The evaluation of the effects of saliva contamination on microhardness and fracture strength of different aged restorative materials

Background: This research aimed to investigate the effects of saliva contamination on the microhardness and fracture strength of different types of aged restorative materials under in vitro conditions. Methods: 90 samples assigned to compomer, glass hybrid restorative (GHR), and conventional glass ionomer restoratives (CGIR) were prepared using round-shaped molds (diameter: 6 mm, depth: 2 mm). Samples in main groups were subdivided to simulate a saliva-contaminated (n = 15) and non-contaminated conditions/cases (n = 15). In saliva-contaminated subgroups, artificial saliva solution was applied to all surfaces of the molds, and restorative materials were placed. All samples were thermocycled with a temperature of 5–55 ◦C, 30 seconds dwell time and 5000 cycles for aging. The surface hardness and then fracture strength were measured and recorded. Statistical tests were performed with Kruskal-Wallis-H and Mann-Whitney U tests. The significance level was set at 0.05. Results: In both saliva-contaminated and non-saliva-contaminated samples, glass hybrid restorative showed the highest microhardness, while compomer provided the best fracture strength (p < 0.05). For compomer material, no significant difference was found in terms of hardness and fracture strength between saliva-contaminated and non-contaminated samples (p > 0.05). For glass hybrid restorative material, non-saliva contaminated samples showed significantly higher fracture strength (p < 0.05). In conventional glass ionomer material, non-saliva contaminated samples showed significantly higher microhardness values (p < 0.05). Conclusions: Within the limitations of this study, it is recommended that saliva contamination be prevented as much as possible in order not to adversely affect the fracture strength in glass hybrid restorations and microhardness values in conventional glass ionomer restorations.

Compomer; Conventional glass ionomer; Fracture strength; Glass hybrid restorative; Microhardness; Saliva contamination

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