Genome analysis and clinical implications of the bacterial communities in early biofilm formation on dental implants restored with titanium or zirconia abutments

Comparison of Microbiota in Zirconia and Titanium Implants: A Qualitative Systematic Review

BACKGROUND

In this systematic review, we examine the variations in microbiota on zirconia versus titanium implants, providing insights into their impact on dental health and outcomes. The ongoing discussion regarding whether to use zirconia or titanium for implants underscores the significance of microbiota colonization in determining the longevity and performance of implants.

METHODS

Research questions were formulated following the Participants, Intervention, Comparison, and Outcomes framework, and a PROSPERO protocol was registered. A thorough systematic search was carried out in PubMed, Embase, and Web of Science. Two reviewers independently assessed the reports against the Participants, Intervention, Comparison, and Outcomes criteria, including the inclusion and exclusion criteria. Risk of bias was assessed using the Quality Assessment Tool for In Vitro Studies (QUIN Tool).

RESULTS

Of the 2063 articles identified, 19 articles fulfilled the inclusion criteria and subjected to quality assessment. All of the included studies were in vitro research with low (31.5%) or moderate (36.8%) or high (31.5%) risk of bias and reported data from 2 implant abutments. Zirconia implants displayed a higher occurrence of Gram-negative bacteria, such as Tannerella, Aggregatibacter, and Porphyromonas. In contrast, titanium implants showed a greater prevalence of Gram-positive bacteria, including Streptococcus, Lactobacillus acidophilus, and Staphylococcus species.

CONCLUSION

According to the findings of the current study, both zirconia and titanium implants support the growth of different microorganisms. There were also differences in the quakity and the quantity of microorganisms detected on each material. These differences in microbial profiles indicate that the selection of implant material might impact the microbial ecosystem on the implant surface, potentially affecting clinical outcomes such as infection rates and the longevity of the implant.

Microbiome and the inflammatory pathway in peri-implant health and disease with an updated review on treatment strategies

Crestal bone preservation around the dental implant for aesthetic and functional success is widely researched and documented over a decade. Several etiological factors were put forth for crestal bone loss; of which biofilm plays a major role. Biofilm is formed by the colonization of wide spectra of bacteria inhabited around dental implants. Bacterial adherence affects the regulators of bone growth and an early intervention preserves the peri-implant bone. Primary modes of therapy stated in early literature were either prevention or treatment of infection caused by biofilm. This narrative review overviews the microbiome during different stages of peri-implant health, the mechanism of bone destruction, and the expression of the biomarkers at each stage. Microbial contamination and the associated biomarkers varied depending on the stage of peri-implant infection. The comprehensive review helps in formulating a research plan, both in diagnostics and treatment aspects in improving peri-implant health.

Overview of Antibacterial Strategies of Dental Implant Materials for the Prevention of Peri-Implantitis

As dental implants have become one of the main treatment options for patients with tooth loss, the number of patients with peri-implant diseases has increased. Similar to periodontal diseases, peri-implant diseases have been associated with dental plaque formation on implants. Unconventional approaches have been reported to remove plaque from infected implants, but none of these methods can completely and permanently solve the problem of bacterial invasion. Fortunately, the constant development of antibacterial implant materials is a promising solution to this situation. In this review, the development and study of different antibacterial strategies for dental implant materials for the prevention of peri-implantitis are summarized. We hope that by highlighting the advantages and limitations of these antimicrobial strategies, we can assist in the continued development of oral implant materials.

Microbiological findings in early and late implant loss: an observational clinical case-controlled study

Background

Implants are a predictable and well-established treatment method in dentistry. Nevertheless, looking at possible failures of dental implants, early and late loss have to be distinguished. The intent of the study was to report microbiological findings on the surface of implants with severe peri-implantitis, which had to be explanted.

Methods

53 specimens of implants from 48 patients without severe general illnesses have been examined. The groups investigated were implants that had to be removed in the period of osseointegration (early loss, 13 patients with 14 implants) or after the healing period (late loss, 14 patients with 17 implants). The implant losses were compared with two control groups (implants with no bone loss directly after completed osseointegration, two to four months after implant placement (17 patients with 17 implants) and implants with no bone loss and prosthetic restoration for more than three years (5 patients with 5 implants)). Data about the bacteria located in the peri-implant sulcus was collected using amplification and high throughput sequencing of the 16S rRNA gene.

Results

The biofilm composition differed substantially between individuals. Both in early and late implant loss, Fusobacterium nucleatum and Porphyromonas gingivalis were found to be abundant. Late lost implants showed higher bacterial diversity and in addition higher abundances of Treponema, Fretibacterium, Pseudoramibacter and Desulfobulbus, while microbial communities of early loss implants were very heterogeneous and showed no significantly more abundant bacterial taxa.

Conclusions

Specific peri-implant pathogens were found around implants that were lost after a primarily uneventful osseointegration. P. gingivalis and F. nucleatum frequently colonized the implant in early and late losses and could therefore be characteristic for implant loss in general. In general, early lost implants showed also lower microbial diversity than late losses. However, the microbial results were not indicative of the causes of early and late losses.

