Histological characteristics of advanced peri-implantitis bone defects in humans

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.

Challenges and Pitfalls of Research Designs Involving Magnesium-Based Biomaterials: An Overview

Magnesium-based biomaterials hold remarkable promise for various clinical applications, offering advantages such as reduced stress-shielding and enhanced bone strengthening and vascular remodeling compared to traditional materials. However, ensuring the quality of preclinical research is crucial for the development of these implants. To achieve implant success, an understanding of the cellular responses post-implantation, proper model selection, and good study design are crucial. There are several challenges to reaching a safe and effective translation of laboratory findings into clinical practice. The utilization of Mg-based biomedical devices eliminates the need for biomaterial removal surgery post-healing and mitigates adverse effects associated with permanent biomaterial implantation. However, the high corrosion rate of Mg-based implants poses challenges such as unexpected degradation, structural failure, hydrogen evolution, alkalization, and cytotoxicity. The biocompatibility and degradability of materials based on magnesium have been studied by many researchers in vitro; however, evaluations addressing the impact of the material in vivo still need to be improved. Several animal models, including rats, rabbits, dogs, and pigs, have been explored to assess the potential of magnesium-based materials. Moreover, strategies such as alloying and coating have been identified to enhance the degradation rate of magnesium-based materials in vivo to transform these challenges into opportunities. This review aims to explore the utilization of Mg implants across various biomedical applications within cellular (in vitro) and animal (in vivo) models.

Prevalence, risk indicators, and clinical characteristics of peri-implant mucositis and peri-implantitis for an internal conical connection implant system: A multicenter cross-sectional study

BACKGROUND

Peri-implant disease prevalence is associated with a multifactorial etiology and distinct clinical characteristics of inflammation.

METHODS

The present study aimed to assess the prevalence of peri-implant diseases, identify related risk indicators, and associate specific clinical characteristics to peri-implant biological complications in the medium term. Peri-implant diseases were classified according to established case criteria. Patients' data, implant and/or prosthetic features, and maintenance records were collected. Clinical characteristics such as bleeding on probing (BOP), suppuration (SUPP), keratinized mucosa (KM), probing depth (PD), marginal recession (MR), and modified plaque index (mPI) were recorded.

RESULTS

Ninety-nine patients with 266 implants with a mean functional duration of 30.26 months were evaluated. Peri-implant mucositis and peri-implantitis prevalence totaled to 49.5% and 15.15% (patient level), respectively. Peri-implant mucositis was associated with osteoporosis (odds ratio [OR] 6.09), age (OR 0.97), diabetes mellitus (OR 3.09), cemented-retained prosthesis (OR 3.81), and partial prosthesis (OR 2.21). Peri-implantitis was associated with osteoporosis (OR 7.74) and periodontitis (OR 2.74), cemented prosthesis (OR 10.12), partial and full arch prostheses (OR 12.35 and 19.86), implant diameter (OR 3.64), abutment transmucosal height (OR 3.39), and hygiene difficulty (OR 3.14). Furthermore, mPI score 3 (OR 3.27) and PD scores (OR 1.64) were associated with peri-implant mucositis, while mPI score 3 (OR 16.42), KM (OR 1.53), PD (OR 1.81), MR (OR 2.61), and the relationship between KM and PD (OR 0.63) were associated with peri-implantitis.

CONCLUSION

In the medium term, peri-implant diseases were correlated with factors inherent to the patient's conditions, presurgical treatment plan, and hygiene maintenance care. The knowledge of the mentioned factors and featured clinical characteristics can be crucial for disease prevention and establishment of a superior implant therapy prognosis.

