Basis of bone metabolism around dental implants during osseointegration and peri-implant bone loss

A forecasting model for suitable dental implantation in canine mandibular premolar region based on finite element analysis

In recent years, dental implants have become a trend in the treatment of human patients with missing teeth, which may also be an acceptable method for companion animal dentistry. However, there is a gap challenge in determining appropriate implant sizes for different dog breeds and human. In this study, we utilized skull computed tomography data to create three-dimensional models of the mandibles of dogs in different sizes. Subsequently, implants of various sizes were designed and subjected to biomechanical finite element analysis to determine the optimal implant size. Regression models were developed, exploring the relationship between the average weight of dogs and the size of premolar implants. Our results illustrated that the regression equations for mean body weight (x, kg) and second premolar (PM2), third premolar (PM3), and fourth premolar (PM4) implant length (y, mm) in dogs were: y = 0.2785x + 7.8209, y = 0.2544x + 8.9285, and y = 0.2668x + 10.652, respectively; the premolar implant diameter (mm) y = 0.0454x + 3.3506, which may provide a reference for determine suitable clinical implant sizes for dogs.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Risk factors of bone loss after Prestige-LP cervical disc arthroplasty

PURPOSE

Cervical disc arthroplasty (CDA) is widely employed for patients diagnosed with cervical degenerative disc disease (CDDD). Postoperative bone loss (BL) represents a radiological alteration that is a relatively novel consideration in the realm of CDA. This study endeavors to examine the risk factors associated with BL following CDA, aiming to elucidate the underlying mechanisms and the impact of BL on surgical outcomes.

METHODS

A retrospective study was undertaken, encompassing consecutive patients subjected to one-level CDA, two-level CDA, or two-level hybrid surgery (HS) for the treatment of CDDD at our institution. Patient demographic and perioperative data were systematically recorded. Radiological images obtained preoperatively, at 1-week post-operation, and during the last follow-up were collected and evaluated, following with statistical analyses.

RESULTS

A total of 295 patients and 351 arthroplasty segments were involved in this study. Univariate logistic regressions indicated that age ≥ 45 years and two-level HS was associated with lower risk of BL; and a greater ΔDA (change of disc angle before and after surgery) was correlated with an increased risk of BL. Multivariate logistic regression determined that two-level HS and greater ΔDA were independent preventative and risk factors for BL, respectively. Further analysis revealed that severe BL significantly elevated the risk of implant subsidence compared to non-BL and mild BL.

CONCLUSIONS

This study posited bone remodeling and micromotion as potential underlying mechanisms of BL. Subsequent research endeavors should delve into the divergent mechanisms and progression observed between lower- and higher-grade BL, aiming to prevent potential adverse outcomes associated with severe BL.

Comparative Analysis of Osteoblastic Responses to Titanium and Alumina-Toughened Zirconia Implants: An In Vitro Study

INTRODUCTION

Osteoblastic responses play a crucial role in the success of oral implants. Enhanced proliferation of osteoblast cells is associated with reduced cell mortality and an increase in bone regeneration. This study aims to evaluate the osteoblastic responses following oral implantation.

MATERIALS AND METHODS

Osteoblast stem cells were harvested and subsequently cultivated using cell culture techniques. The osteoblastic phenotype of the extracted cells was confirmed by examining the extracellular matrix. Cell morphogenesis on functionalized biomaterial surfaces was assessed through indirect immunofluorescence staining. The cellular response was investigated in the presence of two types of implant materials: titanium (Ti) and alumina-toughened zirconia (ATZ). Cell viability and apoptosis were quantitatively assessed using MTT assays and flow cytometry, respectively.

RESULTS

The survival of osteoblastic lineage cells was moderately reduced post-implantation. Viability in the Ti implant group remained at approximately 86%, while in the ATZ group, it was observed at 75%, which is considered acceptable. Moreover, there was a significant disparity in cell survival between the two implant groups (p < 0.05). Analysis of apoptosis levels at various concentrations revealed that the rate of apoptosis was 3.6% in the control group and 18.5% in the ATZ group, indicating that apoptosis or programmed cell death in the ATZ-treated group had increased nearly four-fold (p < 0.05).

CONCLUSIONS

The findings of this study indicate a reduction in osteoblastic cell line survival following implant treatment, with titanium implants exhibiting superior performance in terms of cell survival. However, it was also noted that the incidence of apoptosis in osteoblast cells was significantly higher in the presence of zirconium-based implants.

Multivariate analysis of the effect of keratinized mucosa on peri-implant tissues with platform switching: A retrospective study

BACKGROUND

In recent years, platform switching implant treatment has been increasing, which is believed to minimize bone loss around the implant after placement. However, there have been no reports on the relationship between keratinized mucosa width (KMW) and bone loss and soft tissue recession in platform switching implants.

OBJECTIVE

We evaluated the effect of the KMW on the amount of bone loss and soft tissue recession around a platform switching implant retrospectively using multivariate analysis.

MATERIALS AND METHODS

This one-year retrospective study included 91 implants in 48 patients. Age, sex, a history of periodontitis, implant location, oral hygiene status, and the KMW were included as explanatory variables to evaluate bone loss (BL) and buccal gingival height (GH). Generalized estimating equations (GEEs) were used to evaluate the effect of the KMW on platform switching peri-implant tissues.

RESULTS

The mean bone loss on the mesial (ΔBLm), distal (ΔBLd), and buccal (ΔBLb) sides of the implant were 0.16 ± 0.27 mm, 0.19 ± 0.34 mm, and 0.24 ± 0.50 mm, respectively, at 1 year after superstructure placement. The mean amount of change of GH (ΔGH) on the buccal side was 0.30 ± 0.47 mm. After correcting for confounders using GEEs, the results suggested that KMW <1.5 mm was a significant factor (P < 0.001) for bone loss over time in ΔBLm, ΔBLd, and ΔBLb. In addition, for soft tissues on the buccal side, KMW <1.5 mm was a significant factor for ΔGH reduction over time (P < 0.001).

CONCLUSIONS

Keratinized mucosa width ≥1.5 mm was associated with a higher probability less hard and soft tissue recession around the platform switching implant after 1 year from superstructure placement.

The role of the general dental practitioner in the implant journey

The relationship between referring dentist and implantologist can be crucial in making the treatment journey as efficient and effective as possible for patients. There are a number of considerations to discuss to allow effective communication of options with the patient, as well as the long-term management of these cases once returned to general practice.

Single missing molar with wide mesiodistal length restored using a single or double implant-supported crown: A self-controlled case report and 3D finite element analysis

PURPOSE

Based on a self-controlled case, this study evaluated the finite element analysis (FEA) results of a single missing molar with wide mesiodistal length (MDL) restored by a single or double implant-supported crown.

METHODS

A case of a missing bilateral mandibular first molar with wide MDL was restored using a single or double implant-supported crown. The implant survival and peri-implant bone were compared. FEA was conducted in coordination with the case using eight models with different MDLs (12, 13, 14, and 15 mm). Von Mises stress was calculated in the FEA to evaluate the biomechanical responses of the implants under increasing vertical and lateral loading, including the stress values of the implant, abutment, screw, crown, and cortical bone.

RESULTS

The restorations on the left and right sides supported by double implants have been used for 6 and 12 years, respectively, and so far have shown excellent osseointegration radiographically.The von Mises stress calculated in the FEA showed that when the MDL was >14 mm, both the bone and prosthetic components bore more stress in the single implant-supported strategy. The strength was 188.62-201.37 MPa and 201.85-215.9 MPa when the MDL was 14 mm and 15 mm, respectively, which significantly exceeded the allowable yield stress (180 MPa).

CONCLUSIONS

Compared with the single implant-supported crown, the double implant-supported crown reduced peri-implant bone stress and produced a more appropriate stress transfer model at the implant-bone interface when the MDL of the single missing molar was ≥14 mm.

Signaling pathways of dental implants' osseointegration: a narrative review on two of the most relevant; NF-κB and Wnt pathways

INTRODUCTION

Cell signaling pathways are the biological reactions that control cell functions and fate. They also directly affect the body reactions to implanted biomaterials. It is well-known that dental implants success depends on a successful integration with the alveolar bone: "osseointegration" which events comprise early and later responses to the implanted biomaterials. The early events are mainly immune-inflammatory responses to the implant considered by its microenvironment as a foreign body. Later reactions are osteogenic aiming to regulate bone formation and remodeling. All these events are controlled by the cell signaling pathways in an incredible harmonious coordination.

AIM

The number of pathways having a role in osseointegration is so big to be reviewed in a single article. So the aim of this review was to study only two of the most relevant ones: the inflammatory Nuclear Factor Kappa B (NF-κB) pathway regulating the early osseointegration events and the osteogenic Wnt pathway regulating later events.

METHODS

We conducted a literature review using key databases to provide an overview about the NF-κB and Wnt cell signaling pathways and their mutual relationship with dental implants. A simplified narrative approach was conducted to explain these cell signaling pathways, their mode of activation and how they are related to the cellular events of osseointegration.

