Alternatives to silver amalgam and resin composite in pediatric dentistry.

Silver amalgam has become a less attractive dental restorative material for restoration of primary teeth. After many decades of scientific and nonscientific controversy, use of silver amalgam for primary teeth is waning, not because of its mercury content but because dentistry has come up with more suitable materials. This article reviews the development and use of glass-ionomer silver-cermet cements, resin-modified glass-ionomer cements, and polyacid-modified resin composites (compomers) for restoration of primary teeth.     

Clinical performance and caries inhibition of resin-modified glass ionomer cement and amalgam restorations

BACKGROUND: The authors clinically examined two restorative materials to evaluate their effectiveness in Class II restorations in primary molars and their ability to inhibit recurrent caries. METHODS: Forty subjects, each in need of two Class II restorations in primary molars, took part in this study. Each patient received one Class II restoration of resin-modified glass ionomer cement and one of amalgam. The authors evaluated the restorations at six-month, one-year, two-year and three-year recall appointments. On exfoliation, teeth with experimental restorations were retrieved and microscopically examined for inhibition of demineralization at restoration margins. RESULTS: The results of the clinical evaluation demonstrated no significant differences between the resin-modified glass ionomer cement restorations and the amalgam restorations (P < .05). Polarized light microscopic examination of the returned teeth that were restored as a part of this study indicated that the resin-modified glass ionomer cement had significantly less enamel demineralization at restoration margins than did amalgam (P < .0001). CONCLUSIONS: The resin-modified glass ionomer cement functioned clinically as well as amalgam for Class II restorations in primary molars. However, the resin-modified glass ionomer exhibited significantly less enamel demineralization at restoration margins than did amalgam. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement restorative material functions well for Class II restorations in primary molars and exhibits less recurrent caries at restoration margins than does amalgam.     

Microleakage between endodontic temporary restorative materials placed at different times.

Occlusal endodontic access preparations are occasionally made in teeth without removing the original restoration. However, microleakage between restorative materials that are placed at different times has not been extensively studied. Therefore, our objective was to compare microleakage at three areas: between an access opening restorative material and the cavity wall; between an additional material placed later to patch a secondary opening in the first restorative material and the original restorative material itself; and between the secondarily placed material and the cavity wall. Standard endodontic access preparations were made in 120 noncarious, nonrestored crowns of extracted human molars. These teeth were divided into six experimental groups. Another four molars were controls. The endodontic access cavities were restored with either IRM or amalgam as the primary restorative material. After 14 days, half of the primary restorations was removed, and this defect was filled with a secondary restorative material: IRM, Caviton, or a double seal of Caviton and IRM. Microleakage was measured linearly as the extent of basic fuchsin dye penetration under a stereomicroscope after thermal cycling (5 degrees and 55 degrees C for 100 cycles) and tooth sectioning. Wilcoxon signed-rank test was used for statistical analysis. Results indicated significantly less microleakage between primary and secondary restorative materials placed at different times than microleakage between primary temporary restorative materials and the access cavity wall, regardless of the type of primary restorative material used (IRM or amalgam).     

Direct placement restorative materials for use in posterior teeth: the current options

The purpose of this paper is to provide guidelines to assist in the selection of dental materials for restoring posterior teeth in adolescents. Currently, amalgam is still the best plastic restorative material for some Class I cavities, and for Class II cavities and all multi-surface restorations. Tooth-coloured materials are preferred by some patients and dentists, however these alternatives are more technique sensitive than amalgam. Composite resin is the most common direct placement alternative to dental amalgam, providing patients with relatively low cost, tooth-coloured restorations. However, composite resins have limited indication, their placement is more time-consuming than for amalgam, cost-benefit considerations are a concern, difficulty in obtaining a marginal seal persists and there are few long-term studies published in the peer reviewed scientific literature. The literature currently supports the use of composite resin for the restoration of a limited range of Class I and Class II cavities. Composite resin restorations are not recommended for MOD or other multi-surface restorations. In selected clinical situations, fissure sealants, preventive resin restorations and glass ionomer cement are also appropriate materials to use to restore posterior teeth. Fissure sealants, when properly maintained, can play a significant role in the prevention and control of dental caries in pits and fissures in primary and permanent teeth. Preventive resin restorations should be placed to restore deep pits and fissures with incipient caries and/or developmental defects in primary and permanent teeth. Glass ionomer cement may be used for restoring Class V cavities where appearance is not the primary concern, for conservative Class III cavities, and as a provisional restorative material. It is not recommended for Class II or IV restorations.     

