Influence of contrast enhancement and pseudocolor transformation on the diagnosis with digital subtraction images (DSI).

This study evaluated the influence of the image processing step of digital subtraction images on inter- and intraexaminer agreement in the interpretation of alveolar bone changes. 52 pairs of standardized radiographs from various clinical trials were included. Six dentists were invited to interpret the images projected as slides in random order. Display one demonstrated the slide of the digitized baseline radiograph and the follow-up image. Display two showed the regular digital subtraction image. Display three represented a grey level contrast enhanced version and displays four and five were pseudo/color enhanced subtraction images. Applying kappa-statistics and multiple regression analysis it was demonstrated that better agreements were obtained when the two color coded displays of subtraction images were shown to the interpreters. The image interpretation was performed in two series. For the first evaluation the interpreters were not informed about the therapy provided nor the time elapsed between taking the pairs of standardized radiographs. In the second series this information was provided. It could be demonstrated that the agreement in the diagnosis of bone change was less influenced by the knowledge about the clinical information if the two color-converted versions of subtracted images were evaluated. Thus, it was concluded that image processing of subtraction images using color enhancement might improve agreement in the diagnostic task. The color coded images were less influenced by the bias in the interpretation of an expected change. The decision making process might be more objective when using color enhanced subtraction images.link_to_subscribed_fulltex

The subgingival microflora and gingival crevicular fluid cytokines in refractory periodontitis

Refractory periodontitis manifests as a rapid, unrelenting, progressive loss of attachment despite the type and frequency of therapy. This study examined possible relationships between cytokine levels in gingival crevicular fluid (GCF), occurrence of specific periodontopathic microflora, and disease activity in patients with refractory periodontitis. Refractory periodontitis patients (7 male and 3 female) were selected on the basis of history and longitudinal clinical observations. In each patient, 2 teeth with pocket depths greater than 6 mm were selected and individual acrylic stents were fabricated with reference grooves for each site. The sites were examined at both baseline and 3 months later. The pattern and amount of alveolar bone resorption were assayed by quantitative digital subtraction radiography. Pocket depth and attachment loss were measured with a Florida Probe. The gingival index was measured at 4 sites around each sample tooth. Sites were divided into active sites (> or = 2.1 mm loss of attachment in 3 months) or inactive sites (< or = 2.0 mm loss of attachment in 3 months). The distribution and prevalence of the predominant microflora in active and inactive sites were compared using anaerobic culture and indirect immunofluorescence. Interleukin-1 beta, 2, 4, 6 and tumor necrosis factor-alpha (TNF-alpha) levels in gingival crevicular fluid (GCF) were quantified by ELISA. Prevotella intermedia and Eikenella corrodens significantly decreased in inactive sites but remained the same in active sites after 3 months. The active sites revealed significantly higher GCF levels of IL-2 and IL-6 than inactive sites at both baseline and at 3 months. IL-1 beta was also significantly greater in active sites than in inactive sites at 3 months. Alveolar bone loss in active sites correlated with increased GCF levels of IL-1 beta and IL-2. These results suggest that GCF levels of IL-1 beta, IL-2 and IL-6 and P. intermedia and E. corrodens in subgingival plaque may serve as possible indicators of disease activity in refractory periodontitis.8