BACKGROUND: The concept of constant and low levels of F intra-orally has been applied in dentistry using a controlled-release delivery system in different forms of slow-release F intra-oral devices. AIM: To investigate the effect of newly shaped plastic brackets on the level of fluoride released by the devices in vitro and to compare the level of fluoride released by unilateral versus bilateral slow-release fluoride glass devices in adults in vivo. STUDY DESIGN : The phase I, in vitro assessment involved 15 slow-release fluoride glass devices divided into three groups. Group A contained five glass beads, Group B, five fluoride devices placed with the plastic brackets facing down, and Group C, five fluoride devices placed with the plastic brackets facing up. Evaluation of fluoride release was carried out daily for a week, weekly for a month, and monthly for 18 months. The In vivo phase II involved 20 adults (mean age 29.7 ± 2.3 years) randomly divided and had unilateral or bilateral slow-release fluoride glass devices placed for six months. RESULTS : Groups A and B released fluoride for up to ten months. In Group C, the glass beads became loose at the end of the first month and were excluded from further analysis. There was no statistical significant difference in the mean of total fluoride released by Groups A and B. All participants showed higher salivary fluoride levels than at baseline. There was no statistically significant difference in the level of fluoride released by the bilateral and unilateral groups. CONCLUSIONS: The newly shaped slow-release fluoride glass devices showed continuous, safe, and effective fluoride release.