Do bioactive restoratives prevent demineralization of adjacent proximal enamel? a laboratory study

Abstract

Aim: The aim of this laboratory study was to evaluate the preventive effect of various bioactive restorative materials on proximal enamel surfaces adjacent to approximal restorations under erosive conditions.

Materials and methods: Sixty sound human proximal enamel specimens were prepared and randomly assigned to four groups (n = 15). Each specimen was placed adjacent to an approximal restoration prepared using one of the following materials: Cention Forte (Ivoclar Vivadent AG, Liechtenstein), Equia Forte HT (GC Europe, Belgium), Beautifil II (Shofu, Japan), and Filtek Z550 (3 M ESPE, USA) as the control. All specimens were subjected to an erosive challenge by immersion in Coca-Cola for 15 min, three times daily for seven consecutive days. Surface roughness (Ra) and microhardness (VHN) values were measured at baseline and after the erosive challenge using a contact profilometer and a Vickers microhardness tester, respectively. Representative specimens (n = 3 per group) were imaged using scanning electron microscopy (SEM) to visualize surface changes, and were further analyzed by energy-dispersive X-ray spectroscopy (EDS) to determine elemental composition (F, Ca, P). Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (α = 0.05).

Results: Surface roughness increased significantly in all groups after the erosive challenge, with Cention Forte and Equia Forte HT exhibiting significantly lower roughness values than Filtek Z550 (p < 0.05). A significant reduction in microhardness was observed in all groups except for Equia Forte HT when compared to baseline (p < 0.05). Specimens adjacent to the resin composite showed a greater decrease in microhardness compared to those in contact with Equia Forte HT and Cention Forte (p < 0.05). EDS analysis revealed no statistically significant differences in elemental composition among the groups.

Conclusion: Compared to resin composite, bioactive materials such as Equia Forte HT and Cention Forte demonstrated greater potential in preserving the integrity of proximal enamel adjacent to approximal restorations under erosive conditions.

Keywords: Alkasite; Bioactive restorative materials; Enamel; Energy dispersive X-ray spectroscopy (EDS); Surface microhardness; Surface roughness.