Explore the vast range of titles available.

Polyetheretherketone (PEEK) is a semi-crystalline linear polycyclic thermoplastic that has been proposed as a substitute for metals in biomaterials. PEEK can also be applied to dental implant materials as a superstructure, implant abutment, or implant body. This article summarizes the current research on PEEK applications in dental implants, especially for the improvement of PEEK surface and body modifications. Although various benchmark reports on the reinforcement and surface modifications of PEEK are available, few clinical trials using PEEK for dental implant bodies have been published. Controlled clinical trials, especially for the use of PEEK in implant abutment and implant bodies, are necessary.

Recycling carbon-fiber-reinforced plastics (CFRPs) is crucial for sustainable material utilization, particularly in aerospace applications, where large quantities of prepreg waste are generated. This study investigated the mechanical properties of highly oriented recycled CFRP (rCFRP) molded using vacuum-assisted resin transfer molding (VaRTM), wet-layup, and traditional RTM methods. Recycled carbon fibers (rCFs) obtained via solvolysis and pyrolysis were processed into nonwoven preforms to ensure fiber alignment through carding. The influence of molding methods, fiber recycling techniques, and fiber orientation on mechanical performance was examined through tensile tests, fiber volume fraction (Vf) analysis, and scanning electron microscopy observations. The results indicated that the solvolysis-recycled rCF exhibited superior interfacial adhesion with the resin, leading to a higher tensile strength and stiffness, particularly in the RTM process, where a high Vf was achieved. Wet-layup molding effectively reduced the void content owing to autoclave curing, maintaining stable properties even with pyrolyzed rCF. VaRTM, while enabling vacuum-assisted resin infusion, exhibited a higher void content, limiting improvements in mechanical performance. This study highlights that tailoring the molding method according to the desired performance, such as increasing stiffness potential by enhancing Vf in RTM or improving tensile strength by improving fiber–matrix adhesion in wet-layup molding, is critical for optimizing rCFRP properties, providing important insights into sustainable CFRP recycling and high-performance material design.

The lung volume receiving low-dose irradiation has been reported to increase in volumetric-modulated arc radiotherapy (VMAT) compared with three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal cancer, which raises concerns regarding radiation pneumonitis (RP) risk. This single institutional retrospective cohort study aimed to explore whether VMAT for thoracic esophageal cancer was associated with RP. Our study included 161 patients with thoracic esophageal cancer, of whom 142 were definitively treated with 3DCRT and 39 were treated with VMAT between 2008 and 2018. Radiotherapy details, dose–volume metrics, reported RP risk factors and RP incidence were collected. The RP risk factors were assessed via multivariate analysis. Dose–volume analysis showed that VMAT delivered more conformal dose distributions to the target volume (P < 0.001) and reduced V30 Gy of heart (57% vs 41%, P < 0.001) but increased V5 Gy (54% vs 41%, P < 0.001) and V20 Gy (20% vs 17%, P = 0.01) of lungs compared with 3DCRT. However, the 1-year incidence rates of RP did not differ between the two techniques (11.3% in 3DCRT vs 7.7% in VMAT, P = 0.53). The multivariate analysis suggested that the presence of interstitial lung disease (ILD) (P = 0.01) and V20 Gy of lungs ≥20% (P = 0.008) were associated with RP. Conclusively, VMAT increased the lung volume receiving low to middle doses irradiation, although this might not be associated with RP. Further studies are needed to investigate the effect of using VMAT for delivering conformal dose distributions on RP.

Background/Objectives: Tooth color is key in determining aesthetic appearance during restorative and prosthodontic treatments. To establish a more reliable methodology for shade selection, this study investigated differences in the discrimination and acceptance of tooth color between dental and non-dental professionals, focusing on color attributes such as lightness and chroma. Methods: This study included 30 dentists, 30 dental technicians, 30 patients, and 30 dental students. They were asked to compare pairs of shade tabs with different lightness and chroma from the VITA Toothguide 3D-MASTER® (VITA Zahnfabrik, Bad Säckingen, Germany). The number of answers in which participants could discriminate color differences (discrimination numbers) and answers in which they could not accept color differences (non-acceptance numbers) were recorded. Statistical analysis was performed using Spearman’s rank correlation coefficient, the Mann–Whitney U test, the Kruskal–Wallis test, and multiple regression analysis (p < 0.05). Results: Significant factors influencing lightness discrimination were participant group and age, while those influencing acceptance were subject group and sex. Conclusions: This study revealed differences in the discrimination and acceptance of lightness and chroma between dental and non-dental professionals, particularly concerning lightness. Dental technicians exhibited a higher discrimination ability and stricter acceptance of lightness and chroma, regardless of age. Based on an understanding of these characteristics, appropriate shade selection and adequate communication will be important.

