Direct and Transdentinal (Indirect) Antibacterial Activity of Commercially Available Dental Gel Formulations against Streptococcus mutans

Objective: To evaluate the direct and transdentinal (indirect) agar diffusion antibacterial activity of different commercially available antibacterial dental gel formulations against Streptococcus mutans. Materials and Methods: The commercially available dental gel formulations were Corsodyl® (COG, 1% chlorhexidine), Cervitec® (CEG, 0.2% chlorhexidine + 0.2% sodium fluoride), Forever Bright® (FOB, aloe vera), Gengigel® (GEG, 0.2% hyaluronic acid), 35% phosphoric acid gel and distilled water (control). Direct agar diffusion was performed by isolating three wells from brain-heart infusion agar plates using sterile glass pipettes attached to a vacuum pump and adding 0.1 ml of the gels to each well. Transdentinal (indirect) agar diffusion was performed by applying gel to 0.2- and 0.5-mm-thick human dentin discs previously etched with phosphoric acid and rinsed with distilled water. Zones formed around the wells and the dentin discs were measured and analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction (p 0.01). Results: Direct agar diffusion tests showed significant differences among all gel formulations (p 0.01) except for COG and CEG (p 0.01). COG and CEG exhibited higher antibacterial effects compared to FOB and GEG (p 0.01) in both direct and transdentinal (indirect) testing procedures. GEG did not show any antimicrobial activity in transdentinal (indirect) testing. Conclusion: Commercially available dental gels inhibited S. mutans, which may indicate their potential as cavity disinfectants.