Current Concepts on the Pathogenesis of Peri-implantitis: A Narrative Review

A microtomographic and histopathological evaluation of dental cements as late-stage peri-implant complication in a rat model

Cement mediated peri-implantitis accounts for 1.9-75% of dental implant failures associated with peri-implant diseases. This study evaluated the biological impact of dental cements on osseointegrated implants using Lewis rats. Twenty-two rats were distributed into 6 groups: negative control (NC) soft diet (SD), and hard diet (HD); positive control SD and HD (n = 3); Implant + bio-ceramic Cement (BC) SD and HD which included contralateral Sham sites (n = 5). Titanium implants were placed on either side of the maxillae and allowed to heal for 14 days. Later, both sides of experimental groups underwent a re-entry surgery to simulate clinical cementation. The right side received 0.60 mg of BC. At 14 days post cement application, maxillae were harvested for clinical, microtomographic, and histological evaluations. Clinical and microtomographic evaluations indicated evidence of extensive inflammation and circumferential bone resorption around BC implants in comparison to NC. Histology revealed cement particles surrounded by inflammatory infiltrate in the implant area accompanied by biofilm for SD groups. Both sides of BC indicated intensive bone resorption accompanied by signs of osteolysis when compared to NC. Cemented groups depicted significantly lower bone to implant contact when compared to NC. In conclusion, residual cement extravasation negatively impacted osseointegrated implants after re-entry surgeries.

Development and Application of Reversible and Irreversible Covalent Probes for Human and Mouse Cathepsin-K Activity Detection, Revealing Nuclear Activity

Cathepsin-K (CTSK) is an osteoclast-secreted cysteine protease that efficiently cleaves extracellular matrices and promotes bone homeostasis and remodeling, making it an excellent therapeutic target. Detection of CTSK activity in complex biological samples using tailored tools such as activity-based probes (ABPs) will aid tremendously in drug development. Here, potent and selective CTSK probes are designed and created, comparing irreversible and reversible covalent ABPs with improved recognition components and electrophiles. The newly developed CTSK ABPs precisely detect active CTSK in mouse and human cells and tissues, from diseased and healthy states such as inflamed tooth implants, osteoclasts, and lung samples, indicating changes in CTSK's activity in the pathological samples. These probes are used to study how acidic pH stimulates mature CTSK activation, specifically, its transition from pro-form to mature form. Furthermore, this study reveals for the first time, why intact cells and cell lysate exhibit diverse CTSK activity while having equal levels of mature CTSK enzyme. Interestingly, these tools enabled the discovery of active CTSK in human osteoclast nuclei and in the nucleoli. Altogether, these novel probes are excellent research tools and can be applied in vivo to examine CTSK activity and inhibition in diverse diseases without immunogenicity hazards.

Titanium corrosion products from dental implants and their effect on cells and cytokine release: A review

INTRODUCTION

Titanium is considered to be an inert material owing to the ability of the material to form a passive titanium oxide layer. However, once the titanium oxide layer is lost, it can lead to exposure of the underlying titanium substructure and can undergo corrosion.

SUMMARY

The article explores the role of titanium ions and particles from dental implants on cells, cytokine release, and on the systemic redistribution of these particles as well as theories proposed to elucidate the effects of these particles on peri-implant inflammation based on evidence from in-vitro, human, and animal studies. Titanium particles and ions have a pro-inflammatory and cytotoxic effect on cells and promote the release of pro-inflammatory mediators like cytokines. Three theories to explain etiopathogenesis have been proposed, one based on microbial dysbiosis, the second based on titanium particles and ions and the third based on a synergistic effect between microbiome and titanium particles on the host.

CONCLUSION

There is clear evidence from in-vitro and limited human and animal studies that titanium particles released from dental implants have a detrimental effect on cells directly and through the release of pro-inflammatory cytokines. Future clinical and translational studies are required to clarify the role of titanium particles and ions in peri-implant inflammation and the etiopathogenesis of peri-implantitis.

Preclinical comparison study of experimental peri-implantitis between alveolar ridge preservation and spontaneous healing sites in infected and noninfected tooth: a randomized blinded in vivo study

BACKGROUND

This study compared the progression of experimental peri-implantitis between alveolar ridge preservation (ARP) and spontaneous healing (SH) sites in infected (IT) and noninfected tooth (NIT).

METHODS

Bilateral mandibular third or fourth premolars of six beagle dogs were randomly assigned to IT and NIT groups. Before extraction, chronic dehiscence defects were created at the mesial root of mid-buccal area in IT group. Four weeks later, the mesial roots of the third and fourth premolars were extracted in all groups.ARP procedure was randomly conducted on one side of the extraction sockets using collagenated bovine bone substitutes and resorbable collagen membrane, and contralateral side was allowded spontaneous healing. After 12 weeks of healing, bone-level implants (ϕ 3.6 × 8.0 mm) were placed at the extraction sockets. Three months of ligature induced peri-implantitis and three months of spontaneous progression were allowed, with radiographs taken at each phase. Biopsies were retrieved at the implant site for histomorphometric, immunohistochemical, and polarized light-microscopic analyses.

RESULTS

Radiography demonstrated that the changes in the marginal bone level during the spontaneous progression period showed no significant differences between ARP and SH sites. Only small and/or nonsignificant differences in the progression of peri-implantitis were observed between ARP and SH sites in histomorphometric, immunohistochemical, and polarized light microscopic analyses. Additionally, the IT and NIT groups exhibited similar outcomes for most parameters.

CONCLUSION

ARP with xenogenic bone substitutes might provide similarly robust results as SH sites regarding the progression of experimental peri-implantitis, irrespective of the infected or noninfected nature of the site before tooth extraction.

