pH and effects on S treptococcus mutans growth of denture adhesives: an in vitro study

Objectives To evaluate the pH and effects on S treptococcus mutans growth of denture adhesives. Background There is little information regarding the pH of contemporary adhesives and their influences on S . mutans growth. Materials and methods The adhesives tested were P olident ® cream, P rotefix ® cream and P rotefix ® powder. Samples of each adhesive were added to deionized water to produce solutions of 10.0, 5.0, 2.5 and 1.0% w/v (cream formulations) or 5.0, 2.5,1.0 and 0.5% (powder formulation). The pH values were measured immediately after preparation and at 1‐, 2‐, 3‐, 6‐, 12‐, and 24‐h intervals using a digital pH meter. Streptococcus mutans UA 159 was inoculated in the B rain H eart I nfusion medium with or without the adhesive extracts (control). Bacterial growth was observed by measuring absorption at 600 nm every 1 h for 12 h using a spectrophotometer. Results The tested adhesives generally remained relatively pH ‐stable over 24 h, ranging from 5.5 to 7.0. There were no statistically significant differences in S . mutans growth rates between the extract‐treated and control cultures ( p  > 0.5). Conclusions Some adhesives produce a pH below the critical pH of hydroxyapatite and may not be suitable for patients with natural teeth. None of the tested adhesives significantly affect S . mutans growth.