Background: Information is lacking on the natural history of periodontitis through the third and fourth decades of life.
Methods: Periodontal examinations were conducted at 26 and 32 years of age in a longstanding prospective study of a birth cohort born in Dunedin, New Zealand, in 1972 and 1973. At each age, gingival recession (GR) and probing depth (PD) were recorded at three sites per tooth using a diagonal half-mouth design (measurements were made in all four quadrants at 32 years of age, but longitudinal comparisons were made using only the half-mouth data).
Results: A total of 882 individuals were examined at both ages. The mean number of measured sites fell between 26 and 32 years of age. The overall prevalence of one or more sites with >or=4 mm combined attachment loss (CAL) rose from 18.6% to 21.8%, whereas there were greater increases in the proportion with two or more sites with >or=4 mm CAL (from 8.0% to 12.6%) and one or more sites with >or=5 mm CAL (from 3.6% to 8.0%). The extent and severity of CAL also increased. A total of 403 individuals (45.7%) had an increase in CAL >or=2 mm at one or more sites, whereas 110 (12.5%) had a CAL increase >or=3 mm at one or more sites. Seen in approximately 4% of sites, negative GR (i.e., gingival enlargement) had a substantial effect on PD-based estimates. An increase in PD >or=2 mm at one or more sites was experienced by 345 individuals (39.1%), whereas 88 people (10.0%) had an increase in PD >or=3 mm at one or more sites. The greatest mean attachment loss was experienced at disto-lingual sites on molars, and most manifested as PD increases. Notable increases in GR were seen with lower incisors and canines.
Conclusions: Periodontal loss of attachment continues among a sizable proportion of people from the third to the fourth decade of life; however, contrary to patterns in older adults, changes in the PD component are greater than the changes in the recession component. Incident attachment loss is most frequently observed at proximal sites on posterior teeth.