Microhardness of different esthetic restorative materials: Evaluation and comparison after exposure to acidic drink

Claudio Poggio, Matteo Viola, Maria Mirando, Marco Chiesa, Riccardo Beltrami, Marco Colombo


Background: Acidic beverages, such as soft drinks (orange juice and cola), can produce erosion
of resin composites. The aim of this in vitro study was to evaluate the effect of immersion in acidic
drink on the Vickers microhardness (VK) of different esthetic restorative materials (one nanohybrid
Ormocer‑based composite, one nanoceramic composite, one nanofilled composite, and one
microfilled hybrid composite).
Materials and Methods: In this in vitro study, thirty specimens of each esthetic restorative
material were divided into three subgroups (n = 10): specimens of group 1 were used as control,
specimens of group 2 were immersed in 50 ml of acidic drink for 1 day, specimens of group 3 were
immersed in 50 ml of acidic drink for 7 days. Data were analyzed by Shapiro–Wilk test to assess
the normality of the distributions followed by nonparametric Kruskal–Wallis analysis of variance
and Mann–Whitney U‑test comparison test among groups. A significant level of α = 0.05 was set
for comparison between the groups.
Results: Mann–Whitney U‑test showed that each material showed lower microhardness values
after immersion in acidic solution (P < 0.05). Paired t‑test confirmed that microhardness for each
composite did not change after immersion in distilled water (Control group) (P > 0.05). Significant
changes were registered for all restorative materials after immersion in acidic solution for 1 day
and 7 days (P < 0.05).
Conclusion: The Filtek Supreme XTE, a nanofilled composite, and Admira Fusion, a nanohybrid
ormocer‑based composite, showed the best behavior. The Ceram X Universal (nanoceramic
composite) although reached lower hardness values than the previous materials, but resisted well to
the 1 week immersion in soft‑drink. Finally, the Gradia Direct achieved the most disappointing results:
Low microhardness values are justified by the nature of its filling (microfilled hybrid composite).
Key Words: Acidic, drink, erosion, hardness, restorative materials

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