Identification of Enterococcus Faecalis and Pseudomonas Aeruginosa on and in Implants in Individuals with Peri-implant Disease: A Cross-Sectional Study

PURPOSE

To verify whether the parts of dental implants can be contaminated by opportunistic pathogens.

MATERIALS AND METHODS

In this cross-sectional study, 38 individuals (52 implants) were investigated. Samples for microbiologic analysis (for a total of 180 sites) were obtained from each individual, from three types of sites in the following order: (1) the peri-implant sulcus of each implant, (2) the gingival sulcus of adjacent teeth, and (3) inside the implant-abutment connection and the abutment of each implant. Swabs from the oral mucosa (cheeks, tongue, and pharynx) were also collected. Quantitative real-time polymerase chain reaction was carried out for total bacterial counts of Enterococcus faecalis and Pseudomonas aeruginosa. Two-way analysis of variance (sites, species) and Holm-Sidak tests were used for statistical analyses.

RESULTS

No opportunistic bacteria were found in the gingival sulcus specimens (38 sites). E faecalis was detected in the peri-implant sulcus (3 of 52 sites) and the inner connection/abutment portion (3 of 52 sites). P aeruginosa was identified only in the oral mucosa swabs (1 of 38 sites) and represented the highest bacterial number (3.5 × 10⁶). Statistically significant differences were only found between species and in the peri-implant sulcus.

CONCLUSION

Within the limitations of this study, significant differences in the presence and levels of nosocomial bacteria were detected in the peri-implant environment of diseased implants. From a clinical point of view, data from this study might suggest that, in patients affected by peri-implantitis, prostheses should be removed and the implant-abutment connection disinfected routinely, along with implant surface decontamination.

Histomorphometric Analysis of Contaminated Autogenous Tooth Graft Materials After Various Sterilization

PURPOSE

The purpose of this study was to evaluate histomorphometrically contaminated autogenous tooth graft materials, which were resterilized.

MATERIALS AND METHODS

The intentional defects (diameter: 8 mm, depth: 4 mm) were formed around implant fixture on the iliac crest of 6 mongrel dogs. Autogenous tooth graft materials were made by extracted premolars. After the contamination of the tooth materials, graft procedure was performed; no contaminated group (control group), contaminated groups (nonsterilization group [group 1], ethylene oxide [EO] gas group [group 2], and autoclave group [group 3]). The bone-to-implant contact (BIC) and the new bone formation rate (NBFR) were evaluated after sacrifice.

RESULTS

The BIC and NBFR of groups 1 and 3 were significantly lower than the control group after 4 weeks. The BIC and NBRF of group 3 were significantly lower than the control group after 8 weeks. However, the BIC and NBRF of group 2 was not significantly different comparing with the control group after 4 and 8 weeks.

CONCLUSION

Sterilization using EO gas may be more favorable than high-pressure sterilization in cases the reuse of contaminated autogenous tooth graft materials.

Titanium Surface Priming with Phase-Transited Lysozyme to Establish a Silver Nanoparticle-Loaded Chitosan/Hyaluronic Acid Antibacterial Multilayer via Layer-by-Layer Self-Assembly

Objectives

The formation of biofilm around implants, which is induced by immediate bacterial colonization after installation, is the primary cause of post-operation infection. Initial surface modification is usually required to incorporate antibacterial agents on titanium (Ti) surfaces to inhibit biofilm formation. However, simple and effective priming methods are still lacking for the development of an initial functional layer as a base for subsequent coatings on titanium surfaces. The purpose of our work was to establish a novel initial layer on Ti surfaces using phase-transited lysozyme (PTL), on which multilayer coatings can incorporate silver nanoparticles (AgNP) using chitosan (CS) and hyaluronic acid (HA) via a layer-by-layer (LbL) self-assembly technique.

Methods

In this study, the surfaces of Ti substrates were primed by dipping into a mixture of lysozyme and tris(2-carboxyethyl)phosphine (TCEP) to obtain PTL-functionalized Ti substrates. The subsequent alternating coatings of HA and chitosan loaded with AgNP onto the precursor layer of PTL were carried out via LbL self-assembly to construct multilayer coatings on Ti substrates.

