Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 96
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Am J Orthod Dentofacial Orthop ; 161(6): e507-e523, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35337704

RESUMO

INTRODUCTION: We investigated whether water jet washing with neutral electrolyzed water (NW) can be an easy and safe self-performed cleaning method for oral environments of fixed orthodontic appliance-wearing patients. In line with this, we examined the bactericidal effects and dissolution behaviors of metal elements released from appliances. METHODS: A metal or resin bracket ligated with a metal wire and metal bracket adhered to an apatite-pellet were used as specimens. The bacteria and plaque removal effects of the 30 seconds of NW (30, 100 ppm) jet washing for contaminated specimens were examined via an agar-plate method and the observation of the residual plaque, comparing with other treatments (brushing and flow washing), those treatments with tap water (TW), and flow washings with commercial mouthwashes, Listerine Total Care + (LS) and ConCool F (CC). The amounts of metal released from metal specimens during the 1-week immersion in NW were analyzed and compared with those in TW, LS, and CC. RESULTS: NW jet washing produced larger decreases of surviving bacteria than the treatments with TW and CC (P <0.05) and equal or larger decreases than the treatment with LS (P <0.05). NW jet washing yielded the highest plaque removal level. The amounts of nickel and chromium released from metal specimens after the 1-week immersion in NW (30 ppm) were less than or equal to those with LS. CONCLUSIONS: NW jet washing could be applicable for cleaning fixed orthodontic appliances because of its higher bactericidal effects than the treatments with commercial mouthwashes, inducing no or a slight metal release in actual usage time.


Assuntos
Antissépticos Bucais , Aparelhos Ortodônticos , Humanos , Níquel , Aparelhos Ortodônticos/efeitos adversos , Aparelhos Ortodônticos Fixos , Água
2.
J Pathol ; 247(3): 371-380, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30426510

RESUMO

Immunoglobulins (Igs) consist of two antigen-binding regions (Fab) and one constant region (Fc). Protein A and protein G are bacterial proteins used for the purification of IgG by virtue of their high affinities for the Fc fragment. Rheumatoid factors are autoantibodies against IgG Fc fragments, which are present in the body under physiological conditions. Little is known about the influence of Fc-binding proteins on the pathogenicity of antibody-induced autoimmune diseases. Pemphigoid diseases are a group of autoimmune subepidermal blistering disorders that includes bullous pemphigoid and mucous membrane pemphigoid. IgGs targeting the non-collagenous NC16A domain of the 180-kDa bullous pemphigoid antigen (BP180) are known to induce skin fragility in mice and the depletion of BP180 in keratinocytes. In this study, mAb against NC16A in combination with Fc-binding proteins was found to enhance BP180 depletion. Although mAb against the C-terminus of BP180 does not show pathogenicity in vivo or in vitro, mAb treatment with Fc-binding proteins clearly induced skin fragility in mice and BP180 depletion in keratinocytes. Anti-BP180 mAbs and Fc-binding proteins were colocalized in the cytoplasm and at the basement membrane zone. Cell adhesion strengths were decreased in parallel with BP180 amounts. Clinically, bullous pemphigoid patients had higher rheumatoid factor titers than controls. Anti-BP180 mAb in combination with high-titer rheumatoid factor serum was found to enhance BP180 depletion. Furthermore, saliva from mucous membrane pemphigoid patients contained larger quantities of bacteria and Fc-binding proteins than controls. Our results suggest that Fc-binding proteins (rheumatoid factor or protein G) may enhance the pathogenicity of autoantibodies in pemphigoid diseases. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Autoantígenos/metabolismo , Doenças Autoimunes/imunologia , Colágenos não Fibrilares/metabolismo , Penfigoide Bolhoso/imunologia , Receptores Fc/imunologia , Animais , Anticorpos Monoclonais/imunologia , Autoanticorpos/imunologia , Doenças Autoimunes/patologia , Proteínas de Transporte/imunologia , Células Cultivadas , Feminino , Humanos , Imunoglobulina G/imunologia , Queratinócitos/metabolismo , Masculino , Camundongos Transgênicos , Penfigoide Mucomembranoso Benigno/imunologia , Penfigoide Mucomembranoso Benigno/patologia , Penfigoide Bolhoso/patologia , Fator Reumatoide/sangue , Saliva/imunologia , Colágeno Tipo XVII
3.
Acta Odontol Scand ; 74(1): 67-72, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-25953322

