Clinical evaluation of electronic and manual constant force probes.

The objective of this study was to compare the measurements of an electronic controlled-force probe (FP) to that of a manual controlled-force probe (SP) and a conventional probe (CP). Twelve subjects were recruited. A quadrant with no missing teeth (excluding third molars) was selected. Probing depth was measured at 6 sites per tooth (mesiobuccal, buccal, distobuccal, mesiolingual, lingual, and distolingual) by two examiners (AK and KC) each using the three probes in the following sequence: FP, SP, and CP. The same measurements were repeated a week later by both examiners. The mean difference of measurements between CP and FP was 0.375 +/- 0.858 mm (P < 0.05), with 52.7% of the measurements within 0.5 mm and 80% within 1.0 mm. Correlation between measurements was high (0.7208) and significant (P < 0.001). The mean difference between SP and FP was 0.450 +/- 0.863 mm (P < 0.05), with 49.1% of the measurements within 0.5 mm and 76.9% within 1.0 mm. Correlation between measurements was high (0.7354) and significant (P < 0.001). The mean difference between CP and SP was -0.074 +/- 0.373 mm (P < 0.05), with 49.1% of the measurements within 0.5 mm and 76.9% within 1.0 mm. Correlation between measurements was high (0.95) and significant (P < 0.001). Intra-examiner differences varied for each examiner. For both examiners, the correlations for FP (AK = 0.77, KC = 0.46) were lower than that for CP (AK = 0.86, KC = 0.80) and SP (AK = 0.86, KC = 0.83). Inter-examiner comparisons showed that the correlation for FP (0.50) was lower than that for CP (0.85) and SP (0.86). The percentage of sites within 1 mm differences was less for FP (70%) than for CP (94%) or SP (94%). In conclusion, both CP and SP correlated well with FP. None of the three probes investigated completely eliminated probing errors. The CP and SP yielded more reproducible measurements than FP. Regardless of the type of probe used, probing measurements are subject to both intra- and interexaminer errors.