Results

The results of SEM and XPS indicated that the necklace-like PTL and self-assembled multilayer were successfully immobilized on the Ti substrates. The multilayer coatings loaded with AgNP can kill planktonic and adherent bacteria to 100% during the first 4 days. The antibacterial efficacy of the samples against planktonic and adherent bacteria achieved 65%-90% after 14 days. The sustained release of Ag over 14 days can prevent bacterial invasion until mucosa healing. Although the AgNP-containing structure showed some cytotoxicity, the toxicity can be reduced by controlling the Ag release rate and concentration.

Conclusions

The PTL priming method provides a promising strategy for fabricating long-term antibacterial multilayer coatings on titanium surfaces via the LbL self-assembly technique, which is effective in preventing implant-associated infections in the early stage.

Evaluation of resistance against bacterial microleakage of a new conical implant-abutment connection versus conventional connections: an in vitro study

The aim of the present in vitro study was to evaluate bacterial microleakage from inside to outside the implant-abutment assembly in a new design of internal conical connection compared to eight different internal connections. The design of this connection should prevent or limit microbiologic leakage into the surrounding implant tissue, that could contribute to infections without bone loss (mucositis) or with bone loss (peri-implantits). In order to investigate bacterial microleakage, the inner part of each system was inoculated with an Escherichia coli suspension. Eight different groups were considered; each group was composed of 10 dental implants, for a total of 80 implants. Groups 1-7 were considered controls, while group 8 was the test connection (an internal connection characterized by a double taper principle). Results showed that in control implants (Group 1 to 7), little microleakage was observed after the first 6 hours (500 CFU/ μl) and, after 24 hours of incubation, they showed a significant bacterial contamination in all samples (>100.000 CFU/ μl). In group 8 (test connection) no contamination was found in the first 6 hours, with 7 out of 10 implants showing no contamination even after 96 hours. Statistically significant differences were found between Group 8 and the other groups (p<0.05), whereas no significant differences were found among implants of the control groups (from group 1 to 7). Within the limits of the present study, the new connection studied presented significantly less microleakage at 96 h in comparison with the other control internal connections.

Antibacterial Peptide-Based Gel for Prevention of Medical Implanted-Device Infection

Implanted medical devices are prone to infection. Designing new strategies to reduce infection and implant rejection are an important challenge for modern medicine. To this end, in the last few years many hydrogels have been designed as matrices for antimicrobial molecules destined to fight frequent infection found in moist environments like the oral cavity. In this study, two types of original hydrogels containing the antimicrobial peptide Cateslytin have been designed. The first hydrogel is based on alginate modified with catechol moieties (AC gel). The choice of these catechol functional groups which derive from mussel’s catechol originates from their strong adhesion properties on various surfaces. The second type of gel we tested is a mixture of alginate catechol and thiol-terminated Pluronic (AC/PlubisSH), a polymer derived from Pluronic, a well-known biocompatible polymer. This PlubisSH polymer has been chosen for its capacity to enhance the cohesion of the composition. These two gels offer new clinical uses, as they can be injected and jellify in a few minutes. Moreover, we show these gels strongly adhere to implant surfaces and gingiva. Once gelled, they demonstrate a high level of rheological properties and stability. In particular, the dissipative energy of the (AC/PlubisSH) gel detachment reaches a high value on gingiva (10 J.m^-2) and on titanium alloys (4 J.m^-2), conferring a strong mechanical barrier. Moreover, the Cateslytin peptide in hydrogels exhibited potent antimicrobial activities against P. gingivalis, where a strong inhibition of bacterial metabolic activity and viability was observed, indicating reduced virulence. Gel biocompatibility tests indicate no signs of toxicity. In conclusion, these new hydrogels could be ideal candidates in the prevention and/or management of periimplant diseases.

