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Aim: This study evaluated the effect of a desensitizer agent (DES) during bleaching with 10% carbamide peroxide (CP) on enamel microshear bond strength (µSBS). Methods: Sixty bovine incisors were obtained and randomly distributed into groups (n=15): (C) Control: no desensitizing or bleaching, (DES) desensitizing gel application, (CP) bleaching with 10% CP and (CP/DES) bleaching with 10% CP combined with DES. Bleaching was performed for 6 h/day for 14 consecutive days. DES was applied for 8 h only on the 7th and 14th days of therapy. Specimens were stored in artificial saliva among the CP or DES applications and submitted to µSBS testing at three postrestoration times (n=5): 24 h, 7 days, and 14 days after bleaching using a universal testing machine. Failure modes were observed under a stereomicroscope. Data were analyzed by two-way ANOVA and Tukey's test (α=5%). Results: Immediately after bleaching (24 h), CP promoted lower µSBS than the C and DES groups (p<0.05) but with no differences from the CP/DES. µSBS increased in the DES, CP, and CP/DES groups (p<0.05) when bonding was performed for 7 or 14 days elapsed from bleaching. CP/DES exhibited the highest µSBS among the groups 14 days after bleaching (p<0.05). Cohesive failure in enamel was predominant in the CP groups, while adhesive failure was mostly observed for the other groups. Conclusion: The use of a desensitizer during at-home bleaching maintained the enamel immediate bond strength, and its application favored bonding when the restoration was delayed for 14 days
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Animais , Bovinos , Clareamento Dental , Esmalte Dentário , Resistência ao CisalhamentoRESUMO
PURPOSE: To evaluate the fracture resistance (FR), and push-out bond strengths (BS) of custom-made CAD/CAM post-and-cores manufactured with different esthetic materials. METHODS: 90 single-rooted extracted teeth were selected, endodontically treated and prepared to receive the posts. The specimens were randomly divided into three equal groups according to the material: hybrid ceramic Vita Enamic (HC); nano-ceramic resin composite Lava Ultimate (RC); and experimental epoxy-resin reinforced by glass-fiber (FG). The post-and-cores were manufactured using CAD/CAM and cemented using a self-adhesive resin cement (Rely X Unicem2). A subgroup of 30 specimens (n=10) was subjected to fatigue (1,000,000 cycles at 5 Hz) and then to the FR test. Another subgroup with 60 specimens was submitted to the BS test, with and without fatigue. Data were submitted to analysis of variance (FR - one-way ANOVA; BS - two-way ANOVA) and Tukey's test (α= 0.05). RESULTS: The FR values (mean±SD, in Newtons) were 414.5±83.9 (HC), 621.3±100.3 (RC), and 407.6±109.0 (FG), with RC showing significantly higher FR values (P< 0.05). For BS, there was no statistically significant difference among the materials, with and without fatigue (P> 0.05). The type of material used to obtain the CAD/CAM-customized post-and-cores had a significant effect on the FR, but not on the BS of the specimens. Fatigue did not influence the BS for the tested materials. CLINICAL SIGNIFICANCE: CAD/CAM custom-made esthetic post-and-cores showed good performance relative to fracture resistance and bond strength to root canal dentin walls. The CAD/CAM materials tested could be used as an alternative to restore wide flared root canals in esthetically compromised teeth.