Composite or amalgam? Not a black or white decision

Amalgam as a restorative material in dentistry is discussed because of believed toxic properties of the material, yet there is no scientific prove for the assumption. Adhesive restorations are a possible alternative for amalgam in restoring posterior teeth. For treatment of primary caries, the direct composite resin restoration has many advantages. When greater defects are to be restored, adhesive composite resin restorations become less favourable. At this moment no long term results are available for indirect adhesive techniques. For the time being it seems necessary to use composite resin as well as amalgam for the restoration of posterior teeth.     

Filling cavities or restoring teeth?

Teeth seldom fracture under normal functional loading. This indicates that the natural tooth design is optimized for the distribution of regular masticatory forces by means of its properties and structure. When a tooth is restored with an intracoronal restoration, however, the incidence of tooth fracture increases. Since remaining tissues do not change, the restorative actions apparently alter the original stress distributions. In this study, the effect of different restoration types (unbonded amalgam and bonded composite restorations) were compared with the original stress conditions of the intact tooth, using finite element analysis. It was shown that an unbonded amalgam restoration did not restore the original stress conditions but led to much higher stresses in the buccal and lingual enamel and to higher tensile stresses in the cavity floor. The unbonded amalgam thus filled the cavity but did not restore the tooth. In contrast, a bonded composite restoration restored the original stress pattern in the tooth if there was no polymerization shrinkage. Polymerization shrinkage causes residual tensile stresses in the dentin around the cavity and in the buccal and lingual enamel. Residual tensile stresses in the buccal and lingual enamel are momentary compensated by compressive stress components during occlusal loading. It was concluded that bonding and elimination of residual stresses are prerequisites for restoring the original tooth integrity.     

Class II amalgam restorations, glass-ionomer tunnel restorations, and caries development on adjacent tooth surfaces: a 3-year clinical study.

Eighteen caries-active adolescents, each having both a class II conventional amalgam (Dispersalloy) and a glass-ionomer (Ketac Silver) tunnel restoration of the same age placed on a contralateral tooth, were part of a 3-year clinical study. At the 1- and 2-year examinations all test restorations were assessed as acceptable in all patients. At the 3-year assessment three amalgam restorations failed due to recurrent caries, and one glass-ionomer restoration failed due to marginal ridge fracture. During the entire study period, the requirement of restorative therapy because of primary proximal caries was significantly reduced (p < 0.05) on tooth surfaces adjacent to the glass-ionomer restorations as compared with that on tooth surfaces adjacent to the amalgam restorations.     

Materials used to restore class II lesions in primary molars: a survey of California pediatric dentists

PURPOSE: The purpose of this study was to determine which materials were most commonly used by pediatric dentists in California to restore Class II lesions in the primary dentition. METHODS: A questionnaire consisting of 18 multiple-choice questions was mailed to all 440 active members of the California Society of Pediatric Dentistry (CSPD). The questions related to the practitioners' material of choice for restoring Class II lesions in primary molars. RESULTS: A 66% response rate was received. For 57% of the respondents, amalgam was the material of choice for restoration of Class II lesions in primary molars. Twenty-nine percent selected composite, 5% glass ionomer, 6% compomer, and 1% (1 practitioner) stainless steel crowns. Sixty-eight percent responded that amalgam has historically proven to be a safe, reliable, and affordable material. The main reasons cited for using composite resin were "patient preference" (86%) and "better esthetics" (78%). Most practitioners used either a single-step (fifth-generation) or 2-step (fourth-generation) bonding agent (53% and 35%, respectively). When using a nonamalgam restorative material, 49% of practitioners used a traditional Class II amalgam preparation. The role of dental literature in treatment decision-making was not significantly related to the restorative material used. CONCLUSIONS: While amalgam was the most common material used for Class II restorations, nonamalgam materials were significantly popular among California pediatric dentists.     

