Microcalorimetric Determination of the Effects of Amoxicillin, Metronidazole, and Their Combination on In Vitro Biofilm

Simple Growth–Metabolism Relations Are Revealed by Conserved Patterns of Heat Flow from Cultured Microorganisms

Quantitative analyses of cell replication address the connection between metabolism and growth. Various growth models approximate time-dependent cell numbers in culture media, but physiological implications of the parametrizations are vague. In contrast, isothermal microcalorimetry (IMC) measures with unprecedented sensitivity the heat (enthalpy) release via chemical turnover in metabolizing cells. Hence, the metabolic activity can be studied independently of modeling the time-dependence of cell numbers. Unexpectedly, IMC traces of various origins exhibit conserved patterns when expressed in the enthalpy domain rather than the time domain, as exemplified by cultures of Lactococcus lactis (prokaryote), Trypanosoma congolese (protozoan) and non-growing Brassica napus (plant) cells. The data comply extraordinarily well with a dynamic Langmuir adsorption reaction model of nutrient uptake and catalytic turnover generalized here to the non-constancy of catalytic capacity. Formal relations to Michaelis–Menten kinetics and common analytical growth models are briefly discussed. The proposed formalism reproduces the “life span” of cultured microorganisms from exponential growth to metabolic decline by a succession of distinct metabolic phases following remarkably simple nutrient–metabolism relations. The analysis enables the development of advanced enzyme network models of unbalanced growth and has fundamental consequences for the derivation of toxicity measures and the transferability of metabolic activity data between laboratories.

Influence of different zirconia surface treatments on biofilm formation in vitro and in situ

OBJECTIVES

To determine if the surface treatment of zirconia affects biofilm formation in an in vitro three-species biofilm model and in situ.

MATERIAL AND METHODS

Zirconia surfaces considered for the transmucosal portion of a zirconia implant were compared with polished pure titanium grade 4 (Tp). Discs 13 mm in diameter of either polished (Zp), polished and heat-treated (Zpt), machined (Zm), machined and heat-treated (Zmt) and sandblasted, etched and heat-treated (Z14) zirconia were fabricated. Surface roughness and wettability of specimens was measured. Biofilm formation was evaluated by safranin staining and scanning electron microscopy (SEM) using a three-species model, and intraorally with 16 volunteers carrying oral splints in two independent experiments. Relative biofilm formation was compared with Kruskal-Wallis followed by Bonferroni post-hoc test (α=0.05).

RESULTS

In vitro biofilm formation with optical density values on Zp (0.14±0.01), Zpt (0.14±0.02), Zm (0.13±0.01) and Zmt (0.13±0.01) was significantly lower than on Tp (0.21±0.05) and Z14 (0.20±0.04) (p<0.05). In situ biofilm formation was significantly higher on Z14 (0.56±0.45) (p<0.05), while no significant differences in optical density were observed among Zp (0.25±0.20), Zm (0.36±0.34) and Tp (0.28±0.22). SEM analysis supported quantitative findings.

CONCLUSIONS

In the in vitro three-species biofilm model differences in material and surface roughness affected biofilm formation. In situ biofilm formation was mainly affected by the surface roughness of the specimens. Polishing of zirconia is recommended to reduce biofilm formation while heat-treatment has no significant effect.

Efficacy of Experimental Mouth Rinses on Caries-Related Biofilms in vitro

This study assessed the efficacy of tin and Polyethylenglycol (PEG-3) tallow aminopropylamine in different concentrations on Streptococcus mutans (S. mutans) biofilms to establish a new screening process for different antimicrobial agents and to gain more information on the antibacterial effects of these agents on cariogenic biofilms. Isothermal microcalorimetry (IMC) was used to determine differences in two growth parameters: lag time and growth rate; additionally, reduction in active biofilms was calculated. Experimental mouth rinses with 400 and 800 ppm tin derived from stannous fluoride (SnF₂) revealed results (43.4 and 49.9% active biofilm reduction, respectively) similar to meridol mouth rinse (400 ppm tin combined with 1,567 ppm PEG-3 tallow aminopropylamine; 55.3% active biofilm reduction) (p > 0.05), while no growth of S. mutans biofilms was detected during 72 h for samples treated with an experimental rinse containing 1,600 ppm tin (100% active biofilm reduction). Only the highest concentration (12,536 ppm) of rinses containing PEG-3 tallow aminopropylamine derived from amine fluoride (AmF) revealed comparable results to meridol (57.5% reduction in active biofilm). Lower concentrations of PEG-3 tallow aminopropylamine showed reductions of 16.9% for 3,134 ppm and 33.5% for 6,268 ppm. Maximum growth rate was significantly lower for all the samples containing SnF₂ than for the samples containing control biofilms (p < 0.05); no differences were found between the control and all the PEG-3 tallow aminopropylamine (p > 0.05). The growth parameters showed high reproducibility rates within the treated groups of biofilms and for the controls; thus, the screening method provided reliable results.

