A systematic review of single crowns on endodontically treated teeth

CRD summary

The authors concluded that root canal-treated teeth covered with crowns demonstrated an acceptable long-term survival. Direct restoration (such as resins, amalgams and cements) had only a satisfactory survival period. Due to the methodological limitations of this review, the authors conclusions are unlikely to be reliable.

Authors' objectives

To assess the performance of single crowns and restorations on endodontically treated teeth.

Searching

MEDLINE was searched from 1960 to 2006; search terms were reported. The authors handsearched library indexes. Only English-language publications were included in the review. Studies published as abstracts were excluded from the review.

Study selection

No inclusion criteria regarding participants were reported.

Studies that examined single crowns and/or direct restorations (such as resin composites, amalgam, cements) on root canal-treated teeth were selected for inclusion. Eligible studies had to report the success of crowns and restorations (or rather, the absence of failure). Failure of root canal-treated teeth restorations was defined as fracture of the tooth, fracture of the restoration, post fracture, post de-cementation, dislodgement of the restoration, marginal leakage of the restoration and tooth loss.

Clinical studies with sufficient data on individual teeth to calculate life table curves were eligible for inclusion in the review. Descriptive studies, reviews, and case reports were excluded. Studies with a follow-up period less than two years were also excluded from the review.

Two reviewers performed the selection.

Assessment of study quality

The quality of the studies was assessed using a published checklist relevant to dental research. Twelve criteria were evaluated and weighted using the following broad categories: study aims; study methodology (type of study, allocation concealment, heterogeneity, description of participant characteristics, follow-up data); dental methodology; evaluation methodology; and statistical methodology. The results were mathematically transformed resulting in a mean score for each criteria (details of this process were provided in the paper). Two authors assessed quality independently.

Data extraction

In addition to the outcome data of interest, information on the type of restoration, number of patients, number of teeth evaluated, foundation type and tooth type was data extracted. In one study, outcome data were obtained from figures.

Methods of synthesis

The data were pooled to estimate life table survival curves. It appeared that a post-hoc decision was made to evaluate crowns and restorations separately. Homogeneity was assessed by comparing the percentage of two-year survival (and confidence interval) of each study with the overall survival at the two-year follow-up. It was noted that failures independent of clinical aging and fatigue processes were considered to be early failures and were excluded from the survival analyses.

Results of the review

Ten studies were included in the review. The study designs and sample sizes of the included studies were not reported. It appeared that most of the included studies were retrospective.

The quality scores for each study were not reported; mean scores for all studies were reported for each criteria assessed.

Five studies were analysed to construct survival curves for root canal-treated teeth covered with crowns: the combined survival was 81% plus or minus 12 after 10 years.

Eight studies were analysed to construct survival curves for root canal-treated teeth without crowns (that is, with restorations): the combined survival was 63% plus or minus 15 after 10 years.

Authors' conclusions

Root canal-treated teeth covered with crowns demonstrated an acceptable long-term survival; direct restorations had only a satisfactory survival period.

CRD commentary

While it was apparent that the authors employed rigorous inclusion assessment procedures, the inclusion criteria were not clearly presented for participants or study design. The search included one database and handsearching. Non-published studies and non-English studies were not sought, which may have introduced publication and language biases. The validity of the studies was assessed. The results for individual studies were not reported, but were summarised for each quality criteria. It appeared that the quality of the included studies was generally low. It appeared that two authors were involved in the quality assessment and study selection processes, thus limiting some reviewer bias. The authors did not report clearly how many reviewers were involved in data extraction process. Details of the individual studies were not presented in this review. The data were summarised using life table survival curves, but it appeard that the results were separated into two groups in a post-hoc manner. Overall, due to the methodological limitations of this review, the authors conclusions are unlikely to be reliable.

Implications of the review for practice and research

The authors did not state any implications for practice or research.

Funding

Not stated.

Bibliographic details

Stavropoulou A F, Koidis P T. A systematic review of single crowns on endodontically treated teeth. Journal of Dentistry 2007; 35(10): 761-767. [PubMed: 17822823]

Original Paper URL

http://www.jodjournal.com/article/S0300-5712(07)00131-5/abstract

Indexing Status

Subject indexing assigned by NLM

MeSH

Acrylic Resins; Composite Resins; Crowns /statistics & numerical data; Dental Amalgam /chemistry; Dental Restoration Failure; Dental Restoration, Permanent /methods; Humans; Polyurethanes; Survival Analysis; Tooth, Nonvital /therapy

AccessionNumber

12008103207

Database entry date

19/08/2009

Record Status

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.