Quality assessment of systematic reviews on alveolar ridge preservation

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Quality assessment of systematic reviews on alveolar ridge preservation Juan G. De Buitrago, DDS; Gustavo Avila-Ortiz, DDS, MS, PhD; Satheesh Elangovan, BDS, DSc, DMSc

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lveolar ridge volume reduction is a direct consequence of tooth loss.1,2 This dimensional change occurs mainly at the expense of bone remodeling.3,4 The limited amount of remaining bone volume may compromise conventional implant placement and, subsequently, the functional and esthetic rehabilitation of the edentulous span. In an attempt to minimize postextraction dimensional changes, clinicians may use alveolar ridge preservation (ARP) techniques immediately after tooth extraction.5-7 A variety of surgical approaches and biomaterials have been proposed, including the use of autologous bone, allografts, xenografts, alloplastic materials, barrier membranes and growth factors.8,9 Although ARP has been investigated and debated, a consensus on the ideal clinical protocol has not been reached.10 This limitation may be a result of the fact that there are a number of local and systemic variables that may affect the clinical outcomes, as well as that there are marked methodological differences among most published studies. Therefore, analysis of the information available in the scientific literature may involve a significant amount of time and effort on the

AB STRACT Background. The authors conducted a study to assess the quality of systematic reviews (SRs) published on the topic of alveolar ridge preservation (ARP). Types of Studies Reviewed. The authors conducted a search for SRs on ARP on the basis of a set of eligibility criteria (only SRs involving ARP, with or without meta-analyses, written in English). The authors assessed the quality of the SRs independently of one another by using two established checklists. Results. The authors selected eight SRs. The results of all of the SRs indicated that ARP was effective in preserving the ridge volume as compared with extraction alone, but it did not fully prevent bone-resorptive events. None of the SRs, however, received the highest possible score in either of the checklists. One SR that had a score of 5 (of a possible 11) using one checklist and 5 (of a possible 14) using the other checklist had the lowest overall score. The results of this assessment revealed that a significant proportion of the investigators in the SRs did not include non– English language articles, perform hand searching of published literature or evaluate the gray literature. Assessment of publication bias and reporting of conflicts of interest also was lacking in some studies. Practical Implications. Although ARP appears to be an effective approach to preventing resorption after tooth extraction, significant structural and methodological variability exists among SRs on this topic. Future SRs on ARP should consider the use of quality assessment checklists to minimize methodological shortcomings for better dissemination of scientific evidence. Key Words. Alveolar ridge preservation; tooth extraction; systematic reviews; evidence-based medicine; evidence-based dentistry. JADA 2013;144(12):1349-1357.

Dr. De Buitrago is a visiting scholar, Department of Periodontics, College of Dentistry, The University of Iowa, Iowa City. Dr. Avila-Ortiz is an assistant professor, Department of Periodontics, College of Dentistry, The University of Iowa, 801 Newton Rd., Iowa City, Iowa 52242, e-mail [email protected]. Address reprint requests to Dr. Avila-Ortiz. Dr. Elangovan is an assistant professor, Department of Periodontics, College of Dentistry, The University of Iowa, Iowa City.

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part of clinicians who are interested in gaining specific knowledge on this topic. One way to simplify this task is to read a compilation of information obtained from individual studies in the form of a systematic review (SR), with or without concomitant metaanalyses. This type of study generally is acknowledged as the highest level of evidence and, therefore, is expected to focus on answering a specific, clinically relevant question and to present reliable information with scientific rigor.11 However, the conclusions and clinical recommendations from SRs regarding a specific topic may not show a high level of evidence owing to methodological or reporting inadequacies. This is the fundamental reason why guidelines and checklists to measure the quality of SRs have been created.12 Such tools are aimed primarily at helping clinicians critically assess the available SRs on a particular topic and may provide information about their limitations, which may aid future efforts to produce improved SRs. We conducted a study to assess the quality of SRs involving ARP. METHODS

