A common topic that we often encounter from parents during outpatient clinics and oral health consultations is “what kind of toothpaste is good for children’s caries prevention”. The simple answer is usually “use fluoride toothpaste”. In view of the “fluoride abuse” phenomenon in western countries and the fact that fluoride toothpaste is not yet commonly used in our country, we would like to discuss the problems that may occur in the use of fluoride toothpaste, so as to draw your attention and prevent misinformation and reduce the possible harm caused by fluoride abuse. It is important to note that the use of fluoride is not a common practice. The discovery of the anti-caries effect of fluoride has led to the use of fluoridated water, fluoridated milk, and fluoride toothpaste to prevent caries. Although the use of fluoride toothpaste has reduced the incidence of caries, the incidence of dental fluorosis in some areas is on the rise. Fluorosis is often caused by excessive intake of fluorine in preschool children, mainly manifested as the change of enamel surface transparency, white plaque, and in serious cases, enamel defects on tooth surface may occur. 1. Why does the abuse of fluoride toothpaste cause dental fluorosis? The safe daily intake of fluoride for children is 0.05~0.07mg/kg, and 65%~70% of children using fluoride toothpaste come from fluoride toothpaste. The intake of fluoride when using fluoride toothpaste varies from person to person and is subject to personal habits; at the same time, the swallowing system of children at this stage is not fully developed, so it is easy to swallow toothpaste by mistake when brushing teeth, which increases the intake of fluoride. If fluoride toothpaste is not used properly, the total fluoride intake will exceed the safe range and lead to dental fluorosis. 2. What is the evidence of increased fluoride intake in children due to the use of fluoride toothpaste? Fluoride intake is associated with toothpaste accidental swallowing during toothbrushing in preschool children. Children’s swallowing systems improve with age, and the younger children start using fluoride toothpaste, the greater their accidental swallowing, leading to increased fluoride intake. Studies have shown that children aged 1 to 2 years swallow 70% to 75% of the amount of toothpaste used each time, and the rate of swallowing gradually decreases with age. Foreign studies have found that children generally swallow 65% to 70% of the amount of toothpaste used during toothbrushing, and these swallowed amounts account for about 70% of the total daily intake. By studying the 24-h urinary fluoride changes in children before and after using fluoride toothpaste, it was found that the urinary fluoride increased after using fluoride toothpaste, indicating that fluoride toothpaste did increase the fluoride intake of preschool children. In addition, the study found that the more toothpaste used, the greater the fluoride intake, and the amount of fluoride swallowed was related to the amount of toothpaste used. 3.How to use fluoride toothpaste correctly? (1) Age of using fluoride toothpaste The age of 1 to 2 weeks is an important period for the development of permanent tooth embryos. Excessive intake of fluoride at this stage will directly affect the shape and structure of the first permanent molar and front teeth, and the amount of accidental swallowing at this stage is very large. By the age of 3 years, most permanent teeth are no longer affected by fluoride and are no longer at a high risk for fluorosis. Therefore, it is generally recommended to start using fluoride toothpaste for children older than 3 years old. (2) Amount of toothpaste The amount of toothpaste used for children between the ages of 6 years old is about the size of a soybean (0.12-0.25mg), and the amount of toothpaste can be increased appropriately as children get older. (3) Fluoride concentration The quality concentration of fluoride toothpaste for preschool children is controlled at 500-550mg/L. Some people think that the low concentration of fluoride cannot achieve the ideal caries prevention effect, but some studies have confirmed that the caries prevention effect of fluoride toothpaste with the quality concentration of 500mg/L, 1000mg/L and even 2000mg/L is similar and there is no great difference, so there is no great difference in the same caries prevention function. Therefore, it is safer to use low concentration of fluoride toothpaste under the premise of the same caries prevention function. (4) Rinsing after brushing The teeth in the mouth of preschool children are mostly milk teeth, and the cervical part of milk teeth is obviously contracted compared with permanent teeth, and there are physiological gaps in the milk teeth, which can easily lead to the accumulation and residue of fluoride toothpaste in these parts. It has been found that rinsing after brushing can reduce the residue of toothpaste in the mouth and indirectly reduce the fluoride intake, so it is recommended that preschool children should rinse their mouths after brushing to reduce fluoride intake. (5) Parental supervision Preschool is a critical stage in the development of toothbrushing habits, and parents play a decisive role during this period, and their supervision and guidance directly affects children’s fluoride intake. Existing studies tend to recommend that parents be involved in the entire process of children’s brushing, including helping to calculate toothpaste dosage, squeezing toothpaste, advising children not to swallow toothpaste, and supervising mouth rinsing after brushing. (6) Other issues The widespread use of fluoride pesticides in agriculture has led to increased fluoride levels in fruits, and soft drinks and juices produced from these fruits also contain high levels of fluoride. This means that even in non-fluoridated areas, consumption of large amounts of soft drinks can lead to additional fluoride exposure, and parents should take these factors into account. Fluoridated toothpaste should be avoided in high fluoride areas due to higher than normal water fluoride concentrations; fluoridated toothpaste is appropriate in low and moderately fluoridated areas. In conclusion, the use of fluoride toothpaste is potentially dangerous for preschool children, and to reduce or avoid the occurrence of dental fluorosis, fluoride toothpaste must be used safely and reasonably. How to make full use of the benefits of fluoride toothpaste depends mainly on individual brushing habits and parental supervision. It is also important to choose the correct age to start using fluoride toothpaste and to control the amount of toothpaste used.