RCT comparing minimally with moderately rough implants. Part 2: microbial observations

Impact of surface characteristics on the peri-implant microbiome in health and disease

BACKGROUND

Because little is known about the impact of implant surface modifications on the peri-implant microbiome, we aimed to examine peri-implant communities in various surface types in order to better understand the impact of these surfaces on the development of peri-implantitis (PI).

METHODS

One hundred and six systemically healthy individuals with anodized (AN), hydroxyapatite-coated (HA), or sandblasted acid-etched (SLA) implants that were >6 months in function were recruited and categorized into health (H) or PI. Peri-implant biofilm was analyzed using 16S rRNA gene sequencing and compared between health/disease and HA/SLA/AN using community-level and taxa-level metrics.

RESULTS

Healthy implants did not demonstrate significant differences in clustering, alpha- or beta-diversity based on surface modification. AN and HA surfaces displayed significant differences between health and PI (p < 0.05); however, such a clustering was not evident with SLA (p > 0.05). AN and HA surfaces also differed in the magnitude and diversity of differences between health and PI. Six species belonging to the genera Shuttleworthia, Scardovia, and Prevotella demonstrated lower abundances in AN implants with PI, and 18 species belonging to the genera Fretibacterium, Tannerella, Treponema, and Fusobacterium were elevated, while in HA implants with PI, 20 species belonging to the genera Streptococcus, Lactobacillus, Veillonella, Rothia, and family Ruminococcaceae were depleted and Peptostreptococcaceae, Atopobiaceae, Veillonellaceae, Porphyromonadaceae, Desulfobulbaceae, and order Synergistales were enriched.

CONCLUSIONS

Within the limitations of this study, we demonstrate that implant surface can differentially modify the disease-associated microbiome, suggesting that surface topography must be considered in the multi-factorial etiology of peri-implant diseases.

Surface Modifications of Commercial Dental Implant Systems: An Overview

The aim of this review was to perform a comprehensive overview of evidence pertaining to the influence of various surface modifications on the surface roughness, bone implant contact, and the success and complication rates of the implants. Modified sandblasted, large-grit, acid-etched (SLA) implants (SLActive implants) have a higher implant stability quotient compared with conventional SLA implants. Also, when compared between the implant surfaces from various manufacturers, Biomet 3i Nanotite implants were shown to have a relatively higher implant stability quotient compared to Straumann implants as well as the Biomet Osseotite implants. Only one study reports the insertion torque values as obtained by the various implant surfaces, with the findings being statistically similar for all the types, and a higher mean value for Biomet 3i Nanotite implants. Among SLA and SLActive surfaces, the latter was found to have a lower marginal bone loss, and among Astratech implants, the marginal bone loss levels were similar for Osseospeed and Tioblast surfaces. When Osseospeed, TiUnite and SLActive surfaces were compared, Osseospeed was found to have the minimum bone loss while TiUnite was found to have the highest. The bone implant contact percentages are similar and satisfactory for most of the implant surface modifications that are available currently. Upon assessing the recent literature on the survival rates for implants with various surface modifications, it was found that among Nobel Biocare implants, the survival rate was higher for TiUnite implants, compared with the turned surfaces. Surprisingly, among the Straumann implant surfaces, the survival rates were found to be higher for the SLA implants when compared to the modified SLA implants. Only one of the included studies evaluated the survival rate for Astratech implant surfaces and found a 100% survival rate for both the Osseospeed and Tioblast surface implants. Therefore, major advancements have been made in developing novel surfaces of dental implants. The numerous innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

Submucosal microbiome of peri-implant sites: A cross-sectional study

AIM

To study the peri-implant submucosal microbiome in relation to implant disease status, dentition status, smoking habit, gender, implant location, implant system, time of functional loading, probing pocket depth (PPD), and presence of bleeding on probing.

MATERIALS AND METHODS

Biofilm samples were collected from the deepest peri-implant site of 41 patients with paper points, and analysed using 16S rRNA gene pyrosequencing.

