Dual release of daptomycin and BMP-2 from a composite of ß-TCP ceramic and ADA gelatin.

BACKGROUND: Antibiotic-containing carrier systems are one option that offers the advantage of releasing active ingredients over a longer period of time. In vitro sustained drug release from a carrier system consisting of microporous ß-TCP ceramic and alginate has been reported in previous works. Alginate dialdehyde (ADA) gelatin gel showed both better mechanical properties when loaded into a ß-TCP ceramic and higher biodegradability than pure alginate. METHODS: Dual release of daptomycin and BMP-2 was measured on days 1, 2, 3, 6, 9, 14, 21, and 28 by HPLC and ELISA. After release, the microbial efficacy of the daptomycin was verified and the biocompatibility of the composite was tested in cell culture. RESULTS: Daptomycin and the model compound FITC protein A (n = 30) were released from the composite over 28 days. A Daptomycin release above the minimum inhibitory concentration (MIC) by day 9 and a burst release of 71.7 ± 5.9% were observed in the loaded ceramics. Low concentrations of BMP-2 were released from the loaded ceramics over 28 days.

Composite material consisting of microporous beta-TCP ceramic and alginate-dialdehyde-gelatin for controlled dual release of clindamycin and bone morphogenetic protein 2.

The aim of this study was to produce a composite of microporous ß-TCP filled with alginate-gelatin crosslinked hydrogel, clindamycin and bone morphogenetic protein (BMP-2) to prolong the drug-release behaviour for up to 28 days. The most promising alginate-di-aldehyde(ADA)-gelatin gel for drug release from microcapsules was used to fill microporous ß-TCP ceramics under directional flow in a special loading chamber. Dual release of clindamycin and BMP-2 was measured on days 1, 2, 3, 6, 9, 14, 21 and 28 by high performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA). After release, the microbial efficacy of the clindamycin was checked and the biocompatibility of the composite was tested in cell culture. Clindamycin and the model substance FITC-protein A were released from microcapsules over 28 days. The clindamycin burst release was 43 ± 1%. For the loaded ceramics, a clindamycin release above the minimal inhibitory concentration (MIC) until day 9 and a burst release of 90.56 ± 2.96% were detected. BMP-2 was released from the loaded ceramics in low concentrations over 28 days. The release of active substances from ß-TCP and hydrogel have already been extensively studied. Directional flow loading is a special procedure in which the ceramic could act as a stabilizer in the bone and, as a biodegradable system, enables a single-stage surgical procedure. Whether ADA-gelatin gel is suitable for this procedure as a more biodegradable alternative to pure alginate or whether a dual release is possible in this composite has not yet been investigated.

Optimizing the use of low-frequency ultrasound for bacterial detachment of in vivo biofilms in dental research-a methodological study.

OBJECTIVES: Low-frequency, low-intensity ultrasound is commonly utilized in various dental research fields to remove biofilms from surfaces, but no clear recommendation exists in dental studies so far. Therefore, this study aims to optimize the sonication procedure for the dental field to efficiently detach bacteria while preserving viability. MATERIALS AND METHODS: Initial biofilm was formed in vivo on bovine enamel slabs (n = 6) which were worn by four healthy participants for 4 h and 24 h. The enamel slabs covered with biofilm were then ultrasonicated ex vivo for various time periods (0, 1, 2, 4, 6 min). Colony-forming units were determined for quantification, and bacteria were identified using MALDI-TOF. Scanning electron microscopic images were taken to also examine the efficiency of ultrasonications for different time periods. RESULTS: Ultrasonication for 1 min resulted in the highest bacterial counts, with at least 4.5-fold number compared to the non-sonicated control (p < 0.05). Most bacteria were detached within the first 2 min of sonication, but there were still bacteria detached afterwards, although significantly fewer (p < 0.0001). The highest bacterial diversity was observed after 1 and 2 min of sonication (p < 0.03). Longer sonication periods negatively affected bacterial counts of anaerobes, Gram-negative bacteria, and bacilli. Scanning electron microscopic images demonstrated the ability of ultrasound to desorb microorganisms, as well as revealing cell damage and remaining bacteria. CONCLUSIONS: With the use of low-frequency, low-intensity ultrasound, significantly higher bacterial counts and diversity can be reached. A shorter sonication time of 1 min shows the best results overall. CLINICAL RELEVANCE: This standardization is recommended to study initial oral biofilms aged up to 24 h to maximize the outcome of experiments and lead to better comparability of studies.

