The aim of this paper was to evaluate cigarette smoking and a history of treated periodontitis, both alone and combined, as risk factors for adverse implant outcomes.

Considerable heterogeneity among studies was found, making comparisons of outcomes difficult. The definitions of periodontitis and non-periodontitis patients differed among studies. Where a description of the type of periodontitis was given, the type of periodontal disease was usually described as chronic periodontitis.

While all studies reported that periodontal patients were treated, and the majority of studies reported regular supportive periodontal therapy, the periodontal status was infrequently reported.

A range of definitions for smokers, nonsmokers, and former smokers were used in the studies. Few studies reported and adjusted for confounding factors.

The outcomes addressed in this review were implant survival, implant success (as defined by the authors), longitudinal radiographic bone levels, and occurrence of peri-implantitis.

• History of Treated PeriodontitisThree controlled studies reported statistically significantly lower implant survival rates in patients with a history of periodontitis compared to non-periodontal patients. However, the majority of studies report high implant survival rates (> 90%). There is evidence that patients with a history of periodontitis are at greater risk for peri-implantitis than patients without a history of periodontitis (reported odds ratios ranged from 3.1 to 4.7).
• SmokingThere is strong evidence that smoking is a risk factor for adverse implant outcomes. The evidence shows that smokers have an increased risk of peri-implantitis (reported odds ratios ranged from 3.6 to 4.6) and radiographic marginal bone loss (reported odds ratios ranged from 2.2 to 10) compared to nonsmokers. There is some evidence for a dose effect of cigarette smoking.
• History of Treated Periodontitis and Smoking CombinedThere are few studies evaluating the combined effect of smoking and a history of periodontitis. There is some evidence of an increased risk for implant failure and bone loss in smokers with a history of treated periodontitis compared to nonsmokers with a history of treated periodontitis.

With respect to a history of treated periodontitis and smoking, the following recommendations can be made:

• History of Treated PeriodontitisA history of treated periodontitis is not a contraindication for implant placement. However, patients with a history of treated periodontitis should be informed of an increased risk of implant failure and peri-implantitis. Patients with a history of periodontitis should receive individualized periodontal maintenance and regular monitoring of peri-implant tissue conditions.
• SmokingSmoking is not a contraindication for implant placement. However, patients should be informed that the survival and success rates are lower in smokers. Heavy smokers should be informed that they are at greater risk of implant failure and loss of marginal bone. Patients who smoke should be informed that there is an increased risk of implant failure when sinus augmentation procedures are used.
• History of Treated Periodontitis and Smoking CombinedPatients who smoke and have a history of treated periodontitis should be informed that they have an increased risk of implant failure and peri-implant bone loss.