RESUMO
The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.
Assuntos
Compostos de Bifenilo/química , Dentina/efeitos dos fármacos , Cura Luminosa de Adesivos Dentários/métodos , Oniocompostos/química , Fotoiniciadores Dentários/química , Técnica para Retentor Intrarradicular , Cimentos de Resina/química , Ápice Dentário/efeitos dos fármacos , Análise de Variância , Compostos de Bifenilo/efeitos da radiação , Lâmpadas de Polimerização Dentária , Dentina/efeitos da radiação , Vidro/química , Vidro/efeitos da radiação , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Oniocompostos/efeitos da radiação , Fotoiniciadores Dentários/efeitos da radiação , Polimerização , Cimentos de Resina/efeitos da radiação , Fatores de Tempo , Ápice Dentário/efeitos da radiação , Fraturas dos Dentes , para-Aminobenzoatos/química , para-Aminobenzoatos/efeitos da radiaçãoRESUMO
STATEMENT OF PROBLEM: The use of photosensitizers in photodynamic therapy promotes intraradicular microbial reduction during nonsurgical endodontic therapy. However, studies are lacking on the consequences of the application of these agents on the mechanical properties of intraradicular dentin and on the bond strength of glass-fiber posts. PURPOSE: The purpose of this in vitro study was to evaluate the influence of photodynamic therapy on the bond strength of glass-fiber posts using a push-out test and, additionally, to measure the Martens hardness (MH) and elastic indentation modulus (Eit) of intraradicular dentin when different photosensitizers are used. MATERIAL AND METHODS: Eighty bovine teeth were used to simulate experimental endodontic treatments. Biomechanical instrumentation was performed for all root canals, and the teeth were distributed into 5 groups: control-deionized water; methylene blue 50 mg/L + red laser; methylene blue 100 mg/L + red laser; curcumin 500 mg/L + blue LED; and curcumin 1000 mg/L + blue LED. The MH and Eit of intraradicular dentin were measured using an ultramicrohardness tester under a load of 3 mN (n=8). The push-out bond strength of glass-fiber posts to dentin was measured using a universal testing machine (n=8). Mechanical properties and bond strength data were subjected to the Kruskal-Wallis test, ANOVA, and Fisher least significant difference test (α=.05). Images of representative specimens were obtained using a scanning electron microscope. RESULTS: The MH, Eit, and bond strength of intraradicular dentin were influenced by the photosensitizer used. In general, curcumin promoted lower mechanical properties values but higher bond strength values. CONCLUSIONS: Photosensitizers influenced the mechanical properties of intraradicular dentin and the bond strength of glass-fiber posts, and methylene blue at 50 mg/L had no marked effect on the mechanical properties of the dentin or the bond strength values.
Assuntos
Colagem Dentária , Dentina/efeitos da radiação , Vidro/efeitos da radiação , Fotoquimioterapia/métodos , Técnica para Retentor Intrarradicular , Resistência à Tração/efeitos da radiação , Análise de Variância , Animais , Bismuto , Hidróxido de Cálcio , Bovinos , Resinas Compostas , Colagem Dentária/métodos , Materiais Dentários/química , Materiais Dentários/efeitos da radiação , Cavidade Pulpar , Dentina/ultraestrutura , Adesivos Dentinários/química , Adesivos Dentinários/efeitos da radiação , Teste de Materiais , Cimentos de Resina/química , Estresse Mecânico , Dente não VitalRESUMO
CONTEXT: Light transmission (LT) into deeper areas of the dentin root is limited. AIM: The aim of this study is to perform a quantitative investigation of the radial transmission of light (LT) through different fiber posts and its influence on the Knoop hardness number (KHN) and bond strength (BS) of a dual-cure self-adhesive resin cement at 3 different depths. MATERIALS AND METHODS: Four types of fiber posts (2 translucent and 2 conventional) were used. LT and KHN analyses were performed in a specially designed matrix, which allowed measurements at 3 different depths. LT was measured using a volt-ampere meter while KHN tests were performed in a microhardness tester. For BS analysis, endodontically treated bovine roots were divided into 4 groups, each group receiving one type of post. After cementation, cross sections of the root were tested for resistance to displacement using a universal testing machine. STATISTICAL ANALYSIS USED:: Statistical analysis was performed by using this ANOVA and Tukey's test. RESULTS: For LT, translucent posts showed significantly higher values at all depths compared to the conventional ones. For all posts, LT decreased at the deeper depths. The KHN results showed no statistical differences among the different posts, regardless of depth. For BS, a translucent post showed the highest values, and comparative analyses between the different depths of posts also showed statistically significant differences while comparisons among the different depths of the same post showed no differences. CONCLUSIONS: LT depended on the type of post and on depth. The type of post did not significantly influence the cement KHN. A translucent post showed higher BS in pooled data.
