Porphyromonas gingivalis dihydroceramides induce apoptosis in endothelial cells.

Porphyromonas gingivalis dihydroceramides are found in extracts of calculus-contaminated root surfaces, diseased gingival tissue, and atherosclerotic plaques. These ceramides have been shown to promote inflammatory secretory responses in gingival fibroblasts. Little is known about their effects on the vascular system. We tested the hypothesis that P. gingivalis lipids induce apoptosis of human endothelial cells, and investigated the effects of extracted and purified P. gingivalis lipids on human umbilical vein endothelial cells. P. gingivalis phosphoglycerol dihydroceramides induced apoptosis, but not necrosis, in endothelial cells. Early apoptotic cells showed exposure of phosphatidylserine on the cell surface, followed by the cleavage of procaspases 3, 6, and 9. The release of apoptosis-inducing factor was increased, suggesting mitochondrial involvement. Different caspase inhibitors and cAMP elevation blocked DNA fragmentation. Moreover, N-acetylcysteine significantly reduced apoptosis, suggesting a role for reactive oxygen species in this process. Analysis of these data indicates that dihydroceramides may be important virulence factors of P. gingivalis.

Repeated local metronidazole-therapy as adjunct to scaling and root planing in maintenance patients.

The purpose of this investigation was to evaluate the effect of local antibiotic therapy with metronidazole adjunctively to scaling and root planing (SRP) versus mechanical treatment alone. 30 maintenance-patients were included in this single-blind study. The subjects had to comply with the following criteria: 2 non-adjacent sites with a probing depth > or =6 mm with bleeding on probing in separate quadrants, no periodontal therapy within the last 3 months, and no antibiotic therapy within the last 6 months. After randomization, the study sites were assigned to one of the following 2 treatments: SRP plus subgingival application of metronidazole 25% dental gel (Elyzol) 5x during 10 days (test site) or SRP alone (control site). Subgingival microbiological samples were taken prior to, and 21 days and 3 months after scaling. The samples were analyzed with a commercial chair-side ELISA (Evalusite) for Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans. Probing pocket depth (PPD), attachment level (AL) and bleeding on probing (BOP) were recorded at baseline and 3 months later. PPD reduction and AL-gain were statistically significant (p<0.001) after both treatments. However, there were no statistically significant differences between them. The same observation was made for BOP. P. gingivalis was reduced significantly after both treatments without statistically significant differences. P. intermedia was reduced significantly only after SRP. A. actinomycetemcomitans was not reduced significantly after either treatment. In conclusion, the repeated local application of metronidazole as an adjunct to SRP and the mechanical treatment alone showed similar clinical and microbiological effects without statistically significant differences with the exception of P. intermedia.

Comparative antiplaque effectiveness of an essential oil and an amine fluoride/stannous fluoride mouthrinse.

The adjunctive use of antimicrobial mouthrinses to help control supragingival plaque and gingivitis has been shown to contribute significantly to patients' daily oral hygiene regimens. This controlled clinical study used an observer-blind, randomized, cross-over design in a 4-day plaque regrowth model to determine the relative efficacies of an essential oil-containing mouthrinse (Listerine Antiseptic) and an amine fluoride/stannous fluoride-containing mouthrinse (Meridol) in inhibiting the development of supragingival plaque. A 0.1% chlorhexidine mouthrinse (Chlorhexamed-Fluid) was used as a positive control, and a 5% hydroalcohol solution was used as a negative control. Dosing for each of the test mouthrinses was based on the manufacturers' label directions. Because the volume and rinse time for each of the test mouthrinses were different, each test mouthrinse had its own negative control group. On day 1 of each test period, subjects received an oral soft and hard tissue examination and a dental prophylaxis to remove all plaque, calculus, and extrinsic stain. Starting the same day, subjects refrained from all mechanical oral hygiene procedures for the next 4 days and rinsed 2x daily under supervision with their randomly-assigned mouthrinse. On day 5, each subject received a plaque assessment as well as an oral examination to assess side effects. Each test period was separated by a 2-week washout period. 23 volunteers with a median age of 26 years completed the study. Compared to the respective placebos, the median percent plaque reductions at 5 days were 23.0%, 12.2%, and 38.2% for the essential oil, amine/stannous fluoride, and chlorhexidine rinses, respectively. The plaque reductions seen in the essential oil and chlorhexidine rinse groups were statistically significant (p < 0.001), while the plaque reduction in the amine/stannous fluoride rinse group was not statistically significant (p > 0.05). Additionally, the essential oil rinse was significantly more effective (p < 0.001) than the amine/stannous fluoride rinse in inhibiting plaque accumulation in this clinical model.

Molecular epidemiology of oral treponemes associated with periodontal disease.

Periodontitis, a disease responsible for tooth loss worldwide, is characterized by chronic inflammation of the periodontium, eventually leading to destruction of periodontal ligaments and supporting alveolar bone. Spirochetes, identified by dark-field microscopy as being the most predominant bacteria in advanced lesions, are thought to play a causative role. Various spirochetal morphotypes were observed, but most of these morphotypes are as yet uncultivable. To assess the role of these organisms we designed oligonucleotide probes for the identification of both cultivable and so far uncultivable spirochetes in periodontitis patients. Subgingival plaque specimens taken from diseased sites (n = 200) and healthy control sites (n = 44) from 53 patients with rapidly progressive periodontitis (RPP) were submitted to direct in situ hybridization or dot blot hybridization after prior amplification with eubacterial primers. Spirochetes were found in all patients, but their distributions varied considerably. Parallel use of oligonucleotide probes specific for cultivable or so far uncultivable treponemes suggested the presence of novel yet unknown organisms at a high frequency. These uncultivable treponemes were visualized by fluorescence in situ hybridization, and their morphologies, sizes, and numbers could be estimated. All RPP patients included in this study harbored oral treponemes that represent either novel species, e.g., Treponema maltophilum, or uncultivable phylotypes. Therefore, it is necessary to include these organisms in etiologic considerations and to strengthen efforts to cultivate these as yet uncultivable treponemes.