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1.
Am J Dent ; 33(2): 69-73, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32259410

RESUMO

PURPOSE: To evaluate marginal seal, adaptation, surface texture, and bubble presence of pit and fissure sealants when using a novel instrument (C-Shape It) or the manufacturers' supplied applicators for sealant placement into occlusal fissures. METHODS: Extracted molars with occlusal fissures were cleaned with pumice slurry and divided into six groups (n= 10/gp); three treatment and three control. Sealant materials placed included Ultraseal, Delton, and Helioseal. Excess water was removed per manufacturers' instructions. Sealants were applied with each applicator and with the C-Shape It to each group from cusp to cusp without covering marginal ridges, and the polymerization guidelines for photocuring were followed for all the groups. Samples were thermocycled at 500x between 5° and 55°C. Teeth were sectioned in a buccolingual direction with a minimum of four sections per tooth and examined under a light microscope at 50x and scored. RESULTS: Marginal seal, adaptation, penetration ability, surface texture, bubble formation and location of the sealants were analyzed using two-way ANOVA on ranks with a 95% confidence interval. The C-Shape It instrument showed consistently smoother surface texture (P< 0.001), which was statistically significant versus all manufacturers' applicators for all materials. Bubble presence was statistically significantly less with the instrument C-Shape It versus the manufacturers' applicators for all materials (P< 0.001). Results also revealed significant differences in marginal sealant adaptation. CLINICAL SIGNIFICANCE: C-Shape It demonstrated consistent ability to reduce bubbles and improve surface texture and adaptation in occlusal fissures for all pit and fissure products tested.


Assuntos
Infiltração Dentária , Selantes de Fossas e Fissuras , Bis-Fenol A-Glicidil Metacrilato , Dente Molar
2.
Dent Mater ; 36(4): 542-550, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32061442

RESUMO

OBJECTIVE: The use of the BisGMA as base monomer in dental composites has been questioned because of bisphenol A (BPA) is used as raw material in its synthesis, and BPA possess estrogenic potential associated to several health problems. This study describes the synthesis of the trimethacrylate tris(4-hydroxyphenyl)methane triglycidyl methacrylate (TTM) monomer and evaluate its effect when used as base monomer in the formulation of experimental photopolymerizable composite resins. METHODS: The TTM monomer was synthesized by a nucleophilic acyl substitution. Its chemical structure was confirmed via 1H and 13C NMR spectroscopy and FTIR spectroscopy. Experimental composite resins were formulated by mixing TTM, triethyleneglycol dimethacrylate (TEGDMA) and inorganic fillers. A BisGMA/TEGDMA based composite resin was prepared and used as control to compare several physicochemical properties. Cell viability assay was used for cytotoxicity evaluation. RESULTS: TTM was successfully synthesized with quantitative yields. The results showed that the TTM-based composite resin had similar values of flexural strength, elastic modulus, degree of conversion and polymerization shrinkage than the control (p > 0.05). Water sorption and solubility were statistically significantly higher than the control (p < 0.05), however they complied the requirements stablished by the ISO 4049. Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p = 0.345). SIGNIFICANCE: TTM monomer could be potentially useful in the formulation of BisGMA free composite resins, which could mean to minimize the human exposure to BPA.


Assuntos
Resinas Compostas , Ácidos Polimetacrílicos , Bis-Fenol A-Glicidil Metacrilato , Resistência à Flexão , Humanos , Teste de Materiais , Metacrilatos , Polietilenoglicóis , Polimerização , Solubilidade
3.
Braz Oral Res ; 34: e005, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32022224

RESUMO

The purpose of this study was to evaluate the effect of ionizing radiation from high energy X-ray on fluoride release, surface roughness, flexural strength, and surface chemical composition of the materials. The study groups comprised five different restorative materials: Beautifil II, GCP Glass Fill, Amalgomer CR, Zirconomer, and Fuji IX GP. Twenty disk-shaped specimens (8x2 mm) for fluoride release and 20 bar-shaped specimens (25 x 2x 2 mm) for flexural strength were prepared from each material. Each material group was divided into two subgroups: irradiated (IR) and non-irradiated (Non-IR). The specimens from IR groups were irradiated with 1.8 Gy/day for 39 days (total IR = 70.2 Gy). The amount of fluoride released into deionized water was measured using a fluoride ion-selective electrode and ion analyzer after 24 hours and on days 2, 3, 7, 15, 21, 28, 35, and 39 (n = 10). The flexural strength was evaluated using the three-point bending test (n = 10). After the period of measurement of fluoride release, seven specimens (n = 7) from each group were randomly selected to evaluate surface roughness using AFM and one specimen was randomly selected for the SEM and EDS analyses. Data were analyzed with two-way ANOVA and Tukey tests (p = 0.05). The irradiation significantly increased fluoride release and surface roughness for Amalgomer CR and Zirconomer groups (p < 0.05). No significant change in flexural strength of the materials was observed after irradiation (p > 0.05). The ionizing radiation altered the amount of fluoride release and surface roughness of only Amalgomer CR and Zirconomer. The effect could be related to the chemical compositions of materials.


