Comparative of flexural strength, hardness, and fluoride release of two bioactive restorative materials with RMGI and composite resin

Abstract

Aim: This study was fulfilled to evaluate the flexural strength, micro-hardness, and release of two fluoride ions of bioactive restorative materials (Cention N and Activa Bioactive), a resin modified glass ionomer (Fuji II LC), and a resin composite (Filtek z250). Methods: Forty samples from four restorative materials (Activa Bioactive, Fuji II LC, Cention N, and Filtek Z250) were provided according to the current standards of ISO 4049/2000 guide lines. Subsequently, the samples were stored for 24 hours and 6 months in artificial saliva, and successively, flexural strength and micro-hardness of the samples were measured. For each studied groups the pH was decreased from 6.8 to 4 in storage solution. The rate of changes in fluoride ion release was measured after three different storage periods of 24 hours, 48 hours, and 6 months in distilled water, according to the previous studies’ method. Two-way ANOVA, One-way ANOVA, Tukey HSD Pair wise comparisons, and independent t-tests were used to analyze data (α= 0.05). Results: The highest flexural strength and surface micro-hardness after 24 hours and also after 6 month were observed for Cention N(p<0.001).Flexural strength of all samples stored for 6 months was significantly lower than the samples stored for 24 hours(p<0.001). The accumulative amount of the released fluoride ion in RMGI, after six-month storage period in distilled water was considerably higher (p<0.001) than 24 hours and 48 hours storage. The amount of fluoride ion release with increasing acidity of the environment (from pH 6.8 to 4) in Fuji II LC glass ionomer was higher than the bioactive materials (p<0.05). Conclusion: The flexural strength of RMGI was increased after storage against the Activa Bioactive,Cention N and Z250 composite. Storage of restorative materials in artificial saliva leads to a significant reduction in micro hardness. The behavior and amount of released fluoride ions in these restorative materials, which are stored in an acidic environment, were dependent on the type of restorative material.

The Release of Fluoride Ions of Bioactive Resin in the Solution of Lactic Acid and Artificial Saliva

“…Fluoride ion dynamics provide an advantage for tooth that have a high susceptibility to caries. 7 In the oral cavity, many factors may affect the amount of fluoride ion release in bioactive composite resins, one of which is the pH value of oral cavity and also saliva. In the present study, to represent the condition of oral cavity we conducted for the treatment of bioactive resin in the immersion of lactic acid and artificial saliva.…”

“…The loss of material may attributed to the higher amount of resin matrix leads to increase water absorption and softening the specimen ion release from filler particles can result in separating of the matrix and filler, and also by micro-cracks forming in the interface of filler-matrix interface pH. 7,18 Based on the results of study that has been carried out, the least amount of fluoride ion release was found in the bioactive composite resin immersed in artificial saliva for one day, although the pH value of artificial saliva was lower than that of distilled water. This possibility may occur due to the difference in viscosity between artificial saliva and distilled water.…”

“…14 The release of fluoride ions can also occur when bioactive composite resins are exposed to saliva and solutions with critical pH. 7 The use of immersion media also has an effect on the amount of fluoride ion released. The study conducted by Eriwati (2020) showed that the immersion of bioactive resins in a solution of critical pH (4.5) and normal pH (7.0) released more fluoride ions in critical pH.…”

“…6 As the times progress, the use of resin based restorative materials is significantly increased. 7,8 Composite resins are globally used due to good aesthetics with high strength. In 2013 bioactive composite resin was introduced as a bioactive restorative material with the "smart behaviour".…”

“…In 2013 bioactive composite resin was introduced as a bioactive restorative material with the "smart behaviour". 7,9 The bioactivity of these materials can be attributed to its ability to release ions and provide ionic exchange with saliva and tooth structure thereby remineralization could be promoted surrounding tooth structure. Bioactive composite resins consist of matrix and filler from that differed from conventional composite resins.…”