Antimicrobial effectiveness of cetylpyridinium chloride and zinc chloride-containing mouthrinses on bacteria of halitosis and peri-implant disease

PURPOSE

To clarify the antimicrobial efficacy of zinc chloride (ZnCl2) and cetylpyridinium chloride (CPC) by testing their impact on the growth of seven bacterial strains known to be involved in the pathophysiology of both peri-implant disease and halitosis-Staphylococcus aureus, Streptococcus mutans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Treponema denticola, and Tannerella forsythia.

MATERIALS AND METHODS

A time-response growth curve was obtained. Commercial mouthrinses with CPC, ZnCl2, or both were added to the media in a final concentration of 0.25% CPC, 2.5% ZnCl2, and 2.5% ZnCl2 with 0.25% CPC.

RESULTS

Both CPC and ZnCl2 effectively inhibited the growth of almost all bacterial strains tested except T denticola. ZnCl2 was generally more effective in suppressing bacterial growth than CPC. ZnCl2 with CPC showed the greatest inhibitory activities on almost all strains of bacterial growth except for P gingivalis and T denticola, followed by ZnCl2, then CPC, thus suggesting the possibility of a synergistic effect of the two agents. P gingivalis exhibited a different pattern because ZnCl2 showed the most significant inhibitory effect. CPC did not show growth inhibitory effects on T denticola, but ZnCl2 did.

CONCLUSION

Zinc and CPC effectively inhibit bacterial growth that causes both halitosis and peri-implant disease. The effect is even more powerful when applied in combination.

The Microbiologic Profile Associated with Peri-Implantitis in Humans: A Systematic Review

PURPOSE

To qualitatively investigate the microbiologic profile in peri-implantitis by systematically reviewing the published literature on peri-implant infection.

MATERIALS AND METHODS

Searches of the US National Institutes of Health free digital archives of the biomedical and life sciences journal literature (PubMed) and The Cochrane Library of the Cochrane Collaboration (CENTRAL), as well as a hand search of other literature, were conducted to identify articles potentially relevant for the review. Randomized clinical trials, prospective cohort studies, longitudinal studies, case-control studies, and cross-sectional studies in humans reporting microbiologic findings in patients with diagnosed peri-implantitis were considered eligible for this review. Screening, data extraction, and quality assessment were conducted independently and in duplicate.

RESULTS

Twenty-one articles were eligible for inclusion in this review. Early studies focused on the identification of target periopathogens, whereas more recent studies used advanced molecular techniques for comprehensive overview of the peri-implantitis-associated microbiome. In summary, the microbiologic profile in peri-implantitis (1) is complex and variable, (2) consists of gram-negative anaerobic periopathogens and opportunistic microorganisms in almost the same ratio, (3) is frequently associated with the Epstein-Barr virus and nonsaccharolytic anaerobic gram-positive rods, (4) is not so strictly associated with Staphylococcus aureus, and (5) is different from that of periodontitis. A meta-analysis could not be performed because of the heterogeneity of the reviewed studies.

CONCLUSION

Although a comparison of the published results was limited because of the inhomogeneity of the studies, it is clear that the microbiologic profile of peri-implantitis consists of aggressive and resistant microorganisms and is distinct from that of periodontitis. It seems that the quantitative characteristics of the microflora cohabitants represent the key determinant of disease, rather than the qualitative composition, which is very similar in healthy and peri-implantitis states.

Effect and treatment of lactobacillus on inflammation around the implant

Ultrasonic scaling and antibiotic therapy are traditional therapeutic methods for inflammation around the implant but therapeutic effect is not ideal. In view of maintaining flora balance around the implant and implant long-term solid holdup, this experiment observes impact and clinical effect of lactobacillus metabolite on inflammation around the impact to explore a new kind of ecological drug. This drug has little or no side effect, good curative effect and low recurrence rate, which can be applied for broad groups of people. 16 cases with inflammation around the impact were divided into experimental group and control group, 8 cases for each group. Lactobacillus metabolites gargle was offered to experimental group; purified water was offered to control group. Gargle way is 3 times/day, 20 ml/time, 3 min/time and for 7 days. Two groups of cases were clinical and microbiological tested before gargle, 3 days, 7 days and 30 days after gargle. Based on clinical and microbiological test of 8 cases of health implant, we observe sub gingival flora variation trend and clinical effects of infectors with inflammation around implant. Lactobacillus metabolite can improve clinical index of inflammation around the impact including MPLI, GI, MBI and PD. Lactobacillus metabolite has a strong treatment effect on inflammation around the implant and has no side effect.

