The commonly used clinical methods are inadequate for reliable diagnosis of caries lesions until demineralization is established. By the time a reliable diagnosis can be made, the damage is often irreversible, and restorative methods may be necessary to prevent further progress of the lesions. Early detection of the caries lesion would enable the dentist, by using effective prophylactic measures, to provide remineralization and conservation of the tooth substance rather than restoration of the dentition. Attempts to improve traditional methods or to develop new methods of detecting caries lesions have been numerous. Most of the presently used diagnostic methods require visual observation of an optical signal. Reflected light is used tc detect changes in color, texture, and translucency of the tooth substance. The tools required are a bright light source and a mouth mirror. With special methods utilizing drying, magnification, and photography, the sensitivity of the method can be increased. Various optical methods for the detection and quantification of caries will be discussed - for example, fiber optic transillumination, ultraviolet illumination, the use of various dyes, and fluorescent or non-fluorescent substances to enhance the contrast between the carious and the sound enamel. This presentation will focus on the following two methods: (1) a method that uses visible laser light within the blue-green region as the light source to improve signal-to-noise ratio and increase sensitivity for detection of early caries lesions, and (2) a recently developed quantitative method based on the scattering of light by enamel crystals in relation to their surrounding environment. The possibilities and limitations of the different methods will be critically evaluated. In the near future, optical methods for the detection and quantification of early caries lesions will provide efficient tools for reliable evaluation of caries-preventive measures.
Optimization of Intensity Noise Reduction from an Incoherent Light Source Using Gain Saturated Semiconductor Optical Amplifier in a Spectrum-sliced Channel at 2.5 Gb\\S