Local adverse effects of amalgam restorations

Amalgam has been used for the restoration of teeth for well over 100 years, and is the most successful of the direct restorative materials with respect to longevity. Despite the increasing use of tooth-coloured materials, with advantages of aesthetics and adhesion, amalgam is one of the most widely used dental restorative materials. One of the principal disadvantages of amalgam, apart from aesthetics, is that it may have adverse biological effects, both locally and systemically. Locally, it can cause an erythematous lesion on the adjacent oral soft tissues (tongue and buccal mucosa), and systemically free mercury in the amalgam may give rise to a hypersensitivity reaction. The purpose of this paper is to review the literature concerning the local adverse reactions to dental amalgam. The focus will be on the reactions of the oral mucosa, and brief consideration will be given to laboratory cytotoxicity of dental amalgam and its components, and to the 'amalgam tattoo'.     

The post-amalgam era: a selection of materials and their longevity in the primary and young permanent dentitions

Summary. Objectives. During the last decade there has been a rapid change in the selection of dental restorative materials as the use of amalgam has decreased. The aim of this study was to obtain information on children's restorative dental care in Finland and to analyse the longevity of failed restorations. Design. A random sample of public dental health care centres was drawn from the registers and the dentists working there were asked to record information for each restoration they placed during a three‐day period. The survey data comprised a total of 2186 restorations in patients younger than 17 years. Results. Of the children in need of restorative treatment, only a few had previous amalgam restorations. Primary caries was the main reason for restorative treatment in both primary and permanent dentitions (80% and 83%, respectively). In primary teeth, the most common restorative material was resin‐modified glass ionomer cement (57·4%), whereas in permanent teeth, composite resin dominated (58·7%). Amalgam was not used at all in the primary dentition and in only 0·6% of permanent teeth. Eighteen per cent of treatments in primary and 12% in permanent teeth were replacements of previous fillings. The mean age of failed glass ionomer restorations was 2·8 years (n = 101) in the primary dentition, and 3·5 years (n = 54) in the permanent dentition. Conclusions. Until better restorative materials are developed, more attention should be paid to the prevention of dental caries as well as to the proper handling of alternative materials.     

牙体修复失败原因探讨

目的 通过对256颗牙体修复失败原因分析，探讨提高牙体修复质量的各种相关因素。方法 收集因牙体修复失败需重新治疗235位患者的256颗牙齿，其中银汞修复146颗牙;高分子材料修复110颗牙。分别对其修复失败原因和修复体在口腔中存在时间长短，进行总结分析。结果 无论用银汞合金，还是高分子材料修复，失败比例最高为继发龋，分别占28．76％和23．64％；其次，银汞合金为牙折、洞型设计不良、根尖炎、He创伤、修复体脱落、修复体折断、牙髓炎、食物嵌塞和悬突。高分子材料为色素沉积、He创伤、修复体折断、修复体脱落、牙髓炎、修复体磨损、根尖炎、悬突和食物嵌塞。分析修复体存在口腔中存留的时间发现，银汞合金和高分子材料修复中，1～3年组失败最高，分别占44．52％和32．73％。结论 在牙体修复中，预防继发龋的发生，调整咬合关系，对延长修复体的使用寿命是至关重要的。     

A comparative life cycle assessment of dental restorative materials

ObjectivesDifferent types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation is to determine, through a comparative cradle-to-gate life cycle assessment, the environmental impacts of three direct-placement dental restorative materials (DRMs) and their associated packaging.MethodsThree direct-placement dental materials; dental amalgam, resin-based composite (RBC) and glass polyalkenoate cements (GIC) are assessed using primary data from a manufacturer (SDI Limited, Australia). The functional unit consisted of ‘one dental restoration’ of each restorative system under investigation: 1.14 g of dental amalgam; 0.25 g of RBC (plus the adhesive = 0.10 g); and 0.54 g of GIC. The system boundary per restoration included the raw materials and their associated packaging materials for each DRM together with the processing steps for both the materials and packaging. The environmental impacts were assessed using an Egalitarian approach under the ReCiPe method using Umberto software and the Ecoinvent database. Nine different impact categories were used to compare the environmental performance of these materials.ResultsDental amalgam had the highest impact across most of the categories, but RBC had the highest Global Warming Potential. The highest sources of the environmental impacts for each restorative material were: Amalgam, derived from material use; RBC, derived from energy use in processing material and packaging material; GIC, derived from material and energy use for packaging.SignificanceLess intensive energy sources or more sustainable packaging materials can potentially reduce the impacts associated with RBC and GIC thus making them suitable alternatives to dental amalgam.     

