Why is pocket depth and bone height not measured in 1mm increments?
The measurement of pocket depth has been shown to only be accurate to within a 2mm range of +1mm to -1mm 90% of the time when done by calibrated and experienced clinicians. While the distance from the cemento enamel junction to crestal bone can be measured on a radiograph, the true condition may not be accurately revealed because a radiograph is a 2 dimensional image of a 3-dimensional entity and the demineralised bone of an active periodontal lesion is below the threshold of radiographic sensitivity. Because of the inaccuracy and variation of clinical measurements for pocket depth and the limitation of radiographic images, evidence of disease progression typically requires a change of 2-3mm. Therefore, diagnostic categorisation and decision making is more consistent and accurate when they are based on a 2mm instead of a 1mm increment, This concept, in part, underpins the pocket depth banding within the BPE examination. Because PreViser does not require measurement in 1mm increments do