Improving the microbial sampling and analysis of secondary infected root canals by passive ultrasonic irrigation.

OBJECTIVE: The persistence of pathogenic microorganisms in root canals is the most common reason for the failure of root canal treatment and the necessity of a root filling treatment, which results in an uncertain prognosis due to technical complexity and the variety of highly adaptable microorganisms. This study evaluated the effect of passive ultrasonic irrigation (PUI) on the outcome of the microbial analysis of root canal-treated teeth with persistent or recurrent apical inflammation in vivo. MATERIALS AND METHODS: Sample collection was performed after root filling removal (sample S1, control group) and after PUI with NaCl (sample S2) using sterile paper points. In total, 19 samples were obtained. Quantification was performed by means of serial dilution of the samples. Subcultivated pure cultures were identified using MALDI-TOF MS complemented by the Vitek-2-System or PCR, followed by sequencing of the 16S rRNA gene. The results of the samples (S1 and S2) were evaluated regarding their bacterial count and composition. RESULTS: The total count of bacteria and the number of aerobic/facultative anaerobic microorganisms significantly increased in the S2-samples after application of PUI. The number of obligate anaerobic microorganisms showed an increase after PUI, although it was not significant. We detected 12 different aerobic/facultative anaerobic microorganisms before PUI, and in 21 cases after PUI. Two different obligate anaerobic microorganisms were found in S1 samples compared to nine different species in S2 samples. CONCLUSIONS: PUI is a powerful method for detaching bacteria in infected root canals and enables a more precise analysis of the etiology of persistent endodontic infections. CLINICAL RELEVANCE: This study indicates that PUI exerts a positive cleansing effect and adds to the accessibility of microorganisms during the application of bactericidal rinsing solution in root canal treatments.

The antimicrobial effect of Rosmarinus officinalis extracts on oral initial adhesion ex vivo.

OBJECTIVE: In the last few decades, there has been a growing worldwide interest in the use of plant extracts for the prevention of oral diseases. The main focus of this interest lies in the identification and isolation of substances that limit the formation of microbial biofilm which plays a major role in the development of caries, periodontitis, and peri-implantitis. In this clinical ex vivo study, we investigated the antimicrobial effects of Rosmarinus officinalis extract against oral microorganisms within in situ initial oral biofilms. MATERIALS AND METHODS: Initial in situ biofilm samples (2 h) from six healthy volunteers were treated ex vivo with R. officinalis extract at concentrations of 20 mg/ml and 30 mg/ml. The number of viable bacterial cells was determined by counting the colony-forming units. All surviving bacteria were isolated in pure cultures and identified using MALDI-TOF and biochemical testing procedures. Additionally, live/dead staining in combination with epifluorescence microscopy was used for visualizing the antimicrobial effects in the initial biofilms. RESULTS: The number of colony-forming units in the R. officinalis-treated biofilms was significantly lower than in the untreated controls (p < 0.001). The reduction range of log10 was 1.64-2.78 and 2.41-3.23 for aerobic and anaerobic bacteria, respectively. Regarding the bacterial composition, large intra- and interindividual variability were observed. Except for Campylobacter spp., the average amount of all bacterial taxa was lower after treatment with R. officinalis than in the untreated biofilms. A total of 49 different species were detected in the untreated biofilms, while only 11 bacterial species were detected in the R. officinalis-treated biofilms. Live/dead staining confirmed that the R. officinalis-treated biofilms had significantly lower numbers of surviving bacteria than the untreated biofilms. CONCLUSIONS: The treatment with R. officinalis extract has a significant potential to eliminate microbial oral initial biofilms. CLINICAL RELEVANCE: The results of this study encourage the use of R. officinalis extracts in biofilm control and thus in the treatment of caries and periodontitis as a herbal adjuvant to synthetic substances.

Effects of subgingival air-polishing with trehalose powder on oral biofilm during periodontal maintenance therapy: a randomized-controlled pilot study.

