE
An electronic search without restriction on the dates or languages was performed in PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science up until March 2015.
STUDY SELECTION
The initial search resulted in 938 articles from PubMed/MEDLINE, 89 titles from the Cochrane Central Register of Controlled Trials, and 172 from the Web of Science. After an initial assessment and careful reading, 8 studies published between 1992 and 2013 were included in this review. According to the risk of bias evaluation, all studies were classified as high quality.
CONCLUSIONS
The results of this review suggest that composite resin restorations in posterior teeth still have less longevity and a higher number of secondary caries when compared to amalgam restorations. In relation to fractures, there was no statistically significant difference between the two restorative materials regarding the time of follow-up.
CLINICAL SIGNIFICANCE
There is currently a worldwide trend towards replacing amalgam restorations with mercury-free materials, which are adhesive and promote aesthetics. It is important to perform an updated periodic review to synthesize the clinical performance of restorations in the long-term.
Topics: Acrylic Resins; Composite Resins; Dental Amalgam; Dental Restoration Failure; Humans; Polyurethanes
PubMed: 26116767
DOI: 10.1016/j.jdent.2015.06.005 -
International Journal of Environmental... Mar 2019Mercury (Hg) has been identified as one of the most toxic nonradioactive materials known to man. Although mercury is a naturally occurring element, anthropogenic mercury... (Review)
Review
Mercury (Hg) has been identified as one of the most toxic nonradioactive materials known to man. Although mercury is a naturally occurring element, anthropogenic mercury is now a major worldwide concern and is an international priority toxic pollutant. It also comprises one of the primary constituents of dental amalgam fillings. Even though dental mercury amalgams have been used for almost two centuries, its safety has never been tested or proven in the United States by any regulatory agency. There has been an ongoing debate regarding the safety of its use since 1845, and many studies conclude that its use exposes patients to troublesome toxicity. In this review, we present in an objective way the danger of dental amalgam to human health based on current knowledge. This dilemma is addressed in terms of an integrated toxicological approach by focusing on four mayor issues to show how these interrelate to create the whole picture: (1) the irrefutable constant release of mercury vapor from dental amalgams which is responsible for individual chronic exposure, (2) the evidence of organic mercury formation from dental amalgam in the oral cavity, (3) the effect of mercury exposure on gene regulation in human cells which supports the intrinsic genetic susceptibility to toxicant and, finally, (4) the availability of recent epidemiological data supporting the link of dental amalgams to diseases such as Alzheimer's and Parkinson.
Topics: Dental Amalgam; Humans; Mercury; United States
PubMed: 30909378
DOI: 10.3390/ijerph16061036 -
The European Journal of Prosthodontics... Nov 2022The objective of this systematic review was to compare the longevity of direct amalgam and composite resin restorations, in posterior teeth, through clinical,...
OBJECTIVES
The objective of this systematic review was to compare the longevity of direct amalgam and composite resin restorations, in posterior teeth, through clinical, prospective or retrospective studies, with at least 5 years of follow-up.
MATERIALS AND METHODS
Studies published in the last 15 years (from 2006 to 2021) were collected using the PubMed and Medline databases.
RESULTS
The search strategy associated with the established inclusion and exclusion criteria resulted in a total of 17 articles. Factors related to failures in the performance of restorations were analyzed together with the clinical performance results of each material over the years of study, according to the methodology of each article.
CONCLUSIONS
Regardless of the restorative material, the successful results over more than 5 years are due much more to the correct application of the technique, the operator's skill/knowledge and factors related to the patient, such as the type of tooth, number of faces involved in the restoration and oral hygiene.
Topics: Humans; Prospective Studies; Retrospective Studies; Composite Resins; Dental Materials
PubMed: 35438266
DOI: 10.1922/EJPRD_2371Maciel09 -
Journal of Endodontics Dec 2014Clinicians routinely face conditions in which they have to decide whether the dental pulp can be saved or not. This study evaluated how reliable the clinical diagnosis... (Comparative Study)
Comparative Study
INTRODUCTION
Clinicians routinely face conditions in which they have to decide whether the dental pulp can be saved or not. This study evaluated how reliable the clinical diagnosis of normal pulp/reversible pulpitis (savable pulp) or irreversible pulpitis (nonsavable pulp) is when compared with the histologic diagnosis.
METHODS
The study material consisted of 95 teeth collected consecutively in a general practice over a 5-year period and extracted for reasons not related to this study. Based on clinical criteria, teeth were categorized as having normal pulps, reversible pulpitis, or irreversible pulpitis. The former 2 were grouped together because they represent similar conditions in terms of prognosis. Teeth were processed for histologic and histobacteriologic analyses, and pulps were categorized as healthy, reversibly inflamed, or irreversibly inflamed according to defined criteria. The number of matching clinical/histologic diagnosis was recorded.
