Prediction and diagnosis of attachment loss by enhanced chemiluminescent assay of crevicular fluid alkaline phosphatase levels.

The current study aimed to apply a novel enhanced chemiluminescence assay in the analysis of gingival crevicular fluid (GCF) alkaline phosphatase (ALP) levels from patients with untreated adult periodontitis. 3666 sites in 25 patients were monitored prior to and after attachment loss was detected with a Florida disc probe. Parameters assessed were, relative attachment level, probing pocket depth, occurrence of bleeding on probing (single episode), GCF volume (microliter), total ALP levels (microIU/30 s sample time) and ALP concentration (IU/l). After recruiting patients to the study, all measures were taken at baseline and 3 months later, prior to the institution of non-surgical periodontal therapy at active sites. Thresholds for determining attachment loss were calculated using a modification of the tolerance method. The mesio-buccal sites of all teeth had GCF samples collected. The size of individual patient thresholds used to define whether attachment loss had occurred, was dependent upon the discomfort felt by that patient during electronic probing, with a positive correlation existing between discomfort on probing (10 cm visual analogue scale) and threshold size (R = 0.52, p < 0.049). A total of 274 sites (7.5%) experienced attachment loss of which 39 sites had GCF samples available for analysis. Total ALP levels were significantly higher at baseline for sites that progressed to attachment loss than paired controls (p < 0.003), but all other parameters showed no differences (p > 0.1). There were significant increases in total ALP levels and GCF volumes for active sites between baseline and 3 month measures (p < 0.01), but not for control sites or test site ALP concentration (p > 0.8). The diagnostic accuracy for GCF ALP as a predictor of future attachment loss (threshold 900 microIU/30 s) was 64%, with +ve and -ve predictive values of 62% and 68%. When a threshold of 1300 microIU/30 s was selected for ALP as a marker of recent or currently active disease, diagnostic accuracy and +ve/-ve predictive values were 77% and 77%/76%, respectively. These results indicate that total GCF ALP levels may serve as a predictor of future or current disease activity.