Assuntos
Apatitas/efeitos da radiação , Bis-Fenol A-Glicidil Metacrilato/efeitos da radiação , Resinas Compostas/efeitos da radiação , Fluoretos/química , Cimentos de Ionômeros de Vidro/efeitos da radiação , Radiação Ionizante , Zircônio/efeitos da radiação , Análise de Variância , Apatitas/química , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/química , Resistência à Flexão , Cimentos de Ionômeros de Vidro/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Espectrometria por Raios X , Estatísticas não Paramétricas , Propriedades de Superfície/efeitos da radiação , Fatores de Tempo , Zircônio/química
4.
Niger J Clin Pract ; 23(2): 165-171, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32031090

RESUMO

Aims: The aim of this study is to evaluate the effect of the diode laser used for dentin sensitivity on the clinical success of non-carious cervical lesion (NCCL) restorations restored with different adhesive systems. Methods: 20 NCCLs were restorated with Universal Single Bond (Self Etch) (3M, USA) and Grandio (Voco, Germany), 20 NCCLs were restorated with Universal Single Bond (Total Etch) and Grandio. After diode laser application, 20 NCCLs were restorated with Universal Single Bond and Grandio, 20 NCCLs were restorated with Universal Single Bond (Total Etch) and Grandio. The restorations were clinical evaluated by two examiners at baseline, for 6 and 18 months using modified United States Public Health Service (USPHS) Criteria. Chi-square test was used for statistical analyse. Results: The lowest rates of retention was found in the Group 1. There was no statistically significant difference among the groups in marginal discoloration, marginal integrity, sensitivity (P > 0.05). Conclusion: Diode laser application prior to the restoration of teeth with NCCL don't reduce the retention rate of restorations, may reduce hypersensitivity and may affect the success of restoration. However, further laboratory and clinical studies are required.


Assuntos
Adesivos/farmacologia , Resinas Compostas , Corrosão Dentária , Restauração Dentária Permanente/métodos , Lasers Semicondutores/uso terapêutico , Colo do Dente , Adulto , Bis-Fenol A-Glicidil Metacrilato , Adaptação Marginal Dentária , Sensibilidade da Dentina , Adesivos Dentinários , Feminino , Seguimentos , Humanos , Lasers Semicondutores/efeitos adversos , Masculino , Pessoa de Meia-Idade
5.
Dent Mater ; 36(3): 468-477, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32005546

RESUMO

OBJECTIVE: The aim of this study was to investigate the influence of the photoinitiator system on the polymerization kinetics of methacrylamide-based monomers as alternatives to methacrylates in adhesives dental-based materials. METHODS: In total, 16 groups were tested. Monofunctional monomers (2-hydroxyethyl methacrylate) - HEMA; (2-hydroxy-1-ethyl methacrylate) -2EMATE, (2-hydroxyethyl methacrylamide) - HEMAM; and (N-(1-hydroxybutan-2-yl) methacrylamide) -2EM; were combined with bifunctional monomers containing the same polymerizing moieties as the monofunctional counterparts (HEMA-BDI; 2EMATE-BDI; HEMAM-BDI; and 2EM-BDI) at 50/50 M ratios. BHT was used as inhibitor (0.1 wt%) and the photoinitiators used were: CQ + EDMAB (0.2/0.8), BAPO (0.2), IVOCERIN (0.2), and DMPA (0.2), in wt%. The polymerization kinetics were monitored using Near-IR spectroscopy (∼6165 cm-1) in real-time while the specimens were photoactivated with a mercury arc lamp (Acticure 2; 320-500 nm, 300 mW/cm2) for 5 min, and maximum rate of polymerization (Rpmax, in %.s-̄1), degree of conversion at Rpmax (DC@Rpmax, in %), and the final degree of conversion (Final DC, in %) were calculated (n = 3). Initial viscosity was measured with an oscillating rheometer (n = 3). Data were analyzed using Two-way ANOVA for the polymerization kinetics and one-way ANOVA for the viscosity. Multiple comparisons were made using the Tukey's test (∝ = 0.05). RESULTS: There was statistically significant interaction between monomer and photoinitiator (p < 0.001). For the methacrylates groups, the highest Rpmax was observed for HEMA + DMPA and 2EMATE + BAPO. For methacrylamides groups, the highest Rpmax were observed for HEMAM and 2EM, both with DMPA. Final DC was higher for the methacrylate groups, in comparison with methacrylamide groups, independent of the photoinitiators. However, for the methacrylamide groups, the association with BAPO led to the lowest values of DC. In terms of DC@Rpmax, methacrylate-based systems showed significantly higher values than methacrylamide formulations. DMPA and Ivocerin led to higher values than CQ/EDMAB and BAPO in methacrylamide-based compounds. BAPO systems showed de lowest values for both HEMA and HEMAM formulations. For the viscosity (Pa.s), only 2EM had higher values (1.60 ± 0.15) in comparison with all monomers. In conclusion, polymerization kinetics was affected by the photoinitiators for both monomers. Viscosity was significantly increased with the use of secondary methacrylamide. SIGNIFICANCE: this work demonstrated the feasibility of using newly-synthesized methacrylamide monomers in conjunction with a series of initiator systems already used in commercial materials.