Assuntos
Resinas Compostas/uso terapêutico , Colagem Dentária/métodos , Técnica para Retentor Intrarradicular , Análise do Estresse Dentário , Vidro/química , Vidro/efeitos da radiação , Dureza , Humanos , Luz , Técnica para Retentor Intrarradicular/instrumentaçãoRESUMO
Abstract The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.
Assuntos
Oniocompostos/química , Compostos de Bifenilo/química , Técnica para Retentor Intrarradicular , Ápice Dentário/efeitos dos fármacos , Cimentos de Resina/química , Dentina/efeitos dos fármacos , Cura Luminosa de Adesivos Dentários/métodos , Fotoiniciadores Dentários/química , Oniocompostos/efeitos da radiação , Fatores de Tempo , Fraturas dos Dentes , Compostos de Bifenilo/efeitos da radiação , Teste de Materiais , Análise de Variância , Ápice Dentário/efeitos da radiação , Cimentos de Resina/efeitos da radiação , Dentina/efeitos da radiação , Lâmpadas de Polimerização Dentária , Fotoiniciadores Dentários/efeitos da radiação , Polimerização , para-Aminobenzoatos/efeitos da radiação , para-Aminobenzoatos/química , Vidro/efeitos da radiação , Vidro/química , Metacrilatos/efeitos da radiação , Metacrilatos/químicaRESUMO
OBJECTIVE: The aim of this study was to evaluate the influence of laser irradiation on flexural strength, elastic modulus, and surface roughness and morphology of glass fiber posts (GFPs). BACKGROUND DATA: Laser treatment of GFPs has been introduced to improve its adhesion properties. MATERIALS AND METHODS: A total of 40 GFPs were divided into 4 groups according to the irradiation protocol: GC-no irradiation, GYAG-irradiation with erbium:yttrium-aluminum-garnet [Er:YAG], GCR-irradiation with erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG), and GDI-irradiation with diode laser. The GFP roughness and morphology were evaluated through laser confocal microscopy before and after surface treatment. Three-point bending flexural test measured flexural strength and elastic modulus. Data about elastic modulus and flexural strength were subjected to one-way ANOVA and Bonferroni test (p < 0.05). The effect of roughness was evaluated using the linear mixed effects model and Bonferroni test (p < 0.05). RESULTS: Laser treatment changed surface roughness in the groups GCR (p = 0.000) and GDI (p = 0.007). The mean flexural strength in GYAG (995.22 MPa) was similar to that in GC (980.48 MPa) (p = 1.000) but different from that in GCR (746.83 MPa) and that in GDI (691.34 MPa) (p = 0.000). No difference was found between the groups GCR and GDI (p = 0.86). For elastic modulus: GYAG (24.47 GPa) was similar to GC (25.92 GPa) (p = 1.000) but different from GCR (19.88 GPa) (p = 0.002) and GDI (17.20 GPa) (p = 0.000). CONCLUSIONS: The different types of lasers, especially Er,Cr:YSGG and 980 ηm diode, influenced the mechanical properties of GFPs.
Assuntos
Vidro/efeitos da radiação , Lasers , Técnica para Retentor Intrarradicular , Lasers de Estado Sólido , Teste de Materiais , Propriedades de SuperfícieRESUMO
OBJECTIVES: The purpose of this study was to evaluate the flexural strength and Vickers hardness of a microwave energy heat-cured acrylic resin by adding different concentrations of silane surface-treated nanoparticle silica. METHODS: Acrylic resin specimens with dimensions of 65 × 10 × 2.5 mm were formed and divided into five experimental groups (n = 10) according to the silica concentration added to the acrylic resin mass (weight %) prior to polymerisation : G1, without silica; G2, 0.1% silica; G3, 0.5% silica; G4, 1.0% silica; and G5, 5.0% silica. The specimens were submitted to a three-point flexural strength test and to the Vickers hardness test (HVN). The data obtained were statistically analysed by anova and the Tukey test (α = 0.05). RESULTS: Regarding flexural strength, G5 differed from the other experimental groups (G1, G2, G3 and G4) presenting the lowest mean, while G4 presented a significantly higher mean, with the exception of group G3. Regarding Vickers hardness, a decrease in values was observed, in which G1 presented the highest hardness compared with the other experimental groups. CONCLUSION: Incorporating surface-treated silica resulted in direct benefits in the flexural strength of the acrylic resin activated by microwave energy; however, similar results were not achieved for hardness.
