Abstract:

Objective To evaluate the sensitivity of swept-source optical coherence tomography(SS-OCT) in detecting early demineralization at the resin-enamel bonding interface, and the differences in enamel demineralization around restorations among different resins(Filtek Z350 XT, Filtek Bulk Fill, TetricN-Ceram Bulk Fill). Methods Twenty-seven extracted third molars were selected and prepared into 5-mm-thick specimens, and Class Ⅰ cavities measuring 3 mm × 3 mm × 4 mm were created on the occlusal surfaces. The specimens were randomly divided into three groups, with nine teeth in each group, and were respectively filled with Filtek Z350 XT(layered filling of 4 mm), Filtek Bulk Fill(bulk filling of 4 mm in one step), and Tetric N-Ceram Bulk Fill(bulk filling of 4 mm in one step). After applying acid-resistant nail varnish to non-experimental areas, the specimens were placed in a demineralizing solution for 4 weeks. SS-OCT and Micro-CT scans of the resin-enamel bonding interface were performed before demineralization and weekly thereafter to monitor the progression of demineralization and changes in demineralization depth were quantitatively analyzed. Results Both SS-OCT and Micro-CT were capable of non-destructive dynamic monitoring of demineralization at the resin-enamel bonding interface. After demineralization, four types of patterns were observed at the resin-enamel bonding interface. At different stages of demineralization, no significant differences in demineralization depth were detected among the three resins using either SS-OCT or Micro-CT. There was a high level of agreement between the demineralization depth measurements obtained from SS-OCT and Micro-CT at each demineralization stage(ICC: 0.760-0.897). Conclusion The early demineralization of resin-enamelbonding interface can be noninvasively detected by SS-OCT, and there was no significant differenceamong three resins in their ability to resist enamel demineralization around the restoration.

Key words: optical coherence tomography, bulk fill resin, resin-enamel interface demineralization