Effect of Ultrasound Application on Biofilm Formation in Glass Ionomer Cements

Objectives: Objectives: To evaluate the influence of ultrasound application (UA) on biofilm formation (BF) and surface roughness (SR) in resin-modified (RMGI) and conventional (GIC) glass ionomer cements.
Methods: Methods: Standardized discs of each test restorative material, measuring 5mm (diameter) x 2mm (depth), were fabricated following the manufacturer’s instructions. Specimens were randomly assigned to one of seven groups (n=10): GIC Fuji IX GP (Group A); RMGI Fuji II LC (Group B); Ketac Nano (Group C); Fuji IX GP with UA (Group D); Fuji II LC with UA (Group E); and Ketac Nano with UA (Group F). Ultrasound was applied for 15s at 28kHz (Cavitron) with a dental scaler tip in contact with a Mylar strip that will cover the cements during the initial setting reaction. Specimens were stored in distilled water at room temperature for 48 h and then SR measurements were performed using a scanning white-light interferometer (SWLI). After SR measurements and overnight UV radiation sterilization, the samples were subjected to a biofilm model and then incubated for 24-hour cycles at 5% CO₂ at 37^o C before proceeding with both overall biofilm attachment. All measurements were performed by a single operator blinded to the procedures. SR results were analyzed employing non-parametric Mann-Whitney U test/Kruskal-Wallis test.
Results: Results: Ketac Nano with UA showed the lowest SR, and Fuji IX had the highest SR. UA decreased SR in all test materials. SR results are summarized in the table. The BF values (ΔOD570nm) for each group were: A = 2.2+0.4 (2.0+0.5), B = 3.2+0.4 (3.5+0.0), C = 2.2+0.2 (1.7+0.2), D = 1.7+0.4 (1.9+0.4), E = 2.8+0.5 (2.1+0.2), and F = 3.0+0.4 (2.2+0.7).
Conclusions: Conclusions: A reduction in SR of GI materials occurs when ultrasonic is applied during their initial setting reaction. BF was reduced with UA, except for Ketac Nano.