Effect of UV-photofunctionalization on oral bacterial attachment and biofilm formation to titanium implant material

Bacterial biofilm infections remain prevalent reasons for implant failure. Dental implant placement occurs in the oral environment, which harbors a plethora of biofilm-forming bacteria. Due to its trans-mucosal placement, part of the implant structure is exposed to oral cavity and there is no effective measure to prevent bacterial attachment to implant materials. Here, we demonstrated that UV treatment of titanium immediately prior to use (photofunctionalization) affects the ability of human polymicrobial oral biofilm communities to colonize in the presence of salivary and blood components. UV-treatment of machined titanium transformed the surface from hydrophobic to superhydrophilic. UV-treated surfaces exhibited a significant reduction in bacterial attachment as well as subsequent biofilm formation compared to untreated ones, even though overall bacterial viability was not affected. The function of reducing bacterial colonization was maintained on UV-treated titanium that had been stored in a liquid environment before use. Denaturing gradient gel-electrophoresis (DGGE) and DNA sequencing analyses revealed that while bacterial community profiles appeared different between UV-treated and untreated titanium in the initial attachment phase, this difference vanished as biofilm formation progressed. Our findings confirm that UV-photofunctionalization of titanium has a strong potential to improve outcome of implant placement by creating and maintaining antimicrobial surfaces.

[Study of oral microbial adhesion and biofilm formation on the surface of nano-fluorohydroxyapatite/polyetheretherketone composite]

OBJECTIVE

To develop novel polyetheretherketone (PEEK) based nanocomposites which possess the favorable antibacterial property, and to investigate the oral microbial adhesion and biofilm formation on the surfaces of PEEK, nano-fluorohydroxyapatite (n-FHA)-PEEK and nano-hydroxyaptite (n-HA)-PEEK.

METHODS

The bacterial adhesion and biofilm formation on the surfaces of n-FHA-PEEK, n-HA-PEEK were investigated via microbial viability assay kit and laser scanning confocal microscope (LSCM), respectively, with pure PEEK as control group.

RESULTS

No significantly statistical difference were found in the bacterial adhesion amounts on the surfaces of n-FHA-PEEK, n-HA-PEEK and PEEK at 1 h and 4 h. However, the number of bacteria on the n-FHA-PEEK surface decreased dramatically at 2 h (0.496 ± 0.008) compared with n-HA-PEEK groups (0.543 ± 0.015, P < 0.01). Although the biofilms formation on surfaces observed by LSCM had similar morphology and thickness at 3, 7, 14 d, that on the n-FHA-PEEK surface showed the highest dead-to-live bacteria ratio among the three materials at 14 d.

CONCLUSIONS

The combination of n-HA, especially for the n-FHA could inhibit the bacteria adhesion and accelerate the bacterial death, eventually may have an influence on the structure of biofilms and reduce the risk of peri-implantitis. Therefore, n-FHA-PEEK nanocomposites presented a good prospect for clinical applications as dental implant materials.

Chlorhexidine hexametaphosphate nanoparticles as a novel antimicrobial coating for dental implants