Assuntos
Cimentos Dentários , Metacrilatos , Acrilamidas , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Teste de Materiais , Fotoiniciadores Dentários , Polimerização
6.
Dent Mater ; 36(3): 343-352, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31924386

RESUMO

OBJECTIVE: The structure of the polymer phase of dental resin-based-composites is highly sensitive to photo-polymerisation variables. The objective of this study was to understand how different polymer structures, generated with different photo-polymerisation protocols, respond to thermal perturbation. METHODS: Experimental resins were prepared from a series of Bis-GMA/TEGDMA blends (40/60, 50/50 and 60/40 wt.%), with either Camphorquinone/DMAEMA or Lucirin TPO as the photo-initiator system. Resins were photo-polymerised, in a disc geometry, at either relatively 'high' (3000 mW cm-2 for 6 s) or 'low' (300 mW cm-2 for 60 s) irradiances ensuring matched radiant exposures (18 J cm-2). Specimens were heated, from 20-160 °C at a rate of 5 °C min-1, whilst simultaneous synchrotron X-ray scattering measurements were taken at 5 °C increments to determine changes in polymer chain segment extension and medium-range order as a function of temperature. For each unique resin composition (n = 3), differential scanning calorimetry was used to measure glass transition temperatures using the same heating protocol. A paired t-test was used to determine significant differences in the glass transition temperature between irradiance protocols and photo-initiator chemistry at ɑ = 0.05. RESULTS: Resins pre-polymerised through the use of TPO and or high irradiances demonstrated a reduced rate of chain extension indicative of lower thermal expansion and a larger decrease in relative order when heated below the glass transition temperature. Above the transition temperature, differences in the rate of chain extension were negligible, but slower converted systems showed greater relative order. There was no significant difference in the glass transition temperature between different photo-initiator systems or irradiance protocols. SIGNIFICANCE: The evolution of chain extension and medium-range order during heating is dependent on the initial polymer structure which is influenced by photo-polymerisation variables. Less ordered systems, generated at faster rates of reactive group conversion displayed reduced chain extension below the glass transition temperature and maintained lower order throughout heating.


Assuntos
Resinas Compostas , Resinas Sintéticas , Bis-Fenol A-Glicidil Metacrilato , Teste de Materiais , Polietilenoglicóis , Polimerização , Ácidos Polimetacrílicos , Resinas Vegetais , Temperatura
7.
J Prosthet Dent ; 123(2): 349-354, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31202550

RESUMO

STATEMENT OF PROBLEM: Three-dimensional printing has the potential for clinical applications, and additive manufacturing materials for dental use merit further investigation. PURPOSE: The purpose of this in vitro study was to evaluate the properties of materials formulated with ethoxylated bisphenol A-dimethacrylate (Bis-EMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) as 3D printing resins for ultraviolet digital light processing (UV-DLP) 3D printers and to characterize the mechanical and biological properties and accuracy of the printed objects. MATERIAL AND METHODS: Ten different light-polymerized resins were formulated using Bis-EMA, UDMA, and TEGDMA. Their viscosities were measured, and only 7 resins with viscosities lower than 1500 centipoise (cP) were selected for 3D printing and further material characterization. The light-polymerized resins were printed into representative shapes using a custom-made 3D printer equipped with a 405-nm UV-DLP projector as the light source. The printed specimens were subjected to biologic, mechanical, and accuracy tests, and the data were submitted to 1-way ANOVA and Tukey post hoc comparisons (α=.05). RESULTS: Photopolymerizable resins made of Bis-EMA, UDMA, and TEGDMA were successfully formulated for 3D printing to fabricate objects of various shapes and sizes. TEGDMA served as the diluent to reduce the viscosity and increase the degree of conversion, while UDMA and Bis-EMA provided strength as demonstrated by the mechanical testing. All the printed objects passed cytotoxicity testing. The flexural strengths of the printed specimens ranged between 60 MPa and 90 MPa; flexural modulus ranged between 1.7 GPa and 2.1 GPa; and surface hardness ranged between 14.5 HV and 24.6 HV. These represent similar mechanical properties to those of currently used clinical resin materials. In the accuracy test, the resin mixture composed of 80% Bis-EMA, 10% UDMA, and 10% TEGDMA had the highest accuracy, with a 0.051-mm deviation from the original design. CONCLUSIONS: Bis-EMA, UDMA, and TEGDMA are good candidates for the formulation of 3D printing resins for dental use. The printed objects demonstrated favorable biological and mechanical properties. Further, the accuracy of the printed specimens showed potential for clinical application.


