Margin Integrity of Experimental and Commercial Ion-releasing Restorative Materials

To investigate marginal integrity of experimental and commercial ion-releasing restorative materials before and after thermomechanical loading (TML).

Standardized mesio-occlusal-distal (MOD) cavities (mesial margins 1 mm below the CEJ, distal margins 1 mm above the CEJ) were restored using six materials, following the manufacturer-recommended adhesive pretreatment, if applicable. One conventional, non-ion-releasing restorative material, Ceram.x Spectra ST (HV) (Dentsply Sirona, Charlotte, NC, USA), and five ion-releasing restorative materials were used (n=8 per group). Four of the ion-releasing materials were commercially available: Cention Forte (Ivoclar Vivadent, Schaan, Liechtenstein), Beautifil II LS (Shofu, Kyoto, Japan), ACTIVA BioACTIVE-RESTORATIVE (Pulpdent, Watertown, MA, USA), and Surefil one (Dentsply Sirona). In addition, an experimental resin composite restorative material with a fluoride-modified bioactive glass was specially produced for use in this study. TML was applied (1.2 M loading cycles, 1.7 Hz, 49 Newtons; 3000 thermal cycles, 5°C-50°C). Restoration margins were assessed before and after TML using scanning electron microscopy (200× magnification) and classified as continuous, noncontinuous, or nonjudgeable. Margin integrity was quantitatively expressed as the percentage of continuous margins in relation to the total measurable margin length. Data were analyzed using Wilcoxon signed-rank and Kruskal-Wallis tests, followed by Dunn post hoc tests and Bonferroni correction and Mann-Whitney U tests (α=0.05).

Each group exhibited significantly reduced marginal integrity after TML. The experimental resin composite showed the significantly highest continuous enamel margins before TML, whereas Surefil one had the lowest (p<0.001). Margin integrity in dentin did not differ significantly among groups (all p=0.236).

The experimental resin composite with a fluoride-modified bioactive glass exhibited marginal integrity similar or superior to a conventional resin composite, while the self-adhesive resin composite Surefil one displayed the lowest marginal adaptation of all groups in enamel.