Difference based on shape and volume. Generally speaking, deciduous teeth are smaller in size and have narrower tooth surfaces, while permanent teeth are wider. The crowns of newly erupted permanent teeth are larger than those of the deciduous teeth with the same name.

Judging based on the number of teeth. The teeth of children around 12 years old are in the mixed dentition stage, with both deciduous teeth and newly erupted permanent teeth in the mouth. Count five from the middle gap between the upper and lower front teeth to each side, from one to twenty, which are the deciduous teeth. Normally, there are ten deciduous teeth at the top and bottom. Permanent teeth generally have 28-32 teeth.

Judge based on color. The deciduous teeth are white and the permanent teeth are slightly yellow. This is because the enamel of permanent teeth is more calcified and more transparent than the enamel of deciduous teeth, and the yellow color of dentin is transmitted through. Permanent teeth appear glossier than deciduous teeth.

Judge based on the size of the gap between teeth. Generally speaking, the gaps between deciduous teeth are larger and the gaps between permanent teeth are smaller. Deciduous teeth have clear boundaries between crowns and roots, while permanent teeth have almost invisible boundaries.

It can be judged based on the degree of wear on the occlusal surface of the teeth. Because deciduous teeth erupt early, the wear of the occlusal surfaces of deciduous teeth is more serious than that of permanent teeth. However, the permanent teeth have just erupted and the occlusal surfaces have not yet been worn or are slightly worn. Because deciduous teeth are not as strong as permanent teeth and have less calcification, they are used for a longer period of time and therefore wear more seriously.

Although there are many methods of differentiation mentioned above, some teeth may not be clearly distinguished. If it involves tooth extraction, it must be finalized by a doctor. Once the permanent teeth are extracted, they cannot be distinguished again. If it grows out, then it will be too late to regret.