TOBACCOANDSMOKING:ENVIRONMENTAL FACTORS THATMODIFYTHEHOSTRESPONSE(IMMUNESYSTEM) AND HAVEAN IMPACTON PERIODONTAL HEALTH

Thisreview summarizes thecurrent dataontheeffects ofsmoking andtobacco ontheimmunesystem andits potential impact onperiodontal health. Smokers are2.5-6 times morelikely todevelop periodontal disease thannon-smo- kers, andthere isevidence foradirect correlation between thenumberofcigarettes smokedandtherisk ofdeveloping dis- ease. Tobacco users also tendtoexhibit increased severity ofperiodontal disease. Direct correlations between tobacco useand increased attachment loss andpocket depth andreduced bonecrest height havebeenreported. Although thecorrelation between tobacco useandperiodontal disease isquite strong, therole oftobacco inthepatho- genesis ofperiodontal disease isuncertain. Recent studies indicate that onepotential mechanism isthat tobacco useexacer- bates periodontal disease because italters theimmuneresponse toperiodontal pathogens. Indeed, smokers exhibit increased numbers ofperipheral bloodmononuclear phagocytes whichappear tobefunctionally compromised. Inadequate phagocyte activity could reduce theclearance ofpathogens fromtheoral cavity andthereby facilitate thedevelopment ofperiodontal dis- easeTobacco-exposed B-andT-lymphocytes exhibit reduced proliferative capacities which could limit theproduction ofpro- tective immunoglobulins against oral pathogens. Therisk factors forperiodontal disease canbebroadly classified asgenetic, environmental, host-response factors, and host-related factors suchasage. Tobacco, anenvironmental factor, undermines thehostresponse andmayfacilitate thedevel- opmentandprogression ofperiodontal disease. Thisreview highlights theinter-relatedness oftwooftherisk factors associ- atedwithperiodontal disease.