Assuntos
Resinas Compostas , Ácidos Polimetacrílicos , Bis-Fenol A-Glicidil Metacrilato , Teste de Materiais , Metacrilatos , Polietilenoglicóis , Poliuretanos , Impressão Tridimensional
8.
Clin Oral Investig ; 24(1): 369-375, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31104114

RESUMO

PURPOSE: To determine the effect of aging methods on the fracture toughness of a conventional Bis-GMA-based resin composite (Filtek Supreme), an ormocer-based resin composite (Admira), and an experimental hydrophobic oxirane/acrylate interpenetrating network resin system (OASys)-based composite. METHODS: A 25 × 5 × 2.8-mm stainless-steel mold with 2.5 mm single-edge center notch, following ASTM standards [E399-90], was used to fabricate 135 specimens (n = 15) of the composite materials and randomly distributed into groups. For the baseline group, specimens were fabricated and then tested after 24-h storage in water. For the biofilm challenge, specimens were randomly placed in a six-well tissue culture plate and kept at 37 °C with bacterial growth media (Brain Heart Infusion (BHI); Streptococcus mutans) changed daily for 15 days. For the water storage challenge, specimens were kept in 5 ml of deionized distilled autoclaved water for 30 days at 37 °C. µCT evaluation by scanning the specimens was performed before and after the proposed challenge. Fracture toughness (KIc) testing was carried out following the challenges. RESULTS: µCT surface area and volume analyses showed no significant changes regardless of the materials tested or the challenge. Filtek and Admira fracture toughness was significantly lower after the biofilm and water storage challenges. OASys mean fracture toughness values after water aging were significantly higher than that of baseline. Toughness values for OASys composites after biofilm aging were not statistically different when compared to either water or baseline values. CONCLUSION: The fracture toughness of Bis-GMA and ormocer-based dental resin composites significantly decreased under water and bacterial biofilm assault. However, such degradation in fracture toughness was not visible in OASys-based composites. CLINICAL SIGNIFICANCE: Current commercial dental composites are affected by the oral environment, which might contribute to the long-term performance of these materials.


Assuntos
Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Óxido de Etileno , Cerâmicas Modificadas Organicamente , Teste de Materiais , Propriedades de Superfície
9.
Dent Mater ; 36(1): e15-e26, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31791735

RESUMO

OBJECTIVE: The object is to find an easy but efficient way to illustrate the in-situ dispersion of nano-scaled one-dimensional fillers in composite resins, and to correlate their dispersion status with the properties of composite resins. METHODS: Fluorescent europium-doped hydroxyapatite nanowires (HANW:Eu) were synthesized via the hydrothermal method. The HANW:Eu was mixed into Bis-GMA/TEGDMA (60/40, w/w) at different contents (1-5wt.%), and different processing methods (kneading, grinding, stirring) were tested to achieve good dispersion of HANW:Eu with the aid of fluorescent imaging system. Then, the mixtures of HANW:Eu and barium glass powder (BaGP) were kneaded into resin at a fixed content (70wt.%) while at different mixing ratios. In addition to the 3D fluorescent imaging, characterizations were carried out on mechanical properties, fractured surface, wear resistance and polymerization shrinkage, to correlate the composite properties of with the dispersion status of the incorporated HANW:Eu. RESULTS: By doping calcium with 5mol.% of europium, the obtained HANW:Eu displayed strong fluorescence, which made the illustration of its in-situ dispersion status within composites being possible. And this helped to judge that kneading was more efficient to homogeneously disperse HANW:Eu than grinding and stirring. However, it was illustrated vividly that HANW:Eu aggregated severely when it was co-incorporated with BaGP into composites at the total content of 70wt.%, which had not been previously revealed by other microscope observations. In comparison with composites containing 70wt.% of BaGP, improvements in the mechanical properties of resulting composites were identified for the cases containing 3wt.% of HANW and 67wt.% of BaGP, however, their wear volume loss and the polymerization shrinkage did not decrease as expected due to the HANW aggregations. SIGNIFICANCE: The fluorescent filler prepared in this study provides a feasible strategy to illustrate the in-situ dispersion status of inorganic fillers, which provides guidance for the processing of composite resins.


