Research on implants and osseointegration

Preparation and Biological Evaluation of Porous Tantalum Scaffolds Coated with Hydroxyapatite

Orthopedic implants, such as porous scaffolds, are an effective way to repair bone defects. However, the lack of osseointegration and osteoinduction limits the achievement of an ideal therapeutic effect. This study aimed to prepare hydroxyapatite (HA) coatings for the surface of porous tantalum (Ta) scaffolds and to assess the effectively improved biological activities of the coated scaffolds. The porous Ta scaffolds were prepared by chemical vapor deposition, and then the porous Ta scaffolds were coated with HA via electrochemical deposition. The elements and phase compositions of the coatings were analyzed by energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that the coating covered the whole surfaces of porous Ta scaffolds with a uniform and compact distribution and did not exert any obvious effect on the porous structure. The biological activity of porous Ta scaffolds after surface modification increased and the water contact angle decreased, indicating that hydrophilicity was significantly improved. Cell live/dead staining, cytoskeletal fluorescence staining, and alkaline phosphatase immunofluorescence staining showed that the coating exhibited no cytotoxicity and notably improved cell proliferation, spreading, and osteogenic differentiation. In addition, in vivo experiments in animals have demonstrated that HA-coated porous Ta scaffolds contribute to bone formation. In conclusion, the HA coating notably improves the biological activities of the porous Ta scaffolds, achieving the goal of the present study. The HA coating presents great potential for the modification of porous Ta implants to improve their osteogenesis and osseointegration.

Osseointegration potential of boron-coated titanium alloy pedicle screw in rabbit spine model

BACKGROUND

Spinal implants' longevity is crucial, but titanium alloys, while advantageous, lack strong bone integration. This study aimed to achieve better osseointegration rates by utilizing the ability of boron compounds to transform stem cells in the vertebra into osteoblasts.

METHOD

Twenty male albino rabbits were divided into control (n = 10) and experimental (n = 10) groups. Control group received titanium alloy pedicle screws, while experimental group received boron-coated titanium alloy screws. Under general anesthesia, screws were inserted into the L6 and L7 lumbar spines. After 16 weeks, all animals were euthanized for histological examination. Vertebra samples underwent decalcification and H&E staining. Microscopic examination assessed osseointegration, necrosis, fibrosis, and vascularization using a triple scoring system by two blinded observers.

RESULT

In the boron-coated titanium alloy group, all subjects exhibited osseointegration, with 50% showing focal, 40% moderate, and 10% complete osseointegration. In the titanium alloy group, 90% showed osseointegration (70% focal, 10% moderate, and 10% complete).The differences between the groups were not statistically significant (p = 0.302). Focal necrosis rates were similar between groups, with 50.0% in the titanium alloy and 60.0% in the boron-coated group (p = 0.653).Fibrosis was absent in the titanium alloy group but present in the boron-coated group, albeit with lower rates of focal fibrosis (20.0%). However, the difference was not statistically significant (p = 0.086).Vascularization patterns showed no significant difference between groups.

CONCLUSION

Boron-coated titanium alloy pedicle screws provided osseointegration rates comparable to standard titanium screws and exhibited acceptable levels of necrosis and fibrosis. With stronger biomechanical properties, they could be a better alternative to currently used titanium screws.

The influence of two distinct surface modification techniques on the clinical efficacy of titanium implants: A systematic review and meta-analysis

PURPOSE

To compare the effectiveness of anodized and sandblasted large-grit acid-etched surface modification implants in clinical applications.

METHODS

This systematic review has been registered at PROSPERO (CRD42023423656). A systematic search was performed using seven databases. The meta-analysis was performed using the RevMan 5.4 program and Stata 17.0 software. An analysis of the risk of bias in the included studies was conducted using the Cochrane Handbook for Systematic Reviews of Interventions and the Newcastle-Ottawa scale.

RESULTS

A comprehensive analysis of 16 studies, which collectively encompassed a total of 2768 implants, was finished. Following a five years follow-up, the meta-analysis showed that the cumulative survival rate of implants was lower in the anodized group compared to the sandblasted large-grit acid-etched group (RR, 3.47; 95 % confidence interval [CI], 1.23 to 9.81; P = 0.02). Furthermore, the anodized group and the sandblasted large-grit acid-etched group had similar marginal bone loss over the one to three years follow-up period. However, it was observed that the marginal bone loss increased at the five years follow-up period in the anodized group in comparison to the sandblasted large-grit acid-etched group (SMD, 2.98; 95 % CI, 0.91 to 5.06; P = 0.005). In terms of biological complications, plaque index, bleeding on probing, and probing pocket depth, we found no statistically significant differences between the anodized and sandblasted large-grit acid-etched group.

CONCLUSIONS

The sandblasted large-grit acid-etched group exhibited higher implants cumulative survival rate and less marginal bone loss compared to the anodized group. Moreover, both groups demonstrated similar incidences of biological complications, plaque index, bleeding on probing, and probing pocket depth, suggesting overall equivalence in these aspects.

Investigation of the extent of post-extraction bone contraction and remodeling after 4 months. A prospective pilot study

OBJECTIVES

To investigate the correlation between the serum levels of 25(OH)D and the resorption of the alveolar bone walls and regeneration of the alveolar space after tooth extraction.

METHODS

14 adults in need of extraction of hopeless teeth were enrolled. An intraoral digital impression was performed, and each patient was tested to assess serum vitamin D levels. Subsequently, extraction of teeth and contextual guided bone regeneration was performed using porcine origin graft material and a resorbable collagen membrane to covert the defect. After 4 months, an impression was taken, and the model was scanned using a professional scanner for lab. At the same time, a cone beam computed tomography was performed to plan implant insertion through fully digital computer guided surgery. Bone was collected to perform histological and histomorphometric analysis. Pre and postoperative scans were compared using a specific software to estimate the volumetric changes. Tests were applied to investigate the relationship between the different predictor variables and the outcome variables.

RESULTS

14 patients were divided in 3 groups depending on the serum Vit-D levels, identifying three ranges corresponding to low (lower than 20), medium (between 20 and 30), and optimal vitamin D levels (higher than 30). Volumetric contraction after extraction was observed for all patients, without any significant difference between the groups. Focusing on the post-extraction regeneration, patients belonging to the group with lower levels of Vit-D displayed lower and more disorganized levels of bone. Immunohistochemistry analysis showed that Col1A1 and Osteocalcin had no physiological alteration. Osteopontin could be identified near the external surface of bone tissue granules. Runx2 signals were detected near the margins of bone trabeculae.

CONCLUSIONS

Serum vit-D levels do not appear to influence the extent of post-extraction bone contraction; on the contrary, they seem to influence the post-extraction regeneration.

CLINICAL SIGNIFICANCE

Vit D serum levels may influence the regenerative aspect during post-extraction turn-over. This might suggest controlling and (in case of low levels) recommend Vit D supplement in the patient diet in case of extraction.

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.

Percutaneous removal of hardware after orthopedic surgery: Is it safe? and What are patients saying?

OBJECTIVES

To analyze our patient's complication profile and rate after removal of hardware (ROH) surgery, and survey our patients to ask their overall status and improvement in symptomatology post-operatively.

DESIGN

Retrospective chart review and survey.

SETTING

Academic, tertiary referral center.

PATIENTS/PARTICIPANTS

173 patients with 314 pieces of hardware. Seventy-six patients (43.9%) responded to our survey.

INTERVENTION

ROH surgery.

MAIN OUTCOME MEASUREMENTS

Patient demographics and complications were recorded. All patients were sent a brief 3-question survey which asked: (1) Why did you get your hardware removed? (2) How did your overall status change after ROH? (3) How did the ROH affect your stiffness, pain, swelling, and mobility?

RESULTS

There were 10 complications (5.5%): 5 infections, 2 with unresolved pain, 1 hematoma, 1 chronic regional pain syndrome exacerbation, and 1 recurrent deformity. All infections were treated with oral antibiotics and improved. All other complications resolved with treatment except for the patient who developed recurrent deformity. Patients underwent ROH surgery because their doctor suggested it (76.3%) and to improve mobility (39.5%). 86.9% reported their overall status improved after ROH. They improved regarding stiffness (73.7%), pain (73.6%), swelling (61.8%), and mobility (76.3%). Similar results were seen among different implants removed.

CONCLUSIONS

The majority of patients who underwent percutaneous ROH were satisfied. They reported improvement in stiffness, pain, swelling and mobility (greatest improvement). The complication rate was low (5.5%). ROH can be a meaningful operation to patients allowing them to improve their quality of life with a low complication rate.

LEVEL OF EVIDENCE

Level IV.