RESULTS AND CONCLUSION

NF-κB and Wnt cell signaling pathways are important cross-talking pathways that are affected by the implant's material and surface characteristics. The presence of the implant itself in the bone alters the intracellular events of both pathways in the adjacent implant's cellular microenvironment. Both pathways have a great role in the success or failure of osseointegration. Such knowledge can offer a new hope to treat failed implants and enhance osseointegration in difficult cases. This is consistent with advances in Omics technologies that can change the paradigm of dental implant therapy.

PCAT-1' s role in wound healing impairment: Mitochondrial dysfunction and bone marrow stem cell differentiation inhibition via PKM2/β-catenin pathway and its impact on implant osseo-integration

This study focused on unravelling the role of PCAT-1 in wound-healing process, particularly its impact on regenerative and osteogenic abilities of mesenchymal stem cells (MSCs). We delved into how PCAT-1 regulates mitochondrial oxidative phosphorylation (OXPHOS) and interacts with pivotal molecular pathways, especially β-catenin and PKM2, using human bone marrow-derived MSCs. MSCs were cultured under specific conditions and PCAT-1 expression was modified through transfection. We thoroughly assessed several critical parameters: MSC proliferation, mitochondrial functionality, ATP production and expression of wound healing and osteogenic differentiation markers. Further, we evaluated alkaline phosphatase (ALP) activity and mineral deposition, essential for bone healing. Our findings revealed that overexpressing PCAT-1 significantly reduced MSC proliferation, hampered mitochondrial performance and lowered ATP levels, suggesting the clear inhibitory effect of PCAT-1 on these vital wound-healing processes. Additionally, PCAT-1 overexpression notably decreased ALP activity and calcium accumulation in MSCs, crucial for effective bone regeneration. This overexpression also led to the reduction in osteogenic marker expression, indicating suppression of osteogenic differentiation, essential in wound-healing scenarios. Moreover, our study uncovered a direct interaction between PCAT-1 and the PKM2/β-catenin pathway, where PCAT-1 overexpression intensified PKM2 activity while inhibiting β-catenin, thereby adversely affecting osteogenesis. This research thus highlights PCAT-1's significant role in impairing wound healing, offering insights into the molecular mechanisms that may guide future therapeutic strategies for enhancing wound repair and bone regeneration.

Tissue engineering innovations to enhance osseointegration in immediate dental implant loading: A narrative review

The demand for efficient and accelerated osseointegration in dental implantology has led to the exploration of innovative tissue engineering strategies. Immediate implant loading reduces treatment duration and necessitates robust osseointegration to ensure long-term implant success. This review article discusses the current studies of tissue engineering innovations for enhancing osseointegration in immediate dental implant loading in the recent decade. Keywords "tissue engineering," "osseointegration," "immediate implant loading," and related terms were systematically searched. The review highlights the potential of bioactive materials and growth factor delivery systems in promoting osteogenic activity and accelerating bone regeneration. The in vivo experiment demonstrates significantly improved osseointegration in the experimental group compared to traditional immediate loading techniques, as evidenced by histological analyses and biomechanical assessments. It is possible to revolutionize the treatment outcomes and patient satisfaction in dental implants by integrating bioactive materials and growth factors.

Impact of immediate interim restoration on peri-implant tissues around immediately placed single dental implants in the esthetic region: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Immediate implant placement with an immediate interim restoration is a well-established protocol. Nevertheless, a consensus regarding the impact of immediate interim restoration on peri-implant tissues around single dental implants is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to address the research question: "Does the placement of an immediate interim restoration influence the mid-facial mucosal (MFM) marginal and interdental papilla (IDP) levels around single dental implants placed in the anterior esthetic region by using an immediate implant placement protocol?"

MATERIAL AND METHODS

A comprehensive literature search was made in the Medline/PubMed, Scopus, Cochrane, and Science Direct electronic databases for articles published in English evaluating the impact of immediate interim restoration on peri-implant tissues around single dental implants in the anterior esthetic region. The primary outcomes assessed were changes in the MFM marginal and IDP levels. Additional outcomes were marginal bone (MB) loss, esthetic outcomes involving the pink and white esthetic scores (PES and WES), implant survival rates, and patient reported outcome measures (PROMs). The risk of bias assessment was performed by using the RoB 2 tool for randomized trials and the Newcastle-Ottawa scale for nonrandomized studies. Meta-analysis was performed by using random and fixed effects model (α=.05) in the RevMan software program.

RESULTS

Sixteen studies were included that analyzed 836 single dental implants involving 823 patients. The meta-analysis showed no significant differences in implants with and without interim restoration in terms of MFM marginal level (MD=0.01; 95% CI=-1.23 to 1.25; P=.98), mesial IDP level (MD=0.12; 95% CI=-0.23 to 0.47; P=.50), distal IDP level (MD=0.20; 95% CI=-0.40 to 0.79; P=.52), and MB loss (MD=0.01; 95% CI=-0.42 to 0.43; P=.97). The systematic analysis for survival rates determined no notable difference in implants with or without an interim restoration. However, the esthetic outcomes and PROMs substantially improved with immediate interim restorations. The RoB 2 tool showed a moderate to low risk of bias, and the Newcastle-Ottawa scale indicated high-quality studies.

CONCLUSIONS

After a 12-month follow-up, immediate interim restoration had no significant impact on peri-implant soft (MFM marginal and IDP levels) and hard tissues (MB loss) around immediately placed single dental implants. Nevertheless, additional well-designed and well-implemented clinical trials with long-term follow-up periods are needed to provide more precise evidence-based recommendations.

A Mapping Review of the Pathogenesis of Peri-Implantitis: The Biofilm-Mediated Inflammation and Bone Dysregulation (BIND) Hypothesis

This mapping review highlights the need for a new paradigm in the understanding of peri-implantitis pathogenesis. The biofilm-mediated inflammation and bone dysregulation (BIND) hypothesis is proposed, focusing on the relationship between biofilm, inflammation, and bone biology. The close interactions between immune and bone cells are discussed, with multiple stable states likely existing between clinically observable definitions of peri-implant health and peri-implantitis. The framework presented aims to explain the transition from health to disease as a staged and incremental process, where multiple factors contribute to distinct steps towards a tipping point where disease is manifested clinically. These steps might be reached in different ways in different patients and may constitute highly individualised paths. Notably, factors affecting the underlying biology are identified in the pathogenesis of peri-implantitis, highlighting that disruptions to the host-microbe homeostasis at the implant-mucosa interface may not be the sole factor. An improved understanding of disease pathogenesis will allow for intervention on multiple levels and a personalised treatment approach. Further research areas are identified, such as the use of novel biomarkers to detect changes in macrophage polarisation and activation status, and bone turnover.

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

Functionalized biomimetic mineralized collagen promotes osseointegration of 3D-printed titanium alloy microporous interface

Mineralized collagen (MC) is the fundamental unit of natural bone tissue and can induce bone regeneration. Unmodified MC has poor mechanical properties and a single component, making it unable to cope with complex physiological environment. In this study, we introduced sodium alginate (SA) and vascular endothelial growth factor (VEGF) into the MC material to construct functionalized mineralized collagen (FMC) with good mechanical strength and the ability to continuously release growth factors. The FMC is filled into the pores of 3D printed titanium alloy scaffold to form a new organic-inorganic bioactive interface. With the continuous degradation of FMC, bone marrow mesenchymal stem cells (BMSCs) and vascular endothelial cells (VECs) in the surrounding environment are recruited to the surface of the scaffold to promote bone and vascular regeneration. After implanting the scaffold into the distal femoral defect of rabbits, Micro CT, histological, push-out, as well as immunohistochemical analysis showed that the composite interface can significantly promote osseointegration. These findings provide a new strategy for the development and application of mineralized collagen materials.

Less marginal bone loss around bone-level implants restored with long abutments: A systematic review and meta-analysis

The aim of this study was to investigate the biological outcomes of bone-level implants restored with long vs. short abutments, with regard to the 'one abutment at one time' protocol. The systematic search was performed in five databases: MEDLINE (PubMed), EMBASE, Web of Science, Scopus, and CENTRAL for randomized controlled trials up to January 14, 2023. Data were collected for marginal bone loss, bleeding on probing, and probing pocket depth by two reviewers. As effect size measure, mean difference (MD), and risk ratio (RR) were used for continuous and categorical outcomes, R-statistics software was used for conducting statistical analyses. For quality and certainty assessment, Risk of Bias Tool 2, ROBINS-I, and GRADE approach were used. The search resulted in 4055 records without any duplicates. After title, abstract, and full-text analysis, eight articles were found eligible for inclusion. Bone-level and platform-switched implants presented less marginal bone loss after 6 months and 1 year as well, when long abutments were used (MD 0.63, 95% CI: [-0.16; 1.42]) and (MD 0.26, 95% CI: [-0.02; 0.53]). However, subgroup analysis revealed no difference in marginal bone loss when applying 'one abutment at one time' protocol (p = 0.973). Bleeding on probing and probing pocket depth presented similarly good results in both groups without almost any differences (RR 0.97, 95% CI: [0.76; 1.23]) and (MD -0.05, 95% CI: [-1.11; 1.01]). Longer abutments on bone-level implants seem to be a favorable choice for decreasing early marginal bone loss, irrespective of connection timing.

