Einfluss von verschiedenen Lagerungsmedien auf Fluoreszenzmessungen an Zähnen - eine In-vitro-Studie

Aim: The aim of the present in vitro study was to determine the influence of three different storage media on the fluorescence behavior of carious lesions over a period of four weeks. In addition, the classification of the fluorescence readings was examined for its evidence according to the literature. Furthermore, the correlation between the fluorescence-based measurement using the VistaCam iX® (VC iX) and the visual findings of the International Caries Detection and Assessment System (ICDAS) was investigated. Materials and methods: The 72 extracted posterior teeth were carefully cleaned and evaluated by using the ICDAS codes. According to these codes, an equal number of teeth was then assigned to each of the three storage groups (distilled water, chloramine-T, freezing at -20 °C). The teeth were measured at baseline, after one week and after four weeks using the VC iX and its corresponding proof interchangeable head. The determined data was transferred to a spreadsheet program (MS Excel) and statistically evaluated using MedCalc version 19.1.7. The correlation between the findings of the ICDAS examination and those of the fluorescence measurement were listed in cross tables and evaluated with the rank correlation coefficient in accordance with Spearman (rs). The Kruskal-Wallis test and the Friedman test were used to evaluate whether there were differences between the individually measured values overall and the individual bearing groups over time. The results were presented and evaluated in Bland-Altman diagrams and box plots. Results: The correlation of the visual findings (ICDAS) with the fluorescence-based measurements (VC iX) is statistically significant positive in a high range (rs = 0.76). As for the individual storage media, a positive, partially high significance between the results is apparent: distilled water (rs = 0.85), chloramine-T (rs = 0.77), freezing at -20 °C (rs = 0.69). The evaluation of the Kruskal-Wallis test does not show significant differences in the VC iX measurement results between the three measurement points, neither for the individual values nor for category formation (individual values: baseline: p = 0.62; 1 week: p = 0.42; 4 weeks: p = 0.61). In the evaluation of the Friedman Test, no statistically significant differences were found within the measurement period for the measurement results of teeth in distilled water (p = 0.16) and those of frozen teeth (p = 1.00). The evaluation of the Friedman test for category formation did not show significant differences for distilled water (p = 0.08) or for freezing at -20 °C (p = 0.14). The evaluation of the Friedman test for the storage medium chloramine-T showed statistically significant differences between the measurement results within the three test full stops (p < 0.05) and also for category formation (p < 0.05). The Bland-Altman plots for the comparison "baseline vs. after 1 week" show the following mean values (with "limits of agreement"): Total: 0.03 (-0.31 – 0.37); distilled water: 0.03 (-0.32 – 0.38); chloramine-T: 0.08 (-0.25 – 0.40); freezing at -20 °C: -0.01 (-0.35 – 0.33). The comparison of the results "baseline vs. after 4 weeks" shows the following mean values (and "limits of agreement") per group: Total: 0.11 (-0.38 – 0.60); distilled water: 0.10 (-0.38 – 0.58); chloramine-T: 0.20 (-0.40 – 0.80); freezing at -20 °C: 0.03 (-0.27 – 0.32). For the time comparison "after 1 week vs. after 4 weeks", the following mean values (with the “limits of agreement”) could be determined: Total: 0.08 (-0.37 – 0.52); distilled water: 0.07 (-0.48 – 0.61); chloramine-T: 0.13 (-0.31 – 0.56); freezing at -20 °C: 0.03 (-0.29 – 0.36). Discussion and conclusion: The results of this study show a high correlation between VC iX and ICDAS. Differing results between the two methods were found, especially in the area of teeth with initial lesions. The VC iX can thus be used in clinical caries diagnostics as a tool complementary to and supportive of conventional, validated methods such as ICDAS. With regard to storage media, long-term storage in chloramine-T can be advised against in regards to subsequent studies on extracted teeth with a focus on fluorescence-based investigations of carious lesions. However, a recommendation can be made for storing the teeth in a frozen state at -20 °C or in distilled water.