Biomechanical Behavior of Narrow Dental Implants Made with Aluminum- and Vanadium-Free Alloys: A Finite Element Analysis

Titanium (Ti) alloys used for narrow dental implants usually contain aluminum (Al) and vanadium (V) for improved resistance. However, those elements are linked to possible cytotoxic effects. Thus, this study evaluated the biomechanical behavior of narrow dental implants made with Al- and V-free Ti alloys by the finite element method. A virtual model of a partially edentulous maxilla received single implants (diameter: 2.7 and 2.9 mm; length: 10 mm) at the upper lateral incisor area, with respective abutments and porcelain-fused-to-metal crowns. Simulations were performed for each implant diameter and the following eight alloys (and elastic moduli): (1) Ti–6Al–4V (control; 110 GPa), (2) Ti–35Nb–5Sn–6Mo–3Zr (85 GPa), (3) Ti–13Nb–13Zr (77 GPa), (4) Ti–15Zr (113 GPa), (5) Ti–8Fe–5Ta (120 GPa), (6) Ti–26.88Fe–4Ta (175 GPa), (7) TNTZ–2Fe–0.4O (107 GPa), and (8) TNTZ–2Fe–0.7O (109 GPa). The implants received a labially directed total static load of 100 N at a 45° angle relative to their long axis. Parameters for analysis included the maximum and minimum principal stresses for bone, and von Mises equivalent stress for implants and abutments. Ti–26.88Fe–4Ta reaches the lowest maximum (57 MPa) and minimum (125 MPa) principal stress values, whereas Ti–35Nb–5Sn–6Mo–3Zr (183 MPa) and Ti–13Nb–13Zr (191 MPa) models result in the highest principal stresses (the 2.7 mm model surpasses the threshold for bone overload). Implant diameters affect von Mises stresses more than the constituent alloys. It can be concluded that the narrow implants made of the Ti–26.88Fe–4Ta alloy have the most favorable biomechanical behavior, mostly by mitigating stress on peri-implant bone.     

Obstructive sleep apnea and the incidence and mortality of gastrointestinal cancers: a systematic review and meta-analysis of 5,120,837 participants

BackgroundEmerging evidence has shown higher overall cancer incidence in patients with obstructive sleep apnea. Gastrointestinal cancers, including esophageal, stomach, liver, pancreas, and colorectal cancers account for 26% of incident cancers. However, the link between gastrointestinal cancers and obstructive sleep apnea is still unclear. We performed a systematic review and meta-analysis (registered PROSPERO CRD42021220836) to investigate the association between obstructive sleep apnea and incidence of gastrointestinal cancer.MethodsWe searched four electronic databases (PubMed, Embase, Cochrane Library, Scopus) and included studies published from inception till 15th November 2020 reporting the association of obstructive sleep apnea with gastrointestinal cancer incidence. Extracted data was meta-analyzed in a random-effects model.ResultsA total of seven studies were included, forming a combined cohort of 5,120,837 patients. Studies which adjusted for demographics and comorbidities were included in meta-analysis. Among four studies with 7–11 years of median follow-up, patients with obstructive sleep apnea experienced increased incidence of colorectal cancer (HR 1.70, 95% CI: 1.48–1.96, I²=22%). Pancreatic cancer incidence was nominally increased in three studies (HR 1.36, 95% CI: 0.88–2.09, I²=96), though this was not statistically significant. There was no association between obstructive sleep apnea and liver cancer incidence among three studies (HR 0.99, 95% CI: 0.81–1.22, I²=84). However, the lack of a statistically significant relationship between obstructive sleep apnea and pancreatic cancer in our meta-analysis does not necessarily imply the true absence of an association.ConclusionsAn increased risk of colorectal cancer was seen in patients with obstructive sleep apnea among studies with long-term follow-up. Further research is required to explore the utility of incorporating obstructive sleep apnea screening into colorectal cancer screening guidelines to identify high-risk individuals and to confirm a possible association of obstructive sleep apnea with pancreatic cancer.PROSPERO RegistrationCRD42021220836     

Mitochondrial DNA Copy Number Is Associated With Treatment Response and Cognitive Function in Euthymic Bipolar Patients Receiving Valproate

