This review assessed the long-term success, survival and complications of fixed partial dentures. The authors concluded that the most common biological complications were caries and loss of abutment vitality, while the most common technical complication was loss of retainer retention. Aspects of the review were well conducted, but differences among the studies cast doubt on the reliability of some summary estimates.

To assess the long-term success, survival and complications of fixed partial dentures (FPDs).

MEDLINE was searched for inception to April 2004 for studies published in English in the dental literature; the search terms were reported. Bibliographies of previous reviews and all publications were screened.

Study designs of evaluations included in the review

Prospective and retrospective cohort studies with a mean follow-up period of at least 5 years were eligible for inclusion. The included studies followed up patients for 1 to 25 years.

Specific interventions included in the review

Inclusion criteria for the interventions were not specified, but it was clear that studies of FPDs were included. Studies using FPDs and single crowns had used FPDs in at least two-thirds of cases. Studies of cantilever FPDs were examined in another review and were excluded (see Other Publications of Related Interest no.1). The included studies used a variety of different types of FPDs, with most of the studies reporting that the FPD design used gold-acrylic; others studies used metal-ceramic designs. The procedures were carried out by dental students and specialists, and were set in a university and specialist and private clinics.

Participants included in the review

Inclusion criteria for the participants were not specified. The patients in the included studies were aged from 13 to 90 years.

Outcomes assessed in the review

The studies had to examine all patients clinically at follow-up. Studies that assessed outcomes using patients' records, questionnaires or interviews were excluded. The review assessed survival, success, and biological and technical complications. Survival was defined as FPD still in situ regardless of condition. Success was defined as FPD unchanged and no interventions required during follow-up. Biological complications included caries, loss of pulp vitality and the progression of periodontal disease. Technical complications included loss of retention, fracture of abutment teeth and material fractures.

How were decisions on the relevance of primary studies made?

Two reviewers independently selected studies and resolved any disagreements through discussion. Inter-reviewer agreement was moderate (kappa 0.43).

The authors did not state that they assessed validity, but they did extract data on drop-outs.

Three reviewers independently extracted the data using a data extraction form and resolved any disagreements through discussion. Where possible, additional data were obtained from the authors of the primary studies. For each study, the numbers of events were extracted and the total exposure time calculated using various methods (the methods were reported). The reviewers then estimated the failure rates per 1,000 FPDs, and survival and complication rates (with 95% confidence intervals, CIs) after 10 years.

How were the studies combined?

Studies using similar designs were pooled using negative binomial regression with robust standard errors (equivalent to a random-effects Poisson regression model). Ten-year complication rates and 10-year survival rates (with 95% CI assuming a constant event rate) were calculated.

How were differences between studies investigated?

Outliers were identified from meta-analysis graphs. The meta-analyses were repeated after the exclusion of outliers.

Nineteen cohort studies (1,764 patients) were included: 2 prospective studies and 17 retrospective studies.

Drop-outs: where reported, the drop-out rates ranged from 3 to 75%.

FPD survival (13 studies, 2,881 FPDs): the estimated summary 10-year survival rate was 89.1% (95% CI: 81, 93.8; based on 9 studies). After excluding one outlier study with a higher rate of FPD loss, the summary survival rate was 92%.

Success (4 studies): the estimated summary 10-year success rate was 71.1% (95% CI: 47.7, 85.2). After excluding one outlier study with a higher rate of FPD complications, the summary survival rate was 81.1%.

Biological complications.

Dental caries at abutments (6 studies): the estimated 10-year cumulative rate was 9.5% (95% CI: 4.6, 18.9).

Dental caries on FPD level leading to loss of FPD (5 studies in meta-analysis): the estimated 10-year cumulative rate was 2.6% (95% CI: 1.6, 4.2).

Loss of abutment vitality (4 studies in meta-analysis): the estimated 10-year cumulative rate was 10% (95% CI: 5.7, 17.3).

Recurrent periodontitis (8 studies in meta-analysis): the estimated 10-year cumulative rate of FPDs lost to recurrent periodontitis was 0.5% (95% CI: 0.1, 2.2).

Technical complications.

Loss of retention (8 studies in meta-analysis): the estimated 10-year cumulative rate was 6.4% (95% CI: 3.9, 10.4). Two studies reported high rates.

Fracture of abutment teeth leading to FPD loss (7 studies in meta-analysis): the estimated 10-year cumulative rate was 2.1% (95% CI: 1.4, 3.2).

Material complications (10 studies in meta-analysis): the estimated 10-year cumulative rate of material complications was 3.2% (95% CI: 1.5, 6.5).

The most common biological complications were caries and loss of abutment vitality, while the most common technical complication was loss of retention of the FPD. Loss of FPD within 10 years on account of biological complications occurred in 2.6% because of caries and in 0.5% because of recurrence of periodontitis. The risk of FPD loss was greater with technical complications.

The review addressed a clear question in terms of the intervention, outcomes and study design, although the criteria were only explicit for study design. The search was limited to English language publications in one electronic database, therefore some relevant studies might have been missed. No attempts were made to locate unpublished studies, thus raising the possibility of publication bias. Methods were used to minimise errors and bias in the study selection and data extraction processes. Validity was not formally assessed although the drop-out rates were reported.

The studies were combined using a meta-analysis and some meta-analysis graphs were presented. The event rates for some outcomes varied across the studies, and summarising the data by meta-analysis was not appropriate for these situations. Outliers were identified and analyses were repeated after excluding them. However, the limited search and heterogeneity among studies cast doubt on the reliability of some summary estimates.

Practice: The authors stated that patients with extensive FPDs should be closely monitored for the loss of vitality in abutments.

Research: The authors did not state any implications for further research.

1. Pjetursson BE, Tan K, Lang NP, Bragger U, Egger M, Zwahlen M. A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years. IV. Cantilever or extension FPDs. Clin Oral Implants Res 2004;15:667-76.

2. Lang NP, Pjetursson BE, Tan K, Bragger U, Egger M, Zwahlen M. A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years. II. Combined tooth-implant-supported FPDs. Clin Oral Implants Res 2004;15:643-53.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.