Assuntos
Resinas Acrílicas/química , Materiais Dentários/química , Micro-Ondas , Silanos/química , Dióxido de Silício/química , Resinas Acrílicas/efeitos da radiação , Materiais Dentários/efeitos da radiação , Análise do Estresse Dentário/instrumentação , Vidro/química , Vidro/efeitos da radiação , Dureza , Temperatura Alta , Humanos , Teste de Materiais , Nanopartículas/química , Nanopartículas/efeitos da radiação , Maleabilidade , Polimerização , Silanos/efeitos da radiação , Dióxido de Silício/efeitos da radiação , Estresse Mecânico , Propriedades de SuperfícieRESUMO
OBJECTIVE: This study evaluated the effect of post-polymerisation treatments on the glass transition temperature (T(g)) of five hard chairside reline materials (Duraliner II-D, Kooliner-K, New Truliner-N, Ufi Gel hard-U and Tokuso Rebase Fast-T). MATERIALS AND METHODS: Specimens (10 x 10 x 1 mm) were made following the manufacturers' instructions and divided into three groups (n = 5). Control group specimens were left untreated. Specimens from the microwave group were irradiated with pre-determined power/time combinations, and specimens from the water-bath group were immersed in hot water at 55 degrees C for 10 min. Glass transition ( degrees C) was performed by differential scanning calorimetry. Data were analysed using anova, followed by post hoc Tukey's test (alpha = 0.05). RESULTS: Both post-polymerisation treatments promoted a significant (p < 0.05) increase in the T(g) of reline material K. Materials K, D and N showed the lowest T(g) (p < 0.05). No significant difference between T and U specimens was observed. CONCLUSION: Post-polymerisation treatments improved the glass transition of material Kooliner, with the effect being more pronounced for microwave irradiation.
Assuntos
Materiais Dentários/química , Reembasadores de Dentadura , Vidro/química , Resinas Acrílicas/química , Resinas Acrílicas/efeitos da radiação , Varredura Diferencial de Calorimetria , Materiais Dentários/efeitos da radiação , Reembasamento de Dentadura , Vidro/efeitos da radiação , Temperatura Alta , Humanos , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Micro-Ondas , Polimerização , Elastômeros de Silicone/química , Elastômeros de Silicone/efeitos da radiação , Fatores de Tempo , Temperatura de Transição , Água/químicaRESUMO
OBJECTIVE: This study evaluated the glass transition temperature (Tg) and degree of conversion (DC) of a light-cured (Fill Magic) versus a chemically cured (Concise) orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s). RESULTS: Fill Magic presented lower Tg than Concise (35-84 masculineC versus 135 masculineC), but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm(2) is necessary to reach adequate conversion level and obtain satisfactory adhesion.
Assuntos
Resinas Compostas/química , Vidro/química , Braquetes Ortodônticos , Cimentos de Resina/química , Temperatura de Transição , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária/classificação , Módulo de Elasticidade , Transferência de Energia , Fricção , Vidro/efeitos da radiação , Temperatura Alta , Humanos , Luz , Teste de Materiais , Polímeros/química , Cimentos de Resina/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral , Fatores de TempoRESUMO
OBJECTIVE: This study evaluated the glass transition temperature (Tg) and degree of conversion (DC) of a light-cured (Fill Magic) versus a chemically cured (Concise) orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s). RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC), but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.
Assuntos
Humanos , Resinas Compostas/química , Vidro/química , Braquetes Ortodônticos , Cimentos de Resina/química , Temperatura de Transição , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária/classificação , Módulo de Elasticidade , Transferência de Energia , Fricção , Vidro/efeitos da radiação , Temperatura Alta , Luz , Teste de Materiais , Polímeros/química , Cimentos de Resina/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral , Fatores de TempoRESUMO
This study evaluated the irradiance of curing units through core and veneered hot-pressed ceramics as well as the transmittance of these materials. Discs of 0.7, 1.4 and 2 mm in thickness of Empress (EMP) and Empress Esthetic (EST), and 0.8 (n=5) and 1.1 mm (n=5) thickness of Empress 2 (E2) were obtained. For E2, two of the 0.8-mm-thick discs were covered with dentin (1.2- and 1.4-mm-thick) and two with dentin + enamel (1.5-mm-thick). The 1.1-mm-thick specimens were submitted to the same veneering procedures. Specimens were evaluated by UV-Vis transmittance analysis and the percentage of transmittance was recorded. Irradiance through each specimen was evaluated with a quartz-tungsten-halogen (QTH), used in continuous or intermittent exposure modes, or a blue light-emitting diode (LED). Data were analyzed by Dunnett's test, ANOVA and Tukey's test at 5% significance level. Exposure through ceramic decreased the irradiance for all ceramics. Irradiance through EST was significantly higher than through EMP. For E2, reduction in irradiance depended on the core and/or veneer thickness. The QTH intermittent mode showed higher irradiance than the continuous mode, and both showed higher irradiance than LED. The ceramic significantly influenced irradiance and transmittance, which were found to decrease with the increase in thickness.