Busscher H J, Jager D, Finger G, Schaefer N, van der Mei H C
Department of Biomedical Engineering, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
Eur J Oral Sci. 2010 Apr;118(2):177-82. doi: 10.1111/j.1600-0722.2010.00723.x.
Non-contact removal of oral biofilms offers advantages beyond the reach of bristles, but it is unknown how energy transfer for removal from brush-to-biofilm occurs. In the present study we evaluated non-contact, oral biofilm removal by oscillating-rotating and sonic toothbrushes, and their acoustic output up to 6 mm distance. Whereas some brushes removed biofilm when used at a distance of up to 6 mm, others lost efficacy at a distance of 2-4 mm from the biofilm. Loss of efficacy was accompanied with high standard deviations and volumetric biofilm expansion. Both sonic and oscillating-rotating brushes caused fluid flows and the inclusion of air-bubbles, while non-contact acoustic energy-transfer was demonstrated to decay with distance for both types of brushes. We put forward the following mechanism for non-contact removal: (i) brush energy is absorbed by biofilm, resulting in the visco-elastic expansion of the biofilm; (ii) if the energy absorbed is sufficient and deformation is beyond the yield point, biofilm removal occurs; and (iii) if deformation is in the plastic range but below the yield point (i.e. at the limiting distance for non-contact removal), biofilm is expanded but not removed.
非接触式清除口腔生物膜具有刷毛无法企及的优势，但尚不清楚从牙刷到生物膜的清除过程中能量是如何传递的。在本研究中，我们评估了振荡旋转牙刷和声波牙刷非接触式清除口腔生物膜的效果，以及它们在距离生物膜6毫米范围内的声学输出。虽然有些牙刷在距离生物膜最远6毫米处使用时能够清除生物膜，但其他牙刷在距离生物膜2 - 4毫米时就失去了效果。效果的丧失伴随着高标准差和生物膜体积膨胀。声波牙刷和振荡旋转牙刷都会引起流体流动并裹挟气泡，同时两种类型的牙刷非接触声能传递均随距离衰减。我们提出了以下非接触式清除机制：(i) 牙刷能量被生物膜吸收，导致生物膜粘弹性膨胀；(ii) 如果吸收的能量足够且变形超过屈服点，则会发生生物膜清除；(iii) 如果变形处于塑性范围内但低于屈服点（即非接触清除的极限距离），生物膜会膨胀但不会被清除。
