The aim of this study was to elucidate whether marginal performance (in terms of % of continuous margins) can, or not, be predicted from microTBS values. A relationship was attempted between microTBS and % of continuous margins (% CM) before and after loading of class V restorations made with five restorative systems from both etch & rinse and self-etch approach.

Resin-dentin slabs and as well as class V cavities with cervical margins in dentin were prepared and restored using five adhesive systems (Scotchbond Multipurpose Plus (SMPP), James 2, Experimental Bond, Xeno III and iBond) with their corresponding restorative composites. Bond strength and percentages of continuous margins were calculated before and after thermal and mechanical loading. Statistical correlation was calculated between bond strength/marginal adaptation before loading and bond strength/marginal adaptation after loading of the same adhesives.

Ranking of materials according to their performance was test method dependent. A low weak correlation was found between bond strength and percentages of marginal adaptation.

No correlation could be established between strength of the bond and percentages of continuous margins. A direct comparison of bond strength with marginal adaptation data may be misleading.