Replacement of amalgams with crowns: a cost-effectiveness analysis

Treatment recommendations for single-unit crowns: Findings from The National Dental Practice-Based Research Network

BACKGROUND

The objectives of this study were to quantify practitioner variation in likelihood to recommend a crown and test whether certain dentist, practice, and clinical factors are associated significantly with this likelihood.

METHODS

Dentists in The National Dental Practice-Based Research Network completed a questionnaire about indications for single-unit crowns. In 4 clinical scenarios, practitioners ranked their likelihood of recommending a single-unit crown. The authors used these responses to calculate a dentist-specific crown factor (range, 0-12). A higher score implied a higher likelihood of recommending a crown. The authors tested certain characteristics for statistically significant associations with the crown factor.

RESULTS

A total of 1,777 of 2,132 eligible dentists (83%) responded. Practitioners were most likely to recommend crowns for teeth that were fractured, cracked, or endodontically treated or had a broken restoration. Practitioners overwhelmingly recommended crowns for posterior teeth treated endodontically (94%). Practice owners, practitioners in the Southwest, and practitioners with a balanced workload were more likely to recommend crowns, as were practitioners who used optical scanners for digital impressions.

CONCLUSIONS

There is substantial variation in the likelihood of recommending a crown. Although consensus exists in some areas (posterior endodontic treatment), variation dominates in others (size of an existing restoration). Recommendations varied according to type of practice, network region, practice busyness, patient insurance status, and use of optical scanners.

PRACTICAL IMPLICATIONS

Recommendations for crowns may be influenced by factors unrelated to tooth and patient variables. A concern for tooth fracture-whether from endodontic treatment, fractured teeth, or large restorations-prompted many clinicians to recommend crowns.

Clinical Decision Making on Extensive Molar Restorations

Extensive loss of posterior tooth substance, which traditionally was restored with amalgam or indirect restorations, is more commonly being restored with resin-based composite restorations. Using a questionnaire, we aimed to survey dentists' clinical decision making when restoring extensive defects in posterior molar teeth. The questionnaire, which included questions on background information from the dentists, clinical cases with treatment options, and general questions about restoring extensive posterior defects, was sent to 476 dentists. The response rate was 59%. Multiple logistic regressions were used to investigate the different associations. Most of the respondents preferred a direct composite restoration when one cusp was missing, while indirect restorations were most preferred when replacing three or four cusps. Younger dentists and dentists working in the private sector had a greater tendency to choose an indirect technique compared with older colleagues. Generally, the most important influencing factor in clinical decision making was the amount of remaining tooth substance. Factors that appeared to be less important were dental advertisements, use of fluoride, and dietary habits. Female dentists perceived factors such as oral hygiene, patient requests, and economy to be more important than did their male colleagues.

The Cost-Effectiveness of Large Amalgam and Crown Restorations Over a 10-Year Period

OBJECTIVE

To assist clinical decision making for an individual patient or on a community level, this study was done to determine the differences in costs and effectiveness of large amalgams and crowns over 5 and 10 years when catastrophic subsequent treatment (root canal therapy or extraction) was the outcome.

METHODS

Administrative data for patients seen at the University of Iowa, College of Dentistry for 1735 large amalgam and crown restorations in 1987 or 1988 were used. Annual costs and effectiveness values were calculated. Costs of initial treatment (large amalgam or crown), and future treatments were determined, averaged and discounted. The effectiveness measure was defined as the number of years a tooth remained in a state free of catastrophic subsequent treatment. Years free of catastrophic treatment were averaged, and discounted. The years free of catastrophic treatment accounted for individuals who dropped out or withdrew from the study.

RESULTS

Teeth with crowns had higher effectiveness values at a much higher cost than teeth restored with large amalgams. The cost of an addition year free of catastrophic treatment for crowns was 1088.41 dollars at 5 years and 500.10 dollars at 10 years. Teeth in women had more favorable cost-effectiveness ratios than those in men, and teeth in the maxillary arch had more favorable cost-effectiveness ratios than teeth in the mandibular arch.

CONCLUSIONS

Neither the large amalgam or crown restoration had both the lowest cost and the highest effectiveness. The higher incremental cost-effectiveness ratio for crowns should be considered when making treatment decisions between large amalgam and crown restorations.

Long-term cost-effectiveness of single indirect restorations in selected dental practices

OBJECTIVE

To determine the relative cost-effectiveness of alternative methods for restoring large tooth substance loss in adults.

METHODS

Long-term survival estimates and discounted costs for 245 large indirect restorations were used to calculate their incremental cost-effectiveness over 15 years when compared with direct placement Class II cusp-overlay amalgams and Class IV multisurface resin composites, placed in 100 patients from three private dental practices.

RESULTS

The direct placement restorations were more cost-effective than the indirect restorations at all time intervals over the 15-year study period. The full gold crown and the ceramometal crown were the most cost-effective indirect posterior and anterior restorations respectively. The cast gold onlay and the porcelain jacket crown were the least cost-effective indirect posterior and anterior restorations respectively.