Bioactive prosthesis interface compositing variable-stiffness hydrogels regulates stem cells fates to facilitate osseointegration through mechanotransduction

Fluid hydrogel is proper to be incorporated with rigid porous prosthesis interface, acting as a soft carrier to support cells and therapeutic factors, to enhance osseointegration. In the previous study, we innovatively utilized self-healing supramolecular hydrogel as 3D cell culture platform to incorporate with 3D printed porous titanium alloy scaffold, constructing a novel bioactive interface. However, the concrete relationship and mechanism of hydrogel stiffness influencing cellular behaviors of bone marrow mesenchymal stem cells (BMSCs) within the interface are still inconclusive. Herein, we synthesized a series of supramolecular hydrogels with variable stiffness as extracellular matrix (ECM) to enhance the osseointegration of 3D printed prosthesis interface. BMSCs exposed to stiff hydrogel received massive environmental mechanical stimulations, subsequently transducing biophysical cues into biochemical signal through mechanotransduction process. The mRNA-sequencing analysis revealed that the activated FAK-MAPK pathway played significant roles in promoting osteogenic differentiation, thus contributing to a strong osseointegration. Our work preliminarily demonstrated the relationship of ECM stiffness and osteogenic differentiation trend of BMSCs, and optimized stiffness of hydrogel within a certain range benefitting for osteogenic differentiation and prosthesis interface osseointegration, providing a valuable insight into the development of orthopaedic implants equipped with osteogenic mechanotransduction ability.

Surface-modified titanium and titanium-based alloys for improved osteogenesis: A critical review

As implantable materials, titanium, and its alloys have garnered enormous interest from researchers for dental and orthopedic procedures. Despite their success in wide clinical applications, titanium, and its alloys fail to stimulate osteogenesis, resulting in poor bonding strength with surrounding bone tissue. Optimizing the surface topology and altered compositions of titanium and titanium-based alloys substantially promotes peri-implant bone regeneration. This review summarizes the utilization and importance of various osteogenesis components loaded onto titanium and its alloys. Further, different surface-modification methods and the release efficacy of loaded substances are emphasized. Finally, we summarize the article with prospects. We believe that further investigation studies must focus on identifying novel loading components, exploring various innovative, optimized surface-modification methods, and developing a sustained-release system on implant surfaces to improve peri-implant bone formation.

How Can Imbalance in Oral Microbiota and Immune Response Lead to Dental Implant Problems?

Dental implantology is one of the most dynamically developing fields of dentistry, which, despite developing clinical knowledge and new technologies, is still associated with many complications that may lead to the loss of the implant or the development of the disease, including peri-implantitis. One of the reasons for this condition may be the fact that dental implants cannot yield a proper osseointegration process due to the development of oral microbiota dysbiosis and the accompanying inflammation caused by immunological imbalance. This study aims to present current knowledge as to the impact of oral microflora dysbiosis and deregulation of the immune system on the course of failures observed in dental implantology. Evidence points to a strong correlation between these biological disturbances and implant complications, often stemming from improper osseointegration, pathogenic biofilms on implants, as well as an exacerbated inflammatory response. Technological enhancements in implant design may mitigate pathogen colonization and inflammation, underscoring implant success rates.

The Effect of Different Types of Collagen Membranes on Peri-Implant Dehiscence Defects

AIM

This experimental study aimed to compare the bone-implant contact (BIC) following guided bone regeneration with 3 bioabsorbable collagen membranes on peri-implant dehiscence defects.

METHODS

Forty-eight standard dehiscence defects were created in the sheep iliac bone crest, and dental implants were placed into the defects. With the guided bone regeneration technique, the autogenous graft was placed into the defect and covered with different types of membranes: Geistlich Bio-Gide, Ossix Plus, and Symbios Prehydrated were covered. One group was left without a membrane as the control group (C) by applying only an autogenous graft. After recovery periods of 3 and 6 weeks, the experimental animals were sacrificed. Histologic sections were prepared by a nondecalcified method, and BIC was examined.

RESULTS

There was no statistically important difference between groups in the third week ( P >0.05). A statistically significant difference between groups was found in the sixth week ( P <0.01). Bone-implant contact values of the C group were significantly lower than those of the Geistlich Bio-Gide and Ossix Plus groups ( P <0.05). There was no statistically significant difference between control and Symbios Prehydrated groups ( P >0.05). In all sections, osseointegration was observed, with no signs of inflammation, necrosis, or foreign body reaction.

CONCLUSION

In our study, it has been concluded that the resorbable collagen membranes used in treating peri-implant dehiscence defects might affect the BIC, and the success varies according to the type of membrane used.

Effect of calcium hydrothermal treatment of zirconia abutments on human gingival fibroblasts

Zirconia materials have been increasingly used in implant rehabilitation due to their excellent physical and esthetic properties. Stable peri-implant epithelial tissue adhesion to the transmucosal implant abutment may significantly enhance the efficacy of implant long-term stability. However, it is difficult to form stable chemical or biological bindings with peri-implant epithelial tissue due to the strong biological inertia of zirconia materials. In the present study, we investigated whether calcium hydrothermal treatment of zirconia promotes sealing of peri-implant epithelial tissue. In vitro experiments were performed to analyze the effects of calcium hydrothermal treatment on zirconia surface morphology and composition by scanning electron microscopy and energy dispersive spectrometry. Immunofluorescence staining of adherent proteins, namely, F-actin and integrin β1, in human gingival fibroblast line (HGF-l) cells was performed. In the calcium hydrothermal treatment group, there was higher expression of these adherent proteins and increased HGF-l cell proliferation. An in vivo study was conducted by extracting the maxillary right first molars of rats and replacing them with mini-zirconia abutment implants. The calcium hydrothermal treatment group showed better attachment at the zirconia abutment surface, which inhibited horseradish peroxidase penetration at 2 weeks post-implantation. These results demonstrated that calcium hydrothermal treatment of zirconia improves the seal between the implant abutment and surrounding epithelial tissues, potentially increasing the long-term stability of the implant.

The Role of Caspase-11 and Pyroptosis in the Regulation of Inflammation in Peri-Implantitis

Peri-implantitis is an important cause of oral implant failure. In the past, TLR4 and TLR2 in the Toll-like family were generally considered as the key immune recognition receptors regulating peri-implantitis. However, under the guidance of this theory, there are still some unexplainable peri-implantitis symptoms. With the discovery of novel intracellular LPS receptor Caspase-11, a new understanding of inflammatory signaling and immune regulation in the development of peri-implantitis has been gained. However, the regulatory role of Caspase-11 in peri-implantitis and its crosstalk with the TLR4 pathway remain unclear. The therapeutic effect of drugs targeting Caspase-11 on peri-implantitis is still in its early stages. In view of this situation, this paper reviews the possible role of Caspase-11 in peri-implant inflammation, elaborated the entry process of LPS and the activation mechanism of Caspase-11, and analyzes the differences in Caspase-11 between commonly studied animals, mice and humans. The current research hotspots and challenges are also analyzed to provide new insights and ideas for researchers.

Corrosion Resistance of Titanium Dental Implant Abutments: Comparative Analysis and Surface Characterization

Metals subjected to the oral environment are prone to corrosion over time and this can be harmful. Metallic restoration components such as dental subgingival implant abutments are exposed to pH changes and different ions while in contact with saliva. The aim of the study was to evaluate the corrosion resistance of titanium dental implant abutments and to compare and contrast the surface characteristics of these alloys before and after corrosion. The corrosion examination (Ecorr, jcorr, OCP, polarization curve) of two implant abutments (TiDesign EV, Astra Tech, Dentsply, York, PA, USA; Individual Titanium Abutment, Apollo Implants Components, Pabianice, Poland) was performed in 0.9% NaCl and 5% HCl. Moreover, specimens were investigated using SEM-EDS before and after the corrosion test. The value of jcorr in NaCl was higher for Astra (34.2 × 10-8 ± 2.5 × 10-8 A/cm2) than for Apollo (8.8 × 10-8 ± 2.5 × 10-8 A/cm2). Whereas, in HCl, the opposite relationship was observed (Astra 2.9 × 10-4 ± 0.8 × 10-4 A/cm2 and Apollo 62.7 × 10-4 ± 9.3 × 10-4 A/cm2). An average reactive anodic current density in NaCl for Astra amounted up to ~0.2 × 10-5-1.5 × 10-5 A/cm2, while for Apollo-up to ~3.3-9.7 × 10-7 A/cm2. The composition of both alloys after corrosion in NaCl demonstrated some changes: a decrease in the Ti, and Al and an increase in oxygen content. Hence, both alloys after corrosion in HCl demonstrated some minor changes in the elemental composition. Based on the results it can be concluded that: 1. Astra and Apollo abutments revealed good corrosion resistance and a passivation layer on the surface. 2. Apollo abutments exhibited better corrosion resistance in a neutral environment, suggesting that Astra abutments were found to be more resistant to corrosion in an acidic medium.

