Toothbrushing Force has Significant Effect on Relative Dentine Abrasion(RDA)  Values

 Method: RDA was performed using the standard method as described by Hefferren (1976) modified by using two additional forces(50g and 250g) to the one normally used(150g). A calcium carbonate-based toothpaste(A) and a silica-based toothpaste(B) were used in combination with 3 commercially available medium hardness brushes(X, Y, Z) of very different bristle geometries, and abrasion performances of the combinations compared at the three forces 50g,150g,250g.

Result:

The ranking order of brushes was consistent between the two toothpastes and toothbrushes over the range of tensions used.  Trends within the results are the same for both chalk and silica toothpaste.  Toothbrush Y (angled and crossed multi-level bristle field) consistently gave the highest RDA value and the biggest change in RDA for a given increase in force. For brush Z RDA values plateau between 150g and 250g.

Brush   Force  Paste(A)RDA      Paste(B)RDA

x              50g       92±7*                  36±2*

x            150g     136±7                    57±2

x            250g     175±11                  79±4

y             50g       99±7                    43±4

y           150g     191±7                     75±3

y           250g     240±16                   96±3

z            50g      64±4                      31±3

z           150g     116±8  │**             43±4│ **

z           250g     130±12│                 52±4│

* Mean ± SEM (N=8).

** Values connected by lines do not differ significantly (p>0.05) as determined

by Student Newman-Keuls analysis.

Conclusion: The force with which a toothbrush is used has a significant effect on the RDA value; the magnitude of the effect is significantly affected by both the brush design and paste type. The results clearly indicating that brush bristle array design together with likely usage force can have a significant effect on the abrasion potential of a toothbrush.