There are advantages and disadvantages of all filling materials. Glass ion has been used for filling teeth since more than 20 years ago, the disadvantage is that the bonding is not strong, so it is easy to fall off, and the strength of glass ion is not high, so it is likely to break or wear out too much during the process. However, glass ions still have advantages and irreplaceable, because glass ions will slowly release fluoride ions after filling, therefore, it can prevent the occurrence of caries, and it is very suitable for filling milk teeth, because children have lower biting force, which precisely circumvents the weakness of glass ions that are not wear-resistant. Glass ion has a certain soothing effect on the pulp without any irritation, so it can be used for the bedding of deep caries, called sandwich technique.