Effect of angled abutments in the posterior maxillary region on tilted implants: a 3D finite element analysis

The aim of this study was to evaluate the bone tissue effects under dynamic loading using finite element analysis (FEA) for four angled abutments with different deviated palatal lateral tilt angles. A three-dimensional model of the posterior maxillary region and an implant crown model were reconstructed and assembled with a three-dimensional model of the implant, angled abutment, and central screw to create a total of 10 three-dimensional finite element models tilted at 15 ∘ , 20 ∘ , 25 ∘ , and 30 ∘ in three groups, and the dynamic loads simulating oral mastication were loaded on the implant crown to analyze the equivalent stresses and strains in the peri-implant bone tissues. Under the dynamic loading, the cortical bone on the buccal side of the implant neck showed different degrees of stress concentration, and the cortical bone stress was much higher than the cancellous bone, and the strain concentration area of each model was located in the bone tissue around the implant neck and base. For the use of angular abutment, under the premise that the cortical bone stresses and strains of the 10 models meet the requirements for use, the peak stresses of 2.907 MPa, 3.018 MPa, and 2.164 MPa were achieved by using the 20 ∘ angular abutment to achieve the tilt angles of 20 ∘ , 25 ∘ , and 30 ∘ implantation, which is more advantageous compared with other models.

Biomimetic Porous Ti6Al4V Implants: A Novel Interbody Fusion Cage via Gel-Casting Technique to Promote Spine Fusion

An interbody fusion cage (Cage) is crucial in spinal decompression and fusion procedures for restoring normal vertebral curvature and rebuilding spinal stability. Currently, these Cages suffer from issues related to mismatched elastic modulus and insufficient bone integration capability. Therefore, a gel-casting technique is utilized to fabricate a biomimetic porous titanium alloy material from Ti6Al4V powder. The biomimetic porous Ti6Al4V is compared with polyetheretherketone (PEEK) and 3D-printed Ti6Al4V materials and their respective Cages. Systematic validation is performed through mechanical testing, in vitro cell, in vivo rabbit bone defect implantation, and ovine anterior cervical discectomy and fusion experiments to evaluate the mechanical and biological performance of the materials. Although all three materials demonstrate good biocompatibility and osseointegration properties, the biomimetic porous Ti6Al4V, with its excellent mechanical properties and a structure closely resembling bone trabecular tissue, exhibited superior bone ingrowth and osseointegration performance. Compared to the PEEK and 3D-printed Ti6Al4V Cages, the biomimetic porous Ti6Al4V Cage outperforms in terms of intervertebral fusion performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. This biomimetic porous Ti6Al4V Cage offers cost-effectiveness, presenting significant potential for clinical applications in spinal surgery.

The role of N-acetylcysteine in osteogenic microenvironment for bone tissue engineering

Bone defect is a common clinical symptom which can arise from various causes. Currently, bone tissue engineering has demonstrated positive therapeutic effects for bone defect repair by using seeding cells such as mesenchymal stem cells and precursor cells. N-acetylcysteine (NAC) is a stable, safe and highly bioavailable antioxidant that shows promising prospects in bone tissue engineering due to the ability to attenuate oxidative stress and enhance the osteogenic potential and immune regulatory function of cells. This review systematically introduces the antioxidant mechanism of NAC, analyzes the advancements in NAC-related research involving mesenchymal stem cells, precursor cells, innate immune cells and animal models, discusses its function using the classic oral microenvironment as an example, and places particular emphasis on the innovative applications of NAC-modified tissue engineering biomaterials. Finally, current limitations and future prospects are proposed, with the aim of providing inspiration for targeted readers in the field.

Effect of anti-resorptive therapy on implant failure: a systematic review and meta-analysis

PURPOSE

This review was conducted to systematically assess the impact of bisphosphonates (BPs) and denosumab, used as anti-resorptive therapies, on the incidence of dental implant failure.

METHODS

Electronic and manual searches were performed in accordance with the described search protocol. Only articles that met the inclusion criteria were selected. The primary outcome was implant failure, while secondary outcomes included biological complications and comorbidities. Following data extraction, a quality assessment and meta-analysis were conducted.

RESULTS

Fourteen eligible studies were included in the analysis following a qualitative evaluation. BP administration, regardless of the timing of anti-resorptive therapy, did not significantly increase the risk of implant failure (odds ratio [OR], 1.40; 95% confidence interval, 0.83-2.34). Subgroup analysis revealed a slightly higher, although statistically insignificant, risk of failure in patients with a follow-up period of 3 years or more compared to those with a follow-up duration of less than 3 years (with ORs of 2.82 and 1.53, respectively). Due to a lack of eligible studies, a meta-analysis for denosumab could not be conducted.

CONCLUSIONS

Our findings suggest that BP treatment does not compromise the survival of dental implants. Specifically, in patients with osteoporosis, implant failure rates were not significantly influenced by the administration of BPs before the placement of dental implants, suggesting that low-dose BP therapy may not contraindicate implant placement. Nevertheless, regular check-ups and maintenance periodontal treatment must not be neglected, and concomitant biological factors should be considered to ensure the long-term success of implant rehabilitation.

Advances in biomaterials for oral-maxillofacial bone regeneration: spotlight on periodontal and alveolar bone strategies

The intricate nature of oral-maxillofacial structure and function, coupled with the dynamic oral bacterial environment, presents formidable obstacles in addressing the repair and regeneration of oral-maxillofacial bone defects. Numerous characteristics should be noticed in oral-maxillofacial bone repair, such as irregular morphology of bone defects, homeostasis between hosts and microorganisms in the oral cavity and complex periodontal structures that facilitate epithelial ingrowth. Therefore, oral-maxillofacial bone repair necessitates restoration materials that adhere to stringent and specific demands. This review starts with exploring these particular requirements by introducing the particular characteristics of oral-maxillofacial bones and then summarizes the classifications of current bone repair materials in respect of composition and structure. Additionally, we discuss the modifications in current bone repair materials including improving mechanical properties, optimizing surface topography and pore structure and adding bioactive components such as elements, compounds, cells and their derivatives. Ultimately, we organize a range of potential optimization strategies and future perspectives for enhancing oral-maxillofacial bone repair materials, including physical environment manipulation, oral microbial homeostasis modulation, osteo-immune regulation, smart stimuli-responsive strategies and multifaceted approach for poly-pathic treatment, in the hope of providing some insights for researchers in this field. In summary, this review analyzes the complex demands of oral-maxillofacial bone repair, especially for periodontal and alveolar bone, concludes multifaceted strategies for corresponding biomaterials and aims to inspire future research in the pursuit of more effective treatment outcomes.

Chronic exposure to TiO2 micro- and nano particles: A biochemical and histopathological experimental study

The aim of this work was to analyze the effects of long-term exposure to titanium dioxide (TiO2) micro- (MPs) and nanoparticles (NPs) (six and 12 months) on the biochemical and histopathological response of target organs using a murine model. Male Wistar rats were intraperitoneally injected with a suspension of TiO2 NPs (5 nm; TiO2-NP5 group) or MPs (45 μm; TiO2-NP5 group); the control group was injected with saline solution. Six and 12 months post-injection, titanium (Ti) concentration in plasma and target organs was determined spectrometrically (ICP-MS). Blood smears and organ tissue samples were evaluated by light microscopy. Liver and kidney function was evaluated using serum biochemical parameters. Oxidative metabolism was assessed 6 months post-injection (determination of superoxide anion by nitroblue tetrazolium (NBT) test, superoxide dismutase (SOD) and catalase (CAT), lipid peroxidation, and paraoxonase 1). Titanium (Ti) concentration in target organs and plasma was significantly higher in the TiO2-exposed groups than in the control group. Histological evaluation showed the presence of titanium-based particles in the target organs, which displayed no structural alterations, and in blood monocytes. Oxidative metabolism analysis showed that TiO2 NPs were more reactive over time than MPs (p < .05) and mobilization of antioxidant enzymes and membrane damage varied among the studied organs. Clearance of TiO2 micro and nanoparticles differed among the target organs, and lung clearance was more rapid than clearance from the lungs and kidneys (p < .05). Conversely, Ti concentration in plasma increased with time (p < .05). In conclusion, neither serum biochemical parameters nor oxidative metabolism markers appear to be useful as biomarkers of tissue damage in response to TiO2 micro- and nanoparticle deposits at chronic time points.

