Comparative Evaluation of Microhardness of Hydrophilic Sealant and Flowable Composite on Permanent Molars- in vitro Study

Objectives: Dental caries, or tooth decay, is one of the most prevalent chronic diseases globally. Despite advancements in oral hygiene practices and widespread fluoride use, these measures have proven less effective against occlusal caries compared to smooth-surface caries. Hydrophilic sealants and flowable composites are commonly employed as sealing materials to address this issue. This in-vitro study evaluates the comparative microhardness of hydrophilic sealants and flowable composites, with a focus on their potential clinical applications. Methods: Ten extracted molar samples were divided into two groups: Group I (Ultra-seal XT Hydro sealant) and Group II (Ivoclar Tetric n Flow composite). Each group was further subdivided into immediate and ageing subgroups. Mesiodistal sectioning of the teeth was performed and each tooth was sectioned into two halves using a low-speed diamond cutting blade. One-half was subjected to immediate microhardness testing, while the other underwent thermocycling to simulate ageing. A slot was created on the buccal surface, which was then etched, sealed and light-cured. Microhardness was measured using a Vickers hardness tester under a 200 g force for 20 seconds. Thermocycling involved immersion in a water bath at temperatures ranging from 5°C to 55°C for 15 seconds at each degree, followed by a 10-second dwell time, over 1500 cycles. Statistical analysis included the Mann-Whitney U test to compare groups and the Wilcoxon test to assess differences within groups. Results: The immediate mean microhardness for Group I (26±3.70) was higher than Group II (21.38±6.15), but the difference was statistically insignificant. Similarly, ageing microhardness values for Group I (27.62±5.61) were higher than Group II (24.12±6.92), with no statistically significant difference. Within-group analysis using the Wilcoxon test revealed no significant differences between immediate and ageing subgroups. Conclusion: While no statistically significant differences were observed, hydrophilic sealants demonstrated slightly higher microhardness values than flowable composites. These findings underscore the potential of hydrophilic sealants in clinical applications, though further in-vivo studies are needed to validate their long-term performance and practical relevance.