Immunogenic effects of enamel matrix derivative on human alveolar ridge mucosa-derived vascular endothelial cells under lipopolysaccharide stimulation

Early peri-implant disease detection remains difficult. Enamel matrix derivative (EMD), which is used for periodontal tissue regeneration, promotes leukocyte chemotactic factor and adhesion molecule expression in vascular endothelial cells. We hypothesized that stimulating vascular endothelial cells with EMD would induce an inflammatory response in the peri-implant mucosa, enabling early peri-implant infection detection. To verify this hypothesis, we assessed the intercellular adhesion between human alveolar ridge mucosa-derived vascular endothelial cells (ARMEC) stimulated with lipopolysaccharide (LPS) and EMD and human periodontal ligament-derived vascular endothelial cells (PDLEC). Leukocyte chemotactic factors and cell adhesion molecules were investigated and we established an experimental model of peri-implant disease by stimulating ARMEC (representing the peri-implant mucosa) with Porphyromonas gingivalis-derived LPS. ARMEC and PDLEC were obtained from patients (n = 6) who visited the Nippon Dental University Niigata Hospital. The cells were divided into four subcategories, each cultured with: LPS (1 µg/mL), EMD (100 µg/mL), LPS + EMD, and pure medium. Cell viability, leukocyte chemotactic factor (interleukin-8: IL-8), adhesion molecules (intercellular adhesion molecule-1: ICAM-1), tight junction protein gene expression (zonula occludens-1: ZO-1 and Occludin), and transendothelial electrical resistance (TEER) was then determined. LPS reduced ARMEC viability, whereas simultaneous stimulation with EMD improved it. LPS and EMD stimulation enhanced IL-8 and ICAM-1 gene expression, suppressed TEER, and decreased ZO-1 and Occludin expression levels compared to that with stimulation with LPS alone. EMD stimulates leukocyte migration, increase vascular permeability, and trigger an immune response in the peri-implant mucosa, thus facilitating the early detection and treatment of peri-implant disease.

Comparative proteomics analysis of biofilms and planktonic cells of Enterococcus faecalis and Staphylococcus lugdunensis with contrasting biofilm-forming ability

Biofilms make it difficult to eradicate bacterial infections through antibiotic treatments and lead to numerous complications. Previously, two periprosthetic infection-related pathogens, Enterococcus faecalis and Staphylococcus lugdunensis were reported to have relatively contrasting biofilm-forming abilities. In this study, we examined the proteomics of the two microorganisms' biofilms using LC-MS/MS. The results showed that each microbe exhibited an overall different profile for differential gene expressions between biofilm and planktonic cells as well as between each other. Of a total of 929 proteins identified in the biofilms of E. faecalis, 870 proteins were shared in biofilm and planktonic cells, and 59 proteins were found only in the biofilm. In S. lugdunensis, a total of 1125 proteins were identified, of which 1072 proteins were found in common in the biofilm and planktonic cells, and 53 proteins were present only in the biofilms. The functional analysis for the proteins identified only in the biofilms using UniProt keywords demonstrated that they were mostly assigned to membrane, transmembrane, and transmembrane helix in both microorganisms, while hydrolase and transferase were found only in E. faecalis. Protein-protein interaction analysis using STRING-db indicated that the resulting networks did not have significantly more interactions than expected. GO term analysis exhibited that the highest number of proteins were assigned to cellular process, catalytic activity, and cellular anatomical entity. KEGG pathway analysis revealed that microbial metabolism in diverse environments was notable for both microorganisms. Taken together, proteomics data discovered in this study present a unique set of biofilm-embedded proteins of each microorganism, providing useful information for diagnostic purposes and the establishment of appropriately tailored treatment strategies. Furthermore, this study has significance in discovering the target candidate molecules to control the biofilm-associated infections of E. faecalis and S. lugdunensis.

The Effects of Ultrasonic Scaling and Air-Abrasive Powders on the Topography of Implant Surfaces: Scanning Electron Analysis and In Vitro Study

OBJECTIVES

 This in vitro study aimed to investigate the impact of bicarbonate air-abrasive powders and ultrasonic scaling with stainless steel tips on the micro- and nanotopography and roughness of three different implant-abutment junction titanium surfaces.

MATERIALS AND METHODS

 Three types of sterile and decontaminated titanium surfaces (RS, UTM, XA) were used for analysis. Nine disks per surface type were subjected to micro- and nanotopography analysis, scanning electron microscopy (SEM), roughness analysis, and fibroblast cultivation. Ultrasonic debridement and air polishing were performed on the surfaces. Human dermal fibroblasts were cultured on the surfaces for 5 days.

STATISTICAL ANALYSIS

 Data analysis adhered to ISO 25178 standards for surface texture assessment. SEM micrographs were used to reconstruct areas for extracting roughness parameters. Excel and Mex 6.0 software were utilized for quantitative and stereoscopic analysis.

RESULTS

 The study found varying effects on surface roughness posttreatment. RS Disco samples exhibited higher surface roughness compared with UTM and XA samples, both in average and nanoscale roughness. Decontamination led to increased surface roughness for all samples, particularly RS Disco. Fibroblast growth tests revealed enhanced cell network formation on decontaminated discs, possibly due to increased nanoscale roughness or the presence of bicarbonate salts.

CONCLUSION

 The study underscores the complex interplay between surface topography, microbial biofilm, and treatment efficacy in peri-implant disease management. While smoother surfaces may resist biofilm accumulation, increased nanoscale roughness postdecontamination can enhance fibroblast attachment and soft tissue integration. This dichotomy highlights the need for tailored treatment protocols that consider material-specific factors, emphasizing that successful implant therapy should balance microbial control with conducive surface characteristics for long-term osseointegration and soft tissue stability.

