THE REPRODUCIBILITY AND VALIDITY OF FURCATION MEASUREMENTS USING A PRESSURE-CALIBRATED PROBE

The furcation involvement of 100 molars in 25 patients suffering from moderate to advanced periodontitis was investigated. The horizontal pr obing attachment level (PAL-H) within the furcations was assessed 2x w ithin 2 weeks using the pressure-calibrated (0.25 N) flexible plastic universal explorer version of the TPS probe (TPS). To determine the me asurement error of PAL-H assessments, the standard deviation of single measurements was calculated. The measurements were repeated using a c olour-coded Nabers probe and compared to the TPS assessments. 253 furc ations were evaluated (100 buucal, 47 lingual, 53 mesiolingual and 53 distolingual, respectively). For buccal, lingual, mesiolingual and dis tolingual furcations, the standard deviations were 0.486 mm, 0.598 mm, 0.846 mm, 1.039 mm, respectively Measurement error was less in buccal and lingual furcations than in mesiolingual and distolingual sites (p <0.005). The agreement of replicate measurements of furcation degrees was excellent for buccal and lingual furcations (weighted kappa [stand ard error] 0.824 [0.076] and 0.779 [0.107], respectively), but only mo derate for mesiolingual and distolingual furcations (weighted kappa 0. 688 [0.096] and 0.544 [0.101], respectively). Only in distolingual sit es there was a significant (p<0.025; paired t-test) underestimation of PAL-H by the TPS as compared to the Nabers probe. At all locations th e TPS underestimated furcation degrees significantly (p<0.1; Stuart-Ma xwell's chi(2)) as compared to Nabers probe. Measurement error of mesi olingual and distolingual furcations was significantly higher than of. buccal or lingual sites. The reproducibility of PAL-H measurements in furcations using TPS is comparable to data published for scorings wit h colour-coded Nabers probes. Through and through furcations are likel y to be underestimated by using the flexible plastic version of the TP S probe. Hence, it seems to be unsuitable for a proper assessment of t he degree of furcation involvement.