Inclusion criteria and search strategy. To perform our quality assessment, we included only SRs regarding ARP, with or without metaanalyses, written in English. We included SRs that focused on the question of whether ARP was clinically efficacious in minimizing ridge resorption after tooth extraction. We excluded descriptive reviews or SRs that included preclinical studies. One of the authors (J.G.D.) conducted an initial search by searching for the phrases “human studies,” “English” and “systematic reviews” in three databases (Thomson Reuters Web of Knowledge, SciVerse/Scopus and PubMed). This search included all published studies through July 2013 with no restriction in publication dates. The author used the key words “ridge preservation,” “alveolar ridge preservation,” “socket preservation” and “socket grafting” independently in each of the three databases for a total of 12 entry lists. In addition, he searched the American Dental Association Center for Evidence-Based Dentistry’s (ADA EBD) systematic review database in July 2013 for SRs on ARP. This author also hand searched 10 scientific journals (Journal of Dental Research, Journal of Periodontology, Journal of Clinical Periodontology, Clinical Oral Implants Research, The International Journal of Oral and Maxillofacial Implants, Clinical Implant Dentistry and Related Research, Implant Dentistry, The International Journal of Periodontics

and Restorative Dentistry, The International Journal of Oral and Maxillofacial Surgery, and European Journal of Oral Implantology) for articles published from January 1999 through July 2013. After generating an initial list of entries, we performed an initial screening of titles and abstracts. As shown in the figure, we reviewed in full the articles selected after the initial screening, excluding duplicates. In those cases in which there were doubts about the inclusion of a study, consensus was reached by means of open discussion. Examining and scoring the SRs. We conducted a quality assessment of the SRs by using two checklists. One was the Assessment of Multiple Systematic Reviews12 (AMSTAR) checklist and the other one was the checklist devised by Glenny and colleagues.13 Each item on the checklists received a score ranging from 1 to 4 (in which 1 = yes, 2 = no, 3 = cannot answer and 4 = irrelevant). In our study, we excluded item K from Glenny and colleagues’13 checklist (“Are the results given in a narrative or pooled statistical analysis? [narrative, pooled, not applicable]”) from the assessment because the results were presented in a narrative or pooled format that was not indicative of whether an item was of higher or lower quality. We scored the SRs. We had conversations to reach agreement on those items to which we did not give consistent scores. Statistical methods. We calculated the interexaminer agreement rate on the basis of the initial assessments (those assessments that led to the original scores). We summed all items that had a score of 1 to obtain the total score for each study for both checklists. The highest score possible when the AMSTAR12 checklist was used was 11 and the lowest was 0, whereas the scores from Glenny and colleagues’13 checklist ranged from 0 to 14. We also calculated the mean and median values, as well as the standard deviation of all SRs, by using both checklists. RESULTS

Article selection. The database searches yielded the following results: we found 47 articles in PubMed, 212 in Thomson Reuters Web of Knowledge and 158 in SciVerse/Scopus (Figure). We found seven SRs on ARP in the ABBREVIATION KEY. ADA EBD: American Dental Association Center for Evidence-Based Dentistry. AMSTAR: Assessment of Multiple Systematic Reviews. ARP: Alveolar ridge preservation. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analysis. SR: Systematic review.

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Records identified through ADA EBD database (n = 7)

Records identified through Thomson Reuters Web of Knowledge (n = 212)

Records identified through PubMed (n = 47)

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Records identified through SciVerse/Scopus (n = 158)

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Records identified by means of hand searching (n = 10)

Records screened (excluding duplicates) (n = 150) Records excluded on the basis of title and abstract (n = 128)

Full-text articles assessed for eligibility (n = 22)

Full-text articles excluded (n = 14)

Studies selected for quality assessment (n = 8)

Figure. Flowchart showing the search process. ADA EBD: American Dental Association Center for Evidence-Based Dentistry.