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Desenho Assistido por Computador , Estética Dentária , Cimentos de Resina , Resinas Compostas , Análise do Estresse Dentário , Dentina , Vidro , Cimentos de Ionômeros de Vidro , Teste de Materiais , Técnica para Retentor Intrarradicular , Distribuição Aleatória , Estresse MecânicoRESUMO
OBJECTIVE: The objective of this study was to evaluate the diametral tensile strength (DTS) and Knoop hardness (KH) of direct (Filtek Z350-3M/ESPE and Charisma-Heraeus Kulzer) and indirect composites (Sinfony-3M/ESPE and Signum-Heraeus Kulzer) kept in storage for two periods of time, 24 hours and 10 months, in distilled water. METHODS: Twenty-five specimens of each material were prepared. DTS (n=10) was tested using a universal testing machine (Versat, model 2000) at a crosshead speed of 1.0 mm/min. KH (n=5) was measured using Knoop micro-hardness (HMV-2000; 50 gf for 15 s). All tests were performed 24 hours after polymerization and after 10 months of storage in distilled water at 37°C. The data were statistically analyzed using Kolmogorov-Smirnov, ANOVA and t-Student (P=.05). RESULTS: Filtek Z350, Sinfony, and Signum showed higher DTS values than Charisma after 24 hours. After storage, Sinfony and Signum showed higher DTS values because the storage did not influence the DTS values of the indirect composites. Filtek Z350 showed higher KH values after 24 hours and after storage than other composites; the storage influenced the KH of all composites except Sinfony. CONCLUSION: Storage for 10 months did not influence the properties of the indirect composite Sinfony. In general, the indirect composites showed higher DTS values than direct composites, especially after 10 months storage. The direct composite Filtek Z350 obtained the highest KH values regardless of storage.
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PURPOSE: To evaluate the implant-abutment interface area and the abutment screw loosening value when diamondlike carbon (DLC)-coated or titanium screws were used before and after cyclic loading. MATERIALS AND METHODS: Thirty-six implants were divided into four groups according to the type of connection (external hexagon [EH] or internal hexagon [IH]) and the type of abutment screw (with [EHD/IHD] or without [EHT/IHT] DLC coating). The implants were placed in epoxy resin-glass fiber composite, and crowns cast in a metal alloy were screwed to the implants. The implant-abutment interface was measured before (VG1) and after (VG2) cyclic loading. The removal torque values were recorded. RESULTS: In groups with titanium screws, there was an increase in the implant-abutment interface area from VG1 to VG2, whereas in groups with DLC-coated screws, the interface area was reduced (EHT = 4.49%, IHT = 24.32%, EHD = -1.05%, IHD = -9.95%). In the IHT group only, the implant-abutment interface area showed a statistically significant difference between VG1 and VG2. The Pearson correlation indicated no significant differences among the studied factors, where r = -0.11 for EHT, 0.14 for EHD, 0.07 for IHT, and 0.43 for IHD. CONCLUSIONS: The implant-abutment interface areas in groups with an EH connection were larger than those in groups with an IH connection, regardless of the type of screws used. The screw loosening values decreased in all groups after cyclic loading. No correlation between the implant-abutment interface area and the screw loosening value was seen.
Assuntos
Carbono , Dente Suporte , Implantes Dentários , Adaptação Marginal Dentária , Pinos Dentários , Titânio , Coroas , Planejamento de Prótese Dentária , Diamante , Resinas Epóxi , Humanos , TorqueRESUMO
Realizar o polimento das restaurações diretas em resina composta é importante para estabelecer uma superfície lisa e promover a saúde ao periodonto. O objetivo deste estudo é avaliar a influência de diferentes sistemas de polimento sobre a topografia de superfície de cinco resinas compostas: Master Fill, Vênus, Brilliant, Charisma Opal e Fitek Supreme. Confeccionaram-se 100 corpos de prova com uma matriz metálica cilíndrica de 5mm x 2mm (ISO 4872) distribuídos em cinco grupos teste, de acordo com o tipo polimento (n=20): escova de carbeto de silício (ECS), pasta diamantada (PD), pontas de borracha abrasiva (PB) e discos abrasivos (DA). Os valores de rugosidade (Ra) e as imagens obtidas com a Microscopia de Força Atômica (MFA) foram obtidos antes e após os métodos de polimento. Os resultados foram tabulados e analisados estatisticamente pelo teste de Tukey, com 5% de significância. Conclui-se que os procedimentos de polimento utilizados para as resinas testadas mostraram-se eficazes em reduzir a rugosidade da superfície, com valores variando entre 0,03µm e 0,11µm