RESUMO

OBJECTIVE: The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. MATERIALS AND METHODS: Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. RESULTS: Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p < 0.05) with one polyamide based polymer (Valplast) and PMMA based polymers (Acrytone and Acron). The other polyamide based polymer (LucitoneFRS), polyester based polymers (EstheShot and EstheShotBright) and polycarbonate based polymer (ReigningN) did not show significant differences (p > 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. CONCLUSION: It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.


Assuntos
Materiais Dentários/química , Bases de Dentadura , Plásticos/química , Resinas Acrílicas/química , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Nylons/química , Maleabilidade , Cimento de Policarboxilato/química , Poliésteres/química , Polietilenotereftalatos/química , Polimerização , Polímeros/química , Polimetil Metacrilato/química , Estresse Mecânico , Sulfonas/química , Propriedades de Superfície
4.
Odontology ; 104(1): 114-8, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25355555

RESUMO

We describe two patients with anti-BP180-type mucous membrane pemphigoid (MMP), who were correctly diagnosed and treated in early stages through the cooperation of dentists and dermatologists. Patient 1 was a 74-year-old woman who visited our dental department due to blisters over the oral mucosa and eruptions on the skin. She had also experienced bleeding of the gingiva and palate mucosa. Biopsy specimens from the oral mucosa revealed detachment of epithelial basement membrane and subepithelial lamina propria with slight chronic inflammation. Direct immunofluorescence (DIF) revealed linear IgG and IgA deposits along the basement membrane zone (BMZ). Indirect immunofluorescence (IIF) using 1 M-NaCl split normal human skin showed binding of IgG and IgA on the epidermal side. On immunoblot analysis, IgG and IgA autoantibodies reacted with the C-terminal protein of BP180. These findings indicated a diagnosis of anti-BP180-type MMP. Patient 2 was a 59-year-old woman who was referred to our dental department with a history of blisters and large erosions on the gingiva. Biopsy specimens from the oral mucosa revealed partial junctional separation at the level of the basement membrane. DIF showed linear depositions of IgG and C3 along the BMZ. IIF, using 1 M-NaCl split normal human skin, revealed circulating anti-BMZ-IgG antibodies bound to the epidermal side. These findings indicated a diagnosis of anti-BP180-type MMP. Both patients were treated successfully with systemic or topical steroids and oral health care. In conclusion, appropriate clinical examination and cooperation among medical specialists are important for the early diagnosis and treatment of patients with recurrent and chronic stomatitis and for their good prognosis.


Assuntos
Mucosa Bucal/patologia , Penfigoide Mucomembranoso Benigno/diagnóstico , Idoso , Membrana Basal/patologia , Biópsia , Feminino , Imunofluorescência , Humanos , Immunoblotting , Pessoa de Meia-Idade , Penfigoide Mucomembranoso Benigno/patologia , Penfigoide Mucomembranoso Benigno/terapia
5.
Gac Med Mex ; 151(2): 270-2, 2015.
Artigo em Espanhol | MEDLINE | ID: mdl-25946540

RESUMO

Pachyonychia congenita is a group of autosomal dominant inheritance pattern disorders characterized by hypertrophic nail dystrophy There are two main clinical subtypes: type 1 and 2. Pachyonychia congenita type 2 is readily differentiated from type 1 by multiple steatocysts and/or presence of natal teeth and can be confirmed by mutations of KRT6B and KRT17. We report the case of a 33-year-o/d female patient with the missense mutation in KRT17 gene (c.280C> T, p.Arg94Cys) and discuss the several clinical features found with this mutation in the literature.


