Quality assessment of systematic reviews on alveolar socket preservation

Efficacy of alveolar ridge preservation with xenografts and resorbable socket sealing materials in the esthetic region: A systematic review with meta-analyses

AIM

The present systematic review aimed to identify and summarize the clinical, radiographic, and histological outcomes of alveolar ridge preservation using bone xenografts and absorbable sealing materials compared with spontaneous healing in the esthetic zone.

MATERIALS AND METHODS

Randomized clinical trials (RCTs) fulfilling specific eligibility criteria were included. Two review authors independently searched for eligible studies, extracted data from the published reports and performed the risk of bias assessment (RoB 2 tool). Study results were summarized using random effects meta-analyses.

RESULTS

Thirteen articles concerning 10 RCTs were included, involving a total of 357 participants. Most of studies were considered as "low" risk of bias. Meta-analyses indicated less horizontal (difference in means-MD = 1.88 mm; p < 0.001), vertical mid-buccal (MD = 1.84 mm; p < 0.001) and vertical mid-lingual (MD = 2.27 mm; p < 0.001) bone resorption in alveolar ridge preservation compared to spontaneous healing as assessed clinically. Bone changes assessed radiographically showed consistent results in terms of horizontal (at 1 mm: MD = 1.84 mm, p < 0.001), vertical mid-buccal (MD = 0.95 mm; p < 0.001) and mid-lingual (MD = 0.62 mm; p = 0.05) resorption. Part of the bone resorption in the spontaneous healing group was compensated by soft-tissues, since the observed differences between groups in linear ridge reduction evaluated through cast models superimposition were smaller (MD = 0.52 mm; p < 0.001).

CONCLUSIONS

Alveolar ridge preservation with xenogeneic bone substitutes and non-autogenous resorbable socket sealing materials is efficacious in reducing post-extraction bone and ridge changes in the esthetic region.

Alveolar ridge preservation: an overview of systematic reviews

The aim of this overview was to assess the methodological quality of systematic reviews of randomized clinical trials on alveolar ridge preservation after a tooth extraction. During March 2020, two independent reviewers performed an electronic search of the PubMed (MEDLINE), Scopus, Web of Science, and Cochrane Library databases to identify all relevant systematic reviews including randomized clinical trials on alveolar ridge preservation. A manual search of articles in renowned journals was also conducted. The methodological quality of the included reviews was determined using the AMSTAR-2 tool. From the 53 initially retrieved studies, 11 were finally included: three systematic reviews and eight systematic reviews with meta-analyses. The methodological quality of the included reviews was low or critically low. Higher quality clinical studies should be conducted prior to performing further reviews and these should meet the methodological requirements that are fundamental to this type of research.

Post-extraction dimensional changes: A systematic review and meta-analysis

AIM

To analyse the evidence pertaining to post-extraction dimensional changes in the alveolar ridge after unassisted socket healing.

MATERIALS AND METHODS

The protocol of this PRISMA-compliant systematic review (SRs) was registered in PROSPERO (CRD42020178857). A literature search to identify studies that fulfilled the eligibility criteria was conducted. Data of interest were extracted. Qualitative and random-effects meta-analyses were performed if at least two studies with comparable features and variables reported the same outcome of interest.

RESULTS

Twenty-eight articles were selected, of which 20 could be utilized for the conduction of quantitative analyses by method of assessment (i.e. clinical vs radiographic measurements) and location (i.e. non-molar vs molar sites). Pooled estimates revealed that mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed clinically in non-molar sites was 2.73 mm (95% CI: 2.36-3.11), 1.71 mm (95% CI: 1.30-2.12) and 1.44 mm (95% CI: 0.78-2.10), respectively. Mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed radiographically in non-molar sites was 2.54 mm (95% CI: 1.97-3.11), 1.65 mm (95% CI: 0.42-2.88) and 0.87 mm (95% CI: 0.36-1.38), respectively. Mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed radiographically in molar sites was 3.61 mm (95% CI: 3.24-3.98), 1.46 mm (95% CI: 0.73-2.20) and 1.20 mm (95% CI: 0.56-1.83), respectively.

