Sebaceous gland Sebaceous gland Sebaceous glands are microscopic exocrine glands in the skin that secrete an oily or waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals. In humans, they occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. The type of secretion of the sebaceous glands is referred to as holocrine. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Fordyce
Dental sealant issue with resin based sealants than with glass ionomer sealants. The surface is cleaned and dried. Resin sealants require an phosphoric acid solution ("etch") to create microscopic porosity into which the sealant material can flow thereby increasing retention, increasing surface area and improving the strength of the bond between the sealant and the tooth surface. Etching time varies from 15 to 60 seconds, depending on the product. After that, the tooth must be rinsed and dried thoroughly for 15 to 20 seconds. Chalky appearance on the dried tooth means the tooth has been properly etched. If the tooth does not