Background: The objective of this investigation is to use noninvasive, stat
e-of-the-art, diagnostic techniques to measure periodontal disease progress
ion and model periodontal disease activity over time. In this investigation
, digital subtraction radiography and an electronic controlled force period
ontal probe capable of attachment level measurement were used to measure bo
ne loss and attachment loss, respectively. The use of these nearly continuo
us measures of attachment and bone loss allowed detection of small amounts
of disease activity and provided data to be used in modeling of the disease
process over time.
Methods: Forty-four patients were studied for 18 months. Examinations used
clinical attachment level measures at 1-month intervals and quantitative ra
diology at 6-month intervals. The sites were analyzed by regression for sta
tistically significant changes. These data were used to determine sites of
periodontal disease activity for testing various models of periodontal dise
ase progression.
Results: Overall 22.8% of sites lost attachment, 5.4% gained, and 71.7% dem
onstrated no statistically significant change. The mean time to lose 1 mm o
f attachment was 8.4 +/- 0.6 months. In the first model tested a step-wise
discriminant analysis was used to determine whether or not baseline measure
ments of plaque (PI), gingival inflammation (GI), attachment loss, and prob
ing depth (PD) could be used to derive a satisfactory model for disease pro
gression. Although the overall model was statistically significant with PI,
PD, and GI contributing to the model (Wilks' lambda = 0.859, F = 5.71, P <
0.0012), its predictive power was relatively weak. A considerably stronger
significant model resulted when the rate of attachment loss over the first
6 months, baseline PI, and baseline GI were included (Wilks' lambda = 0.71
2, F = 14.17, P < 0.00001). A significant model also resulted when bone los
s during the first 6 months and baseline probing depth were included (Wilks
' lambda = 0.438, F = 61.48, P < 0.00001). When the last model was applied
to each site, the sensitivity in predicting disease progression was 80.0% a
nd the specificity in ruling out progressive disease was 93.9%.
Conclusions: This study indicates that clinically significant progression o
f attachment loss in posterior tooth sites occurs as a frequent event in ad
ult periodontitis. The modeling data also suggest that short-term (6 month)
measures of periodontal disease progression greatly improve the ability to
model attachment loss over a longer period in untreated periodontitis pati
ents.