Classic vs. Novel Antibacterial Approaches for Eradicating Dental Biofilm as Adjunct to Periodontal Debridement: An Evidence-Based Overview

Periodontitis is a multifactorial chronic inflammatory disease that affects tooth-supporting soft/hard tissues of the dentition. The dental plaque biofilm is considered as a primary etiological factor in susceptible patients; however, other factors contribute to progression, such as diabetes and smoking. Current management utilizes mechanical biofilm removal as the gold standard of treatment. Antibacterial agents might be indicated in certain conditions as an adjunct to this mechanical approach. However, in view of the growing concern about bacterial resistance, alternative approaches have been investigated. Currently, a range of antimicrobial agents and protocols have been used in clinical management, but these remain largely non-validated. This review aimed to evaluate the efficacy of adjunctive antibiotic use in periodontal management and to compare them to recently suggested alternatives. Evidence from in vitro, observational and clinical trial studies suggests efficacy in the use of adjunctive antimicrobials in patients with grade C periodontitis of young age or where the associated risk factors are inconsistent with the amount of bone loss present. Meanwhile, alternative approaches such as photodynamic therapy, bacteriophage therapy and probiotics showed limited supportive evidence, and more studies are warranted to validate their efficiency.

Hyaluronic acid reduces inflammation and crevicular fluid IL-1β concentrations in peri-implantitis: a randomized controlled clinical trial

Purpose

This study investigated the effects of hyaluronic acid (HA) on peri-implant clinical variables and crevicular concentrations of the proinflammatory biomarkers interleukin (IL)-1β and tumor necrosis factor (TNF)-α in patients with peri-implantitis.

Methods

A randomized controlled trial was conducted in peri-implantitis patients. Patients were randomized to receive a 0.8% HA gel (test group), an excipient-based gel (control group 1), or no gel (control group 2). Clinical periodontal variables and marginal bone loss after 0, 45, and 90 days of treatment were assessed. IL-1β and TNF-α levels in crevicular fluid were measured by enzyme-linked immunosorbent assays at baseline and after 45 days of treatment. Clustering analysis was performed, considering the possibility of multiple implants in a single patient.

Results

Sixty-one patients with 100 dental implants were assigned to the test group, control group 1, or control group 2. Probing pocket depth (PPD) was significantly lower in the test group than in both control groups at 45 days (control 1: 95% CI, −1.66, −0.40 mm; control 2: 95% CI, −1.07, −0.01 mm) and 90 days (control 1: 95% CI, −1.72, −0.54 mm; control 2: 95% CI, −1.13, −0.15 mm). There was a trend towards less bleeding on probing in the test group than in control group 2 at 90 days (P=0.07). Implants with a PPD ≥5 mm showed higher levels of IL-1β in the control group 2 at 45 days than in the test group (P=0.04).

Conclusions

This study demonstrates for the first time that the topical application of a HA gel in the peri-implant pocket and around implants with peri-implantitis may reduce inflammation and crevicular fluid IL-1β levels.

Trial Registration

ClinicalTrials.gov Identifier: NCT03157193

Tolerance and Persister Formation in Oral Streptococci

The aim of this study was to analyze the potential influence of long-term exposure in subinhibitory concentrations of chlorhexidine on the emergence of tolerant and/or persistent cells in oral streptococci. The two oral streptococcal isolates S. mutans ATCC25175 and S. sobrinus ATCC33402 were incubated, after long-term subinhibitory exposure to chlorhexidine, in liquid growth media containing high concentrations of chlorhexidine. A distinct subpopulation of more chlorhexidine-tolerant cells could be detected in streptococci that had been previously exposed to subinhibitory concentrations of chlorhexidine but not in the control strains. These more biocide-tolerant and persisting microbial subpopulations might also arise in vivo. Therefore, the rational and proper use of antimicrobials in dentistry, especially when used over a long period of time, is crucial.

