Special Laser-induced Fluorescence System For Dental Calculus Diagnosis

Periodontitis is the chronic, non-heterosexual, infectious diseases of the dentaltissue (including the cementum, periodontal ligament, alveolar bone and gums).Globally more than80%of the population will be affected by this disease. In China,more than50%of the extractions are caused by periodontitis. The deterioration ofperiodontitis could easily lead to or even exacerbate other diseases, such as lunginfections, coronary heart disease and diabetes. In this paper, we selected a635nmsemiconductor laser as a light source, studied and implemented dental calculuslaser-induced fluorescence diagnostic system, as follows:Firstly, we developed a dental calculus fluorescence diagnostic system todetermine the diagnostic criteria. Experimentally, a standard judging parameterR S(618648)S(650730)was selected to determine whether there is a dental calculus.Experimental statistically indicated there is a significant difference (P <0.05) betweenthe normal teeth and the teeth with dental calculus. It is found that the sensitivity andaccuracy could reach99%and93.3%, respectively, when R=0.9was selected as thediagnostic threshold for dental calculus.Secondly, the spectra were analyzed. It is concluded:(1) the numbers of fluorescentphoton from different calculus are different;(2) the shape of the fluorescence spectralfrom a vitro teeth is determined by the contents ratio of fluorescence biologicalmolecules;(3) the fluorescence peak from the brown calculus is a little bit higher thanthat from the yellow calculus. Some factors may affect the diagnosis accuracy. Forexample, calculus may be generated by bacteria groups on the artificial teeth. However,the fluorescence intensity from a real toothis stronger than that from an artificialone.The exact reason for that still needs to be studied. A large number of artificial teeth aremade from play Polymethyl Methacrylate material, which may also have some effect onthe diagnosis accuracy. As long as the thickness of teeth in the lateral defect is no lessthan3mm, the influence of dental calculus diagnosis can be neglected, if the thicknessof teeth in the longitudinal direction is greater than2mm, the influence of dentalcalculus diagnosis can also be neglected. An optimal laser power range from19mw to59mw has determined to measure dental calculus; meantime, the best fluorescence receving distance of less than2mm is recommanded.Rhodamie b on the dentalcalculus has a much stronger stranded effect than that on the normal teeth. Thus,fluorescence spectra produced by photosensitizer could can be used in thediagnosis ofdental calculus, which provides a very good way for clinical diagnosis.Finally, an automatic measurement software fordental calculus diagnosis systemare programmed. Software includes menus, toolbars, status bar, graphic display area,user control area and other parts. Moreover, it provides many convenient functions, suchas automatic measurement, spectra display in real time, data saving, patient informationand parameter settings. It can also calculate and display canned spectra dates. Comparedwith the old manual date-collecting method, the software can synchronize the datecalculation with collection. A touch panel display is adopted to improve and perfect thissystem, which provide a quick and convenient control platform for the equipmentoperators.