Assuntos
Durapatita , Nanofios , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Európio , Teste de Materiais , Polietilenoglicóis , Ácidos Polimetacrílicos , Propriedades de Superfície
10.
Dent Mater ; 36(1): 157-166, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31791739

RESUMO

OBJECTIVE: Although bisphenol A-glycidyl methacrylate (Bis-GMA)-based dental materials are widely used in dentistry, Estrogenicity from released bisphenol A remains a concern due to possibility of adversely affecting the growth of children and homeostasis of adults. Here, a new family of isosorbide-derived biomonomers were synthesized and experimentally utilized as a matrix of dental sealants to provide physico-mechanical and biological properties comparable to those of a conventional Bis-GMA-based material but without the the potential estrogenicity. METHODS: After synthesis of isosorbide-derived biomonomers (ISDB) by light polymerization, an experimental dental sealant with different silica filler concentrations (0-15wt%) was characterized and compared to a commercially available Bis-GMA-based sealant. Cytotoxicity and estrogenicity assays were conducted with human oral keratinocytes and estrogen-sensitive MCF-7 cells, respectively. RESULTS: ISDB-based dental sealants exhibited typical initially smooth surfaces with depth of cure, Vickers hardness, compressive strength/modulus, water resorption/solubility, and flowability comparable to those of the commercial sealant and met the ISO standard for dental sealants and polymer-based restorative materials. Indirect cytotoxicity tests using an extract showed comparable viability among experimental ISDB-based materials and a commercial Bis-GMA-incorporated control. DNA synthesis in MCF-7 cells (a marker of estrogenicity) and the release of bisphenol A under enzymatic incubation were not detected in ISDB-based materials. SIGNIFICANCE: In conclusion, the comparable physico-mechanical properties of ISDB-based materials with their cytocompatibility and lack of estrogenicity suggest the potential usefulness of ISDBs as a newly developed and safe biomaterial.


Assuntos
Polietilenoglicóis , Ácidos Polimetacrílicos , Adulto , Biopolímeros , Bis-Fenol A-Glicidil Metacrilato , Criança , Resinas Compostas , Humanos , Teste de Materiais , Polimerização
11.
Dent Mater ; 36(2): 187-196, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31791740

RESUMO

OBJECTIVE: The aim of our study is to develop amine-free photoinitiating systems (PISs) for the polymerization of representative dental methacrylate resins under blue light irradiation. PISs based on camphorquinone (CQ)/sulfinate and CQ/sulfonate, eventually in combination with an iodonium salt, are proposed and compared to the well-established CQ/amine system. The polymerization performances of thick (1.4 mm) samples of different methacrylate blends upon exposure to a commercial blue LED centered at 477 nm under air are described. Finally, the performances of the new developed PISs are evaluated for dental composites application. METHODS: FTIR is used to monitor the photopolymerization profiles. ESR spectroscopy and electrochemical experiments are used to identify the radicals generated. Mechanical properties measurements and color stability measurements are carried out to determine the key properties of the dental composites prepared. RESULTS AND SIGNIFICIANCE: The performances of the new proposed PISs for the photopolymerization of thick (1.4 mm) samples of methacrylate upon exposure to a blue dental LED under air are excellent. Similar or better performances and bleaching properties are obtained with the new proposed amine-free systems compared to those reached with the CQ/amine reference system. Dental composites with excellent mechanical properties and exceptional color stability are obtained. The involved chemical mechanisms for the initiation step were also established.


Assuntos
Resinas Compostas , Metacrilatos , Aminas , Bis-Fenol A-Glicidil Metacrilato , Cânfora/análogos & derivados , Teste de Materiais , Polimerização
12.
Dent Mater ; 36(2): 221-228, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31791741

RESUMO

OBJECTIVE: The aim of this study was to incorporate sol-gel-derived bioactive glass as filler into experimental adhesive resins and evaluate the influence of glass composition on the physicochemical and biological properties of the developed adhesives. MATERIALS AND METHODS: Sol-gel particles were produced with or without the addition of niobium (BAGNb or BAG, respectively). The produced particles were incorporated (2wt%) into experimental adhesive resins formulated with 66wt% bisphenol A-glycidyl methacrylate and 33wt% hydroxyethyl methacrylate. Ethyl dimethyl-4-aminobenzoate and camphorquinone were used as photoinitiator system. Two experimental groups were produced: ABAGNb and ABAG. The adhesive without particles was used as control (ACG). The materials were tested for their degree of conversion, softening in solvent, and cytotoxicity. The mineral deposition was analyzed by Raman spectroscopy. Flexural strength and immediate and 1-year microtensile bond strength were evaluated. RESULTS: No statistical difference was found in degree of conversion. ABAGNb showed reduced softening and higher mineral deposition than ACG and ABAG after 28 days. ABAG and ABAGNb resulted in higher cell viability and lower flexural strength when compared to ACG. After 1-year, ABAGNb and ABAG presented statistically significant lower µTBS values. SIGNIFICANCE: Sol-gel-derived bioactive glasses promoted increased mineral deposition and cell viability for experimental adhesives with increased phosphate content and longitudinal µTBS values for the ABAGNb group. These results suggest the potential of the studied particles to be applied as bioactive fillers for dental adhesives. Reductions in longitudinal µTBS and flexural strength, however, were observed for both glasses compositions and must be considered.