RESULTS
The clinical diagnosis of normal pulp/reversible pulpitis matched the histologic diagnosis in 57 of 59 (96.6%) teeth. Correspondence of the clinical and histologic diagnosis of irreversible pulpitis occurred in 27 of 32 (84.4%) cases. Infection advancing to the pulp tissue was a common finding in teeth with irreversible pulpitis but was never observed in normal/reversibly inflamed pulps.
CONCLUSIONS
Findings using defined criteria for clinical and histologic classification of pulp conditions revealed a good agreement, especially for cases with no disease or reversible disease. This means that the classification of pulp conditions as normal pulps, reversible pulpitis, and irreversible pulpitis has high chances of guiding the correct therapy in the large majority of cases. However, there is still a need for refined and improved means for reliable pulp diagnosis.
Topics: Adolescent; Adult; Aged; Bacteria; Composite Resins; Dental Amalgam; Dental Caries; Dental Materials; Dental Pulp; Dental Pulp Necrosis; Dental Pulp Test; Dental Restoration, Permanent; Dentin; Dentin, Secondary; Diagnosis, Differential; Female; Humans; Male; Middle Aged; Odontoblasts; Prognosis; Pulpitis; Young Adult
PubMed: 25312886
DOI: 10.1016/j.joen.2014.08.010 -
British Dental Journal May 2022With the phasing down of dental amalgam use in response to the Minamata Convention, it is likely that resin-based composite restoratives will be the dental material of... (Review)
Review
With the phasing down of dental amalgam use in response to the Minamata Convention, it is likely that resin-based composite restoratives will be the dental material of choice for the direct restoration of compromised dentition in the UK, at least for the foreseeable future. The current materials have a finite lifespan, with failures predominately due to either secondary caries or fracture. Consequently, there is considerable in vitro research reported each year with the intention of producing improved materials. This review describes the recent research in materials designed to have low polymerisation shrinkage and increased mechanical properties. Also described is research into materials that are either antimicrobial or are designed to release ions into the surrounding oral environment, with the aim of stimulating remineralisation of the surrounding dental tissues. It is hoped that by describing this recent research, clinicians will be able to gain some understanding of the current research that will potentially lead to new products that they can use to improve patient treatment in the future.
Topics: Composite Resins; Dental Amalgam; Dental Caries; Dental Materials; Dental Restoration, Permanent; Humans
PubMed: 35562465
DOI: 10.1038/s41415-022-4240-8 -
British Dental Journal Nov 2022Phase out of dental amalgam requires investment in prevention measures, research and development of alternative materials, and effective waste management processes. The...
Phase out of dental amalgam requires investment in prevention measures, research and development of alternative materials, and effective waste management processes. The dental profession is supporting the phase-down of dental amalgam but dentists need the full armoury of dental materials and must be trusted to share decision-making with their patients about clinical choices. Unintended consequences of a rapid global phase-out of dental amalgam must be properly understood before it is universally imposed.
Topics: Dental Amalgam; Dental Restoration, Permanent; Mercury
PubMed: 36434231
DOI: 10.1038/s41415-022-5217-3 -
British Dental Journal Nov 2023
Topics: Dental Amalgam; Dental Restoration, Permanent
PubMed: 38001180
DOI: 10.1038/s41415-023-6572-4 -
Journal of Health & Pollution Jun 2019Mercury in dental amalgam is a hidden source of global mercury pollution, resulting from the illegal diversion of dental mercury into the artisanal and small-scale gold... (Review)
Review
BACKGROUND
Mercury in dental amalgam is a hidden source of global mercury pollution, resulting from the illegal diversion of dental mercury into the artisanal and small-scale gold mining sector, to crematoria emissions from the deceased and sewage sludge that is sold to farmers. These significant mercury sources result in air, water, and food contamination that consequently have a negative impact on human health.
OBJECTIVES
The aim of the present study was to investigate and report on all of the various pathways mercury in dental amalgam can enter the environment.
METHODS
The present study searched the electronic data bases of PubMed and Google Scholar. Peer reviewed journals and references of studies included for full-text review were examined for potentially relevant studies. Articles published between 2000 to 2018 were searched and specifically screened for articles that referenced "Dental Amalgam," and the following key words in various combinations: "Minamata Convention on Mercury Treaty," "Sewage Sludge," "Cremation," and "Artisanal and Small-Scale Gold Mining." Data were included on the most populous countries of China, India, the United States, Brazil, and the European Union collectively. We also included data on cremation statistics and current global trends, looking at populations where cremation is a common practice, such as Japan and India.
DISCUSSION
Dental amalgam represents a significant, but understudied area of global mercury pollution that includes cremation, sewage sludge, burial, and small-scale gold mining.
CONCLUSIONS
Mercury used in products and processes, including dental amalgams, is a global pollutant. Even after the last mercury dental amalgam is placed, its toxic legacy will continue for decades, because of its pervasive bioaccumulation in the environment. Government regulatory agencies should make it mandatory to utilize available technologies, not only in developing countries, but also in developed countries, to reduce mercury contamination.
COMPETING INTERESTS
The authors declare no competing financial interests.
PubMed: 31259088
DOI: 10.5696/2156-9614-9.22.190612