Research On The Measurement System Of Teeth Whiteness

With the development of the economy and the improvement of human life,more and more people begin to smoke, drink tea, coffee and other colorful beverageswith an increasing frequency. Not only the human health problem grows with eachpassing day, but also the health and the beauty of teeth color appearance. How toachieve a fast measurement of teeth color to ensure the accuracy and consistence ofthe colorimetric has been paid attention for a long time. Therefore, a teeth colormeasurement system which is portable, small and with moderate price has become arequirement for dental diagnosis.In this paper, a portable dental instrument which is used for measuring thewhiteness of the teeth is designed. It is based on the spectrophotometric principle,and it uses whiteness as the standard to evaluate tooth color. This will help to choosea tooth shade color with a good consistence. The specific work includes:(1)Optical system. Based on the relationship between the whiteness and colortristimulus values, we try to get the teeth whiteness by the measurement of teethtristimulus values. In the aspect of optical structure, choose the appropriate lightingsource， and use the reflective and Y-shaped optical fiber probe to realize thetransmission of light; based on the spectrophotometric principle, choose anappropriate spectroscopy system structure, choose to use the flat-field concavegrating; choose an appropriate CCD detector to detect the spectrum signal. Finally inorder to minimize the volume of the system and fulfill the above requests, choose touse the UM1000spectrum module to be the core of the optical system.(2) Hardware part. This system chooses the32-bits enhanced microprocessorSTM32103ZET6as the main chip to control the hardware circuit, drive the linearCCD to work. According to the typical application of chips, design+5V、-5V and3.3V regulator buck circuit to finish the power supply of kinds of control boards andspectroscopy CCD detector; design the A/D transferring circuit to improve theaccuracy of the measurement. In the meantime, in order to facilitate the PC forsignal transmission, design the RS-232and USB transmission interface. (3) Software part. Finish the design of drive software of microprocessor and PCto produce the CCD drive signal. Program the relative procedure to finish thecommunication protocol and the control the integral time of the CCD drive signal toproduce the trigger acquisition signal of AD converter, finish the drive on USB torealize the communication with PC, and finish the operation processing ofparameters such as tristimulus values, chromaticity coordinates and whiteness andthe working interface display design.(4) Use the VITA3D shade guide tooth as the experimental material to do thedata testing to obtain the whiteness value of each shade guide tooth, and propose theappropriate formula which is applied to the teeth whiteness measurement.