Resin infiltration is a new technique to stop the development of early enamel caries, which bridges the gap between caries prevention and treatment, and caries infiltration provides minimally invasive treatment for non-cavity lesions on smooth surfaces and adjacent surfaces, avoiding unnecessary loss of healthy hard tissues around caries caused by surgical treatment. Therefore, early caries cannot just observe and wait until the cavity is formed, while filling after grinding the tooth tissue, but stopping the development of caries with infiltrating resin. Early enamel caries is clinically manifested by the appearance of chalky spots, and its typical pathological damage is that the superficial layer of enamel is relatively intact while the subsurface demineralization is severe. The clinical treatment plan for this type of lesion is to use fluoride to promote remineralization, oral hygiene promotion and reasonable dietary control, however, these treatments are not always effective in patients with progressive caries and poor compliance. Just like the vault sealants act on the jaw surface of the molar teeth, they can be effective in preventing the progression of caries. Whereas traditional den sealing produces a barrier on the enamel surface, the infiltration technique produces a barrier inside the lesion. The penetrating resin is applied by capillary action, i.e. the liquid (light-curing resin) penetrates into the porous solid (carious enamel) by capillary forces. It is like a sponge absorbing water. The penetrating resin should have an extremely high permeability coefficient in order to enter the tiny pores of the subsurface lesion, completely filling and stopping the diffusion of nutrients and the progression of caries. The resin that plugs and fills the micro-pores forms a barrier within the carious lesion, replaces the loss of hard tissue due to demineralization, and strengthens the enamel structure and prevents the enamel surface from disintegrating and forming cavities, but it does not change the anatomical form and appearance of the tooth, and this technique is particularly suitable for smooth surface and adjacent surface caries. This technique is particularly suitable for smooth surface and adjacent surface caries because the invasive treatment removes a large amount of healthy dental tissue in order to gain access to the lesioned area. Indications for infiltrative resin: Infiltrative resin is suitable for non-cavernous caries on adjacent surfaces and smooth surfaces (i.e. early caries located in the superficial 1/3 of enamel and dentin). And it can remove chalky plaque of smooth surface enamel associated with aesthetics, often in demineralization of enamel surface after orthodontic fixed orthodontic appliance is removed. Advantages of infiltrating resin: mechanical stabilization of demineralized material in early enamel caries, preservation of healthy hard tissues (protection of affected and adjacent teeth), permanent plugging of superficial micropores and cavities, can stop caries progression, reduce the risk of recarring decay, delay restorative treatment, no risk of postoperative sensitivity and pulpitis, reduced risk of gingivitis and periodontitis, for lesions with demineralized labial surfaces (e.g. after orthodontic chalky plaque), it can improve the aesthetic results. It is easily accepted by patients and does not require multiple follow-up visits, anesthesia or mechanical abrasion. It is worth noting that the infiltrating resin has no X-ray blocking and the effect of the treatment can be tracked by future review. In conclusion, caries infiltration is a new treatment technique which can effectively stop the progression of early caries on adjacent and smooth surfaces, but it lacks wide clinical application and long-term observation and follow-up.