Non-destructive evaluation of an internal adaptation of resin composite restoration with swept-source optical coherence tomography and micro-CT.

•Micro-CT and SS-OCT may be useful non-destructive methods for evaluating internal adaptation.•The microleakge measured by micro-CT was lower than that of SS-OCT, however the two measurements were relatively high-correlated.•When adhesion depends mostly on the dentin surface, a two-step self-etch adhesive system should be considered for long-term longevity.