Performing the polishing of composite resin direct restorations is important to provide a smooth surface and promote periodontal health. The aim of this study was to evaluate the influence of different polishing systems on surface topography of live composite resins: Master Fill, Venus, Brilliant, Charisma Opal and Filtek Z350. One hundred composite resin specimens were fabricated with a cylindrical metal matrix 5 x 2 mm (ISO 4872) distributed in 5 test groups, according to the type polishing (n:20): SCB silicon carbide brush, DP Diamond paste, TRA tips rubber abrasive and AD abrasive disc. The values of roughness (Ra) and the images taken by Atomic Force Microscopy (AFM) were obtained before and after polishing methods. The results were statistically analyzed by Tukey test at 5% significance level. It was conclude that the polishing procedure used for the resins tested were effective for reducing the surface roughness, with values ranging between 0.03 and 0,011 µm
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Resinas Compostas , Polimento Dentário , Estética DentáriaRESUMO
The purpose of this study was to evaluate the dimensional accuracy of different materials used in the confection of dies. Two stainless steel standard models were confected. One of the models, which was 2 mm larger than the other model, was used to provide a uniform relief for the two-step putty-wash impression technique. Thirty impressions were obtained using a polyvinyl siloxane impression material and randomly divided into three groups (n = 10) according to the type of casting material: type IV dental stone, commercially available epoxy resin (Tri-Epoxy), and industrial epoxy resin (Sikadur). After the setting/polymerization of the casting material, the dimensional stability was measured in terms of the height, diameter of the base and diameter of the top from the obtained dies and from the standard metal model using a profile projector. Results were analyzed by ANOVA and Dunnet test (α = 0.05). In the height values, no significant difference was observed between the groups, except for Sikadur casts, which showed lower mean values. The Tri-Epoxi group showed statistically lower mean base diameter values, compared with the other groups, and both epoxy resin groups showed statistically lower mean top diameter values, compared with that for the type IV dental stone group. We concluded that type IV gypsum and the commercially available epoxy resin showed similar behavior in most areas. The industrial epoxy resin did not show the same characteristics, although the diameter of the base obtained with it was similar to that obtained with type IV dental stone.
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The aim of the present study was to evaluate the influence of curing methods and composite volumes on the marginal and internal adaptation of composite restoratives. Two cavities with different volumes (Lower volume: 12.6 mm(3); Higher volume: 24.5 mm(3)) were prepared on the buccal surface of 60 bovine teeth and restored using Filtek Z250 in bulk filling. For each cavity, specimens were randomly assigned into three groups according to the curing method (n=10): 1) continuous light (CL: 27 seconds at 600 mW/cm(2)); 2) soft-start (SS: 10 seconds at 150 mW/cm(2)+24 seconds at 600 mW/cm(2)); and 3) pulse delay (PD: five seconds at 150 mW/cm(2)+three minutes with no light+25 seconds at 600 mW/cm(2)). The radiant exposure for all groups was 16 J/cm(2). Marginal adaptation was measured with the dye staining gap procedure, using Caries Detector. Outer margins were stained for five seconds and the gap percentage was determined using digital images on a computer measurement program (Image Tool). Then, specimens were sectioned in slices and stained for five seconds, and the internal gaps were measured using the same method. Data were submitted to two-way analysis of variance and Tukey test (p<0.05). Composite volume had a significant influence on superficial and internal gap formation, depending on the curing method. For CL groups, restorations with higher volume showed higher marginal gap incidence than did the lower volume restorations. Additionally, the effect of the curing method depended on the volume. Regarding marginal adaptation, SS resulted in a significant reduction of gap formation, when compared to CL, for higher volume restorations. For lower volume restorations, there was no difference among the curing methods. For internal adaptation, the modulated curing methods SS and PD promoted a significant reduction of gap formation, when compared to CL, only for the lower volume restoration. Therefore, in similar conditions of the cavity configuration, the higher the volume of composite, the greater the gap formation. In addition, modulated curing methods (SS and PD) can improve the interfacial quality of composite restorations through the reduction of internal gaps in lower volume composite restoratives.
