Table 1: Studies that investigated micro leakage and marginal adaptation of flowable composites.

First author + year	Site of resin application	Tested variables	Conclusion
Olmez, A [22] 2004	Class II composite restorations with the margins below the cemento-enamel junction as a liner	Marginal microleakage and internal voids	The use of flowable resin composites provided a reduction in marginal microleakage and a reduction in some parts of the internal voids or total voids
Tredwin, C.J [23] 2004	Class II cavities as aliner	Micro leakage	Leakage data do not support the use of flowable resin composite linings in Class II resin composite restorations
Lindberg, A [24] 2005	Class II resin composite restorations as a liner	Interfacial adaptation	Neither the use of flowable resin composite liner nor the curing used influenced the interfacial adaptation
Loguercio, A. D [25] 2005	Class V as a liner	Clinical performance over 1 year	The use of Filtek Flow as a liner under Filtek Z250 restorations did not improve the clinical performance of class V restorations after 6 and 12 months of evaluation.
Efes, B.G [26] 2006	Occlusal cavity as a liner	Two –year clinical performance	The clinical performance of occlusal restorations did not benefit from the additional use of the flowable composite.
Celik, C [27] 2007	Non-carious cervical lesions.	Two-year clinical performance	Different types of resin materials demonstrated acceptable clinical performance in non-carious cervical lesions.
Sadeghi, M [28] 2009	Class II as gingival liner	Micro leakage	The groups utilizing flowable liners had significantly less microleakage with no significant difference between utilizing flowable composite or flowable compomer
Kubo, S [29] 2010	Non-carious cervical lesions	Three-year clinical performance	There were no significant differences in the clinical performances between the hybrid and the flowable composite for each variable acceptable clinical performance up to 3 years.
Gallo, J.R [30] 2010	Occlusal as a restoration	Clinical efficacy	Marginal discoloration and marginal adaptation significantly worsened at 36 months.
Van dijken, J.W [31] 2011	Class II restorations as a liner	Long term clinical performance	The use of flowable resin composite as an intermediate layer did not result in improved effectiveness of the Class II restorations
Simi, B [32] 2011	Class II as a liner	Micro leakage	Both resin-modified and flowable composite liners under nanocomposite restorations result in comparable reduction of microleakage.
Bonilla, E.D [33] 2012.	Minimally invasive occlusal restorations.	Micro leakage	Using flowable composite in minimally invasive occlusal restorations might result in undue restoration pitting or degradation.
Arslan, S [34] 2013	Class V restorations as intermediate material	Micro leakage	Micro leakage is not affected by the application of either conventional or new-generation flowable composite resin as an intermediate material between composite resin and dental substrates
Pecie, R [35] 2013	Class II as a liner	Marginal adaptation	The application of flowable composite as a liner may not improve marginal adaptation and is product dependent.