Choice of comparator in restorative trials: A network analysis

Systematic review and network meta-analysis of restorative therapy and adhesive strategies in root caries lesions

AIM

This systematic review and network meta-analysis (NMA) aimed to establish a clinically relevant hierarchy of the different adhesive and/or restorative approaches to restore cavitated root caries lesions through the synthesis of available evidence.

MATERIALS AND METHODS

A systematic search was conducted in Medline/Web of Science/Embase/ Cochrane Library/Scopus/grey literature. RCTs investigating ≥2 restorative strategies (restorative /adhesive materials) for root caries lesions in adult patients were included. Risk of bias within studies was assessed (Cochrane_RoB-2) and the primary outcome was survival rate of restorations at different follow-up times (6-/12-/24-months). Network meta-analyses were conducted using a random effects model stratified by follow-up times. I2-statistics assessed the ratio of true to total variance in the observed effects. All available combinations of adhesives (1-SE: one-step self-etch; 2-3ER: two-/three-step etch-and-rinse) and restorative materials (conventional composite (CC) as well as conventional and resin-modified glass ionomer cements (GIC, RMGIC)) were included. Risk of bias across studies and confidence in NMA (CINeMA) were assessed.

RESULTS

547 studies were identified and nine were eligible for the NMA. In total, 1263 root caries lesions have been restored in 473 patients in the included clinical trials. Patients involved were either healthy (n = 6 trials), living in nursing homes (n = 1 trial) or received head-and-neck radiotherapy (n = 2 trials). There was statistically weak evidence to favour either of material/material combination regarding the survival rate. A tendency for higher survival rate (24-months) was observed for 2-3ER/CC (OR24mths 2.65; 95%CI=1.45/4.84) as well as RMGIC (OR24mths 2.05; 95%CI=1.17/3.61) compared to GIC. These findings were though not statistically significant and confidence of the NMA was low.

CONCLUSION

An evidence-based choice of restorative strategy for managing cavitated root caries lesions is currently impossible. There is a clear need for more standardised, well-designed RCTs evaluating the retention rate of root caries restoration approaches.

Color Change Evaluation of Three Universal Resin Composites after Storage in Water: An In Vitro Study

Aim:

The aim of this in vitro study was to evaluate the color changes of three different universal resin composites after immersion in distilled water for one month.

Materials and Methods:

Omnichroma, Estelite Σ Quick, and Filtek Universal Restorative were investigated. Ten disk shaped specimens (6 mm diameter, 2 mm thickness) were prepared according to the manufacturers’ instructions for each material. After polishing, initial color measurements were taken followed by individual storage of the specimens in distilled water at 37 °C for one month when color measurements were repeated. The change in the color of each resin composites (Δ E00) was calculated with a digital method, using the CIEDE2000 color difference formula. The data were analyzed using one-way ANOVA followed by Tukey post-hoc test ( P < .05).

Results:

All resin composites exhibited acceptable color change after one month. Omnichroma exhibited the highest color change (2.26 ± 0.48) value while Filtek Universal Restorative showed the lowest (1.14 ± 0.38) value. All color parameters influenced the Δ E00 values in all groups except Filtek Universal for Δ L* and Δ b values.

Conclusion:

When performing composite resin restorations, especially for esthetic purposes, polymerization may lead to change in the color of restorative material over time, but it should be considered whether this is within acceptable limits.

Glass hybrid versus composite for non-carious cervical lesions: Survival, restoration quality and costs in randomized controlled trial after 3 years

OBJECTIVE

This study compared survival, restoration quality and costs of glass hybrid (GH; EQUIA Forte Fil/EQUIA Forte Coat) and resin composite restorations (RC; OptiBond FL/Filtek Supreme XTE) of sclerotic non-carious cervical lesions.

METHODS

This is a cluster-randomized trial (ClinicalTrials.gov: NCT02631161). 88 patients (50-70 years) with 175 sNCCLs were randomized to receive GH or RC. Restorations were placed without mechanical cavity preparation and followed for a mean 36 (min/max: 31/55) months (variable follow-up due to COVID-19 lockdown). Restoration quality was re-evaluated at 1-, 18- and 36-months using FDI-criteria. Survival was assessed using multi-level Cox-regression analysis. Costs were estimated from a payer's perspective in Germany. Initial costs were determined based on micro-costing using time recordings and hourly costs, and follow-up costs based on statutory insurance fee-item-catalogues.

