The resin of the filling itself does not melt, but it is also very difficult to reach the condition of complete moisture isolation and very dryness in our oral cavity, so that micro-leakage occurs during and after the filling. The filling materials currently used in our first-line clinical applications are developed by high-tech companies over the years, which themselves have good aesthetic as well as biocompatibility, while not dissolving in water or easily salivated. Once the filling material itself dissolves, it will inevitably cause food embedding and secondary caries, which is unacceptable to the development company. Therefore, for the filling material itself, patients should not have the doubt that it can be melted, but we require our tooth surface to be absolutely dry when filling, in the actual clinical work, due to the saliva in the mouth or some of our water vapor environment, it will cause more or less slight dampness in the mouth. This situation will act between the filling material and the tooth surface in the process of filling, and form micro-leakage between the filling material and the tooth surface, thus the possibility of food embedment and secondary caries. Therefore, the filling material itself will not melt, but there is a possibility of microleakage due to the operation.