Quantity and Size of Titanium Particles Released from Different Mechanical Decontamination Procedures on Titanium Discs: An In Vitro Study

Complications such as peri-implantitis could ultimately affect the survival of a dental implant. The prevention and treatment of peri-implant diseases require managing bacterial biofilm and controlling environmental risks, including the presence of pro-inflammatory titanium (Ti) particles in the peri-implant niche. Objectives included the evaluation of the size and quantity of Ti particles released from moderately roughened Ti surfaces during common mechanical surface decontamination methods. One hundred and forty moderately roughened Ti discs were divided into seven groups (n = 20 per group); six groups received mechanical decontamination procedures (ultrasonic scaling (US) with a metal tip and poly-ether-ketone (PEEK) under low and medium power settings, air-polishing with erythritol powder, and Ti brush), and the control group underwent air-water spray using a dental triplex. The rinsing solution was collected for Ti mass analysis using inductively coupled plasma mass spectrometry (ICPMS), as well as for Ti particle size and count analysis under scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). US metal tip instrumentation generated 34.00 ± 12.54 μg and 34.44 ± 6.08 μg of Ti under low and medium power settings, respectively. This amount of Ti generation was significantly higher than other instrumentation methods. The mean Ti particle size of the US groups ranged from 0.89 ± 0.27 μm to 1.25 ± 0.24 μm. No statistically significant difference was found in the particle size among US groups and Ti brush group (1.05 ± 0.11 μm), except for US with the PEEK tip, where a significantly smaller mean particle diameter was found at the low power setting (0.89 ± 0.27 μm). Mechanical instrumentation can produce Ti particulates and modify the implant surfaces. US using a metal tip generated the highest amount of Ti with smaller Ti size particles compared to all other commonly used mechanical surface instrumentations. The EDS analysis confirmed Ti in PEEK US tips. It can be suggested that deterioration from the PEEK US tip and Ti brush, as observed under SEM, is an additional source of Ti release during Ti surface decontamination.

Numerical study on the three-dimensional temperature distribution according to laser conditions in photothermal therapy of peri-implantitis

PURPOSE

Dental implants have been successfully implemented as a treatment for tooth loss. However, peri-implantitis, an inflammatory reaction owing to microbial deposition around the implant, can lead to implant failure. So, it is necessary to treat peri-implantitis. Therefore, this numerical study is aimed at investigating conditions for treating peri-implantitis.

METHODS

Photothermal therapy, a laser treatment method, utilizes photothermal effect, in which light is converted to heat. This technique has advantage of selectively curing inflamed tissues by increasing their temperature. Accordingly, herein, photothermal effect on peri-implantitis is studied through numerical analysis with using Arrhenius damage integral and Arrhenius thermal damage ratio.

RESULTS

Through numerical analysis on peri-implantitis treatment, we explored temperature changes under varied laser settings (laser power, radius, irradiation time). We obtained the temperature distribution on interface of artificial tooth root and inflammation and determined whether temperature exceeds or does not exceed 47℃ to know which laser power affects alveolar bone indirectly. We defined the Arrhenius thermal damage ratio as a variable and determined that the maximum laser power that does not exceed 47℃ at the AA' line is 1.0 W. Additionally, we found that the value of the Arrhenius thermal damage ratio is 0.26 for a laser irradiation time of 100 s and 0.50 for 500 s.

CONCLUSION

The result of this numerical study indicates that the Arrhenius thermal damage ratio can be used as a standard for determining the treatment conditions to help assisted laser treatment for peri-implantitis in each numerical analysis scenario.

Micro-Computed Tomography Analysis of Peri-Implant Bone Defects Exposed to a Peri-Implantitis Microcosm, with and without Bone Substitute, in a Rabbit Model: A Pilot Study

Peri-implantitis is an inflammatory condition characterized by inflammation in the peri-implant connective tissue and a progressive loss of supporting bone; it is commonly associated with the presence of biofilms on the surface of the implant, which is an important factor in the development and progression of the disease. The objective of this study was to evaluate, using micro-CT, the bone regeneration of surgically created peri-implant defects exposed to a microcosm of peri-implantitis. Twenty-three adult New Zealand white rabbits were included in the study. Bone defects of 7 mm diameter were created in both tibiae, and a cap-shaped titanium device was placed in the center, counter-implanted with a peri-implantitis microcosm. The bone defects received a bone substitute and/or a resorbable synthetic PLGA membrane, according to random distribution. Euthanasia was performed 15 and 30 days postoperatively. Micro-CT was performed on all samples to quantify bone regeneration parameters. Bone regeneration of critical defects occurred in all experimental groups, with a significantly greater increase in cases that received bone graft treatment (p < 0.0001), in all measured parameters, at 15 and 30 days. No significant differences were observed in the different bone neoformation parameters between the groups that did not receive bone grafts (p > 0.05). In this experimental model, the presence of peri-implantitis microcosms was not a determining factor in the bone volume parameter, both in the groups that received regenerative treatment and in those that did not.

Construction of a diagnostic model based on random forest and artificial neural network for peri-implantitis

OBJECTIVES

This study aimed to reveal critical genes regulating peri-implantitis during its development and construct a diagnostic model by using random forest (RF) and artificial neural network (ANN).

METHODS

GSE-33774, GSE106090, and GSE57631 datasets were obtained from the GEO database. The GSE33774 and GSE106090 datasets were analyzed for differential expression and functional enrichment. The protein-protein interaction networks (PPI) and RF screened vital genes. A diagnostic model for peri-implantitis was established using ANN and validated on the GSE33774 and GSE57631 datasets. A transcription factor-gene interaction network and a transcription factor-micro-RNA (miRNA) regulatory network were also established.

RESULTS

A total of 124 differentially expressed genes (DEGs) involved in the regulation of peri-implantitis were screened. Enrichment analysis showed that DEGs were mainly associated with immune receptor activity and cytokine receptor activity and were mainly involved in processes such as leukocyte and neutrophil migration. The PPI and RF screened six essential genes, namely, CD38, CYBB, FCGR2A, SELL, TLR4, and CXCL8. The receiver operating characteristic curve (ROC) indicated that the ANN model had an excellent diagnostic performance. FOXC1, GATA2, and NF-κB1 may be essential transcription factors in peri-implantitis, and hsa-miR-204 may be a key miRNA.