Dental implants are an increasingly popular solution to missing teeth. Implants are prone to colonisation by pathogenic oral bacteria which can lead to inflammation, destruction of bone and ultimately implant failure. The aim of this study was to investigate the use of chlorhexidine (CHX) hexametaphosphate (HMP) nanoparticles (NPs) with a total CHX concentration equivalent to 5 mM as a coating for dental implants. The CHX HMP NPs had mean diameter 49 nm and composition was confirmed showing presence of both chlorine and phosphorus. The NPs formed micrometer-sized aggregated surface deposits on commercially pure grade II titanium substrates following immersion-coating for 30 s. When CHX HMP NP-coated titanium specimens were immersed in deionised water, sustained release of soluble CHX was observed, both in the absence and presence of a salivary pellicle, for the duration of the study (99 days) without reaching a plateau. Control specimens exposed to a solution of aqueous 25 µM CHX (equivalent to the residual aqueous CHX present with the NPs) did not exhibit CHX release. CHX HMP NP-coated surfaces exhibited antimicrobial efficacy against oral primary colonising bacterium Streptococcus gordonii within 8 h. The antimicrobial efficacy was greater in the presence of an acquired pellicle which is postulated to be due to retention of soluble CHX by the pellicle.

An in vivo comparison of internal bacterial colonization in two dental implant systems: identification of a pathogenic reservoir

OBJECTIVES

The aim of this study was to compare internal bacterial colonization in two implant systems, one screw root form (SRF) with an external hexagon connection and one plateau root form (PRF) with a Morse taper internal connection.

MATERIALS AND METHODS

Thirty-two implants; 12 SRF and 20 PRF, were sampled in 15 patients. All implants had been in function for at least 6 months prior to sampling. The implant restoration was removed and 10 µl of sterile saline was introduced into the implant well via a sterile glass syringe. The saline was drawn back up and transferred to the laboratory for microbiological analysis. The number of aerobic and anaerobic colony forming units per millilitre was determined and the dominant micro-organism in each sample was identified by 16s rRNA gene amplicon sequencing.

RESULTS

There was a significant difference between bleeding on probing around the SRF implants (3%) and the PRF implants (28%) (p = 0.0496). Bacterial colonization was identified at 11 SRF and 19 PRF implants. The numbers of anaerobic bacteria recovered from PRF implants was significantly higher than that from SRF implants (p = 0.0002). Streptococcus species and Enterococcus faecalis were found to dominate.

CONCLUSIONS

This in vivo study demonstrated bacterial colonization in both types of implant systems, irrespective of the type of connection. Significantly greater anaerobic counts were found in the Morse taper internal connection implants.

How do peri-implant mucositis and gingivitis respond to supragingival biofilm control - an intra-individual longitudinal cohort study

PURPOSE

This single-arm study to compare the gingival with peri-implant mucosal inflammatory response to a mechanical supragingival-supramucosal biofilm control program.

MATERIALS AND METHODS

Twenty-two participants (55.7 ± 11.2 years) with both gingivitis and periimplant mucositis were examined at days 0, 30 and 390 (full mouth/6 sites per tooth/implant [TTH/IMPL]) for visible plaque (VPI), gingival bleeding (GBI), modified plaque (mPlI) and bleeding indexes (mBI), probing depth (PD) and bleeding on probing (BOP). The biofilm control was carried out weekly in the first month and every 3 months thereafter. An intention-to-treat analysis was performed (drop-out rate = 8) and linear models were used against comparisons in order to look at the clustering of TTH/IMPL by each individual.

RESULTS

VPI/mPlI and GBI/mBI reduced from day 0 onwards. Intra-group reductions (P < 0.05) were observed at day 30. PD values (in mm) were higher (P < 0.001) for IMPL than for TTH [mean difference (95% CI) at day 0: -1.10 (-1.58 to -0.63); day 30: -0.88 (-1.28 to -0.48); and day 390: -0.60 (-0.84 to -0.33)], where both groups showed reductions (P < 0.05) throughout the study. BOP was greater (P = 0.00001) for IMPL at baseline [mean difference (95% CI): -0.24 (-0.31 to -0.17)] but reduced (P = 0.00001) and showed similar levels to TTH from day 30 onwards. With regard to sites with the greatest PD, BOP reduced (P < 0.05) in both IMPL and TTH, with greater PD reductions observed for IMPL (P = 0.00001).

CONCLUSIONS

The supragingival-supramucosal biofilm control benefited both teeth and implants.