RESULTS

88 patients (175 restorations) were treated; 43 received GH (83 restorations), 45 RC (92 restorations). 17  GH and 19 RC showed total retention loss, 5  GH were partially lost (p = 0.396/Cox). FDI ratings were not sufficiently different for any domain except surface luster, where RC showed higher score (p < 0.001). Costs were initially lower for GH (32.57; SD 16.36 €) than RC (44.25; SD 21.40 €), while re-treatment costs were similar (GH: 9.15; SD 15.70 €; RC: 7.35; SD 14.51 €), resulting in significantly lower costs for GH (GH: 41.72; SD 25.08 €) than RC (51.60; 26.17 €) (p < 0.001/GLM).

CONCLUSIONS

While survival was not significantly different, GH was significantly less costly both initially and long-term than RC for restoring non-carious cervical lesions.

CLINICAL SIGNIFICANCE

Within this trial, survival was not significantly different between GH and RC to restore sclerotic NCCLs. As GH was significantly less costly both initially and long-term than RC, using RC was only cost-effective for payers willing to invest high additional expenses per minimal survival gains.

Adhesive strategies in cervical lesions: systematic review and a network meta-analysis of randomized controlled trials

OBJECTIVES

A network meta-analysis (NMA) was performed to assess which adhesive strategy is most clinically effective in treating non-carious cervical lesions (NCCLs).

MATERIAL AND METHODS

Studies were identified by a systematic search of electronic databases including MEDLINE via PubMed, Brazilian Library in Dentistry (BBO), Cochrane Library, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), Scopus, and Web of Science without restrictions on publication year or language. The grey literature was also consulted. Only randomized clinical trials that compared different adhesive strategies in NCCLs in adult patients were included. The risk of bias was evaluated by using the Cochrane Collaboration tool. A random-effects Bayesian mixed treatment comparison model was used to compare adhesive strategies (3ER, 2ER, 2SE, and 1SE) at different follow-up times. The surface under cumulative ranking curve (SUCRA) was estimated for each strategy. Heterogeneity was assessed by using the Cochran Q test and I² statistics. The quality of evidence was evaluated using the GRADE approach.

RESULTS

A total of 5058 studies were identified, 66 of which met the eligibility criteria and of these 5 were judged "low" risk of bias and 57 were meta-analyzed. We did not observe significant differences in the NMA analysis for any two pairs of adhesives, except for the shortest follow-up for 2ER vs 3ER. The material 2SE ranked highest, although it differed only slightly from the other bonding strategies.

CONCLUSIONS

No bonding strategy is better than the others.

CLINICAL RELEVANCE

Adhesive efficacy cannot be characterized by its bonding strategy.

Secondary caries risk of different adhesive strategies and restorative materials in permanent teeth: Systematic review and network meta-analysis

OBJECTIVES

Secondary caries is a major long-term complication of dental restorations. Different adhesive strategies and restorative materials may affect secondary caries risk. We aimed to systematically review and synthesize the secondary caries risk of different adhesive strategies and restorative materials.

SOURCES

Medline via PubMed 01/2005-10/2019.

STUDY SELECTION

Randomized controlled studies with minimum 2 years follow-up, comparing different adhesive strategies and/or restorative materials in permanent teeth were included. Our outcome was the occurrence of secondary caries. Bayesian pairwise and network-meta-analysis were conducted.

DATA

We included 50 trials; 19 assessing secondary caries depending on different adhesive strategies, 31 on restorative materials. Studies were published between 2005 and 2017, largely of unclear risk of bias, and included a mean of 40 (range: 8-90) participants and 46 (range: 14-200) placed restorations. Mean follow-up was 43 (range: 24-180) months. Secondary caries was a rare event; the majority of studies did not find any lesions. Network meta-analysis found great uncertainty. 3-step etch-and-rinse adhesives showed the lowest risk of secondary caries, 2-step etch-and-rinse the highest. For restorative materials, resin-modified glass ionomer showed the lowest risk of secondary caries. Most resin composites showed similar risks.

CONCLUSION

Data from randomized trials comparing different adhesive strategies or restorative materials are extremely scarce. The differences between materials were limited over the observational period of the included studies. The yielded rankings should be interpreted with caution.

