Fluoride release and anti-bacterial activity of different bioactive restorative materials: an in vitro comparative study

Introduction
Anti-bacterial properties of restorative materials through fluoride release enhance their inhibition ability against bacterial development, and reduce recurrent caries incidence.

Objectives
The aim of the current in-vitro research was to assess and compare fluoride release and anti-bacterial activity of three distinct bioactive dental restorations, such as resin-modified glass ionomer (RMGI), giomer, and Activa bioactive composite at different time intervals in vitro.

Material and methods
60 disc-shaped specimens were prepared and based on the kind of dental restoration materials, and were grouped into three equivalent major groups (20 specimens each group): RMGI (Fuji II LC), giomer (Beautifil II), and enhanced RMGI (Activa bioactive composite). Every main group was divided into two sub-groups based on the evaluator criteria, such as fluoride release (n = 15) and anti-bacterial action (n = 5). Based on storage duration, every fluoride release sub-group was then sub-divided into 3 equivalent divisions: 24 hours, 1 month, and 3 months (5 specimens each group). An ion-specific electrode was used to quantify fluoride. Anti-bacterial activity was recorded following one day according to sizes of inhibition zone.

Results
Fluoride release and anti-bacterial activity were statistically higher in Fuji II followed by Activa, while Beautifil II showed the least fluoride release. The fluoride release amount of all groups was greatest in the first 24 hours, and decreased significantly with time (1 month > 3 months).

Conclusions
Given the context of this research, RMGI presents better fluoride release and anti-bacterial activity than Activa and giomer.