Clinical study of the biofilm of implant-supported complete dentures in healthy patients

OBJECTIVE

The purpose of this study was to quantify the area covered by biofilm and identify bacteria and yeasts present in mandibular acrylic resin full-arch implant-supported fixed prostheses.

BACKGROUND

Biofilm control of implant-supported fixed prosthesis is hampered by their design, and it can cause oral and systemic problems, mainly in immunocompromised patients like the elder. Knowledge about microbiota reinforces the awareness about the need for periodic professional cleaning maintenance.

MATERIALS AND METHODS

Twenty prostheses were unscrewed, washed in 0.89% sodium chloride, stained with eosin 1% and photographed. The area covered by biofilm was digitally delimited and quantified. Biofilm samples were collected, diluted up to 1:10⁷ , seeded in chromogenic agar media and incubated for 48 hours, at 37°C, for counting of colony-forming units (CFU/mL). DNA hybridization was performed to complement the identification and quantification of microorganisms. Data were analyzed using Mann-Whitney test, Spearman correlation and Fisher's exact test (α = .05).

RESULTS

An average of 62% of the gingival surface of the prostheses was covered by biofilm. Enterococcus spp. (5.82 ± 1.38 log₁₀ CFU/mL) and Staphylococcus aureus (5.75 ± 2.02 log₁₀ CFU/mL) showed higher prevalence in cultures. Patients with five implants had less biofilm compared to those with four implants (P = .031) but had higher Escherichia coli counts (P = .039). In DNA hybridization, Streptococcus pneumoniae, Veillonella parvula and Fusobacterium nucleatum presented higher quantification and were present in all the samples; patients over 65 years old contained more Candida tropicalis (P = .049); prostheses on five implants presented lower quantification for several species.

CONCLUSION

Biofilm was present on all prostheses, containing potentially pathogenic microorganisms. The number of implants may play a role in quantification of biofilm and in microorganism counts.

Surface Roughness and Streptococcus mutans Adhesion on Metallic and Ceramic Fixed Prosthodontic Materials after Scaling

The aim of this study was to evaluate the surface roughness of fixed prosthodontic materials after polishing or roughening with a stainless steel curette or ultrasonic scaler and to examine the effect of these on Streptococcus mutans adhesion and biofilm accumulation. Thirty specimens (10 × 10 × 3 mm³) of zirconia (Zr), pressed lithium disilicate (LDS-Press), milled lithium disilicate glazed (LDS-Glaze), titanium grade V (Ti) and cobalt-chromium (CoCr) were divided into three groups (n = 10) according to surface treatment: polished (C), roughened with stainless steel curette (SC), roughened with ultrasonic scaler (US). Surface roughness values (Sa, Sq) were measured with a spinning disc confocal microscope, and contact angles and surface free energy (SFE) were measured with a contact angle meter. The specimens were covered with sterilized human saliva and immersed into Streptococcus mutans suspensions for bacterial adhesion. The biofilm was allowed to form for 24 h. Sa values were in the range of 0.008–0.139 µm depending on the material and surface treatment. Curette and ultrasonic scaling increased the surface roughness in LDS-Glaze (p < 0.05), Ti (p < 0.01) and CoCr (p < 0.001), however, surface roughness did not affect bacterial adhesion. Zr C and US had a higher bacterial adhesion percentage compared to LDS-Glaze C and US (p = 0.03). There were no differences between study materials in terms of biofilm accumulation.

Microbial communities of titanium versus zirconia abutments on implant-supported restorations: Biodiversity composition and its impact on clinical parameters over a 3-year longitudinal prospective study

BACKGROUND

Shifts in microbial communities are common over time, but they may disturb the host-microbiome homeostasis and result in inflammation of the peri-implant issues if a dysbiotic biofilm is established.

PURPOSE

Considering that different oral substrate surfaces may have a relevant impact on the microbial adhesion and colonization, the aim of this study was to investigate the microbial communities of the biofilm formed on single-implant restorations using titanium or zirconia abutments and how they correlate with clinical parameters after 3-years of implant loading.

MATERIALS AND METHODS

MiSeq sequencing of 16S rRNA amplicons was used to characterize the oral biofilms of individuals (n = 20) who were sampled longitudinally during 3 years of masticatory loading. Bioinformatics analysis and multivariate statistical analysis were used to evaluate the microbial diversity and clinical outcomes.

RESULTS

Microbiomes of both abutment materials presented high alpha-diversity indices during all the experimental period, irrespective of the time of sampling. Microbial communities of titanium and zirconia were quite different over time, differing about 30% after 3 years of functional loading. Similarity of microbiomes between tested abutments and contralateral teeth was also low, ranging between 45% and 50% after 3 years of investigation. Periodontal pathogens commonly associated with peri-implantitis were found in both groups. Furthermore, both abutment materials presented strong correlations of diversity indices and microbial taxa with clinical outcomes.