RESULTS

We observed differences in microbial profiles by PPD, implant disease status, and dentition status. Microbiota in deep pockets included higher proportions of the genera Fusobacterium, Prevotella, and Anaeroglobus compared with shallow pockets that harboured more Rothia, Neisseria, Haemophilus, and Streptococcus. Peri-implantitis (PI) sites were dominated by Fusobacterium and Treponema compared with healthy implants and peri-implant mucositis, which were mostly colonized by Rothia and Streptococcus. Partially edentulous (PE) individuals presented more Fusobacterium, Prevotella, and Rothia, whereas fully edentulous individuals presented more Veillonella and Streptococcus.

CONCLUSIONS

PPD, implant disease status, and dentition status may affect the submucosal ecology leading to variation in composition of the microbiome. Deep pockets, PI, and PE individuals were dominated by Gram-negative anaerobic taxa.

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., 3D printing (3DP) and laser surface texturing (LST)), micro-scale (e.g., grit-blasting, acid-etching, and Sand-blasted, Large-grit, and Acid-etching (SLA)) and nano-scale methods (e.g., plasma-spraying and anodization) are also discussed, and these surfaces are known to have favorable properties in clinical applications. Functionalized coatings with organic and non-organic loadings suggest good prospects for the future of modern biotechnology. Nevertheless, because of high cost and low clinical validation, these partial coatings have not been commercially available so far. A large number of in vitro and in vivo investigations are necessary in order to obtain in-depth exploration about the efficiency of functional implant surfaces. The prospective titanium implants should possess the optimum chemistry, bionic characteristics, and standardized modern topographies to achieve rapid osseointegration.

WITHDRAWN: Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant designs and surface modifications have been developed for improving clinical outcome. This is an update of a Cochrane review first published in 2002, and previously updated in 2003, 2005 and 2007.

OBJECTIVES

Primary: to compare the clinical effects of different root-formed osseointegrated dental implant types for replacing missing teeth for the following specific comparisons: implants with different surface preparations, but having similar shape and material; implants with different shapes, but having similar surface preparation and material; implants made of different materials, but having similar surface preparation and shape; different implant types differing in surface preparation, shape, material or a combination of these.Secondary: to compare turned and roughened dental implants for occurrence of early implant failure (before prosthetic loading) and occurrence of peri-implantitis.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 17 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE via OVID (1946 to 17 January 2014) and EMBASE via OVID (1980 to 17 January 2014). We placed no restrictions on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) comparing osseointegrated dental implants of different materials, shapes and surface properties having a follow-up in function of at least one year. Outcome measures were success of the implants, radiographic peri-implant marginal bone levels changes and incidence of peri-implantitis.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted screening, risk of bias assessment and data extraction of eligible trials in duplicate. We expressed results using fixed-effect models (if up to three studies were present in a meta-analysis) or random-effects models (when there were more than three studies) using mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI). We reported the following endpoints: one, three, five and 10 years after functional loading.

MAIN RESULTS

We identified 81 different RCTs. We included 27 of these RCTs, reporting results from 1512 participants and 3230 implants in the review. We compared 38 different implant types with a follow-up ranging from one to 10 years. All implants were made of commercially pure titanium or its alloys, and had different shapes and surface preparations. We judged two trials to be at low risk of bias, 10 to be at unclear risk of bias and 15 to be at high risk of bias. On a 'per participant' rather than 'per implant' basis, we found no significant differences between various implant types for implant failures. The only observed statistically significant difference for the primary objective regarded more peri-implant bone loss at Nobel Speedy Groovy implants when compared with NobelActive implants (MD -0.59 mm; 95% CI -0.74 to -0.44, different implant shapes). The only observed statistically significant difference for the secondary objective was that implants with turned (smoother) surfaces had a 20% reduction in risk to be affected by peri-implantitis than implants with rough surfaces three years after loading (RR 0.80; 95% CI 0.67 to 0.96). There was a tendency for implants with turned surfaces to fail early more often than implants with roughened surfaces.

