The Application Of QLF In Clinic Diagnosis And Quantitative Demineralization Analysis

Objective: The objective of this study was:1. To investigate the application of QLF method in the diagnosis of smooth surface caries and the differential diagnosis with wild dental fluorosis.2. To search for new methods quantitatively analyzing complex demineralization of teeth hard tissue.MethodsPart 1: The QLF images of the upper anterior teeth were taken from 314 twelve-year-old students. The characters of all lesion images were investigated, including lesion distribution, appearance, number and relationship with teeth location in arch. The number of tooth displaying alike characters were counted and listed. Subjects were classified into groups based on similarity of lesion characters. The proportion of these groups was calculated. The differential outlinesbetween early caries and mild dental fluorosis was concluded. Part 2 Eighteen extracted teeth samples were collected, cleaned and disinfected. These teeth were bisected mesial-distally with teeth cutter. After numbered from 1 to 18, QLF images of axial surfaces of every half were taken. These samples were etched by 39% phosphoric gel for part surface about 3* 2mm2 and then were taken images by QLF machine again. The after-etched images were reconstructed by Adobe Photoshop software. Both the after-etched images and reconstructed images were quantitatively analyzed. The values of As(lesion area), AFs(the average fluorescence change), Qs(the total mineral loss) were gotten. Descriptive statistics and One-Way ANOVA of these quantitative values were carried out.Results: 1. all the images were classified into three groups: (1)the first group: lesions with single arch or lunate appearance, clear boundary and alike-the-gingival-margin figure. (2)the second group: lesions with two or more linear dispersed which have illegibility boundary and be parallel with incisive margin, with or without dotted zone. (3)the third group: no dark area on teeth surfaces. The proportion of the three groups is 25.2:39.5:35.3, and these lesion characters of these groups are differentiation outlines between initial caries and mild dental fluorosis.2. the quantitative data from the reconstructed and original images show almost no clinic and statistic deference(One-Way ANOVA, P>0.05) Conclusions 1. It is important to differentiate between the initialcaries and mild fluorosis in clinic. As the QLF images exhibited distinct character the differencial diagnosis can be performed by using QLF method2. There is no lesion information loss for the image reconstruction by Adobe Photoshop. The combined application of the Adobe Photoshop and QLF software will broaden the application of QLF to quantify enamel mineral change.