Trends in the selection of dental filling materials.

In 1983 and 1988 a questionnaire was sent to a random sample of Belgian dentists to compare the selection of filling materials such as amalgam and gold with the tooth-coloured filling materials, composites and glass polyalkenoate (ionomer) cements, for the restoration of Class II lesions in premolar and permanent molar teeth. Despite the increasing demand for aesthetics to be considered, the use of composite resins in the posterior region only increased moderately over the assessment period, while amalgam maintained its leading position as the restorative material of choice in premolar and molar teeth. Only in situations where aesthetics played a primary role did composite resins gain over silver-based fillings. There was no change in the use of gold as an indirect restorative material. Finally, the selection rate of glass ionomers increased slightly.     

Placement and replacement of restorations in primary teeth

This practice-based study aimed to record the use of restorative materials, the type of restoration by class, and the reason for and the age of failed restorations in primary teeth by means of a survey of placement and replacement of restorations in 1996 and 2000/2001. Written alternative criteria for placement and replacement of restorations were provided for the participating clinicians. Details on 2281 restorations showed that primary caries was the main reason for inserting restorations in primary teeth. Replacements of failed restorations represented 14% of the fillings (n = 2040) in 1996 and 9% in 2000/2001 (n = 241). More than 80% or the fillings in primary teeth were of tooth-colored material, predominantly of the light-cured type. About 50% of failed amalgam and glass ionomer-type restorations were replaced due to secondary caries. The median age of amalgam restorations (3 years) was significantly higher than that of tooth-colored restorations (2 years). Any possible advantage of a cariostatic effect of glass ionomer-type materials is apparently annulled by their short longevity compared with amalgam.     

Stiffness of endodontically-treated teeth related to restoration technique

Endodontically-treated posterior teeth are susceptible to fracture; consequently, full-occlusal-coverage restorations are recommended. We designed this study to examine the potential for alternative restorative techniques for pulpless teeth, using strain gauges mounted on extracted maxillary second premolars to measure strains generated by nondestructive occlusal loading. Cuspal stiffness was evaluated on the following sequentially performed procedures: unaltered tooth, completion of all endodontic procedures, appropriate restorative preparation, and restoration. The restorative procedures evaluated were: (1) amalgam, (2) cast gold onlay, (3) composite restoration with enamel etch, and (4) composite restoration with enamel and dentin etch. Finally, all teeth were loaded to fracture. Cast gold was the strongest restorative material tested (2.11 relative stiffness, compared with that of the unaltered tooth at 1.00), and amalgam was the weakest (0.35 relative stiffness). Composite restoration and enamel plus dentin etch were almost as strong as the unaltered tooth (0.87 relative stiffness), while enamel-etch-only yielded lower stiffness (0.51).     

Long-term deterioration of composite resin and amalgam restorations.

Previous long-term longitudinal studies of two different methods of placing an auto-cured conventional anterior composite resin, and of a low- and a high-copper amalgam alloy, had shown similar restoration survivals despite the different resin treatment methods used or the types of amalgam alloy placed. Therefore, the aim of the present study was to assess several clinical factors or characteristics of these restorations that were believed to affect the survival of the restorative materials. The 950 composite resin and the 1042 amalgam restorations examined were placed by many operators in numerous patients attending a dental hospital. The composite resin restorations were placed using unetched- and etched-enamel-bonding treatment methods, and the amalgam restorations were polished after insertion. Clinical ratings supplemented by color transparencies were used for the assessment of four factors for the resin, and four factors for the amalgam restoration. Significant deterioration differences were found for several of the clinical factors assessed for both the two different composite resin treatment methods, and for the two different amalgam alloys, which were not directly related to the restoration survivals.     