CONCLUSION

A variable amount of alveolar bone resorption occurs after unassisted socket healing depending on tooth type.

Combination of bone graft and resorbable membrane for alveolar ridge preservation: A systematic review, meta-analysis, and trial sequential analysis

INTRODUCTION

Alveolar ridge preservation (ARP) techniques aim to reduce resorption after tooth extraction. The combination of a graft material covered with a resorbable membrane represents one of the most common strategies performed in the clinical practice. The aim of this systematic review is to analyze evidence regarding potential benefits of ARP procedures performed with allogenic/xenogenic grafts in combination with a resorbable membrane coverage in comparison with spontaneous healing.

METHODS

Electronic databases were screened independently to select studies suitable for inclusion in this review. Horizontal ridge width reduction (HRWR) and vertical ridge height reduction (VRHR) were investigated as primary outcomes and volume changes (VC) as a secondary outcome. Meta-analysis was performed using the inverse of variance test with a random effect model. Adjustment for Type I and II errors and analysis of the power of evidence was performed with trial sequential analysis (TSA).

RESULTS

Seven studies met the inclusion criteria and were included in the quantitative synthesis. Meta-analysis revealed that the combination therapy resulted in a lower rate of resorption for both HRWR (-2.19 mm, 95% confidence interval [CI]: -2.67 to -1.71 mm) and VRHR (-1.72 mm, 95% CI: -2.14 to -1.30 mm). For VC no meta-analysis was performed due to insufficient data. Analysis of the power of the evidence performed with TSA showed that the number of both studies and sockets analyzed is sufficient to validate such findings, despite the high rate of heterogeneity.

CONCLUSIONS

Use of bone graft covered by a resorbable membrane can decrease the rate of alveolar ridge horizontal and vertical resorption after tooth extraction. The power and reliability of the evidence is strong enough to confirm the above-mentioned findings, despite the high rate of heterogeneity of included studies.

Quality assessment of systematic reviews on vertical bone regeneration

The aim of this study was to evaluate and compare the quality of systematic reviews of vertical bone regeneration techniques, using two quality-assessment tools (AMSTAR and ROBIS). An electronic literature search was conducted to identify systematic reviews or meta-analyses that would evaluate at least one of the following outcomes: implant survival, success rates, complications or bone gain after vertical ridge augmentation. Methodological quality assessment was performed by two independent evaluators. Results were compared between reviewers, and reliability measures were calculated using the Holsti's method^® and Cohen's kappa. Seventeen systematic reviews were included, of which seven presented meta-analysis. Mean ±95% confidence interval AMSTAR score was 6.35 [4.74;7.97], with higher scores being correlated with a smaller risk of bias (Pearson's correlation coefficient=-0.84; P<0.01). Cohen's inter-examiner kappa showed substantial agreement for both checklists. From the available evidence, we ascertained that, regardless of the technique used, it is possible to obtain vertical bone gains. Implant success in regenerated areas was similar to implants placed in pristine bone with results equating between 61.5% and 100% with guided bone regeneration being considered the most predictable technique regarding bone stability, while distraction osteogenesis achieved the biggest bone gains with the highest risk of possible complications.

Alveolar ridge preservation using a non-resorbable membrane: randomized clinical trial with biomolecular analysis

The aim of this randomized clinical trial was to evaluate the newly formed tissues in post-extraction sockets and to compare ridge dimensional changes with and without the use of a dense polytetrafluoroethylene membrane (d-PTFE). Twenty human extraction sockets (lower molars and premolars) received either an intentionally exposed d-PTFE membrane (test group) or no biomaterial (control group). After 4 months, during preparation for implant placement, bone and gingival tissues were collected for histological and biomolecular analysis. Clinically, the test and control groups showed mean gains of keratinized gingiva of 4.30±1.20mm and 2.50±2.20mm, respectively. A reduction in ridge width was observed in the control (2.90±2.70mm) and test (3.30±2.00mm) groups. The bone height alteration ranged from a reduction of 0.12±1.60mm to a gain of 0.60±3.60mm on average for both groups. Analysis of gene expression (OPG/RANKL) in gingival fibroblasts and osteoblasts revealed no difference between the two groups. Ridge preservation using the d-PTFE membrane increased the formation of keratinized tissue. A reduction in width and mild reduction/gain in height of the alveolar ridge was observed in both groups. The membrane had no influence on the healing process.

