The Periotron 6000 fluid analyser has become widely used as a diagnostic tool for a variety of oral diseases and recent work has questioned its reliability. This paper investigates for the first time, the detailed calibration curves of 2 Periotron 6000 machines across a range of 23 different fluid volumes. Within and between machine reliability is analyzed and the shape of the calibration line determined. The measurement errors incurred by using a single fluid sample, as opposed to mean values of triplicate samples are also determined. We conclude that there are 3 sections to the calibration line, 2 linear and a quadrilateral zone, and that 2 separate regression equations should be used; from 0-0.1 microliter and from 0.1-1.0 microliter. Within machine calibration errors were only 3.2 +/- 7.5%, but values for volumes below 0.2 microliter were as high as 18.7%. Using a single fluid sample rather than mean values of multiple samples, incurred a further 4 +/- 4% error, which was as high as 7% for volumes lower than 0.12 microliter. Whilst significant differences in volume reading existed between different machines (p < 0.0004) and between the same volumes of different fluids (p < 0.00001), individual Periotron calibrations were extremely reproducible and reliable. We conclude that the Periotron 6000 is a reliable and convenient instrument for measuring fluid volumes greater than 0.2 microliter. For volumes lower than 0.2 microliter errors in measurement may be too high for some investigations, but this is likely to be due to problems with evaporation and with measurement technique, rather than errors directly due to the Periotron itself. Finally, for optimum accuracy, the digital display should be re-set to zero after each sample is measured.

The search for markers of periodontal disease activity and progression has accelerated over the last decade, in an effort to replace existing subjective clinical measures of periodontal health status. Research is being aimed at establishing more objective and quantitative methodology, capable of rapid diagnosis prior to the appearance of clinical signs of destructive disease. Such tests need to be sensitive enough to evaluate individual periodontal sites in health as well as disease states. We report the development of a new chemiluminescent assay for the enzyme alkaline phosphatase, that is capable of quantifying the enzyme in sub-microliter volumes of gingival crevicular fluid and serum. The technique will measure alkaline phosphatase (ALP) whilst immobilised on paper strips, without the need for an elution stage. It is simple, versatile and amenable to chair-side use. We discuss in detail the assay procedure and have examined levels of ALP in 11 adult volunteers with clinically healthy periodontal tissues. The mean ALP concentration was 2135 IU/L for GCF and 183 IU/L for serum, a 12-fold difference. There also appeared to be an "oral pattern" of enzyme distribution in healthy periodontal sites, with levels being higher in the anterior region of the mouth and highest in the lower anterior region.

Using a recently developed chemiluminescent assay enabling alkaline phosphatase (ALP) quantification in nanolitre volumes of gingival crevicular fluid (GCF), we have investigated GCF ALP levels in health and in the presence of gingivitis. In gingival health, there was a site-specific pattern of ALP concentration with higher enzyme concentrations around the upper and lower anterior teeth. Furthermore, clinically normal sites that had been subjected to different levels of plaque control produced significantly different ALP levels, (p < 0.03). This indicates that biochemical components of GCF may be used to measure subclinical inflammatory status. The ratio of GCF to serum ALP varied from 6:1 to 11:1, suggesting that a major source of the enzyme is through local production. The main cross-sectional study of 30 patients with gingivitis (276 sites) demonstrated that total GCF ALP levels, collected over a 30-s sampling time were higher for a gingival index of 1 than of 0 (p < 0.014). There was no significant relationship between total GCF ALP and plaque levels of the enzyme, and analysis of plaque within the study group demonstrated very low levels of ALP, indicating that the enzyme is likely to be largely derived from the periodontal tissues. The ratio of GCF ALP levels to those of saliva within individuals was 530:1, thereby eliminating saliva contamination as a risk, when total GCF ALP is being measured.

A case of prepubertal periodontitis in a 6 1/2-year-old boy is described. Following failure to respond to conventional treatment including scaling, oral hygiene instruction and tetracycline therapy, a biopsy was performed and root planing carried out. The biopsy revealed histiocytic infiltration and a diagnosis of Histiocytosis X of the Hand-Schüller-Christian type was made. This case emphasises the role of biopsy in establishing a diagnosis in cases of prepubertal periodontitis that do not respond to conventional therapy.