CONCLUSIONS

The diagnostic model of peri-implantitis constructed by RF and ANN has high confidence, and CD38, CYBB, FCGR2A, SELL, TLR4, and CXCL8 are potential diagnostic markers. FOXC1, GATA2, and NF-κB1 may be essential transcription factors in peri-implantitis, and hsa-miR-204 plays a vital role as a critical miRNA.

Efficacy of Biofilm Removal on the Dental Implant Surface by Sodium Bicarbonate and Erythritol Powder Airflow System

OBJECTIVE

 Peri-implantitis is a common complication in implant therapy and it is one of the main contributing factors to implant failure. This can be prevented by regular maintenance with mechanical debridement. One of the recent mechanical debridement methods is air abrasion therapy using different abrasive powders. This study aimed to evaluate the two common abrasive powders of different sizes (sodium bicarbonate and erythritol) for their biofilm cleaning efficacy on dental implant surfaces.

MATERIALS AND METHODS

 In an in vitro setting, a total of 33 implants were divided into three groups: Group 1 (n =11) = no treatment; group 2 (n = 11) = air abrasion therapy treated group using a sodium bicarbonate powder (AIRFLOW Powder Classic Comfort, EMS Electro Medical Systems, Nyon, Switzerland); and group 3 (n = 11) = air abrasion therapy treated group using an erythritol powder (AIRFLOW Powder Plus, EMS Electro Medical Systems, Nyon, Switzerland). The implants in each group were subjected to biofilm formation, and group 2 and group 3 were treated with air abrasion therapy of two different powders having different sizes with the same settings. The particle sizes were sodium bicarbonate (40 µm) and erythritol (14µm). The surface characteristics of the dental implants in three groups were studied from a digital camera and under the scanning electron microscope at different magnifications. The comparison of biofilm-removal efficacy between the three groups was performed by using a one-way analysis of variance with post-hoc Dunnett's T3 test. A p-value less than 0.05 was chosen to indicate statistical significance.

RESULTS

 There were no statistical differences (p > 0.05) between the two powder-treated groups for the biofilm cleaning efficacy. However, both groups showed significantly better biofilm-cleaning efficacy than the control group (p < 0.05).

CONCLUSION

 This suggests that both powders are effective in removing biofilm from the implant surface under ideal conditions. However, there was no clear distinction between the cleaning potential of the two powders, as both performed in a similar manner.

Serum TNF-α level and probing depth as a combined indicator for peri-implant disease

Peri-implant disease (PID) is a general term for inflammatory diseases of soft and hard tissues that occur around implants, including peri-implant mucositis and peri-implantitis. Cytokines are a class of small molecule proteins, which have various functions such as regulating innate immunity, adaptive immunity, and repairing damaged tissues. In order to explore the characteristics and clinical significance of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and tumor growth factor (TGF)-β1 expression levels in serum of patients with peri-implant disease, 31 patients with PID and 31 patients without PID were enrolled. The modified plaque index (mPLI), modified sulcus bleeding index (mSBI), and peri-implant probing depth (PD) were recorded. The levels of serum TNF-α, IL-6, IL-10, and TGF-β1 were detected by ELISA. TNF-α, mPLI, mSBI, and PD levels were significantly higher in the PID group. TGF-β1 levels were significantly higher in the control group. There was a significant positive correlation between TNF-α and mPLI, mSBI, and PD. TGF-β1 was negatively associated with TNF-α, mPLI, mSBI, and PD. Multiple logistic regression analysis showed that TNF-α and PD were risk factors for the severity of PID. The receiver operating curve analysis showed that high TNF-α levels (cut-off value of 140 pg/mL) and greater PD values (cut-off value of 4 mm) were good predictors of PID severity with an area under the curve of 0.922. These results indicated that TNF-α and PD can be used as a biological indicator for diagnosing the occurrence and progression of PID.

Indian Society of Periodontology Good Clinical Practice Recommendations for Peri-implant Care

Current implant therapy is a frequently employed treatment for individuals who have lost teeth, as it offers functional and biological advantages over old prostheses. Concurrently, active exploration of intervention strategies aims to prevent the progression of peri-implant diseases and manage the existing peri-implant tissue damage. Indian Society of Periodontology has recognized the need for systematic documents to update the everyday clinical practice of general dental practitioners and has provided evidence-based consensus documents, namely good clinical practice recommendations from time to time to raise the oral health-related awareness and standards of oral health-care delivery across the country. The current clinical practice recommendations focused on peri-implant care to bridge the gap between academic theory and clinical practice by compiling evidence-based suggestions for preventing and treating peri-implant diseases. Twenty-eight subject experts across the country prepared these recommendations after a thorough literature review and group discussions. The document has been prepared in three sections covering peri-implant health and maintenance, peri-implant mucositis, and peri-implantitis. It will be a quick and concise reference for oral implant practitioners in patient management. The guidelines provide distinct definitions, signs, and symptoms, treatment required; recall visit specifications for plausible clinical case situations, and home-care recommendations regarding maintaining peri-implant health. The document advocates combined efforts of oral implant practitioners and the population at large with evidence-based, integrated, and comprehensive peri-implant care. By providing accessible, applicable guidance, these guidelines would empower dental professionals to uphold the well-being of implant patients and ensure the long-term success of implant therapy.