Ultrastructural and immunohistochemical evaluation of hyperplastic soft tissues surrounding dental implants in fibular jaws

In reconstructive surgery, complications post-fibula free flap (FFF) reconstruction, notably peri-implant hyperplasia, are significant yet understudied. This study analyzed peri-implant hyperplastic tissue surrounding FFF, alongside peri-implantitis and foreign body granulation (FBG) tissues from patients treated at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. Using light microscopy, pseudoepitheliomatous hyperplasia, anucleate and pyknotic prickle cells, and excessive collagen deposition were observed in FFF hyperplastic tissue. Ultrastructural analyses revealed abnormal structures, including hemidesmosome dilation, bacterial invasion, and endoplasmic reticulum (ER) swelling. In immunohistochemical analysis, unfolded protein-response markers ATF6, PERK, XBP1, inflammatory marker NFκB, necroptosis marker MLKL, apoptosis marker GADD153, autophagy marker LC3, epithelial-mesenchymal transition, and angiogenesis markers were expressed variably in hyperplastic tissue surrounding FFF implants, peri-implantitis, and FBG tissues. NFκB expression was higher in peri-implantitis and FBG tissues compared to hyperplastic tissue surrounding FFF implants. PERK expression exceeded XBP1 significantly in FFF hyperplastic tissue, while expression levels of PERK, XBP1, and ATF6 were not significantly different in peri-implantitis and FBG tissues. These findings provide valuable insights into the interconnected roles of ER stress, necroptosis, apoptosis, and angiogenesis in the pathogenesis of oral pathologies, offering a foundation for innovative strategies in dental implant rehabilitation management and prevention.

Echo-intensity characterization at implant sites and novel diagnostic ultrasonographic markers for peri-implantitis

AIM

To apply high-frequency ultrasound (HFUS) echo intensity for characterizing peri-implant tissues at healthy and diseased sites and to investigate the possible ultrasonographic markers of health versus disease.

MATERIALS AND METHODS

Sixty patients presenting 60 implants diagnosed as healthy (N = 30) and peri-implantitis (N = 30) were assessed with HFUS. HFUS scans were imported into a software where first-order greyscale outcomes [i.e., mean echo intensity (EI)] and second-order greyscale outcomes were assessed. Other ultrasonographic outcomes of interest involved the vertical extension of the hypoechoic supracrestal area (HSA), soft-tissue area (STA) and buccal bone dehiscence (BBD), among others.

RESULTS

HFUS EI mean values obtained from peri-implant soft tissue at healthy and diseased sites were 122.9 ± 19.7 and 107.9 ± 24.7 grey levels (GL); p = .02, respectively. All the diseased sites showed the appearance of an HSA that was not present in healthy implants (area under the curve = 1). The proportion of HSA/STA was 37.9% ± 14.8%. Regression analysis showed that EI of the peri-implant soft tissue was significantly different between healthy and peri-implantitis sites (odds ratio 0.97 [95% confidence interval: 0.94-0.99], p = .019).

CONCLUSIONS

HFUS EI characterization of peri-implant tissues shows a significant difference between healthy and diseased sites. HFUS EI and the presence/absence of an HSA may be valid diagnostic ultrasonographic markers to discriminate peri-implant health status.

Etiology, pathogenesis and treatment of peri-implantitis: A European perspective

Peri-implantitis is a plaque-associated pathological condition occurring in tissues around dental implants. It is characterized by inflammation in the peri-implant mucosa and progressive loss of supporting bone. Over the last 30 years, peri-implantitis has become a major disease burden in dentistry. An understanding of the diagnosis, etiology and pathogenesis, epidemiology, and treatment of peri-implantitis must be a central component in undergraduate and postgraduate training programs in dentistry. In view of the strong role of European research in periodontology and implant dentistry, the focus of this review was to address peri-implantitis from a European perspective. One component of the work was to summarize new and reliable data on patients with dental implants to underpin the relevance of peri-implantitis from a population perspective. The nature of the peri-implantitis lesion was evaluated through results presented in preclinical models and evaluations of human biopsy material together with an appraisal of the microbiological characteristics. An overview of strategies and outcomes presented in clinical studies on nonsurgical and surgical treatment of peri-implantitis is discussed with a particular focus on end points of therapy and recommendations presented in the S3 level Clinical Practice Guideline for the prevention and treatment of peri-implant diseases.

