Prevalence and antibiotic susceptibility trends of periodontal pathogens in the subgingival microbiota of German periodontitis patients: A retrospective surveillance study.

OBJECTIVE: This retrospective surveillance study aimed to follow periodontitis-associated bacterial profiles and to identify time-dependent changes in antibiotic susceptibility patterns. MATERIALS AND METHODS: From 2008 to 2015, bacterial specimen from deep periodontal pockets were collected from a total of 7804 German adults diagnosed with periodontitis. Presence of selected bacteria was confirmed by anaerobic culture and nucleic acid amplification. Antimicrobial susceptibility of clinical isolates was tested by disc diffusion with antibiotics used for the treatment of periodontitis and oral infections. The prevalences of periodontal pathogens were calculated and temporal evolution of antimicrobial susceptibility towards amoxicillin, amoxicillin/clavulanic acid, metronidazole, doxycycline, clindamycin, azithromycin, ciprofloxacin and ampicillin was analysed with logistic regression. RESULTS: The prevalence of patients harbouring bacteria was 95.9% Fusobacterium nucleatum, 88.0% Tannerella forsythia, 76.4% Treponema denticola, 76.5%, Campylobacter rectus, 76.0% Eikenella corrodens, 75.0% Capnocytophaga spp., 68.2% Porphyromonas gingivalis, 57.7% Peptostreptococcus micros, 43.1% Prevotella intermedia, 30.4% Eubacterium nodatum and 21.5% Aggregatibacter actinomycetemcomitans. In 63.5% of patients, one or more isolates were not susceptible to at least one of the antibiotics tested. The data further revealed a trend towards decreasing susceptibility profiles (p < 0.05) with antibiotic non-susceptibilities in 37% of patients in 2008 and in 70% in 2015. CONCLUSIONS: The present study confirmed a high prevalence of periodontal pathogens in the subgingival microbiota of German periodontitis patients. The data revealed an incremental increase in isolates displaying resistance to some antibiotics but no relevant change in susceptibility to amoxicillin and metronidazole.

Half a century of Scots pine forest ecosystem monitoring reveals long-term effects of atmospheric deposition and climate change.

At two forest sites in Germany (Pfaffenwinkel, Pustert) stocked with mature Scots pine (Pinus sylvestris L.), we investigated changes of topsoil chemistry during the recent 40 years by soil inventories conducted on replicated control plots of fertilization experiments, allowing a statistical analysis. Additionally, we monitored the nutritional status of both stands from 1964 until 2019 and quantified stand growth during the monitoring period by repeated stand inventories. Moreover, we monitored climate variables (air temperature and precipitation) and calculated annual climatic water balances from 1991 to 2019. Atmospheric nitrogen (N) and sulfur (S) deposition between 1964 and 2019 was estimated for the period 1969-2019 by combining annual deposition measurements conducted in 1985-1987 and 2004 with long-term deposition records from long-term forest monitoring stations. We investigated interrelations between topsoil chemistry, stand nutrition, stand growth, deposition, and climate trends. At both sites, the onset of the new millennium was a turning point of important biogeochemical processes. Topsoil acidification turned into re-alkalinization, soil organic matter (SOM) accumulation stopped, and likely turned into SOM depletion. In the new millennium, topsoil stocks of S and plant-available phosphorus (P) as well as S and P concentrations in Scots pine foliage decreased substantially; yet, age-referenced stand growth remained at levels far above those expected from yield table data. Tree P and S nutrition as well as climate change (increased temperature and drought stress) have replaced soil acidification as major future challenges for both forests. Understanding of P and S cycling and water fluxes in forest ecosystems, and consideration of these issues in forest management is important for successfully tackling the new challenges. Our study illustrates the importance of long-term forest monitoring to identify slow, but substantial changes of forest biogeochemistry driven by natural and anthropogenic global change.

Vulnerability of dynamic genetic conservation units of forest trees in Europe to climate change.