BACKGROUND: This pilot study was part of a larger study which compared the effect of subgingival air-polishing using trehalose powder with sonic scaling on clinical parameters during supportive periodontal therapy. Within this microbiological part of the investigation subgingival samples were taken from 10 participants to analyze the survival of different bacterial species after the two different treatments as a proof of principle. METHODS: In 10 participants two non-adjacent, single-root teeth requiring treatment (PD =5 mm with bleeding on probing (BOP) or > 5 mm) were selected following a split-mouth design and were treated either with a sonic scaler or air-polishing device and trehalose powder. For persistent pockets (PD =4 mm and BOP or > 4 mm), treatment was repeated after 3 months. Subgingival biofilm samples were taken at baseline (BL), subsequently and three and six months after treatment. After determination of the bacterial counts (TBL), isolated bacteria were identified by MALDI-TOF-MS. If unsuccessful, PCR and 16S rDNA sequencing were performed. RESULTS: In both treatment groups, TBL decreased immediately after treatment remaining at a lower level. This confirms the findings of the larger study regarding clinical parameters showing a comparable effect on PD, BOP and CAL. Immediately after treatment, the diversity of detected species decreased significantly more than in the sonic group (p = 0.03). After 3 months, the proportion of Gram-positive anaerobic rods was lower in the air-polishing group (powder/ sonic 7%/ 25.9%, p = 0.025). Also, there was a greater reduction of Gram-negative aerobic rods for this group at this time (air-polishing/ sonic - 0.91 / -0.23 Log10 cfu/ ml, p = 0.020). CONCLUSION: Within the limitations of this study air-polishing and sonic treatment seem to have a comparable effect on the subgingival oral biofilm during supportive periodontal treatment. TRIAL REGISTRATION: The study was registered in an international trial register (German Clinical Trial Register number DRKS 00006296) on 10th of June 2015. HTML&TRIAL_ID = DRKS00006296.

Compounds from Olea europaea and Pistacia lentiscus inhibit oral microbial growth.

BACKGROUND: In view of the increasing antibiotic resistance, the introduction of natural anti-infective agents has brought a new era in the treatment of bacterially derived oral diseases. METHODS: The aim of this study was to investigate the antimicrobial potential of five natural constituents of Olea europaea (oleuropein, maslinic acid, hydroxytyrosol, oleocanthal, oleacein) and three compounds of Pistacia lentiscus (24Z-isomasticadienolic acid, oleanolic acid, oleanonic aldehyde) against ten representative oral bacterial species and a Candida albicans strain. After the isolation and quality control of natural compounds, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay were performed. RESULTS: Among all O. europaea-derived constituents, maslinic acid was the most active (MIC = 4.9-312 µg mL- 1, MBC = 9.8-25 µg mL- 1) one against oral streptococci and anaerobic pathogenic bacteria (Porphyromonas gingivalis, Fusobacterium nucleatum, Parvimonas micra), while oleuropein, hydroxytyrosol, oleocanthal and oleacein showed milder, yet significant effects against P. gingivalis and F. nucleatum. Among all P. lentiscus compounds, oleanolic acid was the most effective one against almost all microorganisms with MIC values ranging from 9.8 µg mL- 1 (P. gingivalis) to 625 µg mL- 1 (F. nucleatum, P. micra). In the presence of 24Z-isomasticadienolic acid, a mean inhibitory concentration range of 2.4 µg mL- 1 to 625 µg mL- 1 was observed for strict anaerobia. The MIC value for 24Z-isomasticadienolic acid was estimated between 39 µg mL- 1 (Streptococcus sobrinus, Streptococcus oralis) and 78 µg mL- 1 (Streptococcus mutans). All tested compounds showed no effects against Prevotella intermedia. CONCLUSIONS: Overall, maslinic acid and oleanolic acid exerted the most significant inhibitory activity against the tested oral pathogens, especially streptococci and anaerobic oral microorganisms.

In Vitro Investigation of the Antimicrobial Effect of Three Bisphosphonates Against Different Bacterial Strains.