Progression of experimental peri-implantitis in guided bone regeneration and pristine bone: A preclinical in vivo study

BACKGROUND

Guided bone regeneration (GBR) is the most widely used technique for overcoming the deficiency of alveolar bone. However, the progression of peri-implantitis in regenerative and pristine bone sites has not been fully investigated. The aim of this study is to compare experimental peri-implantitis around implants placed in pristine bone and GBR sites.

METHODS

Bilateral  mandibular first molars were extracted from six beagle dogs, and standardized horizontal ridge defect was simultaneously created at predetermined site in unilateral mandible. After 8 weeks, guided bone regeneration procedure was conducted at the defect site. After 16 weeks, implants (ϕ 3.6×8.0 mm) were placed at both extracted sites. This study included 3 months of active breakdown and another 3 months of spontaneous progression period. Radiographs were taken at each phase and specimens were obtained for histological, immunohistochemical, and polarized light microscopic analysis.

RESULTS

Marginal bone loss around implant did not show the significant differences between pristine bone and GBR sites during spontaneous progression period. In immunohistochemical analysis, inflammatory and immune-related cells were predominantly detected in peri-implantitis-affected area rather than unaffected area. In the polarized light microscopic analysis, substantial reductions in the amount and thickness of collagen fibers were observed in peri-implantitis-affected area compared with unaffected tissues. However, there were no significant differences in histological, immunohistochemical, polarized light microscopic outcomes between pristine bone and GBR sites.

CONCLUSION

Previous hard tissue grafting at the implant sites did not affect experimental peri-implantitis and exhibited similar radiographic, histological, immunohistochemical, and polarized light microscopic outcomes compared with those of pristine bone sites.

Soft tissue features of peri‐implant diseases and related treatment

BACKGROUND

The need for soft tissue grafting at implant sites for preventing and treating peri-implant diseases is a currently investigated and debated topic.

PURPOSE

The aim of this manuscript is to explore the inflammatory mechanisms at the peri-implant soft tissue compartment, to distinguish the structural components of the peri-implant soft tissue phenotype and their role on peri-implant health, and to appraise the clinical indications and expected outcomes of soft tissue augmentation procedures at peri-implant diseased sites.

MATERIALS AND METHODS

This narrative review depicts the inflammatory biomarkers and mediators in the peri-implant crevicular fluid utilized to diagnose peri-implant disease and that have been shown to be associated with peri-implant soft tissue phenotype modification and disease resolution. The impact of the peri-implant soft tissue phenotype, involving keratinized mucosa (KM) width, attached mucosa (AM), mucosal thickness (MT), and supracrestal tissue height (STH), on peri-implant health, esthetic, patient's comfort and disease prevention are discussed. The manuscript also illustrates the use of ultrasonography for the detection of peri-implant health/disease and the evaluation of the treatment outcomes following surgical therapies.

RESULTS

Current evidence indicates that soft tissue phenotype modification at implant sites with inadequate KM width, AM and MT can be beneficial for promoting peri-implant health and improving patient's comfort and hygiene procedures. Treatment approaches and outcomes from the available literature on soft tissue phenotype modification in combination with conventional techniques at sites with peri-implant mucositis or peri-implantitis are presented and discussed in detail.

CONCLUSIONS

Soft tissue grafting can be beneficial in preventing and treating peri-implant diseases. Clinical recommendations based on the disease, soft tissue phenotype characteristics and bone defect morphology are provided for a comprehensive hard- and soft-tissue-oriented treatment of peri-implant disease.

