Introduction 

Did you know in 2022, approximately 6.4 million people aged 18+ in the UK smoked tobacco? 

Definition of tooth decay 

Tooth decay occurs when bacteria damage the hardened outer surface of teeth (enamel) creating cavities (dental caries), causing bacterial infection leading to dental abscesses, gum/periodontal disease (periodontitis) and tooth loss.¹

Study purposes

The purposes of this article are:

• Investigating tobacco use consequences on oral health
• Exploring signs/symptoms and mitigation strategies of tobacco-induced tooth decay
• Using study-based evidence to link tobacco use with tooth decay

Tobacco-induced effects on oral health

Tobacco constitution and its effect on oral tissues

Tobacco smoke contains 7000+ chemicals.³ The main components of tobacco smoke include:

Nicotine

Nicotine constricts gum blood vessels causing less blood flow and thus less oxygen to heal inflamed gums in periodontitis.² This causes:

• Loss of gum adhesion to teeth
• Increased inflamed gum pocket depth
• Alveolar bone loss which prevents teeth from being aligned and immovable whilst biting and chewing

The consequences are roots of teeth being exposed allowing bacteria entry to cause tooth decay.²

Carcinogens 

• Polycyclic aromatic hydrocarbons (PAHs)
• Nitrosamines

PAHs and nitrosamines cause mutations in DNA promoting oral cancer development and interrupting the adaptive immune response to inflammation.^3,17

Toxins

• Benzene
• Formaldehyde 
• Carbon monoxide gas

Free radicals produced by the degradation of toxins in the body cause oxidative stress, thus cell damage and death collectively causing tissue inflammation. Carbon monoxide creates an oxygen-depleted environment where less oxygen carried in blood is supplied to oral tissues leading to poor wound healing in gum disease and bacterial growth therefore leading to plaque, tartar and tooth decay progression.³

Irritants

• Tar - Tar causes darkening of teeth, bad breath (halitosis) and compromises immune system function leading to increased inflammation and decreased wound healing time in oral diseases³

Mechanisms of tobacco-related tooth decay

Tobacco product use (cigarettes and chewing tobacco) causes tooth decay. The tobacco-induced tooth decay process involves:

• Creating an oxygen-deficient environment (hypoxia) in body tissues, slowing oxygen delivery to oral mucosal tissues which slows the healing of inflamed gums in gum disease⁴
• Creating acidic pH conditions where pathogenic bacteria can grow and proliferate⁵
• Reducing salivary flow causing dry mouth (xerostomia), resulting in reduced pH neutralisation of acids produced from fermenting bacteria when consuming acidic and sugary, carbohydrate-rich products⁵
• Reduced saliva flow decreases antibacterial, enamel remineralising, rinsing and peri oral tissue repair functions of saliva causing plaque formation and dental caries⁵ 

Chewing tobacco and e-cigarettes

Chewing tobacco which contains sugar, causes a drop in salivary pH (similar to cigarettes) and has prolonged contact with teeth which collectively increases dental caries incidence.^6,7

E-cigarettes have been used as a replacement for cigarettes.⁸ A study reported those using e-cigarettes were likely to report a tooth removal due to periodontitis or caries more (56%) than those who did not (51%).⁸ 

Effects of tobacco use on oral health

Tooth anatomy

The tooth anatomy consists of:

• The enamel 
• The dentin layer underneath the enamel
• The pulp underneath the dentin which contains the blood supply and nerves 
• The tooth root which secures the tooth firmly in position¹

The periodontium (composed of gums, alveolar bone, periodontal ligament and cementum) reinforces beneath and around the teeth, which means it will not move whilst biting or chewing.⁹ 

Tooth decay and periodontitis formation

Tooth decay occurs when plaque (an adhesive film formed by bacteria) causes cavity development in the enamel by removing minerals.¹ Cavities develop due to:¹

• Harmful bacteria ferment sugars, releasing acids to damage the enamel
• An acidic, oxygen-depleted oral cavity promotes the increase of harmful bacteria which require no oxygen for growth and proliferation

The sequence of tooth decay involves:

• The dissolving of the enamel layer
• Cavity formation in the enamel layer
• Dentin decay
• Pulp decay, which causes tooth pain
• Tooth abscess formation, which leads to tooth loss

Gum inflammation (gingivitis) can progress to periodontitis in which gums recede, bleed, and are sore and red. The immune response will act to clear gum inflammation but will cause damage to the periodontium causing tooth loss.⁹

Research evidence

Studies linking tobacco use with increased tooth decay

A study which had a sample of over 200 patients, compared the effects of using smokeless tobacco vs smoking and found:

• Both correlated with an increased decayed, missing and filled teeth index (sum of patient caries, filled and missing teeth) and connected alveolar bone tissue destruction
• Association of smokeless tobacco use with gum recession, particularly in the area of the mouth where the smokeless tobacco is being chewed¹⁰
• Higher numbers of missing teeth were found in smokeless tobacco users¹¹

A longitudinal study which looked at patients undertaking periodontal therapy over 12 years found smokers developed significantly more active and non-active dental root caries than non-smokers.^12,13 This study also found pathogenic salivary lactobacillus bacteria median counts, which cause dental caries, to be significantly varying between smokers (higher) and non-smokers (lower).^12,13

Epidemiological studies on tobacco-related oral health issues

A 3-year study involving 22,009 patients found 36.6% had tooth decay with smoking as a risk indicator, and that smoking cessation can result in a 7% decrease in dental caries development. This study also found that smoking was a risk indicator for periodontal disease and peri-implant pathology; the prevalence of periodontitis was 17.6% and of peri-implant pathology was 13.9% out of 22,009 patients.¹⁴

Clinical manifestations

Signs and symptoms of tobacco-induced tooth decay

• Tooth sensitivity to hot and cold temperatures, liquids, touch 
• Throbbing, mild, aching to severe, sharp tooth pain 
• Black, brown or white staining on teeth
• Bad breath
• Unpleasant mouth taste
• Bleeding and receding gums¹

Diagnosis 

A dental examination can diagnose tooth decay and periodontitis. The diagnosis involves:^15,18

• Checking for brown, black or white teeth staining. Active dental caries are white and have a stickier and softer tooth surface with bleeding gums upon probing 
• Checking teeth hardness and if plaque is present by checking teeth texture (either visibly glossy or matte) 
• Using light and X-rays for teeth to visualise cavities 
• Using a probe in between gums and teeth to check for gum bleeding 

Treatment 

A dentist may prescribe higher concentrations of fluoride toothpaste, will suggest flossing and brushing your teeth twice a day correctly, and may apply topical fluoride to your teeth in the form of varnishes, gels and sprays.¹⁵

If dental decay is irreversible, tooth extraction and periodontal bone surgery are options.^1,9 If cavities are large, crowns may be utilised alongside dental implants.

Prevention and management 

Oral health routine reducing tobacco-induced tooth decay

• Floss and brush teeth twice every day to remove plaque and food debris¹⁵
• Smoking/smokeless tobacco cessation– nicotine replacement and behavioural therapies and use quit smoking telephone chat lines¹⁶ 
• Regular dental examination every 6 months 

Future studies

Future research could involve:

• Exploring the association of e-cigarette use with tooth decay and other oral health diseases
• Comparative studies of e-cigarettes, smokeless and smoking tobacco use on tooth decay and a follow-up study after cessation
• Understanding mechanisms by which tobacco components cause tooth decay

New technologies utilised in the diagnosis of oral diseases

Limitations of X-rays in the diagnosis of tooth decay are:¹⁸

• Cannot diagnose early stages of dental caries development 
• Cannot track the progress of caries development to prevent it 

New technologies may provide solutions to these limitations and include:

• Laser fluorescence technology can quantify bacterial products in dental caries and could visualise early caries development¹⁸
• Digital Imaging Fiber-Optic Transillumination produces an image using fibre-optic to visualise tooth demineralisation, fissures, or crevices and can quantify caries development¹⁸

However, new technologies cannot deduce whether dental caries are active or not. 

FAQs

What are the effects of tobacco chewing on the oral cavity?

Chewing tobacco causes dental caries, gum disease with resulting tooth loss, and mouth and throat-related cancers.

How does tobacco cause tooth decay?

Tobacco use causes dry mouth which promotes bacterial growth to form plaque and tartar, resulting in tooth decay.^6,7 Tobacco components compromise immune system function which means it cannot fight bacterial infection and its resultant inflammation which causes dental caries, periodontal disease and tooth loss.³

Summary

The impacts of tobacco use on oral health are various. Smoking and chewing tobacco contains nicotine, a highly addictive stimulant, carcinogens, toxins and irritants which contribute to dental caries, gum disease accompanied by bacterial infection and often resulting in dental abscesses and eventually tooth loss. 

Tobacco-induced reduced saliva production and constriction of blood vessels promote bacterial growth in tooth decay. This also affects wound healing properties and leads to periodontal disease. Management strategies include frequent dental examinations, quitting smoking and maintaining good oral hygiene practices.