AUTHORS' CONCLUSIONS

Based on the results of the included RCTs, we found no evidence showing that any particular type of dental implant had superior long-term success. There was limited evidence showing that implants with relatively smooth (turned) surfaces were less prone to lose bone due to chronic infection (peri-implantitis) than implants with much rougher surfaces (titanium-plasma-sprayed). These findings were based on several RCTs, often at high risk of bias, with few participants and relatively short follow-up periods.

Nano-scale modification of titanium implant surfaces to enhance osseointegration

The main aim of this review study was to report the state of art on the nano-scale technological advancements of titanium implant surfaces to enhance the osseointegration process. Several methods of surface modification are chronologically described bridging ordinary methods (e.g. grit blasting and etching) and advanced physicochemical approaches such as 3D-laser texturing and biomimetic modification. Functionalization procedures by using proteins, peptides, and bioactive ceramics have provided an enhancement in wettability and bioactivity of implant surfaces. Furthermore, recent findings have revealed a combined beneficial effect of micro- and nano-scale modification and biomimetic functionalization of titanium surfaces. However, some technological developments of implant surfaces are not commercially available yet due to costs and a lack of clinical validation for such recent surfaces. Further in vitro and in vivo studies are required to endorse the use of enhanced biomimetic implant surfaces. STATEMENT OF SIGNIFICANCE: Grit-blasting followed by acid-etching is currently used for titanium implant modifications, although recent technological biomimetic physicochemical methods have revealed enhanced osteoconductive and anti-microbial outcomes. An improvement in wettability and bioactivity of titanium implant surfaces has been accomplished by combining micro and nano-scale modification and functionalization with protein, peptides, and bioactive compounds. Such morphological and chemical modification of the titanium surfaces induce the migration and differentiation of osteogenic cells followed by an enhancement of the mineral matrix formation that accelerate the osseointegration process. Additionally, the incorporation of bioactive molecules into the nanostructured surfaces is a promising strategy to avoid early and late implant failures induced by the biofilm accumulation.

Prevalence of Peri-Implantitis in Implants with Turned and Rough Surfaces: a Systematic Review

Objectives

Moderately-rough implant surface may improve implant therapy in terms of bone integration, but the increased surface roughness might affect the initiation and development of peri-implantitis. The aim of the present review was to compare the prevalence of peri-implantitis in implants with rough and turned (machined) implant surfaces.

Material and Methods

An electronic literature search was conducted of the MEDLINE and EMBASE databases for articles published between 1 January 1990 and 1 March 2018. Clinical human studies in the English language that had reported on prevalence of peri-implantitis in tuned and rough surface implants were searched. The initial search resulted in 690 articles.

Results

Eight articles with 2992 implants were included in the systematic review. The incidence of peri-implantitis for two implant surfaces varied between studies. A meta-analysis was not feasible due to the heterogeneity among studies. Implant with rough surfaces were more favourable for plaque accumulation during short-term follow-up. On a long-term, turned implants surfaces were associated with more plaque and higher peri-implant bone loss. Peri-implant clinical parameters and survival rate for two implant surfaces was similar.

Conclusions

Within the limitations of the present study, rough implant surface does not seem to increase the incidence of peri-implantitis in comparison to turned implants surface.

Analysis of osteogenic potential on 3mol% yttria-stabilized tetragonal zirconia polycrystals and two different niobium oxide containing zirconia ceramics

PURPOSE

This study was performed to evaluate the osteogenic potential of 3mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) and niobium oxide containing Y-TZPs with specific ratios, new (Y,Nb)-TZPs, namely YN4533 and YN4533/Al20 discs.

MATERIALS AND METHODS

3Y-TZP, YN4533 and YN4533/Al20 discs (15 mm diameter and 1 mm thickness) were prepared and their average surface roughness (R_a) and surface topography were analyzed using 3-D confocal laser microscope (CLSM) and scanning electron microscope (SEM). Mouse pre-osteoblast MC3T3-E1 cells were seeded onto all zirconia discs and evaluated with regard to cell attachment and morphology by (CLSM), cell proliferation by PicoGreen assay, and cell differentiation by Reverse-Transcription PCR and Quantitative Real-Time PCR, and alkaline phosphatase (Alp) staining.