Methodological and Reporting Quality of Systematic Reviews and Meta-analyses in Endodontics

INTRODUCTION

The aim of this systematic review (SR) was to evaluate the quality of SRs and meta-analyses (MAs) in endodontics.

METHODS

A comprehensive literature search was conducted to identify relevant articles in the electronic databases from January 2000 to June 2017. Two reviewers independently assessed the articles for eligibility and data extraction. SRs and MAs on interventional studies with a minimum of 2 therapeutic strategies in endodontics were included in this SR. Methodologic and reporting quality were assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR) and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA), respectively. The interobserver reliability was calculated using the Cohen kappa statistic. Statistical analysis with the level of significance at P < .05 was performed using Kruskal-Wallis tests and simple linear regression analysis.

RESULTS

A total of 30 articles were selected for the current SR. Using AMSTAR, the item related to the scientific quality of studies used in conclusion was adhered by less than 40% of studies. Using PRISMA, 3 items were reported by less than 40% of studies, which were on objectives, protocol registration, and funding. No association was evident comparing the number of authors and country with quality. Statistical significance was observed when quality was compared among journals, with studies published as Cochrane reviews superior to those published in other journals. AMSTAR and PRISMA scores were significantly related.

CONCLUSIONS

SRs in endodontics showed variability in both methodologic and reporting quality.

Alveolar bone repair with strontium- containing nanostructured carbonated hydroxyapatite

Objective

This study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA) and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA) as bone substitute materials.

Methods

Twenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group). After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance.

Results

The histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05). We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039) in both groups.

Conclusion

The CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.

Use of platelet-rich fibrin in regenerative dentistry: a systematic review

OBJECTIVES

Research across many fields of medicine now points towards the clinical advantages of combining regenerative procedures with platelet-rich fibrin (PRF). This systematic review aimed to gather the extensive number of articles published to date on PRF in the dental field to better understand the clinical procedures where PRF may be utilized to enhance tissue/bone formation.

MATERIALS AND METHODS

Manuscripts were searched systematically until May 2016 and separated into the following categories: intrabony and furcation defect regeneration, extraction socket management, sinus lifting procedures, gingival recession treatment, and guided bone regeneration (GBR) including horizontal/vertical bone augmentation procedures. Only human randomized clinical trials were included for assessment.

RESULTS

In total, 35 articles were selected and divided accordingly (kappa = 0.94). Overall, the use of PRF has been most investigated in periodontology for the treatment of periodontal intrabony defects and gingival recessions where the majority of studies have demonstrated favorable results in soft tissue management and repair. Little to no randomized clinical trials were found for extraction socket management although PRF has been shown to significantly decrease by tenfold dry sockets of third molars. Very little to no data was available directly investigating the effects of PRF on new bone formation in GBR, horizontal/vertical bone augmentation procedures, treatment of peri-implantitis, and sinus lifting procedures.

CONCLUSIONS

Much investigation now supports the use of PRF for periodontal and soft tissue repair. Despite this, there remains a lack of well-conducted studies demonstrating convincingly the role of PRF during hard tissue bone regeneration. Future human randomized clinical studies evaluating the use of PRF on bone formation thus remain necessary.

CLINICAL RELEVANCE

PRF was shown to improve soft tissue generation and limit dimensional changes post-extraction, with little available data to date supporting its use in GBR.