Assuntos
Paquioníquia Congênita/diagnóstico , Adulto , Feminino , Humanos , Paquioníquia Congênita/genética
6.
Acta Odontol Scand ; 72(2): 139-44, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24255964

RESUMO

OBJECTIVE: This study investigated the properties of injection-molded thermoplastic polyester denture base resins. MATERIALS AND METHODS: Two injection-molded thermoplastic polyester denture base resins (polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer) were tested. Specimens of each denture base material were fabricated for flexural properties testing, Charpy impact testing and shear bond testing (n = 10). The flexural strength at the proportional limit, elastic modulus, Charpy impact strength and the shear bond strength of the two denture base materials were estimated. RESULTS: The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin. CONCLUSION: The properties of the injection-molded thermoplastic denture base resins composed of polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer were different from each other. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin.


Assuntos
Resinas Acrílicas , Bases de Dentadura , Poliésteres , Análise de Variância
7.
Acta Odontol Scand ; 72(8): 859-65, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24850507

RESUMO

OBJECTIVE: This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. RESULTS: Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. CONCLUSION: The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.


Assuntos
Materiais Dentários/química , Bases de Dentadura , Resinas Sintéticas/química , Água/química , Absorção Fisico-Química , Adsorção , Módulo de Elasticidade , Humanos , Imersão , Teste de Materiais , Nylons/química , Maleabilidade , Cimento de Policarboxilato/química , Poliésteres/química , Polimerização , Polimetil Metacrilato/química , Estresse Mecânico , Fatores de Tempo
8.
Am J Pathol ; 181(5): 1659-71, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22940071

RESUMO

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in the gene encoding type VII collagen (COL7), a major component of anchoring fibrils in the epidermal basement membrane zone. Patients with RDEB present a low oral hygiene index and prevalent tooth abnormalities with caries. We examined the tooth enamel structure of an RDEB patient by scanning electron microscopy. It showed irregular enamel prisms, indicating structural enamel defects. To elucidate the pathomechanisms of enamel defects due to COL7 deficiency, we investigated tooth formation in Col7a1(-/-) and COL7-rescued humanized mice that we have established. The enamel from Col7a1(-/-) mice had normal surface structure. The enamel calcification and chemical composition of Col7a1(-/-) mice were similar to those of the wild type. However, transverse sections of teeth from the Col7a1(-/-) mice showed irregular enamel prisms, which were also observed in the RDEB patient. Furthermore, the Col7a1(-/-) mice teeth had poorly differentiated ameloblasts, lacking normal enamel protein-secreting Tomes' processes, and showed reduced mRNA expression of amelogenin and other enamel-related molecules. These enamel abnormalities were corrected in the COL7-rescued humanized mice expressing a human COL7A1 transgene. These findings suggest that COL7 regulates ameloblast differentiation and is essential for the formation of Tomes' processes. Collectively, COL7 deficiency is thought to disrupt epithelial-mesenchymal interactions, leading to defective ameloblast differentiation and enamel malformation in RDEB patients.


Assuntos
Ameloblastos/patologia , Diferenciação Celular , Colágeno Tipo VII/deficiência , Esmalte Dentário/crescimento & desenvolvimento , Esmalte Dentário/patologia , Dente/crescimento & desenvolvimento , Dente/patologia , Ameloblastos/metabolismo , Amelogênese , Animais , Calcificação Fisiológica , Criança , Colágeno Tipo VII/metabolismo , Esmalte Dentário/metabolismo , Esmalte Dentário/ultraestrutura , Epidermólise Bolhosa Distrófica/patologia , Epidermólise Bolhosa Distrófica/fisiopatologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Camundongos , Modelos Biológicos , Fenótipo , Dente/metabolismo , Dente/ultraestrutura
9.
Acta Odontol Scand ; 71(3-4): 716-20, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22900745