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part I: Evolution and Optimization of 3D-Printed Scaffolds for Repair of Defects

Bone tissue regeneration is a complex process that proceeds along the well-established wound healing pathway of hemostasis, inflammation, proliferation, and remodeling. Recently, tissue engineering efforts have focused on the application of biological and technological principles for the development of soft and hard tissue substitutes. Aim is directed towards boosting pathways of the healing process to restore form and function of tissue deficits. Continued development of synthetic scaffolds, cell therapies, and signaling biomolecules seeks to minimize the need for autografting. Despite being the current gold standard treatment, it is limited by donor sites' size and shape, as well as donor site morbidity. Since the advent of computer-aided design/computer-aided manufacturing (CAD/CAM) and additive manufacturing (AM) techniques (3D printing), bioengineering has expanded markedly while continuing to present innovative approaches to oral and craniofacial skeletal reconstruction. Prime examples include customizable, high-strength, load bearing, bioactive ceramic scaffolds. Porous macro- and micro-architecture along with the surface topography of 3D printed scaffolds favors osteoconduction and vascular in-growth, as well as the incorporation of stem and/or other osteoprogenitor cells and growth factors. This includes platelet concentrates (PCs), bone morphogenetic proteins (BMPs), and some pharmacological agents, such as dipyridamole (DIPY), an adenosine A 2A receptor indirect agonist that enhances osteogenic and osteoinductive capacity, thus improving bone formation. This two-part review commences by presenting current biological and engineering principles of bone regeneration utilized to produce 3D-printed ceramic scaffolds with the goal to create a viable alternative to autografts for craniofacial skeleton reconstruction. Part II comprehensively examines recent preclinical data to elucidate the potential clinical translation of such 3D-printed ceramic scaffolds.

Five years clinical outcome of maxillary mini dental implant overdenture treatment: A prospective multicenter clinical cohort study

BACKGROUND

The long-term clinical outcome of mini dental implants (MDIs) to support an overdenture is underreported especially in severely atrophic maxillae and when installed flaplessly.

PURPOSE

The current report is a 5-years follow-up of the previously published 2- and 3-years clinical outcome of MDIs supporting a maxillary overdenture in narrow alveolar ridges. MDI survival, marginal bone level, peri-implant health, technical complications, and oral health related quality of life (OHIP) and respective changes over time are reported.

MATERIALS AND METHODS

Subjects aged 50 years or older, in need of improvement of maxillary denture retention, were included. The MDIs were 2.4 mm diameter one-piece tapered implants, Class 4 pure Titanium, and lengths 10 or 11.5 mm. Under local anesthesia, 5-6 MDIs were placed in atrophic maxillae with a free-handed flapless approach. One week postoperative the denture was adapted with a retentive soft reliner. The final prosthetic connection was established after 6 months with a metal-reinforced horse-shoe denture. Clinical outcome after 5 years was assessed with probing pocket depts (PPD), bleeding on probing (BoP), and additional cone beam computed tomography (CBCT) MDI bone level measurements were performed. Oral Health-Related Quality of Life (OHRQoL) investigated with OHIP-14 was assessed preoperative, during provisional loading, and after final prosthetic connection up to 5 years.

RESULTS

Initially, 31 patients (14 females and 17 males) with mean age 62.30 underwent treatment. In the provisional loading interval, 16 patients encountered 32/185 MDIs failures, resulting in a failure of 17.3%; 170 MDIs were functionally loaded in 29 patients. Additionally, 14 implants were lost in three patients, all of whom had had already previous failures. Reimplantation of 17 MDIs were performed during the provisional loading and 2 MDI after functional loading. After 5 years, the absolute implant failure rate was 46/204 (22.5%), corresponding to a cumulative failure rate of 23.2%. Prosthetic failure was observed in four patients due to implant loss and in two patients related to excessive one-piece implant ball attachment wear, making the 5-years prosthetic success 80.0%. The mean PPD and absence/presence of BoP for 149 implants at 5 years was 4.3 and 0.2 mm, respectively. Average mesial-distal-vestibular-palatal bone loss in the interval 2-5 years was 0.08 mm. No statistically significant difference in marginal MDI bone loss between male or female (p = 0.835), smoking and nonsmoking (p = 0.666) was observed. The five-years total measured CBCT interdental bone level (mesial and distal) correlates with the 5-years PPD (Pearson 0.434; p = 0.01). After 5 years, OHRQoL with the treatment procedure was assessed in 27/31 participants. Decreasing mean total OHIP-14 scores with improved OHRQoL, was observed in 27/31 participants, with values of 21.3 at baseline to 15.6 at the time of provisional loading which significantly (p = 0.006) decrease to 7.3 at the final prosthetic connection. The next 3-5 years further decrease was observed with 6.5 and 4.96, respectively.

CONCLUSIONS

Maxillary MDIs for overdentures are an accessible and acceptable treatment option. Although after 5 years between one fifth and one fourth of the MDIs were lost, prosthetic success remains 80.0% and high OHRQoL could be achieved.

Utilization of Low-Magnitude High-Frequency Vibration (LMHFV) as an Aid in Treating Peri-Implantitis: Case Presentations

Peri-implantitis is an inflammatory process initiating in the soft tissue and then progressing to the hard tissue surrounding dental implants leading to loss of osseous support and potential loss of the implant if not identified early in the process. This process initiates in the soft tissue, which become inflamed spreading to the underlying bone leading to decreases in bone density with subsequent crestal resorption and thread exposure. In the absence of treatment of the peri-implantitis, the bone loss at the osseous implant interface progresses with inflammatory mediated decrease in the bone density that moves apically, eventually leading to mobility of the implant and its failure. Low-magnitude high-frequency vibration (LMHFV) has been shown to improve bone density, stimulate osteoblastic activity, and arrest progression of peri-implantitis with improvement of the bone or graft around the affected implant with or without surgery as part of the treatment. Two cases are presented using LMHFV to augment treatment.

Evaluation of Vitamin D-enriched Bone Graft in Surgically-induced Critical-sized Bone Defects: An Experimental Study

BACKGROUND

Restoration of bone defects in the craniac vault may require the use of autografts, allografts, xenografts, or synthetic grafts. There are promising data that vitamin D may play a positive role in graft incorporation. The purpose of the present study is the evaluation of the impact of vitamin D addition to human-derived bone grafts in the healing of critical-sized bone defects in porcine skulls.

MATERIALS AND METHODS

Four identical critical-sized defects were created in the calvaria of 8 adult Landrace Large White pigs. The first defect was left blank as control, the second defect was filled with human-derived bone graft, the third defect was filled with human-derived bone graft enriched with a low concentration of vitamin D (2 mg/mL), and the fourth defect was filled with human-derived bone graft enriched with a high concentration of vitamin D (10 mg/mL). The animals were sacrificed after 12 weeks. Harvested tissue specimens were qualitatively evaluated by histology. New bone formation (bone volume/tissue volume) was quantitatively measured by histomorphometry.

RESULTS

Signs of bone formation were evident in all bone sockets. Mean values of the bone volume/tissue volume of the 4 defects were 10.91%, 11.05%, 10.40% and 10.87% respectively, at 12 weeks. In 5 animals, high concentration of vitamin D caused a significant improvement in bone formation in relation to controls. In 3 animals, a high concentration of vitamin D was associated with decreased bone formation compared with controls. No statistical difference was observed in the graft healing among the 4 graft sites ( P > 0.05).

CONCLUSIONS

The results of this study have shown that the addition of vitamin D to human-derived bone grafts does not have a significant effect on bone formation and graft incorporation in critical-sized bone defects of the porcine calvaria. Further high-quality studies are needed to fully elucidate the role of vitamin D in bone formation and bone graft union.

Effects of Zn-ZnO Core-Shell Nanoparticles on Antimicrobial Mechanisms and Immune Cell Activation

The deposition of zinc-zinc oxide nanoparticles (Zn-ZnO NPs) onto porous Ta2O5 surfaces enriched with calcium phosphate by DC magnetron sputtering was investigated to improve the surface antimicrobial activity without triggering an inflammatory response. Different sizes and amounts of Zn NPs obtained by two optimized different depositions and an additional thin carbon (C) layer deposited over the NPs were explored. The deposition of the Zn NPs and the C layer mitigates the surface porosity, increasing the surface hydrophobicity and decreasing the surface roughness. The possible antimicrobial effect and immune system activation of Zn-ZnO NPs were investigated in Candida albicans and macrophage cells, respectively. It was found that the developed surfaces displayed a fungistatic behavior, as they impair the growth of C. albicans between 5 and 24 h of culture. This behavior was more evident on the surfaces with bigger NPs and the highest amounts of Zn. The same trend was observed in both reactive oxygen species (ROS) generation and loss of C. albicans' membrane integrity. After 24 h of culture, cell toxicity was also dependent on the amount of the NPs. Cell toxicity was observed in surfaces with the highest amount of Zn NPs and with the C layer, while cells were able to grow without any signs of cytotoxicity in the porous surfaces with the lowest amount of NPs. The same Zn-dose-dependent behavior was noticed in the TNF-α production. The Zn-containing surfaces show a vastly inferior cytokine secretion than the lipopolysaccharide (LPS)-stimulated cells, indicating that the modified surfaces do not induce an inflammatory response from macrophage cells. This study provides insights for understanding the Zn amount threshold that allows a simultaneous inhibition of the fungi growth with no toxic effect and the main antimicrobial mechanisms of Zn-ZnO NPs, contributing to future clinical applications.