CLINICAL SIGNIFICANCE

Despite often claimed to be a major complication of restorations, there is surprisingly little data on secondary caries from randomized trials. Longer-term studies may be needed to identify differences in secondary caries risk between materials.

Outcome and comparator choice in molar incisor hypomineralisation (MIH) intervention studies: a systematic review and social network analysis

OBJECTIVES

Outcome and comparator choice strongly determine the validity and implementation of clinical trial results. We aimed to assess outcome and comparator choice in intervention studies on molar incisor hypomineralisation (MIH) using systematic review and social network analysis (SNA).

DESIGN AND DATA SOURCES

Medline, Embase, Cochrane Central, Google Scholar, opengrey.eu as well as DRKS.de and Clinicaltrials.gov were searched for MIH intervention studies. The search covered the period from 1980 to 2019.

ELIGIBILITY CRITERIA

Clinical single-arm/multiarm, controlled/uncontrolled studies reporting on the management of MIH were included. Reported outcomes and comparators were extracted and categorised. SNA was used to evaluate comparator choice and the resulting trial networks.

DATA EXTRACTION

Of the 7979 identified records, 100 were evaluated in full text and 35 studies (17 randomised controlled trials, 14 prospective and 4 retrospective cohort studies) were included.

RESULTS

In total, 2124 patients with a mean age of 11 years (min/max 6/70 years) were included. Outcomes fell in one of 11 different outcome categories: restoration success, aesthetic improvement, pain/hypersensitivity/discomfort, mineral gain, space management, anaesthesia effectiveness, preventive success, efficiency, quality of life, gingival and periodontal health and patient satisfaction. Comparators were mainly restorative interventions (17 studies), remineralisation (3), treatment of hypersensitivity (10), aesthetic interventions (5) and orthodontic interventions (3). Two highly clustered comparator networks emerged; many interventions were not robustly linked to these networks.

CONCLUSIONS

MIH intervention studies recorded both clinically centred and patient-centred outcomes. Core outcome set development should consider these and supplement them with outcomes on, for example, applicability. The high number of compared interventions tested in only few studies and our SNA results implicate that the current evidence may not be robust.

Comparator Choice in Studies Testing Endodontic Instrument Fatigue Resistance: A Network Analysis

AIMS

Endodontic instruments are frequently compared against each other for their cyclic fatigue resistance (CFR). It is unclear what drives the comparator choice in CFR studies, and how comparators and comparisons have evolved over time. We aimed at evaluating CFR study networks, hypothesizing that indications and instrument properties (alloy, manufacturer) drive comparisons.

METHODS

A systematic review was performed via Medline and Embase (1986-2017). In vitro studies analyzing the CFR of ≥2 engine-driven instruments in an artificial curved root canal system were included. We classified instruments according to name, alloy, and manufacturer. Study networks were analyzed using social network analysis techniques.

RESULTS

Eighty-five studies on 56 different instruments (9 alloys, 17 manufacturers) were included. For instruments, a low-density (0.19), highly clustered (0.71) network with 3 separate subnetworks (for glide path, shaping, and retreatment instruments) emerged. Certain instruments (ProTaper Universal [Dentsply Maillefer, Ballaigues, Switzerland], Mtwo [VDW Dental, Munich, Germany]) served as hub nodes and possible gold standards. Conventional Nickel-Titanium was the most frequently used alloy. Few manufacturers dominated the network. The diversity of tested instruments, alloys, and manufacturers increased in recent years.

CONCLUSIONS

Comparisons of CFR were usually made along indications. Some instruments and alloys (conventional Nickel-Titanium) dominated the networks. Overall risk of bias by comparator choice seems moderate; however, the evidence on certain, less often tested instruments may not be robust. Factors underlying the network geometry (eg, sponsorship) should be explored.

Does Classification of Composites for Network Meta-analyses Lead to Erroneous Conclusions?

Objectives: 

Composites can be classified differently, according to manufacturer information, filler particle size, resin-monomer base, or viscosity, for example. Using clinical trial data, network meta-analyses aim to rank different composite material classes. Dentists then use these ranks to decide whether to use specific materials. Alternatively, annual failure rates (AFRs) of materials can be assessed, not requiring any classification for synthesis. It is unclear whether different classification systems lead to different rankings of the same material (ie, erroneous conclusions). We aimed to evaluate the agreement of material rankings between different classification systems.