Assuntos
Resinas Compostas/química , Adaptação Marginal Dentária , Materiais Dentários/química , Restauração Dentária Permanente , Condicionamento Ácido do Dente/métodos , Animais , Compostos Inorgânicos de Carbono/química , Bovinos , Lâmpadas de Polimerização Dentária , Preparo da Cavidade Dentária/classificação , Cimentos Dentários/química , Infiltração Dentária/classificação , Polimento Dentário/métodos , Restauração Dentária Permanente/classificação , Diamante/química , Corantes Fluorescentes , Processamento de Imagem Assistida por Computador , Cura Luminosa de Adesivos Dentários/métodos , Doses de Radiação , Distribuição Aleatória , Rodaminas , Compostos de Silício/química , Propriedades de Superfície , Temperatura , Fatores de Tempo , Água/químicaRESUMO
O crescente interesse dos pacientes por restaurações estéticas proporciona o surgimento de novos materiais e técnicas restauradoras. A associação de diferentes materiais dentários requer planejamento reabilitador minucioso, para se obter prognóstico favorável ao tratamento. Este trabalho relata um caso clínico de reabilitação bucal com próteses fixas, demonstra todas as etapas clínicas do tratamento e enfatiza o planejamento, os preparos cavitários, a confecção das próteses provisórias, os procedimentos de moldagem, a prova das infraestruturas, o ajuste estético das cerâmicas e a cimentação final. Conclui-se que a reabilitação devolveu ao paciente função mastigatória e estética...
The increasing interest of the patient for esthetic restorative procedures led to the introduction of novel materials and techniques. The association of different types of dental materials demands a comprehensive rehabilitation planning to achieve a favorable prognostic. The aim of this work was to report a case of extensive oral rehabilitation with fixed prosthesis showing the step-by-step treatment, emphasizing treatment planning, preparation, provisionalization, impression taking, clinical adjustments of copings and veneering material, and final luting. It can be concluded that the resulting rehabilitation provided the patient´s masticatory and esthetic function...
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Humanos , Masculino , Adulto , Porcelana Dentária , Prótese Dentária , Planejamento de Dentadura , Estética Dentária , Reabilitação BucalRESUMO
As lesões oclusais denominadas cáries ocultas têm sido muito observadas na prática clínica nos últimos anos, e são evidenciadas com auxílio de radiografia interproximal. Essas lesões acometem pequena parte da superfície do esmalte oclusal e progridem rapidamente pela dentina. Restabelecer a estética, a função e anatomia dos dentes posteriores tem sido, cada vez mais, grande desafio para o clínico, em função da maior exigência dos pacientes. A técnica restauradora com resinas compostas e auxílio da matriz oclusal possibilita a reconstrução da estrutura anatômica dental com previsibilidade e segurança. Este trabalho demonstra, com um relato de caso clínico, a técnica restauradora com resina composta e matriz oclusal em um primeiro molar inferior, acometido por lesão de cárie oculta...
Hidden caries have been commonly observed in dental practice in the last years, and their presence can be confirmed by bitewing radiographs. These lesions initiate in enamel subsurface and advance quickly to dentin. The reestablishment of esthetics, function and anatomy of posterior teeth is a significant challenge for the professional, due to the high demand by the patient. Restorative techniques using composite resins and an occlusal matrix make possible the reconstruction of the dental anatomy. The aim of this case report is to demonstrate a restorative technique using composite resin and an occlusal matrix in a first mandibular molar presenting hidden caries lesion...