ADA EBD’s database. In addition, we identified 10 articles by means of hand searching. After we excluded duplicate studies, the total number of articles selected after the initial screening was 150. After reviewing the titles and abstracts, we assessed the full text of 22 articles. We excluded 14 articles, leaving us with eight SRs8,14-20 for our quality assessment. Among the excluded studies, four did not deal exclusively with the topic of ARP.2,21-23 We excluded the remaining 10 articles because they were not proper SRs.9,10,24-31 Clinical relevance of the SRs. On the basis of the reported findings, we show the most significant content of the SRs in Table 1,8,14-20 including the outcomes assessed, the number of studies included in the SR, the research questions and the main conclusions. There was a consensus among the results of the SRs that ARP appears to be effective in preserving the alveolar ridge volume compared with extraction alone, but it also was generally acknowledged that ARP did not fully prevent bone resorption. Scores for the SRs and descriptive statistics. Table 28,14-20 (page 1354) shows the SRs and their corresponding AMSTAR12 and Glenny and colleagues13 checklist scores. The results of the quality assessment we conducted by using the AMSTAR12 checklist are summarized in Table 3 (page 1354). All SRs had an a priori design (item 1) and reported the characteristics of

their included studies (item 6). Three-quarters (75 percent) of the SRs reported that they used at least two independent examiners for study selection and data extraction (item 2), and the reviewers in the same percentage (75 percent) of SRs took the quality of the included studies into consideration while formulating their conclusions (item 8). Similarly, most SRs (87 percent) received a score of 1 in the assessment of items 3 (“Was a comprehensive literature search performed?”), 5 (“Was a list of studies [included and excluded] provided?”) and 7 (“Was the scientific quality of the included studies assessed and documented?”). Reviewers in only 25 percent of the SRs reported to have searched published and unpublished literature (item 4), and reviewers in the same percentage of SRs used appropriate methods to combine the findings of the studies (item 9). In the case of item 9, the remaining 75 percent of SRs received a score of 4, given the fact that a meta-analysis was performed in only two of the SRs. The reviewers in only one SR assessed the likelihood of publication bias (item 10). In only 63 percent of the SRs did the reviewers state conflict of interest (item 11). The scores derived from the quality assessment by using Glenny and colleagues’13 checklist are displayed in Table 4 (page 1355). Reviewers in all of the SRs reported having addressed a focused question (item A) and presented the JADA 144(12) http://jada.ada.org December 2013 1351

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results clearly (item TABLE 1 M). Most of the SRs Summary of the most significant content of the (88 percent) received a score of 1 for items selected systematic reviews. B (“Did authors look AUTHOR, yEAR COUNTRy JOURNAL OUTCOMES ASSESSED for appropriate paOF ORIGIN NAME pers?”), C (“Do you The Soft- and hard-tissue healing and Del Fabbro and Italy think authors atInternational postoperative quality of life Colleagues, tempted to identify Journal of 2011 Oral and all relevant studies?”) Maxillofacial and H (“Did reviewSurgery ers attempt to assess Netherlands Clinical Oral Changes in bone height and width Ten the quality of the inImplants Heggeler and Research Colleagues, cluded studies?”). Re2011 viewers in only onefourth (25 percent) of the SRs satisfied Germany European Changes in bone height and width and Weng and items D (“Search for Journal of Oral need for additional grafting Colleagues, published and unpubImplantology 2011 lished literature?”), L (“If the results have United Clinical Implant Clinical, radiographic, histologic and Morjaria and Kingdom Dentistry patient-centered outcomes (that is, Colleagues, been combined, was it and Related incidence of complications) 2012 reasonable to do so?”) Research and N (“Was an asSpain Clinical Oral The primary outcome was bone Vignoletti and Implants dimensional changes; multiple secondary sessment of heteroColleagues, Research outcomes were considered including 2012 geneity made and soft-tissue dimensional changes, amount reasons for variation of keratinized tissue, changes in clinical attachment levels, availability of bone discussed?”). Of the and the need for additional grafting at SRs, reviewers in the time of implant placement 75 percent of them satisfied items G United The Histomorphometric Chan and States International Colleagues, (“Was it stated that Journal of 2013 the inclusion criteria Oral and were carried out by Maxillofacial Implants at least two reviewers?”), I (“If so, did they include this in Hungary, Clinical Oral The primary outcome was the change in Horváth and United Investigations orofacial (horizontal) and apicocoronal Colleagues, the analysis?”) and Kingdom, (vertical) alveolar ridge dimensions; 2013 O (“Were results of Brazil multiple secondary outcomes were review interpreted considered, including changes in buccal plate thickness, bone volume alteration, appropriately?”). incidence of complications and histologic Regarding items E healing characteristics (“Were all languages Italy The Changes in alveolar bone height and Vittorini considered?”) and J International width Orgeas and Journal of Oral Colleagues, (“Was it stated that Maxillofacial 2013 the quality assessImplants ment was carried out by at least two SRs was 7.375 (1.407) (of a possible 11), while reviewers?”), 37 percent of the SRs received a the median was 7.5. On the other hand, both the score of 1. Finally, 63 percent of the SRs satismean (SD) score of all SRs using the checklist defied item F (“Was any hand searching carried vised by Glenny and colleagues13 was 9 (2.507) (of out?”). a possible 14), with a median of 9. We found an initial agreement of 78 between the scores of the authors who assessed the SRs DISCUSSION independently of one another, which is indicative The best available research evidence, which is of a good interexaminer consistency. The mean the most objective domain of evidence-based (standard deviation [SD]) AMSTAR score of all 14