PURPOSE: Since the first descriptions of medication-related osteonecrosis of the jaw (MRONJ) in 2003, the pathogenesis has remained unanswered. Recent histomorphometric studies have found several microorganisms, including Actinomyces, Bacillus, Fusobacterium, Staphylococcus, Streptococcus, Selenomonas, Treponema, and Candida albicans in necrotic bone. Polymerase chain reaction studies have recently confirmed the occurrence of 48 genera. Only a few studies have examined the antimicrobial effect of bisphosphonates (BPs). The influence of bacterial growth on the etiology remains unclear. The aim of the present study was the in vitro investigation of the antimicrobial effect of 3 BPs against different bacterial strains. MATERIALS AND METHODS: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 48 strains from 40 species were determined in microdilution assays against pamidronic, ibandronic, and zoledronic acid. RESULTS: Growth of gram-positive oral microbiota, which account for most microorganisms in MRONJ, was present for 2 of 22 species; 6 of 26 gram-negative species and 9 of 13 anaerobes were inhibited. The MIC values were compared with the BP bone concentrations from previous reports. Of the 48 strains, 9 had an MIC or MBC less than the bone concentrations. CONCLUSIONS: The results of the present study have demonstrated that BPs have an inhibitory effect on selected bacterial species and might inhibit the growth of some relevant pathogens in osteonecrosis. However, most of the species tested were unaffected at the concentration levels assumed present in the human jawbone. The clinical relevance of these in vitro data will better be clarified with reliable data on the BP concentrations in the human jawbone. The present study has provided a first approach toward the assessment of the interaction of oral bacteria and BPs.

Association between high risk for preterm birth and changes in gingiva parameters during pregnancy-a prospective cohort study.

OBJECTIVES: The objective of this study was to investigate clinical and microbiological gingival changes during pregnancy in women without periodontal disease. Additionally, these parameters were to be compared in women with high risk for preterm birth and women with a normal course of pregnancy. METHOD AND MATERIALS: Group I consisted of 40 subjects at high risk for preterm birth, while group II involved 49 subjects with a normal course of pregnancy. The control group (III) was made up of 50 non-pregnant women. Clinical parameters (plaque index, gingival index, probing pocket depths, gingival swelling, bleeding on probing) and microbiological changes were monitored during pregnancy and 2-4 weeks after parturition. RESULTS: In the high-risk preterm group (I), 19 women could be included in data analysis. This group was compared to 41 women in the normal pregnancy group (II) and 50 non-pregnant women (III). Gingival inflammation was significantly higher in women with high risk for preterm birth (I) compared to non-risk pregnant women (II, p < 0.05). In addition, in this group (I), the subgingival amounts of Fusobacterium nucleatum (> 105) were found to be significantly higher after childbirth compared to non-pregnant women (p < 0.05). CONCLUSIONS: Even without having periodontal disease, women with high risk for preterm birth showed worse clinical values compared to non-risk pregnant and non-pregnant women and an increased detection of Fusobacterium nucleatum after delivery. CLINICAL RELEVANCE: High risk for preterm birth might be associated with the occurrence of increased gingival inflammation.

Examining the Composition of the Oral Microbiota as a Tool to Identify Responders to Dietary Changes.

BACKGROUND: The role of diet and nutrition in the prevention of oral diseases has recently gained increasing attention. Understanding the influence of diet on oral microbiota is essential for developing meaningful prevention approaches to oral diseases, and the identification of typical and atypical responders may contribute to this. METHODS: We used data from an experimental clinical study in which 11 participants were exposed to different dietary regimens in five consecutive phases. To analyse the influence of additional nutritional components, we examined changes in bacterial concentrations measured by culture techniques compared to a run-in phase. A measure of correspondence between the mean and individual patterns of the bacterial composition is introduced. RESULTS: The distance measures introduced showed clear differences between the subjects. In our data, two typical and three atypical responders appear to have been identified. CONCLUSIONS: The proposed method is suitable to identify typical and atypical responders, even in small datasets. We recommend routinely performing such analyses.

Antibiotic Resistance of Selected Bacteria after Treatment of the Supragingival Biofilm with Subinhibitory Chlorhexidine Concentrations.

Due to increasing rates of antibiotic resistance and very few novel developments of antibiotics, it is crucial to understand the mechanisms of resistance development. The aim of the present study was to investigate the adaptation of oral bacteria to the frequently used oral antiseptic chlorhexidine digluconate (CHX) and potential cross-adaptation to antibiotics after repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX. Plaque samples from six healthy donors were passaged for 10 days in subinhibitory concentrations of CHX, while passaging of plaque samples without CHX served as control. The surviving bacteria were cultured on agar plates and identified with Matrix-assisted Laser Desorption/Ionization-Time of Flight-Mass spectrometry (MALDI-TOF). Subsequently, the minimum inhibitory concentrations (MIC) of these isolates toward CHX were determined using a broth-microdilution method, and phenotypic antibiotic resistance was evaluated using the epsilometertest. Furthermore, biofilm-forming capacities were determined. Repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX led to the selection of oral bacteria with 2-fold up to 4-fold increased MICs toward CHX. Furthermore, these isolates showed up to 12-fold increased MICs towards some antibiotics such as erythromycin and clindamycin. Conversely, biofilm-forming capacity was decreased. In summary, this study shows that oral bacteria are able to adapt to CHX, while also decreasing their susceptibility to antibiotics.