BackgroundBipolar disorder (BD) is associated with cognitive impairment and mitochondrial dysfunction. However, the associations among mitochondrial DNA copy number (MCN), treatment response, and cognitive function remain elusive in BD patients.MethodsSixty euthymic BD patients receiving valproate (VPA) and 66 healthy controls from the community were recruited. The indices of metabolic syndrome (MetS) were measured. Quantitative polymerase chain reaction analysis of blood leukocytes was used to measure the MCN. Cognitive function was measured by calculating perseverative errors and completed categories on the Wisconsin Card Sorting Test (WCST). The VPA treatment response was measured using the Alda scale.ResultsBD patients had significantly higher MCN, triglyceride, and C-reactive protein (CRP) levels, waist circumference, and worse performance on the WCST than the controls. Regression models showed that BD itself and the VPA concentration exerted significant effects on increased MCN levels. Moreover, the receiver operating characteristic curve analysis showed that an MCN of 2.05 distinguished VPA responders from nonresponders, with an area under the curve of 0.705 and a sensitivity and specificity of 0.529 and 0.816, respectively. An MCN level ≥2.05 was associated with 5.39 higher odds of being a VPA responder (P = .006). BD patients who were stratified into the high-MCN group had a higher VPA response rate, better WCST performance, lower CRP level, and less MetS.ConclusionsThe study suggests a link between the peripheral MCN and cognitive function in BD patients. As an inflammatory status, MetS might modulate this association.     

Is parotidectomy justified in elderly patients with pleomorphic adenoma? A decision analysis model

PurposeThe value of parotidectomy in older patients is unclear. This study presents a decision model to help resolve this question.Materials & methodsA Markov model with Monte Carlo simulation was used to compare outcomes in patients of different ages with pleomorphic adenoma of the parotid gland treated by surgery or surveillance.ResultsIn 30-year-old patients, surgery conferred a 3.5-year gain in life expectancy whereas in 75-year-olds, it was only 0.74 months. The expected rate of malignant transformation at age 30 years was 6.5% after surgery and 26.5% after surveillance; at age 65, corresponding rates were 0.8% and 10.7%. Sensitivity analysis showed that age was the only parameter that significantly contributed to life expectancy. The benefit of surgery was restricted in older patients.ConclusionOur Markov decision-analysis model suggests that patients older than 65 years with pleomorphic adenoma have a limited survival advantage with surgery compared to surveillance.     

Atezolizumab and bevacizumab-induced encephalitis in advanced hepatocellular carcinoma: Case report and literature review

Introduction:On the basis of the results of the IMBRAVE-150 trial, the combination of atezolizumab, a programmed cell death ligand 1 (PD-L1) antibody, as well as bevacizumab, a vascular endothelial growth factor (VEGF) antibody, represents a promising novel first-line therapy in patients with advanced hepatocellular carcinoma (HCC). Despite favorable safety data, serious adverse events have been described. However, central nervous system complications such as encephalitis have rarely been reported. We present the case of a 70-year-old woman with hepatitis C virus (HCV)-related liver cirrhosis and advanced HCC who developed severe encephalitis after only one cycle of atezolizumab/bevacizumab.Patient concerns:Ten days after administration, the patient presented with confusion, somnolence, and emesis. Within a few days, the patient''s condition deteriorated, and mechanical ventilation became necessary.Diagnosis:Cerebrospinal fluid (CSF) analysis showed increased cell count and elevated protein values. Further work-up revealed no signs of an infectious, paraneoplastic, or other autoimmune cause.Intervention:Suspecting an atezolizumab/bevacizumab-related encephalitis, we initiated a high-dose steroid pulse therapy as well as repeated plasmapheresis, which resulted in clinical improvement and remission of CSF abnormalities.Outcome:Despite successful weaning and transfer to a rehabilitation ward, the patient died of progressive liver cancer 76 days after initial treatment with atezolizumab/bevacizumab, showing no response.Conclusion:This case illustrates that rapid immunosuppressive treatment with prednisolone can result in remission even of severe encephalitis. We discuss this case in the context of available literature and previously reported cases of atezolizumab-induced encephalitis in different tumor entities, highlighting the diagnostic challenges in oncologic patients treated with immune checkpoint-inhibitors.