The Effect of Microcosm Biofilm Decontamination on Surface Topography, Chemistry, and Biocompatibility Dynamics of Implant Titanium Surfaces.

Since the inception of dental implants, a steadily increasing prevalence of peri-implantitis has been documented. Irrespective of the treatment protocol applied for the management of peri-implantitis, this biofilm-associated pathology, continues to be a clinical challenge yielding unpredictable and variable levels of resolution, and in some cases resulting in implant loss. This paper investigated the effect of microcosm biofilm in vitro decontamination on surface topography, wettability, chemistry, and biocompatibility, following decontamination protocols applied to previously infected implant titanium (Ti) surfaces, both micro-rough -Sandblasted, Large-grit, Acid-etched (SLA)-and smooth surfaces -Machined (M). Microcosm biofilms were grown on SLA and M Ti discs. These were treated with TiBrushes (TiB), combination of TiB and photodynamic therapy (PDT), combination of TiB and 0.2%CHX/1%NaClO, plus or minus Ultraviolet-C (UV-C) radiation. Surface topography was evaluated by Scanning Electron Microscopy (SEM) and Laser Surface Profilometry. Surface function was analysed through wettability analysis. Surface chemistry evaluation of the discs was performed under SEM/Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Biocompatibility was tested with the cytocompatibility assay using human osteoblast-like osteosarcoma cell line (MG-63) cells. Elemental analysis of the discs disclosed chemical surface alterations resulting from the different treatment modalities. Titanium, carbon, oxygen, sodium, aluminium, silver, were identified by EDX as the main components of all the discs. Based on the data drawn from this study, we have shown that following the decontamination of Ti surfaces the biomaterial surface chemistry and topography was altered. The type of treatment and Ti surface had a significant effect on cytocompatibility (p = 0.0001). Although, no treatment modality hindered the titanium surface biocompatibility, parameters such as the use of chemical agents and micro-rough surfaces had a higher cytotoxic effect in MG-63 cells. The use of smooth surfaces, and photofunctionalisation of the TiO2 layer had a beneficial effect on cytocompatibility following decontamination.

Differences in the subgingival microbial population of chronic periodontitis in subjects with and without type 2 diabetes mellitus-a systematic review.

OBJECTIVES: The purpose of this systematic review was to evaluate the available evidence in the literature in regard to the subgingival microbial population of chronic periodontitis in subjects with type 2 diabetes mellitus (T2DM+PD) compared to non-diabetic subjects (NDM+PD). MATERIALS AND METHODS: A literature search was conducted at Ovid MEDLINE and EMBASE database from 1980 to 2016, supplemented by hand searching as needed. Studies presenting with at least one of the primary outcomes (presence of any subgingival microorganisms, proportion and/or the amount of any subgingival plaque bacteria in T2DM+PD versus NDM+PD) were included. Screening, data extraction and quality assessment were conducted independently and in duplicate. RESULTS: From 611 citations, 19 full-text papers were screened and 11 articles were included for critical appraisal by both reviewers. Some evidence of a difference in the microbial profile between chronic PD subjects with and without T2DM was identified. The strength of evidence is strongest in Tannerella forthysia (T .forsythia) which was reported to be less frequent in the diabetic (T2DM+PD) group in five of the studies, followed by a weaker strength of evidence for other periodontal pathogens such as Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), which were also found less frequent in the diabetic (T2DM+PD) group . CONCLUSION: Only few studies have compared T2DM+PD with NDM+PD. It is therefore strongly recommended that further studies which include four distinct groups of participants (NDM+PD, T2DM+PD, NDM+NPD, T2DM+NPD) instead of using intra-subject comparisons between healthy and diseased sites of the same subjects. CLINICAL RELEVANCE: Differences in bacterial populations of T2DM+PD in comparison to NDM+PD subjects may indicate the need of different protocols for the treatment of the diabetic patients with periodontal disease.

Oral Microcosm Biofilms Grown under Conditions Progressing from Peri-Implant Health, Peri-Implant Mucositis, and Peri-Implantitis.

Peri-implantitis is a disease influenced by dysbiotic microbial communities that play a role in the short- and long-term outcomes of its clinical treatment. The ecological triggers that establish the progression from peri-implant mucositis to peri-implantitis remain unknown. This investigation describes the development of a novel in vitro microcosm biofilm model. Biofilms were grown over 30 days over machined titanium discs in a constant depth film fermentor (CDFF), which was inoculated (I) with pooled human saliva. Following longitudinal biofilm sampling across peri-implant health (PH), peri-implant mucositis (PM), and peri-implantitis (PI) conditions, the characterisation of the biofilms was performed. The biofilm analyses included imaging by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), selective and non-selective culture media of viable biofilms, and 16S rRNA gene amplification and sequencing. Bacterial qualitative shifts were observed by CLSM and SEM across conditions, which were defined by characteristic phenotypes. A total of 9 phyla, 83 genera, and 156 species were identified throughout the experiment. The phyla Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Actinobacteria showed the highest prevalence in PI conditions. This novel in vitro microcosm model provides a high-throughput alternative for growing microcosm biofilms resembling an in vitro progression from PH-PM-PI conditions.

Drinking habits are associated with changes in the dental plaque microbial community.

Caries and gingivitis are the most prevalent oral infectious diseases of humans and are due to the accumulation of dental plaque (a microbial biofilm) on the tooth surface and at the gingival margin, respectively. Several in vitro and in vivo studies have shown that many natural components of foods and beverages inhibit the adhesion of and/or exert activity against oral bacteria. These biological activities have mainly been attributed to the polyphenol fraction. In order to explore the possibility that diet can alter the dental plaque community, in this study we evaluated the composition of the microbiota of supra- and subgingival plaque samples collected from 75 adult subjects with different drinking habits (drinkers of coffee, red wine, or water for at least 2 years) by analyzing the microbial population through the separation of PCR-amplified fragments using the denaturing gradient gel electrophoresis (DGGE) technique. The mean numbers of bands of the DGGE profiles from all three categories were evaluated. There were no significant differences between the two kinds of plaque collected from the control group (water drinkers), and this group showed the highest number of bands (supragingival plaque, 18.98 +/- 3.16 bands; subgingival plaque, 18.7 +/- 3.23 bands). The coffee and wine drinker groups generated the lowest numbers of bands for both supragingival plaque (coffee drinkers, 8.25 +/- 3.53 bands; wine drinkers, 7.93 +/- 2.55 bands) and subgingival plaque (coffee drinkers, 8.3 +/- 3.03 bands; wine drinkers, 7.65 +/- 1.68 bands). The differences between coffee drinkers or wine drinkers and the control group (water drinkers) were statistically significant. A total of 34 microorganisms were identified, and the frequency of their distribution in the three subject categories was analyzed. A greater percentage of subjects were positive for facultative aerobes when supragingival plaque was analyzed, while anaerobes were more frequent in subgingival plaque samples. It is noteworthy that the frequency of identification of anaerobes was significantly reduced when the frequencies for coffee and wine drinkers were compared with the frequencies for subjects in the control group. The DGGE profiles of the organisms in both plaque samples from all groups were generated and were used to construct dendrograms. A number of distinct clusters of organisms from water, coffee, and wine drinkers were formed. The clustering of some of the DGGE results into cohort-specific clusters implies similarities in the microbiotas within these groups and relevant differences in the microbiotas between cohorts. This supports the notion that the drinking habits of the subjects may influence the microbiota at both the supragingival and the subgingival levels.

Probing the nanoadhesion of Streptococcus sanguinis to titanium implant surfaces by atomic force microscopy.

As titanium (Ti) continues to be utilized in great extent for the fabrication of artificial implants, it is important to understand the crucial bacterium-Ti interaction occurring during the initial phases of biofilm formation. By employing a single-cell force spectroscopy technique, the nanoadhesive interactions between the early-colonizing Streptococcus sanguinis and a clinically analogous smooth Ti substrate were explored. Mean adhesion forces between S. sanguinis and Ti were found to be 0.32±0.00, 1.07±0.06, and 4.85±0.56 nN for 0, 1, and 60 seconds contact times, respectively; while adhesion work values were reported at 19.28±2.38, 104.60±7.02, and 1,317.26±197.69 aJ for 0, 1, and 60 seconds, respectively. At 60 seconds surface delays, minor-rupture events were modeled with the worm-like chain model yielding an average contour length of 668±12 nm. The mean force for S. sanguinis minor-detachment events was 1.84±0.64 nN, and Poisson analysis decoupled this value into a short-range force component of -1.60±0.34 nN and a long-range force component of -0.55±0.47 nN. Furthermore, a solution of 2 mg/mL chlorhexidine was found to increase adhesion between the bacterial probe and substrate. Overall, single-cell force spectroscopy of living S. sanguinis cells proved to be a reliable way to characterize early-bacterial adhesion onto machined Ti implant surfaces at the nanoscale.

Development of remineralizing, antibacterial dental materials.

Light curable methacrylate dental monomers containing reactive calcium phosphate filler (monocalcium phosphate monohydrate (MCPM) with particle diameter of 29 or 90microm) and beta-tricalcium phosphate (beta-TCP) at 1:1 weight ratio in a powder:liquid ratio (PLR) of 1:1 or 3:1 and chlorhexidine diacetate (0 or 5 wt.%), were investigated. Upon light exposure, approximately 90% monomer conversion was gained irrespective of the formulation. Increasing the PLR promoted water sorption by the set material, induced expansion and enhanced calcium, phosphate and chlorhexidine release. Concomitantly, a decline in compressive and biaxial flexural strengths occurred. With a reduction in MCPM particle diameter, however, calcium and phosphate release was reduced and less deterioration in strength observed. After 24h, the remaining MCPM had reacted with water and beta-TCP, forming, within the set materials, brushite of lower solubility. This provided a novel means to control water sorption, component release and strength properties. Measurable chlorhexidine release was observed for 6weeks. Both diffusion rate and total percentage of chlorhexidine release decreased with lowering PLR or by adding buffer to the storage solutions. Higher chlorhexidine release was associated with reduced bacterial growth on agar plates and in a biofilm fermenter. In cell growth media, brushite and hydroxyapatite crystals precipitated on the composite material surfaces. Cells spread on both these crystals and the exposed polymer composite surfaces, indicating their cell compatibility. These formulations could be suitable antibacterial, biocompatible and remineralizing dental adhesives/liners.