Harmful Effects on the Ears

IgG฀antibody฀levels,฀indicative฀of฀an฀immunosuppressive฀effect฀ [205] .฀In฀addition,฀nicotine฀has฀ been฀reported฀to฀inhibit฀the฀proliferation฀of฀osteoblasts฀in฀vitro฀ [206] ฀and฀to฀reduce฀the฀gingival฀ circulation฀ [207] ,฀although฀these฀indings฀need฀to฀be฀conirmed฀in฀further฀investigations. Increased฀plaque฀formation฀is฀a฀proven฀inding฀among฀smokers฀ [208] ,฀and฀this฀leads฀to฀ increased฀bacterial฀colonisation฀of฀the฀oral฀cavity฀and฀gingival฀region฀ [209] ฀with฀all฀the฀ attendant฀consequences.฀Furthermore,฀melanosis฀of฀the฀tongue฀black฀hairy฀tongue฀and฀of฀ the฀ oral฀ mucosa฀ may฀ result฀ from฀ the฀ pigmentation฀ of฀ basal฀ keratinocytes฀ [210] .฀ These฀ changes฀are฀reversible฀on฀smoking฀cessation.฀As฀a฀result฀of฀the฀thermal฀insult฀of฀smoke,฀ pipe฀ smokers฀ often฀ display฀ stomatitis฀ or฀ smoker’s฀ palate฀ [211] ,฀ a฀ condition฀ that฀ may฀ undergo฀transformation฀to฀a฀precancerous฀lesion฀in฀rare฀cases. With฀a฀consumption฀of฀20฀cigarsday฀for฀13฀years,฀Sigmund฀Freud฀may฀serve฀as฀a฀typi- cal฀example:฀he฀developed฀leukoplakia฀with฀recurring฀oral฀cancers,฀for฀which฀he฀had฀to฀ undergo฀surgery฀on฀numerous฀occasions.฀Despite฀having฀to฀wear฀a฀prosthetic฀plate฀in฀his฀ upper฀and฀lower฀jaw,฀he฀continued฀to฀smoke฀persistently฀until฀his฀death. Smoking฀encourages฀discolouration฀of฀the฀teeth฀and฀abrasion฀especially฀in฀pipe฀smok- ers฀or฀users฀of฀chewing฀tobacco.฀In฀association฀with฀tooth฀loss,฀these฀changes฀ultimately฀ lead฀to฀occlusive฀disturbances฀ [211] .฀Such฀indings฀are฀encountered฀more฀frequently฀in฀the฀ USA฀ than฀ in฀ Europe,฀ particularly฀ since฀ 10–16฀ million฀ US฀ Americans฀ use฀ smokeless฀ tobacco฀as฀an฀alternative฀to฀smoking฀cigarettes฀ [212] . Compared฀with฀non-exposed฀children,฀children฀passively฀exposed฀to฀maternal฀smoking฀ are฀found฀to฀be฀at฀increased฀risk฀for฀the฀development฀of฀caries฀OR฀=฀1.54฀vs.฀1.06;฀p฀฀0.05฀ [213] .

7.3.3 Oral and Laryngeal Cancer

More฀than฀9฀out฀of฀10฀oral฀cavity฀cancers฀in฀men฀and฀6฀out฀of฀10฀in฀women฀are฀caused฀by฀ smoking,฀while฀alcohol฀has฀been฀identiied฀as฀the฀strongest฀additional฀risk฀factor฀ [214] .฀ Compared฀ with฀ non-smokers,฀ the฀ relative฀ risk฀ in฀ smokers฀ is฀ increased฀ by฀ 2-฀ to฀ 18-fold฀ [215] ,฀the฀increase฀being฀dependent฀on฀the฀number฀of฀cigarettes฀smoked฀daily฀ [216] .฀The฀ risk฀of฀cancer฀development฀declines฀just฀a฀few฀years฀after฀smoking฀cessation฀ [217] ,฀in฀one฀ study฀by฀50฀after฀3–5฀years฀of฀smoking฀abstinence฀ [216] .฀The฀eficacy฀of฀radiation฀therapy฀ in฀such฀tumours฀is฀considerably฀reduced฀where฀patients฀continue฀to฀smoke฀ [218] .฀Likewise,฀ 8฀out฀of฀10฀cases฀of฀laryngeal฀cancer฀are฀caused฀by฀cigarette฀smoking฀ [219] ,฀and฀the฀causal฀ relationship฀has฀been฀conirmed฀by฀numerous฀epidemiological฀and฀clinical฀studies฀ [220] .฀ The฀risk฀of฀laryngeal฀cancer฀is฀also฀associated฀with฀the฀number฀of฀cigarettes฀smoked฀ [220] .฀ For฀every฀incremental฀increase฀in฀pack-years฀of฀smoking,฀there฀is฀a฀small฀but฀measurable฀ increase฀in฀the฀odds฀that฀a฀patient’s฀laryngeal฀cancer฀will฀already฀be฀stage฀III฀or฀IV฀at฀initial฀ diagnosis฀ [221] .฀The฀bidi฀cigarettes฀commonly฀smoked฀in฀India฀constitute฀a฀particular฀dan- ger:฀ compared฀ with฀ non-smokers,฀ smokers฀ of฀ 20฀ bidi฀ cigarettesday฀ have฀ a฀ 12.68-fold฀ higher฀relative฀risk฀for฀laryngeal฀cancer฀ [222] . It฀has฀been฀suggested฀that฀the฀mechanisms฀underlying฀carcinogenesis฀are฀mediated฀by฀ acetaldehyde฀formed฀by฀alcohol฀and฀cigarette฀smoke,฀a฀process฀that฀is฀also฀encouraged฀by฀ microbial฀oxidation฀of฀ethanol฀by฀the฀oral฀microlora฀ [223] .฀The฀implications฀are฀especially฀