Fracture resistance of Class II approximal slot restorations

STATEMENT OF PROBLEM: Determination of the fracture resistance of various restorative materials in Class II approximal slot restorations has not been studied. PURPOSE: This study evaluated the effects of retention grooves and different restorative materials in Class II approximal slot restorations. To explore the possibilities for further research, the probable effects of preparation size and loading angle were investigated in a limited manner. MATERIAL AND METHODS: Ninety sound, caries-free human maxillary premolars were divided into 9 groups. The cavities were prepared either by hand or in a computer-controlled CNC machine with or without retention grooves. Four were restored with adhesive amalgam, another 4 with composite, and a single group with Compomer resin. The gingival floor depth was 1.5 mm. The specimens were loaded at an angle of 13. 5 degrees to their longitudinal axes by using a computer-controlled material testing machine until failure occurred. For one specific preparation of adhesive amalgam, loading was applied at 0 and 30 degrees to determine the probable effects of the loading angle. For a specific composite, resin application, the effects of the change in gingival floor depth were analyzed by assigning the depth to 2.0 mm. RESULTS: Composite and Compomer resin and composite exhibited better performance than amalgam. The existence of the retention grooves proved to be effective for adhesive amalgam restorations but did not have any advantageous effect in composite and Compomer restoration. CONCLUSION: For improved fracture resistance in small approximal restorations, the use of composite was the appropriate choice. Compomer also gave satisfactory results. Use of amalgam restoration should be accompanied with retention grooves and an adhesive system to improve its performance.     

非创伤性充填技术治疗乳磨牙龋疗效观察

目的探讨非创伤性充填技术(ART)修复乳牙龋的疗效及儿童对ART的接受程度。方法选择患牙本质龋的乳牙580颗,分为3组,ART充填198颗,190颗牙作为对照进行银汞合金充填,192颗采用牙钻备洞,玻璃离子充填。1年及2年后复查。结果84.5%儿童使用ART治疗无不适感,91.2%的学生愿意使用ART方法进行治疗。ART组第1、2年的成功率(88.3%、76.0%)与银汞合金对照组(80.5%、71.3%)、牙钻玻璃离子组(89.9%,79.9%)无显著性差异。ART组及牙钻组2年继发龋发生率(10.55%与9.80%)低于银汞合金对照组(22.56%),差异有显著性。结论ART技术简单,效果较好,对于乳牙龋是一种有效的治疗方法。     

Functional and aesthetic guidelines for stress-reduced direct posterior composite restorations

Amalgam has been used in the restoration of structurally compromised posterior teeth for many years. When placing large amalgam restorations, replacement of weak cusps with restorative material is recommended to prevent tooth fracture. This recommendation can be modified with new guidelines using modern adhesive techniques. Semidirect and indirect inlay/onlay composite restorations have progressively replaced amalgam restorations over the past 20 years. Lately, single visit direct resin-bonded composite (RBC) restorations have also been used as a viable alternative to conventional indirect restorations. This paper is intended to introduce a step-by-step protocol for the direct restoration of structurally compromised posterior teeth using RBCs with stress-reducing protocols.     

Dentists' restorative decision‐making and implications for an ‘amalgamless’ profession. Part 1: a review

The Minamata Convention has agreed to a worldwide reduction and ultimate elimination in the production and use of mercury containing products. This will have implications for the practice of dentistry. Australian organizations' pronouncements on the issue are limited and research examining the Australian context dated. The restoration of teeth with direct materials has changed significantly since the 1980s. Up to this time amalgam was the material of choice for direct posterior restorations. Its properties and guidelines for placement were, and remain, well established. Resin composite has replaced amalgam as the material of choice in many clinical situations. Despite inherent clinical disadvantages compared to amalgam, there continues to be a shift toward greater use of resin composite. There is consensus worldwide that the restoration of posterior teeth using resin composite now exceeds that of amalgam. The reasons for this are reviewed in this article along with current evidence and commentary relating to direct restorative and evidence‐based decision‐making, minimally invasive approaches, and approaches to education. The implications for these in an ‘amalgamless’ profession are identified.