Search Results (12)

Background and Objectives: Free flap reconstruction is the gold standard for complex head and neck defects following oncological ablation. While surgical techniques have improved flap success rates, donor site sensory morbidity remains relatively understudied. The radial forearm free flap (RFFF) and fibula free flap (FFF) are the two most commonly used free flaps for head and neck reconstruction and sensory abnormalities at their donor sites represent a significant but underrecognized source of postoperative morbidity. Materials and Methods: The aim of this study is to systematically review and synthesize the existing evidence on the prevalence, characteristics and assessment methods of sensory abnormalities and pain at the donor sites of RFFF and FFF harvests. A systematic review was conducted according to PRISMA 2020 guidance. PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library, and Google Scholar were searched from inception to 1 October 2025, with additional gray-literature and reference-list screening. Primary studies reporting sensory abnormalities, donor-site pain, neuropathic pain, or cold intolerance after RFFF and/or FFF harvest were included; prior reviews were used for citation tracking and contextual comparison only. Risk of bias was assessed with study-design-specific Joanna Briggs Institute (JBI) checklists, and the level of evidence was classified using the Oxford Centre for Evidence-Based Medicine (OCEBM) framework. Descriptive prevalence summaries and exploratory random-effects pooled estimates were calculated when numerators and denominators could be extracted. Results: From 1247 initially identified records, 73 studies met the inclusion criteria (36 RFFF-specific, 35 FFF-specific, and 2 addressing both flap types). Most studies were observational, and sensory outcomes were frequently secondary endpoints. For RFFF, reported sensory abnormalities ranged from 0% to 100% across extractable studies (median 31.3%; IQR 13.1–55.0%), reflecting differences in definitions, follow-up, and testing; the exploratory pooled prevalence was 34.4% (95% CI 23.6–47.1%; I2 = 88.4%). General donor-site pain ranged from 0% to 36.8% (median 12.0%; pooled 16.0%, 95% CI 9.9–24.8%), whereas Douleur Neuropathique en 4 Questions (DN4)-defined neuropathic pain was 18% in the largest dedicated RFFF study and 18% in a smaller pain-focused study. Cold intolerance ranged from 0% to 40.0% (median 16.2%). For FFF, sensory abnormalities ranged from 0% to 76.3% (median 21.4%; IQR 8.2–46.8%; pooled 24.0%, 95% CI 16.5–33.6%; I2 = 88.6%). General pain ranged from 0% to 72.7% (median 17.5%; pooled 18.8%, 95% CI 13.9–24.9%), and DN4-defined neuropathic pain was 21% in the only dedicated FFF study. Objective testing (quantitative sensory testing [QST], Semmes-Weinstein monofilaments, two-point discrimination, or standardized neurological examination) was used inconsistently, and no included study systematically used nerve conduction studies or electromyography (EMG). Conclusions: Sensory abnormalities and pain after RFFF and FFF harvest appear common, but available estimates remain uncertain because of heterogeneous definitions, follow-up intervals, assessment instruments, and predominantly Level 2b-4 evidence. The literature shows a persistent gap between patient-reported symptoms and objective sensory testing. Future prospective studies would benefit from standardized neuropathic pain screening, structured neurological examination, and QST; however, current data do not support strong causal inferences or a validated treatment algorithm. Full article

Fused Filament Fabrication (FFF) is a widely used additive manufacturing technology due to its versatility, low cost, and broad material compatibility. However, achieving high dimensional accuracy in FFF parts remains challenging because dimensional deviations are affected by material shrinkage, process parameters, and part geometry. This study analyses the dimensional deviations of PLA hollow cylindrical specimens manufactured by FFF, with particular attention to the different behaviour of outer and inner diameters. The methodology combines an iterative design-adjustment procedure with a neural-network-based compensation approach. First, specimens with different geometries were printed and measured to evaluate the evolution of dimensional error after successive design corrections. Then, the influence of print speed and layer thickness was analysed through the volumetric material flow rate, and the resulting data were used to train separate feedforward neural networks for the outer and inner diameters. The results showed that outer and inner diameters followed different deviation trends, confirming that they should be analysed independently. Print speed, layer thickness, and material flow affected dimensional accuracy in different ways depending on the measured diameter. The proposed neural network approach provided a practical means of estimating compensated design diameters within the experimental domain analysed, reducing the need for repeated trial and error adjustments. However, the results should be interpreted within the experimental limits of the study, particularly regarding the use of a single material, a single printer, and a limited validation dataset. Overall, the study provides a practical workflow for improving dimensional accuracy in FFF parts and highlights the importance of diameter-specific compensation strategies. Full article

