RESUMO
The aim of this study was to perform a literature review on the use of finite element modeling (FEM) for the evaluation of the biomechanical behavior of temporomandibular joint replacement (TMJR) devices. An electronic search of online medical and scientific literature database was conducted using selected search terms. The search identified 307 studies, of which 19 were considered relevant to this study. Of the 19 selected studies, 10 (52.6%) investigated the influence of geometry and fixation methods, while two (10.5%) evaluated the behavior of artificial condyle-fossa structures. The TMJR devices assessed in these studies included TMJ Inc. (aka Christensen; 63.2%), Zimmer Biomet (15.7%), Stryker (10.5%), and a theoretical intramedullary condylar component (5.3%); 26.3% of the studies evaluated custom TMJR devices. Such studies provided important data on the distribution of strain and stress through TMJR structural components and surrounding bone by using different software systems and methods. The mean stress values were lower on a custom TMJR condyle-ramus component and the supporting bone than on the stock device. FEM proved to be an accurate and valuable biomechanical simulation tool for studying the current TMJR devices and should be considered a useful tool for the improvement and development of future joint replacement devices.
Assuntos
Artroplastia de Substituição/métodos , Fenômenos Biomecânicos , Análise de Elementos Finitos , Prótese Articular , Articulação Temporomandibular/fisiopatologia , Articulação Temporomandibular/cirurgia , Humanos , Desenho de PróteseRESUMO
This study aimed to assess the literature available on the effects, on peri-implant tissues, of degradation products released from dental implants as a consequence of therapeutic treatment for peri-implantitis and/or of wear-corrosion of titanium. A literature review of the PubMed medline database was performed up to December 31, 2016. The following search terms were used: "titanium wear and dental implant"; "titanium corrosion and dental implant"; "bio-tribocorrosion"; "peri-implantitis"; "treatment of peri-implantitis"; "titanium particles release and dental implant"; and "titanium ion release and dental implant". The keywords were applied to the database in different combinations without limits of time period or type of work. In addition, the reference lists of relevant articles were searched for further studies. Seventy-nine relevant scientific articles on the topic were retrieved. The results showed that pro-inflammatory cytokines, infiltration of inflammatory response cells and activation of the osteoclasts activity are stimulated in peri-implant tissues in the presence of metal particles and ions. Moreover, degenerative changes were reported in macrophages and neutrophils that phagocytosed titanium microparticles, and mutations occurred in human cells cultured in medium containing titanium-based nanoparticles. Debris released from the degradation of dental implants has cytotoxic and genotoxic potential for peri-implant tissues. Thus, the amount and physicochemical properties of the degradation products determine the magnitude of the detrimental effect on peri-implant tissues.
Assuntos
Implantação Dentária Endóssea/efeitos adversos , Implantes Dentários/efeitos adversos , Peri-Implantite/etiologia , Corrosão , Humanos , Interleucina-1beta/metabolismo , Peri-Implantite/metabolismo , Peri-Implantite/terapia , TitânioRESUMO
Two-piece implant systems are mainly used in oral implantology involving an osseointegrated implant connected to an abutment, which supports prosthetic structures. It is well documented that the presence of microgaps, biofilms and oral fluids at the implant-abutment connection can cause mechanical and biological complications. The aim of this review paper was to report the degradation at the implant-abutment connection by wear and corrosion processes taking place in the oral cavity. Most of the retrieved studies evaluated the wear and corrosion (tribocorrosion) of titanium-based materials used for implants and abutments in artificial saliva. Electrochemical and wear tests together with microscopic techniques were applied to validate the tribocorrosion behavior of the surfaces. A few studies inspected the wear on the inner surfaces of the implant connection as a result of fatigue or removal of abutments. The studies reported increased microgaps after fatigue tests. In addition, data suggest that micromovements occurring at the contacting surfaces can increase the wear of the inner surfaces of the connection. Biofilms and/or glycoproteins act as lubricants, although they can also amplify the corrosion of the surfaces. Consequently, loosening of the implant-abutment connection can take place during mastication. In addition, wear and corrosion debris such as ions and micro- and nanoparticles released into the surrounding tissues can stimulate peri-implant inflammation that can lead to pathologic bone resorption.
Assuntos
Projeto do Implante Dentário-Pivô/efeitos adversos , Implantes Dentários/efeitos adversos , Titânio , Corrosão , Dente Suporte/efeitos adversos , Implantação Dentária Endóssea/efeitos adversos , Implantação Dentária Endóssea/instrumentação , Falha de Restauração Dentária , HumanosRESUMO
UNLABELLED: Lipopolysaccharide (LPS) may induce peri-implantitis and implant failure. However, the role of LPS in titanium (Ti) electrochemical behavior remains unknown. We hypothesized that LPS in saliva with different pHs affects Ti corrosion properties. Thirty-six Ti discs (15 mm × 3 mm) were divided into 12 groups according to saliva pH (3, 6.5, and 9) and Escherichia coli LPS concentration (0, 0.15, 15, and 150 µg/mL). Electrochemical tests, such as open circuit potential, potentiodynamic, and electrochemical impedance spectroscopy, were conducted in a controlled environment. Data were evaluated by Pearson correlation and regression analysis (α = 0.05). LPS and pH affected Ti corrosive behavior. In general, lower pH and higher LPS concentration accelerated Ti corrosion. In the control group, the increase of pH significantly reduced the corrosion rate and increased the capacitance of the double layer. In LPS groups, the decrease of pH significantly increased the corrosion rate of Ti. LPS negatively influenced Ti corrosion behavior. ABBREVIATIONS: C(dl), capacitance of double layer; E(corr), corrosion potential; EIS, electrochemical impedance spectroscopy; I(corr), corrosion current density; I(pass), passivation current density; LPS, lipopolysaccharide; OCP, open circuit potential; R(p), polarization resistance; Ti, titanium.
