Longevity of extensive class II open-sandwich restorations with a resin-modified glass-ionomer cement.

Several new techniques have been introduced for use in the esthetic restoration of posterior cavities to substitute for the presumed toxicity of amalgam. Composite-laminated glass-ionomer cement restorations, the sandwich technique, have been recommended for caries-risk patients. Clinical evaluation of the use of conventional glass-ionomer cements in the open-sandwich restoration has shown a high failure rate. The aim of this study was to evaluate the durability and cariostatic effect of a modified open-sandwich restoration utilizing a resin-modified glass-ionomer cement (RMGIC) in large cavities. The materials consisted of 274 mostly extensive Class II Vitremer/Z100 restorations performed by four dentists in 168 adults. Six experimental groups were investigated. In four groups a thick and in two groups a thin layer of cement was placed. Cavity conditioning before application of the RMGIC self-etching primer was done in 3 groups with polyacrylic acid and in one group with maleic acid; in two groups, only water rinsing was performed. The restorations were evaluated at baseline and after 6, 12, 24, and 36 months according to modified USPHS criteria (van Dijken, 1986). After 3 years, 239 restorations were evaluated. Twelve (5%) were estimated as non-acceptable. Two were replaced, and seven were repaired with resin composite. Tooth fractures were observed in 2.5%. Slight erosion of the RMGIC part was seen in 4%, and in one case operative treatment was indicated. Post-operative sensitivity was reported for 9 teeth. Forty-three percent of the patients were considered as caries-risk patients. Only one restoration showed secondary caries. The three-year results indicated that the modified open-sandwich restoration is an appropriate alternative to amalgam including extensive restorations.     

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.     

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-veneered amalgam restorations

A procedure is described for the construction of composite resin veneers for large amalgam restorations. The resulting restoration combines the physical qualities of amalgam with the esthetic benefits of composite resins. Among the 14 restorations that have been studied for 2 years, none failed mechanically and minor surface discolorations have been satisfactorily corrected by polishing.     

Posterior amalgam restorations--usage, regulation, and longevity

The use of dental amalgam has declined, but in most of the world, amalgam is the most widely used and widely taught direct restorative material for load-bearing posterior restorations. There are few national regulations on the use of amalgam; however, there are several nations where few amalgam restorations are placed. Long-term studies have shown that under optimum conditions, posterior restorations of amalgam and resin composite last longer than reported previously and that amalgam restorations outlast composite restorations. In general practice settings, posterior amalgam and composite restorations both have lower longevities.     

Marginal fracture of posterior composite resins

This study assesses the early cavomarginal breakdown of the newer posterior composite resin restorations compared with that of amalgam restorations. A total of 432 posterior composite restorations and 73 amalgam restorations were examined: 121 composite restorations (28%) and 44 amalgam restorations (60%) clinically showed a marginal crevice at some point on the cavosurface margin of the restoration at 6-month, 1-year, and 2-year recalls. The largest single reason for poor marginal adaptation was marginal fracture. Up to 2 years, the marginal integrity of the studied posterior composites was superior to that of an amalgam alloy. It was determined that smaller cavities, greater bulk of resin at the margin (especially at functional cusp areas), and well-finished margins without overfiling seem to reduce the occurrence of marginal fracture on composite resin restorations.     

Buonocore Memorial Lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition

This review provides a survey on the longevity of restorations in stress-bearing posterior cavities and assesses possible reasons for clinical failure. The dental literature, predominantly since 1990, was reviewed for longitudinal, controlled clinical studies and retrospective cross-sectional studies of posterior restorations. Only studies investigating the clinical performance of restorations in permanent teeth were included. Longevity and annual failure rates of amalgam, direct composite restorations, compomers, glass ionomers and derivative products, composite and ceramic inlays and cast gold restorations were determined for Class I and II cavities. Mean (SD) annual failure rates in posterior stress-bearing cavities are: 3.0% (1.9) for amalgam restorations, 2.2% (2.0) for direct composites, 3.6% (4.2) for direct composites with inserts, 1.1% (1.2) for compomer restorations, 7.2% (5.6) for regular glass ionomer restorations, 7.1% (2.8) for tunnel glass ionomers, 6.0% (4.6) for ART glass ionomers, 2.9% (2.6) for composite inlays, 1.9% (1.8) for ceramic restorations, 1.7% (1.6) for CAD/CAM ceramic restorations and 1.4% (1.4) for cast gold inlays and onlays. Publications from 1990 forward showed better results. Indirect restorations exhibited a significantly lower mean annual failure rate than direct techniques (p=0.0031). Longevity of dental restorations is dependent upon many different factors, including material, patient- and dentist-related. Principal reasons for failure were secondary caries, fracture, marginal deficiencies, wear and postoperative sensitivity. We need to learn to distinguish between reasons that cause early failures and those that are responsible for restoration loss after several years of service.     