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a critical analysis of multiple studies.33 Although a theoretical systematic approach and other stringent INCLUDED RESEARCH QUESTION MAIN CONCLUSIONS strategies typically STUDIES, NO. are used to conduct 8 Does the use of autologous platelet The use of platelet concentrates may be SRs, variability exists concentrates improve the healing of beneficial for reducing postoperative among SRs, which extraction sockets? pain and inflammation, thereby makes the search for improving quality of life in the early period after extraction a solid conclusion to a clinical question chal9 What is the effect of ridge Ridge preservation may aid in reducing lenging and somepreservation therapies in patients the bone dimensional changes after who received tooth extraction in tooth extraction; however, it does not times even confusing the anterior and premolar region fully prevent bone resorption or misguided. in comparison with no additional We conducted this treatment with respect to bone height and width? study to assess the 10 Are ridge preservation techniques Ridge preservation seems to be effective quality of published efficient in maintaining alveolar to maintain ridge dimensions after tooth SRs that focused on ridges after tooth extraction or not? extraction; no recommendations for a the clinical efficacy specific technique or material were given of ARP postextrac9 Is there any benefit in bone grafting Socket intervention therapies did reduce and/or guided bone regeneration alveolar ridge dimensional changes tion. The results of in the management of extraction postextraction but were unable to fully our assessment, in sockets? prevent resorption which we used two 9 Do ridge preservation therapies Although some degree of bone checklists, revealed a improve the outcomes of the remodeling will occur after tooth different rehabilitation approaches extraction, different ridge preservation marked methodologiafter tooth loss? procedures resulted in significantly less cal and structural vertical and horizontal contraction of the alveolar bone variability among the SRs. Compared with previous assessments of SRs on other top8 What was the effect of ridge The application of grafting materials for preservation procedures using ridge preservation might have a positive ics in periodontology different grafting materials on bone influence on vital bone formation and oral implantolquality, defined as the composition ogy published by our of new bone, connective tissue and residual grafting materials, and how group,34-36 the overall did it compare with the effect of quality of the SRs in natural socket healing? this study was high. 14 After tooth or root extraction, what Postextraction resorption of the alveolar This finding may be is the effect of ridge preservation on ridge might be limited, but cannot be the residual alveolar ridge dimension completely eliminated by alveolar ridge due to the fact that and on histologic characteristics, preservation the SRs in our study compared with unassisted socket healing? were published recently (during the period from 2011 13 What are the dimensional changes of Ridge preservation procedures seem to through 2013).8,14-20 It the extraction socket after different be effective in limiting horizontal and surgical techniques for alveolar ridge vertical ridge alterations after tooth is likely that authors’ preservation? extraction increased awareness about the existing checklists and jourmedicine and dentistry, heavily relies on wellnals’ stringent reporting requirements have conducted SRs and meta-analyses.32 This type positively influenced the quality of the SRs. of research evidence is expected to provide ARP by means of socket grafting is a therapeuvaluable information that may help the clinitic approach that, although it was first proposed cal community develop predictable protocols to in the 1980s,37,38 has gained popularity since guide daily practice. Clinicians, researchers and 2000. A direct consequence is that as of today, policymakers seek out SRs to find recommendathere is a low number of well-conducted clinical tions on a particular topic of interest that are trials involving this topic that meet the includerived from comprehensive data extraction and sion criteria in most SRs. In addition, the nar-

TABLE 1 (CONTINUED)

