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 randomized controlled three year evaluation of "bulk-filled" posterior resin restorations based on stress decreasing resin technology.
OBJECTIVE The objective of this r and omized controlled prospect i ve clinical trial was to evaluate the efficacy of a flowable resin composite ( SDR ) bulk fill technique in posterior restorations and to compare it intraindividually with a conventional 2 mm resin composite curing technique in a 3-year follow up . MATERIAL S AND METHODS Thirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years ( range 32 - 87 ) . Each patient received at r and om at least two , as similar as possible , Class II or Class I restorations of two restorative techniques . In all cavities a single step self-etch adhesive ( Xeno V ) was applied . In one of the cavities of each pair , a flowable resin composite ( SDR ) was placed , in bulk increments up to 4 mm as needed to fill the cavity 2 mm short of the occlusal cavosurface . The occlusal part was completed with a nano-hybrid resin composite ( Ceram X mono ) layer . In the second cavity , the hybrid resin composite was placed in 2 mm increments . The restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 3 years . Caries risk and parafunctional habits of the participants were estimated . RESULTS After three years , 76 Class II and 28 Class I restorations could be observed . One molar resin composite-only tooth showed post-operative sensitivity during 3 weeks for temperature changes and occlusal forces . Two failed Class II molar restorations in the resin composite-only group were observed during the first year , one cusp fracture and one resin composite fracture . An annual failure rate of 1.3 % was found for the resin composite only restorations and of 0 % in the bulk-filled restorations ( n.s . ) . Ten participants were estimated as having high caries risk and eleven showed active bruxing habits . SIGNIFICANCE The 4 mm bulk-fill technique with the flowable resin composite SDR showed highly clinical effectiveness , which was comparable during the 3-year follow-up with the 2 mm resin composite layering technique
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 .