These days, new prosthodontic materials are appearing with the development of digitalization. Among these, the use of polyetheretherketone (PEEK) as the clasp of removable partial dentures has been proposed. The adhesive strength between the PEEK and acrylic resin influences the probability of denture fracture. To investigate the effect of PEEK surface treatments on the shear bond strength to acrylic resin, five surface treatment conditions of PEEK were analyzed: 1. no treatment; 2. ceramic primer application; 3. Al2O3 sandblasting; 4. Rocatec; and 5. Rocatec with ceramic primer application, comparing with a metal primer-treated Co-Cr alloy. Two kinds of autopolymerizing resin (Unifast II and Palapress Vario) were used as bonding materials. The specimens were evaluated to determine the bond strength. Rocatec treatment with ceramic primer application yielded the highest bond strengths (12.71 MPa and 15.32 MPa, respectively, for Unifast II and Palapress Vario). When compared to a metal primer-treated Co-Cr alloy, the bond strength of PEEK to Unifast II was similar, whereas it was about 60% of that to Palapress Vario. Rocatec treatment, combined with ceramic primer, showed the highest bond strength of PEEK to acrylic resin. Treatment of PEEK will enable its use as the clasp of removable dentures and the fixation of PEEK prostheses.

Background Implant-assisted removable partial dentures (IARPDs) have recently become popular, but little information is available on the treatment outcomes based on the Kennedy classification and attachment types. Objective The objective of this review was to evaluate the treatment outcomes of IARPD delivered for distal extension edentulous areas based on the differences in the Kennedy classification and attachment type. Materials and methods English-language clinical studies on IARPD published between January 1980 and February 2020 were collected from MEDLINE (via PubMed), the Cochrane Library (via the Cochrane Central Register of Controlled Trials), Scopus online database, and manual searching. Two reviewers selected the articles based on pre-determined inclusion and exclusion criteria, followed by data extraction and analysis. Results Eighty-one studies were selected after evaluating the titles and abstracts of 2410 papers. Nineteen studies were finally included after the perusal of the full text. Fourteen studies focused on Class I, 4 studies investigated both Class I and II, and only 1 study was conducted on Kennedy’s class II. Eight types of attachments were reported. The ball attachment was the most frequently used attachment, which was employed in 8 of the included studies. The implant survival rate ranged from 91 to 100%. The reported marginal bone loss ranged from 0.3 mm to 2.30 mm. The patient satisfaction was higher with IARPD than with conventional RPDs or that before treatment. The results of prosthetic complications were heterogeneous and inconclusive. Conclusion IARPD exhibited favorable clinical outcomes when used as a replacement for distal extension edentulous areas. The comparison between the clinical outcomes of Kennedy’s class I and II was inconclusive owing to the lack of studies focusing on Kennedy Class II alone. The stud attachment was the most commonly used type in IARPDs. Overall, the different attachment systems did not influence the implant survival rate and patient satisfaction. Further high-quality studies are needed to investigate the attachment systems used in IARPD.

Background/Objectives: Recently, a novel magnetic attachment system was introduced to improve performance. Using the same technology, a new ultra-thin magnetic attachment (UTMA) was possible to produce. This study aimed to evaluate the feasibility of a magnet-retained telescopic partial denture (MTPD) utilizing the new UTMA. Methods: This in vitro study was performed using a titanium master model representing prepared lower first-premolar and second-molar abutment teeth. The inner crowns (ICs) (h: 4 mm, 4° taper) and four-unit MTPDs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) using zirconia. A Ø4 mm UTMA system (magnet assembly and keeper thickness: 0.6 mm and 0.4 mm, respectively) was cemented into the MTPD and the ICs using dual-cure resin cement. A load of 100 N was applied along with 10,000 insertion–removal cycles. The MTPD retentive force was measured before and after every set of 1000 cycles. Stability tests and surface morphology evaluations were conducted before and after cycling. A paired t-test (α = 0.05) was used to observe statistical differences. Results: The average retentive force of the MTPD was 6.86 ± 0.63 N and did not change significantly (p > 0.05) following the load cycles (6.66 ± 0.79 N). The MTPD demonstrated adequate stability under the occlusal load. Minimal deformations were observed on the magnet assemblies, keepers, ICs, and MTPD surfaces after the load tests. Conclusions: Considering the limitations of this study, an MTPD utilizing novel UTMAs fabricated through a digital workflow demonstrated adequate retentive force, stability, and durability for clinical use.

Novel phenylethynyl-terminated addition-type imide oligomers (degree of polymerization, n =4) derived from 1,2,4,5-benzenetetracarboxylic dianhydride, 2-phenyl-4,4′-diaminodiphenyl ether (p-ODA), which has an asymmetric and nonplanar structure, and 9,9-bis(4-aminophenoxy)fluorene were synthesized for use as the matrix resin of fiber-reinforced composites with high heat resistance. The uncured imide oligomers showed good solubility (>30 wt%) in aprotic solvents such as N -methyl-2-pyrrolidone and very low minimum melt viscosity. These excellent properties were achieved using steric hindrance of the pendant phenyl group of p-ODA in a solution or a melted state to prevent the intramolecular/intermolecular interactions of imide oligomer chains. The imide oligomers were converted to crosslinked structures after curing at 370 °C for 1 h. Thermal and rheological properties of the cured resins were characterized by differential scanning calorimetry, thermogravimetric analysis and dynamic rheometry. The glass transition temperature and elongation-at-break of the cured imide resin were found to be almost >350 °C and >15%, respectively. These excellent properties of pyromellitic dianhydride-based and p-ODA-based addition-type aromatic polyimides are promising for applications in highly heat-resistant composites. Novel phenylethynyl (4-phenylethynyl phthalic anhydride) terminated addition-type imide oligomers derived from pyromellitic dianhydride and 2-phenyl-4,4′-diaminodiphenyl ether showed a high solubility and a very low minimum melt viscosity. These imide oligomers were also converted to crosslinked cured resins with Kapton-type backbone structures after curing at 370 °C. The glass transition temperature and elongation-at-break of the cured resins were extremely high (almost 350 °C and >10%, respectively). These epoch-making imide oligomers were found to have excellent processability for molding of fiber-reinforced plastics with high heat resistance.

Background Prognostic factors after treatment for intrahepatic recurrent hepatocellular carcinoma (RHCC) after hepatic resection (Hx) are controversial. The current study aimed to examine the impact of treatment modality on the prognosis of intrahepatic RHCC following Hx. Methods For control of variables, the subjects were 56 patients who underwent treatment for intrahepatic RHCC, three or fewer tumors, each measuring ≤3 cm in diameter without macroscopic vascular invasion (MVI), between 2000 and 2011. Retreatment consisted of repeat Hx (n = 23), local ablation therapy (n = 11) and transarterial chemoembolization or transcatheter arterial infusion (TACE/TAI) (n = 22). We retrospectively investigated the relation between type of treatment for RHCC and overall survival (OS) as well as disease‐free survival (DFS). Results In multivariate (MV) analysis, the poor prognostic factors in DFS after retreatment consisted of disease‐free interval (DFI) (≤1.5 y) (P = .011), type of retreatment (TACE/TAI) (P = .002), age (<65 y old) (P = .0022), perioperative RBC transfusion (P = .025), while those in OS after retreatment were DFI (≤1.5 y) (P < .0001). In evaluation of stratification for type of retreatment, DFS in the repeat Hx group was significantly better than those in the local ablation therapy group or the TACE/TAI group (P = .023 or P < .0001, respectively). Conclusions DFI (≤1.5 y) was an independent poor prognostic factor in both DFS and OS, and repeat Hx for intrahepatic RHCC, few in number and size without MVI, seems to achieve the most reliable local control. Repeat hepatectomy for patient with intrahepatic recurrent hepatocellular carcinoma, few in number and size, after initial hepatectomy may improve recurrence‐free survival, especially in patients with a longer recurrence‐free interval, more than 1.5 y.

Background The aim of this study was to identify the long-term clinical outcome of definitive radiotherapy using three-dimensional conformal radiotherapy (3DCRT) for cervical esophageal squamous cell carcinoma (CESCC). Methods We retrospectively reviewed the medical records of 30 patients with CESCC [clinical stage I/II/III/IV(M1LYM); 3/2/12/13] (TNM 7th edition) who underwent definitive radiotherapy using 3DCRT between 2000 and 2014 in our institution. The median prescribed dose for the gross tumor and metastatic lymph nodes was 60 Gy. Twenty-six patients underwent elective nodal irradiation for the neck node levels III, IV, and VI and for upper mediastinal lymph nodes with a median dose of 40 Gy. Twenty-six patients underwent concurrent chemotherapy. Initial disease progression sites, locoregional control (LRC) rate, overall survival (OS) rate, and toxicities were retrospectively evaluated. A univariate analysis was performed to identify prognostic factors. Results With a median follow-up of 110 months, the 5- and 10-year LRC rates were 43.7% and 37.4%, respectively. The 5- and 10-year OS rates were 48.3% and 40.2%, respectively. Locoregional, distant and both area accounted for 83%, 6% and 11% of the initial progression sites. Unresectable status and M1LYM were significantly associated with poor LRC ( p  < 0.05) and OS ( p  < 0.05). Grade 3 acute non-hematological toxicity occurred in 13.3% of patients. During the follow-up, patients without any disease progression did not need a permanent gastrostomy tube or tracheostomy. Late toxicity events, including hypothyroidism and cardiovascular disease, were observed; 5- and 10-year cumulative incidence rates of grade 2 hypothyroidism and ≥grade 3 cardiovascular disease were 31.6% and 62.5%, and 17.5% and 21.3%, respectively. Conclusions Definitive radiotherapy yields a cure for patients with CESCC while preserving their laryngopharyngeal function. The poor LRC rate in the advanced stage needs to be overcome for a better prognosis. As the incidence of radiation-induced hypothyroidism and cardiovascular disease was not low, long-term survivors should be followed up for these symptoms.