Search Results (110)

Objectives: To evaluate the influence of implant–abutment connection design, implant diameter, and simulated marginal bone loss on fracture resistance and failure patterns of dental implant systems. Materials and Methods: A total of 180 implant–abutment assemblies were tested, including Morse taper (MT) and internal hex (IH) connections with diameters of 3.5, 4.0, and 5.0 mm. Implants were embedded at two simulated bone levels (0 and 3 mm) and loaded at 30° until failure, in accordance with ISO 14801:2015. Fracture resistance (N) was analyzed using three-way ANOVA. Results: Connection type, implant diameter, bone level, and their interactions significantly affected fracture resistance (p < 0.001). Internal hex implants showed a marked diameter-dependent increase in resistance and greater reduction under simulated bone loss, particularly in reduced diameters. In contrast, Morse taper implants demonstrated similar resistance values regardless of implant diameter or bone level. Failure patterns also differed between systems: internal hex implants exhibited cervical implant fractures in reduced diameters, whereas Morse taper implants showed progressive abutment deformation and/or abutment fracture without implant body fracture. Conclusions: Implant fracture resistance is strongly influenced by implant–abutment connection geometry. Within the limitations of this static in vitro study, MT systems demonstrated diameter-independent mechanical stability and prosthetic-controlled failure patterns, whereas IH systems were highly sensitive to diameter reduction and simulated bone loss. Full article

Marginal bone preservation around osseointegrated dental implants continues to represent a critical challenge in modern implant dentistry. To address this issue, subcrestal implant placement along the apico-coronal axis has been proposed as a reliable clinical strategy aimed at reducing the risk of implant thread exposure within the oral environment. In the present study, 38 healthy patients were treated with either bone-level implants (BLG-Control) or implants positioned 2 mm subcrestally (SCG-Test). All implants featured an internal conical connection and a platform-switching design. In addition, implants in the test group were restored using an immediate tissue-level abutment following the one-time abutment (OTA) protocol. Marginal bone modifications (MBMs) were evaluated through standardized radiographic examinations performed at surgery (T0), implant loading (T1), and after 6 (T2), 12 (T3), 24 (T4), and 36 (T5) months of functional loading. MBMs, meaning the overall changes in the radiographic bone structure over time, were categorized as bone loss (BL) when occurring apical to the implant neck, and as bone remodeling (BR) when detected coronally to the implant neck. Clinical parameters, including probing pocket depth (PPD), bleeding on probing (BoP), and plaque index (PI), were also recorded and analyzed throughout the follow-up period. At the 36-month evaluation, mean MBM values were 0.61 mm for the test group and 0.58 mm for the control group. After three years of follow-up, the test group demonstrated a mean PPD of 2.03 mm, compared with 2.78 mm in the control group. Bleeding on probing was recorded at 13% in the test group and 11% in the control group, while plaque index values were 11% and 5%, respectively. Within the limitations of the present investigation, implants placed 2 mm subcrestally and characterized by an internal conical connection combined with platform switching demonstrated favorable clinical and radiographic outcomes over a short- to medium-term observation period of three years. When compared with equicrestally positioned implants, the subcrestal approach seemed to favor the peri-implant hard tissue conditions while reducing the possibility of marginal bone loss below the implant neck. However, one should bear in mind that this clinical behavior applies specifically to the investigated implant design and should be interpreted within the limitations of the present study. Full article

Implant screw loosening remains among the most frequently reported technical complications in implant-supported prostheses and may compromise prosthetic stability, maintenance requirements, and long-term clinical outcomes. Etiology is multifactorial and involves biomechanical, prosthetic, occlusal, and patient-related factors. This narrative review aimed to synthesize medium- and long-term clinical evidence (>5 years whenever available) regarding mechanisms, prevalence, and risk factors associated with screw loosening in implant-supported restorations. A structured literature search was conducted in PubMed, Web of Science, Cochrane Library, and EBSCOhost to identify clinical studies, randomized controlled trials, systematic reviews, and meta-analyses. Evidence regarding preload, implant–abutment connection design, retention type, implant splinting, framework fit, abutment angulation, implant dimensions, occlusal loading, parafunction, full-arch restorations, and torque protocols was critically interpreted. Current evidence indicates that screw loosening is influenced by inadequate preload, unfavorable occlusal forces, cantilevers, angulated abutments, framework misfit, and parafunctional habits. Single-unit and screw-retained restorations appear to exhibit higher complication rates in several studies, although findings remain inconsistent. Internal connections and splinting may improve mechanical stability; however, superiority has not been conclusively demonstrated. Most screw loosening events occur during the early functional period, emphasizing the importance of preload optimization, occlusal control, maintenance, and follow-up. High-quality long-term comparative studies remain limited. Full article

