AbstractThis study evaluated the influence of tubular density of different dentin depths and location on the bond strength of high-viscosity glass ionomer cements (GIC). A total of 20 molars were selected and assigned into six experimental groups, considering two different high-viscosity GICs—Fuji IX (FIX) or Ketac Molar (KM), and dentin location—proximal, occlusal superficial, or occlusal deep dentin (n=10). Teeth were cut and a topographical analysis of four sections per group was performed to obtain data about the tubular density of each different dentin location and depths by laser scanning confocal microscopy (100×). Polyethylene tubes were placed over the pretreated surfaces and filled with one of the GICs. Microshear bond strength (µSBS) test was performed after storage in distilled water (24 h at 37°C). Failure modes were evaluated using a stereomicroscope (400×). Multilevel regression analysis was performed to compare the results at a significance level set at 5%. The tubule density was inversely proportional to the bond strength for both GICs (p<0.05). Adhesive/mixed failure prevailed in all experimental groups. Proximal (30036.5±3433.3) and occlusal superficial 29665.3±1434.04 dentin shows lower tubule density, resulting in a better GIC bonding performance (proximal: FIX–3.61±1.05; KM–3.40±1.62; occlusal superficial: FIX–4.70±1.85; KM–4.97±1.25). Thus, we can concluded that the lowest tubule density in proximal and occlusal superficial dentin results in a better GIC bond strength performance.