Effect of bonding application time on the microleakage of Class V sandwich restorations

Background: The aim of this study was to assess the effect of bonding application time on the microleakage of Class V sandwich restorations. Methods: Eighty non‐carious third molars were randomly divided into 16 groups. Two Class V cavities were prepared on the buccal and lingual surfaces of teeth. Three groups were restored with Fuji II GIC and treated with a total‐etch bonding system (Stea/SDI) immediately after insertion, at 7 minutes and 15 minutes after mixing the glass ionomer cements (GICs). Another three groups were restored with Riva Self Cure GIC and treated with the total‐etch system identically. The other six groups were subjected to self‐etching bonding (Frog/SDI) after GIC placement in an identical procedure. The remaining groups were made using light cure GICs (Fuji II or Riva Light Cure) in conjunction with the total‐etch or self‐etching systems. Cavities were then restored with composite (Valux plus, 3M/ESPE). Samples were subsequently immersed in 2% methylene blue solution for 48 hours and observed under a stereomicroscope after sectioning. Four‐scale grading was used to assess microleakage in occlusal and gingival walls. Data were analysed using Kruskal–Wallis and Mann–Whitney tests. Results: The self‐etching bonding system exhibited more microleakage in occlusal margins regardless of time. Over time, microleakage significantly decreased in gingival margins in all self‐cure groups except for Riva Self Cure treated with the total‐etch system (p