Cutaneous tissue engineering has advanced from simple coverage substitutes to increasingly complex living constructs, yet the field remains constrained by a decisive problem: timely and durable perfusion. Many engineered skin substitutes can appear vascular in static culture or in small-animal models. However, they still fail when blood flow must be established quickly enough to rescue cells across clinically relevant tissue thickness. Rather than re-catalog platforms already summarized in recent reviews, this critical narrative review reframes the field around perfusion as the master functional endpoint rather than vessel density alone. We analyze the vascularization bottleneck as a sequence, internal network formation, host inosculation, flow initiation, and perfusion stability—and use that sequence to reassess biomaterial design, cell-based strategies, immunomodulation, decellularized matrices, bioprinting, microfluidics, and prevascularization. We intentionally distinguish implantable skin substitutes from perfused in vitro platforms such as skin-on-chip systems, arguing that these are linked but non-interchangeable application spaces with different success criteria. Building on this distinction, we propose a research agenda centered on functional benchmarking of perfusion, spatiotemporal coordination of scaffold dynamics, immune–mural–lymphatic–vascular crosstalk, scalable hierarchical vascular fabrication, and predictive human test platforms. The central argument is that translation will depend not on ever more isolated pro-angiogenic interventions but on integrated systems that survive the ischemic interval, connect rapidly, tolerate blood entry, maintain a workable inflow–outflow balance, and remodel into a stable, skin-specific microvasculature. Full article

Biomedical materials, which are engineered to interact safely and effectively with biological systems, serve as the foundation of modern medicine. They facilitate precise diagnostics, targeted therapies, tissue regeneration, and the functional restoration of damaged organs and tissues. Propelled by advancements in materials science, nanotechnology, and clinical understanding, this field is rapidly evolving from passive implants to intelligent, responsive, and bioactive systems. This review summarize recent breakthroughs in four crucial domains: hard-tissue repair, dynamic wound healing, spatiotemporally controlled drug delivery, and advanced surface engineering. This article rigorously assesses the persistent translational barriers, particularly the disparity between in vitro biocompatibility assays and clinical performance, the scalability constraints in manufacturing, and the fragmentation in regulatory frameworks and international standards. By connecting fundamental innovation with real-world clinical needs, this review functions as both a strategic reference for researchers and a practical resource for clinicians exploring the next generation of biomedical materials. Full article

Maxillofacial defects impair facial aesthetics and oral function, arising from trauma, tumor resection, or congenital anomalies; however, reconstruction using Computer-Aided Design (CAD) and autologous grafts remains complex and time-intensive, and is associated with donor-site morbidity. Although deep learning (DL) has advanced automated reconstruction, existing models often address isolated tasks, lack integrated multi-scale feature learning, and rely on small datasets. This study proposes the Maxillofacial Implant-generation Network (MaxI-Net), a fast, resource-efficient three-dimensional DL framework for end-to-end maxillofacial defect reconstruction and patient-specific implant generation, with a completion step of cavity filling within the assembly. The model employs a 3D encoder–bottleneck-decoder architecture integrating hybrid dilated convolutions, residual connections, squeeze-and-excitation (SE) blocks, and 3D Convolutional Block Attention Modules (CBAM) with multi-scale feature fusion. It was trained on 921 Cone Beam-Computed Tomography (CBCT) scans, augmented to 11,973 maxillary defect pairs, using Dice loss and Adam optimisation with Automatic Mixed Precision, and benchmarked against UNet, UNETR, SegResNet, and SwinUNETR. MaxI-Net achieved the following: superior Dice Similarity Coefficient (DSC) = 0.778; 95th percentile Hausdorff Distance (HD95) = 3.453 mm; DSC Standard Deviation (SD) = 0.094; 95% confidence interval (CI) for mean DSC: 0.775–0.782). It was statistically validated against all competing architectures via pairwise Wilcoxon signed-rank tests, with significant DSC improvements confirmed across all comparators (p < 0.001) and rank-biserial effect sizes ranging from r = 0.250 against the closest competitor SegResNet* with high efficiency (0.06 s/volume; 9.6 min/epoch). Internal cavity filling of the generated implants was performed as a brief manual post-processing step in Autodesk Fusion 360 prior to biomechanical validation. Biomechanical validation using a finite element analysis (FEA) of polyether–ether–ketone (PEEK) implants (~26.53 g) showed 41% stress reduction under physiological loads (100–400 N), predicting a ~9.2-year lifespan. Full article