Impact of Smoking Habit on Peri-Implant Indicators following Different Therapies: A Systematic Review

Peri-implant disease and its treatment is becoming a major concern for clinicians as the number of implants placed each year is rising. Smoking is a common habit, and it is associated with an increased risk of developing peri-implant disease. The role of smoking in the response to peri-implant treatment has never been investigated. Searches were conducted in electronic databases to screen articles published until August 2021. The included studies had at least two groups of patients: peri-implant disease only or peri-implant disease and smoking status. Outcomes of interest included plaque index (PI), probing depth (PD), bleeding on probing (BoP), radiographic crestal bone loss (CBL), and analysis of peri-implant sulcular fluid. Seven hundred and forty-nine articles were found in the databases, only 71 articles potentially qualified. A total of seven studies with a minimum follow-up of six months were included. There is no homogeneity in the diagnosis, smoker definition and treatment proposed. All surgical and non-surgical treatment have statistically significantly different outcomes in smokers and nonsmokers. Recognizing this study’s limitations, we conclude that smoking might play a significant role on the outcome of peri-implant disease treatment. None of the proposed treatments appear to be significantly more effective.

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

To date, the term peri-implantitis has been mostly associated with bacterial or foreign body reaction as primary factors of its development. Because of this, researchers’ and clinicians’ attention regarding treatment possibilities were directed into the solutions on the basis of surface modifications, debridement, and antibiotics. After years of clinical observations and poor results in treatment of peri-implantitis, a new proposal of this condition is presented, shifting our way of thinking regarding bone and implant interactions. In the second part of the paper presenting a new definition of peri-implantitis, we focused on a biological explanation of the bone behavior at the bone–implant interface. The main conclusion is that PI is not an “infectious disease”, but rather the result of natural changes of the bone’s morphology in response to implant such as a decrease in convexity of the outer surface of the bone and subsequently a decrease in concavity of the inner bone.

Effects of implant surface mechanical instrumentation methods on peri-implantitis: An in vitro study using a circumferential bone defect model

Background/purpose

Although several mechanical and chemical debridement techniques have been reported for the management of peri-implantitis, there is no consensus on the most effective method at present. This in vitro study aimed to examine the effects of different mechanical instrumentation techniques on the debridement of hard calcified materials, which are present on the implant surface, as well as the effect of the defect morphology.

Materials and methods

From a total of 15 implants, five each were assigned to one of three decontamination groups (Rotary titanium brush [Ti], tricalcium phosphate air powder abrasive treatment [Air], and titanium ultrasonic scaler [US] groups); the exposed hydroxyapatite (HA)-coated portion was divided into three 1-mm sections (coronal, middle, and apical). The residual-HA of each portion was measured using a digital microscope.

Results

The overall percentage of residual HA coating was significantly lower in the US group than in the Ti or Air groups (p < 0.01). The percentage of residual HA in the coronal portion was significantly lower in the Ti and US groups than in the Air group (p < 0.05 and p < 0.01, respectively). The percentage of residual HA in the middle portion was significantly lower in the US group than in the Air group (p < 0.01). The percentage of residual HA in the apical portion was significantly lower in the Ti group than in the Air or US groups (p < 0.01).

Conclusion

Ti and US were more effective for shallow defects, whereas US was more effective for deeper defects.

Pilot Study of Use of Nitric Oxide in Monitoring Multiple Dental Foci in Oral Cavity—A Case Report

