Comparing clinical attachment level and pocket depth for predicting periodontal disease progression in healthy sites of patients with chronic periodontitis using multi-state Markov models

Abstract

Aim: To understand degeneration of healthy sites and identify factors associated with disease progression in patients with chronic periodontitis.

Material and methods: Data on healthy sites from 163 American and Swedish subjects were analysed using two-three-state (health, gingivitis, chronic periodontitis) Markov models based on bleeding on probing (BOP), and either clinical attachment level (CAL) + BOP or pocket depth (PD) + BOP.

Results: In 2 years, 10% (CAL + BOP) and 3% (PD + BOP) of healthy sites developed chronic periodontitis. On average, healthy sites remained healthy for 32 months before transiting in both models. Most transitions (87-97%) from health were to the gingivitis state. The expected duration of the gingivitis lesion was 4-5 months and sites recovered with a high probability (96-98%). Disease severity as measured by number of sites with CAL/PD > 4 mm at baseline and smoking, were associated with fast progression from health to chronic periodontitis within 6 months as were gingival redness in the PD + BOP model only. With age, the rate of disease progression to gingivitis decreased.

Conclusion: Transition probabilities for gingivitis and chronic periodontitis were higher with CAL + BOP than with PD + BOP. Smoking and disease severity were significant predictors for fast progression.

Keywords: antibiotics; chronic periodontitis; multi-state Markov models; periodontal therapy.

Figure 1

A general multi-state Markov model for gingivitis and chronic periodontitis onset based on CAL + BOP (left panel) and PD + BOP (right panel) classifications. States 1, 2 and 3 correspond to health, gingivitis and chronic periodontitis and possible transitions are represented by arrows. Sites can advance from a healthy state to a gingivitis state, and optionally recover from gingivitis to healthy. Because data were observed at arbitrary time points, direct transitions from health to chronic periodontitis are also permissible. However, sites that advance to chronic periodontitis (absorption state) are not expected to recover (transit to healthy state) or transit to gingivitis state. Q is the transition intensity matrix. For example, q₁₂ represents the instantaneous risk of moving from state 1 to state 2. Because transitions 3 → 1 and 3 → 2 are not permissible, q₃₁ = q₃₂ = q₃₃ = 0. BOP, bleeding on probing; CAL, clinical attachment level; PD, pocket depth.

Figure 2

A plot of predicted transition probabilities for sites that were healthy at 6 months based on CAL + BOP classification. Here, states 1, 2 and 3 correspond to healthy, gingivitis and chronic periodontitis. Transition probabilities (1 → 3) were higher than for PD + BOP (see Fig.3). BOP, bleeding on probing; CAL, clinical attachment level; PD, pocket depth.

Figure 3

A plot of predicted transition probabilities for sites that were healthy at 6 months based on PD + BOP classification. Here, states 1, 2 and 3 correspond to health, gingivitis and chronic periodontitis. Estimates for transition probabilities (1 → 3) were lower than for CAL + BOP (see Fig.2). BOP, bleeding on probing; CAL, clinical attachment level; PD, pocket depth.