Surface topography modulates initial platelet adhesion to titanium substrata

The clinical success of implanted biomaterials such as dental implants is largely determined by the molecular signaling that occurs at the tissue-implant interface. The modification of surface topography is a widely-employed strategy for optimizing tissue integration with dental implants. However, little is known regarding the direct, cellular-level effects of substratum topography on platelet signaling and adhesion, despite these cells being the first to encounter the implant surface during surgical placement. Here we compared platelet adhesion and secretion on four (4) different titanium surfaces, notably, the modifications applied to commercially available dental implants: smooth (S) titanium; acid-etched (AE), sandblasted (SB) and a combined acid-etching/sandblasting procedure (SLA). Platelets were isolated from human blood, washed, and seeded on to the 4 test surfaces; platelet adhesion was quantified by microscopy. In addition, the secretion of critical molecules stored in platelet granules (platelet factor 4, PF4; soluble P-selectin, sCD62P; transforming growth factor-beta1, TGF-β1; platelet-derived growth factor-AB, PDGF-AB) was measured by enzyme-linked immunosorbent assay (ELISA) analysis of the supernatants. There was greater platelet adhesion to the rougher AE and SB surfaces, however, the concentration of the secreted growth factors was comparable on all surfaces. We conclude that while surface topography can be engineered to modulate initial platelet adhesion, granule secretion is likely regulated as a separate and independent process.

Effects of nanomodified titanium surfaces considering bacterial colonization and viability of osteoblasts and fibroblasts

This study investigates nanostructured titanium surfaces (Ti2 spikes) that promote the viability of osteoblasts and fibroblasts and prevent bacterial colonisation. Helium ion irradiation was adopted to produce nanometric-sized cones on titanium. Human osteoblasts (hFOB) and human gingiva fibroblasts (hGF) were used for analysis. A viability and a cytotoxicity assay were conducted to evaluate the lactate dehydrogenase (LDH) activity and assess cell damage in Ti2 spikes compared to titanium discs with a sandblasted and acid-etched (Ti2 SLA) surface. The antibacterial activity was investigated against Escherichia coli, Streptococcus mutans, Fusobacterium nucleatum, and Porphyromonas gingivalis. In the course of the cultivation, both hGF and hFOB demonstrated significantly reduced viability on the Ti2 spikes surface. hGF cells exhibited a slight but significant increase in LDH release. In contrast, hFOB showed reduced cytotoxicity on this surface. On the Ti2 spikes surface, hGF cells exhibited a significant reduction in gene expression of VCL, Src-1, and ITGα5. However, the integrin subunits ITGα1 and ITGα3 showed upregulation on the Ti2 spikes surface. The Ti2 spikes surface significantly increased the expression of almost all osteogenic markers. The results of conventional culturing demonstrated a statistically significant decrease in the number of viable cells for S. mutans, F. nucleaum, and greater quantities of P. gingivalis on Ti2 spikes surface compared to control. However, no such reduction was detected for E. coli. The long-term success of implants relies on establishing and maintaining hard and soft peri-implant tissues. Ti2 spikes represent a novel and promising approach to enhance osseointegration and optimize biocompatibility.

Peri-implant epidermoid cyst: A case report and literature analysis

BACKGROUND

A peri-implant cystic lesion is a rare finding, and to date most investigators have considered that its pathogenesis is caused by trauma and infection related to dental implantation. However, the pathogenesis of these cysts remains unclear and is recognized to have multifactorial origins.

CASE PRESENTATION

In February 2021, a 75-year-old male patient underwent implant restoration due to mobility of the left maxillary central incisor. The implant achieved good osseointegration and was successfully restored. However, in March 2023, the patient sought treatment due to mobility of the dental implant. Clinical examination showed that the implant had loosened in three directions (vertical, mesial-distal, and labial-lingual), and the peri-implant mucosa was slightly red and swollen. Radiographic examination (cone beam computed tomography) showed a large radiolucent area with clear boundaries involving the cervical and middle portions of the dental implant, and white bone lines were observed at the edge of the low-density shadow. Intraoperatively, we removed the patient's implant, performed a complete debridement, and conducted bone augmentation surgery in the area of bone defect. Postoperatively, the patient recovered well. The final histopathological result confirmed an epidermoid cyst.

CONCLUSIONS

Peri-implant epidermoid cyst is a rare complication that affects the long-term outcome of implant therapy. This case serves as a warning to clinicians to avoid involving epithelial tissue in the implant site during implant surgery, in order to prevent the potential occurrence of a peri-implant epidermoid cyst, thereby creating better conditions for the patient's recovery and the long-term efficacy of the implant.

Nanoscale osseointegration of zirconia evaluated from the interfacial structure between ceria-stabilized tetragonal zirconia and cell-induced hydroxyapatite

BACKGROUND

The osseointegration of zirconia implants has been evaluated based on their implant fixture bonding with the alveolar bone at the optical microscopic level. Achieving nano-level bonding between zirconia and bone apatite is crucial for superior osseointegration; however, only a few studies have investigated nanoscale bonding. This review outlines zirconia osseointegration, including surface modification, and presents an evaluation of nanoscale zirconia-apatite bonding and its structure.

HIGHLIGHT

Assuming osseointegration, the cells produced calcium salts on a ceria-stabilized zirconia substrate. We analyzed the interface between calcium salts and zirconia substrates using transmission electron microscopy and found that 1) the cell-induced calcium salts were bone-like apatite and 2) direct nanoscale bonding was observed between the bone-like apatite and zirconia crystals without any special modifications of the zirconia surface.

CONCLUSION

Structural affinity exists between bone apatite and zirconia crystals. Apatite formation can be induced by the zirconia surface. Zirconia bonds directly with apatite, indicating superior osseointegration in vivo.

Allylamine coating on zirconia dental implant surface promotes osteogenic differentiation in vitro and accelerates osseointegration in vivo

OBJECTIVES

The glow discharge plasma (GDP) procedure has proven efficacy in grafting allylamine onto zirconia dental implant surfaces to enhance osseointegration. This study explored the enhancement of zirconia dental implant properties using GDP at different energy settings (25, 50, 75, 100, and 200 W) both in vitro and in vivo.

MATERIALS AND METHODS

In vitro analyses included scanning electron microscopy, wettability assessment, energy-dispersive X-ray spectroscopy, and more. In vivo experiments involved implanting zirconia dental implants into rabbit femurs and later evaluation through impact stability test, micro-CT, and histomorphometric measurements.

RESULTS

The results demonstrated that 25 and 50 W GDP allylamine grafting positively impacted MG-63 cell proliferation and increased alkaline phosphatase activity. Gene expression analysis revealed upregulation of OCN, OPG, and COL-I. Both 25 and 50 W GDP allylamine grafting significantly improved zirconia's surface properties (p < .05, p < .01, p < .001). However, only 25 W allylamine grafting with optimal energy settings promoted in vivo osseointegration and new bone formation while preventing bone level loss around the dental implant (p < .05, p < .01, p < .001).

CONCLUSIONS

This study presents a promising method for enhancing Zr dental implant surface's bioactivity.

Occlusal force orchestrates alveolar bone homeostasis via Piezo1 in female mice

Healthy alveolar bone is the cornerstone of oral function and oral treatment. Alveolar bone is highly dynamic during the entire lifespan and is affected by both systemic and local factors. Importantly, alveolar bone is subjected to unique occlusal force in daily life, and mechanical force is a powerful trigger of bone remodeling, but the effect of occlusal force in maintaining alveolar bone mass remains ambiguous. In this study, the Piezo1 channel is identified as an occlusal force sensor. Activation of Piezo1 rescues alveolar bone loss caused by a loss of occlusal force. Moreover, we identify Piezo1 as the mediator of occlusal force in osteoblasts, maintaining alveolar bone homeostasis by directly promoting osteogenesis and by sequentially regulating catabolic metabolism through Fas ligand (FasL)-induced osteoclastic apoptosis. Interestingly, Piezo1 activation also exhibits remarkable efficacy in the treatment of alveolar bone osteoporosis caused by estrogen deficiency, which is highly prevalent among middle-aged and elderly women. Promisingly, Piezo1 may serve not only as a treatment target for occlusal force loss-induced alveolar bone loss but also as a potential target for metabolic bone loss, especially in older patients.

Identifying an optimal approach for the placement of pterygoid implants: A 3D finite element analysis

STATEMENT OF PROBLEM

A consensus on the optimal approach to the placement of pterygoid implants is lacking.

PURPOSE

The purpose of this finite element analysis study was to determine the optimal approach to the placement of pterygoid implants by comparing biomechanical behavior.

MATERIAL AND METHODS

An edentulous and moderately atrophic maxilla with the anatomic structure of the pterygomaxillary region was constructed. Complete arch restorations with 4 standard anterior implants and pterygoid implants in 3 approaches were simulated: L70, long pterygoid implants (4.1×18 mm) inclined at 70 degrees relative to the Frankfort horizontal plane with anchorage in the pterygoid process; L45, long pterygoid implants (4.1×20 mm) inclined at 45 degrees with anchorage in the pterygoid process; and S45, shorter pterygoid implants (4.1×13 mm) inclined 45 degrees without apical anchorage. The L70, L45, and S45 groups were classified as D or S depending on the bone quality: D3 (dense trabecular bone) or D4 (sparse trabecular bone). A total of 6 finite element models were built. The bone failure theory, based on the von Mises theory, was used to judge yielding of the trabecular bone. The von Mises stress (σVM) distribution was measured in the cortical bone, the trabecular bone, and on the implant surface. Deformation (DF) distribution was obtained for the entire bone (DFB) and bone surrounding the pterygoid implant (DFP).

