Decay does not affect all tooth surfaces equally. Rather, some surfaces of the teeth become more decayed due to their special condition. These surfaces are:
Grooves on the chewing surface: The chewing surface of the molars contains narrow and deep grooves that provide a suitable environment for germs to grow and multiply, and tooth decay occurs from this site.

This happens especially in the molars, which can lead to early decay.
Interdental surfaces: This area also cannot be cleaned because the toothbrush does not reach it, so it is considered one of the areas most susceptible to decay and gum disease.
Where the gums connect with the teeth: The accumulation of germs in this place usually leads to gum disease.