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Humanos , Feminino , Adolescente , Resinas Compostas , Cárie Dentária , Dentição Permanente , Estética DentáriaRESUMO
O aumento na expectativa de vida da população e a preocupação com a qualidade de vida têm motivado os pacientes com edentulismo total a buscar os consultórios odontológicos para realizar tratamento reabilitador. Este trabalho relata um caso clínico de prótese total superior e inferior, com o objetivo de demonstrar os aspectos clínicos da confecção das próteses desde o exame clínico, procedimentos de moldagem, determinação da dimensão vertical de oclusão e estética dos dentes e da gengiva
Increasing life expectancy of population and awareness with life quality led edentulous patients to seek for rehabilitation treatment in dental practice. This article is a case report of complete dentures, showing clinical aspects such as initial clinical examination, impression-taking procedures, proper occlusal height dimension, and tooth and gingival esthetics
Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Planejamento de Dentadura , Prótese Total , Dentaduras , Reabilitação BucalRESUMO
During clinical practice, when performing prosthetic rehabilitation with single crowns, improper reproduction of the dental contour by the dental laboratory is a common occurrence. Therefore, the present study evaluated the fidelity of the reproduction of the buccal contour in an upper left canine performed by three Dental Prosthesis Technicians (DPT) using the indirect laminate veneer technique. First, the DPTs confected the veneers based on a model obtained from the upper arch of a dental dummy, containing a replica of an upper left canine with a prosthetic preparation for a laminate veneer. Then, the same DPTs received other identical models, now with the replica of the upper left canine with no preparation, to be used as an anatomical reference for confecting the laminate veneers. The laminate veneers were then bonded to the plaster models and had their buccal contour individually measured. Measurements were also made of the buccal contour of the reference canine. The data were analyzed by ANOVA and the t-test (p = 0.05). Results showed 100% of buccal overcontour when the laminate veneers were compared to the reference canine, regardless of which DPT confected the veneer and regardless of using or not the anatomical reference. The DPTs who participated in the present study were unable to acomplish a faithful anatomical reproduction of the buccal contour, creating an overcontour in all samples. This situation may be responsible for increasing the probability of periodontal and esthetic harm in clinical practice.
Assuntos
Coroas , Dente Canino , Técnica de Moldagem Odontológica/normas , Planejamento de Prótese Dentária , Facetas Dentárias , Planejamento de Prótese Dentária/normas , Planejamento de Dentadura/normas , HumanosRESUMO
PURPOSE: To evaluate the influence of five curing methods on contraction stress, stress rate, and degree of conversion (DC) of a composite and on bond strength of composite restoratives. METHODS: For the stress test, composite was applied between two 5-mm diameter glass rods, mounted in a servohydraulic machine. Stress rates were calculated as the change in stress vs. time. DC was measured by FTIR. Bond strength testing was performed using a push-out test in bovine incisors. The C-factor was 3.0 for all tests. Five methods were evaluated: High Intensity LED (LED HI), Continuous Halogen Light (QTH CL), Medium Intensity LED (LED MI), Low Intensity LED (LED LI), and Pulse Delay Halogen Light (QTH PD). Results were analyzed by ANOVA and Tukey's test (alpha = 0.05). RESULTS: Stress values ranged from 9.25 MPa (QTH PD) to 10.46 MPa (LED MI). No statistical difference was observed among the methods. Bond strength values ranged from 24.6 MPa (LED HI) to 35.4 MPa (QTH PD), with the QTH PD presenting a statistically higher value compared to the other methods. Stress rate and bond strength presented an inverse linear correlation (r2 = 0.79). LED HI presented the highest maximum stress rate, followed by LED MI, QTH CL, LED LI, and QTH PD. The reduction in stress rate observed for the low intensity groups was associated with a general increase in bond strength, with no adverse effect on the degree of conversion of the restorative composite.
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Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária , Adaptação Marginal Dentária , Cura Luminosa de Adesivos Dentários , Animais , Bovinos , Resinas Compostas/química , Análise do Estresse Dentário , Halogênios , Dureza , Transição de Fase , Semicondutores , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
PURPOSE: Symmetry is one of the factors that contributes to facial harmony, and in oral rehabilitation it determines the success of esthetic treatment. Therefore, the aim of the present study was to analyze the axial symmetry between the bipupillar midline and maxillary central incisors midline of 102 dental students (both genders) distributed across five Brazilian dental schools. MATERIALS AND METHODS: Students with no teeth missing and who had never been subjected to any dental treatment were selected. Photographs were taken with a Dental Eye III camera with a 100-mm macro objective and ratio of 1:10 from natural size, recorded on an Ektachrome ASA/ISO 100 film. The images were developed and applied to Microsoft Office Power Point 2007 software. The results were analyzed by analysis of variance and Student's t-test (alpha = 0.05). RESULTS: There was no significant correlation between bipupillar midline and the maxillary dental midline, irrespective of gender. CONCLUSION: No significant coincidence was observed between the interpupillary and dental midline. However, the interpupillar distance and its relationship with other anatomic structures may be used as a reference in treatment, but measurements must be assessed individually. CLINICAL SIGNIFICANCE: Anatomic measurements and facial proportions can be helpful during the planning of esthetic oral rehabilitation.