A human bone infection organ model for biomaterial research.

The aim of this work was to establish an organ model for staphylococcal infection of human bone samples and to investigate the influence and efficacy of a microporous ß-tricalcium phosphate ceramic (ß-TCP, RMS Foundation) loaded with hydrogels (alginate, alginate-di-aldehyde (ADA)-gelatin) and clindamycin on infected human bone tissue over a period of 28 days. For this purpose, human tibia plateaus, collected during total knee replacement surgery, were used as a source of bone material. Samples were infected with S. aureus ATCC29213 and treated with differently loaded ß-TCP composites (alginate +/- clindamycin, ADA-gelatin +/- clindamycin, unloaded). The loading of the composites was carried out by means of a flow chamber. The infection was observed for 28 days, quantifying bacteria in the medium and the osseus material on day 1, 7, 14, 21 and 28. All samples were histologically processed for bone vitality evaluation. Bone infection could be consistently performed within the organ model. In addition, a strong reduction in bacterial counts was recorded in the groups treated with ADA-gelatin + clindamycin and alginate + clindamycin, while the bacterial count in the control groups remained constant. No significant differences between groups could be observed in the number of lacunae filled with osteocytes suggesting no differences in bone vitality among groups. In an ex-vivo human bone infection model, over a period of 28 days bacterial growth could be reduced by treatment with ADA-Gel + CLI and ALG + CLI -releasing ß-TCP composites. This could be relevant for its clinical use. Further work will be necessary to improve the loading of ß-TCP and the bone infection organ model itself. STATEMENT OF SIGNIFICANCE: The common treatment of bone infections is debridement and systemic administration of antibiotics. In some cases, antibiotic-containing carriers are already used, but these must be removed again. Our work is intended to show another treatment option. The scaffold we have developed, made of a calcium phosphate ceramic and a hydrogel as the active substance carrier, can, in addition to releasing the active substance, also assume a load-bearing function of the bone and is biodegradable. In addition, the model we developed can also be used for the analysis and treatment of bone infections other than those of the musculoskeletal system. More importantly, it can also serve as a substitute for previously used animal experiments.

Phenotypic Adaptation to Antiseptics and Effects on Biofilm Formation Capacity and Antibiotic Resistance in Clinical Isolates of Early Colonizers in Dental Plaque.

Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 clinical isolates of early colonizers of dental plaque (Streptococcus, Actinomyces, Rothia and Veillonella spp.) upon repeated exposure to subinhibitory concentrations of chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) over 10 passages using a modified microdilution method. Stability of phenotypic adaptation was re-evaluated after culture in antiseptic-free nutrient broth for 24 or 72 h. Strains showing 8-fold minimal inhibitory concentration (MIC)-increase were further examined regarding their biofilm formation capacity, phenotypic antibiotic resistance and presence of antibiotic resistance genes (ARGs). Eight-fold MIC-increases to CHX were detected in four Streptococcus isolates. These strains mostly exhibited significantly increased biofilm formation capacity compared to their respective wild-type strains. Phenotypic antibiotic resistance was detected to tetracycline and erythromycin, consistent with the detected ARGs. In conclusion, this study shows that clinical isolates of early colonizers of dental plaque can phenotypically adapt toward antiseptics such as CHX upon repeated exposure. The underlying mechanisms at genomic and transcriptomic levels need to be investigated in future studies.

New Bacterial Combinations in Secondary Endodontic Infections of Patients with a Recent Systematic Antibiotic Therapy.

