Bacterial biofilm accumulation is problematic in many areas, leading to biofouling in the marine environment and the food industry, and infections in healthcare. Physical disruption of biofilms has become an important area of research. In dentistry, biofilm removal is essential to maintain health. The aim of this study is to observe biofilm disruption due to cavitation generated by a dental ultrasonic scaler (P5XS, Acteon) using a high speed camera and determine how this is achieved. Streptococcus sanguinis biofilm was grown on Thermanox™ coverslips (Nunc, USA) for 4 days. After fixing and staining with crystal violet, biofilm removal was imaged using a high speed camera (AX200, Photron). An ultrasonic scaler tip (tip 10P) was held 2 mm away from the biofilm and operated for 2 s. Bubble oscillations were observed from high speed image sequences and image analysis was used to track bubble motion and calculate changes in bubble radius and velocity on the surface. The results demonstrate that most of the biofilm disruption occurs through cavitation bubbles contacting the surface within 2 s, whether individually or in cavitation clouds. Cleaning occurs through shape oscillating microbubbles on the surface as well as through fluid flow.

中文翻译：

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超声空化如何去除牙齿细菌生物膜？

细菌生物膜的积聚在许多领域都存在问题，导致海洋环境和食品工业中的生物污染以及医疗保健中的感染。生物膜的物理破坏已成为重要的研究领域。在牙科领域，去除生物膜对于维持健康至关重要。这项研究的目的是观察使用高速摄像头的牙科超声洁牙机（P5XS，Acteon）产生的气蚀引起的生物膜破坏，并确定如何实现。血链球菌生物膜在Thermanox™盖玻片（美国Nunc）上生长4天。固定并用结晶紫染色后，使用高速相机（AX200，Photron）对生物膜去除进行成像。将超声洁牙机针头（针头10P）保持在距生物膜2 mm的位置，并操作2 s。从高速图像序列中观察到气泡振荡，并使用图像分析来跟踪气泡运动并计算表面上气泡半径和速度的变化。结果表明，大多数生物膜破坏是通过空化气泡在2 s内接触表面而发生的，无论是单独的还是在空化云中。清洁是通过表面上的形状振荡微气泡以及流体流动来进行的。