We investigated the ultraviolet (UV) light sheltering effect of two esthetics coating materials (ECM), White Coat^<TM> and Beauti Coat. ECM was coated on tetracycline-containing cement which was then irradiated with UV light. The sheltering effect was evaluated by color changes in the cement. Statistical evaluation using Tukey's test showed that both materials significantly decreased transmission rate. We also investigated the marginal leakage between enamel and the ECM using the dye-penetration method. The Mann-Whitney U-test was used to evaluate the marginal leakage would occur after long-term application of ECM. The coated specimens were divided into three groups for examination. The coating was removed after 24 hours in the first group. In the second group the coating was removed after thermal cycling 500 times. For the third group the thermal cycling was done 1500 times. The specimens were then observed by SEM. We found that although exfoliation had occurred at the interface between ECM and enamel, there was no damage to the enamel.