Laser Doppler flowmeter measurement of relative gingival and forehead skin blood flow in light and heavy smokers during and after smoking

AIM

To determine the effect of the smoking experience on relative blood flow in gingiva and to compare this to skin.

METHOD

A laser Doppler flowmeter was used to record relative blood flow to healthy gingiva and to forehead skin in smokers and non-smoking controls. Smoking status was verified by quantitative analysis of serum cotinine. Continuous measurements were made over sequential periods with the subject at rest, during a sham smoking exercise, during smoking of a standard research cigarette (2R1, University of Kentucky) for 5 min and throughout a subsequent recovery period. Non-smoking controls sham smoked during the equivalent 5 minute smoking period.

RESULTS

No significant differences with respect to the proportional changes of relative gingival blood flow between time points were observed between the groups. However, between-group comparisons of relative blood flow revealed a significant increase in the relative blood flow to the forehead skin of light smokers (serum cotinine < or =60 ng/ml; n=6), when compared to heavy smokers (serum cotinine > or = 100 ng/ml; n=9) or to non-smokers (serum cotinine < or = 10 ng/ml; n=6), 2 min following the smoking experience (p = 0.007).

CONCLUSION

The results do not seem to support the theory that tobacco smoking causes localised vasoconstriction in the periodontal tissues in humans. These data show that smoking causes an acute increase in relative blood flow in forehead skin in light smokers compared to heavy smokers, suggesting a potential induction of tolerance in regular users of tobacco.

Potential mechanisms of susceptibility to periodontitis in tobacco smokers

Tobacco smoking is probably the most important, controllable environmental risk factor in periodontitis. It results in changes in the vascular, inflammatory, immune and healing responses. The degree of exposure to tobacco smoking can be measured in pack years or by measuring serum cotinine and nicotine levels. In a previous paper we reported elevated levels of serum soluble intercellular adhesion molecule-1 (sICAM-1) in smokers, regardless of periodontal status. Elevated sICAM-1 has been found to be a risk marker for cardiovascular disease. In the present paper we report the short-term effects of an episode of smoking on blood flow and levels of sICAM-1. Human volunteers included non-smokers, light smokers and heavy smokers. Relative blood flow was monitored in the gingivae and forehead skin using a laser Doppler flowmeter and serum levels of sICAM-1, cotinine and nicotine measured before during and up to 60 min following an episode of smoking. We could not provide evidence to support the theory that there is localized vasoconstriction within the gingival tissues. In contrast, there was a significant increase in blood flow in the forehead skin of light smokers which was not observed in non-smoking controls or in heavy smokers, suggesting a long-term tolerance in this latter group. The level of sICAM-1 remained unchanged during this episode, further suggesting a long-term effect. In a parallel group of subjects, we were able to demonstrate a direct significant correlation between sICAM and serum cotinine levels. These observations may be relevant to aetiological mechanisms in periodontitis and other smoking-associated diseases.