When you find a little bit of tooth decay, you should go to the hospital to check the depth of the decay, which is categorized into shallow, medium and deep caries. Shallow caries can be considered as non-surgical treatment, while medium and deep caries need to be filled after removal of the decay. 1. Shallow caries. For early caries, fluoride medication can be taken, remineralization treatment can be used to make the carious environment disappear or the demineralized enamel remineralized by artificial methods, or osmotic resin can be used to terminate the early caries by infiltrating into the pore space of demineralized enamel through siphoning effect. 2. Medium and deep caries. For caries that is clinically visible to the naked eye, its internal caries may be very large after de-rotting with instruments, and it is usually necessary to use glass ionomer or resin to fill the cavity after removing the decayed tooth tissue. When a little bit of tooth decay is found, it is recommended to go to the hospital as soon as possible to avoid deepening of caries to trigger pulpitis or apical periodontitis.