Lead exposure and periodontitis: A cross-sectional evaluation

The evidence that lead may adversely affect bone metabolism and depress the immune system makes lead a potential risk factor for periodontitis. The objective of this study was to test the hypothesis of association between lead blood levels (PbB) and periodontitis. This study included individuals from 20 to 55 years old (n = 8801) from the Third National Health and Nutrition Examination Survey (1989–1994). The proposed objective was investigated through the analysis of the association between PbB with the average attachment loss (AVLOSS), with the extent and severity of periodontitis as well as with the extent of bleeding on probing (BOP). These associations were investigated adjusting for the major confounders using multiple linear regression analysis, multinomial logit model or logistic regression as appropriate. Statistically significant correlation between PbB and AVLOSS was only observed among individuals with established periodontitis (AVLOSS ≥ 1.5mm). The ORs comparing individuals with extensive periodontitis (≥20% of sites with ≥4mm of attachment loss) with those without periodontitis for moderate (3–7μg/dL) and high lead exposure (>7μg/dL) were respectively 1.72 (95%CI: 1.02–2.91) and 2.57 (95%CI: 1.32–5.01). Similar findings were obtained for the analysis of severity of periodontitis (defined as individuals with ≥1.5 mm of AVLOSS). The association between PbB and BOP was only observed among males. Only the OR for the effect of high levels of lead comparing extensive BOP with moderate and no bleeding on probing was significant 1.60 (95%CI: 1.10–1.32). However, the test for trend was statistically significant for both males and females. Although this study shows significant associations, the interpretation of the findings should be made carefully: (1) this is a cross-sectional study, therefore, causality cannot be inferred; (2) PbB is strongly associated with socioeconomic factors (SES) and this association might have increased with the decline of lead exposure in the US, making PbB a good marker for individuals with sustained low SES and living in poor neighborhoods. Therefore, this study showed statistically significant positive association between PbB with periodontitis and gingivitis. However, further studies are necessary to confirm our results and to elucidate the role of SES related factors in this association.