A new method for quantitative intra-oral tooth color determination is presented. Basically, the tooth color is assessed by visual comparison with opaque color standards, which are logically arranged according to three visual color dimensions. The standards were analyzed spectrophotometrically, and the C.I.E. color coordinates were computed. Illumination and observation were standardized during the matching procedure. Two distinct situations, method 1 and method 2, were investigated. The situation in method 1 is to be considered as large window illumination and small window collection of the reflected light. For method 2, the same small window was used for both illumination and observation. Using both methods, the color of a tooth could be quantified into three separate color dimensions. Using method 1, the consistency among 25 examiners was high in determining the color of ten teeth; using method 2, the inter-examiner agreement was low. For the same tooth, different color standards were selected with method 1 or method 2. The standard selected with method 2 often appeared to be in disagreement within clinical expectations. The differences in results between method 1 and method 2 are explained by the optical properties of the translucent dental enamel (e.g., volume reflection). Method 1 allows for reproducible quantification of clinical tooth discoloration according to C.I.E. color specifications and can possibly be applied in prosthetic dentistry.
An optical instrument is described which quantitates incipient smooth surface caries lesions in vivo. The possible role of such quantitation in caries management and in clinical caries research is discussed. The instrument uses a bundle of small fibres in an ‘optical needle’ with a flat end that is placed on the lesion. Half the fibres are used to illuminate the lesion and the other half to collect the light backscattered by the lesion interior. In this geometry, lesions reflect much more light than does sound enamel. The instrument has been validated against natural lesions in extracted teeth, and the depth of these lesions and their mineral loss were measured by microradiography. The correlation coefficient between these two parameters was 0.96 and the correlation between optical measurement and lesion depth 0.71.
The optical caries monitor is a nondestructive method to quantify light scattering in bulk dental enamel and early carious lesions. This paper describes a fiber-optic version of the instrument which potentially may be used in the mouth. It is compared with the calcium loss from softening and subsurface type in vitro lesions in bovine enamel. Calcium loss is determined by both chemical methods and microradiography. The results show that the monitor correlates well (r =0.94) with calcium loss, independently of the type of lesion. Variations within and between teeth found with the three methods demonstrate a large spatial inhomogeneity in calcium loss (= 25%) within a lesion of any of the two types.
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