A transnational network of genetic conservation units for forest trees was recently documented in Europe aiming at the conservation of evolutionary processes and the adaptive potential of natural or man-made tree populations. In this study, we quantified the vulnerability of individual conservation units and the whole network to climate change using climate favourability models and the estimated velocity of climate change. Compared to the overall climate niche of the analysed target species populations at the warm and dry end of the species niche are underrepresented in the network. However, by 2100, target species in 33-65 % of conservation units, mostly located in southern Europe, will be at the limit or outside the species' current climatic niche as demonstrated by favourabilities below required model sensitivities of 95%. The highest average decrease in favourabilities throughout the network can be expected for coniferous trees although they are mainly occurring within units in mountainous landscapes for which we estimated lower velocities of change. Generally, the species-specific estimates of favourabilities showed only low correlations to the velocity of climate change in individual units, indicating that both vulnerability measures should be considered for climate risk analysis. The variation in favourabilities among target species within the same conservation units is expected to increase with climate change and will likely require a prioritization among co-occurring species. The present results suggest that there is a strong need to intensify monitoring efforts and to develop additional conservation measures for populations in the most vulnerable units. Also, our results call for continued transnational actions for genetic conservation of European forest trees, including the establishment of dynamic conservation populations outside the current species distribution ranges within European assisted migration schemes.

Temporary Root Canal Obturation with a Calcium Hydroxide-Based Dressing: A Randomized Controlled Clinical Trial.

Successful bacterial inactivation or elimination is essential for successful outcomes in endodontics. This study investigated the efficacy of a calcium hydroxide paste (Ca(OH)2) as a temporary medical dressing for 1 week after chemomechanical root canal treatment (CMRCT). Microbiological samples from 26 patients were collected after endodontic emergency treatment as follows: (1) removal of the provisional filling material; (2) CMRCT; (3) irrigation with sodium hypochlorite I (3%); (4) medicinal insertion of Ca(OH)2; and (5) irrigation with sodium hypochlorite II (3%). A microbiological examination was carried out after the specimens had been taken from the root canals via saline and sterile paper points. CMRCT resulted in a significant reduction in total bacterial load (TBL) in the root canal (p < 0.05). Additional irrigation (3) resulted in a further significant reduction in TBL (p < 0.05). In contrast, Ca(OH)2 medication did not prevent the bacterial load from returning to the previous level immediately after CMRCT, but did not increase above that level either (p < 0.05). However, the increase in TBL was significant (p < 0.05) in comparison with the disinfection groups (I/II). Administration of Ca(OH)2 for 1 week shows that in combination with an additional disinfection procedure, an increase in TBL must be expected, but not above the level of conditions after CMRCT.

Prevalence and Antibiotic Susceptibility Trends of Selected Enterobacteriaceae, Enterococci, and Candida albicans in the Subgingival Microbiota of German Periodontitis Patients: A Retrospective Surveillance Study.

The periodontal microbiota is ecologically diverse and may facilitate colonization by bacteria of enteric origin (Enterobacteriaceae, Enterococci) and co-infections with Candida albicans, possibly producing subgingival biofilms with high antimicrobial tolerance. This retrospective surveillance study followed periodontitis-associated superinfection profiles in a large patient sample. From 2008 to 2015, biofilm samples from deep periodontal pockets were collected from a total of 16,612 German adults diagnosed with periodontitis. The presence of selected Enterobacteriaceae, Enterococci, and Candida albicans was confirmed in overnight cultures. Antimicrobial susceptibility of these clinical isolates was tested by disk diffusion with antibiotics routinely used for treatment of oral infections, e.g., amoxicillin (AML), amoxicillin/clavulanic acid (AMC), doxycycline (DO), and ciprofloxacin (CIP). The mean annual prevalence of patients harboring Enterobacteriaceae in periodontal plaques was 11.5% in total and ranged from 2.5% for Enterobacter cloacae to 3.6% for Klebsiella oxytoca, 1.1% for Klebsiella pneumoniae, 2.8% for Serratia marcescens, and 1.5% for Serratia liquefaciens. In comparison, the mean detection rates for microbiota typically found in the oral cavity were higher, e.g., 5.6% for Enterococcus spp. and 21.8% for Candida albicans. Among the Enterobacteriaceae, species harboring intrinsic resistance to AML (Enterobacter spp., Klebsiella spp., Serratia spp.) were predominant. Non-susceptibility to AMC was observed for Serratia spp. and Enterobacter cloacae. By contrast, Enterococcus spp. only showed non-susceptibility to DO and CIP. Trends for increasing resistance were found to AML in Serratia liquefaciens and to DO in Enterococcus spp. Trend analysis showed decreasing resistance to AMC in Serratia liquefaciens and Klebsiella oxytoca; and to DO in Serratia marcescens, liquefaciens, and Enterobacter cloacae. This study confirms the low but consistent presence of Enterobacteriaceae and Enterococci among the subgingival microbiota recovered from periodontitis specimen. Although their pathogenetic role in periodontal lesions remains unclear, their presence in the oral cavity should be recognized as a potential reservoir for development and spread of antibiotic resistance in light of antibiotic usage in oral infections.