Microleakage at the implant–abutment interface represents a potential pathway for bacterial penetration and may contribute to peri-implant inflammation, marginal bone loss, and mechanical complications such as screw loosening. The increasing clinical use of compatible prosthetic abutments as cost-effective alternatives to original components has raised concerns regarding their fit, sealing capacity, and mechanical stability at this interface. The aim of this in vitro study was to evaluate differences in sealing capacity and torque loss between original and non-original abutments in a mixed internal connection implant system and to investigate the applicability of a novel quantitative approach for assessing microleakage based on a hydraulic conductance perfusion system. Nine abutments, including four multi-unit and five screw-retained cementable abutments, were connected to Straumann Bone Level implants at two tightening torques (5 N·cm and 35 N·cm). Microleakage was quantified by measuring fluid transport across the implant–abutment interface using the perfusion system, and removal torque values were recorded after testing. Non-original abutments exhibited significantly greater microleakage than original abutments at both torque levels. Microleakage increased significantly when the installation torque was reduced to 5 N·cm. At the manufacturer-recommended torque, screw-retained cementable abutments demonstrated higher microleakage than multi-unit abutments. Non-original abutments also showed significantly greater torque loss. These findings suggest that original abutments provide improved sealing capacity and mechanical stability at the implant–abutment interface, while the hydraulic conductance perfusion system represents a promising quantitative tool for investigating microleakage. Full article

The increasing prevalence of peri-implantitis has led to a growing clinical use of implantoplasty, a procedure involving intraoral machining of the dental implant surface to remove biofilm. The absence of standardized clinical protocols may contribute to premature fatigue failure of dental implants. The present study aimed to evaluate the influence of machining depth on the cyclic mechanical behavior of dental implants. A total of 250 commercially pure grade 4 titanium dental implants were distributed into four groups according to machining depth: untreated (original), 0.2 mm, 0.4 mm, and 0.6 mm wall reduction. The implant system featured an internal connection with a thread height of 0.4 mm. Finite element analysis was performed for each machining depth to evaluate von Mises stress distribution and simulate fatigue behavior. The numerical models were validated through experimental fatigue testing using a servo-hydraulic MTS Bionix testing machine under ISO 14801:2016 conditions, showing a high correlation between simulated and experimental results (correlation coefficients > 0.9). The results indicated that maximum von Mises stresses were concentrated at the junction between the implant thread and the implant body. The fatigue limit of the untreated implants was approximately 351 N. Implants subjected to 0.4 mm machining exhibited a fatigue limit of 301 N, whereas lower fatigue limits were observed for 0.2 mm (255 N) and 0.6 mm (185 N) reductions. These findings suggest a significant mechanical effect of thread removal: 0.4 mm implantoplasty may provide improved fatigue performance compared to 0.2 mm, potentially due to reduced stress concentration at the thread–body junction. At high applied loads, fracture occurred in the coronal region of the implant, whereas at lower loads failure shifted to the implant–abutment connection. Although a good agreement between numerical and experimental results was observed, these findings should be interpreted with caution due to the in vitro testing conditions and the assumptions inherent to the finite element simulations. Therefore, while the results suggest that implantoplasty depth should not exceed the original thread height, further validation under clinically relevant conditions is required to confirm its impact on long-term mechanical reliability. Full article

Inter-implant distance (IID) is crucial for peri-implant bone preservation and long-term implant success. Traditionally, a minimum IID of 3 mm is recommended to limit marginal bone loss, although the biomechanical effect of smaller distances remains debated and may depend on multiple biological, prosthetic, and surgical factors. This study uses finite element analysis (FEA) to evaluate the effect of IID on stress distribution in peri-implant bones of D3 and D4 quality, considering crestal versus subcrestal implant placement, and interpreting results within Frost’s mechanostat theory. Implants with an internal conometric connection were modeled within simulated D3 and D4 mandibular bone blocks. IID values of 3 mm, 1.5 mm, and 1 mm were analyzed under masticatory load. Von Mises stresses in cortical and trabecular bone were compared against biomechanical thresholds (2 MPa disuse and 20 MPa remodeling limit). Results: Cortical stress increased with decreasing IID, more pronounced in crestal placement. In D3 bone, maximum cortical stress rose from 7.2 MPa (3 mm IID) to 16.5 MPa (1 mm IID) under crestal placement, while remaining within the mechanostat-based thresholds adopted in the present stress-interpretation framework. In D4 bone, cortical stress approached 20 MPa at 1 mm IID under crestal placement, indicating a less favorable mechanical condition within the interpretive framework adopted. Subcrestal placement reduced cortical stresses in both bone qualities. Trabecular stress remained stable in D3 (~1.7–8 MPa) and increased moderately in D4 (~up to 13 MPa). Conclusions: Within the limitations of this preclinical finite element study, decreasing inter-implant distance was associated with increased cortical stress, while subcrestal placement was associated with lower cortical stress than crestal placement. These findings should be interpreted only as comparative computational results, and no direct clinical conclusion can be drawn regarding the acceptability of a 1 mm inter-implant distance. Full article

