IADR Abstract Archives
Working Mechanism of Tooth Whitening Based on Hydroxyapatite Suspended in a P11-4 Peptide Matrix
Objectives:
To evaluate how hydroxyapatite (HAP) suspended in a self-assembling peptide matrix contributes to tooth whitening.
Methods:
In the literature two alternative explanations are offered how HAP contributes to the whitening of teeth: Niwa at al. (2001) suggest that remineralization processes make surfaces of teeth smoother and glossier, while Roveri et al. (2009) propose that a HAP surface layer increases the diffuse reflection of light, which results in a measurable increase in lightness.
10 teeth (shade A3 or darker) were treated with hydroxyapatite suspended in a self-assembling P11-4 peptide matrix (Credentis, Windisch, CH). The monomeric peptides were dissolved in water and an equal amount of 25wt% HAP-suspension was added to the peptide solution. The solution as applied to the surface in a thin homogenous layer. After 5 min loose remnants were washed away. The bidirectional reflectance distribution function (BRDF) was measured with an angular-resolved goniometer before and after the application. The tooth surface was illuminated with a laser at 650 nm (angle of incidence 0°). The light scattered from the tooth (surface and subsurface scattering) was detected with a calibrated HDR CCD sensor (angle of reflectance plus/minus 70°, 5° steps).
Results:
The specular reflection was on average 0.8 relative to the maximum of Spectralon before the application of the HAP/P11-4 mixture. This value dropped to a mean value of 0.5 after the application. The difference was statistically significant (p < 0.05). The diffuse reflection increased after the application of the whitening suspension between 0 and 0.15 relative mean HDR units. This difference was signficant for angles greater then +/- 30 degrees (t-test for each angle).
Conclusions:
The intial whitening effect of HAP-particles dispersed in a matrix of self-assembling peptides can be explained with an increased diffuce reflection of light.
To evaluate how hydroxyapatite (HAP) suspended in a self-assembling peptide matrix contributes to tooth whitening.
Methods:
In the literature two alternative explanations are offered how HAP contributes to the whitening of teeth: Niwa at al. (2001) suggest that remineralization processes make surfaces of teeth smoother and glossier, while Roveri et al. (2009) propose that a HAP surface layer increases the diffuse reflection of light, which results in a measurable increase in lightness.
10 teeth (shade A3 or darker) were treated with hydroxyapatite suspended in a self-assembling P11-4 peptide matrix (Credentis, Windisch, CH). The monomeric peptides were dissolved in water and an equal amount of 25wt% HAP-suspension was added to the peptide solution. The solution as applied to the surface in a thin homogenous layer. After 5 min loose remnants were washed away. The bidirectional reflectance distribution function (BRDF) was measured with an angular-resolved goniometer before and after the application. The tooth surface was illuminated with a laser at 650 nm (angle of incidence 0°). The light scattered from the tooth (surface and subsurface scattering) was detected with a calibrated HDR CCD sensor (angle of reflectance plus/minus 70°, 5° steps).
Results:
The specular reflection was on average 0.8 relative to the maximum of Spectralon before the application of the HAP/P11-4 mixture. This value dropped to a mean value of 0.5 after the application. The difference was statistically significant (p < 0.05). The diffuse reflection increased after the application of the whitening suspension between 0 and 0.15 relative mean HDR units. This difference was signficant for angles greater then +/- 30 degrees (t-test for each angle).
Conclusions:
The intial whitening effect of HAP-particles dispersed in a matrix of self-assembling peptides can be explained with an increased diffuce reflection of light.