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Publications (2)5.68 Total impact

  • Thomas Kocher, Natascha Langenbeck, Michael Rosin, Olaf Bernhardt
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    ABSTRACT: In comparing and evaluating the instruments that are used in root debridement, roughness constitutes a standard variable that is assessed. The purpose of this study was to describe the conditions and requirements for the three-dimensional roughness measurements of tooth roots using a laser profilometer. Impressions were made of 60 instrumented and 12 untreated root surfaces, which were then measured using a dynamically focussing optical profilometer (Mikrofocus, UBM, Karlsruhe, Germany). To separate roughness from the form of the tooth, a low pass filter was applied. This meant that the longer wavelengths - which roughly approximated the root forms - were subtracted from the measured profile. We then used an individualized Fourier transformation to define the threshold at which roughness becomes waviness. Roughness parameters were Ra (average roughness) and Rz (average roughness in the z dimension) for two- and three-dimensional measurements. To describe the requirements for the measurement, we studied the effect of pixel density and the field size on the average roughness value, Ra. We found that Ra increases with pixel density until 400 per mm is reached, after which it does not change meaningfully. Furthermore, Ra is highly dependent upon the area of the field to be scanned, increasing in line with the area, and does not approach one value within the surface available on one tooth. The correlation coefficients between the two-dimensional and three-dimensional Ra and Rz values ranged from 0.7 to 0.8. We conclude that roughness values are strongly dependent on the measurement conditions and the results of one study cannot be directly compared to another. In addition, it was found that two-dimensional measurements are sufficient for characterizing root surfaces.
    Journal of Periodontal Research 05/2002; 37(2):125-31. · 1.99 Impact Factor
  • T Kocher, M Rosin, N Langenbeck, O Bernhardt
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    ABSTRACT: To assess the root surface roughness and topography on extracted teeth using different instruments. In the present study, laser profilometry was used to examine the 3-D roughness values Ra and Rz and topography of root surfaces of periodontally-involved teeth instrumented in vivo with curette, conventional ultrasonic device, conventional or teflon-coated sonic scaler insert, or the Periotor instrument (12 teeth per instrument type), and compare these with uninstrumented cementum surfaces. The roughness values Ra and Rz of the roots treated with the different instruments showed a similar pattern: curettes and the Periotor instrument produced the smoothest surfaces (Ra about 1.5 microm, Rz 30 microm); the 4 other instruments created similar Ra values of approximately 2-3 microm and Rz roughness of about 50-70 microm, which equals the untreated root surface. For Ra, the difference between the curette or the Periotor instrument and the teflon-coated sonic insert or ultrasonic insert was significant, and for Rz, a significant difference was found between the curette or the Periotor instrument and ultrasonic insert. As opposed to surfaces debrided with the Periotor and teflon-coated sonic scaler, it appears that hand instruments markedly reconfigure surfaces. The lowest root-surface roughness values were obtained with hand instruments. The teflon tubing on the sonic scaler insert effected no change of topography or roughness as compared to uninstrumented, control surfaces. However, it must be pointed out that hard-tissue removal was not investigated.
    Journal Of Clinical Periodontology 09/2001; 28(8):723-9. · 3.69 Impact Factor