RESULTS

The cellular morphology of MC3T3-E1 pre-osteoblasts was more stretched on a smooth surface than on a rough surface, regardless of the material. Cellular proliferation was higher on smooth surfaces, but there were no significant differences between 3Y-TZP, YN4533, and YN4533/Al20. Osteoblast differentiation patterns on YN4533 and YN4533/Al20 were similar to or slightly higher than seen in 3Y-TZP. Although there were no significant differences in bone marker gene expression (alkaline phosphatase and osteocalcin), Alp staining indicated better osteoblast differentiation on YN4533 and YN4533/Al20 compared to 3Y-TZP.

CONCLUSION

Based on these results, niobium oxide containing Y-TZPs have comparable osteogenic potential to 3Y-TZP and are expected to be suitable alternative ceramics dental implant materials to titanium for aesthetically important areas.

Impact of Dental Implant Surface Modifications on Osseointegration

Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

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.

Implants with an Oxidized Surface Placed Predominately in Soft Bone Quality and Subjected to Immediate Occlusal Loading: Results from an 11-Year Clinical Follow-Up

PURPOSE

The purpose of this clinical follow-up was to document the 11-year outcome of implants with a moderately rough oxidized surface subjected to immediate occlusal loading.

MATERIALS AND METHODS

Twenty-six of 38 patients enrolled in a 5-year prospective study were available for this follow-up analysis, with 33 restorations supported by 66 slightly tapered implants (Brånemark System MkIV, Nobel Biocare, Gothenburg, Sweden). The majority of implants were placed in posterior regions (88%) and into soft bone (76%). Parameters included cumulative survival rate (CSR), radiographic marginal bone level, bleeding on probing (BOP), intrasulcular counts of perio-pathogenic markers (DNA probes), and total bacterial load (TBL).

RESULTS

The CSR was 97.1% at 11.2 years mean follow-up. Mean marginal bone remodeling was 0.47 mm (SD 1.09, n = 65) from 1 year postplacement to 11-year follow-up. BOP was absent at most sites (63.6%). No statistically significant differences in TBL or perio-pathogenic marker species were observed at implants and teeth.

CONCLUSION

The results of the present follow-up show high long-term survival, stable marginal bone levels, and soft tissue outcomes of oxidized surface implants placed predominately in posterior regions and soft bone. The quantity and quality of intrasulcular microbiota were comparable at implants and teeth.

Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant designs and surface modifications have been developed for improving clinical outcome. This is an update of a Cochrane review first published in 2002, and previously updated in 2003, 2005 and 2007.

OBJECTIVES

Primary: to compare the clinical effects of different root-formed osseointegrated dental implant types for replacing missing teeth for the following specific comparisons: implants with different surface preparations, but having similar shape and material; implants with different shapes, but having similar surface preparation and material; implants made of different materials, but having similar surface preparation and shape; different implant types differing in surface preparation, shape, material or a combination of these.Secondary: to compare turned and roughened dental implants for occurrence of early implant failure (before prosthetic loading) and occurrence of peri-implantitis.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 17 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE via OVID (1946 to 17 January 2014) and EMBASE via OVID (1980 to 17 January 2014). We placed no restrictions on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) comparing osseointegrated dental implants of different materials, shapes and surface properties having a follow-up in function of at least one year. Outcome measures were success of the implants, radiographic peri-implant marginal bone levels changes and incidence of peri-implantitis.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted screening, risk of bias assessment and data extraction of eligible trials in duplicate. We expressed results using fixed-effect models (if up to three studies were present in a meta-analysis) or random-effects models (when there were more than three studies) using mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI). We reported the following endpoints: one, three, five and 10 years after functional loading.

