Sebaceous gland the hair shaft. The structure consisting of hair, hair follicle, arrector pili muscles, and sebaceous gland is an epidermal invagination known as a "pilosebaceous unit". Sebaceous glands are also found in hairless areas (glabrous skin) of the eyelids, nose, penis, labia minora, the inner mucosal membrane of the cheek, and nipples. Some sebaceous glands have unique names. Sebaceous glands on the lip and mucosa of the cheek, and on the genitalia, are known as Fordyce spots, and glands on the eyelids are known as meibomian glands. Sebaceous glands of the breast are also known as Montgomery's glands. Sebaceous glands are
Dental sealant that resin could be bonded to enamel through acid etching, increasing adhesion whilst also creating an improved marginal integrity of resin restorative material. It was this bonding system that lead to the future successful creation of fissure sealants. In 1966, E.I. Cueto created the first sealant material, which was methyl cyanoacrylate. However, this material was susceptible to bacterial breakdown over time, therefore was not an acceptable sealing material. Bunonocore made further advances in 1970 by developing bisphenol-a glycidyl dimethacrylate, which is a viscous resin commonly known as BIS-GMA. This material was used as the basis for many resin-based sealant/composite material