Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 81
Filtrar
1.
J Prosthet Dent ; 2021 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-33454110

RESUMEN

STATEMENT OF PROBLEM: Redesigned mixing tips, promising less impression material waste, have been marketed. However, whether their use adversely affects the dimensional stability and detail reproduction of the impression material is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the dimensional stability, detail reproduction, and material waste of different polyvinyl siloxane impression materials (regular and light-body) mixed with 2 different mixing tips (MIXPAC T-Mixer mixing tip and MIXPAC helical mixing tip). MATERIAL AND METHODS: Six different polyvinyl siloxane impression materials were used in 2 different consistencies: Virtual Monophase and Virtual Light Body (Ivoclar Vivadent AG), Express XT Regular and Express XT Light Body (3M ESPE), and Panasil initial contact Regular and Panasil initial contact Light (Kettenbach). The polyvinyl siloxane impression materials were mixed with 2 different mixing tips: conventional helical and T-Mixer (n=10). The specimens were prepared in a metal matrix as per specification #19 of the American National Standards Institute/American Dental Association (ANSI/ADA) and International Organization for Standardization (ISO) 4823:2015. The materials were mixed with both mixing tips as per the manufacturer's instructions, inserted into a perforated custom tray on the matrix, and allowed to polymerize completely. The dimensional stability was calculated based on the measurement of the reproduction of lines engraved in the metal matrix. Detail reproduction was evaluated through analysis of continuity and reproducibility of those lines, immediately, 7 days, and 14 days after polymerization. Material waste was assessed by the difference between the initial (before mixing) and final weight (after complete polymerization) of both mixing tips. The data on dimensional stability and detail reproduction among the materials were submitted to the Kruskal-Wallis test, followed by the Student-Newman-Keuls test (α=.05). Comparison between the mixing tips was carried out with the Mann-Whitney test (α=.05), while the comparison among the periods of analysis (immediate, 7 days, and 14 days) was carried out with the Friedman test (α=.05). The data on material waste between the mixing tips were submitted to 1-way ANOVA, followed by the Tukey honestly significant difference tests (α=.05). RESULTS: The T-Mixer mixing tip resulted in reduced material waste. For dimensional stability, Virtual Light mixed with T-Mixer resulted in lower dimensional change (0.53 ±0.58%) compared with the helical mixing tip (1.09 ±0.43%). Among the materials, Panasil Light presented higher values of dimensional change at immediate and 7-day analysis when mixed with T-Mixer tip with a statistical difference compared with Express Light, Virtual Light, and Panasil Regular (P<.05). In general, both mixing tips provided similar results in all periods of analysis (P>.05) for qualitative analysis of detail reproduction. CONCLUSIONS: The T-Mixer tip resulted in less material waste compared with the helical mixing tip. In general, light-body materials showed higher dimensional stability when the T-Mixer tip was used compared with the conventional tip. In general, reduced detail reproduction was observed after periods longer than 7 days after impression making.

2.
Photodiagnosis Photodyn Ther ; 33: 102193, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33503518

RESUMEN

BACKGROUND: Although photodynamic therapy associated with photosensitizers can promote microbial reduction, studies evaluating the consequences of two photodynamic therapy sessions associated with different photosensitizers on the bond strength of glass-fiber posts to endodontically treated intraradicular dentin are scarce. This in vitro study aimed to investigate the influence of two photodynamic therapy sessions using methylene blue or curcumin photosensitizers on the bond strength of glass-fiber posts to intraradicular dentin in different root thirds. METHODS: Seventy-two teeth were divided into 9 experimental groups according to photosensitizer type, concentration and light-activation: Control - deionized water; Methylene blue 50 mg/L; Methylene blue 50 mg/L + laser; Methylene blue 100 mg/L; Methylene blue 100 mg/L + laser; Curcumin 500 mg/L; Curcumin 500 mg/L + LED; Curcumin 1000 mg/L; and Curcumin 1000 mg/L + LED. Push-out bond strength of the fiber posts to endodontically treated dentin was evaluated using a universal test machine (n = 8). Bond strength data underwent Kruskal-Wallis test, followed by Dunn test for comparison between treatments, and Friedman test for comparison between thirds (α = 0.05). Illustrative scanning electron microscopy images were obtained to qualify the failure mode. RESULTS: Curcumin at higher concentration, activated or not by blue LED, decreased the bond strength values in the apical region when compared with the control group (P < 0.05). There was no difference between two photodynamic therapy sessions using methylene blue photosensitizer (activated or not) and the control group regardless of concentrations and root canal depth evaluated (P > 0.05). Regarding intraradicular depth, the different thirds showed no statistical difference on bond strength values (P > 0.05). All experimental groups presented predominance of mixed-type failure, excepting the methylene blue group at higher concentration activated by red laser, and the curcumin photosensitizer at both concentrations activated by blue LED. CONCLUSIONS: Methylene blue at a 50 mg/L concentration can be applied in two PDT sessions, after biomechanical preparation and before glass-fiber post luting, as it presents no influence on root dentin bond strength in in vitro conditions.