MAIN RESULTS

We identified 81 different RCTs. We included 27 of these RCTs, reporting results from 1512 participants and 3230 implants in the review. We compared 38 different implant types with a follow-up ranging from one to 10 years. All implants were made of commercially pure titanium or its alloys, and had different shapes and surface preparations. We judged two trials to be at low risk of bias, 10 to be at unclear risk of bias and 15 to be at high risk of bias. On a 'per participant' rather than 'per implant' basis, we found no significant differences between various implant types for implant failures. The only observed statistically significant difference for the primary objective regarded more peri-implant bone loss at Nobel Speedy Groovy implants when compared with NobelActive implants (MD -0.59 mm; 95% CI -0.74 to -0.44, different implant shapes). The only observed statistically significant difference for the secondary objective was that implants with turned (smoother) surfaces had a 20% reduction in risk to be affected by peri-implantitis than implants with rough surfaces three years after loading (RR 0.80; 95% CI 0.67 to 0.96). There was a tendency for implants with turned surfaces to fail early more often than implants with roughened surfaces.

AUTHORS' CONCLUSIONS

Based on the results of the included RCTs, we found no evidence showing that any particular type of dental implant had superior long-term success. There was limited evidence showing that implants with relatively smooth (turned) surfaces were less prone to lose bone due to chronic infection (peri-implantitis) than implants with much rougher surfaces (titanium-plasma-sprayed). These findings were based on several RCTs, often at high risk of bias, with few participants and relatively short follow-up periods.

Implant surface factors and bacterial adhesion: a review of the literature

The microbiota that forms on implant surfaces placed in the human body can be highly resistant to antimicrobial agents and in some cases cause life-threatening infections. Consequently, to limit bacterial attachment to these surfaces and thereby minimize the risk of implant infection, the process of biofilm formation and bacterial attachment must be well-understood. The oral environment is considered to be an excellent model for research into biofilm formation and implant infection, accounting for many studies carried out in the field of dental medicine. Those studies show that the roughness, free energy, and material characteristics of the implant surface largely determine initial bacterial adhesion. This article reviews the relevant literature on these aspects of biofilm formation.

In vivo evaluation of a novel implant coating agent: laminin-1

PURPOSE

The aim of this study was to assess the effect of implant coating with laminin-1 on the early stages of osseointegration in vivo.

MATERIALS AND METHODS

Turned titanium implants were coated with the osteoprogenitor-stimulating protein, laminin-1 (TL). Their osteogenic performance was assessed with removal torque, histomorphometry, and nanoindentation in a rabbit model after 2 and 4 weeks. The performance of the test implants was compared with turned control implants (T), alkali- and heat-treated implants (AH), and AH implants coated with laminin-1.

RESULTS

After 2 weeks, TL demonstrated significantly higher removal torque as compared with T and equivalent to AH. Bone area was significantly higher for the test surface after 4 weeks, while no significant changes were detected on the micromechanical properties of the surrounding bone.

CONCLUSIONS

Within the limitations of this study, our results suggest a great potential for laminin-1 as a coating agent. A turned implant surface coated with laminin-1 could enhance osseointegration comparable with a bioactive implant surface while keeping the surface smooth.

Novel Implant Coating Agent Promotes Gene Expression of Osteogenic Markers in Rats during Early Osseointegration

The aim of this study was to evaluate the early bone response around laminin-1-coated titanium implants. Forty-five rats distributed in three equally sized groups were provided with one control (turned) and one test (laminin-1-coated) implant and were sacrificed after 3, 7, and 21 days. Real-time reverse-transcriptase polymerase chain reaction was performed for osteoblast markers (alkaline phosphatase, runt-related transcription factor 2, osteocalcin, type I collagen, and bone morphogenic protein 2), osteoclast markers (cathepsin K and tartrate-resistant acid phosphatase), inflammation markers (tumor necrosis factor α, interleukin 1β and interleukin 10), and integrin β1. Bone implant contact (BIC) and bone area (BA) were assessed and compared to the gene expression. After 3 days, the expression of bone markers was higher for the control group. After 7 days, the expression of integrin β1 and osteogenic markers was enhanced for the test group, while cathepsin K and inflammation markers were down-regulated. No significant differences in BIC or BA were detected between test and control at any time point. As a conclusion, implant coating with laminin-1 altered gene expression in the bone-implant interface. However, traditional evaluation methods, as histomorphometry, were not adequately sensitive to detect such changes due to the short follow-up time.