Comparative analysis of anchorage strength and histomorphometric changes after implantation of miniscrews in adults and adolescents: an experimental study in Beagles

OBJECTIVES

This study aimed to explore the differences in anchorage strength and histomorphometric changes in orthodontic miniscrews between adult and adolescent beagles.

MATERIAL AND METHOD

Six adult beagles and six young beagles were used as experimental subjects, and eight miniscrews were symmetrically placed in the posterior mandible of each dog. Measurement of the displacement (mm) of two adjacent miniscrews after load application was performed to compare the anchorage strength between the adult and adolescent groups. Three intravital bone fluorochromes (oxytetracycline, calcein green, xylenol orange) were administered postoperatively to mark the active bone-forming surface. Subsequently, the mineral apposition rate and bone-implant contact ratio were measured for dynamic and static histomorphometry. Finally, the expression levels of the RANKL/OPG ratio were evaluated by immunohistochemistry.

RESULTS

The average displacement of miniscrews in the adult group was significantly less than that in the adolescent group after load application. For histomorphometry analysis, the mineral exposure rate in the adolescent group was higher than that in the adult group with or without force application. In addition, more fractures and new bone formation but deceased bone-implant contact ratios were observed in the adolescent group than in the adult group. The ratio of RANKL/OPG expression increased more in the adolescent group than in the adult group.

CONCLUSION

Miniscrews do not remain in the same position as skeletal anchors, and the amount of displacement was higher in adolescent group than that in adult group, reflecting the weaker anchorage strength of miniscrews in adolescents due to the higher bone turnover rate and active bone remodelling. Therefore, it is feasible to apply orthodontic loading to the miniscrews in adult patients earlier, even immediately, but it is recommended to wait a period for the adolescents.

Is it possible to decrease the occurrence of dental implant failures through the use of preventative antibiotics?

DESIGN

The research was a randomized placebo-controlled clinical trial evaluating the use of clindamycin as a preoperative medication to prevent the dental implant.

AIM

The purpose of the study was to assess if giving a single dose of 600 mg oral clindamycin 1 h before a conventional dental implant procedure could reduce the risk of early implant failure and post-surgical complications in healthy adults.

METHODS

A clinical trial was conducted with ethical standards, utilizing a randomized, double-blind, placebo-controlled approach. Healthy adults who required a single oral implant and had no previous surgical site infection or need for bone grafting were enrolled. Before surgery, participants were given either oral clindamycin or placebo at random. A single surgeon performed all operations, and patients were observed by a trained professional on multiple postoperative days. The study considered early dental implant failure as the loss or removal of an implant. Clinical, radiological, and surgical data were analyzed statistically to identify group differences. The number of subjects needed to treat, or harm, was calculated.

RESULTS

The research involved two groups of 31 patients each: the control group and the clindamycin group. Two patients in the clindamycin group experienced implant failures (NNH = 15, p = 0.246). Three patients in the study had postoperative infections; two of them were from the placebo group, while one from the clindamycin group had an unsuccessful treatment outcome. The relative risk was 0.5, with a CI of 0.05-5.23 and an absolute risk reduction of 0.03. The confidence interval was -0.07-0.13, and the NNT was 31, with a CI of 7.2-∞ and p = 0.5. In addition, only one patient treated with clindamycin reported gastrointestinal disturbances and diarrhea.

CONCLUSIONS

There is no conclusive evidence to suggest that administering clindamycin prior to oral implant surgery in healthy adults reduces the risk of implant failure or post-surgical complications.

Early Implant Bone Loss in the Preprosthetic Phase: A Retrospective Study

Initiation of the inflammatory response begins with the surgical placement of an implant that stimulates bone remodeling. The occurrence of crestal bone loss during submerged healing affects the prognosis of an implant. Hence, this study was conducted to estimate the early implant bone loss during the preprosthetic phase on bone level implants placed equicrestally. This retrospective observational study included evaluation of crestal bone loss around 271 two-piece implants placed in 149 patients from the archived postsurgical (P1) and preprosthetic (P2) digital orthopantomographic records using MicroDicom software. The outcome was categorized based on (1) sex (male or female), (2) time of implant placement (immediate [I] vs conventional [D]), (3) duration of healing period before loading (conventional [T1] vs delayed [T2]), (4) region of implant placement (maxilla [M1] vs mandible [M2]), and (5) site of implant placement (anterior [A] vs posterior [P]). To find the significant difference between the bivariate samples in the independent groups, an unpaired sample t test was used. The average marginal bone loss during the healing phase was 0.56 ± 0.573 mm in the mesial region and 0.44 ± 0.549 mm in the distal region of the implant, with a statistically significant difference (P < .01). There was no statistically significant difference in crestal bone level with the (1) sex of the patient (male or female), (2) type of implant placement (I or D), (3) time of implant loading (T1 or T2), (4) region of implant placement (M1 or M2), or (5) site of implant in the arch (A or P) (P > .05). An average of 0.50 mm crestal bone loss occurred in the peri-implant region during the preprosthetic phase. We found that the delayed placement of an implant and a delay in the healing period would further increase the early implant bone loss. The difference in the healing period did not alter the outcome of the study.

Considering the Value of 3D Cultures for Enhancing the Understanding of Adhesion, Proliferation, and Osteogenesis on Titanium Dental Implants

BACKGROUND

Individuals with pathologic conditions and restorative deficiencies might benefit from a combinatorial approach encompassing stem cells and dental implants; however, due to the various surface textures and coatings, the influence of titanium dental implants on cells exhibits extensive, wide variations. Three-dimensional (3D) cultures of stem cells on whole dental implants are superior in testing implant properties and were used to examine their capabilities thoroughly.

MATERIALS AND METHODS

The surface micro-topography of five titanium dental implants manufactured by sandblasting with titanium, aluminum, corundum, or laser sintered and laser machined was compared in this study. After characterization, including particle size distribution and roughness, the adhesion, proliferation, and viability of adipose-derived stem cells (ADSCs) cultured on the whole-body implants were tested at three time points (one to seven days). Finally, the capacity of the implant to induce ADSCs' spontaneous osteoblastic differentiation was examined at the same time points, assessing the gene expression of collagen type 1 (coll-I), osteonectin (osn), alkaline phosphatase (alp), and osteocalcin (osc).

RESULTS

Laser-treated (Laser Mach and Laser Sint) implants exhibited the highest adhesion degree; however, limited proliferation was observed, except for Laser Sint implants, while viability differences were seen throughout the three time points, except for Ti Blast implants. Sandblasted surfaces (Al Blast, Cor Blast, and Ti Blast) outpaced the laser-treated ones, inducing higher amounts of coll-I, osn, and alp, but not osc. Among the sandblasted surfaces, Ti Blast showed moderate roughness and the highest superficial texture density, favoring the most significant spontaneous differentiation relative to all the other implant surfaces.

CONCLUSIONS

The results indicate that 3D cultures of stem cells on whole-body titanium dental implants is a practical and physiologically appropriate way to test the biological characteristics of the implants, revealing peculiar differences in ADSCs' adhesion, proliferation, and activity toward osteogenic commitment in the absence of specific osteoinductive cues. In addition, the 3D method would allow researchers to test various implant surfaces more thoroughly. Integrating with preconditioned stem cells would inspire a more substantial combinatorial approach to promote a quicker recovery for patients with restorative impairments.

Influence of buccal and palatal bone thickness on post-surgical marginal bone changes around implants placed in posterior maxilla: a multi-centre prospective study

BACKGROUND

Numerous clinical variables may influence early marginal bone loss (EMBL), including surgical, prosthetic and host-related factors. Among them, bone crest width plays a crucial role: an adequate peri-implant bone envelope has a protective effect against the influence of the aforementioned factors on marginal bone stability. The aim of the present study was to investigate the influence of buccal and palatal bone thickness at the time of implant placement on EMBL during the submerged healing period.

METHODS

Patients presenting a single edentulism in the upper premolar area and requiring implant-supported rehabilitation were enrolled following inclusion and exclusion criteria. Internal connection implants (Twinfit, Dentaurum, Ispringen, Germany) were inserted after piezoelectric implant site preparation. Mid-facial and mid-palatal thickness and height of the peri-implant bone were measured immediately after implant placement (T0) with a periodontal probe and recorded to the nearest 0.5 mm. After 3 months of submerged healing (T1), implants were uncovered and measurements were repeated with the same protocol. Kruskal-Wallis test for independent samples was used to compare bone changes from T0 to T1. Multivariate linear regression models were built to assess the influence of different variables on buccal and palatal EMBL.