RESULTS

L70 showed a lower maximum σVM value (maxσVM), more uniform σVM distribution in the cortical bone, trabecular bone, and on the implant surface and a lower maximum DFp value (maxDFp), especially in the D4 bone. The biomechanical behaviors were similar in L45 and S45 with no stress distribution in the pterygoid process. In the D4 bone, L70, L45, and S45 exceeded the limited stress of the bone failure theory by 50%, 130%, and 130%, while all values were under the limit in D3 bone.

CONCLUSIONS

The approach of pterygoid implants inclined at 70 degrees relative to the Frankfort plane with anchorage in the pterygoid process was optimal, providing improved biomechanical behavior. Clinically, in the case of D4 bone, the inclined angulation of pterygoid implants should be 70 degrees to minimize the risk of failure.

Chitosan nanoparticle applications in dentistry: a sustainable biopolymer

The epoch of Nano-biomaterials and their application in the field of medicine and dentistry has been long-lived. The application of nanotechnology is extensively used in diagnosis and treatment aspects of oral diseases. The nanomaterials and its structures are being widely involved in the production of medicines and drugs used for the treatment of oral diseases like periodontitis, oral carcinoma, etc. and helps in maintaining the longevity of oral health. Chitosan is a naturally occurring biopolymer derived from chitin which is seen commonly in arthropods. Chitosan nanoparticles are the latest in the trend of nanoparticles used in dentistry and are becoming the most wanted biopolymer for use toward therapeutic interventions. Literature search has also shown that chitosan nanoparticles have anti-tumor effects. This review highlights the various aspects of chitosan nanoparticles and their implications in dentistry.

Ion-incorporated titanium implants for staged regulation of antibacterial activity and immunoregulation-mediated osteogenesis

Antibacterial properties and osteogenic activity are considered as two crucial factors for the initial healing and long-term survivability of orthopedic implants. For decades, various drug-loaded implants to enhance biological activities have been investigated extensively. More importantly, to control the drug release timing is equally significant due to the sequential biological processes after implantation. Hence, developing a staged regulation system on the titanium surface is practically significant. Here, we prepared TiO2 nanotubes (TiO2 NTs) on the titanium surface by anodization, followed by the incorporation of zinc (Zn) and strontium (Sr) sequentially through a hydrothermal process. Surface characterization confirmed the successful fabrication of Zn and Sr-incorporated TiO2 NTs (Zn-Sr/TiO2) on the titanium surface. The ion release results exhibited the differential release characteristic of Zn and Sr, which meant the early-stage release of Zn and the long-term release of Sr. It was exactly in accord with  the biological process after implantation, laying the basis of staged regulation after implantation. Zn-Sr/TiO2 showed favorable anti-early infection properties both in vitro and in vivo. Its inhibition effect on bacterial biofilm formation was attributed to the resistance against bacteria's initial adhesion and the killing effect on planktonic bacteria. Additionally, the release of Sr could alleviate infection-induced damage via immunoregulation. The biocompatibility and osteogenic activity mediated by M2 macrophage activation were confirmed with in vitro and in vivo studies. Therefore, it exhibited great potential in staged regulation for antibacterial activity in the early stage and the M2 activation-mediated osteogenic activity in the late stage. The staged regulation process was based on the differential release of Zn and Sr to achieve the early antibacterial effect and the long-term immune-induced osteogenic activity, to prevent implant-related infection and achieve better osseointegration. These two kinds of ions played their roles synergistically and complement mutually. This work is expected to provide an innovative idea for realizing sequential regulation after implantation.

Comparison of Zirconia Implant Surface Modifications for Optimal Osseointegration

Zirconia ceramic implants are commercially available from a rapidly growing number of manufacturers. Macroscopic and microscopic surface design and characteristics are considered to be key determining factors in the success of the osseointegration process. It is, therefore, crucial to assess which surface modification promotes the most favorable biological response. The purpose of this study was to conduct a comparison of modern surface modifications that are featured in the most common commercially available zirconia ceramic implant systems. A review of the currently available literature on zirconia implant surface topography and the associated bio-physical factors was conducted, with a focus on the osseointegration of zirconia surfaces. After a review of the selected articles for this study, commercially available zirconia implant surfaces were all modified using subtractive protocols. Commercially available ceramic implant surfaces were modified or enhanced using sandblasting, acid etching, laser etching, or combinations of the aforementioned. From our literature review, laser-modified surfaces emerged as the ones with the highest surface roughness and bone-implant contact (BIC). It was also found that surface roughness could be controlled to achieve optimal roughness by modifying the laser output power during manufacturing. Furthermore, laser surface modification induced a very low amount of preload microcracks in the zirconia. Osteopontin (OPN), an early-late osteogenic differentiation marker, was significantly upregulated in laser-treated surfaces. Moreover, surface wettability was highest in laser-treated surfaces, indicating favorable hydrophilicity and thus promoting early bone forming, cell adhesion, and subsequent maturation. Sandblasting followed by laser modification and sandblasting followed by acid etching and post-milling heat treatment (SE-H) surfaces featured comparable results, with favorable biological responses around zirconia implants.

Exploring the Impact of Copper Oxide Substitution on Structure, Morphology, Bioactivity, and Electrical Properties of 45S5 Bioglass®

In recent decades, the requirements for implantable medical devices have increased, but the risks of implant rejection still exist. These issues are primarily associated with poor osseointegration, leading to biofilm formation on the implant surface. This study focuses on addressing these issues by developing a biomaterial for implant coatings. 45S5 bioglass® has been widely used in tissue engineering due to its ability to form a hydroxyapatite layer, ensuring a strong bond between the hard tissue and the bioglass. In this context, 45S5 bioglasses®, modified by the incorporation of different amounts of copper oxide, from 0 to 8 mol%, were synthesized by the melt-quenching technique. The incorporation of Cu ions did not show a significant change in the glass structure. Since the bioglass exhibited the capacity for being polarized, thereby promoting the osseointegration effectiveness, the electrical properties of the prepared samples were studied using the impedance spectroscopy method, in the frequency range of 102-106 Hz and temperature range of 200-400 K. The effects of CuO on charge transport mobility were investigated. Additionally, the bioactivity of the modified bioglasses was evaluated through immersion tests in simulated body fluid. The results revealed the initiation of a Ca-P-rich layer formation on the surface within 24 h, indicating the potential of the bioglasses to enhance the bone regeneration process.

Mettl3‑mediated m6A RNA methylation regulates osteolysis induced by titanium particles

Peri‑prosthetic osteolysis (PPO) induced by wear particles is considered the primary cause of titanium prosthesis failure and revision surgery. The specific molecular mechanisms involve titanium particles inducing multiple intracellular pathways, which impact disease prevention and the targeted therapy of PPO. Notably, N6‑methyladenosine (m6A) serves critical roles in epigenetic regulation, particularly in bone metabolism and inflammatory responses. Thus, the present study aimed to determine the role of RNA methylation in titanium particle‑induced osteolysis. Results of reverse transcription‑quantitative PCR (RT‑qPCR), western blotting, ELISA and RNA dot blot assays revealed that titanium particles induced osteogenic inhibition and proinflammatory responses, accompanied by the reduced expression of methyltransferase‑like (Mettl) 3, a key component of m6A methyltransferase. Specific lentiviruses vectors were employed for Mettl3 knockdown and overexpression experiments. RT‑qPCR, western blotting and ELISA revealed that the knockdown of Mettl3 induced osteogenic inhibition and proinflammatory responses comparable with that induced by titanium particle, while Mettl3 overexpression attenuated titanium particle‑induced cellular reactions. Methylated RNA immunoprecipitation‑qPCR results revealed that titanium particles mediated the methylation of two inhibitory molecules, namely Smad7 and SMAD specific E3 ubiquitin protein ligase 1, via Mettl3 in bone morphogenetic protein signaling, leading to osteogenic inhibition. Furthermore, titanium particles induced activation of the nucleotide binding oligomerization domain 1 signaling pathway through methylation regulation, and the subsequent activation of the MAPK and NF‑κB pathways. Collectively, the results of the present study indicated that titanium particles utilized Mettl3 as an upstream regulatory molecule to induce osteogenic inhibition and inflammatory responses. Thus, the present study may provide novel insights into potential therapeutic targets for aseptic loosening in titanium prostheses.

Involvement of interlukin-17A (IL-17A) gene polymorphism and interlukin-23 (IL-23) level in the development of peri-implantitis

BACKGROUND

Dental implantation has been practiced since ancient times and has gone through several stages. Dentists use dental implants to support dental prostheses such as crowns, bridges, dentures, face prostheses, or as an orthodontic anchor. Thus, the purpose of this study is to detect the role of the immune-genetic variation of IL-17A and related inflammatory cytokine (IL-23) in the initiation and progress of peri implantitis.