Significance of biofilms in dentistry

In the past decades significant scientific progress has taken place in the knowledge about biofilms. They constitute multilayer conglomerates of bacteria and fungi, surrounded by carbohydrates which they produce, as well as substances derived from saliva and gingival fluid. Modern techniques showed significant diversity of the biofilm environment and a system of microbial communication (quorum sensing), enhancing their survival. At present it is believed that the majority of infections, particularly chronic with exacerbations, are a result of biofilm formation, particularly in the presence of biomaterials. It should be emphasised that penetration of antibiotics and other antimicrobial agents into deeper layers of a biofilm is poor, causing therapeutic problems and necessitating sometimes removal of the implant or prosthesis. Biofilms play an increasing role in dentistry as a result of more and more broad use in dental practice of plastic and implantable materials. Biofilms are produced on the surfaces of teeth as dental plaque, in the para-nasal sinuses, on prostheses, dental implants, as well as in waterlines of a dental unit, constituting a particular risk for severely immunocompromised patients. New methods of therapy and prevention of infections linked to biofilms are under development.

Pyrosequencing of supra- and subgingival biofilms from inflamed peri-implant and periodontal sites

BACKGROUND

To investigate the microbial composition of biofilms at inflamed peri-implant and periodontal tissues in the same subject, using 16S rRNA sequencing.

METHODS

Supra- and submucosal, and supra- and subgingival plaque samples were collected from 7 subjects suffering from diseased peri-implant and periodontal tissues. Bacterial DNA was isolated and 16S rRNA genes were amplified, sequenced and aligned for the identification of bacterial genera.

RESULTS

43734 chimera-depleted, denoised sequences were identified, corresponding to 1 phylum, 8 classes, 10 orders, 44 families and 150 genera. The most abundant families or genera found in supramucosal or supragingival plaque were Streptoccocaceae, Rothia and Porphyromonas. In submucosal plaque, the most abundant family or genera found were Rothia, Streptococcaceae and Porphyromonas on implants. The most abundant subgingival bacteria on teeth were Prevotella, Streptococcaceae, and TG5. The number of sequences found for the genera Tannerella and Aggregatibacter on implants differed significantly between supra- and submucosal locations before multiple testing. The analyses demonstrated no significant differences between microbiomes on implants and teeth in supra- or submucosal and supra- or subgingival biofilms.

CONCLUSION

Diseased peri-implant and periodontal tissues in the same subject share similiar bacterial genera and based on the analysis of taxa on a genus level biofilm compositions may not account for the potentially distinct pathologies at implants or teeth.

In vivo effectiveness of silicone gel sheets as barriers at the inner microgap between a prosthetic abutment and an external-hexagon implant platform

PURPOSE

Bacterial penetration and colonization of the microgap at the implant-abutment interface have been reported in several studies. The aim of this study was to evaluate the effectiveness of placing a silicone membrane between the abutment and the implant platform in an attempt to seal the interface.

MATERIALS AND METHODS

A total of 15 external-hex implants were placed in 10 patients with clinically healthy peri-implant tissues, and all of the patients had ceramic prosthetic crowns. Samples were collected from the microgaps before, 30 days after, and 90 days after insertion of a silicone membrane. Bacterial DNA was extracted and submitted in triplicate to polymerase chain reaction using primers specific for four peri-implant pathogens: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia.

RESULTS

In the initial samples, a positivity of 52% was found, which was different from that found in samples collected after 30 days (32%) and 90 days (27%) after insertion of the membrane.

CONCLUSION

It was evident that the silicone membrane reduced, but did not prevent, penetration of these species into external-hex implants.

Occult peri-implant oroantral fistulae: posterior maxillary peri-implantitis/sinusitis of zygomatic or dental implant origin. Treatment and prevention with bone morphogenetic protein-2/absorbable collagen sponge sinus grafting

Sinus floor grafting with bone morphogenetic protein-2 for transsinus implant placement or as a salvage technique for sinus-involved peri-implantitis has been found to be successful. Transsinus implants for All-on-Four treatment, zygomatic implants including quad zygomatics, and infected transsinus implants underwent peri-implant grafting, which was found to seal off the sinus cavity from the oral cavity in an effort to prevent or treat sinusitis/peri-implantitis.