Methods: 

A systematic review was performed via MEDLINE, Cochrane Central Register of Controlled Trials, and EMBASE. Randomized controlled trials published from 2005-2015 that investigated composite restorations placed in load-bearing cavitated lesions in permanent teeth were included. Network meta-analyses were performed to rank combinations of composite classes (according to manufacturer, filler particle size, resin-monomers, viscosity) and adhesives. Material combinations were additionally ranked using AFRs.

Results: 

A total of 42 studies (6088 restorations, 2325 patients) were included. The ranking of most material class combinations showed significant agreement between classifications (R2 ranged between 0.03 and 0.56). Comparing material combinations using AFRs had low precision and agreement with other systems. AFRs were significantly correlated with follow-up periods of trials.

Conclusion: 

There was high agreement between rankings of identical materials in different classification systems. Such rankings thus allow cautious deductions as to the performance of a specific material. Syntheses based on AFRs might lead to erroneous results because AFRs are determined by follow-up periods and have low precision.

Clinical studies in restorative dentistry: Design, conduct, analysis

OBJECTIVE

Clinical studies should be one main aspect underlying dentists' decision-making towards dental materials. Study design, conduct, analysis and reporting impact on the usefulness of studies. We discuss problems with current studies and highlight areas where improvement might be possible.

METHODS

Based on systematically and non-systematically collected data, we demonstrate where and why current studies in clinical dentistry deliver less-than-optimal results. Lending from general medicine, we suggest ways forward for clinical dental material science.

RESULTS

Randomized controlled (efficacy) trials remain a major pillar in dental material science, as they reduce selection bias and, if well-designed and conducted, have high internal validity. Given their costs and limited external validity, alternatives like practice-based or pragmatic controlled trials or observational studies can complement the evidence-base. Prior to conduct, researchers should focus on study comparators and setting (answering questions with relevance to clinical dentistry), and pay attention to statistical power, considering the study aim (superiority or non-inferiority trial), the expected event rate, and attrition. Study outcomes should be chosen on the basis of a core outcome set or, if not available, involving patients and other stakeholders. Studies should be registered a priori, and reporting should adhere to standards. Possible clustering should be accounted for during statistical analysis.

SIGNIFICANCE

Many clinical studies in dental material science are underpowered, and of limited validity and usefulness for daily decision-making. Dental researchers should mirror existing efforts in other medical fields in making clinical studies more valid and applicable, thus contributing to better dental care.

Directly Placed Restorative Materials

For restoring cavitated dental lesions, whether carious or not, a large number of material combinations are available. We aimed to systematically review and synthesize data of comparative dental restorative trials. A systematic review was performed. Randomized controlled trials published between 2005 and 2015 were included that compared the survival of ≥2 restorative and/or adhesive materials (i.e., no need for restorative reintervention). Pairwise and Bayesian network meta-analyses were performed, with separate evaluations for cervical cavitated lesions and load-bearing posterior cavitated lesions in permanent and primary teeth. A total of 11,070 restorations (5,330 cervical, 5,740 load bearing) had been placed in 3,633 patients in the included trials. Thirty-six trials investigated restoration of cervical lesions (all in permanent teeth) and 36 of load-bearing lesions (8 in primary and 28 in permanent teeth). Resin-modified glass ionomer cements had the highest chance of survival in cervical cavitated lesions; composites or compomers placed via 2-step self-etch and 3-step etch-and-rinse adhesives were ranked next. Restorations placed with 2-step etch-and-rinse or 1-step self-etch adhesives performed worst. For load-bearing restorations, conventional composites had the highest probability of survival, while siloranes were found least suitable. Ambiguity remains regarding which adhesive strategy to use in load-bearing cavitated lesions. Most studies showed high risk of bias, and several comparisons were prone for publication bias. If prioritized for survival, resin-modified glass ionomer cements might be recommended to restore cervical lesions. For load-bearing ones, conventional or bulk fill composites seem most suitable. The available evidence is quantitatively and qualitatively insufficient for further recommendations, especially with regard to adhesive strategies in posterior load-bearing situations. Moreover, different material classifications might yield different findings on the same materials. Future trials should aim for sufficient power, longer follow-up times, and high internal validity to prove or refute differences between certain material combinations. An agreed material classification for future syntheses is desirable.