Table 1.

Restorative materials used; description of groups and protocol according to manufactures' instructions.

Restorative Material	Adhesive System	Group	Protocol
Clearfil AP-X (Kuraray Medical Inc., Okayama, Japan) +	Clearfil SE Bond (Kuraray)	Microhybrid +SE	a) Primer for 20 s, dry with mild air flow, bond, air flow gently and light cure (LED) for 10 s. b) Composite in one increment within an acrylic matrix with the dentin, light cure for 30 s under a polyester matrix.
	Clearfil SE Protect (Kuraray)	Microhybrid +P
	Clearfil SE Protect – with 6 layers	Microhybrid +P+6	a + b + After the normal procedure of priming, bonding and composite placement*, 6 additional layers of primer and bond were applied over the composite surface.
Filtek Supreme (3M ESPE, St. Paul, MN, USA) +	Clearfil SE Bond	Nanohybrid +SE	a + b
Filtek Silorane (3M ESPE) +	Silorane System Adhesive (3M ESPE)	Silorane	Primer for 15 s with agitation of the brush, dry with mild air flow, light cure for 10 s, apply the bond, gently air flow and light cure for 10 s + b
Tytin amalgam (Kerr Corporation, Orange, CA, USA)	No bond	Amalgam	Condensed into an acrylic matrix with the dentin.

Note.

^*the composite built up was inserted leaving approximately 0.3 mm space on top for the adhesive system layers.