This study investigates the failure mechanisms and machining performance of 3D-printed H13 tool steel end mills driven by the creation of a Finite Element Analysis (FEA)-based digital twin. The primary objective is to assess the process capability of these tools by integrating CAD and FEA with product design simulation-based data acquisition within a digital manufacturing framework, thereby validating a physical model. This research begins by redesigning a 20 mm end mill into a 6 mm, four-flute configuration, and then FEA simulating H13 tool steel and tungsten carbide (WC) tools. This is carried out to machine Al-6082-T6 under spindle speeds of 5500 rpm and 1500 rpm, with a constant feed rate of 0.5 mm/tooth over 100,000 cycles. The process is integrated with the Siemens Insights hub via Node-RED to replicate the simulation to correlate the CPU signal spikes and enhanced processing capacity, especially in relation to CAD/CAE kernel activities. Based on the simulation insights, two H13 end mills are fabricated using Fused Filament Fabrication (FFF). The first tool, tested at 5500 rpm and a 1100 mm/min feed rate, fractured after 70 mm of cutting. The second trial, using a diamond-coated solid carbide tool at 1500 rpm and 300 mm/min, achieved successful machining with graphene-enhanced coolant. The cutting forces ranged from 300 to 500 N for 3D-printed tools, compared with 150–180 N for the carbide tool. The surface roughness varied between 0.6–1 µm and 4–6 µm for the printed tools, aligning closely with traditional tools (0.5–1 µm). Post-machining analysis using SEM and EDX confirmed tool wear and material changes. This work adopted a methodology to capture and monitor CPU signal spikes via the digital twin platform, enabling real-time comparison with failure thresholds. The results demonstrate the feasibility of using 3D-printed H13 tools for sustainable, customizable machining, offering a pathway for industries to adopt in-house tool design and manufacturing with integrated digital validation. Full article

Background: Mandibular reconstruction poses challenges in achieving functional and aesthetic outcomes. Effective oral rehabilitation is crucial for restoring function and improving quality of life; however, the altered neomandibular anatomy complicates oral hygiene, increasing the risk of peri-implant complications and making successful rehabilitation more difficult. This study introduces a novel approach combining vestibuloplasty with patient-specific implant-retained splints to enhance oral health and improve rehabilitation outcomes. Methods: Three patients underwent mandibular reconstruction with a free vascularized fibula flap (FFF). After 6 months of osseointegration, vestibuloplasty and soft tissue refinement were performed, with a split-thickness skin graft placed on the FFF periosteum. An implant-retained splint was secured to the abutments for two weeks to support soft tissue healing. Implant survival, bone loss, and peri-implant health were evaluated over a 2-year follow-up. Results: A total of 12 implants were placed, primarily in the neomandible (83.3%), with a 100% survival rate. Implant survival was assessed. Implant survival was assessed based on established criteria for clinical success, including stability, presence of pain, bleeding on probing (BOP), pocketdepth, bone loss and lack of peri-implant radiolucency. Functional outcomes included normal mouth opening, laterotrusion, and protrusion. Pocket depths ranged from 3 to 4 mm, except for one implant in cases 1 and 2. The mean BOP was 51.7%. Conclusions: This case series introduces a surgical technique that combines CAD/CAM and vestibuloplasty to optimize dental rehabilitation in mandibular FFF reconstructions, demonstrating safe thinning of soft tissues for improved oral hygiene and survival. Full article

Recent techniques for forming thermoplastics, such as welding, automated fibre placement or additive manufacturing, generate successive rapid heating and cooling cycles that cause the partial melting of crystals during the process. The melting of an interface is essential to guarantee a good molecular diffusion across the welded parts. Nevertheless, no model can correctly predict the melting kinetics and consequently the evolution of the crystalline degree during the layers’ deposition process. The purpose of this paper was to define the melting kinetics depending on the crystallization conditions for polyetheretherketone (PEEK). Firstly, a non-isothermal crystallization model was proposed over a wide range of cooling rates from 0.1 K.s⁻¹ to 150 K.s⁻¹. Experimental results have highlighted a dual-mode behaviour of melting and demonstrated the dependence of melting temperatures on crystallization conditions. Based on these observations, a model was developed to predict the melting behaviour after non-isothermal crystallization. The melting model revealed that after high cooling rates, primary and secondary crystals melt separately at low temperatures, while after slow cooling rates, both structures melt simultaneously at higher temperatures. Finally, the melting model was applied to the FFF thermal cycle to illustrate the influence of process parameters on the melting kinetics during deposition. Full article

