Oral mucosa forms the lining of oral cavity1*. Cheek skin externally
and oral mucosa internally form the boundaries of the oral cavity, which
contains a layer of skeletal muscle in between. Anteriorly the oral mucosa
communicates with the skin and posteriorly with pharyngeal mucosa21.
Oral cavity is equipped with three distinct types of mucosa that are
specialized, masticatory and lining. All types are bound superficially by
epithelium and immediately beneath the epithelium lies the lamina propria
which forms the bulk of mucosal tissue.
Buccal mucosa (tunica mucosa oris) is formed of lining mucosa.
The epithelium of oral mucosa in humans is stratified squamous non-keratinized.
The thickness of this epithelial layer can vary from 100
pm-500 pm, or 40 to 50 cell thick. This surface is hence rendered flexible
and is able to withstand stretching forces. Histologically, this
non-keratinized epithelium comprises of four basic layers: stratum
basale, stratum spinosum, stratum intermedium and stratum superficiale.
In contrast to humans, the rat buccal epithelium is stratified squamous
keratinized. The keratinized layer is assumed to minimize frictional
damage produced by surface abrasion3*.
Nicotine (C10H|4N2) is a liquid alkaloid comprising of carbon, hydrogen
and nitrogen. It lacks color but it turns brown upon coming in contact
with the atmosphere. Compelling evidence has been brought forth
to prove the harmful effects of these constituents on human health4’.
Cigarette smokers are at a risk of developing cardiovascular disease
(atherosclerosis), lung diseases (lung cancers and chronic obstructive
pulmonary diseases and oral cancer (squamous cell carcinoma)4’.
Nicotine is metabolized in the liver and free radicals are produced
which damage the defense mechanism of body. Free radicals are atoms
or molecules with single unpaired electron in an outer shell. In their
quest to find another electron, they are very reactive and cause damage
to surrounding molecules5’. Expression of pre-osteoblastic cells is
observed in cigarette smoking individuals and the findings indicate that
cigarette smoking inhibits the differentiation of pre-osteoblastic cells6 *’.
Human alveolar bone marrow derived mesenchymal stem cells are evaluated
in order to determine the amount of decrease of alveolar bone
height and failure of implants resulting due to cigarette smoking71.
Nicotine inhibits the mesenchymal cells to proliferate and differentiate
into new osteoblasts8’. Tobacco smoking not only promotes periodontal
diseases but also neoplastic changes at enzymatic level.
Peptidases are enzymes related to neoplasms in oral tissues, cysteine
proteases produced by Porphyromonas gingivalis pathogen is involved
in periodontal diseases”. Cigarette smoking enhances the liver cirrhosis
induced due to alcohol intake10’. Ethanol damages the liver resulting in
hepatic fibrosis and nicotine further promotes liver damage through