On the symmetry of periodontal disease

Background, aim: Symmetry is a common feature of biological systems, and ca n be observed in multiple aspects of the human body. The purpose of this st udy was to estimate the impact of symmetry on variance observed in intraora l topographic distribution patterns of chronic periodontitis. Method: This analysis was performed on a data set from 56 subjects, includi ng clinical and microbiological variables, recorded at the mesial and dista l aspect of every tooth in the entire dentition. The impact of contralatera l conditions was determined on the level of the site, the tooth, and the qu adrant. Results: Significant correlations were detected between probing depths, rec ession, attachment levels, total cultivable bacterial counts and the plaque index recorded on the right and left side on all levels of analysis. The o dds for bleeding on sampling, as well as for the presence of P. intermedial nigrescens and A. actinomycetemcomitans increased significantly if the resp ective contralateral site was positive for the same parameter. In combining ipsilateral and contralateral parameters into the analysis it could be sho wn in several instances that this contralateral effect was stronger than th e impact of other, ipsilateral factors. As an example, the odds for bleedin g on sampling increased up to 10 fold if the contralateral site was bleedin g, whereas the ipsilateral total cultivable count, determined at the same s ite, explained less than 30% of the variation in the bleeding tendency. Conclusion: These findings support the view that the development of periodo ntal disease in any site cannot be explained by the influence of local detr imental factors alone.