MATERIAL AND METHODS

This cross-sectional study included 80 subjects (15 peri-implantitis patients, 35 successful implants, and 30 healthy controls); their mean age was (43.91 ± 11.33) years. Blood samples and Peri-implant sulcus fluid (PISF) were collected from all subjects (patients with peri-implantitis, successful implants, and healthy controls) attending the Department of Oral and Maxillofacial Surgery in the Dental College Teaching Hospital, Baghdad University, Baghdad, Iraq. The blood sample detects gene polymorphisms in interleukin-17A by a polymerase chain reaction (PCR). An enzyme-linked immunosorbent assay (ELISA) was carried out to estimate the Peri-implant sulcus fluid (PISF) levels of interleukin-23.

RESULT

The current study revealed an obvious significant elevation in the mean level of interleukin-23 in the peri-implantitis patient's group more than its level in the successful implant and control groups (P < 0.05). In addition, the result showed that A/A genotype is associated significantly with peri-implantitis OR (95%confidence interval) =6.9 (1.7121 to 27.4638) folds increase risk of peri-implantitis) (p = 0.0065), while G/A genotype had OR 4.9 (0.9539-24.9394) folds increased risk of peri-implantitis, (p = 0.0572). But it was not statistically significant and G/G genotype had a one-fold increase risk of peri-implantitis.

CONCLUSION

The increased level of inflammatory cytokine (interleukin-23) might add to the systemic inflammatory burden a predisposing factor, which may lead to impaired osseointegration and subsequent bone loss or implant failure. In addition, IL-17A gene polymorphism may play a role in peri-implant disease susceptibility, especially in persons carrying the rs2275913 A allele at a higher risk of developing peri-implantitits as compared with those carrying the G allele.

Infrared diode laser enhances human periodontal ligament stem cells behaviour on titanium dental implants

Low level laser treatment (LLLT) is known for its photobiostimulatory and photobiomodulatory characteristics, which stimulate cell proliferation, increase cellular metabolism, and improve cellular regeneration. The objective of the present research was to assess the possible influence of infrared diode laser irradiation on the behaviour, attachment, and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) seeded on different types of dental implants. Two distinct types of implants, one subjected to laser surface treatment and the other treated with acid etching, were longitudinally divided into two halves and submerged in six wells culture plates. Both implants were subjected to infrared diode laser treatment, and subsequently, the morphology and attachment of cells were examined using scanning electron microscopy (SEM) after 14 and 21 days. The behaviour of (hPDLSCs) towards two types of implants, when exposed to osteogenic medium and low-level laser therapy (LLLT), was assessed using quantitative real-time polymerase chain reaction to measure the expression of stemness markers and osteogenic markers. The scanning electron microscopy (SEM) demonstrated that the application of infrared diode laser irradiation substantially improved the attachment of cells to both types of implants. The stemness gene markers were significantly down regulated in cells seeded on both surfaces when challenged with osteogenic media in relation to control. At 14 days, early osteogenic markers, were upregulated, while late osteogenic markers, were downregulated in both challenged groups. At the 21-day mark, hPDLSCs seeded on an acid-etched implant exhibited increased expression of all osteogenic markers in response to stimulation with osteogenic media and infra-red diode laser, in contrast to hPDLSCs seeded on a laser surface treated implant under the same conditions. Finally, the findings of our research revealed that when subjected to infrared diode laser, human periodontal ligament stem cells cultured on both types of implants demonstrated improved cellular attachment and differentiation. This suggested that infrared diode laser enhanced the activity of the cells surrounding the implants. Hence, the use of infrared diode laser could be pivotal in improving and expediting the clinical osseointegration process around dental implants.

Breakthroughs in Oral and Maxillofacial Surgery

In the field of oral and maxillofacial surgery, continuous advances have ushered in a new era of innovation, profoundly influencing this branch of medicine [...].

Influence of the Addition of Zinc, Strontium, or Magnesium Oxides to the Bioglass 45S5 Network on Electrical Behavior

45S5 Bioglass has been widely used in regenerative medicine due to its ability to dissolve when inserted into the body. Its typically amorphous structure allows for an ideal dissolution rate for the formation of the hydroxyapatite layer, which is important for the development of new bone. This bioactive capacity can also be controlled by adding other oxides (e.g., SrO, ZnO, and MgO) to the 45S5 Bioglass network or by storing electrical charge. Ions such as zinc, magnesium, and strontium allow for specific biological responses to be added, such as antibacterial action and the ability to increase the rate of osteoblast proliferation. The charge storage capacity allows for a higher rate of bioactivity to be achieved, allowing for faster attachment to the host bone, decreasing the patient's recovery time. Therefore, it is necessary to understand the variation in the structure of the bioglass with regard to the amount of non-bridging oxygens (NBOs), which is important for the bioactivity rate not to be compromised, and also its influence on the electrical behavior relevant to its potential as electrical charge storage. Thus, several bioactive glass compositions were synthesized based on the 45S5 Bioglass formulation with the addition of various concentrations (0.25, 0.5, 1, and 2, mol%) of zinc, strontium, or magnesium oxides. The influence of the insertion of these oxides on the network was evaluated by studying the amount of NBOs using Raman spectroscopy and their implication on the electrical behavior. Electrical characterization was performed in ac (alternating current) and dc (direct current) regimes.

Comparative Evaluation of C-Reactive Protein Levels among Peri-Implant Health and Disease Conditions

Peri-implant disease pathogenesis results in production of pro-inflammatory mediators, among which C-reactive protein (CRP) is one of the acute phase reactants. The aim of the study was to comparative CRP levels among peri-implant health and disease conditions. The present study was carried out in the Department of Implantology, Saveetha Dental College and Hospitals, Chennai, India. A total of 40 patients with peri-implant health (n = 10), peri-mucositis (n = 10), early peri-implantitis (n = 10) and advanced peri-implantitis (n = 10) were enrolled. Unstimulated salivary samples were collected and subjected to latex agglutination assay for CRP analysis. CRP levels were then correlated with peri-implant health and diseases. CRP level in peri-implant health, peri-implant mucositis, early peri-implantitis and advanced peri-implantitis were 0.18 ± 0.04 mg/dL, 2.05 ± 0.61 mg/dL, 4.14 ± 1.82 mg/dL and 6.21 ± 1.35 mg/dL respectively. There was a statistically significant difference in CRP levels between all the tested groups (ANOVA, P = 0.03). Pearson correlation coefficient analysis revealed a strong positive correlation between CRP and peri-implant health status. CRP level was high among patients with peri-implantitis followed by peri-implant mucositis and peri-implant health. Also, CRP level increases with severity of peri-implant diseases and there exists a positive correlation between CRP level and peri-implant health status.

Recombinant human secretory leukocyte protease inhibitor (rhSLPI) coated titanium enhanced human osteoblast adhesion and differentiation

Osseointegration is vital to success in orthopedic and dental reconstructions with implanted materials. The bone matrix or cells-particularly osteoblasts-are required to achieve functional contact on the implant surface. Osteoblast induction is therefore essential for osteogenesis to occur. Enhancement of osteoblast adhesion, proliferation, and differentiation, particularly by implant surface modifications, have been found challenging to develop. Secretory Leukocyte Protease Inhibitor (SLPI), a cation ionic protein with anti-inflammatory and anti-bacterial activities, showed activation in osteoblast proliferation and differentiation. However, the effects of coating recombinant human (rh) SLPI on a titanium alloy surface on human osteoblast adhesion, proliferation, and differentiation has never been investigated. In this study, titanium alloys (Ti-6Al-4V) were coated with rhSLPI, while human osteoblast adhesion, proliferation, differentiation, actin cytoskeletal organization, and gene expressions involved in cell adhesion and differentiation were investigated. The results indicate that coating titanium with 10-100 µg/ml rhSLPI enhanced the physical properties of the Ti surface and enhanced human osteoblast (hFOB 1.19) cell adhesion, activated actin dynamic, enhanced adhesive forces, upregulated integrins α1, α2, and α5, enhanced cell proliferation, mineralization, alkaline phosphatase activity, and upregulated ALP, OCN, and Runx2. This is the first study to demonstrate that coating SLPI on titanium surfaces enhances osseointegration and could be a candidate molecule for surface modification in medical implants.