RESUMO

OBJECTIVE: The aim of this study was to investigate the flexural properties of denture base resins subjected to long-term water immersion. MATERIALS AND METHODS: Four denture base resins (one conventional heat-processed, one microwave energy-processed and two pour-type autopolymerizing) were selected for this study. The specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n = 10). The flexural properties of the denture base resins were measured according to ISO 20795-1. The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the specimens were evaluated. RESULTS: The ultimate flexural strengths of the heat-processed resin and the two pour-type autopolymerizing resins significantly decreased after 6 months water immersion. The flexural strength at the proportional limit of the heat-processed resin significantly decreased after 6 months water immersion, but the microwave energy-processed denture base resin and two pour-type autopolymerizing resins did not change after 6 months water immersion. The elastic moduli of the heat-processed resin, the microwave energy-processed denture base resin and one pour-type autopolymerizing resin significantly increased after 6 months water immersion. CONCLUSION: The flexural properties of denture base resins significantly changed after long-term water immersion.


Assuntos
Dentaduras , Resinas Sintéticas , Água , Análise de Variância , Teste de Materiais
10.
Acta Odontol Scand ; 71(5): 1250-4, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23339746

RESUMO

OBJECTIVE: This study investigated the shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Four injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) were used in this study. The specimens were divided into eight groups according to the type of surface treatment given: (1) no treatment, (2) air abrasion with alumina, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) alumina and 4-META/MMA-TBB resin, (7) tribochemical silica coating or (8) tribochemical silica coating and 4-META/MMA-TBB resin. Half of the specimens in groups 1, 5, 6 and 8 were thermocycled for 10,000 cycles in water between 5-55°C with a dwell time of 1 min at each temperature. The shear bond strengths were determined. RESULTS: The shear bond strengths to the two polyamides treated with alumina, dichloromethane and ethyl acetate and no treatment were very low. The greatest post-thermocycling bond strengths to polyamides were recorded for the specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (PA12: 16.4 MPa, PACM12: 17.5 MPa). The greatest post-thermocycling bond strengths to polyethylene terephthalate copolymer and polycarbonate were recorded for the treatment with alumina and 4-META/MMA-TBB resin (22.7 MPa, 20.8 MPa). CONCLUSION: Polyamide was exceedingly difficult to bond to an autopolymerizing repair resin; the shear bond strength improved using tribochemical silica coating followed by the application of 4-META/MMA-TBB resin. Both polyethylene terephthalate copolymer and polycarbonate were originally easy to bond to an autopolymerizing repair resin. However, with 4-META/MMA-TBB resin, the bond was more secure.


Assuntos
Dentaduras , Polímeros/química , Resinas Sintéticas , Teste de Materiais
11.
J Prosthodont Res ; 67(1): 132-137, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-35431286

RESUMO

Purpose Hydrofluoric acid has been used to remove salivary contamination in dental glass-ceramics before bonding treatment. However, alternative methods are required because hydrofluoric acid is harmful. This study examined the cleaning effects of phosphoric acid and sodium hydroxide on glass-ceramics for bonding pre-treatment.Methods Feldspar porcelain was divided into four groups: (C) cleaned porcelain without any contamination, (S) porcelain contaminated with saliva, (SPA) porcelain cleaned with 37% phosphoric acid after saliva contamination, and (SSH) porcelain cleaned with 10% sodium hydroxide after saliva contamination. Each sample was bonded to the resin cement using a silane-containing primer. They were then subjected to a shear bond strength (SBS) test. Each surface was analyzed by scanning electron microscopy (SEM), contact angle measurements, and Fourier transform infrared spectroscopy (FT-IR).Results The SBS of group SSH was comparable to that of group C but significantly higher than that of groups S and SPA. SEM observations showed that saliva-like structures remained on the samples of groups S and SPA, but not on the SSH group. The contact angles of groups C and SSH were comparable and significantly smaller than those of groups S and SPA, respectively. FT-IR analysis also revealed saliva in groups S and SPA, which was absent in the SSH group.Conclusions The saliva remained on the porcelain even after cleaning with phosphoric acid, and SBS was not restored to the same level as before the contamination. In contrast, sodium hydroxide eliminated saliva and restored SBS to the same level as before contamination.