INTRODUCTION: To date, the microbiota associated with persistent endodontic infections has only been analyzed in patients who did not receive any antibiotic therapy for at least 3 months before endodontic treatment. In this clinical study, secondary endodontic infections of patients who recently received systematic antibiotic therapy before endodontic treatment were analyzed and compared with the actual data available in the literature. METHODS: Root canal-filled teeth with periradicular lesions of 20 patients who were under systematic antibiotic therapy which ended 1-21 days before the endodontic treatment were studied. A wide range of antibiotics was administered, including amoxicillin, amoclav, amoxicillin/metronidazole, ampiclox (ampicillin and cloxacillin), doxycycline, tetracycline, ciprofloxacin, and azithromycin. Microorganisms were isolated according to standard protocols and identified using MALDI-TOF-MS. A narrative review of the literature was conducted to compare the results of this study with the data reported so far. RESULTS: The presence and concentrations of bacteria isolated from the infected root canals were comparable with those depicted in the literature, although the total colony-forming units number in saliva was rather low. The number of different bacterial species isolated and identified in each patient as well as the diversity over all patients did not show signs of any influence of the administered antibiotics. Weissella hellenica and Cellulomonas spp. were detected in root canals for the first time. Granulicatella adiacens and Dietzia spp., previously isolated from primary endodontic infections, were detected for the first time in persistent root canal infections in this patient group. CONCLUSIONS: The bacterial diversity reported to date in secondary endodontic infections should be extended with the new microbial composition revealed in endodontic patients who had recently received systematic antibiotic therapy.

Antimicrobial Effects of Inula viscosa Extract on the In Situ Initial Oral Biofilm.

Given the undesirable side effects of commercially used mouth rinses that include chemically synthesized antimicrobial compounds such as chlorhexidine, it is essential to discover novel antimicrobial substances based on plant extracts. The aim of this study was to examine the antimicrobial effect of Inula viscosa extract on the initial microbial adhesion in the oral cavity. Individual test splints were manufactured for the participants, on which disinfected bovine enamel samples were attached. After the initial microbial adhesion, the biofilm-covered oral samples were removed and treated with different concentrations (10, 20, and 30 mg/mL) of an I. viscosa extract for 10 min. Positive and negative controls were also sampled. Regarding the microbiological parameters, the colony-forming units (CFU) and vitality testing (live/dead staining) were examined in combination with fluorescence microscopy. An I. viscosa extract with a concentration of 30 mg/mL killed the bacteria of the initial adhesion at a rate of 99.99% (log10 CFU value of 1.837 ± 1.54). Compared to the negative control, no killing effects were determined after treatment with I. viscosa extract at concentrations of 10 mg/mL (log10 CFU value 3.776 ± 0.831; median 3.776) and 20 mg/mL (log10 CFU value 3.725 ± 0.300; median 3.711). The live/dead staining revealed a significant reduction (p < 0.0001) of vital adherent bacteria after treatment with 10 mg/mL of I. viscosa extract. After treatment with an I. viscosa extract with a concentration of 30 mg/mL, no vital bacteria could be detected. For the first time, significant antimicrobial effects on the initial microbial adhesion in in situ oral biofilms were reported for an I. viscosa extract.

Long-Term Use of Oral Hygiene Products Containing Stannous and Fluoride Ions: Effect on Viable Salivary Bacteria.

The aim of this randomized, controlled clinical trial was to isolate and identify viable microorganisms in the saliva of study participants that continuously used a stannous and fluoride ion (F/Sn)-containing toothpaste and mouth rinse over a period of three years in comparison to a control group that used stannous ion free preparations (noF/Sn) over the same time period. Each group (F/Sn and noF/Sn) included 16 participants that used the respective oral hygiene products over a 36-month period. Stimulated saliva samples were collected at baseline (T0) and after 36 months (T1) from all participants for microbiological examination. The microbial composition of the samples was analyzed using culture technique, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and 16S rDNA Polymerase Chain Reaction (PCR). There were only minor differences between both groups when comparing the absolute values of viable microbiota and bacterial composition. The treatment with F/Sn led to a slight decrease in disease-associated and a slight increase in health-associated bacteria. It was shown that the use of stannous ions had no negative effects on physiological oral microbiota even after prolonged use. In fact, a stabilizing effect of the oral hygiene products containing stannous ions on the health-associated oral microbiota could be expected.

A Log Ratio-Based Analysis of Individual Changes in the Composition of the Oral Microbiota in Different Dietary Phases.