Correlation of C-Reactive Protein and Severity of Peri-Implant Diseases

Peri-implant disease pathogenesis is similar to periodontal disease pathogenesis resulting in production of pro-inflammatory mediators. These mediators are released during the inflammation phase, among which C-reactive protein (CRP) is one of the acute phase reactants. The aim of the study was to correlate the levels of CRP with the severity of peri-implant diseases. The present observational study was carried out from June 2022 to December 2022 in the Department of Implantology, Saveetha Dental College and Hospitals, Chennai, India. A total of 60 patients with peri-implant health (n = 20), peri-mucositis (n = 20) and peri-implantitis (n = 20) were enrolled. Unstimulated salivary samples were collected and subjected to latex agglutination assay for CRP analysis. CRP levels were then correlated with severity of peri-implant diseases. The mean CRP level in peri-implant health, peri-implant mucositis, peri-implantitis were 0.25 ± 0.36 mg/dl, 3.56 ± 0.85 mg/dl and 5.07 ± 0.74 mg/dl, respectively. Pearson correlation coefficient analysis revealed a strong positive correlation between CRP and peri-implant parameters suggesting that the CRP level increased as the severity of peri-implant disease increased. CRP level increases with severity of peri-implant diseases and there exists a positive correlation between CRP level and peri-implant parameters. Therefore, CRP can be used as a diagnostic marker for peri-implant diseases.

Comparative Assessment of Catalase Levels in Peri-Implant Health and Disease

Peri-implant disease pathogenesis is similar to periodontal disease pathogenesis resulting in production of pro-inflammatory mediators. These mediators alter the redox balance leading to decrease in antioxidants, among which catalase is one of the enzymatic antioxidants. The aim of the study was to compare the levels of catalase in peri-implant health and disease. The present observational study was carried out from June 2022 to December 2022 in the Department of Implantology, Saveetha Dental College and Hospitals, Chennai, India. A total of 60 patients with peri-implant health (Group 1; n = 20), peri-implant mucositis (Group 2; n = 20) and peri-implantitis (Group 3; n = 20) were enrolled. Unstimulated salivary samples were collected and subjected to ELISA for catalase analysis. Catalase levels were then compared between the groups using ANOVA. The mean catalase level in peri-implant health, peri-implant mucositis, peri-implanti-tis were 25.07 ± 0.44 U/mL, 18.5 6 ± 0.65 U/mL, and 11.25 ± 0.76 U/mL respectively. The difference between the three groups were statistically significant (P < 0.05). Catalase level decreases with severity of peri-implant diseases. Therefore, catalase can be used as a diagnostic marker for peri-implant diseases.

Influence of crestal and sub-crestal implant position on development of peri-implant diseases: a 5-year retrospective analysis

OBJECTIVES

The aim of the present study was to evaluate the influence of crestal and subcrestal implant position on development of peri-implant diseases.

MATERIALS AND METHODS

The study was designed as a retrospective clinical and radiographic analysis. Implant-supported fixed dental prostheses were allocated in two groups: with the shoulder (i) placed in sub-crestal level and (ii) placed at bone level. For each patient, the following clinical variables were assessed: FMPS, FMBS, PlI, BOP, and PD. After prothesis delivery, an intraoral radiograph was obtained; this exam was performed also at 5 years of observation period.

RESULTS

No statistically significant difference was found in terms of FMPS and FMBS at baseline and after 5 years follow-up (P < 0.05). A statistically significant difference was assessed between PD of control group and test group (P = 0.042). Patient-based analysis showed a 25.6% of peri-implant mucositis and 32.6% of peri-implantitis for implants placed with the shoulder in crestal position, while for implants inserted in sub-crestal position the percentage of peri-implant-mucositis and peri-implantitis were 19%; no statistically significant difference was found between groups after 5 years (P < 0.05).

CONCLUSIONS

Within the limitation of the present study, the clinical and radiographic outcomes showed that the percentage of peri-implant mucositis and peri-implantitis was not statistically significant for both groups after 5 years follow-up.

CLINICAL RELEVANCE

The outcomes of present study clinically demonstrated that a deep position of implant shoulder did not provide any benefits. On the contrary, it may be considered a possible risk indicator for implant diseases.

Electron microscopic analysis of necrotic bone and failed implant surface in a patient with medication-related osteonecrosis of the jaw

BACKGROUND

Bisphosphonates (BP), a commonly used medication for various bone diseases, have been known to have severe complications such as bisphosphonate-related osteonecrosis of the jaw (BRONJ). Failure of dental implants has also been found in patients with medication-related osteonecrosis of the jaw (MRONJ). In this study, we analyzed the necrotic bone tissues and the surface of the failed implants removed from the jaw in patients treated with BPs and antiresorptive agents.

RESULTS

Chronic inflammatory cells with collagen and fibrous tissues and bone sequestrum were shown at 5.0 × , 10.0 × , 20.0 × , and 40.0 × magnified histologic sections in the bone and fibrotic scar tissues removed from patients with MRONJ due to osteonecrosis. Hardened bone tissues with microcracked bony resorbed lacunae were observed in SEM. Unlike the previously published comparative data where immune cells, such as dendritic cells, were found in the failed implant surface, these immune cells were not identified in the BRONJ-related peri-implantitis tissues through the TEM investigations. Furthermore, EDS revealed that in addition to the main titanium element, gold, carbon, oxygen, calcium, phosphorus, silicon, and sulfur elements were found.

CONCLUSION

Hardened bone tissues with microcracked bony resorbed lacunae were observed in the SEM findings, which were considered as the main characteristic of the osteonecrosis of the jaw. Immune cells, such as dendritic cells were not identified in the TEM. EDS showed that in addition to the main titanium element, gold, carbon, oxygen, calcium, phosphorus, and silicon elements were found. Furthermore, it was revealed that sulfur was found, which was considered to be one of the complicated causes of implant failure in patients with BRONJ.