CONCLUSIONS

The type of abutment substrate significantly influenced diversity and clustering of communities during 3 years of functional loading. The time of sampling had no effect on the variables. Large correlations were found between microbial findings and clinical outcomes.

Bioadhesion in the oral cavity and approaches for biofilm management by surface modifications

BACKGROUND

All soft and solid surface structures in the oral cavity are covered by the acquired pellicle followed by bacterial colonization. This applies for natural structures as well as for restorative or prosthetic materials; the adherent bacterial biofilm is associated among others with the development of caries, periodontal diseases, peri-implantitis, or denture-associated stomatitis. Accordingly, there is a considerable demand for novel materials and coatings that limit and modulate bacterial attachment and/or propagation of microorganisms.

OBJECTIVES AND FINDINGS

The present paper depicts the current knowledge on the impact of different physicochemical surface characteristics on bioadsorption in the oral cavity. Furthermore, it was carved out which strategies were developed in dental research and general surface science to inhibit bacterial colonization and to delay biofilm formation by low-fouling or "easy-to-clean" surfaces. These include the modulation of physicochemical properties such as periodic topographies, roughness, surface free energy, or hardness. In recent years, a large emphasis was laid on micro- and nanostructured surfaces and on liquid repellent superhydrophic as well as superhydrophilic interfaces. Materials incorporating mobile or bound nanoparticles promoting bacteriostatic or bacteriotoxic properties were also used. Recently, chemically textured interfaces gained increasing interest and could represent promising solutions for innovative antibioadhesion interfaces. Due to the unique conditions in the oral cavity, mainly in vivo or in situ studies were considered in the review.

CONCLUSION

Despite many promising approaches for modulation of biofilm formation in the oral cavity, the ubiquitous phenomenon of bioadsorption and adhesion pellicle formation in the challenging oral milieu masks surface properties and therewith hampers low-fouling strategies.

CLINICAL RELEVANCE

Improved dental materials and surface coatings with easy-to-clean properties have the potential to improve oral health, but extensive and systematic research is required in this field to develop biocompatible and effective substances.

Iodoform and silver-coated abutments preventing bacterial leakage through the implant-abutment interfaces: In vitro analysis using molecular-based method

OBJECTIVES

The aim of this in vitro study was to evaluate the effectiveness of an iodoform paste and silver-coated abutments in preventing the microbial colonization and leakage through the implant-abutment interface of morse taper and internal hexagon implants.

MATERIAL AND METHODS

Seventy-two implants with morse taper (n = 36) or internal hexagon connections (n = 36) were investigated. Implants were treated with iodoform paste (n = 12), silver-coated abutments (n = 12), or control (n = 12). After saliva incubation, Checkerboard DNA-DNA hybridization was used to identify and quantify up to 43 microbial species colonizing the inner parts of the implants. ANOVA-Type and Wald-Type analyses of variance were used to investigate the relative effects and their interaction. Friedman- Conover test adjusted by Benjamini-Hockberg FDR were performed for pairwise multiple comparisons. Significance was set as p < 0.05.

RESULTS

Analyses of variance indicate a significant interaction between connections, antimicrobial treatments, and species. The frequency of contamination was reduced in the implants submitted to the antimicrobial treatments. Iodoform and silver-coated abutments significantly reduced the total microbial counts in the internal hexagon implants. The lower microbial counts were recorded for morse taper implants with silver-coated abutments.

CONCLUSIONS

Iodoform paste and silver-coated abutments have influenced the microbial leakage through the implant-abutment interface, by reducing both frequency of contamination and microbial levels. Treatments were not effective in reducing the counts of the target species.

Influence of Dental Prosthesis and Restorative Materials Interface on Oral Biofilms

Oral biofilms attach onto both teeth surfaces and dental material surfaces in oral cavities. In the meantime, oral biofilms are not only the pathogenesis of dental caries and periodontitis, but also secondary caries and peri-implantitis, which would lead to the failure of clinical treatments. The material surfaces exposed to oral conditions can influence pellicle coating, initial bacterial adhesion, and biofilm formation, due to their specific physical and chemical characteristics. To define the effect of physical and chemical characteristics of dental prosthesis and restorative material on oral biofilms, we discuss resin-based composites, glass ionomer cements, amalgams, dental alloys, ceramic, and dental implant material surface properties. In conclusion, each particular chemical composition (organic matrix, inorganic filler, fluoride, and various metallic ions) can enhance or inhibit biofilm formation. Irregular topography and rough surfaces provide favorable interface for bacterial colonization, protecting bacteria against shear forces during their initial reversible binding and biofilm formation. Moreover, the surface free energy, hydrophobicity, and surface-coating techniques, also have a significant influence on oral biofilms. However, controversies still exist in the current research for the different methods and models applied. In addition, more in situ studies are needed to clarify the role and mechanism of each surface parameter on oral biofilm development.