There is limited information regarding implant and prosthetic survival after osseous microvascular free flap (OMFF). This case series aims to describe the placement of short and extra short implants in osseous microvascular free flaps to support prostheses, and present an up to 40-month retrospective follow-up. Short and extra short dental implants were placed in six fibula free flaps (FFF) and in two microvascular deep circumflex iliac artery (DCIA) flaps. In total, 27 short and extra short dental implants have been placed into two different types of free flaps. Kaplan–Meyer (K-M) survival analyses were performed to evaluate the survival and success outcomes of implants and prostheses. Out of the eight patients reconstructed with free flap, five were rehabilitated with prostheses, one patient has a temporary prosthesis, and two patients are in the process of prosthetic rehabilitation. Twenty-seven implants were followed up for up to 40 months, and K-M analyses showed 100% implant survival probability (95% confidence interval: 100%), while the implant success probability was 91.0% (95% confidence interval: 68.6–97.7%). Short and extra short dental implants placed in OMFF presented high survival and success rates in a retrospective case series after up to 40 months. Full article

With the rapid pace of advancements in additive manufacturing and techniques such as fused filament fabrication (FFF), the feedstocks used in these techniques should advance as well. While available filaments can be used to print highly customizable parts, the creation of the end part is often the only function of a given feedstock. In this study, novel FFF filaments with inherent environmental sensing functionalities were created by melt-blending poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and pH indicator powders (bromothymol blue, phenolphthalein, and thymol blue). The new PLA-PEG-indicator filaments were universally more crystalline than the PLA-only filaments (33–41% vs. 19% crystallinity), but changes in thermal stability and mechanical characteristics depended upon the indicator used; filaments containing bromothymol blue and thymol blue were more thermally stable, had higher tensile strength, and were less ductile than PLA-only filaments, while filaments containing phenolphthalein were less thermally stable, had lower tensile strength, and were more ductile. When the indicator-filled filaments were exposed to acidic, neutral, and basic solutions, all filaments functioned as effective pH sensors, though the bromothymol blue-containing filament was only successful as a base indicator. The biodegradability of the new filaments was evaluated by characterizing filament samples after aging in soil and soil slurry mixtures; the amount of physical deterioration and changes in filament crystallinity suggested that the bromothymol blue filament degraded faster than PLA-only filaments, while the phenolphthalein and thymol blue filaments saw decreases in degradation rates. Full article

This is a monocentric, retrospective study of patients who underwent successful immediate or delayed maxilla or mandible reconstructions with FFF from January 2005 to December 2021. Panoramic radiograph, computed tomography scans, and cone-beam CTs were analyzed concerning the osseous union of the intersegmental junctions between maxillary or mandibular native jaw and fibular bone. The primary parameter was to estimate the status of osseous union according to osteosynthesis type. A total number of 133 patients (PSI: n = 64, non-PSI: n = 69) were included in the present study. The mean age was 56.7 ± 14.0 (Range: 14.7–82.7); the primary diagnosis was in 105 patients a malignant (78.9%) and in 20 patients a benign (15.0%) tumor. Mandible reconstruction was performed on 103 patients (77.4%), and on 30 patients (22.6%), maxilla reconstruction was performed. The radiographic images provided a rate of incomplete osseous union (IOU) of about 90% in both groups in the first 6 months. Imaging between 6 and 12 months reveals an IOU rate in the non-PSI group of 46.3% vs. 52.5% in the PSI group, between 12 and 24 months, an IOU rate of 19.6% vs. 26.1%, between 24 and 36 months 8.9% vs. 21.7%, and after 36 months the IOU rate decreases to 4.2% vs. 18.2%. Multivariate logistic regression shows that only osteosynthesis type (OR = 3.518 [95%-CI = 1.223–10.124], p = 0.02) and adjuvant radiotherapy (OR = 4.804 [95%-CI = 1.602–14.409], p = 0.005) are independent risk factors for incomplete osseous union. Cox regression revealed that the variables plate-system (Hazard ratio, HR = 5.014; 95 %-CI: 1.826–3.769; p = 0.002) and adjuvant radiotherapy (HR = 5.710; 95 %-CI: 2.066–15.787; p < 0.001) are predictors for incomplete osseous union. In our study, the rate of incomplete bony fusion was significantly higher in the PSI group. Jaw-to-fibula apposition zones were significantly more affected than intersegmental zones. In multivariate analysis, a combination of osteosynthesis with PSI and adjuvant radiotherapy could be identified as a risk constellation for incomplete ossification. Full article

Three-dimensional printing has advantages, such as an excellent flexibility in producing parts from the digital model, enabling the fabrication of different geometries that are both simple or complex, using low-cost materials and generating little residue. Many technologies have gained space, highlighting the artificial intelligence (AI), which has several applications in different areas of knowledge and can be defined as any technology that allows a system to demonstrate human intelligence. In this context, machine learning uses artificial intelligence to develop computational techniques, aiming to build knowledge automatically. This system is responsible for making decisions based on experiences accumulated through successful solutions. Thus, this work aims to develop a neuroevolutionary model using artificial intelligence techniques, specifically neural networks and genetic algorithms, to predict the tensile strength in materials manufactured by fused filament fabrication (FFF)-type 3D printing. We consider the collection and construction of a database on three-dimensional instances to reach our objective. To train our model, we adopted some parameters. The model algorithm was developed in the Python programming language. After analyzing the data and graphics generated by the execution of the tests, we present that the model outperformed, with a determination coefficient superior to 90%, resulting in a high rate of assertiveness. Full article