Custom-made subperiosteal implants are increasingly used in clinical cases where significant bone loss due to trauma or disease renders conventional endosseous implant placement unfeasible. This study investigated how different internal structural designs affect the deformation and stress distribution in mandibular subperiosteal implants under clinically relevant loading conditions. An idealized implant geometry was defined based on average human mandibular dimensions, and four configurations with identical outer shape and connection features were created, differing only in sidewall architecture (solid, top-relieved, top-relieved with lateral perforations, and top-relieved lattice framework). All specimens were manufactured by metal additive manufacturing and evaluated using cone-beam computed tomography (CBCT). Mechanical testing was performed in two stages: (i) cyclic loading consisting of 500 bite cycles at an overall force of ~326–350 N and (ii) a single static high-load event of 2000 N, applied parallel to the fixation pin axes. CT datasets acquired before and after each stage were compared to detect permanent deformation. No measurable residual deformation was identified in any configuration; the only observed macroscopic change was an adhesive-bond limitation in one case, rather than structural yielding of the implant. Finite element analysis further supported these findings by identifying localized stress concentrations mainly at the implant–prosthetic interface and by revealing the load-transfer zones that govern the mechanical response. Overall, the results indicate that lightweight, perforated, and lattice-based internal designs can preserve global structural integrity across physiological and supra-physiological load ranges while enabling design optimization to improve stress distribution. Full article

Prosthetic factors, including abutment angulation and the crown–implant ratio (CIR), have been suggested to influence peri-implant marginal bone loss; however, their long-term effects remain unclear. This study aimed to evaluate the pattern of peri-implant bone loss over 2 years and to analyze the clinical relevance of abutment angulation and CIR. A total of 200 posterior internal-connection implants placed between 2017 and 2021 were retrospectively evaluated using standardized periapical radiographs taken at baseline, 6 months, 1 year, and 2 years after loading. Bone level changes were measured mesially and distally and average per implant. Patients were categorized according to abutment angulation (<30° or ≥30°) and CIR (<1:1.5 or ≥1:1.5). The mean marginal bone loss increased during the first year (0.61 mm at 6 months to 1.08 mm at 1 year) and remained stable thereafter (1.12 mm at 2 years). Significantly greater bone loss was observed in implants restored with abutment angulation ≥ 30° (p < 0.05), whereas CIR showed no significant association at any time point (p > 0.05). No interaction effect was found between the two variables. Most peri-implant bone remodeling occurred within the first year after loading, followed by a stable phase. Abutment angulation of ≥30° was associated with increased bone loss, while CIR alone did not demonstrate clinical significance. When possible, minimizing abutment angulation may help improve long-term peri-implant bone stability. Full article

Introduction: The fracturing of abutment screws is a recurrent technical complication in implant-supported prostheses that may compromise prosthetic maintenance. Although multiple retrieval approaches have been described, comparative data under controlled experimental conditions remain limited. Materials and Methods: This in vitro pilot study evaluated the retrievability of fractured abutment screws when using three commonly applied instruments: an ultrasonic scaler, a fissure bur, and a screw removal kit. Eighteen implants from a single implant system were embedded in epoxy resin, and abutment screws were fractured under clockwise monotonic torque either with (w/A) or without (w/oA) abutments (n= 3 per retrieval method). Retrieval success and procedure time were recorded. Scanning electron microscopy (SEM) was performed to qualitatively assess deformation of the implant internal hex and screw thread morphology. Results: Fracture torque values were higher in specimens fractured with abutments compared with those without abutments. Fractures induced without abutments appeared to extend deeper within the screw channel, engaging a greater number of internal threads. In this pilot study, a shorter retrieval time was observed with the screw removal kit and fissure bur compared with the ultrasonic scaler, although retrieval outcomes varied between specimens. SEM observations suggested differing patterns of internal hex deformation between the retrieval techniques. Conclusions: Within the limitations of this in vitro pilot study, different retrieval approaches demonstrated characteristic mechanical behaviors and deformation patterns in the implant internal connection. These preliminary findings provide descriptive insight into the retrievability of fractured screws and may serve as a basis for future studies with larger sample sizes and clinically relevant fracture models. Full article