Fit and forget: The future of dental implant therapy via nanotechnology

Unlike orthopedic implants, dental implants require the orchestration of both osseointegration at the bone-implant interface and soft-tissue integration at the transmucosal region in a complex oral micro-environment with ubiquitous pathogenic bacteria. This represents a very challenging environment for early acceptance and long-term survival of dental implants, especially in compromised patient conditions, including aged, smoking and diabetic patients. Enabling advanced local therapy from the surface of titanium-based dental implants via novel nano-engineering strategies is emerging. This includes anodized nano-engineered implants eluting growth factors, antibiotics, therapeutic nanoparticles and biopolymers to achieve maximum localized therapeutic action. An important criterion is balancing bioactivity enhancement and therapy (like bactericidal efficacy) without causing cytotoxicity. Critical research gaps still need to be addressed to enable the clinical translation of these therapeutic dental implants. This review informs the latest developments, challenges and future directions in this domain to enable the successful fabrication of clinically-translatable therapeutic dental implants that would allow for long-term success, even in compromised patient conditions.

Influence of Bariatric Surgery on Oral Microbiota: A Systematic Review

The study aims to systematically review the available literature to evaluate the changes in oral microbiota in patients after bariatric surgery (BS) and correlates these alterations in microorganisms with common oral manifestations. Relevant Electronic databases were systematically searched for indexed English literature. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed for framework designing, application, and reporting of the current systematic review. The focused PICO question was: "Is there any change in oral microbiota (O) of patients (P) who underwent BS (I) when compared with non-BS groups (C)?' Seven articles were selected for qualitative synthesis. On application of the National Institutes of Health (NIH) quality assessment tool, six studies were found to be of fair quality and one was of good quality. All the seven included studies evaluated the effect of BS on oral microbiota in humans. The outcomes of this review suggest that considerable changes take place in oral microbiota after BS which can be correlated with common oral manifestations. These changes are mainly due to the indirect effect of BS and may vary with the individuals. Due to variations in the included studies, it is difficult to proclaim any persistent pattern of oral microbiota found after BS.

Investigation of periodontal status and bacterial composition aroundmini-implants

INTRODUCTION

Mini-implants are now widely used in orthodontic treatment. Soft-tissue inflammation around the mini-implant is an important factor affecting its stability. This study aimed to investigate the periodontal status and the bacterial composition around mini-implants.

METHODS

A total of 79 mini-implants in 40 patients (aged 18-45 years) were evaluated in this study. The mini-implant probing depth (mPD), mini-implant gingival sulcus bleeding index (mBI), mini-implant plaque index (mPLI), and the composition of the supragingival and subgingival plaque around the mini-implants were recorded. After Congo red staining, the bacteria were classified and counted under a light microscope.

RESULTS

The mPLI and mBI around mini-implants in the infrazygomatic crest were higher than those in the buccal shelf and interradicular area. The mPD was higher on the coronal site of the mini-implant than on the mesial, distal, and apical sites in the infrazygomatic crest. The mPLI around the mini-implant was positively correlated with the mBI, and the mBI was positively correlated with the mPD. The supragingival and subgingival bacterial composition around the mini-implants was similar to that of natural teeth. Compared with supragingival bacterial composition, the subgingival bacteria of mini-implants had a significantly lower proportion of cocci and a higher proportion of bacilli and spirochetes.

CONCLUSIONS

The bacteria composition of the plaque and the location are important factors in the inflammation around mini-implants. Similar to natural teeth, mini-implants require health maintenance to prevent inflammation of the surrounding soft tissue and maintain stability.

Nonsurgical cleaning potential of deep-threaded implants and titanium particle release: A novel in vitro tissue model

OBJECTIVES

To measure the efficiency of three cleaning modalities on two implant designs with similar diameters but different thread depths as well as the presence of titanium particles.

METHODS

Sixty dyed implants (30 × 4.8 apically tapered (ATAP) and 30 × 5.0 fully tapered (FTAP)) were fixed in plastic models. The horizontal bone defects were surrounded with porcine soft tissue. Three instrumentation modalities were used to clean for 150 s: Curette (CUR), ultrasonic scaler (US), and air powder waterjet device (APWJ) with erythritol powder. Afterward, implants were photographed and scanning electron microscopic (SEM) images were taken. Titanium in the soft tissues was quantified in dissolved samples and histologically confirmed.

RESULTS

For ATAP and FTAP implants, the percentage of the cleaned surface was 26.4 ± 3.0 and 17.1 ± 2.4% for CUR, 33.7 ± 3.8% and 28.1 ± 2.3% for US, and 45.5 ± 4.1% and 24.7 ± 3.8% for APWJ, respectively. SEM images showed significant implant surface changes, especially after instrumentation with CUR and US, whereas APWJ had little to no effect. Most titanium residues were found after cleaning ATAP implants with CUR (152.0 ± 75.5), followed by US (89.5 ± 73.8) and APWJ (0.3 ± 0.8). For the FTAP implants, respective values accounted for 129.5 ± 58.6 μg and 67.0 ± 14.4 μg for CUR and US, respectively. No titanium residues were detected on ATAP with APWJ.

CONCLUSION

Based on in vitro data, erythritol-powered APWJ still appears to be the most efficient and gentle cleaning method. All three instruments, however, were found to have unprocessed areas depending on different implant designs, hence, clinical relevance for non-surgical approaches remains challenging and warrants further improvement.

Graphene and its derivatives: "one stone, three birds" strategy for orthopedic implant-associated infections

Orthopedic implants provide an avascular surface for microbial attachment and biofilm formation, impeding the entry of immune cells and the diffusion of antibiotics. The above is an important cause of dental and orthopedic implant-associated infection (IAI). For the prevention and treatment of IAI, the drawbacks of antibiotic resistance and surgical treatment are increasingly apparent. Due to their outstanding biological properties such as biocompatibility, immunomodulatory effects, and antibacterial properties, graphene-based nanomaterials (GBNs) have been applied to bone tissue engineering to deal with IAI, and in particular have great potential application in drug/gene carriers, multi-functional platforms, and coating forms. Here we review the latest research progress and achievements in GBNs for the prevention and treatment of IAI, mainly including their biomedical applications for antibacterial and immunomodulation effects, and for inducing osteogenesis. Furthermore, the biosafety of graphene family materials in bone tissue regeneration and the feasibility of clinical application are critically analyzed and discussed.