Impact of Adjunctive Laser Irradiation on the Bacterial Load of Dental Root Canals: A Randomized Controlled Clinical Trial.

Successful root canal treatment depends on the adequate elimination of pathogenic bacteria. This study evaluated the effectiveness of a novel 445-nm semiconductor laser in reducing bacteria after chemomechanical root canal treatment. Microbiological specimens from 57 patients were collected after emergency endodontic treatment, in the following sequence: 1, removal of the temporary filling material; 2, chemomechanical treatment; 3, rinsing with sodium hypochlorite (3%) along with one of three adjuvant protocols (n = 19 in each group). The adjuvant procedures were: (a) sodium hypochlorite rinsing alone (3%); (b) laser irradiation; (c) combined sodium hypochlorite rinsing and laser irradiation. The diode laser was set to 0.59 W in continuous-wave mode (CW) for 4 × 10 s. After the flooding of the root canal with saline, specimens were collected using paper points and analyzed microbiologically. Statistically significant reductions in the bacterial load were observed in all three groups (p < 0.05): 80.5% with sodium hypochlorite rinsing alone and 58.2% with laser therapy. Both results were lower than with the combination of sodium hypochlorite rinsing and 445-nm laser irradiation, at 92.7% (p < 0.05). Additional disinfection of the root canal can thus be achieved with 445-nm laser irradiation after conventional chemical disinfection with sodium hypochlorite solution.

Antimicrobial Impact of Different Air-Polishing Powders in a Subgingival Biofilm Model.

Subgingival air-polishing devices (SAPD) can reduce bacterial biofilms and thus support periodontal healing. The authors of this study evaluated the effectiveness of the glycine-based and trehalose-based air-polishing powders in removing pathogenic bacteria in a subgingival biofilm model. We treated 56 subgingival pockets in porcine jaws with SAPD. Subgingival air polishing was performed in three groups of 13 pockets each: I, glycine-based powder; II, trehalose-based powder; and III, water alone. Another group (IV) served as untreated controls. Prior to air polishing, inoculated titanium bars were inserted into the pockets containing periopathogenic bacteria such as Porphyromonas gingivalis and Tannerella forsythia. Remaining bacteria were evaluated using real-time PCR. The numbers of remaining bacteria depended on the treatment procedure, with the lowest number of total bacteria in group I (median: 1.96 × 106 CFU; min: 1.46 × 105; max: 9.30 × 106). Both polishing powders in groups I and II (median: 1.36 × 107 CFU; min: 5.22 × 105; max: 7.50 × 107) showed a statistically significantly lower total bacterial load in comparison to both group IV (median: 2.02 × 108 CFU; min: 5.14 × 107; max: 4.51 × 108; p < 0.05) and group III (median: 4.58 × 107 CFU; min: 2.00 × 106; max: 3.06 × 108; p < 0.05). Both subgingival air-polishing powders investigated can reduce periopathogenic bacteria and thus support antimicrobial therapy approaches in periodontal treatment regimens.

Comparison of different laser-based photochemical systems for periodontal treatment.