Assuntos
Colagem Dentária , Porcelana Dentária , Porcelana Dentária/química , Saliva , Hidróxido de Sódio , Ácido Fluorídrico , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Cimentos de Resina/química , Colagem Dentária/métodos , Teste de Materiais , Resistência ao Cisalhamento , Análise do Estresse Dentário
12.
Dent Mater J ; 42(3): 327-335, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-36709988

RESUMO

Phosphoric acid (PA) etchants are widely used for the bonding pretreatment of teeth; however, their influences on the bonding between glass-ceramics and resin cement have not been clarified yet. This study investigated the effect of a thickening agent on the bonding strength between feldspar porcelain treated with a PA etchant and resin cement with a silane coupling agent. The experiments were performed using two PA etchants: commercial one and prepared one consisting a PA aqueous solution and poly(ethylene glycol) thickening agent. The samples were evaluated by shear bond strength testing, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The obtained results revealed that the thickening agent adhered to the porcelain surface and inhibited cement bonding. Meanwhile, PA remained on the surface due to the presence of the thickening agent and activated the silane coupling agent. Overall, the PA etchant did not improve the bond durability.


Assuntos
Colagem Dentária , Porcelana Dentária , Cimentos de Resina/química , Silanos/química , Colagem Dentária/métodos , Propriedades de Superfície , Cerâmica/química , Teste de Materiais , Resistência ao Cisalhamento
13.
Acta Odontol Scand ; 70(4): 297-302, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21793643

RESUMO

OBJECTIVE: This study investigated the effect of thermal shock on the mechanical properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Four thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were tested. Specimens of each denture base material were fabricated according to ISO 1567 and were either thermocycled or not thermocycled (n = 10). The flexural strength at the proportional limit (FS-PL), the elastic modulus and the Charpy impact strength of the denture base materials were estimated. RESULTS: Thermocycling significantly decreased the FS-PL of one of the polyamides and the PMMA and it significantly increased the FS-PL of one of the polyamides. In addition, thermocycling significantly decreased the elastic modulus of one of the polyamides and significantly increased the elastic moduli of one of the polyamides, the polyethylene terephthalate, polycarbonate and PMMA. Thermocycling significantly decreased the impact strength of one of the polyamides and the polycarbonate. CONCLUSIONS: The mechanical properties of injection-molded thermoplastic denture base resins changed after themocycling.


Assuntos
Análise do Estresse Dentário , Bases de Dentadura , Temperatura Alta , Resinas Sintéticas , Módulo de Elasticidade , Teste de Materiais , Fenômenos Mecânicos , Nylons/química , Maleabilidade , Cimento de Policarboxilato/química , Polietilenotereftalatos/química , Resinas Sintéticas/química
14.
Gerodontology ; 29(2): e1086-91, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22260149

RESUMO

OBJECTIVE: This study investigated the fracture resistance of maxillary acrylic resin complete dentures subjected to long-term water immersion. MATERIALS AND METHODS: Maxillary acrylic resin complete dentures were fabricated from five denture base resins. Half of the dentures were stored in water for 50 h, and the other half were kept in water for 180 days before testing. Ten specimens were fabricated per group. The flexural load at the proportional limit (FL-PL) of the dentures was tested. RESULTS: A two-way anova revealed a significant difference in FL-PL because of the denture base material variable. There were no significant differences in FL-PL because of the effect of water immersion and the interaction between the effect of water immersion and the denture base material. The FL-PLs of the dentures fabricated with the two conventional heat-processed resins, the pour-type autopolymerizing resin and the microwave energy-processed resin were not significantly different from each other; they were significantly higher than the light-activated resin in regard to their FL-PL. CONCLUSION: The FL-PLs of the maxillary acrylic resin complete dentures did not change after long-tern water immersion, and the FL-PL of the denture fabricated from the light-activated resin was lower than those of the other materials.