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ing similar trials is high. But, in our opinion, this should not be a Included systematic reviews and reason for ignoring the array of corresponding AMSTAR*† and Glenny quality levels among the SRs. The fact that SRs with different levels and colleagues‡ checklist scores. of quality yield similar concluAuthor, year AMSTAR Glenny and sions in the topic of ARP may not Checklist colleagues score checklist score be true in other areas of dentistry, (11 items) (14 items) especially those that deal with 9 12 Del Fabbro and Colleagues, 2011 controversial topics (for example, 7 9 Ten Heggeler and Colleagues, 2011 the periodontitis-systemic disease 5 5 Weng and Colleagues, 2011 connection).34 7 9 Morjaria and Colleagues, 2012 ARP is a broad term that 9 12 Vignoletti and Colleagues, 2012 encompasses a wide variety of 6 6 techniques that use different maChan and Colleagues, 2013 terials to preserve the alveolar 8 10 Horváth and Colleagues, 2013 bone volume after tooth extraction. 8 9 Vittorini Orgeas and Colleagues, 2013 We noticed variations in the SRs * AMSTAR: Assessment of Multiple Systematic Reviews. regarding outcome variables (both † Source: Shea and colleagues. primary and secondary) and the ‡ Source: Glenny and colleagues. intervals for postintervention outtable 3 comes assessment. Although the reviewers in most of the SRs14-20 AMSTAR*† checklist and the number (%) considered dimensional changes of studies that satisfied each of the in ridge width and height as the checklist items. primary outcome, other secondary outcomes (such as soft-tissue Item No. (%) of studies AMSTAR Checklist item No. healing, postoperative quality Yes No Cannot Irrelevant Answer of life and histologic outcomes) Was an “a priori” design 8 (100) 0 (0) 0 (0) 0 (0) were considered in a few SRs.8,14,18 1 provided? Therefore, aside from presentWas there duplicate study 6 (75) 2 (25) 0 (0) 0 (0) 2 ing the main findings of each SR selection and data extraction? (Table 18,14-20) and analyzing the Was a comprehensive literature 7 (87) 1 (13) 0 (0) 0 (0) 3 methodological quality, we did search performed? not attempt to conduct any parWas the status of publication 2 (25) 6 (75) 0 (0) 0 (0) 4 (that is, gray literature) used as ticular pooled outcome analyses an inclusion criterion? of the SRs, since it was not methWas a list of studies (included 7 (87) 1 (13) 0 (0) 0 (0) 5 odologically possible and it was and excluded) provided? not within the scope of our study. Were the characteristics of the 8 (100) 0 (0) 0 (0) 0 (0) 6 However, considering the concluincluded studies provided? sions of the SRs that we found Was the scientific quality of the 7 (87) 1 (13) 0 (0) 0 (0) 7 included studies assessed and to be high quality on the basis of documented? their AMSTAR12 and Glenny and Was the scientific quality of 6 (75) 2 (25) 0 (0) 0 (0) 8 colleagues13 checklist scores that the included studies used were published on this topic, ARP appropriately in formulating conclusions? appears to be effective in preservWere the methods used to 2 (25) 0 (0) 0 (0) 6 (75) 9 ing the alveolar ridge volume combine the findings of studies compared with extraction alone, appropriate? but it does not fully prevent bone Was the likelihood of 1 (13) 6 (74) 1 (13) 0 (0) 10 resorption.18-20 publication bias assessed? Our assessment using the Was the conflict of interest 5 (63) 3 (37) 0 (0) 0 (0) 11 stated? AMSTAR12 checklist revealed * AMSTAR: Assessment of Multiple Systematic Reviews. that two items (“Was an ‘a priori’ † Source: Shea and colleagues. design provided?” [item 1]; “Were rower the range for year of publication in an SR, the characteristics of the included studies prothe more similar the conclusions of the reviews vided?” [item 6]) were addressed in all of the are expected to be, as the possibility of includSRs, while one item (“Was the likelihood of pubtable 2