PURPOSE: The main aim in periodontitis treatment is to remove supragingival and subgingival biofilm. Mechanical treatment to eliminate pathogenic bacteria is limited by morphological conditions on the root surface. This study assessed the antibacterial effectiveness of different laser-based photochemical systems, particularly a novel curcumin-based option. METHODS: Ninety-one titanium bars were inoculated with an artificial biofilm of common pathogenic periodontal bacteria and inserted into an artificial periodontal pocket model. The following groups (n = 13) were tested: 1, curcumin solution plus SLB laser irradiation (C + L; 445 nm, 0.6 W, 25% duty cycle, 100 Hz, 10 s); 2, curcumin solution (Cur); 3, dimethyl sulfoxide solution (DMSO); 4, SiroLaser Blue (SLB) - laser irradiation (445 nm, 0.6 W, 25% duty cycle, 100 Hz, 10 s); 5, antimicrobial photodynamic therapy (aPDT); 6, antimicrobial photothermal therapy (aPTT); 7, control. The samples were stored in Eppendorf tubes and analyzed microbiologically using quantitative real-time polymerase chain reaction (PCR). The main parameter for analyzing group differences was the total bacterial load. Statistical analysis was performed with nonparametric methods. RESULTS: Statistically significant reductions in bacterial count were observed in all experimental groups (p < 0.05). The mean percentage reductions were as follows: SLB, 95.03%; aPDT, 83.91%; DMSO, 95.69%; C + L, 97.15%. No statistically significant differences in bacteria reduction were observed for laser alone (SLB), DMSO, or curcumin with or without additional laser irradiation. CONCLUSIONS: The greatest antibacterial efficacy was observed in samples treated with aPTT. Using curcumin as a photosensitizing agent for 445 nm laser irradiation did not result in improved antibacterial effectiveness in comparison with laser alone.

Efficiency of the Vector -system compared with conventional subgingival debridement in vitro and in vivo.

OBJECTIVE: To assess the efficacy of the novel ultrasonic Vector -system system for subgingival debridement and to compare the results with conventional periodontal instrumentation in vitro and in vivo. MATERIAL AND METHODS: Forty extracted human teeth were treated in vitro: Vector -system with polishing (VP) and abrasive fluid (VA), conventional ultrasonic system (U) and hand instrument (H). At intervals of 40 s, calculus removal was assessed using a 3D laser scanning device. Eight single-rooted teeth were treated in vivo with the Vector -system or hand instruments. Subgingival plaque samples were obtained for microbiological evaluation. After extraction, residual calculus was assessed by means of digitized planimetry. RESULTS: In vitro efficiency of hand instruments was statistically higher compared with the conventional ultrasonic system (p < 0.05) and the Vector -system with no difference between U and VA (p > 0.05) and VA and VP (p > 0.05). Residual calculus following in vivo instrumentation was not different in the Vector and the hand instrument group (p > 0.05) but treatment time with the Vector -system was statistically higher (p < 0.05). A similar reduction of periopathogenic bacteria could be observed in both groups. CONCLUSION: Using the Vector -system, root surfaces can be debrided as thoroughly as with conventional instruments. However, treatment is more time consuming than conventional debridement.

Efficacy of subgingival calculus removal with Er:YAG laser compared to mechanical debridement: an in situ study.

OBJECTIVES: The aim of the present study was to compare the effectiveness of subgingival calculus removal from periodontally involved root surfaces with an Er:YAG laser compared to hand instrumentation in situ. METHODS: The mesial and distal surfaces of 30 single-rooted teeth with untreated periodontitis were treated either by hand instrumentation (scaling and root planing (SRP)) or by Er:YAG laser irradiation with the aim of achieving a calculus-free root surface. Subgingival plaque samples were obtained before and immediately after treatment for microbiological evaluation by culture and DNA probe analysis. The teeth were extracted and the residual calculus was measured by means of digitized planimetry. The morphology of the root surface was evaluated by scanning electron microscopy, and undecalcified sections were analyzed to determine residual calculus and the extent of cementum removal following both treatments. RESULTS: Following laser irradiation, 68.4+/-14.4% of the root surface was calculus free in contrast to 93.9+/-3.7% after SRP when both treatments were performed for the same time (2:15+/-1:00 min). If laser irradiation was allowed twice the time used for hand instrumentation, 83.3+/-5.7% of the root surface was devoid of calculus. The effectiveness of both treatments was not related to initial probing depth. The histologic evaluation showed that after SRP 73.2% of root dentin was completely denuded from cementum, while only a minimal cementum reduction was apparent after laser irradiation. Both treatment modalities resulted in a similar reduction of periodontopathogens. DISCUSSION: The present investigation could demonstrate the in vivo capability of the Er:YAG laser to remove calculus from periodontally involved root surfaces, although the effectiveness did not reach that achieved by hand instrumentation. The lack of cementum removal in contrast to SRP may qualify the laser as an alternative approach during supportive periodontal therapy.