4.
Photodiagnosis Photodyn Ther ; : 102141, 2020 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-33307228

RESUMEN

BACKGROUND: The purpose of this study was to investigate the effect of a novel dental bleaching technique with Violet LED on enamel color change, bond strength and hybrid layer nanomechanical properties in resin-dentin restoration, and dentin biostability. METHODS: A total of 125 bovine incisors were distributed into a control group, violet LED group (LED), and 35% peroxide hydrogen bleaching gel (BLG) groups (n = 15). Three 45-minute sessions were performed for both bleaching procedures every week. Enamel color change (ΔE, ΔL, and Δb) was determined after every bleaching session. After color analysis, dentin was exposed for the resin-dentin bond strength analysis using microtensile test and evaluation of the nanomechanical properties at the hybrid layer (nanohardness). While half of the specimens were tested immediately, the remaining were evaluated after 10,000 thermal cycles (TC). Thirty additional teeth were used to investigate dentin ultimate tensile strength (UTS) after the bleaching treatments. UTS was evaluated before and after an enzymatic challenge. Two-way repeated measures ANOVA and Tukey's post-test were used for the statistical analysis (α = 0.05). RESULTS: Enamel bleaching effect was observed in the LED and BLG groups with significant alterations in the ΔE, ΔL, and Δb in the BLG group. No difference was observed in the resin-dentin bond strength among the groups (p > 0.05), however, TC negatively affected the bond strength values for all the groups. Nanomechanical properties ​​remained unchanged when comparing immediate and after TC results (p > 0.05). Bleaching with BLG reduced significantly the dentin UTS, while all groups showed major decrease in UTS after the enzymatic challenge. CONCLUSIONS: Although violet LED was able to promote a bleaching effect, less color changes was observed when compared to BLG. None of the bleaching techniques affected the resin-bond strength or the nanomechanics of the hybrid layer. Violet LED did negatively affect dentin biostability as observed for BLG and it may promote less changes to the organic content of dentin.

6.
Oral Health Prev Dent ; 18(1): 747-756, 2020 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-32895658

RESUMEN

PURPOSE: This in vitro study evaluated the effectiveness of polyacrylic acid as an acid etchant similar to phosphoric acid and its effect on the microtensile bond strength of self-adhesive resin cement to enamel. MATERIALS AND METHODS: Ninety Te-Econom Plus resin blocks (11 x 4 mm) were cemented onto bovine enamel and distributed into 10 groups according to the surface treatments (no surface treatment; etching with 37% phosphoric acid; etching with 20% polyacrylic acid; etching with 37% phosphoric acid + dental adhesive, and etching with 20% polyacrylic acid + dental adhesive) and the self-adhesive resin cements used (RelyX U200 and MaxCem Elite) (n = 9). After bonding, the specimens were sectioned into sticks, subjected to thermocycling (5760 cycles, 5°C and 55°C) and microtensile bond strength testing (n = 6). Images of representative specimens were obtained using a scanning electron microscope. Enamel penetration evaluation of different surface treatments was analysed by confocal laser scanning microscopy (n = 3). Data on bond strength were subjected to 2-way ANOVA and Tukey's least significant difference test (α = 0.05). RESULTS: Both 37% phosphoric acid and 20% polyacrylic acid yielded the same microtensile bond strength between self-adhesive resin cement and enamel, independent of the application of dental adhesives (p > 0.05). MaxCem Elite showed higher bond strength values than RelyX U200 just for the 20% polyacrylic acid group (p = 0.001). CONCLUSION: Acid pre-conditioning of dental enamel may influence the bond strength of self-adhesive resin cement to enamel, and 20% polyacrylic acid showed efficacy similar to that of 37% phosphoric acid.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Grabado Ácido Dental , Resinas Acrílicas , Animales , Bovinos , Resinas Compuestas , Cementos Dentales , Esmalte Dental , Análisis del Estrés Dental , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Resistencia a la Tracción
7.
Braz Oral Res ; 34: e063, 2020 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-32609232