Assuntos
Colagem Dentária , Nióbio , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Cimentos Dentários , Adesivos Dentinários , Vidro , Teste de Materiais , Metacrilatos , Resistência à Tração
13.
Dent Mater ; 36(2): e29-e37, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31831181

RESUMO

OBJECTIVE: The aim of this study was to evaluate the effect of different photoinitiator systems on the cell viability and physico-chemical properties of an experimental adhesive resin of a two-step self-etch adhesive system. METHODS: Eight photoinitiators and coinitiators were evaluated, camphorquinone (CQ); ethyl-dimethylamino benzoate (EDAB); diphenyliodonium hexafluorophosphate (DPIHFP); 1,3-benzodioxole (BDO); piperonyl alcohol (AP); 1,3-diethyl-2-thiobarbituric acid (TBA); bisphenyl phosphinic oxide (BAPO); and diphenyl phosphinic oxide (TPO). Seven experimental adhesive resins (Bis-GMA:TEGDMA - 1:1 by wt%) were formulated by varying the initiation systems: RCQ+EDAB (control), RCQ+EDAB+DPHFP, RCQ+BDO, RCQ+AP, RCQ+TBA, RBAPO and RTPO. The cell viability of the different photoinitiators in their isolated form and after being incorporated into the adhesive resins was evaluated using the MTT assay. The degree of conversion within the hybrid layer (DC in situ) was evaluated by micro-Raman spectroscopy; the polymerization kinetics, by FTIR spectroscopy. The water sorption (Wsp) and solubility (Wsl) were calculated by using percentage of gain and loss of mass. Data were analyzed using One-way ANOVA and Kruskal-Wallis tests (α=0.05). RESULTS: When evaluated in their isolated form, the DPIHFP was considered cytotoxic in all concentrations evaluated. When incorporated into and adhesive resin, RCQ+TBA presented higher cell viability values than control and the highest values of DC in situ (p<0.05). Additionally, the use of CQ+TBA showed a higher cell viability when compared with the conventional CQ+EDAB system. SIGNIFICANCE: The pair CQ+TBA could be potentially useful in the development of materials with improved biocompatibility.


Assuntos
Resinas Compostas , Cimentos Dentários , Bis-Fenol A-Glicidil Metacrilato , Teste de Materiais , Polimerização , Solubilidade
14.
J Prosthet Dent ; 123(2): 339-348, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31079889

RESUMO

STATEMENT OF PROBLEM: Monomer leaching from restorations may affect the oral mucosa and general health; however, information on monomer leaching from chairside computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials is lacking. PURPOSE: The purpose of this in vitro study was to investigate the leaching of monomers from newly introduced resin-modified ceramics and composite resin CAD-CAM blocks that were immersed in water and ethanol for short-term and long-term incubation periods. MATERIAL AND METHODS: Ten square-shaped specimens of 5 newly introduced CAD-CAM blocks were suspended by means of a silk thread in distilled water and in 75% ethanol. After 1 day, 7 days, 30 days, and 60 days, the eluates bisphenol A (BPA), urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEGDMA), N, N-dimethylacrylamide (DMA), bisphenol A-glycidyl dimethacrylate (Bis-GMA), and bisphenol A ethoxylate dimethacrylate (Bis-EMA) were analyzed by means of high-performance liquid chromatography (HPLC). Additional specimens of each material, before and after immersion in the solutions, were investigated by scanning electron microscopy, and elemental analysis was performed by energy-dispersive X-ray spectrometry. RESULTS: TEGDMA and UDMA were the main monomers eluted from all the materials tested. A pattern of declining release was detected for all the monomers. Bisphenol-A was not released by any of the investigated ceramic-composite or composite resin blocks either in water or ethanol. CONCLUSIONS: CAD-CAM blocks release less monomer when they are immersed in aqueous solutions in the short-term and long-term periods than conventional resin composite materials. The amount of monomer release declined until no monomer could be detected.


Assuntos
Cerâmica , Resinas Compostas , Bis-Fenol A-Glicidil Metacrilato , Desenho Assistido por Computador , Materiais Dentários , Teste de Materiais , Polietilenoglicóis , Ácidos Polimetacrílicos
15.
Support Care Cancer ; 28(1): 239-247, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31020438

RESUMO

OBJECTIVES: To evaluate the in vitro effects of radiotherapy (RT) on the morphological surface of the enamel and dentin and to determine the best adhesive system and most appropriate time to restore teeth in head and neck cancer patients. METHODS: Sixty third molars were cut into 120 enamel fragments and 120 dentin fragments and divided into four groups (n = 30): G1 (control): nonirradiated, only restorative procedure; G2: restorative procedure immediately before RT; G3: restorative procedure immediately after RT; and G4: restorative procedure 6 months after RT. Each group was divided into two subgroups: Adper™ Single Bond 2 (SB) and Clearfill SE Bond (CL) based on the material used. After RT and restorative procedures, the specimens were subjected to confocal microscopy and shear bond strength test. Data were analyzed using a two-way ANOVA followed by Tukey's test at a significance level of 5%. RESULTS: Morphological changes were observed in both substrates after a cumulative dose of 40 Gy, and after 60 Gy, the changes were more evident in both substrates. CL had the highest strength values in both substrates (p < 0.05), and G2 had the lowest strength values for the enamel and dentin (p < 0.05). CONCLUSIONS: Based on the in vitro study results, we can conclude that RT substantially changes the morphological surface of enamel and dentin and impairs the bond strength. The Clearfill system yielded better results than Adper Single Bond 2, and restoring teeth before RT resulted in the worst results in both substrates.


