Ion Release and Flexural Strength of Bioactive Materials

Objectives: The term “bioactive” has become popular in dentistry, however, its definition in terms of dental materials is confusing. One criteria of a bioactive restorative material is its ability to release ions necessary to remineralize surrounding tooth structure. But limited data measuring calcium and fluoride release and strength of these materials has been reported. The aim of the present study is to measure the cumulative calcium and fluoride ion release at different pH of two potentially bioactive materials compared to a resin-modified glass ionomer (RMGI) and resin composite. Flexural strength after water storage was measured to see if ion release affects strength.
Methods: Two potentially bioactive materials (Activa; Pulpdent, Cention N; Ivoclar Vivadent), a RMGI (Fuji II LC, GC) and a resin composite (Filtek Supreme Ultra, 3M) were tested. Disc shaped specimens (15mmx1.5mm) were made and suspended in 50mL of deionized water(pH=7.0) (n=10) or acidic solution (pH 4.0) (n=8) to measure ion release. The fluoride and calcium ion release was measured using an ion specific electrode after 120 days. Flexural strength specimens (n=8) were made using a Teflon mold (2mmx2mmx20mm), light cured for 20s (3 cures each side) and stored in deionized water (1 or 120 days) at 37C. The specimens were subjected to a 3-point bend test at a crosshead speed of 1 mm/min. Results were analyzed with 1 or 2-way ANOVA (factors time and material for flexural strength) followed by Tukey HSD post-hoc tests (alpha=0.05).
Results: Means and standard deviations listed in table. Significant differences (p<.01) were seen between materials for release of both ions in both solutions. For flexural strength, the factors material and time and their interaction were significant (p<.01).
Conclusions: In solution, Cention N released significantly more calcium than all other materials. The RMGI F release was not significantly different Cention N has the ion release favoring possible remineralization.