Attachment level measurements with a constant force electronic probe.

The purpose of the present investigation was to evaluate the reproducibility of probing attachment level measurements using a newly developed constant force electronic probe. The probing force was preset at 25 g (probe diameter 0.4 mm) and was connected to a computer through a variable differential transformer. The measurements were performed on 10 patients with minimal signs of periodontal disease, using individually made acrylic stents. When the probe was in place and a foot switch depressed, the measurement was stored on the computer to the nearest 0.1 mm. The measurements were performed by one periodontist and one hygienist during one visit, and were then repeated by the same periodontist and another hygienist during a second visit. The results showed high correlations between the periodontist and the hygienist during one visit, between the two visits for the periodontist, and between the two hygienists at two different visits. The subject threshold for attachment loss was calculated according to Haffajee and co-workers, and was found to average 0.84 mm for the measurements performed by the periodontist and the hygienist during the same visit. For the periodontist during two separate visits and for the two different hygienists, the average threshold was 0.99 and 1.02 mm, respectively. Duplicate measurements were also performed by one periodontist at one visit on 10 patients with advanced periodontal disease. The average subject threshold for these patients was 0.60 mm. It may be concluded that with the constant force electronic probe, loss of attachment can be detected earlier than when conventional instruments are used.