Background: The most common cause of implant loss and deteriorating restoration aesthetics is infection and chronic inflammation of the tissues around the implants. Inflammation in the oral cavity, confirmed by clinical and histopathological examination and determination of exhaled nitric oxide, is a situation which may cause the complications on the whole human body. Elimination of the patology in the oral cavity in some cases is the only resonable treatment. The aims and objectives of our work is to present a gradual treatment of advanced infalmmation and present huge reduction stamp of inflammation measured with marker nitric oxide (NO) in exhaled air. Materials and Methods: Simple treatment containing elimantion of pathology in the oral cavity was conducted. Patient that came to the dental practice suffered from the inflammation caused by lack of proper hygiene. First aid in this situation was to eliminate the inflammation which may affect negatively for general health. At first visit full hygienization was performed, at the second visit roots of abutment teeth and implants were removed under local anesthesia along with cystic changes. Results: The hygiene precedures and extraction of the unsteady inflammationprosthetic restorations significantly decreased the level of NO in exhaled air. Conclusions: During the examination of the patient coming to the dental practice great attention should be paid to the coexistence of pathologies related to the oral cavity. Omission of a dental examination and possible elimination of odontogenic foci may affect the implication of the results of general diagnostics and subsequent treatment. Measuring the level of NO on exhaled air seems to be useful diagnostic method.

Histopathological characterization of peri-implant diseases: A systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review of the inflammatory elements in peri-implantitis (PI) and peri-implant mucositis (PM) in comparison with healthy peri-implant tissues (HI) and periodontal disease.

DESIGN

The PubMed, Embase, Web of Science, and Scopus databases were searched up to December 2020. English articles that evaluated human soft tissue biopsies of PI or PM were included. Values reported for the surface area of the infiltrated connective tissue (ICT) were pooled using the random-effect model meta-analysis to estimate the mean (95% CI).

RESULTS

A total of 33 articles were included. Of 30 studies on PI, the majority evidenced significantly increased vascularization and inflammatory cell counts dominated by plasma cells in PI compared with HI. Studies that compared PI with chronic periodontitis primarily reported more severe inflammatory infiltrates in PI. This was confirmed by the meta-analysis results since the surface area of the ICT was significantly larger in PI (p < 0.001). Only seven studies analyzed the PM lesions and reported increased inflammatory infiltrates and vascularization in PM compared with HI. Based on the meta-analysis results, the surface area of the ICT was 3.00 [1.50, 4.51] mm ² in PI and 0.23 [0.02, 0.44] mm ² in PM lesions. Based on the available evidence, presence of foreign body particles considerably increased the inflammatory infiltrate; however, smoking did not have a significant effect.

CONCLUSIONS

There was controversy regarding the prevalence of various inflammatory cell types in peri-implant diseases; however, a considerably high ICT surface area in PI indicates the aggressive nature of the disease.

Consequences of Peri-Implant Bone Loss in the Occlusal Load Transfer to the Supporting Bone in terms of Magnitude of Stress, Strain, and Stress Distribution: A Finite Element Analysis

Methods

Three models of a single internal connection bone level-type implant inserted into a posterior mandible bone section were constructed using a 3D finite element software: one control model without marginal bone loss and two test models, both with a circumferential peri-implant bone defect, one with a 3 mm high defect and the other one 6 mm high. A 150 N static load was tested on the central fossa at 6° relative to the axial axis of the implant.

Results

The results showed differences in the magnitude of strain and stress transferred to the bone between models, being the higher strain found in the trabecular bone around the implant with greater marginal bone loss. Stress distribution differed between models, being concentrated at the cortical bone in the control model and at the trabecular bone in the test models.

Conclusion

Marginal bone loss around dental implants under occlusal loading influences the magnitude and distribution of the stress transferred and the deformation of peri-implant bone, being higher as the bone loss increases.

Factors Influencing Marginal Bone Loss around Dental Implants: A Narrative Review

Implant supported dental prostheses are increasingly used in dental practice. The aim of this narrative review is to present the influence of transmucosal surface of prosthetic abutment and implant on peri-implant tissue. The article describes causes of bone loss around the dental implant. Moreover, properties of different materials are compared and discussed. The advantages, disadvantages, and biomechanical concept of different implant-abutment connections are presented. The location of connections in relation to the bone level and the influence of microgap between the abutment and implant are described. Additionally, the implant abutments for cemented and screwed prosthetic restorations are compared. The influence of implant and abutment surface at the transmucosal level on peri-implant soft tissue is discussed. Finally, the biological aspect of abutment-implant connection is analyzed.