RESULTS

Ninety patients (50 females, 40 males, mean age 42.9 ± 15.1 years), treated with the insertion of 90 implants in maxillary premolar area, were included in the final analysis. Mean buccal and palatal bone thickness at T0 were 2.42 ± 0.64 mm and 1.31 ± 0.38 mm, respectively. Mean buccal and palatal bone thickness at T1 were 1.92 ± 0.71 mm and 0.87 ± 0.49 mm, respectively. Changes in both buccal and palatal thickness from T0 to T1 resulted statistically significant (p = 0.000). Changes in vertical bone levels from T0 to T1 resulted not significant both on buccal (mean vertical resorption 0.04 ± 0.14 mm; p = 0.479) and palatal side (mean vertical resorption 0.03 ± 0.11 mm; p = 0.737). Multivariate linear regression analysis showed a significant negative correlation between vertical bone resorption and bone thickness at T0 on both buccal and palatal side.

CONCLUSION

The present findings suggest that a bone envelope > 2 mm on the buccal side and > 1 mm on the palatal side may effectively prevent peri-implant vertical bone resorption following surgical trauma.

TRIAL REGISTRATION

The present study was retrospectively recorded in a public register of clinical trials ( www.

CLINICALTRIALS

gov - NCT05632172) on 30/11/2022.

Oncostatin M regulates macrophages polarization in osseointegration via yes-associated protein

OBJECTIVES

Oncostatin M(OSM), secreted by monocytes and macrophages, has been noted to participate in bone homeostasis and macrophage polarization, which might be regulated by yes-associated protein (YAP). This study aimed to elucidate the influence and mechanisms of OSM-YAP on macrophages polarization in osseointegration.

MATERIAL AND METHODS

In vitro, flow cytometry, real-time PCR, and Elisa were performed to evaluate inflammatory function in bone marrow-derived macrophages (BMDMs) with OSM, siOSMR, and YAP inhibitor verteporfin (VP). In vivo, macrophage-specific YAP-deficient mice were generated to investigate the role of OSM via YAP signaling in osseointegration.

RESULTS

This study demonstrated that OSM could inhibit the M1 polarization, promote the M2 polarization, and induce the expression of osteogenic-related factors via VP. The conditional knock-out of YAP inhibited the osseointegration in mice, and promoted the inflammatory reaction around the implants, while OSM could restore the effect.

CONCLUSIONS

Our results demonstrated that OSM might play an important role in the polarization of BMDMs, and bone formation around dental and femoral implants. This effect was closely conducted by Hippo-YAP pathway.

CLINICAL SIGNIFICANCE

Understanding the role and mechanism of OSM in macrophage polarization around dental implants could improve comprehension of signal network of osseointegration, and it might offer a potential target of therapies to accelerate osseointegration and reduce inflammatory reactions.

Macrophage polarization in bone implant repair: A review

Macrophages (MΦ) are highly adaptable and functionally polarized cells that play a crucial role in various physiological and pathological processes. Typically, MΦ differentiate into two distinct subsets: the proinflammatory (M1) and anti-inflammatory (M2) phenotypes. Due to their potent immunomodulatory and anti-inflammatory properties, MΦ have garnered significant attention in recent decades. In the context of bone implant repair, the immunomodulatory function of MΦ is of paramount importance. Depending on their polarization phenotype, MΦ can exert varying effects on osteogenesis, angiogenesis, and the inflammatory response around the implant. This paper provides an overview of the immunomodulatory and inflammatory effects of MΦ polarization in the repair of bone implants.

Current Molecular, Cellular and Genetic Aspects of Peri-Implantitis Disease: A Narrative Review

(1) Background: Peri-implantitis is a multi-factorial disease with an inflammatory background that occurs in both soft and hard tissues surrounding implants. In recent years, the understanding of the cellular, molecular and genetic background of peri-implantitis has broadened. This study aims to summarize the currently available articles on the subject and highlight the most recent advances over the last 20 years. (2) Methods: For this study, the Embase and PubMed libraries were searched using the keywords: ("peri-implantitis" AND "cytokine" OR "genetics" OR "cellular") and ("peri-implantitis" AND "cytokine" OR "genetics" OR "cellular" AND "risk factors"). The search revealed a total of 3013 articles (992 from PubMed, 2021 from Embase). Following screening of the titles and abstracts and full-text reads, 55 articles were included. (3) Results: In peri-implantitis IL-6, IL-1β, TNF-α, MMP-8 and their genetic variations appear to be the most important cytokines in relation to not only pathogenesis, but also their potential diagnostic capabilities. Epithelial and inflammatory cells, along with those of the bone lineage, are prime cellular elements found in peri-implantitis. (4) Conclusions: A wide array of cells stand behind peri-implantitis, as well as cytokines and their genetic variations that take part in the process. However, the growing interest in this topic has led to the introduction of specific new diagnostic tools to enable a better understanding of patients' responses to treatment and, in turn, to even enable prediction of the risk of developing peri-implant disease.

Clinical and radiographic assessment of circular versus triangular cross-section neck implants in the posterior maxilla: Five-year follow-up of a randomized controlled trial

OBJECTIVES

Dental implants with a triangular neck design have been developed in order to maintain peri-implant bone. The primary aim of this randomized controlled trial (RCT) was to assess after 5 years the peri-implant bone stability and the peri-implant soft tissue conditions with this new triangular implant neck design compared to a conventional round neck implant design.

MATERIAL AND METHODS

This is a secondary evaluation of a RCT including 34 patients. Patients were recalled after 1, 3, and finally 5 years to assess implant survival and peri-implant bone levels using standardized radiographs. Peri-implant soft tissue health was also evaluated by recording probing depth, plaque index and Bleeding on Probing. Patient Reported Outcome Measures (PROMs) and the Pink Esthetic Score were also assessed.

RESULTS

No implant loss occurred during the 5-year follow up period. The mean ± SD proximal bone remodeling after 5 years reached 0.38 ± 0.39 mm for the circular design and 0.29 ± 0.58 mm for the triangular design (p = .49). Peri-implant soft tissue health parameters and PROMs were found to be comparable. Altogether, 80% of implants presented peri-implant mucositis whereas one implant (4%) displayed sings of peri-implantitis.

CONCLUSION

The 5-year evaluation of the triangular neck implants showed similar results to the circular neck implants.

The Effect of Hyperlipidemia on Peri-implant Health: A Clinical and Radiographical Prospective Study

High levels of cholesterol and triglycerides may have a negative effect on the immune system and bone health, leading to lower bone mineral density, an increased risk of osteoporosis, and bone fractures, and could therefore also be related to a significant worsening of peri-implant health. The purpose of the following study was to evaluate whether the altered lipid profile in patients who undergo implant insertion surgery represents a prognostic factor capable of influencing clinical outcomes. This prospective observational study was conducted on 93 subjects; patients were required to have taken blood tests to obtain triglycerides (TG), total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels prior to the surgical procedure to classify them according to current American Heart Association guidelines. The outcomes considered were marginal bone loss (MBL) 3 years after implant placement, full-mouth plaque score (FMPS), and full-mouth bleeding score (FMBS) 3 years after surgery. A statistically significant correlation was found between hypertriglyceridemia and MBL as well as between total cholesterol and MBL. There is no statistically significant correlation between the variables analyzed and the secondary outcomes 3 years after implant placement. Peri-implant marginal bone loss may be influenced by hyperlipidemia. However, further studies are needed, with larger samples and more extensive follow-ups, to confirm these results.

Ebselen restores peri-implantitis-induced osteogenic inhibition via suppressing BMSCs ferroptosis

It is hard to reconstruct bone defects in peri-implantitis due to osteogenesis inhibited by excessive ROS. Ferroptosis, a recently identified regulated cell death characterized by iron- and reactive oxygen species- (ROS-) dependent lipid peroxidation, provides us with a new explanation. Our study aims to explore whether ferroptosis is involved in peri-implantitis-inhibited osteogenesis and confirm ebselen, an antioxidant with glutathione peroxidase (GPx)-like activity, could inhibit ferroptosis and promote osteogenesis in peri-implantitis. In this study, we used LPS to mimic the microenvironment of peri-implantitis. The osteogenic differentiation of bone-marrow-derived mesenchymal stem cells (BMSCs) was assessed by alkaline phosphatase (ALP), Alizarin Red S, and mRNA and protein expression of osteogenic-related markers. Ferroptosis index analysis included iron metabolism, ROS production, lipid peroxidation and mitochondrial morphological changes. Iron overload, reduced antioxidant capability, excessive ROS, lipid peroxidation and the characteristic mitochondrial morphological changes of ferroptosis were observed in LPS-treated BMSCs, and adding Ferrostatin-1 (Fer-1) restored the inhibitory effect of ferroptosis on osteogenic differentiation of BMSCs. Furthermore, ebselen ameliorated LPS-induced ferroptosis and osteogenic inhibition, which was reversed by erastin. Our results demonstrated that ferroptosis is involved in osteogenic inhibition in peri-implantitis and ebselen could attenuate osteogenic dysfunction of BMSCs via inhibiting ferroptosis.

