Compare gap between dentin and composite using Optical Coherence Tomography and leakage test

Abstract

Background Composite resins have become the preferred option for dental restorations. Numerous studies have demonstrated that composite restorations can provide exceptional durability and longevity in clinical practice. However, gap formation at the resin-dentin interface can compromise the integrity of the restoration, potentially leading to its failure. There are many established methods to detect these gaps. Optical coherence tomography (OCT), Leakage tests, and many others may detect the gap successfully. Additionally, tooth structures can vary significantly based on their location. The study aimed to compare the gap formation between dentin and composite resin using OCT and the leakage test. Methods Three cavities were prepared for each bovine tooth (coronal, cervical, and root). Cavities were filled by Scotchbond Universal Plus Adhesive and Filtek Supreme Flowable Restorative. After the water storage (37°C, 24 h), the cavity bottom interface was observed using OCT. Continuously, these samples were cut for leakage test. Specimens were immersed in 50% ammoniacal silver nitrate solution (AgNO₃) and photo-development solution. Finally, Energy dispersive X-ray spectroscopy (EDS) analysis was performed on the cavity bottom interface. Two-dimensional (2D) images of both devices were analyzed to calculate a sealed interface percentage (SI%). Results At all sites (coronal, cervical, and root), EDS showed a significantly higher SI% value compared to OCT. No significant differences depending on sites were observed. Conclusion The influence of different cavity sites was not observed in both OCT and leakage tests. The differences in gap detection were observed between measurement devices, with EDS showing higher values than OCT at all sites.