Assessment of the biofilm-forming ability on solid surfaces of periprosthetic infection-associated pathogens

Biofilm formation is one of the leading causes of complications after surgery in clinical settings. In this study, we profiled the biofilm-forming ability of various periprosthetic infection-associated pathogens on medically relevant surfaces, polystyrene (PS) and titanium (Ti). We also explored how a specific environmental stressor, epigallocatechin gallate (EGCG), affected biofilm formation. First, Congo red tests revealed that all microorganisms formed biofilms within 72 h. Then, the amounts of biofilm formation on PS at 24, 48 and 72 h and also on a Ti plate for 72 h were determined. Some microbes preferred one surface over the other, whereas other microbes formed consistent levels of biofilm regardless of the surface material. Staphylococcus lugdunenensis was the most potent, while Enterococcus faecalis and Staphylococcus aureus were the weakest. Bacterial adhesion to hydrocarbon (BATH) tests indicated that the biofilm-forming abilities were not directly correlated with cell surface hydrophobicity (CSH). Finally, an external signal, EGCG, was applied to challenge the biofilm formation of each microorganism. EGCG regulated each microorganism's ability differently, though the change was consistent across surfaces for most pathogens. This study can help a better understanding of a broad spectrum of periprosthetic infection-associated pathogens by relative comparison of their biofilm-forming abilities.

Peri-Implantitis: A New Definition Proposal Based on Unnatural Spatial Arrangement and Late Mechanical Coupling between Two Cortical Bone Layers during Osseointegration Phase: Part I

Scientists have been speculating for three decades about the reasons for the occurrence of peri-implantitis around dental implants. Many theories have been proposed since the beginning of 1990. Since then, the dental profession has been exposed to a vast number of peri-implantitis cases, whereas the “disease” had been unknown before this time. However, the situation has not improved because we focus more on how to treat the problem instead of trying to understand it completely. The aim of this paper is to present a purely bone-based explanation for the beginning of the “bone loss” process around already “osseointegrated” implants. Conclusion: There are a number of possible chain reactions of physiological bone response to dental implants which may explain the occurrence of peri-implantitis. Bacteria and “immunological reactions” may not be the main causes of this disease. In the first part, the authors present the principles of bone biology and physiology based on the theories of Donath, Jansen and Frost and transfer them to the field of implantology. They describe the stages of “osseointegration”, explaining the subsequent changes in the bone at the implant–bone interface.

Effects of titanium dioxide microparticles and nanoparticles on cytoskeletal organization, cell adhesion, migration, and proliferation in human gingival fibroblasts in the presence of lipopolysaccharide

BACKGROUND AND OBJECTIVE

Titanium wear particles may participate in the etiology of peri-implantitis. However, the influence of titanium wear particles on biological behavior of human gingival fibroblasts (HGFs) in the presence of LPS is still not clear. The present study demonstrated the effects of titanium dioxide micro- and nanoparticles (TiO₂  MPs and NPs) on HGF cell viability, cytoskeletal organization, adhesion, migration, and proliferation in vitro, and LPS was used to mimic the in vivo condition.

METHODS

Primary HGFs were treated with TiO₂ MPs (primary particle size <5 μm, 0.1 mg/ml) and NPs (primary particle size <100 nm, 0.1 mg/ml) with or without 1 μg/ml LPS. The effects of TiO₂ MPs and NPs on HGFs cell viability was measured by CCK-8 assay. The proliferation of HGF was detected by Ki67 nuclear staining. The confocal laser scanning microscope (CLSM) was used to detect the internalization of TiO₂ MPs and NPs in HGFs as well as the arrangement of F-actin, vinculin, and vimentin organization. Wound healing assay and transwell assay were performed to measure the migration of HGFs induced by TiO₂ MPs and NPs. Cell adhesion was measured using fibronectin-coated plates. The relative mRNA and protein expression of adhesion relative protein such as focal adhesion kinase (FAK), fibronectin (FN), and type I collagen (COL1) were measured using quantitative RT-PCR and western blot analysis. One-way analysis of variance (ANOVA) and Student's t-test were used to analyze the statistical significance, and p < .05 was considered statistically significant.

RESULTS

TiO₂ NPs significantly inhibited HGF cell viability, proliferation, and migration compared with TiO₂ MPs group and control group. Compared with control group (2.64 ± 0.09), the mean absorbance of the cells in 1 mg/ml TiO₂ MPs group and 0.25 mg/ml TiO₂ NPs group were significantly decreased to 1.93 ± 0.33 (p < .05) and 2.22 ± 0.18 (p < .01), respectively. The cytoskeleton disruption was found in TiO₂ NPs group. The mRNA and protein expression were significantly downregulated by TiO₂ NPs. Furthermore, both TiO₂ NPs and MPs induced more adverse effects on HGFs in the presence of LPS.

CONCLUSION

Our results indicate that TiO₂ NPs but not TiO₂ MPs significantly disrupt the cytoskeletal organization and inhibited cell adhesion, migration, and proliferation of HGFs. However, in the presence of LPS, TiO₂ MPs, and TiO₂ NPs enhance these negative effects in HGFs. Titanium wear particles are probably involved in the initiation and progression of peri-implant diseases.