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table 4 lication bias assessed?” [item 10]) was considered in only one SR18 Glenny and colleagues* checklist items and (Table 312). We also observed that the number (%) of studies that satisfied only a few SRs14,20 included items 4 (inclusion of gray literature) and each of the checklist items. 11 (reporting conflict of interest). Item Glenny and colleagues No. (%) of studies (Gray literature refers to materiChecklist item† Yes No Cannot Irrelevant als that cannot be found through Answer conventional searching channels, Did reviewer address a focused 8 (100) 0 (0) 0 (0) 0 (0) A such as published studies in peerquestion? review journals, and may include Did authors look for 7 (88) 1 (12) 0 (0) 0 (0) B appropriate papers? government research, nonprofit Do you think authors attempted 7 (88) 1 (12) 0 (0) 0 (0) C reports, think tank assessments, to identify all relevant studies? reports from observations, indeSearch for published and 2 (25) 6 (75) 0 (0) 0 (0) D pendent investigations and other unpublished literature? 39 primary resource materials. ) ReWere all languages considered? 3 (37) 5 (63) 0 (0) 0 (0) E viewers conducted meta-analyses Was any hand searching carried 5 (63) 2 (25) 1 (12) 0 (0) F 18,20 only in two SRs. (When data out? pooling is performed by means of Was it stated that the inclusion 6 (75) 2 (25) 0 (0) 0 (0) G criteria were carried out by at a meta-analysis, the analysis of least two reviewers? the homogeneity of the articles Did reviewers attempt to assess 7 (88) 1 (12) 0 (0) 0 (0) H using statistical tests, such as the the quality of the included 2 c test, is crucial.) We found that studies? reviewers performed a test for hoIf so, did they include this in the 6 (75) 2 (25) 0 (0) 0 (0) I analysis? mogeneity in both of these SRs.8,20 Was it stated that the quality 3 (37) 4 (50) 1 (12) 0 (0) J‡ Because investigators in a limited assessment was carried out by at 14,18,19 number of SRs reported the least two reviewers? results of meta-analyses, we conIf the results have been 2 (25) 0 (0) 0 (0) 6 (75) L sidered item 9 irrelevant for six combined, was it reasonable to 14-17,19,20 do so? of the SRs. The results of Are the results clearly displayed? 8 (100) 0 (0) 0 (0) 0 (0) M our assessment using Glenny and 13 Was an assessment of 2 (25) 0 (0) 0 (0) 6 (75) N colleagues’ checklist pointed out heterogeneity made and that the authors in three SRs14,18,19 reasons for variation discussed? searched for studies without lanWere results of review 6 (75) 2 (25) 0 (0) 0 (0) O guage restrictions, those in two interpreted appropriately? SRs14,20 searched published and * Source: Glenny and colleagues. † Adapted with permission of John Wiley and Sons from Glenny and colleagues. unpublished data (gray litera‡ The percentages in this row do not total 100 percent owing to rounding. ture), and those in three SRs14,15,17 reported having more than one examiner assess the quality of the included tion bias may be a serious threat to the validity trials (Table 413). of the recommendations presented in an SR, On the basis of our findings, we recommend meta-analysis or both. that future SRs involving this topic focus on the Although AMSTAR12 is a validated tool for following components: inclusion of articles in assessing the quality of SRs, it fails to produce all languages, hand searching, inclusion of gray a quantifiable assessment of SR quality. For literature, assessment of publication bias and example, it is not possible to rate the quality of reporting of conflict of interest. The first three SRs on the basis of whether bias was prevented components are related to how comprehensive in the included studies by using AMSTAR. the search is. Inclusion of data from the gray There is no one checklist that covers all aspects literature can add to the quality and quantity of of a good-quality SR. For that reason, we used pertinent information from SRs. Assessment of two checklists to perform the quality assesspublication bias also is important. Publication ment. We conducted our study to assess the bias tests are used to assess whether studies quality of reviews as they were published and and trials addressing the focused question were reported. Therefore, it is possible that authors conducted but not published for reasons such as could have performed a particular assessment negative results, study sponsors’ preferences or (for example, test for homogeneity or publicathe power of the trial.40 Not assessing publication bias), but the results may not have been 13