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Cefalometria/métodos , Olho/anatomia & histologia , Incisivo/anatomia & histologia , Maxila/anatomia & histologia , Estética , Estética Dentária , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Nariz/anatomia & histologia , Fotografia Dentária/métodos , PupilaRESUMO
This study verified the influence of curing methods and light sources on contraction stress, stress rate and degree of conversion (DC) of a restorative composite at two C-factor (CF) levels. For the stress test, composite (0.84 mm thick) was applied between two glass rods 5-mm in diameter mounted in a servohydraulic testing machine. Stress rates were calculated as the change in stress vs time at each second. DC was measured by micro-FTIR. Five curing methods were tested at two C-factor levels (1.5 and 3.0): High Intensity LED (LED HI), Continuous Light (QTH CL), Medium Intensity LED (LED MI), Low Intensity LED (LED LI) and Pulse Delay (QTH PD). The results were analyzed by ANOVA and Tukey's test (alpha = 0.05). For the stress test at CF 1.5, QTH PD presented lower values than LED HI, QTH CL and LED LI. At CF 3.0, no difference was observed among the curing methods. For all curing methods, stress values at CF 3.0 were statistically higher than those at CF 1.5. LED HI presented the highest maximum stress rate, followed by QTH CL, LED MI, LED LI and QTH PD for both C-factors. In the DC test, no difference was observed among the methods and between the C-factor levels.
Assuntos
Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária , Materiais Dentários/efeitos da radiação , Resinas Compostas/química , Lâmpadas de Polimerização Dentária/classificação , Materiais Dentários/química , Adesivos Dentinários/química , Vidro/química , Humanos , Luz , Teste de Materiais , Polímeros/química , Doses de Radiação , Cimentos de Resina/química , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Fatores de TempoRESUMO
During clinical practice, when performing prosthetic rehabilitation with single crowns, improper reproduction of the dental contour by the dental laboratory is a common occurrence. Therefore, the present study evaluated the fidelity of the reproduction of the buccal contour in an upper left canine performed by three Dental Prosthesis Technicians (DPT) using the indirect laminate veneer technique. First, the DPTs confected the veneers based on a model obtained from the upper arch of a dental dummy, containing a replica of an upper left canine with a prosthetic preparation for a laminate veneer. Then, the same DPTs received other identical models, now with the replica of the upper left canine with no preparation, to be used as an anatomical reference for confecting the laminate veneers. The laminate veneers were then bonded to the plaster models and had their buccal contour individually measured. Measurements were also made of the buccal contour of the reference canine. The data were analyzed by ANOVA and the t-test (p = 0.05). Results showed 100 percent of buccal overcontour when the laminate veneers were compared to the reference canine, regardless of which DPT confected the veneer and regardless of using or not the anatomical reference. The DPTs who participated in the present study were unable to acomplish a faithful anatomical reproduction of the buccal contour, creating an overcontour in all samples. This situation may be responsible for increasing the probability of periodontal and esthetic harm in clinical practice.
Assuntos
Humanos , Coroas , Dente Canino , Planejamento de Prótese Dentária , Facetas Dentárias , Técnica de Moldagem Odontológica/normas , Planejamento de Prótese Dentária/normas , Planejamento de Dentadura/normasRESUMO
The aim of this study was to evaluate the effect of different curing methods on the stress generated by the polymerization shrinkage of a restorative composite in two moments: immediately after light exposure and after 5 min. Photoactivation was performed using two different light sources: (1) xenon plasma arc (PAC) light (1,500 mW/cm2 - 3s) and (2) a quartz-tungsten-halogen (QTH) light with three light-curing regimens: continuous exposure (40 s at 800 mW/cm2 - CL); soft-start (10 s at 150 mW/cm2 and 30 s at 800 mW/cm2 - SS) and intermittent light [cycles of 4 s (2 s with light on at 600 mW/cm2 and 2 s of light off), for 80s - IL]. The composite resin was applied between two 5-mm diameter metallic rods, mounted in a servohydraulic machine. The maximum stress was recorded immediately after light exposure (FF) and after 5 min (5F). The results were submitted to ANOVA and Tukey's test (5%). For each method, the results obtained in FF and 5F were, respectively: CL (3.58 and 4.46 MPa); SS (2.99 and 4.36 MPa); IL (3.11 and 4.32 MPa) and PAC (0.72 and 3.27 MPa). The stress generated by the polymerization shrinkage during light exposure can be associated with the photoactivation method used. A significant increase in the stress level was observed during the post-curing period up to 5 min, for all evaluated methods.
