Tooth 21: Decoding the Secrets of Your Lower Left First Premolar
Tooth number 21, which is, according to the universal tooth numbering system, the 1st premolar of the lower left quadrant, is often represented as 4 in the FDI World Dental Federation notation. The lower left quadrant consists of: The quadrant starts from tooth 17, which is the 3rd molar of the lower left quadrant. After…