Greening of the tooth-amalgam interface during extended 10% carbamide peroxide bleaching of tetracycline-stained teeth: a case report

At-home bleaching with 10% carbamide peroxide in a custom-fitted tray has been shown to have some minor effects on certain brands of amalgam, pertaining to mercury release, but generally, effects on amalgam are not considered clinically significant. However, in this case report, a greening of the tooth structure in certain areas immediately adjacent to amalgam restorations in the maxillary and mandibular first molars occurred during tooth whitening. Other amalgam restorations in mandibular and maxillary second molars in the same mouth did not demonstrate any green discoloration of the teeth. Upon removal of the affected amalgam restorations, recurrent decay was present in the areas of tooth greening but not in other areas adjacent to the restoration. The teeth were restored with posterior composite restorations. Whether the green discoloration was a result of some loss of material from a particular brand of amalgam, indicating leakage, or indicative of original or recurrent tooth decay is unclear in this single-patient situation. Other patients in the same study did not demonstrate this occurrence. Dentists should be ready to replace amalgam restorations should this green discoloration in adjacent tooth structure occur during bleaching, in case decay is present.
CLINICAL SIGNIFICANCE
The unusual discoloration cited suggests that amalgam restorations in potentially esthetic areas, including the lingual of anterior teeth, should be replaced prior to bleaching, to avoid the problem of difficult stain removal or translucency allowing restoration visibility following bleaching.     

A practice-based,randomized, controlled clinical trial of a new resin composite restorative: one-year results

This study evaluated the performance of a low-shrinking resin composite compared with an amalgam for restoration of Class I and II cavities of moderate size in posterior teeth in a general practice setting. Fifty-two pairs of test and control restorations were placed in 49 patients. Clinical evaluations and assessments of replica models were carried out at baseline, six months and one year. Patients recorded their level of satisfaction with the restorations by means of visual analog scales. Apart from one control restoration that failed due to a fractured cusp, all of the restorations reviewed at six months and one year were intact with no unacceptable scores for any of the evaluation criteria. It was concluded that the resin composite evaluated, when used in conjunction with the recommended adhesive system, may be an appropriate alternative to amalgam in the restoration of posterior teeth over one year in clinical service.     

Resin-based composites and compomers in primary molars

Resin-based composite resins and polyacid-modified resin-based composites (compomers) have become popular for the restoration of primary anterior and posterior teeth. In some European countries, resin-based composites or glass-ionomers are the materials of choice for primary teeth because of the controversy over dental amalgam and its alleged adverse health effects resulting from the release of mercury, although a clear correlation between amalgam restorations and health has not been determined. Another reason for the worldwide increased use of resin-based composites and glass-ionomers in pediatric dentistry could be attributed to the growing demand from parents to provide esthetic restorations to their children. More conservative preparations can be performed maintaining more tooth structure because of the adhesive properties of the composites and compomers. The most conservative treatment planning and meticulous care in the placement of the resin-based composites and compomers would produce long-term satisfactory results. These restorations should be placed in patients with low-to-moderate caries risk, and after placement the restorations should be monitored carefully to avoid complications mainly produced by recurrent caries and wear.     

Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial

BACKGROUND: Failure of dental restorations is a major concern in dental practice. Replacement of failed restorations constitutes the majority of operative work. Clinicians should be aware of the longevity of, and likely reasons for the failure of, direct posterior restorations. In a long-term, randomized clinical trial, the authors compared the longevity of amalgam and composite. SUBJECTS, METHODS AND MATERIALS: The authors randomly assigned one-half of the 472 subjects, whose age ranged from 8 through 12 years, to receive amalgam restorations in posterior teeth and the other one-half to receive resin-based composite restorations. Study dentists saw subjects annually to conduct follow-up oral examinations and take bitewing radiographs. Restorations needing replacement were failures. The dentists recorded differential reasons for restoration failure. RESULTS: Subjects received a total of 1,748 restorations at baseline, which the authors followed for up to seven years. Overall, 10.1 percent of the baseline restorations failed. The survival rate of the amalgam restorations was 94.4 percent; that of composite restorations was 85.5 percent. Annual failure rates ranged from 0.16 to 2.83 percent for amalgam restorations and from 0.94 to 9.43 percent for composite restorations. Secondary caries was the main reason for failure in both materials. Risk of secondary caries was 3.5 times greater in the composite group. CONCLUSION: Amalgam restorations performed better than did composite restorations. The difference in performance was accentuated in large restorations and in those with more than three surfaces involved. CLINICAL IMPLICATIONS: Use of amalgam appears to be preferable to use of composites in multisurface restorations of large posterior teeth if longevity is the primary criterion in material selection.     

The integrity of bonded amalgam restorations: a clinical evaluation after five years

BACKGROUND: Bonded amalgam restorations have been studied extensively in vitro, but few long term clinical studies exist. The authors examined the clinical performance of bonded amalgam restorations after five years of clinical service an compared it with that of nonbonded amalgam restorations. METHODS: The authors placed 75 bonded and 62 nonbonded amalgam restorations in patients needing restorations. Most of the restorations were placed in conventional preparations; six bonded restorations were placed in nonretentive cavities. They were evaluated after a five-year period of clinical service by two trained dentists using a mirror and explorer and following modified U.S. Public Health Service criteria. RESULTS: Statistical analysis (via Fisher exact test) showed no significant differences between the two techniques when conventional preparations were used. Restorations in nonretentive preparations were successful during this period. CONCLUSIONS: Bonded and nonbonded amalgam restorations yielded similar results in conventional preparations after five years of clinical service. Bonded amalgam restorations were clinically successful in a limited number of nonretentive preparations over a five-year period. CLINICAL IMPLICATIONS: Bonded amalgam restorations can be used successfully in conventional preparations and possibly in nonretentive preparations as well, and can be expected to last at least five years.     

Posterior composite resin inlays and onlays: a comparison of available systems

With the increasing proliferation of materials and techniques for placement of posterior composite resin restorations, the dentist must have the information to make informed judgements on which to use in various clinical situations. This paper examines the advantages and disadvantages of each of three systems: 1) Direct, 2) Direct/Indirect and 3) Indirect. The increased demand for posterior esthetic restorations has been one of the hallmarks of the eighties. According to a recent American Dental Association survey, the use of resin restorations in posterior teeth is markedly increasing and is the restoration of choice over amalgam for 70 percent of those dentists who responded to the survey. For the restorative dentist who chooses to do posterior esthetic restorations, the biggest challenge lies in acquiring the knowledge and judgement to know which of the three current classes of materials and techniques to apply to each clinical situation. Although the influx of new materials into the marketplace makes it difficult to evaluate and categorize these materials as accurately as would be desired, generally, posterior composite resins can be classified in three general categories based on method of placement. These categories are: a) Direct placement b) Direct/Indirect placement or Direct Composite Inlay (DCI) c) Indirect placement     