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Resinas Compostas/efeitos da radiação , Análise do Estresse Dentário , Cura Luminosa de Adesivos Dentários/métodos , Cimentos de Resina/efeitos da radiação , Lâmpadas de Polimerização Dentária , Halogênios , Teste de Materiais , Transição de Fase , Fatores de Tempo , XenônioRESUMO
The aim of this study was to evaluate the effect of different curing methods on the stress generated by the polymerization shrinkage of a restorative composite in two moments: immediately after light exposure and after 5 min. Photoactivation was performed using two different light sources: (1) xenon plasma arc (PAC) light (1,500 mW/cm2 - 3s) and (2) a quartz-tungsten-halogen (QTH) light with three light-curing regimens: continuous exposure (40 s at 800 mW/cm2 - CL); soft-start (10 s at 150 mW/cm2 and 30 s at 800 mW/cm2 - SS) and intermittent light [cycles of 4 s (2 s with light on at 600 mW/cm2 and 2 s of light off), for 80s - IL]. The composite resin was applied between two 5-mm diameter metallic rods, mounted in a servohydraulic machine. The maximum stress was recorded immediately after light exposure (FF) and after 5 min (5F). The results were submitted to ANOVA and Tukey's test (5 percent). For each method, the results obtained in FF and 5F were, respectively: CL (3.58 and 4.46 MPa); SS (2.99 and 4.36 MPa); IL (3.11 and 4.32 MPa) and PAC (0.72 and 3.27 MPa). The stress generated by the polymerization shrinkage during light exposure can be associated with the photoactivation method used. A significant increase in the stress level was observed during the post-curing period up to 5 min, for all evaluated methods.
Assuntos
Resinas Compostas/efeitos da radiação , Análise do Estresse Dentário , Cura Luminosa de Adesivos Dentários/métodos , Cimentos de Resina/efeitos da radiação , Lâmpadas de Polimerização Dentária , Halogênios , Teste de Materiais , Transição de Fase , Fatores de Tempo , XenônioRESUMO
OBJECTIVE: Modulated curing methods could lead to a higher probability of bond preservation. Therefore, the aim of this study was to evaluate the effect of 7 curing methods on bond strength of composite resin restorations. METHOD AND MATERIALS: Seventy bovine incisors were selected. A conical cavity was prepared in the buccal surface. Adper Single Bond adhesive system was applied according to the manufacturer's instructions, and the cavities were filled with a single increment of Esthet X (Dentsply/Caulk). The specimens were randomly assigned into 7 groups (n = 10) according to the photoactivation method: (1) continuous light 700 (700 mW/cm2) (control); (2) continuous light 150 (150 mW/cm2); (3) continuous light 250 (250 mW/cm2); (4) soft-start 75 (75 mW/cm2) + 700 mW/cm2); (5) soft-start 150 (150 mW/cm2 + 700 mW/cm2); (6) pulse-delay (150 mW/cm2 + 3 minutes + 700 mW/cm2); and (7) intermittent light (cycles at 600 mW/cm2). The energy density for all groups was 14 J/cm2. The bond strength of the composite restorations was measured by performing the push-out test in a universal testing machine (Instron). The results were submitted to ANOVA and Tukey test (P < .05). RESULTS: Pulse-delay, soft-start 150, and soft-start 75 methods showed a significant increase in bond strength when compared with the control continuous light 700 method. Low power density and intermittent light groups showed intermediate results. CONCLUSION: Modulation of the energy density during light curing of composite resins using pulse-delay or soft-start methods increased the bond strength of composite restorations.