Assuntos
Adesivos/efeitos da radiação , Esmalte Dentário/efeitos da radiação , Adesivos Dentinários/efeitos da radiação , Dentina/efeitos da radiação , Neoplasias de Cabeça e Pescoço/radioterapia , Bis-Fenol A-Glicidil Metacrilato/efeitos da radiação , Resinas Compostas/efeitos da radiação , Colagem Dentária , Dentição Permanente , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Teste de Materiais , Dente Molar/efeitos da radiação , Doses de Radiação , Distribuição Aleatória , Cimentos de Resina/efeitos da radiação , Resistência ao Cisalhamento/efeitos da radiação , Fraturas dos Dentes/etiologia , Fraturas dos Dentes/patologia
16.
Dent Mater ; 36(2): 310-319, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31866065

RESUMO

OBJECTIVE: To provide conditions for the validity of the exposure reciprocity law as it pertains to the photopolymerization of dimethacrylate-based dental composites. METHODS: Composites made from different mass ratios of resin blends (Bis-GMA/TEGDMA and UDMA/TEGDMA) and silanized micro-sized glass fillers were used. All the composites used camphorquinone and ethyl 4-dimethylaminobenzoate as the photo initiator system. A cantilever beam-based instrument (NIST SRI 6005) coupled with NIR spectroscopy and a microprobe thermocouple was used to simultaneously measure the degree of conversion (DC), the polymerization stress (PS) due to the shrinkage, and the temperature change (TC) in real time during the photocuring process. The instrument has an integrated LED light curing unit providing irradiances ranging from 0.01W/cm2 to 4W/cm2 at a peak wavelength of 460nm (blue light). Vickers hardness of the composites was also measured. RESULTS: For every dental composite there exists a minimum radiant exposure required for an adequate polymerization (i.e., insignificant increase in polymerization with any further increase in the radiant exposure). This minimum predominantly depends on the resin viscosity of composite and can be predicted using an empirical equation established based on the test results. If the radiant exposure is above this minimum, the exposure reciprocity law is valid with respect to DC for high-fill composites (filler contents >50% by mass) while invalid for low-fill composites (that are clinically irrelevant). SIGNIFICANCE: The study promotes better understanding on the applicability of the exposure reciprocity law for dental composites. It also provides a guidance for altering the radiant exposure, with the clinically available curing light unit, needed to adequately cure the dental composite in question.


Assuntos
Resinas Compostas , Materiais Dentários , Bis-Fenol A-Glicidil Metacrilato , Teste de Materiais , Polimerização , Viscosidade
17.
J Contemp Dent Pract ; 20(9): 1077-1081, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31797833

RESUMO

AIM: The aim of this study was to compare different dentin treatments and adhesive systems on shear bond strength (SBS) of composite to superficial dentin. MATERIALS AND METHODS: In this in vitro experimental study, 60 extracted human upper premolars were cut 0.5 mm deep under occlusal DEJ and were randomly divided into six groups (n = 10) based on the method of dentin treatment and adhesive system: (A) two steps self-etch adhesive system (Clearfil SE bond) and (B) two steps of total etch bonding system (Adper single bond 2). (C) 10% papain + Clearfil SE bond. (D) 10% papain + Adper single bond 2. (E) 6% bromelain + Clearfil SE bond. (F) 6% bromelain + Adper single bond 2. Then, a plastic mold was placed on dentin and filled with resin composite. Shear bond strength (MPa) was tested by a universal testing machine (Zwick/Roell Z020, Germany), and the data were statistically analyzed by two-way ANOVA and Tukey's test (p < 0.05) and were applied for mean comparison. RESULTS: A significant difference was detected in the SBS evaluation between the applied adhesive systems (p = 0.0007). The SBS was also significantly affected by the interaction of treatment and etching techniques (p = 0.028). The group with 10% papain as a deproteinizing agent before the self-etching adhesive system showed the highest SBS (p = 0.029). There were no significant differences considering the specimens exposed to papain before the total etch adhesive system (p = 0.13), and the specimens were exposed to bromelain enzyme before self-etch and total etch adhesive systems (p = 0.25, p = 0.84, respectively). CONCLUSION: Papain enzyme treatment with the self-etch adhesive system increased the SBS value. Additionally, the application of bromelain enzyme as dentin treatment before two adhesive systems and papain before total etch adhesive system had no effect on the SBS of composite to superficial dentin. CLINICAL SIGNIFICANCE: Application of adhesive systems and dentin treatment can influence the bond strength.