The aim of this monocentric, retrospective clinical study was to evaluate the status of osseous union in uni- and poly-segmental mandible reconstructions regarding conventional angle-stable manually bent osteosynthesis plates (Unilock 2.0 mm) versus titan laser-melted PSI patient-specific implant’s (PSI). The clinical impact of PSI’s high stiffness fixation methods on bone healing and regeneration is still not well addressed. The special interest was in evaluating the ossification of junctions between mandible and fibula and between osteotomized fibula free flap (FFF) segments. Panoramic radiograph (OPT), computed tomography (CT) scans, or cone-beam CTs (CBCT) of patients who underwent successful FFF for mandible reconstruction from January 2005 to December 2020 were analyzed. A total number of 89 cases (28 females (31.5%), 61 males (68.5%), mean age 58.2 ± 11.3 years, range: 22.8–82.7 years) fulfilled the chosen inclusion criteria for analysis (conventional: n = 44 vs. PSI: n = 45). The present study found an overall incomplete ossification (IOU) rate of 24.7% (conventional: 13.6% vs. PSI: 35.6%; p = 0.017) for mandible to fibula and intersegmental junctions. Between osteotomized FFF segments, an IOU rate of 16% was found in the PSI-group, while no IOU was recorded in the conventional group (p = 0.015). Significant differences were registered for IOU rates in poly-segmental (p = 0.041), and lateral (p = 0.016) mandibular reconstructions when PSI was used. Multivariate logistic regression analysis identified plate exposure and type of plate used as independent risk factors for IOU. Previous or adjuvant radiotherapy did not impact incomplete osseous union in the evaluated study sample. PSI is more rigid than bent mini-plates and shields functional mechanical stimuli, and is the main reason for increasing the rate of incomplete ossification. To enhance the functional stimulus for ossification it has to be discussed if patient-specific implants can be designed to be thinner, and should be divided into segmental plates. This directs chewing forces through the bone and improves physiological bone remodeling. Full article

Fibula free flap (FFF) is widely used in head and neck reconstructive surgery and is considered as a standard and therapy of choice after ablative cancer surgery. The aim of this retrospective monocenter study was to determine the success rates of fibula free flaps for jaw reconstruction after ablative tumor surgery. The disease course of patients who underwent jaw reconstructive surgery with FFF from January 2002 to June 2020 was evaluated regarding the flap success rate. Flap failure was analyzed in detail and categorized into two groups: partial flap failure (PFF) and total flap failure (TFF). A total of 180 free fibular flaps were performed over the last 19 years and a total of 36 flap failures were recorded. TFF occurred in n = 20 (56.6%) and PFF in n = 16 cases (44.4%) cases. No statistically significant differences were found concerning patients’ age at flap transfer, sex, BMI, ASA-Score, preoperative non-virtual or virtual surgical planning (non-VSP vs. VSP), and time of reconstruction (immediately vs. delayed). Duration of hospitalization shows statistically significant differences between both groups (p = 0.038), but no differences concerning operating time and duration on Intensive Care Unit (ICU). Partial flap failure appears to be underreported in literature. Sub- and complete failure of the skin paddle leads to clinical complaints like uncovered bone segments and plate exposure. Partial or complete FFF failure lead to infections on the recipient site and prolonged wound healing and therefore may cause a delay of the beginning of adjuvant radiation therapy (RT). PFF of hard tissue can be induced by RT. Full article

The fibula free flap (FFF) has been a workhorse in maxillofacial reconstruction. High success rates of this technique are reported. However, identifying risk factors for flap failure and analyzing complications can open the way to better patient care. A retrospective analysis was conducted of all FFFs performed over a 20-year period at a low-volume single tertiary center to identify risk factors and postoperative complications. A total of 129 FFFs were included (122 mandible, 7 maxilla). Complete flap failure occurred in 12.4% and partial flap failure in 7.8% of patients. A significant relation was found between younger age and flap failure, and most failures were associated with venous thrombosis. In-hospital surgical complications occurred in 60.5%, in-hospital medical complications in 49.6%, and out-of-hospital complications in 77.5% of patients. The in-hospital reintervention rate was 27.1%, and including salvaged flaps, flap survival rate was 87.6%. Osteomyocutaneous FFF failure (complete 12.4%; partial 7.8%) is an important clinical reality in a low-volume head and neck reconstruction center resulting in an in-hospital reintervention rate of 27.1%. Postoperative complications are frequent, both surgical and out-hospital complications. These results provide a better understanding of the limitations of the FFF in a low-volume center and can be used to optimize care in this kind of setting. Full article