Trichostatin A enhances the titanium rods osseointegration in osteoporotic rats by the inhibition of oxidative stress through activating the AKT/Nrf2 pathway

The use of titanium implants as fixed supports following fractures in patients with OP can often result in sterile loosening and poor osseointegration. Oxidative stress has been shown to play a particularly important role in this process. While TSA has been reported to facilitate in vivo osteogenesis, the underlying mechanisms remain to be clarified. It also remains unclear whether TSA can improve the osseointegration of titanium implants. This study investigated whether TSA could enhance the osseointegration of titanium rods by activating AKT/Nrf2 pathway signaling, thereby suppressing oxidative stress. MC3T3-E1 cells treated with CCCP to induce oxidative stress served as an in vitro model, while an OVX-induced OP rat model was employed for in vivo analysis of titanium rod implantation. In vitro, TSA treatment of CCCP-treated MC3T3-E1 cells resulted in the upregulation of osteogenic proteins together with increased AKT, total Nrf2, nuclear Nrf2, HO-1, and NQO1 expression, enhanced mitochondrial functionality, and decreased oxidative damage. Notably, the PI3K/AKT inhibitor LY294002 reversed these effects. In vivo, TSA effectively enhanced the microstructural characteristics of distal femur trabecular bone, increased BMSCs mineralization capacity, promoted bone formation, and improved the binding of titanium implants to the surrounding tissue. Finally, our results showed that TSA could reverse oxidative stress-induced cell damage while promoting bone healing and improving titanium rods' osseointegration through AKT/Nrf2 pathway activation.

Finite element analysis of the angle range in trans-inferior alveolar nerve implantation at the mandibular second molar

BACKGROUND

Trans- inferior alveolar nerve (IAN) implantation technique was wildly used while the potential appropriate angle range in which the residual alveolar bone can bear the stress without absorption are currently unclear. This study aimed to evaluate the stress distribution pattern of the interface between bone and implant by finite element analysis (FEA) to determine the appropriate range of the implant tilt angle.

METHODS

Cone beam computed tomography (CBCT) images of 120 patients with missing mandibular second molars and vertical bone height < 9 mm in the edentulous area were selected. The distances from the mandibular nerve canal to the buccal cortex, the lingual cortex and the alveolar ridge crest were measured by using a combination of software. The angular ranges of the buccal-lingual inclination of simulated trans-IAN implants were measured and three-dimensional finite element models were constructed in the mandibular second molar area according to the differences of the inclination angles. A vertical load (200N) was then applied to analyze the biomechanical conditions of the implant-bone interface during median occlusion.

RESULTS

The distance at the second molar from the nerve canal to the buccal cortex, lingual cortex and alveolar crest were 6.861 ± 1.194 mm, 2.843 ± 0.933 mm and 7.944 ± 0.77 mm. Trans-IAN implantation was feasible in 73.33% of patients. The minimum angle and maximum angles of the buccal-lingual inclination of the simulated implant were 19.135 ± 6.721° and 39.282 ± 6.581°. When a vertical static load of 200N was applied, the tensile stress in cortical bone gradually increased with the increase of the implant tilt angle. When the inclination angle reached 30°, the tensile stress (105.9 MPa) exceeded the yield strength (104 MPa) of cortical bone. Compared with the conventional implants, the stress peak value of the vertical ultra-short implant in cortical bone was greater than the stress peak value of the conventional implants at 10°(79.81 MPa) and 20°(82.83 MPa) and was smaller than the stress of the implant at 30°(105.9 MPa) and 40°(107.8 MPa). Therefore, when the bone mass allows, conventional-length implants should be selected whenever possible, and an operative range of the trans-IAN implantation in the mandibular second molar could be retained with an inclination angle of < 30°.

CONCLUSIONS

The mandibular nerve canal at the mandibular second molar was obviously biased to the lingual side, which ensured sufficient bone mass at the buccal side. In most patients with severe mandibular atrophy, it was possible to maintain a safe distance from the nerve canal with conventional-length implants via the trans-IAN implantation technique.

Influence of Topography and Composition of Commercial Titanium Dental Implants on Cell Adhesion of Human Gingiva-Derived Mesenchymal Stem Cells: An In Vitro Study

The topography and composition of dental implant surfaces directly impact mesenchymal cell adhesion, proliferation, and differentiation, crucial aspects of achieving osseointegration. However, cell adhesion to biomaterials is considered a key step that drives cell proliferation and differentiation. The aim of this study was to characterize characterize the topography and composition of commercial titanium dental implants manufactured with different surface treatments (two sandblasted/acid-etched (SLA) (INNO Implants, Busan, Republic of Korea; BioHorizonsTM, Oceanside, CA, USA) and two calcium phosphate (CaP) treated (Biounite®, Berazategui, Argentina; Zimmer Biomet, Inc., Warsaw, IN, USA)) and to investigate their influence on the process of cell adhesion in vitro. A smooth surface implant (Zimmer Biomet, Inc.) was used as a control. For that, high-resolution methodologies such as scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDX), laser scanning confocal microscopy (LSCM), and atomic force microscopy (AFM) were employed. Protein adsorption and retromolar gingival mesenchymal stem cells (GMSCs) adhesion to the implant surfaces were evaluated after 48 h. The adherent cells were examined by SEM and LSCM for morphologic and quantitative analyses. ANOVA and Tukey tests (α = 0.05) were employed to determine statistical significance. SEM revealed that INNO, BioHorizonsTM, and Zimmer implants have an irregular surface, whereas Biounite® has a regular topography consisting of an ordered pattern. EDX confirmed a calcium and phosphate layer on the Biounite® and Zimmer surfaces, and AFM exhibited different roughness parameters. Protein adsorption and cell adhesion were detected on all the implant surfaces studied. However, the Biounite® implant with CaP and regular topography showed the highest protein adsorption capacity and density of adherent GMSCs. Although the Zimmer implant also had a CaP treatment, protein and cell adhesion levels were lower than those observed with Biounite®. Our findings indicated that the surface regularity of the implants is a more determinant factor in the cell adhesion process than the CaP treatment. A regular, nanostructured, hydrophilic, and moderately rough topography generates a higher protein adsorption capacity and thus promotes more efficient cell adhesion.

Construction of functional surfaces for dental implants to enhance osseointegration

Dental implants have been extensively used in patients with defects or loss of dentition. However, the loss or failure of dental implants is still a critical problem in clinic. Therefore, many methods have been designed to enhance the osseointegration between the implants and native bone. Herein, the challenge and healing process of dental implant operation will be briefly introduced. Then, various surface modification methods and emerging biomaterials used to tune the properties of dental implants will be summarized comprehensively.

Guided immediate implant with and without using a mixture of autogenous and xeno bone grafts in the dental esthetic zone. A randomized clinical trial

PURPOSE

This in vivo study aims to assess the pink esthetic score in the anterior maxilla after computer-guided immediate implant installation and fully digital immediate temporalization with and without grafting the jumping gap with a mixture of 1:1 autogenous and xenograft particulates.

MATERIALS AND METHODS

Twenty-four patients with non-restorable upper anterior teeth in the aesthetic zone have undergone a traumatic extraction for the non-restorable tooth followed by immediate implant placement using a 3D-printed surgical guide according to prosthetically driven implant placement. The patients were divided into two groups. The study group received the dental implant after grafting the jumping gap with 1:1 autogenous and xenograft particulates, while the control group received the dental implant without grafting the jumping gap. Each patient received a digitally fabricated, immediate, nonfunctional temporary prosthesis. The esthetic outcome was compared between the two groups using the pink esthetic score at implant insertion and after 6 months of follow-up. Statistical comparisons were carried out between the studied groups using the Mann-Whitney U test.

RESULTS

Immediately postoperatively, there was no statistically significant difference between the median PES in the two groups (P-value = 0.746). After six months, the study group showed a statistically significantly higher median PES than the control group (P-value = 0.048).

CONCLUSIONS

Grafting the jumping distance in the immediate implant protocol helps achieve a better esthetic outcome.

CLINICAL RELEVANCE

The use of immediate guided implant placement along with grafting the jumping gap followed by immediate digital temporalization guarantees a better esthetic outcome while preserving time, cost, and the number of clinical visits.

TRIAL REGISTRATION

The study was registered on clinicaltrials.gov with registration number NCT04096209. (19/9/2019).

Magnesium-based alloys with adapted interfaces for bone implants and tissue engineering

Magnesium and its alloys are one of the most used materials for bone implants and tissue engineering. They are characterized by numerous advantages such as biodegradability, high biocompatibility and mechanical properties with values close to the human bone. Unfortunately, the implant surface must be adequately tuned, or Mg-based alloys must be alloyed with other chemical elements due to their increased corrosion effect in physiological media. This article reviews the clinical challenges related to bone repair and regeneration, classifying bone defects and presenting some of the most used and modern therapies for bone injuries, such as Ilizarov or Masquelet techniques or stem cell treatments. The implant interface challenges are related to new bone formation and fracture healing, implant degradation and hydrogen release. A detailed analysis of mechanical properties during implant degradation is extensively described based on different literature studies that included in vitro and in vivo tests correlated with material properties' characterization. Mg-based trauma implants such as plates and screws, intramedullary nails, Herbert screws, spine cages, rings for joint treatment and regenerative scaffolds are presented, taking into consideration their manufacturing technology, the implant geometrical dimensions and shape, the type of in vivo or in vitro studies and fracture localization. Modern technologies that modify or adapt the Mg-based implant interfaces are described by presenting the main surface microstructural modifications, physical deposition and chemical conversion coatings. The last part of the article provides some recommendations from a translational perspective, identifies the challenges associated with Mg-based implants and presents some future opportunities. This review outlines the available literature on trauma and regenerative bone implants and describes the main techniques used to control the alloy corrosion rate and the cellular environment of the implant.