Effects of Hyperlipidemia on Osseointegration of Dental Implants and Its Strategies

Hyperlipidemia refers to the abnormal increase in plasma lipid level exceeding the normal range. At present, a large number of patients require dental implantation. However, hyperlipidemia affects bone metabolism, promotes bone loss, and inhibits the osseointegration of dental implants through the mutual regulation of adipocytes, osteoblasts, and osteoclasts. This review summarized the effects of hyperlipidemia on dental implants and addressed the potential strategies of dental implants to promote osseointegration in a hyperlipidemic environment and to improve the success rate of dental implants in patients with hyperlipidemia. We summarized topical drug delivery methods to solve the interference of hyperlipidemia in osseointegration, which were local drug injection, implant surface modification and bone-grafting material modification. Statins are the most effective drugs in the treatment of hyperlipidemia, and they also encourage bone formation. Statins have been used in these three methods and have been found to be positive in promoting osseointegration. Directly coating simvastatin on the rough surface of the implant can effectively promote osseointegration of the implant in a hyperlipidemic environment. However, the delivery method of this drug is not efficient. Recently, a variety of efficient methods of simvastatin delivery, such as hydrogels and nanoparticles, have been developed to boost bone formation, but few of them were applied to dental implants. Applicating these drug delivery systems using the three aforementioned ways, according to the mechanical and biological properties of materials, could be promising ways to promote osseointegration under hyperlipidemic conditions. However, more research is needed to confirm.

Interaction of Ceramic Implant Materials with Immune System

The immuno-compatibility of implant materials is a key issue for both initial and long-term implant integration. Ceramic implants have several advantages that make them highly promising for long-term medical solutions. These beneficial characteristics include such things as the material availability, possibility to manufacture various shapes and surface structures, osteo-inductivity and osteo-conductivity, low level of corrosion and general biocompatibility. The immuno-compatibility of an implant essentially depends on the interaction with local resident immune cells and, first of all, macrophages. However, in the case of ceramics, these interactions are insufficiently understood and require intensive experimental examinations. Our review summarizes the state of the art in variants of ceramic implants: mechanical properties, different chemical modifications of the basic material, surface structures and modifications, implant shapes and porosity. We collected the available information about the interaction of ceramics with the immune system and highlighted the studies that reported ceramic-specific local or systemic effects on the immune system. We disclosed the gaps in knowledge and outlined the perspectives for the identification to ceramic-specific interactions with the immune system using advanced quantitative technologies. We discussed the approaches for ceramic implant modification and pointed out the need for data integration using mathematic modelling of the multiple ceramic implant characteristics and their contribution for long-term implant bio- and immuno-compatibility.

Bridging the Gap with Nanoparticles: A Novel Approach

Two-piece implants unavoidably present a microgap between the implant and the abutment interface. Although numerous modalities have been attempted to overcome this situation, the implant abutment interface still remains a critical point for microbial colonization, which starts an inflammatory cascade of events eventually compromising the implants. Throughout our life, cells in all biological systems are unprotected to oxidative stress leading to the formation of Reactive oxygen species which is of concern when it comes to placing implants in patients who are periodontally compromised. This necessitates the development of alternative therapeutic modalities, which could counteract as well as prevent the microbial overload and ROS generation thereby improving the longevity of implants. To evaluate and assess the antibacterial, antioxidant and anti inflammatory effectiveness of quercetin-loaded titanium nanocomposites as coatings over healing abutments. Quercetin-loaded titanium nanocomposites were synthesized using green synthesis and confirmation was done using UV spectroscopy. Healing abutments were coated with the formulated nanocomposites, an intra-oral environment was simulated by thermocycling. Their antibacterial, antioxidant, anti-inflammatory, and cytotoxicity were assessed using standard tests. Healing abutments were coated with the formulated nanocomposites, an intra-oral environment was simulated by thermocycling. They showed potent antibacterial, antioxidant, and anti-inflammatory properties, which could prove beneficial in a variety of clinical scenarios in which there is a high risk for implant failure during early osseointegration.

Marginal bone changes around platform-switched conical connection implants placed 1 or 2 mm subcrestally: A multicenter crossover randomized controlled trial

INTRODUCTION

This study analyzes early marginal bone modifications occurring around platform-switched implants with conical connection placed 1 or 2 mm subcrestally.

METHODS

This crossover randomized controlled trial enrolled partially edentulous patients needing two implants in either the posterior maxilla or mandible. Each patient received two platform-switched implants with conical connection inserted 2 mm (Test) and 1 mm (Control) subcrestally. Definitive abutments were immediately connected and, after 4 months of unsubmerged healing, screwed metal-ceramic crowns were delivered. Radiographs were taken at implant placement (T0), prosthesis delivery (T1), and after 1 year of prosthetic loading (T2).

RESULTS

Fifty-one patients (25 males and 26 females; mean age 61.2 ± 12.1 years) totaling 102 implants were included in the final analysis. Mean peri-implant bone level (PBL) reduction from T0 to T2 was not significantly different around Test (0.49 ± 0.32 mm) and Control implants (0.46 ± 0.35 mm; p = 0.66). Multivariate linear regression models highlighted a significant positive correlation between history of periodontitis and PBL reduction. At T2, no Test group implant and 6 Control group implants exhibited PBL below the implant platform (11.8% of Control group implants).

CONCLUSION

No significant differences in peri-implant marginal bone changes were demonstrated after 1 year of prosthetic loading between platform-switched implants with conical connection inserted either 1 or 2 mm subcrestally. However, 2 mm subcrestal placement resulted in deeper implant positioning at T2, with no exposure of treated implant surface and potential preventive effect against subsequent peri-implant pathology.

Photobiomodulation in dental implant stability and post-surgical healing and inflammation. A randomised double-blind study

BACKGROUND

The aim of this randomized clinical trial was to evaluate the effect of diode laser photobiomodulation (PBM) on post-surgical healing, inflammation and implant stability.

METHODS

Forty dental implants were inserted into 13 patients. The implants were randomly divided into two groups. The test group (PBM+) underwent two sessions of PBM (combined diode laser of 630 and 808 nm), the first of which after surgery, and the second, 7 days after the surgical procedure. The control group (PBM-) received simulated laser treatment. The implant stability quotient (ISQ) was determined immediately after the surgical procedure, and 7 days, 4 and 8 weeks later. Post-surgical inflammation was assessed following the criteria described by Bloemen and Cols. Healing was calculated using the healing index (HI).

RESULTS

No differences were found in terms of the mean values of implant stability between the test and control groups over time. Only two of the implants (18.2%) from the PBM- group were classified with the maximum healing index (HI = 5), whereas in the PBM+ group, nine implants (45%) were classified with the aforementioned index (P < 0.0001). Using the logistic regression, it was determined that the non-application of the laser in the PBM- group caused an OR of 4.333 times of presenting inflammation (IC95% 1.150-16.323; P = 0.030).

CONCLUSIONS

The application of 808 nm infra-red laser for bone tissue, and 630 nm for mucosal tissue in two sessions is considered to be an effective way of reducing inflammation and improving early healing. More studies are needed to confirm these results.

Clinical effects of conventional and underprepared drilling preparation of the implant site based on bone density: A systematic review and meta-regression

PURPOSE

There is no clinical consensus to determine the right balance between underpreparation and marginal bone level changes. The purpose of this systematic review and meta-regression was to investigate the influence of the type of drilling preparation of the implant site in relation to the bone mineral density on the clinical success, expressed in terms of the MBL and implant failure rate.

STUDY SELECTION

A thorough search was performed using the digital databases MEDLINE PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used were "dental implants", "bone density", and "torque".

RESULTS

The mean bone resorption in the conventional preparation group was -0.43 (± 0.28) mm, whereas it was -0.80 (± 0.37) mm in the underprepared group. For the D1/D2/D3 bone group, the slope was significantly different from zero and linearity; the D4 bone group slope was not significantly different from zero and was almost parallel, although it was significantly different from linearity. The box and whiskers plot shows that the MBL in underprepared sites tended to be significantly higher with a higher variation than that in conventionally prepared sites.

CONCLUSIONS

Within its limits, our meta-regression analysis showed that MBL is influenced by the type of drilling preparation and bone mineral density. In particular, a lower MBL was observed in the D1 bone with conventional preparation than with underpreparation. Moreover, a greater implant-to-osteotomy site mismatch was positively associated with greater MBLs in the bone densities of D1/D2/D3.

High-fat diet causes undesirable bone regeneration by altering the bone marrow environment in rats

OBJECTIVE

Diet structure has changed greatly over the last few decades, and high-calorie diets have become an integral part of people's daily diet, as well as the important cause of obesity in society. Several organ systems, including the skeletal system, are seriously affected by high-fat-diets (HFD) in the world. There is, however, still a lack of knowledge about the effects of HFD on bone regeneration and the possible mechanisms involved. In this study, the difference in bone regeneration between rats under HFD and low-fat-diets (LFD) was evaluated by monitoring the process of bone regeneration in distraction osteogenesis (DO) model animals, as well as the possible mechanisms.