Background/Objectives: Surgical treatment of chronic osteomyelitis of the proximal tibia is challenging due to limited soft tissue coverage, poor blood supply, and the weight-bearing function of the bone. Moreover, structural instability following curettage may necessitate fixation with metallic implants, which carries a risk of biofilm formation and often requires multi-stage surgeries. Methods: To address these challenges, we developed a new surgical technique combining an anterior approach with establishment of bone marrow communication via intramedullary reaming. The anterior approach provides central access to the infection site, minimizing cortical and cancellous bone loss and eliminating the need for internal fixation. Intramedullary reaming connects the infection site to the systemic circulation, enhancing local blood supply, facilitating intravenous antibiotic delivery, and promoting host immunity. Results: Fourteen patients with proximal tibia osteomyelitis were analyzed. The new surgical technique enabled precise targeting of the infection site, substantially reduced unnecessary bone loss, and eliminated the need for internal fixation. Excluding five cases with Cierny–Mader (C-M) classification IV that required fixation due to inherent structural instability, all nine cases with C-M classification III were treated without internal fixation. Two out of three patients with severe post-traumatic osteomyelitis following Gustilo–Anderson type III open fractures were successfully cured. At a mean follow-up of 53.7 months (range: 2.6–104.9 months), 11 of 14 patients were completely cured with a single surgical intervention, corresponding to a 78.6% cure rate. Conclusions: This new surgical approach enables one-step surgery, avoids the risks of biofilm formation associated with additional fixation, and enhances treatment efficacy through enhancing host immunity, representing an effective strategy for managing proximal tibia osteomyelitis. Full article

The rapid evolution of healthcare technology is being driven by advancements in Micro-Electro-Mechanical Systems (MEMS), BioMEMS (Biological MEMS), and the expanding concept of the Internet of Bodies (IoB). This review explores the convergence of these three domains and their transformative impact on personalized medicine (PM), with a focus on smart, connected biomedical devices. Starting from the historical development of MEMS for medical sensing and diagnostics, the review traces the emergence of BioMEMS as biocompatible, minimally invasive solutions for continuous monitoring and real-time intervention. The integration of such devices within the IoB ecosystem enables data-driven, remote, and predictive healthcare, offering tailored diagnostics and treatment for chronic and acute conditions alike. The paper classifies IoB-associated technologies into non-invasive, invasive, and incorporated devices, reviewing wearable systems such as smart bracelets, e-tattoos, and smart footwear, as well as internal devices including implantable and ingestible. Alongside these opportunities, significant challenges persist, particularly in device biocompatibility, data interoperability, cybersecurity, and ethical regulation. By synthesizing recent advances and critical perspectives, this review aims to provide a comprehensive understanding of the current landscape, clinical potential, and future directions of MEMS, BioMEMS, and IoB-enabled personalized healthcare. Full article

Background: Dental implants are widely used to replace missing teeth, particularly in aesthetically sensitive areas. The implant’s macrogeometry is crucial for ensuring primary stability and successful osseointegration. Internal conical connections and reactive surfaces on implants have shown positive outcomes in tissue and bone stability. In response, a hybrid conical dental implant was designed to address a variety of clinical scenarios. Materials and Methods: This pilot study evaluated the performance of the hybrid conical implant using histological and micro-CT analysis in a preclinical model with immediate loading. Five implants were placed in a mongrel dog, and histomorphometric and micro-CT assessments were performed after 60 days of healing. Results: Analysis showed a high degree of osseointegration, with BIC at 61.56% and BT/TV at 77%. Micro-CT confirmed these findings, with nBIC at 82.20%. Vertical measurements indicated stable crestal bone. Peri-implant tissue displayed organized supracrestal connective tissue, without signs of inflammation or bone saucerization. Polarized light microscopy revealed collagen fibers in perpendicular and oblique orientations around the abutment, suggesting mechanical integration and biological sealing despite the absence of a prosthetic crown. Conclusions: Within the limitations of this exploratory study with one animal study, the hybrid conical implant showed favorable biological and structural responses under immediate loading. These preliminary findings provide useful insights for the refinement of implant design, although further investigations in larger preclinical and clinical studies are required before clinical applicability can be confirmed. Full article