In vitro fatigue behavior and in vivo osseointegration of the auxetic porous bone screw

The incidence of screw loosening, migration, and pullout caused by the insufficient screw-bone fixation stability is relatively high in clinical practice. To solve this issue, the auxetic unit-based porous bone screw (AS) has been put forward in our previous work. Its favorable auxetic effect can improve the primary screw-bone fixation stability after implantation. However, porous structure affected the fatigue behavior and in vivo longevity of bone screw. In this study, in vitro fatigue behaviors and in vivo osseointegration performance of the re-entrant unit-based titanium auxetic bone screw were studied. The tensile-tensile fatigue behaviors of AS and nonauxetic bone screw (NS) with the same porosity (51%) were compared via fatigue experiments, fracture analysis, and numerical simulation. The in vivo osseointegration of AS and NS were compared via animal experiment and biomechanical analysis. Additionally, the effects of in vivo dynamic tensile loading on the osseointegration of AS and NS were investigated and analyzed. The fatigue strength of AS was approximately 43% lower while its osseointegration performance was better than NS. Under in vivo dynamic tensile loading, the osseointegration of AS and NS both improved significantly, with the maximum increase of approximately 15%. Preferrable osseointegration of AS might compensate for the shortage of fatigue resistance, ensuring its long-term stability in vivo. Adequate auxetic effect and long-term stability of the AS was supposed to provide enough screw-bone fixation stability to overcome the shortages of the solid bone screw, developing the success of surgery and showing significant clinical application prospects in orthopedic surgery. STATEMENT OF SIGNIFICANCE: This research investigated the high-cycle fatigue behavior of re-entrant unit-based auxetic bone screw under tensile-tensile cyclic loading and its osseointegration performance, which has not been focused on in existing studies. The fatigue strength of auxetic bone screw was lower while the osseointegration was better than non-auxetic bone screw, especially under in vivo tensile loading. Favorable osseointegration of auxetic bone screw might compensate for the shortage of fatigue resistance, ensuring its long-term stability and longevity in vivo. This suggested that with adequate auxetic effect and long-term stability, the auxetic bone screw had significant application prospects in orthopedic surgery. Findings of this study will provide a theoretical guidance for design optimization and clinical application of the auxetic bone screw.

In Vitro Characterization of an Anodized Surface of a Dental Implant Collar and Dental Abutment on Peri-Implant Cellular Response

The purpose of this paper was to determine the effect of anodization on the in vitro proliferation and adhesion of immortalized human keratinocytes (HaCats) and mouse bone marrow-derived mesenchymal stem cells (BM-MSCs) in Titanium Grade 23 (Ti6Al4V ELI) discs and to describe the surface topography, roughness, and composition of dental implants (body and collar) and abutments submitted to an area-specific anodization process. HaCat cells and BM-MSCs were seeded onto discs with three different surface treatments: machined, area-specific anodization for abutments, and area-specific anodization for implant collars. Cell proliferation was assessed using a resazurin-based fluorescent dye on days 1, 3, and 7, while cell adhesion was examined using scanning electron microscopy (SEM). Surface topography, roughness, and composition were evaluated for six implant bodies with an anodized rough surface, six anodized implant smooth collars, and six anodized prosthetic abutments. Both HaCats and BM-MSCs showed increased viability over time (p < 0.001) with no statistically significant differences among the different surfaces (p = 0.447 HaCats and p = 0.631 BM-MSCs). SEM analysis revealed an enhanced presence and adhesion of HaCat cells on the anodized surface for the implant collars and an increased adhesion of BM-MSCs on both the anodized and machined surface abutments. The topography characteristics of the treated implants and abutments varied depending on the specific implant region. Chemical analysis confirmed the presence of oxygen, calcium, phosphorus, and sodium on the anodized surfaces. The area-specific anodization process can be utilized to create variable topography, increase the specific surface area, and introduce oxygen, calcium, phosphorus, and sodium to dental implants and abutments. While BM-MSCs and HaCat cells showed similar adhesion and proliferation on anodized and machined surfaces, a positive interaction between anodized Ti6Al4V ELI surfaces and these two cell lines present in the peri-implant mucosa was observed. Due to the limitations of the present study, further research is necessary to confirm these findings.

Effect of agents affecting bone homeostasis on short- and long-term implant failure

OBJECTIVES

To review the current evidence on the relationship between agents that affect bone homeostasis and dental implant failures.

MATERIALS AND METHODS

Electronic searches for bisphosphonates, denosumab, methotrexate, corticosteroids, romosozumab, sunitinib, and bevacizumab were performed using PubMed, MEDLINE (OVID), EMBASE (OVID), Cochrane Central Register of Controlled Trials (Cochrane Library), Cochrane Oral Health Group Trials Register (Cochrane Library) and Web of Science (Thomson Reuters). Manual searches were also conducted to complement the digital searches for recent issues.

RESULTS

Previous publications suggested that bisphosphonates do not compromise the survival of dental implants. However, one study documented an increased risk of implant failure in patients who had received high-dose of intravenous bisphosphonate therapy after implant rehabilitation. There has been an issue of MRONJ around implants in patients who have successfully received implant therapy before and after antiresorptive therapy, leading to late implant failure. Despite evidence on the detrimental effects of denosumab, methotrexate and corticosteroids on bone metabolism, their role in implant survival is not conclusive.

CONCLUSIONS

At present, there is insufficient evidence to establish a potential connection between agents that affects bone homeostasis and implant failure. However, some studies have reported negative results for implant therapy. In addition, implant-related sequestration in patients who received anti-resorptive therapy, despite of successful osseointegration, is also noticeable. Although limited studies are available at present, clinicians should still carefully consider the potential hazards and take appropriate precautions to minimize the risks associated with the medications and implant therapy.

Ligaplants: Uprising Regimen in the Glebe of Implant Dentistry

A dental implant is an alloplastic framework inserted into the bone, either straight through the alveolar bone or beneath the mucosa or periosteum, to support and hold a permanent or removable dental prosthesis. Osseointegration is a striking phenomenon in which bone directly opposes the implant surface without any interposing collagen or fibroblastic matrix. Although titanium metallic implants were the subject of "osseointegration" at first, it is now used to refer to any biomaterial that can osseointegrate. The science of tissue engineering allows for regenerating complete biological components outside the body for possible replacement treatment or therapy. It uses cells, organic or synthetic scaffold materials, and bioactive molecules. The combination of periodontal ligament (PDL) cells with implant biomaterial is known as Ligaplants. When placed in regions with significant periodontal bone defects, ligaplants can promote the development of new bone. PDL implants, inserted into the missing teeth extraction socket, facilitate surgery. To protect the PDL cell cushion, ligaplants are fitted initially loosely. However, they firmly integrate without interlocking or making direct contact with the bones. Osseointegrated implants affixed directly to the alveolar bone encircling them cannot serve the same purpose as healthy teeth because natural periodontal tissue deteriorates over time. To create a biological connection capable of performing specific physiological tasks, a tissue-engineered PDL must be constructed in conjunction with a dental implant that is well thought out.

Clinical evaluation of the three-dimensional printed strut-type prosthesis combined with autograft reconstruction for giant cell tumor of the distal femur

Propose

This study aimed to describe the design and surgical techniques of a three-dimensional (3D) printed strut-type prosthesis with a porous titanium surface for distal femur giant cell tumors of bone (GCTB) and evaluate the short-term clinical outcomes.

Methods

From June 2018 to January 2021, 9 consecutive patients with grade I or II GCTB in the distal femur underwent extended intralesional curettage followed by 3D-printed strut-type prosthesis combined with autograft reconstruction were retrospectively reviewed to assess their clinical and radiographic outcomes.

Results

All patients were followed up for 30.8 ± 7.5 months (18-42 months) after surgery. The mean affected subchondral bone percentage and the mean subchondral bone thickness before surgery was 31.8% ± 9.6% (range, 18.2% ~50.2%) and 2.2 ± 0.8 mm (range, 1.2-4.0 mm), respectively. At the final follow-up, all the patients were alive without local recurrence; no postoperative complications were observed. Patients had significant improvements in postoperative MSTS-93 score [(26.7 ± 2.4) vs. (18.8 ± 3.7), P < 0.05], and ROM [(122.8° ± 9.1°) vs. (108.3° ± 6.1°), P < 0.05] compared with their preoperative statuses. Furthermore, the mean subchondral bone thickness has increased to 10.9 ± 1.3 mm (range, 9.1-12.1 mm).

