The meta- analysis of the data in the included studies demonstrated that only one variable ( marginal adaptation after 12 months ) showed statistically significant outcomes , in which methacrylates-based composites presented significantly better results than resin composites containing modified monomers .
The good level of the scientific evidence as well as the overall low risk of bias of the included studies indicate that composites with silorane , ormocer or bulk-fill type modified monomers have a clinical performance similar to conventional resin composites
Polymerization shrinkage of resin composite can compromise the longevity of restorations .
To minimize this problem , the monomeric composition of composites have been modified .
The objective of this study was to conduct a meta- analysis to assess the clinical behavior of restorations performed with low polymerization shrinkage resin composite  in comparison with traditional methacrylates-based resin composite .
Methodological quality of systematic reviews in subfertility: a comparison of Cochrane and non-Cochrane systematic reviews in assisted reproductive technologies.
STUDY QUESTION Are there differences in the method ological quality of Cochrane systematic review s ( CRs ) and non-Cochrane systematic review s ( NCRs ) of assisted reproductive technologies ? SUMMARY ANSWER CRs on assisted reproduction are of higher method ological quality than similar review s published in other journals . WHAT IS KNOWN ALREADY The quality of systematic review s varies . STUDY DESIGN , SIZE AND DURATION This was a cross-sectional study of 30 CR and 30 NCR systematic review s that were r and omly selected from the eligible review s identified from a literature search for the years 2007 - 2011 . MATERIAL S , SETTING AND METHODS We extracted data on the reporting and method ological characteristics of the included systematic review s. We assessed the method ological quality of the review s using the 11-domain Measurement Tool to Assess the Method ological Quality of Systematic Review s ( AMSTAR ) tool and subsequently compared CR and NCR systematic review s. MAIN RESULTS AND THE ROLE OF CHANCE The AMSTAR quality assessment found that CRs were superior to NCRs . For 10 of 11 AMSTAR domains , the requirements were met in > 50 % of CRs , but only 4 of 11 domains showed requirements being met in > 50 % of NCRs . The strengths of CRs are the a priori study design , comprehensive literature search , explicit lists of included and excluded studies and assessment s of internal validity . Significant failings in the CRs were found in duplicate study selection and data extraction ( 67 % meeting requirements ) , assessment for publication bias ( 53 % meeting requirements ) and reporting of conflicts of interest ( 47 % meeting requirements ) . NCRs were more likely to contain method ological weaknesses as the majority of the domains showed < 40 % of review s meeting requirements , e.g. a priori study design ( 17 % ) , duplicate study selection and data extraction ( 17 % ) , assessment of study quality ( 27 % ) , study quality in the formulation of conclusions ( 23 % ) and reporting of conflict of interests ( 10 % ) . LIMITATIONS , REASONS FOR CAUTION The AMSTAR assessment can only judge what is reported by authors . Although two of the five authors are involved in the production of CRs , the risk of bias was reduced by not involving these authors in the assessment of the systematic review quality . WIDER IMPLICATION S OF THE FINDINGS Not all systematic review s are equal . The reader needs to consider the quality of the systematic review when they consider the results and the conclusions of a systematic review . STUDY FUNDING /COMPETING INTEREST(S ) There are no conflicts with any commercial organization . Funding was provided for the students by the summer studentship programme of the Faculty of Medical and Health Sciences of the University of Auckl and
The meta- analysis of the data in the included studies demonstrated that only one variable ( marginal adaptation after 12 months ) showed statistically significant outcomes , in which methacrylates-based composites presented significantly better results than resin composites containing modified monomers .
The good level of the scientific evidence as well as the overall low risk of bias of the included studies indicate that composites with silorane , ormocer or bulk-fill type modified monomers have a clinical performance similar to conventional resin composites
Polymerization shrinkage of resin composite can compromise the longevity of restorations .
To minimize this problem , the monomeric composition of composites have been modified .
The objective of this study was to conduct a meta- analysis to assess the clinical behavior of restorations performed with low polymerization shrinkage resin composite  in comparison with traditional methacrylates-based resin composite .