Smoking and its effect on the subgingival microflora
Cigarette smoking can reduce the oxidation-reduction potential (Eh), which can cause an increase in anaerobic plaque bacteria. The result from several studies shows that Eh values in gingiva drop significantly after smoking one cigarette. Also, tobacco smoke contains phenols and cyanides which can account for antibacterial and toxic properties which in turn significantly increases the risk of infection.4
Bacterias like P. gingivalis is also more likely to sub gingivally infect smokers than non-smokers. It has been found that three species of Gram-negative bacteria- Branhamella catarrhalis, Neisseria perflava, and Neisseria sicca are more susceptible to cigarette smoke than three species of Gram-positive bacteria Streptococcus mitis, Streptococcus salivarius, and Streptococcus sanguinis.4
Local effects of nicotine in the oral cavity
The oral tissues of smokers are exposed to high nicotine concentrations that negatively affect local cell populations.6
- Smoking impairs revascularization during soft and hard tissue wound healing.
- Nicotine binds to root surface in smokers, and In vitro studies show it can alter fibroblast attachment and integrin expression and decrease collagen production while increasing collagenase production.
- Root surfaces of teeth extracted from smokers show reduced periodontal ligament (PDL) fibroblast attachment as compared to those from non-smokers.
- Cultured gingival keratinocytes and fibroblasts exposed to nicotine produce higher amounts of the proinflammatory cytokines IL-1 and IL-6, respectively.
Impact of smoking on periodontal therapy
Periodontal diseases caused due to smoking have a significant impact on the body’s immune system and wound healing process. This results in the decreased effect of pharmacological therapy and prolongation of the infection.1
- In a study were patients who were smokers underwent scaling and root planning, it was seen that patients showed less improvement compared to non-smokers. 1
- 12 months after undergoing a pocket reduction procedure, patients who are smokers showed a significantly higher percentage of residual pockets. 1
- Smokers showed less probing pocket depth (PPD) reduction in sites with initial PPD ≥5 mm9
- Several studies showed that following non-surgical and surgical therapy, probing depth reduction and clinical attachment level improvement in smokers are 50%–75% higher than those of non-smokers.1
- Patients taking antimicrobials for periodontal diseases there was a greater difference between the control and experimental treatments within smokers as compared to within non-smokers.1
Effects of smoking on the immune system
Smoking causes increased blood leukocytes, neutrophils, lymphocytes, and monocytes, as well as increased hematocrit, haemoglobin, and mean corpuscular volume.7
- Th17 cell is actively involved in worsening smoking-associated inflammation and autoimmune diseases
- Smokeless tobacco extracts affect monocyte and oral keratinocyte production of inflammatory mediators which may play a role in the development of these localized tissue alterations
- Negatively affects phagocytosis, superoxide and hydrogen peroxide generation, integrin expression and protease inhibitor production
- It also decreases salivary IgA and serum IgG