Comparison of periodontal and peri-implant probing by depth-force pattern analysis

The purpose of this study was to compare the tissue resistance to probing and the accuracy of depth determination at different force levels around implants and teeth. In 11 subjects 1 implant and 1 tooth at a comparable location and with comparable probing depth were investigated. The sites were located on either the mesial or distal aspect of the tooth and the implant. A probing device was used which allowed simultaneous monitoring of probing force and probe penetration and which standardized the insertion pathway for repeated measurements. The probing instrument was fitted with an attachment for an aiming device to take a radiograph with the probe tip in the sulcus, using a standardized projection geometry. Probing depth values were determined at 0.25, 0.50, 0.75, 1.00 and 1.25 N probing force. The standard error of the individual measurement (Si), evaluated by comparison of repeated measurements in the same session, was 0.2 mm on implants and 0.1 mm on teeth. For implants there was a trend for slightly better reproducibility at higher force levels. Curve analysis of depth force patterns showed that a change in probing force had more impact on the depth reading in the peri-implant than in the periodontal situation. The mean distance between the probe tip and the peri-implant bone crest amounted to 0.75 +/- 0.60 mm at 0.25 N probing force. It is concluded that peri-implant probing depth measurements are more sensitive to force variation than periodontal pocket probing.