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Clinical studies

Superiority of PERIOBRUSH/BROXODENT®/BROXO® OraBrush® again highlighted by sophisticated studies, the results of which have just been published (trefny, cobb)

Several scientific research have been conducted in recent years in order to establish precisely what the brushing parameters of an electric toothbrush should be in order to obtain maximum efficiency. These various studies have enabled the following parameters to be set:

The maximum speed of the bristle tips must be at least 1.5m/s. This speed depends on the frequency of the oscillation or rotation of the brush stem which must have specific minimum values and on the amplitude of the motion of the brush stem bristle tips.

Since in most cases the brush’s bristles, even if they have small diameter, cannot penetrate into the interdental spaces or the sub-gingival pockets, it is essential, using the “coupling” liquid available, namely toothpaste, saliva and, if applicable, water, to produce beyond the bristles tip an acoustic pressure and a shear stress, alternative capable of removing a significant amount of bacterial plaque at a distance of a least 2mm.

Studies have shown that at 2mm from the bristle tips, the acoustic pressure should have a value of over 1.5 KPa and the shearing strain should be over 50 Pa. 3 scientific studies were carried out in late 1995 and the first half of 1996 to measure the performance of the PerioBrush/Broxodent®.

The first study, conducted in December 1995 by Pr.Trefny, Head of the Department of Physics of the Colorado School of Mines, enabled the following parameters to be measured and calculated. (for the details, see accompanying table).

Max. velocity at the tips of bristles of the PerioBrush/Broxodent® over 2.3 m/s (excellent).

For comparison purposes, Braun only reaches 0.89 m/s.

Acoustic pressure with a perpendicular sensor placed 2mm away from the bristle tips of the PerioBrush/wbroxodent (see fig.1 and 2 attached) between 0.7 and 1.6 KPa.

Acoustic pressure with sensor at 45° placed 2mm away from the bristle tips of the PerioBrush/Broxodent (see fig. 3 and 4) between 1.5 and 3 KPa.

Shear stress produced by the PerioBrush/Broxodent® and calculated on the basis of velocity: 120 to 130 Pa.

For comparison purposes, Braun only reaches 31.2 Pa.

The second study, this time in vivo, conducted in February 1996 by Cobbs (DDS,MS,PhD), Professor of Periodontics and Oral Biology at the Dental school of the University of Kansas-Missouri, found that with the bristles tip situated 2mm away from the surface of the tooth treated (with a coupling liquid), plaque was effectively removed from the surface of the enamel, without any contact between the bristles and the tooth.

However, Dr Cobb concluded that the test conditions did not correspond to practical or additional conditions and that in real life, the result would certainly be very different due to the lack of coupling liquid (saliva toothpaste).

To measure the acoustic pressure and shear stress parameters under conditions very similar to those in practice, Dr Trefny, assisted by Dr Munoz carried out a new series of tests described in the report dated from 10 March 1996.

The measuring probe was concealed beneath the interdental spaces at 2mm (see Exhibit A and D). Under these conditions, and holding the electric brush in the hand and with the bristles disposed at approximately 45° in relation to the gum, and with the froth created by toothpaste (without water) as the sole coupling means, acoustic pressure values are obtained equal to 4.0 Kpa (see also appendix 4), similar to those obtained with a “good” water coupling.

As regards shear stress, a measuring device was built to enable this stress to be measured properly (see exhibit O, P, Q) and not calculated using a formula which is debatable on account of the system’s kinematic complexity (bristles in motion, skew surface, etc.).

Furthermore, after taking reference measurements using water as a coupling means, the measurements were taken with the tooth paste froth as a coupling.

Finally, a series of measurements was taken adding bacteria to the measurement range in order to simulate dental plaque.

The results are very interesting (see also appendix II).

  • With water and without bacteria, the shear stress reaches 210 Pa.
  • With water and bacteria, this stress increases to 270 Pa due to the roughness of the surface caused by bacteria.
  • With toothpaste froth (without bacteria), this shear stress falls to 110 Pa Due to the coupling being less good.
  • With toothpaste and bacteria, this stress rises again to 230 Pa.



These in-depth studies and measurements have made it possible for the first time as regards shear, to accurately quantify the various parameters, under conditions which are very close to those of practical use.

It has also been possible to measure and prove, by means of Dr Cobb’s in vivo study, that the PerioBrush/Broxodent® removed dental plaque effectively at the distance of 2mm from the bristle tips (without any contact between the bristles and the tooth), which means that inaccessible places such as the transmission of the undulatory energy of the motion of the device’s bristle tips via a coupling liquid such as toothpaste or saliva.

As the results of the 2nd study conducted by Dr Trefny showed unquestionably that under conditions very close to those of practical use, remote transmission of energy was obtained by virtue of toothpaste froth as a coupling means, it may be asserted that an electric toothbrush has a major advantage over manual brushes, which, for their part, do not allow any remote transmission of energy (no rapid alternating sinusoidal motion), hence the need to use toothpicks, dental floss etc. with manual toothbrushes.

Finally, if we compare the recommended values for the 3 parameters - bristle tip velocity, acoustic pressure and shear stress - with those obtained with the PerioBrush/Broxodent, we find that the latter are far higher than the recommended values. This explains why PerioBrush/Broxodent has always come out top in the many in vivo clinical studies conducted since the 1960s.

Previously to this study, other clinical studies have been published as the one of, Dr J. Slots, University of Southern California of Dentistry, who confirms the above mentioned results. If we compare the results of Slots and Cobb we clearly see that the Sonic effects of BROXODENT ['klassic]® and BROXO® [per'io.brush/son'ik] are superior even in their Sonic effects to the Sensonic of Waterpik/Teledyne.