Impact of periodontitis definition in epidemiological research. Results from the EPIPAP study in postpartum women.

The purpose of this investigation was to study the impact of using various definitions of periodontitis on the frequency of periodontitis and on the associations with some known risk factors for periodontitis in a population of postpartum women in France. A clinical examination was performed within 2-4 d postpartum in 932 at-term women at five maternity units. We studied six definitions of periodontitis; five were applicable if at least two teeth were found to have the following: (i) a proximal clinical attachment level (CAL) of ≥ 3 mm; (ii) a probing depth (PD) of ≥ 4 mm; (iii) a PD of ≥ 4 mm and a CAL of ≥ 3 mm at the same site; (iv) a proximal PD of ≥ 5 mm or a proximal CAL of ≥ 4 mm; or (v) a PD of ≥ 4 mm and a CAL ≥ 3 mm and bleeding on probing at the same site. The sixth definition required the involvement of four teeth with a PD of ≥ 4 mm and a CAL of ≥ 3 mm at the same site. Associations between case status according to each definition and maternal characteristics (age, educational level, smoking before pregnancy, and time since last dental visit) were analyzed using generalized estimating equation models. The definition of periodontitis had an impact on the frequency of periodontitis, which ranged from 12.1% to 37.7%, and produced different ORs for the associations with risk factors for periodontitis.