Introduction: It is well established that periodontal disease (PD) and diabetes mellitus (DM) can have a detrimental effect on each other's disease course, and that cigarette smoking exacerbates both conditions. However, literature on the periodontal status of smokers with DM is scarce, and the studies conducted to date did not use healthy controls or non-smokers with DM as controls. Consequently, the individual effects of smoking and DM on PD are difficult to untangle and estimate.
Methods: A total of 128 participants were recruited to this study and their data analyzed. They were assigned to four groups: smoking patients with DM (SDM); non-smoking patients with DM (NSDM); smokers without DM (control group, SC) and (4) non-smokers without DM (control group, NSC). Each group consisted of 32 age-matched participants. The periodontal status of the participants was assessed by full oral examination. To express periodontal status, we used the four-stage classification introduced by Fernandes and colleagues (J Periodontol. 80(7):1062-1068, 2009). The control of DM was estimated by measuring hemoglobin A1c (HbA1c) levels in the peripheral blood.
Results: A significant difference in the severity of PD was found between the SC and NSC groups (p = 0.027) and between the NSC and SDM groups (p = 0.000), while the difference between the NSDM and SDM groups approached significance (p = 0.052). No person in the smoker groups could be classified as having a healthy periodontal status. The four-stage classification followed a normal distribution in the healthy, non-smoking controls (NSC). Smoking caused a shift toward medium-severe PD, while a marked shift toward the most severe stage was observed when both smoking and DM were present (SDM). There was no significant association between the type of DM and periodontal status, nor between diabetes control and the severity of PD. Persons in the SDM group had significantly fewer teeth than those in the NSC group (mean ± standard deviation: 16.0 ± 7.9 vs. 20.7 ± 5.6; p = 0.02).
Conclusion: Smoking damages the periodontium of even healthy individuals, but the damage is multiplied in a smoker who has DM, even though the effect of DM alone on periodontium health is relatively mild. Our results suggest a synergy between DM and smoking in terms of damage to the periodontal tissues, but the limited sample size of this study does not allow any hard conclusion to be drawn.
Keywords: Comorbidity; Inflammation; Periodontal diseases; Smoking; Type 1 diabetes mellitus; Type 2 diabetes mellitus.