Matrix Metalloproteinase‐2 May Be Involved With Increased Bone Loss Associated With Experimental Periodontitis and Smoking: A Study in Rats

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Abstract
Background: Smoking has been associated with periodontitis severity and is considered a risk factor for its development. It has been reported that matrix metalloproteinase (MMP) produced by host cells plays a major role in periodontal tissue destruction. Thus, the present study tested, in rats, the hypothesis that local increased levels of MMP‐2 would be associated with the enhanced periodontitis‐related bone loss after intermittent cigarette smoke inhalation (CSI).Methods: Twenty‐seven adult male Wistar rats were used. A ligature was placed around one of the mandibular first molars of each animal and they were randomly assigned to the following control (N = 13) or CSI (N = 14) group. Sixty days later, the animals were sacrificed, the gingival tissues harvested, and the specimens processed for decalcified sections. Extracts from the gingival tissues were prepared and assayed for MMP‐2 expression.Results: Intergroup comparisons (unligated sites) showed that CSI might directly affect alveolar bone (0.16 ± 0.03 mm2 versus 0.24 ± 0.09 mm2 for non‐smokers and smokers, respectively; P = 0.001). Moreover, CSI significantly enhanced bone loss resulting from experimental periodontitis (0.64 ± 0.36 mm2 versus 1.50 ± 0.50 mm2 for non‐smokers and smokers, respectively; P Conclusion: Within the limits of the present investigation, it can be assumed that the effect of CSI on MMP‐2 levels and activity may account for the increased periodontitis progression rate observed in smokers. J Periodontol 2004;75:995‐1000.