lip pits (congenital lip fistulas), n.pl the congenital depressions, usually bilateral and symmetrically placed, on the vermilion portion of the lower lip. These pits may be circular or may be present as a transverse slit. The depression represents a blind fistula that penetrates downward into the lower lip to a depth of 0.5 to 2.5 cm. They often exude viscid saliva on pressure.
This resulted in the introduction of three new laser classes (1M, 2M and 3R) and the abolition of Class 3A. Below is a brief description of each of the current laser classes. The 60825-1 standards apply equally to lasers and LEDs. In most places we have used the word laser, but it can be replaced by LED. Generally speaking LEDs would be in the lower Classes (1, 1M, 2, 2M, 3R), but very exceptionally may be Class 3B.
Laser Types The family of CO 2 lasers is very diverse: For laser powers between a few watts and a several hundred watts, it is common to use sealed-tube or no-flow lasers, where the laser bore and gas supply are contained in a sealed tube. Such lasers are compact and rugged, and reach operation lifetimes of several thousands of hours.