http://www.saudident.com/album/data/media/17/The_bleaching_of_teeth-A_review_of_the_literature.pdf

The bleaching of teeth: a review of the literature.

Tooth colour : a review of the literature

Color measuring systems and methods are disclosed. Perimeter receiver fiber optics are spaced apart from a central source fiber optic and receive light reflected from the surface of the object being measured. Light from the perimeter fiber optics pass to a variety of filters. The system utilizes the perimeter receiver fiber optics to determine information regarding the height and angle of the probe with respect to the object being measured. Under processor control, the color measurement may be made at a predetermined height and angle. Various color spectral photometer arrangements are disclosed. Translucency, fluorescence and/or surface texture data also may be obtained. Audio feedback may be provided to guide operator use of the system. The probe may have a removable or shielded tip for contamination prevention.

Apparatus and method for measuring optical characteristics of an object

Due to interhuman differences in the perception of color, visual shade assessment of human teeth is lacking standardization that may be improved by the use of a spectrophotometer. In this study, we tested the hypothesis that spectrophotometric assessment of tooth color is comparable with human visual determination. On 30 patients, three operators with unreported visual color deficiency independently selected the best match to the middle third of unrestored maxillary central incisors, using a Vita Classical Shade Guide. The same teeth were measured by means of a reflectance spectrophotometer. In the human group, all 3 visual shade selections matched in only 26.6%. In the spectrophotometric group, all 3 shade selections matched in 83.3%. In 93.3%, Delta E values of visually assessed tooth shades were higher than spectrophotometrically assessed Delta E values (p < 0.0001). The results suggest that spectrophotometric shade analysis is more accurate and more reproducible compared with human shade assessment.

Visual and Spectrophotometric Shade Analysis of Human Teeth

The purpose of this study was to evaluate the discoloration of two nanohybrids, two microhybrids, and a posterior composite resin restorative material upon exposure to different drinks — namely tea, cola, coffee, red wine, and water. The colors of all specimens before and after storage in the solutions were measured by a colorimeter based on CIE Lab system, and the color differences thereby calculated. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's HSD test. According to ANOVA, the restorative material, staining agent, and their interaction were found to play a statistically significant role (P=0.0001) in color change. Among the staining agents, water consistently showed the lowest ΔE* value for all materials, whereas red wine showed the highest ΔE* value. In other words, for all the materials tested, their color change in staining agents ranked in this increasing order: water < cola < tea < coffee < red wine. In terms of comparison among the five restorative materials, Filtek P60 and Z250 were observed to manifest less color change than the nanohybrids and Quadrant LC.

/pdf/color-stability-of-resin-composites-after-immersion-in-3yl76m8hnm.pdf

Color stability of resin composites after immersion in different drinks.

Tooth color is caused by volume reflection, that is, passage of incident light through the tooth followed by backward emergence. This passage is concurrent with sideward displacement of photons that, in effect, influences the result of usual instrumental methods of determining tooth color. This problem is overcome by the use of large-field illumination and small-field observation. A fiber-optics colorimeter based on this principle is described. The color observed through two holes in a double box was visually matched by subtractive adjustment of the illuminating color in one box, whereas the other box showed the central part of the tooth diffusely illuminated by illuminant C light. This colorimeter was tested on wet, extracted human incisors in the tooth arch of a phantom-head. Results were compared with a visual standard-strip method described previously and with a conventional spectrophotometer. It was concluded that the fiber-optics colorimeter is a promising instrument, although technical improvement is necessary.

A comparison of new and conventional methods for quantification of tooth color

MEASUREMENT OF REFLECTIVITY AND COLOR OF TRANSLUCENT MATERIALSJ.J. ten Bosch, P.C.F. Borsboom, T. van der Burgt and W. KortsmitDental School, Univ. of Groningen and Dental School, Univ. of NijmegenThe NetherlandsAbstractThis paper discusses the error made when measuring the color of translucent materials,using the same window for illumination and light collection. Two methods, based on large -window illumination and small -window collection are described.IntroductionNon- luminous objects are seen because they reflect light. Usually volume reflectionis the predominant process. It means that the illuminating light enters the material,is scattered by scatterers inside, and leaves the material through the illuminated surface1.Color is caused by absorption inside the material, although wavelength- dependence ofscattering may contribute to color as well. An individual photon follows a random paththrough the material and so it emerges at the surface at a certain sideward distance fromthe place where it entered the material. This fact has consequences for measurement ofreflectivity and color.Reflectivity and color are commonly measured with the same window for illuminationand collection. The photons entering near the boundary of the window may travel so farinside the material that they emerge beyond this boundary and thus are excluded fromthe measurement (Figure 1).

W.J.P.M. Kortsmit

Papers

A comparison of new and conventional methods for quantification of tooth color

of Groningen and Dental School, Univ. of Nijmegen