Micro-CT assessment of internal adaptation in Class V restorations using different liner/base strategies: a pilot study

The internal adaptation of pulp liner/base materials may influence interfacial gap formation and internal voids in restorations. This pilot in vitro study used high-resolution micro-computed tomography (Micro-CT) to evaluate interfacial gap volumes and internal void characteristics in Class V restorations using three liner/base strategies. In this in vitro pilot study, three liner/base strategies were evaluated: TheraCal LC, Ultra-Blend Plus, and a multilayer system consisting of Dycal combined with resin-modified glass ionomer cement (RMGI). Following standardized Class V cavity preparation, liner/base placement, composite resin restoration, and thermocycling, specimens were scanned using Micro-CT. The measured outcomes included interfacial gap volume at the tooth–liner and composite-liner interfaces, as well as internal void volume and porosity within the evaluated restorative systems. Data were analyzed using the Kruskal–Wallis test with exact permutation procedures at a significance level of α = 0.05. No statistically significant differences were observed among the three strategies at the composite-liner interface. At the tooth-liner interface, the median interfacial gap volume was significantly higher for TheraCal LC than for the Dycal + RMGI multilayer system. Although Ultra-Blend Plus showed an intermediate median value, its differences from the other groups were not statistically significant. The Dycal + RMGI system exhibited the highest internal void volume within the pulp-capping material. The three liner/base strategies showed different patterns of interfacial adaptation and internal void formation in this pilot study. The statistically significant difference in tooth-liner gap volume was limited to the comparison between TheraCal LC and Dycal + RMGI; no significant differences involving Ultra-Blend Plus were detected. Given the small sample size, these findings are preliminary and require confirmation in larger studies before their clinical relevance can be established.