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reported in the final publication. Using specific guidelines such as AMSTAR or Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) (which is required by The Journal of the American Dental Association41) when designing and conducting SRs may increase the validity and clinical applicability of future SRs.12,42 Implementation by all peer-reviewed journals of such quality assessment guidelines for evaluating SRs and metaanalyses also may contribute toward providing the dental community with better scientific literature. Clinicians should be aware that there are discrepancies in the quality of scientific evidence and be familiar with appraisal tools such as AMSTAR,12 PRISMA42 or Strength of Recommendation Taxonomy guidelines.43 CONCLUSIONS

Significant structural and methodological variability exists among SRs involving the efficacy of ARP. None of the eight SRs in our study received a score of 1 for all of the AMSTAR12 or Glenny and colleagues13 checklist items. Using specific guidelines such as AMSTAR12 or PRISMA12 when designing and conducting SRs may increase the validity and clinical applicability of future SRs. Specifically, investigators in future SRs involving ARP should improve the quality of the search strategy by including non–English-language articles, hand searching of published literature and evaluating the gray literature. Reporting publication bias and conflict of interest also should be a priority for future SRs. n Disclosure. None of the authors reported any disclosures. 1. Van der Weijden F, Dell’Acqua F, Slot DE. Alveolar bone dimensional changes of post-extraction sockets in humans: a systematic review. J Clin Periodontol 2009;36(12):1048-1058. 2. Tan WL, Wong TL, Wong MC, Lang NP. A systematic review of post-extractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res 2012;23(suppl 5):1-21. 3. Araújo MG, Lindhe J. Dimensional ridge alterations following tooth extraction: an experimental study in the dog. J Clin Periodontol 2005;32(2):212-218. 4. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent 2003;23(4):313-323. 5. Barone A, Ricci M, Tonelli P, Santini S, Covani U. Tissue changes of extraction sockets in humans: a comparison of spontaneous healing vs. ridge preservation with secondary soft tissue healing (published online ahead of print July 12, 2012). Clin Oral Implants Res 2012. doi:10.1111/j.1600-0501.2012.02535.x. 6. Cardaropoli D, Tamagnone L, Roffredo A, Gaveglio L, Cardaropoli G. Socket preservation using bovine bone mineral and collagen membrane: a randomized controlled clinical trial with histologic analysis. Int J Periodontics Restorative Dent 2012;32(4):421-430. 7. Iasella JM, Greenwell H, Miller RL, et al. Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: a clinical and histologic study in humans. J Periodontol 2003;74(7):990-999. 8. Chan HL, Lin GH, Fu JH, Wang HL. Alterations in bone qual-