Absorbable collagen sponges loaded with recombinant bone morphogenetic protein 9 induces greater osteoblast differentiation when compared to bone morphogenetic protein 2

The use of growth factors for the regeneration of soft and hard tissues has been utilized extensively in dental medicine over the past decade. Recently our group found that recombinant human bone morphogenetic protein 9 (rhBMP9) was more osteopromotive than recombinant human bone morphogenetic protein 2 (rhBMP2) when combined with a deprotenized bovine bone mineral bone grafting material. The aim of the present in vitro study was to evaluate the regenerative potential of an absorbable collagen sponge(ACS) specifically designed for extraction socket healing loaded with rhBMP9 when compared to rhBMP2. The adsorption and release kinetics of rhBMP2 and rhBMP9 were first investigated by enzyme-linked immunosorbent assay quantification. Then, the cellular effects of stromal cell line (ST2) preosteoblasts were investigated utilizing four groups including rhBMP2 and rhBMP9 at both low(10 ng/ml) and high(100 ng/ml) concentrations loaded onto ACS. Cellular attachment(8 hours) and proliferation(1, 3, and 5 days) as well as osteoblast differentiation were investigated by real-time polymerase chain reaction (PCR) at 3 and 14 days, alkaline phosphatase (ALP) activity at 7 days, and alizarin red staining at 14 days. ACS fully adsorbed both rhBMP2 and rhBMP9 that were slowly released up to 10 days. Although neither rhBMP2 nor rhBMP9 had any effects on cell attachment or proliferation, pronounced effects were observed on osteoblast differentiation. ALP activity was increased seven-fold with rhBMP2-high, whereas a marked 10-fold and 20-fold increase was observed with rhBMP9-low and high loaded to ACS, respectively. Furthermore, mRNA levels of collagen1, ALP, bone sialoprotein, and osteocalcin were all significantly higher for rhBMP9 when compared to control or rhBMP2 groups. Alizarin red staining further confirmed that rhBMP9-low and high demonstrated marked increases in mineralization potential when compared to rhBMP2-high. The results demonstrate the marked effect of rhBMP9 on osteoblast differentiation when combined with ACS in comparison to rhBMP2 at doses as much as 10 times lower. Further in vivo studies are necessary to investigate whether the regenerative potential is equally as potent.

Osteogain® loaded onto an absorbable collagen sponge induces attachment and osteoblast differentiation of ST2 cells in vitro

OBJECTIVES

Dimensional changes of the alveolar bone following tooth extraction are a major challenge in daily dental practice. To limit bone loss, a variety of biomaterials including bone grafts, barrier membranes, and growth factors have been utilized either alone or in combination therapies to increase the speed and quality of new bone formation. The aim of the present in vitro study was to investigate the regenerative potential of Osteogain®, a new liquid carrier system of enamel matrix derivative (EMD) in combination with an absorbable collagen sponge (ACS) specifically designed for extraction socket healing.

MATERIALS AND METHODS

The potential of ACS was first investigated using ELISA to quantify total amelogenin adsorption and release from 0 to 10 days. Thereafter, the cellular effects of ST2 pre-osteoblasts were investigated for cellular attachment at 8 h and cell proliferation at 1, 3, and 5 days as well as osteoblast differentiation by real-time PCR and alizarin red staining for cells seeded on (1) tissue culture plastic, (2) ACS alone, and (3) ACS + Osteogain®.

RESULTS

ACS efficiently loaded nearly 100% of the amelogenin proteins found in Osteogain® which were gradually released up to a 10-day period. Osteogain® also significantly induced a 1.5-fold increase in cell attachment and resulted in a 2-6-fold increase in mRNA levels of osteoblast differentiation markers including runt-related transcription factor 2 (Runx2), collagen1a2, alkaline phosphatase, and bone sialoprotein as well as induced alizarin red staining when combined with ACS.

CONCLUSIONS

In summary, these findings suggest that Osteogain® is capable of inducing osteoblast attachment and differentiation when combined with ACS. Future animal studies and randomized human clinical trials are necessary to further support these findings.

CLINICAL RELEVANCE

The use of Osteogain® in combination with ACS may provide a valuable means to limit dimensional changes following tooth extraction.