Assuntos
Resinas Acrílicas/química , Materiais Dentários/química , Prótese Total Superior , Água/química , Análise do Estresse Dentário/instrumentação , Bases de Dentadura , Temperatura Alta , Humanos , Imersão , Teste de Materiais , Metacrilatos/química , Metilmetacrilato/química , Metilmetacrilatos/química , Micro-Ondas , Processos Fotoquímicos , Maleabilidade , Polimerização , Polimetil Metacrilato/química , Poliuretanos/química , Estresse Mecânico , Temperatura , Fatores de Tempo
15.
Materials (Basel) ; 15(7)2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35407767

RESUMO

Polymer-infiltrated ceramic network materials (PICNs) have high mechanical compatibility with human enamel. However, the wear properties of PICN against natural human enamel have not yet been clarified. We investigated the in vitro two-body wear behaviors of PICNs and an enamel antagonist. Two PICNs were used: Experimental PICN (EXP) prepared via the infiltration of methacrylate-based resin into the porous silica ceramic network and commercial Vita Enamic (ENA). Two commercial dental ceramics, lithium disilicate glass (LDS) and zirconia (ZIR), were also characterized, and their wear performance was compared to PICNs. The samples were subjected to Vickers hardness tests and two-body wear tests that involve the samples being cyclically impacted by enamel antagonists underwater at 37 °C. The results reveal that the Vickers hardness of EXP (301 ± 36) was closest to that of enamel (317 ± 17). The volumetric wear losses of EXP and ENA were similar to those of LDS but higher than that of zirconia. The volumetric wear loss of the enamel antagonist impacted against EXP was moderate among the examined samples. These results suggest that EXP has wear behavior similar to that of enamel. Therefore, PICNs are mechanically comparable to enamel in terms of hardness and wear and are excellent tooth-restoration materials.

16.
Dent Mater J ; 41(4): 520-526, 2022 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-35264545

RESUMO

This study aimed to develop a novel polymer-infiltrated ceramic network (PICN) composite fabricated via a slip-casting method for a dental training model tooth with machinability compatible to human enamel. A PICN model tooth comprised of silica/acrylic-resin was fabricated via the slip-casting method. A commercial resin-based model tooth and human enamel were used as the control sample. The samples were evaluated based on Vickers hardness, inorganic contents, density, and machinability. The machinability was characterized by a grinding amount obtained from the grinding test using a device equipped with a dental micromotor handpiece with a diamond bur. The properties of the PICN model tooth yielded a silica content of 84.7% and a density of 1.99 g/cm3, and its Vickers hardness (312) was comparable with that of enamel (348). The grinding amount was comparable with that of enamel. The castable PICN model tooth was compatible to enamel in terms of hardness and machinability.


Assuntos
Cerâmica , Polímeros , Resinas Compostas , Esmalte Dentário , Dureza , Humanos , Teste de Materiais , Dióxido de Silício , Propriedades de Superfície
17.
J Funct Biomater ; 13(1)2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-35323232

RESUMO

Poly(methyl methacrylate) (PMMA)-based resins have been conventionally used in dental prostheses owing to their good biocompatibility. However, PMMA-based resins have relatively poor mechanical properties. In the present study, a novel nanoporous silica filler was developed and introduced into PMMA-based resins to improve their mechanical properties. The filler was prepared by sintering a green body composed of silica and an organic binder, followed by grinding to a fine powder and subsequent silanization. The filler was added to photocurable PMMA-based resin, which was prepared from MMA, PMMA, ethylene glycol dimethacrylate, and a photo-initiator. The filler was characterized by scanning electron microscopy (SEM), X-ray diffraction analysis, nitrogen sorption porosimetry, and Fourier transform infrared (FT-IR) spectroscopy. The PMMA-based resins were characterized by SEM and FT-IR, and the mechanical properties (Vickers hardness, flexural modulus, and flexural strength) and physicochemical properties (water sorption and solubility) were evaluated. The results suggested that the filler consisted of microparticles with nanopores. The filler at 23 wt % was well dispersed in the PMMA-based resin matrix. The mechanical and physicochemical properties of the PMMA-based resin improved significantly with the addition of the developed filler. Therefore, such filler-loaded PMMA-based resins are potential candidates for improving the strength and durability of polymer-based crown and denture base.