Rapid Calorimetric Detection of Bacterial Contamination: Influence of the Cultivation Technique

Modern isothermal microcalorimeters (IMC) are able to detect the metabolic heat of bacteria with an accuracy sufficient to recognize even the smallest traces of bacterial contamination of water, food, and medical samples. The modern IMC techniques are often superior to conventional detection methods in terms of the detection time, reliability, labor, and technical effort. What is missing is a systematic analysis of the influence of the cultivation conditions on calorimetric detection. For the acceptance of IMC techniques, it is advantageous if already standardized cultivation techniques can be combined with calorimetry. Here we performed such a systematic analysis using Lactobacillus plantarum as a model bacterium. Independent of the cultivation techniques, IMC detections were much faster for high bacterial concentrations (>102 CFU⋅mL-1) than visual detections. At low bacterial concentrations (<102 CFU⋅mL-1), detection times were approximately the same. Our data demonstrate that all kinds of traditional cultivation techniques like growth on agar (GOA) or in agar (GIA), in liquid media (GL) or on agar after enrichment via membrane filtration (GF) can be combined with IMC. The order of the detection times was GF < GIA ≈ GL ≈ GOA. The observed linear relationship between the calorimetric detection times and the initial bacterial concentrations can be used to quantify the bacterial contamination. Further investigations regarding the correlation between the filling level (in mm) of the calorimetric vessel and the specific maximum heat flow (in μW⋅g-1) illustrated two completely different results for liquid and solid media. Due to the better availability of substrates and the homogeneous distribution of bacteria growing in a liquid medium, the volume-related maximum heat flow was independent on the filling level of the calorimetric vessels. However, in a solid medium, the volume-related maximum heat flow approached a threshold and achieved a maximum at low filling levels. This fundamentally different behavior can be explained by the spatial limitation of the growth of bacterial colonies and the reduced substrate supply due to diffusion.

In vitro Assessment of Peri-implantitis Treatment Procedures: A Review

Background:

The prevalence of peri-implantitis is increasing continuously and such a biological complication significantly decreases implant survival and success. Although various treatment modalities have been identified for peri-implantitis, no completely efficient method has yet been established.

Objective:

The aim of this review was to evaluate the scientific literature regarding the in vitro effects of peri-implantitis treatment.

Methods:

A review of the literature was performed by using Google Scholar, PubMed/ MEDLINE and Science Direct databases. In vitro studies on peri-implantitis treatment modalities were selected. The search strategy identified 57 eligible studies. After selection, 21 articles met all the inclusion criteria and were included in the present review.

Results:

Included in vitro studies evaluated different types of peri-implantitis treatment modalities such as mechanical, chemical, combination and laser therapies. Combination therapies with the aid of adjuvants were found to be more effective compared to the studies that used only one type of treatment modality. Laser systems were also tested and displayed interesting results in terms of surface decontamination with a variability associated with selected parameters.

Conclusion:

This review was performed to evaluate the efficacy of the treatment modalities used for peri-implantitis in vitro. Although there are various effective treatment methods, none has been completely successful in removing the biofilms related to peri-implantitis. The findings imply the need for further studies to develop more effective antimicrobial treatment procedures.

Isothermal Microcalorimetry Detects the Presence of Persister Cells in a Staphylococcus aureus Biofilm After Vancomycin Treatment

Staphylococcus aureus biofilm plays a major role in implant-associated infections. Here, the susceptibility of biofilm S. aureus to daptomycin, fosfomycin, vancomycin, trimethoprim/sulfamethoxazole, linezolid, and rifampicin was investigated by isothermal microcalorimetry (IMC). Moreover, the persister status of cells isolated from S. aureus biofilm after treatment with vancomycin was also analyzed. S. aureus biofilm was tolerant to all the antibiotics tested [minimum biofilm bactericidal concentration (MBBC) > 256 μg/ml], except to daptomycin [MBBC and minimum biofilm eradicating concentration (MBEC) = 32 μg/ml] and rifampin (MBBC and MBEC = 128 μg/ml). After the treatment of MRSA biofilm with 1024 μg/ml vancomycin, ∼5% cells survived, although metabolically inactive (persisters). Interestingly, IMC revealed that persister bacteria reverted to a normal-growing phenotype when inoculated into fresh medium without antibiotics. A staggered treatment of MRSA biofilm with vancomycin to kill all the metabolically active cells and daptomycin to kill persister cells eradicated the whole bacterial population. These results support the use in the clinical practice of a therapeutic regimen based on the use of two antibiotics to kill persister cells and eradicate MRSA biofilms. IMC represents a suitable technique to characterize in real-time the reversion from persister to metabolically-active cells.

Influence of the amplitude of different side-to-side toothbrushes on noncontact biofilm removal

OBJECTIVES

To investigate the impact of the lateral deflection of toothbrush bristles (amplitude) of three side-to-side toothbrushes for noncontact biofilm removal in an artificial interdental space model.

MATERIALS AND METHODS

A three-species biofilm (Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sanguinis) was formed in vitro on protein-coated titanium disks. A flow chamber system was combined with a static biofilm growth model. The amplitudes of three commercial side-to-side toothbrushes were evaluated by means of a dose response analysis. The amplitudes were decreased in steps (100%, 85%, 70%, 55%, and 40%). Subsequently, the biofilm-coated substrates were exposed to the toothbrushes. The biofilms were analyzed with confocal laser scanning microscope images and measured using volumetric analyses.

RESULTS

The predictability of interdental biofilm reduction differed among the toothbrushes. A lower variety in the results of repeated experiments occurred in toothbrush C compared to toothbrushes A and B. Toothbrush C obtained highest percentage of biofilm reduction by 85% of amplitude power setting (median biofilm reduction 76%). Decreasing the amplitude from 85 to 40% resulted in reduced biofilm reduction (p = 0.029). In contrast, no significance could be observed for the differences of the tested amplitudes within toothbrushes A and B (p > 0.05). Between the toothbrushes, a significant difference in interdental biofilm reduction was found between C-A (p = 0.029) and C-B (p = 0.029) with amplitude of 85%.

CONCLUSIONS

The amplitude of one of the investigated side-to-side toothbrushes affected the biofilm reduction predictably in an interdental space model.

CLINICAL RELEVANCE

Within certain toothbrushes, a specific amplitude power setting may demonstrate beneficial effects on noncontact biofilm removal.

Development and characterization of an oral multispecies biofilm implant flow chamber model

Peri-implant infections are the most common cause of implant failure in modern dental implantology. These are caused by the formation of biofilms on the implant surface and consist of oral commensal and pathogenic bacteria, which harm adjacent soft and hard tissues and may ultimately lead to implant loss. In order to improve the clinical situation, there has to be a better understanding of biofilm formation on abiotic surfaces. Therefore, we successfully developed a system to cultivate an oral multispecies biofilm model in a flow chamber system, optimized for the evaluation of biofilm formation on solid materials by direct microscopic investigation. The model contains four relevant oral bacterial species: Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis in ratios similar to the native situation. The reliability of the developed “Hanoverian Oral Multispecies Biofilm Implant Flow Chamber” (HOBIC) model was verified. Biofilm volume and live/dead distribution within biofilms were determined by fluorescence staining and confocal laser scanning microcopy (CLSM). The individual species distribution was analyzed using quantitative real time PCR with propidium monoazide pretreatment (PMA-qRT-PCR) and by urea-NaCl fluorescence in situ hybridization (urea-NaCl-FISH). This in vitro model may be used to analyze biofilm formation on dental implants in more detail and to develop future implant systems with improved material properties.

The effect of metronidazole plus amoxicillin or metronidazole plus penicillin V on periodontal pathogens in an in vitro biofilm model

A combination of metronidazole (MET) and amoxicillin (AMX) is commonly used as adjunct to mechanical therapy of periodontal disease. The use of broad spectrum antibiotics such as AMX may contribute to development of antibiotic resistance. The aim was to evaluate the in vitro effect of replacing AMX with penicillin V (PV) in combination with MET on a biofilm model. A biofilm model consisting of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Fusobacterium nucleatum was developed. The biofilms were exposed to AMX + MET and PV + MET in two different concentrations. Bacterial viability in biofilms following antibiotic exposure was assessed by viable counts and by confocal microscopy. No live colonies of P. gingivalis nor F. nucleatum were retrieved from biofilms exposed to AMX + MET or PV + MET. The amount of A. actinomycetemcomitans was 4-5 logs reduced following antibiotic treatment; no statistical significance was achieved between AMX + MET or PV + MET treated biofilms. Replacement of AMX with PV at the same concentration, in combination with MET, resulted in similar effect on bacterial viability in this in vitro model. The option of using PV + MET instead of AMX + MET deserves further investigation, as this may contribute to reduce the risk of antibiotic resistance development.

The antimicrobial activity of ephedrine and admixture of ephedrine and propofol: an in vitro study

Introduction

Propofol and Ephedrine are commonly used during anesthesia maintenance, the former as a hypnotic agent and the later as a vasopressor. The addition of propofol to ephedrine or administration of ephedrine before propofol injection is useful for decreasing or preventing propofol related hemodynamic changes and vascular pain. This in vitro study evaluated the antibacterial effect on common hospital-acquired infection pathogens of ephedrine alone or combined with propofol.

Material and method

The study was performed in two stages. In the first, the Minimum Inhibitory Concentration of propofol and ephedrine alone and combined was calculated for Escherichia coli, Enterococcus faecium, Staphylococcus aureus, Pseudomonas aeruginosa, and a clinical isolate of Acinetobacter spp. at 0, 6, 12 and 24 h, using the microdilution method. In the second stage, the same drugs and combination were used to determine their effect on bacterial growth. Bacterial solutions were prepared at 0.5 MacFarland in sterile 0.9% physiological saline and diluted at 1/100 concentration. Colony numbers were measured as colony forming units.mL⁻¹ at 0, 2, 4, 6, 8, 10 and 12th hours.

Results

Ephedrine either alone or combined with propofol did not have an antimicrobial effect on Escherichia coli, Enterococcus faecium, or Pseudomonas aeruginosa and this was similar to propofol. However, ephedrine alone and combined with propofol was found to have an antimicrobial effect on Staphylococcus aureus and Acinetobacter species at 512 mcg.mL⁻¹ concentration and significantly decreased bacterial growth rate.

Conclusion

Ephedrine has an antimicrobial activity on Staphylococcus aureus and Acinetobacter species which were frequently encountered pathogens as a cause of nosocomial infections.

Efficacy of various side-to-side toothbrushes and impact of brushing parameters on noncontact biofilm removal in an interdental space model

OBJECTIVES

The objective of this study was to evaluate the efficacy of four different side-to-side toothbrushes and the impact of various brushing parameters on noncontact biofilm removal in an adjustable interdental space model.

MATERIALS AND METHODS

A three-species biofilm, consisting of Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus sanguinis, was formed in vitro on protein-coated titanium disks using a flow chamber combined with a static biofilm growth model. Subsequently, the biofilm-coated disks were exposed to four different powered toothbrushes (A, B, C, D). The parameters distance (0 and 1 mm), brushing time (2, 4, and 6 s), interdental space width (1, 2, and 3 mm), and toothbrush angulation (45° and 90°) were tested. The biofilm volumes were determined using volumetric analyses with confocal laser scanning microscope (Zeiss LSM700) images and Imaris version 7.7.2 software.

RESULTS

The median percentages of simulated interdental biofilm reduction by the tested toothbrushes ranged from 7 to 64 %. The abilities of the analyzed toothbrushes to reduce the in vitro biofilm differed significantly (p < 0.05). Three of the tested toothbrushes (A, B, C) were able to significantly reduce a simulated interdental biofilm by noncontact brushing (p ≤ 0.005). The brushing parameters and their combinations tested in the experiments revealed only minor effects on in vitro interdental biofilm reduction (p > 0.05).

CONCLUSIONS

A three-species in vitro biofilm could be altered by noncontact brushing with toothbrushes A, B, and C in an artificial interdental space model.

CLINICAL RELEVANCE

Certain side-to-side toothbrushes demonstrate in vitro a high efficacy in interdental biofilm removal without bristle-to-biofilm contact.

Development of novel electrospun dual-drug fiber mats loaded with a combination of ampicillin and metronidazole

OBJECTIVE

Our study was performed with the aim of preparing electrospun polylactide fibers with a combination of ampicillin (AMP) and metronidazole (MNZ) and investigating their drug release behavior and the antibacterial effect on Aggregatibacter actinomycetemcomitans and other oral pathogens.

METHODS

AMP and MNZ were integrated as a combination in two separate fibers (dual fiber mats - DFW mix) of electrospun PLA fiber mats by means of multijet electrospinning and in a single fiber (single fiber mats - SFW mix). HPLC (high-performance liquid chromatography) was used to measure the released drug quantities. Agar diffusion tests were used to determine the antibacterial effect of the eluates on A. actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis and Enterococcus faecalis. The neutral red test was made to examine the cytocompatibility of the eluates with human gingival fibroblasts (hGFs).

RESULTS

The release of the active agents varied with the antibiotic concentrations initially used in the fiber mats, but also with the distribution of the active agents in one or two fibers. Of the total quantity of MNZ (AMP), the SFW mix fiber mats released >60% (>70%) within a span of 5min, and 76% (71%) after 96h. With these drug concentrations released by the fiber mats (≥5m%), an antibacterial effect was achieved on A. actinomycetemcomitans and on all other species tested. Fiber mats and their eluates have no cytotoxic influence on human gingival fibroblasts (hGFs).

SIGNIFICANCE

Electrospun AMP/MNZ-loaded polymer fibers are a potential drug delivery system for use in periodontal and endodontic infections.

Accuracy of commercial kits and published primer pairs for the detection of periodontopathogens

OBJECTIVES

Despite the input of microbiome research, a group of 20 bacteria continues to be the focus of periodontal diagnostics and therapy. The aim of this study was to compare three commercial kits and laboratory-developed primer pairs for effectiveness in detecting such periodontopathogens.

MATERIALS AND METHODS

Fourteen bacterial mock communities, consisting of 16 randomly assembled bacterial strains, were used as reference standard for testing kits and primers. Extracted DNA from mock communities was analyzed by PCR in-house with specific primers and forwarded for analysis to the manufacturer's laboratory of each of the following kits: ParoCheck®Kit 20, micro-IDent®plus11, and Carpegen® Perio Diagnostik.

RESULTS

The kits accurately detected Fusobacterium nucleatum, Prevotella intermedia/Prevotella nigrescens, Parvimonas micra, Aggregatibacter actinomycetemcomitans, Campylobacter rectus/showae, Streptococcus mitis, Streptococcus mutans, and Veillonella parvula. The in-house primers for F.nucleatum were highly specific to subtypes of the respective periopathogen. Other primers repeatedly detected oral pathogens not present in the mock communities, indicating reduced specificity.

CONCLUSIONS

The commercial kits used in this study are reliable tools to support periodontal diagnostics. Whereas the detection profile of the kits is fixed at a general specificity level, the design of primers can be adjusted to differentiate between highly specific strains. In-house primers are more error-prone. Bacterial mock communities can be established as a reference standard for any similar testing.

CLINICAL RELEVANCE

The tested kits render good results with selected bacterial species. Primers appear to be less useful for routine clinical diagnostics and of limited applicability in research. Basic information about the periodontopathogens identified in this study supports clinical decision-making.

Determinants of biofilm formation and cleanability of titanium surfaces

OBJECTIVE

The aim of the present study was to analyze biofilm formation on four different titanium-based surfaces (machined titanium zirconium (TiZr) alloy, M; machined, acid-etched TiZr alloy, modMA; machined, sandblasted, acid-etched TiZr alloy, modSLA; and micro-grooved titanium aluminum vanadium alloy, TAV MG) in an experimental human model.

MATERIAL AND METHODS

Custom-made discs were mounted in individual intraoral splint housings and worn by 16 volunteers for 24 h. The safranin staining assay, isothermal microcalorimetry (IMC), and SEM were applied before and after surface cleaning.

RESULTS

The hydrophilic surfaces modMA and modSLA with greater surface micro-roughness exhibited significantly more biofilm than the hydrophobic surfaces TAV MG and M. The standardized cleaning procedure substantially reduced the biofilm mass on all surfaces. After cleaning, the IMC analyses demonstrated a longer lag time of the growth curve on TAV MG compared to modSLA. Inter- and intraindividual variations in biofilm formation on the titanium discs were evident throughout the study.

CONCLUSIONS

Surface hydrophilicity and roughness enhanced biofilm formation in vivo, whereas surface topography was the most influential factor that determined surface cleanability. While the grooved surface retained larger amounts of initial biofilm, the machined surface was easier to clean, but proliferation indicated by increased metabolic activity (growth rate) in IMC occurred despite mechanical biofilm removal.

Non-surgical periodontal therapy supplemented with systemically administered azithromycin: a systematic review of RCTs

BACKGROUND

Azithromycin may be an alternative adjunctive systemic antibiotic in non-surgical periodontal therapy.

OBJECTIVE

This study aims to identify randomized controlled trials evaluating non-surgical periodontal treatment of chronic and/or aggressive periodontitis supplemented with systemically administered azithromycin.

MATERIALS AND METHODS

A systematic literature search was performed for publications published by 31 March 2014 using electronic databases and hand search. Randomized controlled trials published in English or German language, with a follow-up ≥6 months were included. From 231 titles identified, nine publications were eligible for inclusion.

RESULTS

Among the studies included, showing some risk of bias, seven reported on patients with chronic periodontitis and two with aggressive periodontitis. Minor adverse events were described in five studies. A synthesis of results using a vote counting method was applied. Significant (p < 0.05) beneficial effects of azithromycin were shown in six studies for probing depth changes and in five studies for clinical attachment level changes.

CONCLUSION

In contrast to aggressive periodontitis patients, data from this analysis indicate a potential benefit of systemic azithromycin as adjunctive to non-surgical periodontal therapy in chronic periodontitis patients.

CLINICAL RELEVANCE

When contraindications for the standard antibiotics are present, azithromycin (AZM) may be considered as alternative systemically administered antibiotic drug in selected cases of chronic periodontitis.

Health, Maintenance, and Recovery of Soft Tissues around Implants

BACKGROUND

The health of peri-implant soft tissues is one of the most important aspects of osseointegration necessary for the long-term survival of dental implants.

PURPOSE

To review the process of soft tissue healing around osseointegrated implants and discuss the maintenance requirements as well as the possible short-comings of peri-implant soft tissue integration.

MATERIALS AND METHODS

Literature search on the process involved in osseointegration, soft tissue healing and currently available treatment modalities was performed and a brief description of each process was provided.

RESULTS

The peri-implant interface has been shown to be less effective than natural teeth in resisting bacterial invasion because gingival fiber alignment and reduced vascular supply make it more vulnerable to subsequent peri-implant disease and future bone loss around implants. And we summarized common procedures which have been shown to be effective in preventing peri-implantitis disease progression as well as clinical techniques utilized to regenerate soft tissues with bone loss in advanced cases of peri-implantitis.

CONCLUSION

Due to the difference between peri-implant interface and natural teeth, clinicians and patients should pay more attention in the maintenance and recovery of soft tissues around implants.

Development of a flow system for studying biofilm formation on medical devices with microcalorimetry

Isothermal microcalorimetry (IMC) is particularly suited to the study of microbiological samples in complex or heterogeneous environments because it does not require optical clarity of the sample and can detect metabolic activity from as few as 10(4) CFU/mL cells. While the use of IMC for studying planktonic cultures is well established, in the clinical environment bacteria are most likely to be present as biofilms. Biofilm prevention and eradication present a number of challenges to designers and users of medical devices and implants, since bacteria in biofilm colonies are usually more resistant to antimicrobial agents. Analytical tools that facilitate investigation of biofilm formation are therefore extremely useful. While it is possible to study pre-prepared biofilms in closed ampoules, better correlation with in vivo behaviour can be achieved using a system in which the bacterial suspension is flowing. Here, we discuss the potential of flow microcalorimetry for studying biofilms and report the development of a simple flow system that can be housed in a microcalorimeter. The use of the flow system is demonstrated with biofilms of Staphylococcus aureus.

Definition, etiology, prevention and treatment of peri-implantitis--a review

Peri-implant inflammations represent serious diseases after dental implant treatment, which affect both the surrounding hard and soft tissue. Due to prevalence rates up to 56%, peri-implantitis can lead to the loss of the implant without multilateral prevention and therapy concepts. Specific continuous check-ups with evaluation and elimination of risk factors (e.g. smoking, systemic diseases and periodontitis) are effective precautions. In addition to aspects of osseointegration, type and structure of the implant surface are of importance. For the treatment of peri-implant disease various conservative and surgical approaches are available. Mucositis and moderate forms of peri-implantitis can obviously be treated effectively using conservative methods. These include the utilization of different manual ablations, laser-supported systems as well as photodynamic therapy, which may be extended by local or systemic antibiotics. It is possible to regain osseointegration. In cases with advanced peri-implantitis surgical therapies are more effective than conservative approaches. Depending on the configuration of the defects, resective surgery can be carried out for elimination of peri-implant lesions, whereas regenerative therapies may be applicable for defect filling. The cumulative interceptive supportive therapy (CIST) protocol serves as guidance for the treatment of the peri-implantitis. The aim of this review is to provide an overview about current data and to give advices regarding diagnosis, prevention and treatment of peri-implant disease for practitioners.