Reports & Studies

Smoking also affects the maintenance phase

A previous article (Smoking & periodontitis ) explained the severe effects of smoking on the periodontium. But how does a smoker’s periodontium behave compared with a non-smoker’s periodontium during the periodontal maintenance phase after active periodontal treatment?

This question was investigated by two Brazilian researchers (Costa & Cota 2019), who compared the results for 142 patients in periodontal maintenance therapy over a period of 6 years with regard to their smoking status. All patients came to periodontal maintenance therapy at least once per year over the 6 years. The smoking status of the patients could be classified as follows:

  • 95 non-smokers
  • 22 former smokers
  • 25 smokers

A ‘periodontal relapse’ was defined as a site with a pocket probing depth of ≥ 4 mm and clinical loss of attachment of ≥ 3 mm in conjunction with bleeding on probing and/or suppuration.

The following results were recorded after 6 years of periodontal maintenance therapy:

  • The incidence of periodontal relapse as a percentage was 44, 68 and 80%among non-smokers, former smokers and non-smokers, respectively
  • Taking into account other relevant risk factors, former smokers and smokers had a 3- and 6-fold higher risk of periodontal relapse than non-smokers.
  • Furthermore, the risk of periodontal relapse among smokers was significantly (2.5-fold) higher than among former smokers.
  • The higher the number of pack years*, the higher the risk of periodontal relapse.
  • The longer ago the former smokers had stopped smoking, the lower their risk of periodontal relapse became.

This study shows very clearly that, following successful periodontal treatment, both smokers and former smokers have a substantially higher risk of relapse and thus of needing further periodontal treatment.

* Tip!
Pack years among smokers are calculated by means of the following formula:
number of cigarettes smoked per day divided by 20 and multiplied by the number of years the patient has been smoking. For example, a smoker who has smoked 30 cigarettes per day for 5 years corresponds to 7.5 pack years (30/20*5).


  1. Costa FO, Cota LOM. Cumulative smoking exposure and cessation associated with the recurrence of periodontitis in periodontal maintenance therapy: A 6-year follow-up. J Periodontol. 2019;90:855–865. 18-0635