18.
Dent Mater J ; 41(1): 45-53, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34408119

RESUMO

Monolithic zirconia crowns bonded to zirconia abutments have become more commonly used in the construction of cement-retained implant superstructures. The present study aimed to examine the effects of laser surface treatments on the bond strength of two resin cements to zirconia. Three types of surfaces were examined: untreated, alumina blasted, and ytterbium laser treated; and two types of resin cements: 4-META/MMA-TBB resin cement and composite resin cement. Half of the specimens were subjected to a thermocycling process. Subsequently, a shear bond test was carried out. In addition, surface roughness was measured for each surface type. The results showed that laser treatment increased zirconia surface roughness and that laser treatment significantly increased shear bond strength after the thermocycling of both cement types compared to no treatment. Our experimental results suggested that ytterbium laser surface treatment of zirconia increased the bond strength of resin cements.


Assuntos
Colagem Dentária , Cimentos de Resina , Cerâmica , Lasers , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície , Itérbio , Zircônio
19.
J Prosthodont Res ; 66(2): 296-302, 2022 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-34470984

RESUMO

PURPOSE: Screw-retained implant crowns used as dental implants comprise a zirconia coping and titanium base bonded using resin cement. These devices are prone to debonding failures. This study investigated the bond characteristics of implant materials based on shear bond strength (SBS) and surface characteristics. METHODS: Chemically pure (CP) titanium grade-4 (Ti), Ti-6Al-4V alloy (Ti-6Al-4V), and tetragonal polycrystalline zirconia (zirconia) were evaluated as adherent materials. Plates of each material were polished, primed for the respective resin cements, and cemented using either methyl methacrylate-based resin cement (Super-Bond) or composite-based resin cement (Panavia). The cemented samples were subjected to 10,000 thermocycles alternating between 5 and 55 °C, and the SBS were obtained before and after thermocycling. The sample surfaces were characterized based on surface observations, roughness, and free energy (SFE). RESULTS: The SBSs of all materials bonded using Panavia were significantly compromised during thermocycling and reached zero. Although the SBSs of Ti and Ti-6Al-4V bonded using Super-Bond were not significantly affected by thermocycling, those of zirconia decreased significantly. The bond durability between zirconia and Super-Bond was improved via alumina air-abrasion, which caused no significant loss of SBS after thermocycling. Surface analyses of the air-abraded zirconia validated these results and confirmed that its surface roughness and SFE were significantly increased. CONCLUSION: The bond durability between resin cement and zirconia was lower than that between Ti and Ti-6Al-4V. The alumina air-abrasion pretreatment of zirconia improved the SFE and surface roughness, thereby enhancing bond durability.


Assuntos
Colagem Dentária , Titânio , Ligas , Óxido de Alumínio/química , Colagem Dentária/métodos , Materiais Dentários/química , Teste de Materiais , Cimentos de Resina/química , Resistência ao Cisalhamento , Propriedades de Superfície , Titânio/química , Zircônio
20.
Macromol Rapid Commun ; 32(3): 289-94, 2011 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-21433173

RESUMO

Electrically conductive polymer films with high stretchability and excellent elasticity were simply fabricated by coating a conductive layer on the surface of an elastomer film. The material used for the conductive layer was a high-shear processed poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer (SEBS)/multiwalled carbon nanotubes (MWCNTs) nanocomposite with 20 wt.-% MWCNTs loading. The nanocomposites were first dissolved in toluene to form a stable solution and then were coated onto the SEBS film by spin coating. The alignment of MWCNTs in the coated layer and the interface between the base film and the coated layer were investigated. It was found that almost all the MWCNTs are aligned parallel to the base film and that there is good adhesion between the two layers. The fabricated films show high electrical conductivity and almost same stretchability and elasticity as the base film. Moreover, the films exhibit extremely high electrical conductive retention after applying high strain.


Assuntos
Química/métodos , Condutividade Elétrica , Polímeros/química , Elasticidade , Nanocompostos/química , Nanotubos de Carbono/química , Propriedades de Superfície
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA