Authors' objectives

To assess the evidence on single-tooth restorations (STRs) supported by implants, and to aggregate overall survival results.

Searching

MEDLINE was searched from 1990 to April 1998 using the terms 'dental in SB', 'implant*' and 'single'. Conference abstracts and non-English language papers were excluded.

Study selection

Assessment of study quality

Validity was assessed formally using a modification of the quality scoring system described by Antczak et al. and Kreulen et al. (see Other Publications of Related Interest nos.1-3). The studies were evaluated as to whether they represented good scientific practice (GSP), on the basis of criteria covering the areas of study methodology, dental methodology, evaluation methodology, and statistical methodology. Each criteria was marked with 3 points for full credit, 2 points for partial credit and 1 point for no credit. The total criteria score for each study was transferred to a scale from 0 to 1, and the result referred to as the 'GSP-score'.

Two authors independently performed the validity assessment. The authors were blinded to the papers' identifying details, working only with copies of the 'Materials and Methods' and 'Results' sections of the included papers.

Data extraction

Two authors independently extracted the data. The authors worked only with copies of the 'Materials and Methods' and 'Results' sections of the included papers.

Information on common study outcomes was extracted from the included studies, and the numbers and proportions of failed STRs and implants (censoring, i.e. resulting from implant failure, included) were traced.

Methods of synthesis

Results of the review

Ten studies were included in the review. One of these was subsequently excluded at the third stage of the selection process because of a lack of statistical homogeneity for the outcomes after 2 years of follow-up. The remaining nine studies presented a total of 459 single-tooth implants.

At the first selection of papers (332 papers), observer agreement (kappa) was 0.79 (plus or minus, +/- 0.04).

At the second selection of papers (49 papers), full agreement was only observed for the items 'paper in English', 'follow-up period' and 'implant system'.

At the third selection of papers (26 papers), kappa ranged from 0.09 for the item 'numbers' (percentage agreement 50%) to 1 for the items 'evaluation criteria' and 'statistical procedures' (percentage agreement 100%).

For overall validity assessment, the data showed an overall mean GSP score of 0.37.

The 4-year implant survival for 459 single-tooth implants was 97% (+/- 1).

The 4-year combined STR survival, based on four studies (240 STRs) that presented appropriate data for this item, was 83% (+/- 3).

The homogeneity test revealed no differences between the outcomes of the studies after 2 years' follow-up, except for one study, which showed significantly more STR complications. The results of this study were excluded from the review.

Authors' conclusions

Single-tooth implants showed an acceptable short-term survival of 4 years, but crown complications were common. It was stated that only a small portion of the published data on restorative treatments could be used for inference.

CRD commentary

The authors stated their research question and the inclusion and exclusion criteria. The literature search was limited although there was an attempt to search for unpublished data. While English language publications were later excluded, the process revealed that these papers would have been excluded for not meeting other selection criteria. The authors report who, and how many of the reviewers, performed the study selection, quality assessment and data extraction processes. There was an extensive three-stage assessment of the included studies, which was based on a formal validated scoring system. The review's authors also made extensive additions to the validation process.

The statistical pooling presented survival curves and survival estimates for the stated outcomes. There was a detailed investigation regarding the homogeneity of the included studies, with a discussion at each stage of the review on the effects of excluding different sets of papers.

The authors' conclusions appear to follow from the results. They present an extensive procedure for the validity assessment of studies included in a systematic review in the field of dentistry.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors state that further standardisation of clinical study methodology and reporting methodology will contribute to the effective summation of results.

Funding

University of Nijmegen; Netherlands Institute for Dental Sciences.

Bibliographic details

Creugers N H, Kreulen C M, Snoek P A, de Kanter R J. A systematic review of single-tooth restorations supported by implants. Journal of Dentistry 2000; 28(4): 209-217. [PubMed: 10722893]

Other publications of related interest

1. Antczak AA, Tang J, Chalmers TC. Quality assessment of randomized control trials in dental research (II). Results: periodontal research. J Periodontal Res 1986;21:315-21. 2. Hayes C, Antczak-Bouckoms A, Burdick E. Quality assessment and meta-analysis of systematic tetracycline use in chronic adult periodontitis. J Clin Periodontol 1992;19:164-8. 3. Kreulen CM, Creugers NH, Meijering AC. Meta-analysis on anterior veneer clinical studies. J Dent 1998;26:345-53. 4. Cohen J. A coefficient of agreement for nominal scales. Educ Psychol Meas 1960;20:37-46.

Indexing Status

Subject indexing assigned by NLM

MeSH

Clinical Trials as Topic /standards; Dental Implantation, Endosseous; Dental Implants, Single-Tooth; Dental Research /standards; Dental Restoration Failure; Evidence-Based Medicine; Humans; Journalism, Dental /standards; MEDLINE; Outcome Assessment (Health Care) /methods; Survival Analysis

AccessionNumber

12000000832

Database entry date

30/11/2002

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.