The aim of this overview was to evaluate and compare the quality of systematic reviews, with or without meta-analysis, that have evaluated studies on techniques or biomaterials used for the preservation of alveolar sockets post tooth extraction in humans. An electronic search was conducted without date restrictions using the Medline/PubMed, Cochrane Library, and Web of Science databases up to April 2015. Eligibility criteria included systematic reviews, with or without meta-analysis, focused on the preservation of post-extraction alveolar sockets in humans. Two independent authors assessed the quality of the included reviews using AMSTAR and the checklist proposed by Glenny et al. in 2003. After the selection process, 12 systematic reviews were included. None of these reviews obtained the maximum score using the quality assessment tools implemented, and the results of the analyses were highly variable. A significant statistical correlation was observed between the scores of the two checklists. A wide structural and methodological variability was observed between the systematic reviews published on the preservation of alveolar sockets post tooth extraction. None of the reviews evaluated obtained the maximum score using the two quality assessment tools implemented.
Decision-making in medicine should be supported by scientific evidence. Specifically in dentistry, decisions should be conscientious, explicit, and judicious, taking into consideration the best available evidence for the care of each patient. In this context, systematic reviews and randomized clinical trials provide the most reliable sources of scientific evidence for health interventions, and systematic reviews of randomized clinical trials (RCTs) are top of the scientific hierarchy.
Despite the increase in publications, there is evidence that the quality of scientific data in healthcare is questionable, including systematic reviews in dentistry. In recent years, several guidelines have been developed with the aim of increasing the transparency and quality of research. Some of these guidelines can be accessed from the EQUATOR Network website ( www.equator-network.org ). In 2009, a checklist designated the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was proposed, with the aim of presenting conceptual and practical elements for the preparation of systematic reviews, with or without meta-analysis.
The introduction of tools for the assessment of systematic reviews, including the assessment of multiple systematic reviews (AMSTAR), allows researchers to critically evaluate the methodological quality of systematic reviews in the area of biomedical sciences. Currently, more than 50 systematic reviews are published each month, featuring different methodologies. This may lead to different interpretations by professionals and consequently influence clinical decision-making. In periodontics, for example, numerous systematic reviews have been published on techniques and biomaterials used for the preservation of alveolar sockets post tooth extraction.
The preservation of the alveolar socket is a procedure performed at the time of tooth extraction to minimize the absorption of external tissue and maximize the formation of bone tissue inside the socket. Tissue loss after tooth extraction is physiological and progressive, and is more pronounced during the first 3–6 months after extraction, followed by less intense resorption throughout the patient’s life. Therefore, preservation of the margin volume after tooth extraction is essential to achieving a successful outcome, and to improve the predictability of the aesthetic success of treatments using dental implants.
The purpose of this overview was to assess and compare the quality of systematic reviews, with or without meta-analysis, that have evaluated studies on the techniques or biomaterials used for the preservation of post-extraction sockets in humans.
Materials and methods
Decision-making in medicine should preferably be supported by scientific evidence, and systematic reviews top the scientific hierarchy in this respect. The critical analysis of published systematic reviews and meta-analyses may help to indicate their strengths and weaknesses and to identify areas that require further improvement.
The aim of this study was to evaluate and compare the quality of systematic reviews, with or without meta-analysis, that have evaluated studies on the techniques or biomaterials used for the preservation of post-extraction sockets in humans.
Only systematic reviews (with or without meta-analysis), without date restrictions, published in English and focused on the preservation of post-extraction sockets in humans were included in this study. Descriptive and narrative reviews, as well as in vitro and animal studies, were excluded.
Search strategy and data screening
An electronic search without date restrictions was conducted using the Medline/PubMed, Cochrane Library, and Web of Science databases up to April 2015. Moreover, a manual search was conducted in the following journals: Journal of Periodontology , Journal of Clinical Periodontology , Journal of Periodontal Research , International Journal of Periodontics and Restorative Dentistry , Clinical Oral Implants Research , Clinical Implant Dentistry and Related Research , International Journal of Oral and Maxillofacial Implants , International Journal of Oral and Maxillofacial Surgery , Implant Dentistry , Journal of Dentistry , Journal of Prosthodontics , and the Journal of Dental Research . Additional studies were researched in the grey literature and in references from the studies included (cross-referencing).
The search and screening processes for article selection were performed by the two authors/reviewers, who first analyzed the titles and abstracts. Complete articles were then selected for critical reading and were analyzed according to the eligibility criteria (inclusion/exclusion) for future data extraction. Any differences between the reviewers were resolved through careful discussion. Concordance between the author/reviewer searches was evaluated by statistical analysis using Cohen’s kappa ( κ ) test. The study authors were contacted by e-mail for clarification where necessary. The following key words were searched for in all databases: “alveolar socket preservation”, “socket preservation”, “alveolar ridge preservation”, “ridge preservation”, “tooth socket”[MeSH], “alveolar ridge”[MeSH], “alveolar ridge argumentation”[MeSH], and “systematic review”.
Data extraction and quality assessment
For each systematic review included, the following data were extracted: authors, year of publication, research question/objective, number of studies included, outcome measures, and journal of publication. Data extraction was performed in duplicate by the two authors/reviewers. To increase the accuracy and reduce the possibility of bias, the quality of the studies included was evaluated using two quality assessment tools: the AMSTAR guidelines and the checklist proposed by Glenny et al. The AMSTAR guidelines feature 11 items that are classified into four options: ‘1’ indicating ‘yes’, ‘2’ indicating ‘no’, ‘3’ indicating ‘cannot answer’, and ‘4’ indicating ‘not applicable’. Only option 1 (‘yes’) items generate the score. Therefore, each article could obtain a score between 0 (no criteria) and 11 (all criteria). There is no consensus on the scoring of the quality of the studies using the AMSTAR system. However, it has been proposed that studies with <3 points are low quality. The checklist proposed by Glenny et al. has 14 items, each with the same four options as the AMSTAR system. As with the AMSTAR, only option 1 (‘yes’) items generate the score.
The data collected using the two quality assessment tools were analyzed using descriptive statistics. The mean, standard deviation, and median of the two analyses were calculated. In addition, a correlation analysis of the scores obtained with the two tools was performed using the Spearman correlation coefficient, with a 95% confidence interval (CI) and a statistical significance level of P < 0.05. All statistical analyses were performed using Excel (Mac 2011, version 14.0.0; Microsoft Corporation, Redmond, WA, USA) and StatPlus (Mac LE 2009, AnalystSoft Inc., Walnut, CA, USA).