Overall, the agreement between both test methods was excellent for A. actinomycetemcomitans and P. gingivalis, fair for T. forsythensis and poor for F. nucleatum and P. intermedia. The discrepancies in the results may be explained by the inability of cultivation methods to distinguish between close related taxa, and the problems of keeping periopathogenic bacteria viable, which is required for standard cultivation.

Overall, there was a relatively good agreement for the results of paper point and curet sampling. Thus, both techniques seem to be suitable for microbiological diagnostics.

The present study compared the recovery of six periodontal pathogens by paper point samples from two different aspects of periodontal lesions by quantitative real-time polymerase chain reaction (PCR). Twenty patients with untreated chronic periodontitis were randomized into two groups. Before subgingival instrumentation and after 10 weeks samples in group A were taken first with a paper point half length (HP) of the probing depth, then with a paper point full length (FP) at the same site. In group B sampling sequence was reversed. Analysis by real-time PCR enabled quantification of six bacteria as well as total bacterial count (TBC). Statistical analysis included t test, Kappa, and Spearman's correlations. Higher TBC could be harvested by use of FP than by HP (mean of differences of ln-transformed counts before therapy: -0.791, CI [-1.515, -0.068], SD 0.770, p = 0.034; after therapy: -0.563, CI [-1.151, 0.024], SD 0.625, p = 0.059). The plaque composition regarding total target pathogens was similar for both samples. Both, for TBC as well as for single target bacteria a strong positive correlation was found between HP and FP (Kappa, Spearman correlation: Aggregatibacter actinomycetemcomitans 0.807, 0.778; Fusobacterium nucleatum 0.573, 0.772; Porphyromonas gingivalis 0.733, 0.824; Prevotella intermedia 0.480, 0.756; Treponema denticola 0.807, 0.814; and Tannerella forsythia 0.692, 0.695). The recovery of target pathogens was similar following sampling at various depths of the periodontal lesion.