Evaluation and detection of early nail damage caused by nail enamel.

BACKGROUND Many nail cosmetics have components that are considered irritants or allergens. Due to the current clinical assessment limitations, it is often too late to identify nail enamel hazards until they cause disease. Thus, it is essential to investigate effective methods of detecting minor changes and early lesions in nails before they worsen. OBJECTIVES To provide a reliable method to investigate and evaluate nail enamel hazards on nails earlier using ultrasonic equipment. METHODS Eighty-three volunteers with smooth, lustrous nails were enrolled after being clinically examined. The thumbnails and middle nails were evaluated before and after using nail enamel for 2 weeks. Nail health was then assessed using three methods: clinical evaluation, nail surface image analysis, and an ultrasonic device. RESULTS Using clinical diagnostic and imaging methods for analyzing the nail surface showed no visible differences before and after using nail enamel for 2 weeks. However, there was a significant difference in the nails' depth and density (p < 0.001). The depth had increased 10% for thumbnails (about 20 μm), and the density had decreased by 3.0%. As for middle nails, the depth had increased by 9.4% (about 19 μm), and the density had decreased by 3.0%. CONCLUSION The present study provided evidence that nail enamel can significantly irritate hyperplasia and decrease the density of the nails, but detecting that slow process of pathological changes cannot currently be assessed by conventional clinical evaluation and image analysis. Thus, our study provided a practical novel approach for evaluating these visually imperceptible nail changes.