The effects of local anesthetic containing adrenaline on gingival blood flow in smokers and non-smokers

Recent evidence suggests that fundamental differences exist in the development of gingival and periodontal diseases in smokers versus non-smokers. In part, these differences may be attributable to smoking-induced differences in the vascular dynamics of the periodontium. This study monitored gingival blood flow when challenged by a local anesthetic-containing adrenaline in 20 smokers and 20 non-smokers using laser Doppler flowmetry (LDF). The dosage of local anesthetic used (0.5 ml lignocaine hydrochloride 2% with adrenaline 1:80,000) was calculated after establishing a dose-response curve (DRC) for 3 subjects (2 non-smokers and 1 smoker). Plain lignocaine and normal saline were used as controls. The injection of lignocaine-containing adrenaline had little effect on LDF signals when different doses were injected at frequent short intervals, indicating that tolerance to adrenaline had rapidly developed in the receptors of gingival blood vessels. Injection of local anesthetics containing adrenaline consistently resulted in a marked and significant drop (average: 46%, sd;13.5) in the LDF output signals from gingiva; smokers and non-smokers responded similarly. The significant finding of this study was that the recovery of LDF signals to baseline took considerably longer in smokers than in non-smokers. This provides further evidence that gingival blood vessels in smokers with healthy gingival conditions respond differently to those of non-smokers.