Assuntos
Materiais Revestidos Biocompatíveis/química , Lipopolissacarídeos/química , Titânio/química , Corrosão , Espectroscopia Dielétrica , Capacitância Elétrica , Impedância Elétrica , Eletroquímica , Escherichia coli , Concentração de Íons de Hidrogênio , Modelos Lineares , Teste de Materiais , Análise de Regressão , Saliva Artificial/química , Estatísticas não Paramétricas , Propriedades de SuperfícieRESUMO
Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polymer widely used in orthopedic applications that imply wear and particle generation. We describe here the response of human osteoblast-like MG63 cells after 6 days of culture in contact with artificially generated particles from both UHMWPE polymer and multiwalled carbon nanotubes (MWCNT)/UHMWPE nanocomposites. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision hip arthroplasty surgeries required by wear failure of acetabular cups and diminish particle-induced osteolysis. The results of an in vitro study of viability and proliferation and interleukin-6 (IL-6) production suggest good cytocompatibility, similar to that of conventional UHMWPE (WST-1 assay results are reported as percentage of control +/- SD: UHMWPE = 96.19 +/- 7.92, MWCNT/UHMWPE = 97.92 +/- 8.29%; total protein: control = 139.73 +/- 10.78, UHMWPE = 137.07 +/- 6.17, MWCNT/UHMWPE = 163.29 +/- 11.81 microg/mL; IL-6: control = 90.93 +/- 10.30, UHMWPE = 92.52 +/- 11.02, MWCNT/UHMWPE = 108.99 +/- 9.90 pg/mL). Standard cell culture conditions were considered as control. These results, especially the absence of significant elevation in the osteolysis inductor IL-6 values, reinforce the potential of this superior wear-resistant composite for future orthopedic applications, when compared to traditional UHMWPE.
Assuntos
Proliferação de Células/efeitos dos fármacos , Teste de Materiais , Nanocompostos , Osteoblastos/citologia , Polietilenos/farmacologia , Técnicas de Cultura de Células , Humanos , Osteoblastos/fisiologiaRESUMO
Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polymer widely used in orthopedic applications that imply wear and particle generation. We describe here the response of human osteoblast-like MG63 cells after 6 days of culture in contact with artificially generated particles from both UHMWPE polymer and multiwalled carbon nanotubes (MWCNT)/UHMWPE nanocomposites. This novel composite has superior wear behavior, having thus the potential to reduce the number of revision hip arthroplasty surgeries required by wear failure of acetabular cups and diminish particle-induced osteolysis. The results of an in vitro study of viability and proliferation and interleukin-6 (IL-6) production suggest good cytocompatibility, similar to that of conventional UHMWPE (WST-1 assay results are reported as percentage of control ± SD: UHMWPE = 96.19 ± 7.92, MWCNT/UHMWPE = 97.92 ± 8.29 percent; total protein: control = 139.73 ± 10.78, UHMWPE = 137.07 ± 6.17, MWCNT/UHMWPE = 163.29 ± 11.81 µg/mL; IL-6: control = 90.93 ± 10.30, UHMWPE = 92.52 ± 11.02, MWCNT/UHMWPE = 108.99 ± 9.90 pg/mL). Standard cell culture conditions were considered as control. These results, especially the absence of significant elevation in the osteolysis inductor IL-6 values, reinforce the potential of this superior wear-resistant composite for future orthopedic applications, when compared to traditional UHMWPE.
Assuntos
Humanos , Proliferação de Células/efeitos dos fármacos , Teste de Materiais , Nanocompostos , Osteoblastos/citologia , Polietilenos/farmacologia , Técnicas de Cultura de Células , Osteoblastos/fisiologiaRESUMO
Renal involvement in 13 non-lepromatous and 17 lepromatous leprosy patients were assessed by routine urinalysis, detailed biochemical analysis of blood and urine and by renal histopathological studies and compared with 10 normal healthy controls. The presence of RBC and pus cells were detected in the urinary deposit of only one lepromatous leprosy patient in reactional phase. A reversal of albumin/globulin ratio was observed in 17.6% of non-lepromatous and 15.3% of lepromatous patients. 24 hours urinary excretion of sodium, potassium, chloride and aminonitrogen of the patients were within the normal range. Forth seven percent of the non-lepromatous and 46% of the lepromatous patients had proteinuria. Even though the mean serum creatinine values of the patients showed no difference from that of the normals, the creatinine clearance was low in 82.3% of the non-lepromatous and in all of the lepromatous patients. Serum phosphorus, serum uric acid, urinary phosphate excretion and the renal tubular reabsorption of phosphorus of the patients were normal. Twenty one percutaneous renal biopsy specimens showed nonspecific pathological changes such as nephritis of various varieties in 71.4% of the specimens. Among the lepromatous group renal involvement was observed in 5 out of 9 cases (55.6%) and in the non-lepromatous group 10 out of 12 cases (83.3%). No acid fast bacilli, amyloid and granuloma were seen in any of the renal tissues studied. There was no definite correlation between the type of renal pathology and biochemical changes. None of the patient showed any clinical evidence of renal involvement.