Dentists' molar restoration choices and longevity: a web-based survey

STATEMENT OF PROBLEM: The increasing trend toward esthetics has led to controversy as to the longevity of esthetic restorations and the wisdom of having traditional restorations replaced for esthetic reasons. With the assumption that the way dentists treat their own teeth may be a good indication of the accumulated wisdom of the profession, knowledge of dentists' own restorative choices may provide guidance in selecting the most appropriate restorations. PURPOSE: The purpose of this article was to determine restorative choices of dentists for personal molars and estimate restoration longevity. MATERIAL AND METHODS: Information about dentists' molars was obtained from a Web-based survey designed to receive dentists' demographic data and charting of 8 molar teeth with estimated longevity. Approximately 12,000 e-mails asking to access the website were sent to dentists' addresses randomly selected from a commercial database. Nonrespondents received 1 reminder. The responses were statistically analyzed with a chi-square analysis (alpha=.05). RESULTS: Seven hundred fifty-seven valid replies provided information for 6,034 teeth (22% unrestored, 75% restored, 2% missing). Restorations reported included amalgam (36%), gold inlay/onlay (13%), complete veneer crown (CVC) (10%), metal-ceramic crown (MCC) (8%), and composite (7%). Other esthetic options accounted for less than 3%. Restorations with more than 20 years longevity included amalgam restorations (58%), gold inlays/onlays (48%) and crowns (23%). Fifty-six percent of esthetic restorations and 5% of amalgams were placed in the last 5 years. The following restorations were placed in the last year (n=186): 38% esthetic, 29% crowns (18% MCC; 11% CVC), and 17% gold inlay/onlay or amalgam. Significant differences (P<.001) were identified for dentist's gender, year of graduation and practice location. CONCLUSIONS: Most dentists have not replaced traditional metallic restorations with esthetic alternatives. Dentists still choose nonesthetic options for significant numbers of their own restorations.     

Enamel-dentinal adhesives in amalgam restorations. Review of the literature

Amalgam is still the material most often used to restore posterior teeth, since it is easy to use, it has a low cost and a long clinical life. However, its use requires the solutions of several problems: lack of adhesion to tooth structure, marginal leakage, postoperative sensitivity and susceptibility to corrosion. In order to combine the advantages of dentinal adhesives with the excellent mechanical properties and good long clinical behaviour of amalgam, their use under amalgam restorations has been proposed. Adhesives improve marginal sealing and guarantee an additional retention to restorations, due to the formation of a layer linked with micromechanical bonds both to the tooth and the amalgam; they create a barrier that occludes dentinal tubules access, protecting the pulp. In this article the results of several in vitro studies performed to assess amalgam restorations properties are summarized. Present knowledge, based on an accurate literature review, allows to consider bonded amalgam restorations as a real progress in conservative dentistry: if long-term longitudinal studies, that are presently carried out, confirm the good short-term results, bonded restorations will represent the solution of choice for amalgam application.     

Despite all--do we have an appropriate substitute for amalgam?

The ultimate success or failure of a restored tooth is largely dependent on clinical management. Clinicians may choose from a number of restorative materials, different clinical techniques and cavity preparation procedures. Composite resin has been used for nearly 50 years as a restorative material in dentistry. The use of this material has recently increased as a result of patients' demands for esthetic restorations. Failure of dental restorations is a major concern in dental practice. Replacement of failed restorations constitutes the majority of operative work. Clinicians should be aware of the longevity of, and likely reasons for the failure of, direct posterior restorations. Higher failure rates were observed in resin-based composite restorations as compares amalgam restorations. Secondary caries was the main reason for failure. Posterior interproximal resin-based composite restorations should be considered with caution, and their limited long-term performance should be kept in mind. Patients should be informed about the potential longevity of restorative treatment for posterior teeth as they make decisions about treatment for their oral restorative needs.     

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.     

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.     

Amalgam--Resurrection and redemption. Part 1: the clinical and legal mythology of anti-amalgam.

Dental amalgam has come under attack for its allegedly poor physical properties and clinical performance in addition to its poor appearance. It has been claimed that the American Dental Association has a hidden agenda to protect amalgam and that other countries have banned its use. A literature search revealed that the vast majority of amalgam restorations do not cause fractured cusps or have recurrent caries. Most amalgam restorations have been shown to last longer than resin composite restorations. In addition, the materials and techniques involved in amalgam restorations have vastly improved in recent years. Like resin composite restorations, amalgam restorations can often be repaired. The American Dental Association has no vested interest in protecting amalgam. The use of amalgam has not been banned in any country in the European Union. According to the latest scientific information available, dental amalgam is a remarkably durable and long-lasting restorative material. Although its appearance is unesthetic, its clinical performance and effectiveness are unsurpassed by those of resin composite.