Assuntos
Resinas Compostas/efeitos da radiação , Colagem Dentária , Cimentos de Resina/efeitos da radiação , Análise de Variância , Animais , Bis-Fenol A-Glicidil Metacrilato/efeitos da radiação , Bovinos , Adaptação Marginal Dentária , Restauração Dentária Permanente , Análise do Estresse Dentário , Luz , Teste de Materiais , Transição de Fase , Distribuição AleatóriaRESUMO
OBJECTIVES: Verify the influence of curing methods on contraction stress, stress rate, and degree of conversion (DC) of a restorative composite and on bond strength of composite restoratives. METHODS: For the stress test, composite (0.84 mm thick) was applied between two 5-mm diameter glass rods, mounted in a servohydraulic machine. Stress rate was taken by the value of stress/time at each second. DC was measured by micro-FTIR. Bond strength testing was performed using a push-out test. The C-factor in all tests was 3.0. Four curing methods were tested: continuous light (CL), soft-start (SS), and two pulse delay methods using different initial irradiances--150 mW/cm(2) (PD150) and 80 mW/cm(2) (PD80). Results were analyzed by ANOVA and Tukey's test (alpha=0.05). RESULTS: Stress values ranged from 7.9 MPa (PD80) to 10.3 MPa (CL). No statistical difference was verified among CL, SS, and PD150. PD80 presented statistically lower stress values compared to CL and SS. CL presented the highest maximum stress rate, followed by SS, PD150 and PD80. Mean DC values ranged from 54.2% (PD150) to 55.9% (PD80), with no difference observed among the methods. For the bond strength test, values ranged from 26.4 MPa (CL) to 35.5 MPa (PD150). PD150 and PD80 were both statistically superior to SS and CL. SS presented statistically higher bond strength compared to CL. CONCLUSIONS: Modulated curing methods were shown to be effective in reducing contraction stress rate and improving the strength of the bonded interface, and without compromising the DC of the restorative composite.
Assuntos
Resinas Compostas/efeitos da radiação , Colagem Dentária , Restauração Dentária Permanente/métodos , Luz , Animais , Bovinos , Equipamentos Odontológicos , Adaptação Marginal Dentária , Dureza , Teste de Materiais , Transição de Fase , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse MecânicoRESUMO
OBJECTIVE: This study evaluated the relationship between bond strength and marginal and internal adaptation of composite restorations photocured using different methods with a quartz-tungsten-halogen light. MATERIAL AND METHODS: A push-out test was performed to evaluate bond strength of conical restorations in 50 bovine incisors. To evaluate marginal (external) and internal restoration adaptation, 50 circular all-enamel margin preparations were done in bovine incisors. For both tests, the preparations were filled with Esthet*X resin composite. Specimens were distributed into 5 groups (n=10) depending on photoactivation method: G1: continuous light 700; G2: continuous light 150; G3: soft-start; G4: intermittent light; and G5: pulse-delay. The energy density for each method was standardized: 14 J/cm2. Caries Detector (Kuraray) was placed in restoration margins for detection of marginal adaptation. The percentage of interfaces present as gaps was determined using digital images. Specimens were then sectioned, stained, and the internal adaptation was recorded in a similar manner. Data were submitted to ANOVA and the Tukey HSD test, pre-set alpha = 0.05. RESULTS: Bond strength G5 (7.2 MPa+/-1.3) was significantly greater (p=0.00280) than G1 (4.6 MPa+/-1.5). G2, G3, and G4 showed equivalent, intermediate strength values. No significant difference was found in marginal adaptation of any of the groups (p=0.16911). Internal adaptation results were the inverse of strength results: G5 (2.8%+/-4.9) showed significantly less (p=0.00979) gap formation compared to G1 (10.1%+/-6.2). CONCLUSION: Some modulated photocuring methods can increase bond strength while decreasing internal gap formation. An inverse relationship was found between push-out bond strength and internal adaptation. Marginal adaptation was not affected by any photoactivation method.