METHODS

A total of 40 Sprague Dawley (SD) rats (5 weeks old) were randomly divided into HFD group (n=20) and LFD group (n=20). Except for feeding methods, there were no differences between the two groups in terms of treatment conditions. All animals received the DO surgery eight weeks after starting to feed. After a delay of 5 days (latency phase), the active lengthening phase was performed for 10 days (0.25 mm/12 h), and the consolidation phase followed for 42 days. An observational study of bone included radioscopy (once a week), micro-computed tomography (CT), general morphology, biomechanics, histomorphometry, and immunohistochemistry.

RESULT

The results showed that HFD group had a higher body weight than LFD group after 8, 14, and 16 weeks of feeding. Furthermore, at the final observation, there were statistically significant differences between LFD group and HFD group in terms of total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels. Additionally, observations on bone regeneration showed a slower regeneration and a lower biomechanical strength in HFD group than LFD group, based on radiography, micro-CT, general morphology, biomechanics, histomorphometry, and immunohistochemistry.

CONCLUSION

In this study, HFD resulted in elevated blood lipids, increased adipose differentiation at the bone marrow level, and delayed bone regeneration. The pieces of evidence are beneficial to better understand the association between diet and bone regeneration and to adjust the diet optimally for fracture patients.

Topography-mediated immunomodulation in osseointegration; Ally or Enemy

Osteoimmunology is at full display during endosseous implant osseointegration. Bone formation, maintenance and resorption at the implant surface is a result of bidirectional and dynamic reciprocal communication between the bone and immune cells that extends beyond the well-defined osteoblast-osteoclast signaling. Implant surface topography informs adherent progenitor and immune cell function and their cross-talk to modulate the process of bone accrual. Integrating titanium surface engineering with the principles of immunology is utilized to harness the power of immune system to improve osseointegration in healthy and diseased microenvironments. This review summarizes current information regarding immune cell-titanium implant surface interactions and places these events in the context of surface-mediated immunomodulation and bone regeneration. A mechanistic approach is directed in demonstrating the central role of osteoimmunology in the process of osseointegration and exploring how regulation of immune cell function at the implant-bone interface may be used in future control of clinical therapies. The process of peri-implant bone loss is also informed by immunomodulation at the implant surface. How surface topography is exploited to prevent osteoclastogenesis is considered herein with respect to peri-implant inflammation, osteoclastic precursor-surface interactions, and the upstream/downstream effects of surface topography on immune and progenitor cell function.

The Construction and Evaluation of a Multi-Task Convolutional Neural Network for a Cone-Beam Computed-Tomography-Based Assessment of Implant Stability

Objectives: Assessing implant stability is integral to dental implant therapy. This study aimed to construct a multi-task cascade convolution neural network to evaluate implant stability using cone-beam computed tomography (CBCT). Methods: A dataset of 779 implant coronal section images was obtained from CBCT scans, and matching clinical information was used for the training and test datasets. We developed a multi-task cascade network based on CBCT to assess implant stability. We used the MobilenetV2-DeeplabV3+ semantic segmentation network, combined with an image processing algorithm in conjunction with prior knowledge, to generate the volume of interest (VOI) that was eventually used for the ResNet-50 classification of implant stability. The performance of the multitask cascade network was evaluated in a test set by comparing the implant stability quotient (ISQ), measured using an Osstell device. Results: The cascade network established in this study showed good prediction performance for implant stability classification. The binary, ternary, and quaternary ISQ classification test set accuracies were 96.13%, 95.33%, and 92.90%, with mean precisions of 96.20%, 95.33%, and 93.71%, respectively. In addition, this cascade network evaluated each implant's stability in only 3.76 s, indicating high efficiency. Conclusions: To our knowledge, this is the first study to present a CBCT-based deep learning approach CBCT to assess implant stability. The multi-task cascade network accomplishes a series of tasks related to implant denture segmentation, VOI extraction, and implant stability classification, and has good concordance with the ISQ.

Is medication related osteonecrosis of the jaw around implants a rare entity? A case series with a focus on etiopathophysiology

OBJECTIVES

Medication Related Osteonecrosis of the Jaw (MRONJ) around dental implants is a rare complication of antiresorptive drug (ARD) treatment. MRONJ has been described in patients with implants placed before, during or after ARD treatment. The aim of this study was to review our cases and to discuss a preventive approach to avoid the risk of MRONJ around implants.

MATERIALS AND METHODS

In a retrospective analysis of the 168 MRONJ seen in our department from 2005 to 2021, we searched for cases of patients with MRONJ around dental implants.

RESULTS

Six patients (4 females, 2 males) presented with MRONJ around 17 implants. Median age was 64 (50-83) years. Four patients received ARD treatment for osteoporosis and 2 for cancer. The maxilla was more affected than the mandible. Six implants were placed after the initiation of ARD treatment and eleven were placed before initiation of ARD treatments. Eight implants were managed surgically while 9 implants were managed conservatively.

CONCLUSION

In this series, implants were placed before or after starting ARD treatment. Despite initial successful osseointegration, MRONJ occurred months or years after initiation of ARD treatment. The role of periimplantitis should be discussed as well as the role of microcracks in the bone following implant loading. Less is known over the effect of ARD treatment after implant osseointegration. Implants could be a risk factor for MRONJ and must be checked regularly (every 3 months). It is important to check the healthy and biomechanical harmony of the implant system during the pre-treatment assessment.

Recovering Osteoblast Functionality on TiO2 Nanotube Surfaces Under Diabetic Conditions

Introduction

Titanium (Ti) and its alloys (eg, Ti₆Al₄V) are exceptional treatments for replacing or repairing bones and damaged surrounding tissues. Although Ti-based implants exhibit excellent osteoconductive performance under healthy conditions, the effectiveness and successful clinical achievements are negatively altered in diabetic patients. Concernedly, diabetes mellitus (DM) contributes to osteoblastic dysfunctionality, altering efficient osseointegration. This work investigates the beneficial osteogenic activity conducted by nanostructured TiO₂ under detrimental microenvironment conditions, simulated by human diabetic serum.

Methods

We evaluated the bone-forming functional properties of osteoblasts on synthesized TiO₂ nanotubes (NTs) by anodization and Ti6Al4V non-modified alloy surfaces under detrimental diabetic conditions. To simulate the detrimental environment, MC3T3E-1 preosteoblasts were cultured under human diabetic serum (DS) of two diagnosed and metabolically controlled patients. Normal human serum (HS) was used to mimic health conditions and fetal bovine serum (FBS) as the control culture environment. We characterized the matrix mineralization under the detrimental conditions on the control alloy and the NTs. Moreover, we applied immunofluorescence of osteoblasts differentiation markers on the NTs to understand the bone-expression stimulated by the biochemical medium conditions.

Results

The diabetic conditions depressed the initial osteoblast growth ability, as evidenced by altered early cell adhesion and reduced proliferation. Nonetheless, after three days, the diabetic damage was suppressed by the NTs, enhancing the osteoblast activity. Therefore, the osteogenic markers of bone formation and the differentiation of osteoblasts were reactivated by the nanoconfigured surfaces. Far more importantly, collagen secretion and bone-matrix mineralization were stimulated and conducted to levels similar to those of the control of FBS conditions, in comparison to the control alloy, which was not able to reach similar levels of bone functionality than the NTs.

Conclusion

Our study brings knowledge for the potential application of nanostructured biomaterials to work as an integrative platform under the detrimental metabolic status present in diabetic conditions.

Assessing the Efficacy of Whole-Body Titanium Dental Implant Surface Modifications in Inducing Adhesion, Proliferation, and Osteogenesis in Human Adipose Tissue Stem Cells

BACKGROUND

Although the influence of titanium implants' micro-surface properties on titanium discs has been extensively investigated, the research has not taken into consideration their whole-body effect, which may be considered possible using a combinatorial approach.

METHODS

Five titanium dental implants with a similar moderate roughness and different surface textures were thoroughly characterized. The cell adhesion and proliferation were assessed after adipose-tissue-derived stem cells (ADSCs) were seeded on whole-body implants. The implants' inductive properties were assessed by evaluating the osteoblastic gene expression.

RESULTS

The surface micro-topography was analyzed, showing that hydroxyapatite (HA)-blasted and bland acid etching implants had the highest roughness and a lower number of surface particles. Cell adhesion was observed after 24 h on all the implants, with the highest score registered for the HA-blasted and bland acid etching implants. Cell proliferation was observed only on the laser-treated and double-acid-etched surfaces. The ADSCs expressed collagen type I, osteonectin, and alkaline phosphatase on all the implant surfaces, with high levels on the HA-treated surfaces, which also triggered osteocalcin expression on day seven.

CONCLUSIONS

The findings of this study show that the morphology and treatment of whole titanium dental implants, primarily HA-treated and bland acid etching implants, impact the adherence and activity of ADSCs in osteogenic differentiation in the absence of specific osteo-inductive signals.