CONCLUSIONS

When clinically practicable, large direct placement restorations should be placed initially in preference to indirect restorations.

New paradigms in prosthodontic treatment planning: a literature review

New treatment modalities have expanded the choices available to prosthodontists and their patients. At the same time, an explosion of data has called into question the validity and efficacy of certain forms of traditional prosthodontic treatment. Together, these factors have greatly complicated the treatment-planning process. The purpose of this article is to provide a framework for the prosthodontic treatment-planning process that incorporates the latest evidence-based information available. A review of the literature was undertaken through a Medline search. Articles published in English from 1975 through 2001 were evaluated; selected articles were chosen for review on the basis of a subjective judgment of their relevancy and significance to the clinician.

Decision analysis in dentistry--the last 30 years

OBJECTIVES

To review publications in dentistry of decision analyses during the last 30 years.

METHODS

A systematic review of the English literature from 1969 to 1998 was performed using specified indexing terms. The number of retrieved articles in dentistry was compared with the number of articles in medicine. The quality of articles in dentistry presenting a decision tree with utilities and a sensitivity analysis was judged using a published peer review process. We report weaknesses of the analyses together with selected applications.

RESULTS

Sixty-seven articles were published on decision analysis in dentistry. Whilst the number of articles published in medicine has accelerated there has been a decline in the last four years in dental publications. Only 22 of the articles in dentistry presented a decision analysis with utilities and a sensitivity analysis.

CONCLUSIONS

Current weaknesses of the decision analyses reported were: opaque basic assumptions in the description of the analysis, lack of data on patient preferences and of reliable data on the chances of the long-term effects and side effects of intervention together with an absence of sensitivity analyses. The decision analysis approach complements that of "evidence-based health care" by enabling the best empirical evidence to be used in clinical practice. Formal methods such as decision analysis will promote the rational use of existing knowledge. For it to do this the quality of research data will have to improve in dentistry. Furthermore decision analysis is important in education to demonstrate explicitly how decisions might be arrived at and improved.

Qualitative and quantitative determination of dental amalgam restoration volume

STATEMENT OF PROBLEM

Volume of tooth structure replaced by an existing restoration, as assessed by visual and radiographic examination, is one diagnostic measure used by dental practitioners and dental insurance agencies to determine the relative need to restore a tooth with a full-coverage cast restoration. However, use of these methods has not been validated.

PURPOSE

This study compared the volume of a range of dental amalgam restorations placed in typodont teeth, as estimated by dentists, dental students and laypersons, with the actual volume of each restoration.

METHODS AND MATERIAL

Sixty subjects (20 dental school faculty, 20 dental students, and 20 clerical staff [laypersons]) participated. After reviewing photographic images of typodont teeth with mesial-occlusal-distal dental amalgam restorations, subjects estimated the volume of each restoration using various restorations on different teeth as a percentage of its tooth's coronal volume. The actual volume of each dental amalgam restoration and that of the coronal portion of the prepared teeth was calculated with a volumetric displacement technique. The single sample 2-sided t test with a.05 level of significance was used to evaluate the null hypothesis (H0 ): The survey participant's estimates of each restoration's percentage volume are the same as the measured volume values versus the alternative hypothesis (H1 ): estimates differed from the measured volume values. One-way analysis of variance was used to determine the significance of any difference between the estimates of the 3 survey test groups.

RESULTS

Average volumes reported by all 3 groups were significantly different than the measured volume values (P <.05). Experience and dental training did not significantly affect a participant's ability to evaluate restoration volumes with greater accuracy. Results reported by dentists, dental students, and laypersons were not significantly different (P >.05).

CONCLUSIONS

The volume of a restoration is inaccurately assessed by visual and radiographic examination.

Methods of evaluating dental care costs in the Swedish public dental health care sector

Twenty-six Swedish dental health care clinics participating in the intervention study "Evaluation of caries preventive measures" have been analysed with focus on costs, with the aim of demonstrating techniques suitable for evaluating direct dental care costs and also finding out whether charges are acceptable as a proxy for real costs. Three different approaches to calculating unit costs are discussed: average treatment time cost and two methods of different allocation of overhead cost. Average treatment time cost shows treatment time cost regardless of who (dentist, dental hygienist or nurse) provides the dental care. The other two methods reflect both the differences of treatment costs depending on practitioners' skill level and competence (salary) and the methods of handling overhead cost allocation. Our conclusions are that the proposed methods seem useful for evaluating costs in cost-effectiveness and cost-benefit analysis. The alternative to average treatment time cost or unit time cost depends on what data is available and the perspective of the analysis. This study also concludes that charges are not sufficient as an alternative to a more detailed cost evaluation, at least not in Swedish public dental health care, since charges do not cover costs.