ity after socket preservation with grafting materials: a systematic review. Int J Oral Maxillofac Implants 2013;28(3):710-720. 9. Darby I, Chen ST, Buser D. Ridge preservation techniques for implant therapy. Int J Oral Maxillofac Implants 2009;24(suppl):260-271. 10. Horowitz R, Holtzclaw D, Rosen PS. A review on alveolar ridge preservation following tooth extraction. J Evid Based Dent Pract 2012;12(3 suppl):149-160. 11. Rosner AL. Evidence-based medicine: revisiting the pyramid of priorities. J Bodyw Mov Ther 2012;16(1):42-49. 12. Shea BJ, Bouter LM, Peterson J, et al. External validation of a measurement tool to assess systematic reviews (AMSTAR) (published online Dec. 26, 2007). PLoS One 2007;2(12):e1350. doi:10.1371/journal.pone.0001350. 13. Glenny AM, Esposito M, Coulthard P, Worthington HV. The assessment of systematic reviews in dentistry. Eur J Oral Sci 2003;111(2):85-92. 14. Del Fabbro M, Bortolin M, Taschieri S. Is autologous platelet concentrate beneficial for post-extraction socket healing? A systematic review. Int J Oral Maxillofac Surg 2011;40(9):891-900. 15. Ten Heggeler JM, Slot DE, Van der Weijden GA. Effect of socket preservation therapies following tooth extraction in non-molar regions in humans: a systematic review. Clin Oral Implants Res 2011;22(8):779-788. 16. Weng D, Stock V, Schliephake H. Are socket and ridge preservation techniques at the day of tooth extraction efficient in maintaining the tissues of the alveolar ridge? Eur J Oral Implantol 2011;4(5):59-66. 17. Morjaria KR, Wilson R, Palmer RM. Bone healing after tooth extraction with or without an intervention: a systematic review of randomized controlled trials (published online ahead of print March 8, 2012). Clin Implant Dent Relat Res 2012. doi:10.1111/j.1708-8208. 2012.00450.x. 18. Vignoletti F, Matesanz P, Rodrigo D, Figuero E, Martin C, Sanz M. Surgical protocols for ridge preservation after tooth extraction: a systematic review. Clin Oral Implants Res 2012;23(suppl 5):22-38. 19. Horváth A, Mardas N, Mezzomo LA, Needleman IG, Donos N. Alveolar ridge preservation: a systematic review. Clin Oral Investig 2013;17(2):341-363. 20. Vittorini Orgeas G, Clementini M, De Risi V, de Sanctis M. Surgical techniques for alveolar socket preservation: a systematic review. Int J Oral Maxillofac Implants 2013;28(4):1049-1061. 21. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement (published correction appears in Int J Oral Maxillofac Implants 2008;23[1]:56)? Int J Oral Maxillofac Implants 2007;22(suppl):49-70. 22. Fiorellini JP, Nevins ML. Localized ridge augmentation/preservation: a systematic review. Ann Periodontol 2003;8(1):321-327. 23. McAllister BS, Haghighat K. Bone augmentation techniques. J Periodontol 2007;78(3):377-396. 24. Agarwal G, Thomas R, Mehta D. Postextraction maintenance of the alveolar ridge: rationale and review. Compend Contin Educ Dent 2012;33(5):320-324, 326. 25. Allegrini S Jr, Koening B Jr, Allegrini MR, et al. Alveolar ridge sockets preservation with bone grafting: review. Ann Acad Med Stetin 2008;54(1):70-81. 26. Ashman A. Ridge preservation: important buzzwords in dentistry. Gen Dent 2000;48(3):304-312. 27. Block MS, Jackson WC. Techniques for grafting the extraction site in preparation for dental implant placement. Atlas Oral Maxillofac Surg Clin North Am 2006;14(1):1-25. 28. Kubilius M, Kubilius R, Gleiznys A. The preservation of alveolar bone ridge during tooth extraction. Stomatologija 2012;14(1):3-11. 29. Porrini R, Rocchetti V, Vercellino V, Cannas M, Sabbatini M. Alveolar bone regeneration in post-extraction socket: a review of materials to postpone dental implant. Biomed Mater Eng 2011;21(2):63-74. 30. Seibert JS, Salama H. Alveolar ridge preservation and reconstruction. Periodontol 2000 1996;11(1):69-84. 31. Yeo AB, Ong MM. Principles and implications of site preservation for alveolar ridge development. Singapore Dent J 2004;26(1): 15-20. 32. Abt E, Bader JD, Bonetti D. A practitioner’s guide to developing critical appraisal skills: translating research into clinical practice. JADA 2012;143(4):386-390. 33. McGlone P, Watt R, Sheiham A. Evidence-based dentistry: an overview of the challenges in changing professional practice. Br Dent J 2001;190(12):636-639. 34. Kelly JT, Avila-Ortiz G, Allareddy V, Johnson GK, Elangovan S.

1356 JADA 144(12) http://jada.ada.org December 2013 Copyright © 2013 American Dental Association. All Rights Reserved.

CLINICAL The association between periodontitis and coronary heart disease: a quality assessment of systematic reviews. JADA 2013;144(4):371-379. 35. Elangovan S, Mawardi HH, Karimbux NY. Quality assessment of systematic reviews on short dental implants. J Periodontol 2013;84(6):758-767. 36. Elangovan S, Avila-Ortiz G, Johnson GK, Karimbux N, Allareddy V. Quality assessment of systematic reviews on periodontal regeneration in humans. J Periodontol 2013;84(2):176-185. 37. Kentros GA, Filler SJ, Rothstein SS. Six month evaluation of particulate Durapatite in extraction sockets for the preservation of the alveolar ridge. Implantologist 1985;3(2):53-62. 38. Quinn JH, Kent JN, Hunter RG, Schaffer CM. Preservation of the alveolar ridge with hydroxylapatite tooth root substitutes. JADA 1985;110(2):189-193. 39. Conn VS, Valentine JC, Cooper HM, Rantz MJ. Grey literature

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