background: This study aimed to evaluate the effect of bioactive composite (ACTIVA) on enamel demineralisation when used as an orthodontic adhesive, compared to other adhesives. Materials and methods: Human upper premolars (n=64) were randomly divided into two equal groups; the first group stored the bonded teeth in deionised water for 30 days at 37°C, and the second group exposed the bonded teeth to acidic media. Each group was further subdivided into four subgroups, with eight premolars in each subgroup, based on the type of adhesive used to bond metal brackets: non-fluoride-releasing adhesive (Transbond XT), fluoride-releasing adhesive (Light Bond), light-cured, resin-reinforced glass ionomer (GC Fuji ortho LC), and bioactive re