Long-term survival of extensive amalgam restorations

In cost-effectiveness analysis and contemporary treatment planning strategies, the postponement of placement of cast crowns plays an important role. Extensive amalgam restorations that involve the rebuilding of cusps and the provision of auxiliary retention are thought to make this postponement possible. This study reports the long-term survival (100 months) of extensive amalgam restorations in a randomized, controlled clinical trial. The operational hypothesis was that the type of retention and the operator have a long-term influence on the survival and clinical functioning of extensive amalgam restorations. Three hundred extensive amalgam restorations were placed by three operators in molar teeth in which one or more cusps were reconstructed. Five different auxiliary retention methods were used for retention of these restorations. Since the purpose of extensive amalgam restorations is considered to be two-fold (to restore a broken-down molar to function acceptably as an independent restoration and to create a substructure for subsequent crown construction), survival was assessed at different levels. The survival rate of extensive amalgam restorations as an independent restoration was 88+/-2%. The functional survival rate (as an independent restoration or as a substructure) was 92+/-2%. The influence of experimental variables ('retention method' and 'operator') and background variables ('tooth type', 'extension of extensive amalgam restorations', and 'age of patient') on the survival was analyzed by Log Rank and Breslow tests. The analyses revealed that there were no statistically significant influences on the survival rates except for the variable 'age of patient' (p < or = 0.05). Extensive amalgam restorations were more prone to failure in the group of older patients than in the group of younger ones. It is concluded that the clinical survival of extensive amalgam restorations is independent from several clinical variables in the study.

A 4-year clinical evaluation of extensive amalgam restorations--description of the failures

The 4-year evaluation of a randomized controlled clinical trial to the functioning of Extensive Amalgam Restorations (EAR) is reported. In this trial 300 EAR were made by three operators on molar teeth. Five different auxiliary retention methods were used to retain these restorations. In the evaluation a differentiation in 'absolute' and 'relative' failures was made. After 4 years seven absolute failures (EAR dislodged or removed) were encountered (2%). When relative failures (endodontic treatment or restoration at margin) are also taken into account the number of failures increased to 31 (10%). Due to the low number of failures, no significant influences from experimental variables (c.q. retention method or operator) could be detected. It may be concluded that the results of this interim analysis of the clinical functioning of EAR are promising. It is thought that careful evaluation of cusp strength and reducing weak cusps diminishes clinical failure and as a result, it is not necessary to protect an EAR with a cast restoration in the first 4 years of its clinical life.

Cost-conservative dentistry: appropriate dentistry at lower cost

Dental practitioners in both private and public dentistry are faced with patients who for reasons of public or private finance are not able to be treated with the most sophisticated available dentistry. A concept of appropriate dentistry is provided whereby, with reference to available literature, it is shown that cost-conservative treatment can be provided that is likely to be satisfactory to both the client and the practitioner.

Cost-effectiveness decision analysis of obtaining periapical radiographs of traumatized maxillary incisors

A long-term decision analysis approach has been applied to the problem of whether or not periapical radiographs should be taken routinely of patients presenting with simple fractures of otherwise asymptomatic maxillary incisors. Information from the literature concerning the accuracy of cold, hot and electrical tests for pulp vitality, combined with data on the accuracy of radiographic diagnosis of periapical pathology, and therefore vitality, has been used in the analysis of the diagnostic problem structured in the form of a decision tree. By adding information concerning the direct costs of examining and treating patients over a 10-year period to the analysis and varying the likely prevalence of periapical lesions in a three-way sensitivity analysis, the following results were arrived at: (1) if the disease prevalence in teenage patients is < 5%, it is economically justifiable to make a visual inspection only and then to proceed with simple restorative treatment; (2) if there is evidence from the clinical examination or patient history that the prevalence of pulp necrosis is between 5% and 50% then, in our case, radiographs were the most appropriate single diagnostic test.

Expert systems in dentistry. Past performance--future prospects

Expert systems are knowledge-based computer programs designed to provide assistance in diagnosis and treatment planning. They assist the practitioner in decision making. A search of the literature on expert system design for medical and dental applications was carried out. It showed an increase in the number of articles on this subject. Between 1984 and 1991, 608 articles have been published in medical journals and two in dental journals. Because it is likely that this development will influence dental practice in the future a critical review of medical literature on the topic has also been carried out. A number of general principles are described to give the dental practitioner some insight into how expert systems work. A set of criteria have been formulated from the medical literature which expert systems should meet. These requirements are also applicable to dentistry and may be used to judge dental expert systems. In the last part of the paper the features of several dental expert systems developed in the past decade are described in the light of these criteria. It is concluded that in the future more attention should be paid to the development and evaluation of expert systems in the clinical setting. Only well-designed and properly evaluated expert systems can be expected to earn a place in everyday practice.

Decision making in dentistry. Part II: Clinical applications of decision methods

The study of clinical decision making provides a common model on which to base dental practice and thus promotes standardization of care and treatment. Decision analysis can assist in identifying missing data in clinical problems and thus generate clinically relevant research agendas. Part II reviews the current literature focusing on three areas of decision making in dentistry: diagnosis, treatment planning, and disease prediction. The growing body of literature indicates that wide variation exists among the treatment plans made by dentists. Considerable bias arises from many sources of uncertainty in decision making, including the limitations of human memory and judgment. Literature pertaining to computer application of decision analysis in dentistry and to policy making are reviewed.