Conclusion

3D-printed strut-type prosthesis combined with autograft reconstruction provides acceptable early functional and radiographic outcomes in patients with grade I or II GCTB in distal femur due to the advantages of the prosthesis such as good biocompatibility, osseointegration capacity, and subchondral bone protection. If our early outcomes can be further validated in studies with more patients and sufficient follow-up, this method may be evaluated as an alternative for the treatment of grade I or II GCTB in the distal femur.

Nanotechnology for Dentistry: Prospects and Applications

In the XXI century, application of nanostructures in oral medicine has become common. In oral medicine, using nanostructures for the treatment of dental caries constitutes a great challenge. There are extensive studies on the implementation of nanomaterials to dental composites in order to improve their properties, e.g., their adhesive strength. Moreover, nanostructures are helpful in dental implant applications as well as in maxillofacial surgery for accelerated healing, promoting osseointegration, and others. Dental personal care products are an important part of oral medicine where nanomaterials are increasingly used, e.g., toothpaste for hypersensitivity. Nowadays, nanoparticles such as macrocycles are used in different formulations for early cancer diagnosis in the oral area. Cancer of the oral cavity-human squamous carcinoma-is the sixth leading cause of death. Detection in the early stage offers the best chance at total cure. Along with diagnosis, macrocycles are used for photodynamic mechanism-based treatments, which possess many advantages, such as protecting healthy tissues and producing good cosmetic results. Application of nanostructures in medicine carries potential risks, like long-term influence of toxicity on body, which need to be studied further. The introduction and development of nanotechnologies and nanomaterials are no longer part of a hypothetical future, but an increasingly important element of today's medicine.

The Potential Value of Probiotics after Dental Implant Placement

Dental implantation is currently the optimal solution for tooth loss. However, the health and stability of dental implants have emerged as global public health concerns. Dental implant placement, healing of the surgical site, osseointegration, stability of bone tissues, and prevention of peri-implant diseases are challenges faced in achieving the long-term health and stability of implants. These have been ongoing concerns in the field of oral implantation. Probiotics, as beneficial microorganisms, play a significant role in the body by inhibiting pathogens, promoting bone tissue homeostasis, and facilitating tissue regeneration, modulating immune-inflammatory levels. This review explores the potential of probiotics in addressing post-implantation challenges. We summarize the existing research regarding the importance of probiotics in managing dental implant health and advocate for further research into their potential applications.

Effect of Enterococcus faecalis Biofilm on Corrosion Kinetics in Titanium Grade 4 Alloys with Different Surface Treatments

E. faecalis has been associated with bacteremia, sepsis, and bacterial endocarditis and peri-implantitis. This microorganism can remain in the alveolus even after extraction of the root remnant. This study aimed to evaluate the corrosion on different surfaces of commercially pure titanium (Ti) grade 4 (Ticp-G4) as a function of the bacterial biofilm effect of Enterococcus faecalis. A total of 57 discs were randomly divided according to their surface finish (n = 19). For microbiological analysis (n = 9), the discs were placed in 12-well plates containing E. faecalis culture and incubated at 37 °C for 7 days. The results show that for the intergroup analysis, considering the "electrolyte" factor, there was a difference between the groups. There was greater biofilm formation for the D.A.Zir group, with greater electrochemical exchange for Biofilm, and the presence of biofilm favored greater electrochemical exchange with the medium.

An Optimized Method for Microcomputed Tomography Analysis of Trabecular Parameters of Metal Scaffolds for Bone Ingrowth

Owing to its superior mechanical and biological properties, titanium metal is widely used in dental implants, orthopedic devices, and bone regenerative materials. Advances in 3D printing technology have led to more and more metal-based scaffolds being used in orthopedic applications. Microcomputed tomography (μCT) is commonly applied to evaluate the newly formed bone tissues and scaffold integration in animal studies. However, the presence of metal artifacts dramatically hinders the accuracy of μCT analysis of new bone formation. To acquire reliable and accurate μCT results that reflect new bone formation in vivo, it is crucial to lessen the impact of metal artifacts. Herein, an optimized procedure for calibrating μCT parameters using histological data was developed. In this study, the porous titanium scaffolds were fabricated by powder bed fusion based on computer-aided design. These scaffolds were implanted in femur defects created in New Zealand rabbits. After 8 weeks, tissue samples were collected to assess new bone formation using μCT analysis. Resin-embedded tissue sections were then used for further histological analysis. A series of deartifact two-dimensional (2D) μCT images were obtained by setting the erosion radius and the dilation radius in the μCT analysis software (CTan) separately. To get the μCT results closer to the real value, the 2D μCT images and corresponding parameters were subsequently selected by matching the histological images in the particular region. After applying the optimized parameters, more accurate 3D images and more realistic statistical data were obtained. The results demonstrate that the newly established method of adjusting μCT parameters can effectively reduce the influence of metal artifacts on data analysis to some extent. For further validation, other metal materials should be analyzed using the process established in this study.

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.

Osseointegration of Dental Implants in Patients with Congenital and Degenerative Bone Disorders: A Literature Review

Aims and Objectives

The aim of this study was to describe the mechanism of dental implants osseointegration in patients with congenital and degenerative genetic bone disorders.

Materials and Methods

A PubMed and Scopus documents search was carried out between November 2021 in the, using words such as "osseointegration," "degenerative disease," "congenital disease," and "dental implants."

Results

The thirteen articles selected dealt with dental implants osseointegration in patients with congenital and degenerative bone disorders. The influence and repercussion of these diseases on the bone system, as well as the osseointegration process were described from healing to bone remodeling. In addition, certain articles described some considerations to improve the osseointegration process in patients suffering from these types of conditions.

Conclusions

Within the limitations of this literature review we can conclude that osseointegration in patients with ectodermal dysplasia and osteoporosis could be achieved. However, the planning process for dental implant placement in these patients should be more meticulous and individualized considering the degree of tissue involvement as well as the patient's age and skeletal development compared to systemically healthy patients.

Preparation, modification, and clinical application of porous tantalum scaffolds

Porous tantalum (Ta) implants have been developed and clinically applied as high-quality implant biomaterials in the orthopedics field because of their excellent corrosion resistance, biocompatibility, osteointegration, and bone conductivity. Porous Ta allows fine bone ingrowth and new bone formation through the inner space because of its high porosity and interconnected pore structure. It contributes to rapid bone integration and long-term stability of osseointegrated implants. Porous Ta has excellent wetting properties and high surface energy, which facilitate the adhesion, proliferation, and mineralization of osteoblasts. Moreover, porous Ta is superior to classical metallic materials in avoiding the stress shielding effect, minimizing the loss of marginal bone, and improving primary stability because of its low elastic modulus and high friction coefficient. Accordingly, the excellent biological and mechanical properties of porous Ta are primarily responsible for its rising clinical translation trend. Over the past 2 decades, advanced fabrication strategies such as emerging manufacturing technologies, surface modification techniques, and patient-oriented designs have remarkably influenced the microstructural characteristic, bioactive performance, and clinical indications of porous Ta scaffolds. The present review offers an overview of the fabrication methods, modification techniques, and orthopedic applications of porous Ta implants.

A novel implant surface modification mode of Fe3O4-containing TiO2 nanorods with sinusoidal electromagnetic field for osteoblastogenesis and angiogenesis

Implants made of Ti and its alloys are widely utilized in orthopaedic surgeries. However, insufficient osseointegration of the implants often causes complications such as aseptic loosening. Our previous research discovered that disordered titanium dioxide nanorods (TNrs) had satisfactory antibacterial properties and biocompatibility, but TNrs harmed angiogenic differentiation, which might retarded the osseointegration process of the implants. Magnetic nanomaterials have a certain potential in promoting osseointegration, electromagnetic fields within a specific frequency and intensity range can facilitate angiogenic and osteogenic differentiation. Therefore, this study used Fe₃O₄ to endow magnetism to TNrs and explored the regulation effects of Ti, TNrs, and Fe₃O₄-TNrs under 1 ​mT 15 ​Hz sinusoidal electromagnetic field (SEMF) on osteoblastogenesis, osseointegration, angiogenesis, and its mechanism. We discovered that after the addition of SEMF treatment to VR-EPCs cultured on Fe₃O₄-TNrs, the calcineurin/NFAT signaling pathway was activated, which then reversed the inhibitory effect of Fe₃O₄-TNrs on angiogenesis. Besides, Fe₃O₄-TNrs with SEMF enhanced osteogenic differentiation and osseointegration. Therefore, the implant modification mode of Fe₃O₄-TNrs with the addition of SEMF could more comprehensively promote osseointegration and provided a new idea for the modification of implants.