Title: Objective and Quantitative Assessment of Caries Lesion Activity Short Title: Objective Caries Lesion Activity Assessment

Objectives: Evaluate the ability of objectively measured specular reflection, roughness, and fluorescence change during dehydration to assess caries lesion activity. Methods: One hundred ninety-five ground/polished 3x3x2mm sound human enamel specimens were divided into three groups and demineralized using a multispecies microbial caries model for 3, 6, or 9 days; and then remineralized with 1,100 ppm-F as NaF solution for 10 days using a pH-cyclic model. Reflection (amplitude: %), roughness (Ra: μm), fluorescence change during dehydration (ΔQ: %mm), and microfocus computed tomography [μ-CT: lesion volume (μm)] were measured for sound, demineralized and remineralized enamel. The surface was hydrated and fluorescence images were acquired at 1s intervals for 10s (ΔQ10). During image acquisition, surface was dehydrated with continuous compressed air. Changes-in-ΔQ per second (ΔQD: %mm/sec) at 5 (ΔQD5) and 10s (ΔQD10) were obtained. Results: Reflection decreased from sound to AC CE PT ED M AN US CR IP T ___________________________________________________________________ This is the author's manuscript of the article published in final edited form as: Ando, M., Fontana, M., Eckert, G. J., Arthur, R. A., Zhang, H., & Zero, D. T. (2018). Objective and quantitative assessment of caries lesion activity. Journal of dentistry. https://doi.org/10.1016/j.jdent.2018.08.009 demineralized groups (p<0.0001); remineralized groups were higher than demineralized groups (p<0.001), but not different from sound (p>0.32). Roughness increased from sound to demineralized groups (p<0.0001) and remineralized groups were also higher than sound (p<0.0001). ΔQ10, ΔQD5 and ΔQD10 increased from sound to demineralized groups (p<0.0001), and remineralized groups decreased compared to demineralized groups (p<0.05), but was higher than sound (p<0.0001). The correlations of μ-CT with reflection, roughness, and ΔQ10 were -0.63, 0.71, and 0.82, respectively (p<0.0001). Conclusions: Reflection, roughness and ΔQ could distinguish between sound and demineralized enamel. Reflection and ΔQ were able to distinguish between demineralized and remineralized enamel. Clinical significance: Determination of caries activity, whether a lesion is active or inactive, is an essential and critical component of caries diagnosis. However, especially for enamel lesions, it is difficult to estimate without longitudinal follow-up. Reflection, roughness and fluorescence change during dehydration have the potential to measure caries lesion activity at a-single-appointment.