BACKGROUND: Investigating the influence of nutrition on oral health has a long scientific history. Due to recent technical advances like sequencing techniques for the oral microbiota, this topic has gained scientific interest again. A basic challenge is to understand the influence of nutrition on the oral microbiota and on the interaction between the oral bacteria, which is also statistically challenging. METHODS: Log-transformed ratios of two bacteria concentrations are introduced as the basic analytic tool. The framework is illustrated by application in an experimental study exposing eleven participants to different nutrition schemes in five consecutive phases. RESULTS: The method could be sufficiently used to analyse the interrelation between the bacteria and to identify some bacterial groups with the same as well as different reactions to additional dietary components. It was found that the strongest changes in bacterial concentrations were achieved by the additional consumption of dairy products. CONCLUSION: A log ratio-based analysis offers insights into the relation of different bacteria while taking specific features of compositional data into account. The presented methods allow becoming independent of the behaviour of other bacteria, which is a disadvantage of common analysis methods of compositions. The results indicate that modulations of the oral biofilm microbiota due to nutrition change can be attained.

An antimicrobial effect from silver-coated toothbrush heads.

PURPOSE: To examine the antimicrobial effect of silver-coated toothbrush heads in vitro. METHODS: Comparisons were made between 62 silver-coated and 62 non-coated toothbrush heads which were contaminated by different standardized microbial suspensions. The following microorganisms were investigated: Streptococcus oralis, Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, Lactobacillus casei and Candida albicans. For cultivation of the microorganisms as well as for the subsequent determination of the colony forming units (CFUs), Columbia blood agar plates or Sabouraud agar were used. The cycle of daily toothbrushing was imitated by rinsing the brushes with 200 ml sterile tap water to reduce the number of microorganisms and the brushes were then placed upright to allow drying overnight. Colony counts were done initially (time 0) and again at 20 hours. The rinsing fluid was also examined in order to determine the decrease of microorganisms due to this step. All experiments were done twice and the means were calculated and statistically evaluated. RESULTS: There was no significant reduction in CFUs by silver-coated toothbrushes (P > 0.05) for all of the microorganisms tested. On the contrary, the colony counts for S. sanguis (P = 0.02) and C. albicans (P = 0.01) were significantly higher on silver-coated toothbrushes compared to the controls. Silver-coating in the current form did not improve any antimicrobial effects against residual bacteria present on the toothbrush head.

Microbial Composition of Oral Biofilms after Visible Light and Water-Filtered Infrared a Radiation (VIS+wIRA) in Combination with Indocyanine Green (ICG) as Photosensitizer.

In view of increasing antibiotic resistance, antimicrobial photodynamic therapy (aPDT) is an alternative treatment method used to eradicate the microbial community of oral biofilms that can be responsible for different oral infections. In order to investigate changes in the microbial composition after application of aPDT with visible light and water-filtered infrared A (VIS+wIRA) in combination with indocyanine green (ICG), oral microorganisms of the initial and mature biofilm were evaluated by mass spectrometry (MALDI-TOF-MS). To determine surviving microorganisms using MALDI-TOF-MS, an in situ biofilm was irradiated with VIS+wIRA for five minutes in the presence of ICG (300 and 450 µg/mL, respectively). Treatment with chlorhexidine (0.2%) served as positive control. Identified microorganisms of the initial biofilm treated with ICG showed a clear reduction in diversity. The microbial composition of the mature oral biofilm also showed changes after the implementation of aPDT, which mainly resulted in a shift in the percentage of bacterial species. The resulting destruction of the microbial balance within the oral biofilm by aPDT using VIS+wIRA and ICG can be seen as an advantageous supplementary approach in the adjunctive treatment of periodontitis and peri-implantitis.

Analysing the Relationship between Nutrition and the Microbial Composition of the Oral Biofilm-Insights from the Analysis of Individual Variability.

The influence of a change in nutrition on the oral microbiota are discussed in literature, but usually only changes of population mean values are reported. This paper introduces simple methods to also analyse and report the variability of patients' reactions considering data from the culture analysis of oral biofilm. The framework was illustrated by an experimental study exposing eleven participants to different nutrition schemes in five consecutive phases. Substantial inter-individual variations in the individual reactions were observed. A new coherence index made it possible to identify 14 instances where the direction of individual changes tended to coincide with the direction of the mean change with more than 95% probability. The heterogeneity in variability across different bacteria species was limited. This allowed us to develop recommendations for sample sizes in future studies. For studies measuring the concentration change of bacteria as a reaction to nutrition change, the use of replications and analysis of the variability is recommended. In order to detect moderate effects of a change in nutrition on the concentration of single bacterial taxa, 30 participants with three repetitions are often adequate. Insights into the relationship between nutrition and the microbial composition can be helpful for the development of dietary habits that promote the establishment of a healthy microbial flora and can therefore prevent the initiation of oral diseases such as caries and periodontitis.