Relationships between alveolar bone levels measured at surgery, estimated by transgingival probing and clinical attachment level measurements.

Alveolar bone level measurements obtained by transgingival probing were compared with alveolar bone levels measured during surgery at 178 sites in 9 patients. Probing depth measurements using constant loads of 30 g and 60 g were also compared with bone levels measured at surgery at the above sites. The effects of inflammation, location of the site on the tooth surface and tooth type were also investigated. Transgingival probing was unaffected by these factors and proved to be an accurate method of measuring alveolar bone levels (r = 0.975). Probing depth measurements were affected by the presence of inflammation, assessed by the bleeding response to probing, and variation in probing load. The effect of inflammation was to reduce the mean distance between the probe tip and the alveolar bone from 2.4 mm to 1.9 mm. None of the relationships between the measurements were significantly affected by the location of the site on the tooth surface, or by tooth type.