Macrophage polarization in peri-implantitis lesions

OBJECTIVES

To immunohistochemically characterize and correlate macrophage M1/M2 polarization status with disease severity at peri-implantitis sites.

MATERIALS AND METHODS

A total of twenty patients (n = 20 implants) diagnosed with peri-implantitis (i.e., bleeding on probing with or without suppuration, probing depths ≥ 6 mm, and radiographic marginal bone loss ≥ 3 mm) were included. The severity of peri-implantitis was classified according to established criteria (i.e., slight, moderate, and advanced). Granulation tissue biopsies were obtained during surgical therapy and prepared for immunohistological assessment and macrophage polarization characterization. Macrophages, M1, and M2 phenotypes were identified through immunohistochemical markers (i.e., CD68, CD80, and CD206) and quantified through histomorphometrical analyses.

RESULTS

Macrophages exhibiting a positive CD68 expression occupied a mean proportion of 14.36% (95% CI 11.4-17.2) of the inflammatory connective tissue (ICT) area. Positive M1 (CD80) and M2 (CD206) macrophages occupied a mean value of 7.07% (95% CI 5.9-9.4) and 5.22% (95% CI 3.8-6.6) of the ICT, respectively. The mean M1/M2 ratio was 1.56 (95% CI 1-12-1.9). Advanced peri-implantitis cases expressed a significantly higher M1 (%) when compared with M2 (%) expression. There was a significant correlation between CD68 (%) and M1 (%) expression and probing depth (PD) values.

CONCLUSION

The present immunohistochemical analysis suggests that macrophages constitute a considerable proportion of the inflammatory cellular composition at peri-implantitis sites, revealing a significant higher expression for M1 inflammatory phenotype at advanced peri-implantitis sites, which could possibly play a critical role in disease progression.

CLINICAL RELEVANCE

Macrophages have critical functions to establish homeostasis and disease. Bacteria might induce oral dysbiosis unbalancing the host's immunological response and triggering inflammation around dental implants. M1/M2 status could possibly reveal peri-implantitis' underlying pathogenesis.

Nanointeraction: The profound influence of nanostructured and nano-drug delivery biomedical implant surfaces on cell behavior

Nanostructured surfaces feature promising biological properties on biomaterials attracting large interest at basic research, implant industry development, and bioengineering applications. Thou, nanoscale interactions at a molecular and cellular level are not yet completely understood and its biological and clinical implications need to be further elucidated. As follows, the aim of this comprehensive review was to evaluate nanostructured surfaces at biomedical implants focusing on surface development, nanostructuration, and nanoengineered drug delivery systems that can induce specific cell interactions in all relevant aspects of biological, reparative, anti-bacterial, anti-inflammatory and clinical processes. The methods and the physio-chemical properties involved in nanotopography performance, the main cellular characteristics involved at surface/cell interaction, and a summary of results and outlooks reported in studies applying nanostructured surfaces and nano-drug delivery systems is presented. The future prospects and commercial translation of this developing field, particularly concerning multifunctional nanostructured surfaces and its clinical implications are further discussed. At a cellular level, nanostructured biomedical implant surfaces can enhance osteogenesis by targeting osteoblasts, osteocytes, and mesenchymal cells, stimulate fibroblast/epithelial cells proliferation and adherence, inhibit bacterial cell proliferation and biofilm accumulation, and act as immune-modulating surfaces targeting macrophages and reducing pro-inflammatory cytokine expression. Moreover, several methodological options to create drug-delivery systems on metallic implant surfaces are available, however, the clinical translation is yet incomplete. The efficiency of which nanostructured/nano-delivery surfaces may target specific cell interactions and favor clinical outcomes needs to be further elucidated in pre-clinical and clinical studies, along with engineering solutions for commercial translation and approval of controlling agencies.