Because the mouth is a gateway to the body, smoking is the worst enemy for teeth and particularly for gums, and its harmful effects are major. Smoking addiction directly contributes to the development of periodontal diseases including gingivitis and periodontitis and causes very unpleasant problems in smokers' mouths. 

HALITOSIS 

Smoking itself causes a specific smell on top of that produced by other substances that are added to cigarettes, such as tar and many other additives. All of this creates a peculiar breath odour and/or exacerbates already-existing halitosis that is caused by other factors. Smoking also makes bad breath stronger by increasing dryness and irritation to oral mucosa and to upper respiratory and digestive tracts. This contributes to a lack of oxygen and makes it difficult to carry out oral hygiene, which must be supplemented with specific anti-halitosis products along with physical methods such as the use of tongue scrapers and, of course, quitting the habit. 

TEETH WITH AN UNATTRACTIVE COLOUR 

The change in the colour of teeth, generally to a yellowish tone, is the most obvious and unsightly sign of smoking, reflecting the poor oral condition that this condition can cause. 

REDUCED SENSE OF TASTE AND SMELL 

This is a very unpleasant and possibly dangerous result. Smoking affects its users by progressively reducing their ability to taste and smell, particularly savoury foods, so that their blood pressure may even increase, as they may be unaware of their excessive salt intake. 

DISEASED GUMS ARE LESS OBVIOUS 

Because smoking reduces gingival blood flow, gums may be more pale and appear less inflamed than they really are. Therefore, periodontal disease in smokers is in a way hidden, as one of the main warning signs that lead many people to consult their dentist or periodontist is less frequent and clear: gingival bleeding. Smokers must be made aware of this characteristic and visit their dentist regularly, even if they think their gums are ok. 

GINGIVAL DEFENSE MECHANISMS ARE CONSIDERABLY ALTERED 

A cigarette contains some 4,000 components that are pharmacologically toxic, mutagenic and of which approximately 400 are carcinogenic. One of the consequences is that smokers have clearly reduced gingival defenses against the bacterial attack of dental plaque (biofilm), which substantially increases an individual's susceptibility to periodontal infection. 

PERIODONTITIS MORE COMMON AND MORE SEVERE 

Besides the fact that smokers are at a three times greater risk of having periodontitis and that periodontitis progresses more quickly in these individuals than in non-smokers, diagnosis in smokers tends to be delayed by masked signs, such as bleeding, and in turn, the start of the most appropriate treatment for this disease is also delayed. 

INFERIOR RESPONSE TO BASIC PERIODONTAL TREATMENT 

Following initial treatment for periodontitis, which includes monitoring patient's oral hygiene and removal of bacteria, calculus, etc. by means of techniques such as scaling and root planing, a great number of serious research studies indicate that treatment response is worse in smokers than in non-smokers. 90% of periodontitis cases that do not adequately respond to conventional periodontal disease therapy involve smokers. 

PERIODONTAL SURGERY IS LESS EFFECTIVE 

In advanced cases of periodontitis, when periodontal surgery is needed, results are less favourable in smokers than in patients who do not smoke. Similarly, when an exposed tooth root is intended to be covered using gum graft surgery, the results are much less predictable when patients are smokers. The same occurs when bone regeneration techniques are applied locally to the areas surrounding teeth that were lost due to disease, either using bone grafts, special membranes, etc. 

GREATER PERIODONTITIS RECURRENCE RATE 

Periodontal disease can be chronically controlled in most cases, but smoking is one of the main factors that hinders this control so that periodontitis does not stabilise or reappears despite the standard control measures taken. Furthermore, and this is very important, smokers are at greater risk for losing their teeth during the periodontal maintenance phase, a phase that is essential for maintaining healthy teeth for the rest of your life. 

DENTAL IMPLANT FAILURE RATE IS MUCH HIGHER 

People who smoke have at least twice the failure rate of dental implants than non-smokers. Therefore, smoking is considered a predisposing factor for implant failure and is an essential risk factor in the aetiology of peri-implantitis (infected implant). 

GREATER DELAY IN WOUND HEALING 

Lowered defences and gingival blood flow in smokers not only increases the risk for infection, but also significantly reduces the repair capacity of tissues, substantially delaying healing of both traumatic injuries and surgical wounds, as previously mentioned. 

GREATER RISK FOR ORAL CANCER 

Tobacco cigarettes are highly irritant and contain a large number of cancer-causing substances, particularly nicotine and tar. The addition of alcohol to smoking, which is very common, considerably increases the risk for oral cancer, the most alarming oral disease, both because of its high mortality as well as its severe and aesthetic consequences.