SEM-EDX Analysis of Metal Particles Deposition from Surgical Burs after Implant Guided Surgery Procedures

The preparation of the implant site in guided surgery procedure takes place without irrigation, which could lead to increased friction of the drills with the formation and release of debris or metal particles. The presence of metal particles in the peri-implant tissue could represent a trigger for macrophage activity, bone resorption processes, and consequent implant loss. According to the guided surgical protocol, the study aimed to evaluate the presence of metal particles deposited during implant site preparation. Twenty-five adult porcine ribs from the same adult individual were chosen due to their trabecular bone structure, similar to facial bones. The samples were all 8 cm (length) × 3 cm (depth) × 2 cm (width) and were further subdivided to obtain 50 elements of 4 cm × 3 cm × 2 cm. Plexiglass was used to create structures such as surgical guides so that their function could be mimicked, and the guided implant site preparation sequence could be performed with them. The drill kit used in this study is a guided surgery drill kit characterized by high wear resistance, high yield strength, and good corrosion resistance. This same kit was used 50 times in this way to prepare 50 different implant sites and evaluated at different edges and number of preparation (T0-neutral edge, T1-1 full preparation, T2-10, T3-20, T4-30, T5-40, and T6-50) by SEM-EDX to assess the presence of any metal deposition. The presence of metal residues in the implant site increased according to the cycles of use of the drills. We have observed that in the first three groups, there is no presence of metals. This is evident in groups T3 and T4. Finally, the presence of metal residues becomes significant in the study’s last two groups of samples. The study highlighted how the lack of irrigation in the work site leads the deposition of metal particles and in addition to a reduction in the efficiency of the drills, resulting in less precise cutting, altering the shape of the prepared site, and, lastly, reducing the primary stability of the implants.

Graphene for Antimicrobial and Coating Application

Graphene is a versatile compound with several outstanding properties, providing a combination of impressive surface area, high strength, thermal and electrical properties, with a wide array of functionalization possibilities. This review aims to present an introduction of graphene and presents a comprehensive up-to-date review of graphene as an antimicrobial and coating application in medicine and dentistry. Available articles on graphene for biomedical applications were reviewed from January 1957 to August 2020) using MEDLINE/PubMed, Web of Science, and ScienceDirect. The selected articles were included in this study. Extensive research on graphene in several fields exists. However, the available literature on graphene-based coatings in dentistry and medical implant technology is limited. Graphene exhibits high biocompatibility, corrosion prevention, antimicrobial properties to prevent the colonization of bacteria. Graphene coatings enhance adhesion of cells, osteogenic differentiation, and promote antibacterial activity to parts of titanium unaffected by the thermal treatment. Furthermore, the graphene layer can improve the surface properties of implants which can be used for biomedical applications. Hence, graphene and its derivatives may hold the key for the next revolution in dental and medical technology.

[Clinical and microbiological evaluation of hyaluronic acid and chlorhexidine mouthwash in the treatment of peri-implant mucositis]

OBJECTIVE

The aim of this study was to evaluate the effectiveness of hyaluronic acid and chlorhexidine mouthwash in the treatment of peri-implant mucositis.

MATERIAL AND METHODS

Clinical and microbiological studies were conducted before and 14 days, 1, 3 and 6 months after the periodontal treatment in 46 patients (144 implants with fixed dentures) with peri-implant mucositis. The patients were divided into 3 groups: test, comparison and control. Basic periodontal therapy in all groups included professional cleaning and individual oral hygiene training. Test group (15 patients) received basic periodontal therapy plus 0.20% chlorhexidine with hyaluronic acid mouthwash, the comparison group (15 patients) - basic periodontal therapy +0.05% chlorhexidine mouthwash. In control group (16 patients), treatment was limited to basic periodontal therapy only.

RESULTS

At the initial stages of observations, there was a statistically significant improvement in the clinical indices in all treatment groups (p<0.001). The use of 0.20% chlorhexidine with hyaluronic acid mouthwash revealed a higher quality of treatment. After 6 months of observation, the clinical features in patients of the control group was almost similar to the state before treatment. The patients of the test group had a more pronounced elimination of facultative and periodontal pathogens in comparison with other groups.

CONCLUSION

The use of 0.20% chlorhexidine with hyaluronic acid containing mouthwash allows the clinician to achieve a better results in the treatment of peri-implant mucositis. The evaluation the oral microflora in patients with peri-implant mucositis can be used as a prognostic criterion for the outcomes of rehabilitation.

Similarity and Potential Relation Between Periimplantitis and Rheumatoid Arthritis on Transcriptomic Level: Results of a Bioinformatics Study

Background

This bioinformatics study aimed to reveal potential cross-talk genes, related pathways, and transcription factors between periimplantitis and rheumatoid arthritis (RA).

Methods

The datasets GSE33774 (seven periimplantitis and eight control samples) and GSE106090 (six periimplantitis and six control samples) were included from the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO). A differential expression analysis (p < 0.05 and |logFC (fold change)| ≥ 1) and a functional enrichment analysis (p < 0.05) were performed. Based on this, a protein-protein interaction (PPI) network was constructed by Cytoscape. RA-related genes were extracted from DisGeNET database, and an overlap between periimplantitis-related genes and these RA-related genes was examined to identify potential cross-talk genes. Gene expression was merged between two datasets, and feature selection was performed by Recursive Feature Elimination (RFE) algorithm. For the feature selection cross-talk genes, support vector machine (SVM) models were constructed. The expression of these feature genes was determined from GSE93272 for RA. Finally, a network including cross-talk genes, related pathways, and transcription factors was constructed.

Results

Periimplantitis datasets included 138 common differentially expressed genes (DEGs) including 101 up- and 37 downregulated DEGs. The PPI interwork of periimplantitis comprised 1,818 nodes and 2,517 edges. The RFE method selected six features, i.e., MERTK, CD14, MAPT, CCR1, C3AR1, and FCGR2B, which had the highest prediction. Out of these feature genes, CD14 and FCGR2B were most highly expressed in periimplantitis and RA. The final activated pathway-gene network contained 181 nodes and 360 edges. Nuclear factor (NF) kappa B signaling pathway and osteoclast differentiation were identified as potentially relevant pathways.

Conclusions

This current study revealed FCGR2B and CD14 as the most relevant potential cross-talk genes between RA and periimplantitis, which suggests a similarity between RA and periimplantitis and can serve as a theoretical basis for future research.