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 .
A double-blind randomized clinical trial of a silorane-based resin composite in class 2 restorations: 18-month follow-up.
PURPOSE To compare the clinical performance of a silorane-based with a methacrylate-based restorative system in class 2 restorations after an 18-month follow-up . METHODS This r and omized , double-blind and controlled study included 33 subjects receiving 100 direct resin composite restorations that were completely r and omized to silorane-based group ( Filtek P90/Silorane System Adhesive - 3 M ESPE ) or methacrylate-based group ( Filtek P60/Adper SE Plus - 3 M ESPE ) .  The restorative system was determined by chance using a coin toss until 50 units for each group were completed . Each subject contributed with one to seven restorations . A single operator performed all of the restorative procedures . Two calibrated examiners ( kw > or = 0.7 ) assessed the restorations at baseline and after 18 months according to modified United States Public Health System ( USPHS ) criteria . The data were analyzed with Mann-Whitney U-test , Wilcoxon signed rank and Kaplan-Meier survival curves ( alpha = 0.05 ) . RESULTS After 18 months , 88 restorations were evaluated , and five unacceptable restorations were observed . Proximal contact loss was the main reason for failure ( three ) followed by composite fracture ( two ) . The marginal integrity of the silorane-based group was significantly worse than that of the methacrylate-based group ( P= 0.035 ) . Comparing baseline to 18-month evaluations , the silorane-based group showed significant differences for marginal discoloration , marginal integrity and surface texture ( P < 0.05 ) ; and the methacrylate-based group differed significantly for marginal discoloration and surface texture ( P < 0.05 ) . Combined survival rate for both groups together was 95 % . No statistically significant difference was found between methacrylate-based ( 98 % ) and silorane-based ( 92 % ) overall survival rate ( Log rank test ; P = 0.185 )
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 .