The Intraoral Study On The Stability Of Two Colorimeters

Objective:Matching the left natural maxillary central incisor of ten subjects withtwo shade-macthing instruments (OLYMPUS Crystaleye and Vita Easyshade) by eighttesters,to analyse the difference between the two instruments from differenet testers anddifferent test time,to evaluate the stability of each instruments and the consistency of thetwo instruments’ stability.The result of this study will provide the theory basis abouthow to choose the methods and tools in clinical shade-matching.Methods: Color parameters of the healthy left natural maxillary centralincisor(middle1/3) of ten subjects were measured with the two shade-matchinginstrumens by eight prosthodontists who have worked on clinical prosthodontics forthree years at least.Test process is as follows:on the first day of the test,each subject wasmeasured by each tester three times to collect a total of nine color parameters,and recordeach group of color parameters with the L~*,a~*,b~*values.These operatings were repeatedon the third day and the sixth day. Calculate the mean,standard deviation and95%confidence interval of the nine color parameters.And the mean of nine color parametersrepresent the measured values of each day included in the analysis, the upper and lowerlimits of the95%confidence interval as the values of the formula⊿E=[(L1~*-L2~*)2+(a1~*-a2~*)2+(b1~*-b2~*)2] to calculate the color difference⊿E.Usingthe analysis of variance of spss11.5statistical analysis software to analyze the twoinstruments in their respective differences among different dentists and different times.Analyse the stability between the two shade-matching instruments by making the twoinstruments measured L~*,a~*,b~*value for paired T-test.Results:1. The L~*,a~*,b~*values measured by the OLYMPUS Crystaleye and thecaculated color difference⊿E between different densists and different times are not significantly different（P>0.05）. The L~*,a~*,b~*value measured by the Vita Easyshadebetween different densists and different times are not significantly different（P>0.05）,but the caculated color difference⊿E between different densists anddifferent times are significantly different（P>0.05）.2. The result of the paired T-test between the two different shade-matchinginsturments are significantly different（P>0.05）.3. The mean of the color difference⊿E measured by OLYMPUS Crystaleyeis1.36nbs,and the mean of the color difference⊿E measured by Vita Easyshade is3.16nbs.Conclusion:1. Under the present experimental condictions,the stability ofOLYMPUS Crystaleye spectrophotometer is good,2. Under the present experimental condictions, the measurement result of VitaEasyshade spectrophotometer is easily to show greater volatility.3. The consistency between the two spectrophotometers’ stability is low.4. Under the present experimental condictions,the stability of the OLYMPUSCrystaleye spectrophotometer is better than the stability of Vita Easyshadespectrophotometer.