Assuntos
Colagem Dentária , Papaína , Condicionamento Ácido do Dente , Bis-Fenol A-Glicidil Metacrilato , Bromelaínas , Resinas Compostas , Análise do Estresse Dentário , Dentina , Adesivos Dentinários , Alemanha , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento
18.
J Appl Oral Sci ; 27: e20180678, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596369

RESUMO

OBJECTIVES: Bulk-fill restorative materials such as bulk-fill composite resins and high viscous glass ionomer cements have become very popular materials in operative dentistry because their application is easy and time-saving. The aim of this clinical study was to evaluate the clinical performance of a highly viscous reinforced glass ionomer material, a bulk-fill composite resin and a micro hybrid composite resin in Class II restorations. METHODOLOGY: In total, 109 Class II restorations were performed in 54 patients using three different restorative materials: Charisma Smart Composite (CSC); Filtek Bulk Fill Posterior Restorative (FBF); Equia Forte Fil (EF). Single Bond Universal adhesive (3M ESPE, Germany) was used with composite resin restorations. The restorations were evaluated using modified USPHS criteria in terms of retention, color match, marginal discoloration, anatomic form, contact point, marginal adaptation, secondary caries, postoperative sensitivity and surface texture. The data were analyzed using Chi-Square, Fischer's and McNemar's tests. RESULTS: At the end of one year, 103 restorations were followed up. No changes were observed during the first 6 months. At the end of one year, there were small changes in composite restorations (FBF and CSC) but no statistically significant difference was observed between the clinical performances of these materials for all criteria (p>0.05). However, there was a statistically significant difference between EF, FBF and CSC groups in all parameters except marginal discoloration, secondary caries and postoperative sensitivity in one-year evaluation (p<0.05). CONCLUSION: Bulk-fill composite resins and conventional composite resins showed more successful clinical performance than highly viscous reinforced glass ionomers in Class II cavities.


Assuntos
Resinas Compostas/uso terapêutico , Restauração Dentária Permanente/métodos , Cimentos de Ionômeros de Vidro/uso terapêutico , Adulto , Bis-Fenol A-Glicidil Metacrilato/uso terapêutico , Cárie Dentária/terapia , Adaptação Marginal Dentária , Feminino , Humanos , Masculino , Estudos Prospectivos , Reprodutibilidade dos Testes , Distribuição por Sexo , Resultado do Tratamento , Adulto Jovem
19.
Dent Mater J ; 38(6): 1019-1025, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31582597

RESUMO

The goal of this study was to examine the effect of thermal cycling on the amount of monomer released from bulk fill composites. Five bulk fill composite resins were used in the study. Extraction solutions were obtained at the end of the time/thermal cycle periods: 0-1 day/0-1,500, 1-3 days/1,500-4,500 and 3-7 days/4,500-10,000. The monomers in the extractions samples taken at each time point were measured on an HPLC instrument. The obtained data were analyzed by repeated measures of variance analysis and tukey multiple comparison tests (p<0.05). The thermocycling increased the amount of monomer released from all composites at 0-1 day (p<0.05). At 0-1 and 1-3 days, Venus Bulk Fill and Filtek Bulk Fill composite resins were more affected. Polymer networks with high molecular weight monomers such as Bis-GMA and UDMA can be less affected by thermal changes compared to polymers with low molecular weight monomers.


Assuntos
Resinas Compostas , Polímeros , Bis-Fenol A-Glicidil Metacrilato , Cromatografia Líquida de Alta Pressão , Teste de Materiais
20.
Eur J Paediatr Dent ; 20(3): 224-232, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31489823

RESUMO

AIM: Recently, the application of restorative materials containing metacrilate monomers in the conservative and paediatric dentistry has focused on the possible negative effects due to the use of these composites. In particular the release of monomers from reconstructions as a result of an insufficient polymerisation, can spread along the mucosal and dental tissues with potential immunological ed cytotoxic effects. Regarding to the importance of this issue, the aim of this study is to provide a descriptive review of the literature on potential local and systemic interactions of metacrylic and acrylic monomers with the immune system, both in vitro and in vivo. RESULTS: The most highly used monomers in composite materials applied in conservative dentistry include: 2-hydroessietil- methacrylate (HEMA), triethylene glycol-dimethacrylate (TEGDMA), bisphenol A glycidyl-methacrylate (BisGMA) and urethane- dimethacrylate (UDMA). Different investigations have been performed for better understanding of the potential side effects of metacrylic monomers on immune system cells. Different factors such as cell population, exposure time and parameters more strictly connected to these materials, such as molecular weight, chemical composition and mechanical characteristics, seem to be directly involved in these reactions.


Assuntos
Resinas Compostas , Metacrilatos , Bis-Fenol A-Glicidil Metacrilato , Criança , Materiais Dentários , Humanos , Teste de Materiais
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