Analysis of bacterial flora associated with peri-implantitis using obligate anaerobic culture technique and 16S rDNA gene sequence

PURPOSE

To analyze and characterize the predominant bacterial flora associated with peri-implantitis by using culture techniques under obligate anaerobic conditions and 16S rDNA gene sequences.

MATERIALS AND METHODS

Subgingival bacterial specimens were taken from 30 patients: control (n = 15), consisting of patients with only healthy implants; and test (n = 15), consisting of patients with peri-implantitis. In both groups, subgingival bacterial specimens were taken from the deepest sites. An anaerobic glove box system was used to cultivate bacterial strains. The bacterial strains were identified by 16S rDNA genebased polymerase chain reaction and comparison of the gene sequences.

RESULTS

Peri-implantitis sites had approximately 10-fold higher mean colony forming units (per milliliter) than healthy implant sites. A total of 69 different bacterial species were identified in the peri-implantitis sites and 53 in the healthy implant sites. The predominant bacterial species in the peri-implantitis sites were Eubacterium nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, Parascardovia denticolens, Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis, Centipeda periodontii, and Parvimonas micra. The predominant bacteria in healthy implant sites apart from Streptococcus were Pseudoramibacter alactolyticus, Veillonella species, Actinomyces israelii, Actinomyces species, Propionibacterium acnes, and Parvimonas micra.

CONCLUSION

These results suggest that the environment in the depths of the sulcus showing peri-implantitis is well suited for growth of obligate anaerobic bacteria. The present study demonstrated that the sulcus around oral implants with peri-implantitis harbors high levels of asaccharolytic anaerobic gram-positive rods (AAGPRs) such as E. nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, and gram-negative anaerobic rods, suggesting that conventional periodontopathic bacteria are not the only periodontal pathogens active in peri-implantitis, and that AAGPRs may also play an important role.

Zwitterionic-based stainless steel with well-defined polysulfobetaine brushes for general bioadhesive control

Stainless steels are widely used as orthopaedic and dental implant; however, bioadhesion in the case of thrombosis, inflammation, and infection is one of their major limitations. One way to tackle this problem is to graft the stainless steel surface with a zwitterionic polymer known for being anti-bioadhesive. Controlled atom transfer radical polymerization (ATRP) of zwitterionic poly(sulfobetaine methacrylate) (polySBMA) grafted from biomedical grade stainless steel surface was employed in this study. The interactions of polySBMA-grafted surfaces with biomacromolecules were demonstrated in vitro by the adhesion tests of plasma protein, blood cells, human MG63 osteoblast- and HT1080 fibroblast-like cells in biological complex media to evaluate their bioadhesive properties. Anti-microbial effects were also assessed for two most ordinary seen clinical bacteria, i.e., Escherichia coli and Staphylococcus epidermidis. Results showed that polySBMA-grafted surface exhibited evident bioadhesion resistance and conferring antibacterial efficacy. This work is also dedicated to deduce the effectiveness of polySBMA brushes' conformational structure on the prevention of bioadhesion. To this aim, the anti-bioadhesive effect of polySBMA brushes prepared by dopamine- and silane-surfaced immobilization method was evaluated. Results show that polySBMA grafted from immobilized polydopamine interfacial layers achieved better bioadhesion resistance, which could be causally related to their greater grafting coverage, flexible brush conformational structures, and greater hydration capabilities.

A graphene/zinc oxide nanocomposite film protects dental implant surfaces against cariogenic Streptococcus mutans

Oral biofilms play a crucial role in the development of dental caries and other periodontal diseases. Streptococcus mutans is one of the primary etiological agents in dental caries. Implant systems are regularly employed to replace missing teeth. Oral biofilms accumulate on these implants and are the chief cause of dental implant failure. In the present study, the potential of graphene/zinc oxide nanocomposite (GZNC) against the cariogenic properties of Streptococcus mutans was explored and the anti-biofilm behaviour of artificial acrylic teeth surfaces coated with GZNC was examined. Acrylic teeth are a good choice for implants as they are low cost, have low density and can resist fracture. Microscopic studies and anti-biofilm assays showed a significant reduction in biofilm in the presence GZNC. GZNC was also found to be nontoxic against HEK-293 (human embryonic kidney cell line). The results indicate the potential of GZNC as an effective coating agent for dental implants by efficiently inhibiting S. mutans biofilms.

Peri-implantitis: etiology, diagnosis and treatment: an update

Peri-implant mucositis is described as the presence of inflammation in the mucosa around implants without any bone loss. By contrast, in peri-implantitis, besides the inflammation in the peri-implant mucosa, loss of supporting bone is also seen. The probing depth, the presence of bleeding on probing, suppuration and radiographs should be assessed regularly for the diagnosis of peri-implant diseases. Poor oral hygiene, smoking and previous history of periodontitis are known risk factors for the disease. The occlusion and longevity of fixed partial dentures around implants, whether connected to the natural teeth or not, is still an area of investigaton, but studies show that long-term results are acceptable for both. Various treatment modalities are discussed in relation to the management of periimplantitis. The predictable outcome of peri-implantitis management is not yet known.

[Bacteriological monitoring of patients with periimplantitis (preliminary study)]

Studied the microflora properties of pockets around implants of 14 patients at the age of 35-68 years old. The research has shown the presence of pathogens, who p included into PRC diagnosis. Lhe research also revealed high prevalence of obligate piriodontak pathogens in areas of inflammation during periimplantitis. with both full and partial adentia.

Patient-specific analysis of periodontal and peri-implant microbiomes

Periodontally involved teeth have been implicated as 'microbial reservoirs' in the etiology of peri-implant diseases. Therefore, the purpose of this investigation was to use a deep-sequencing approach to identify the degree of congruence between adjacent peri-implant and periodontal microbiomes in states of health and disease. Subgingival and peri-implant biofilm samples were collected from 81 partially edentulous individuals with periodontal and peri-implant health and disease. Bacterial DNA was isolated, and the 16S rRNA gene was amplified and sequenced by pyrotag sequencing. Chimera-depleted sequences were compared against a locally hosted curated database for bacterial identification. Statistical significance was determined by paired Student's t tests between tooth-implant pairs. The 1.9 million sequences identified represented 523 species. Sixty percent of individuals shared less than 50% of all species between their periodontal and peri-implant biofilms, and 85% of individuals shared less than 8% of abundant species between tooth and implant. Additionally, the periodontal microbiome demonstrated significantly higher diversity than the implant, and distinct bacterial lineages were associated with health and disease in each ecosystem. Analysis of our data suggests that simple geographic proximity is not a sufficient determinant of colonization of topographically distinct niches, and that the peri-implant and periodontal microbiomes represent microbiologically distinct ecosystems.

Dimensional and microbiological in vitro analysis of a dental implant locking taper connection

The present study was carried out to compare the differences in contact, height and contact area between the implant-abutment interface and the implant-healing cap interface of an implant system featuring a locking tapered connection by using X-ray micro-tomography. It was also conducted to test in vitro whether the implant-healing cap tapered interface is capable of preventing bacterial leakage from the implant well to the external environment. The images of the samples, acquired by the X-ray micro-tomography, after being processed with a dedicated software, showed a greater contact height (CH) in the implant-abutment sample (3.57 mm) compared to the implant-healing cap sample (2.52 mm). This was also true for the contact area that was equal to 40.63 mm2 in the implant-abutment sample and 25.14 mm2 in the implant-healing cap sample. No bacteria were detected both in the nutrient of the test group and of the negative control after 24 h. An increased contact height and contact area in a tapered connection, between the implant and the abutment, have demonstrated to offer mechanical and biological advantages, in a implant-healing cap tapered connection. The major concern regards the microbiological aspects of this connection. The implant-healing cap tapered connection provides an hermetic barrier to microbial passage in vitro, even though such connection features lower contact height and contact area compared to the implant-abutment connection of the same implant system.