RESUMEN

This in vitro study aimed to evaluate the effects of different luting protocols on the thickness of luting interface of ceramic laminate veneers. Thirty-six lithium disilicate blocks (7 × 8 × 0.6 mm) were cemented onto bovine enamel. They were divided into 6 groups based on the luting protocol (no previous photoactivation of the dental adhesive; previous activation of the dental adhesive only on enamel surface; and previous photoactivation of the dental adhesive on both the enamel surface and inner surface of ceramic laminate) and the luting materials used (Single Bond Universal/RelyX Veneer and Tetric N Bond/Variolink Veneer). The luting interface thickness of ceramic laminate veneers was evaluated using a laser scanning confocal microscope (n = 6). The luting interface measurements were analyzed using 2-way ANOVA and the Tukey least significant difference test (α = 0.05). Prior activation of the adhesive on the dental enamel and inside the ceramic laminate exhibited higher luting interface thickness than that with no prior photoactivation of both luting materials (p < 0.05). Specimens cemented with Tetric N Bond/Variolink Veneer, submitted for prior photoactivation of the adhesive on the dental enamel and on both dental enamel and inner surface of ceramic, exhibited lower luting interface thickness than those luted with Single Bond Universal/RelyX Veneer (p < 0.05). The prior photoactivation of dental adhesives influenced the thickness of luting interface in laminate restorations. Tetric N Bond/Variolink Veneer yielded more satisfactory results than Single Bond Universal/RelyX Veneer when the adhesive was light activated.


Asunto(s)
Cerámica , Animales , Bovinos , Recubrimiento Dental Adhesivo , Cementos Dentales , Coronas con Frente Estético , Ensayo de Materiales , Cementos de Resina
8.
J Adv Prosthodont ; 12(2): 55-60, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32377317

RESUMEN

PURPOSE: The aim was to evaluate the effect of four acidic beverages on the roughness (Ra) and color change (ΔEab) of two brands of artificial teeth and a heat-polymerized acrylic resin (HPAR) for use in a prosthetic base. MATERIALS AND METHODS: All materials were divided into 5 groups, according to the used acidic beverage (artificial saliva - control, red wine, orange juice, coke-based, and lemon juice-based soft drink). The immersion process was divided into two stages: T1 - immersion in the acidic solutions for 10 minutes for 14 days; T2 - after T1, the samples were immersed in grape juice for 14 days. The Ra of the samples was evaluated in a rugosimeter and the ΔEab in a spectrophotometer, before and after the immersions. The analysis of variance of one (ΔEab) and two factors (Ra) and Tukey were performed (α=.05). RESULTS: There was a statistical difference for roughness after immersion (T1) for Trilux and Tritone teeth, regardless of the acid solution. For Trilux teeth, all acid solutions increased Ra (P<.05). For Tritone teeth, only the coke-based soft drink did not statistically change Ra. Grape juice (T2) altered Ra only of artificial teeth (P<.05). The color was changed for all materials, after T1 and T2. CONCLUSION: In general, the acidic solutions changed the Ra and ΔEab of HPAR and artificial teeth after T1. The grape juice altered the roughness only of the artificial teeth, promoting a clinically acceptable color change in the materials.

9.
Int J Oral Maxillofac Implants ; 35(3): 479-484, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32406643

RESUMEN

PURPOSE: This in vitro study evaluated the effectiveness of a sealing agent on vertical misfit of the implant-abutment interface in an external hexagon implant system before and after mechanical cyclic loading. Effects on preload maintenance of retaining screws after mechanical cycling were also assessed. MATERIALS AND METHODS: External hexagon implant systems were divided into two groups (n = 12) according to the presence of an anaerobic sealing gel (control group-no sealing gel; experimental group-sealing gel applied). A prefabricated UCLA abutment was attached to the external hexagon implant with a digital torque wrench in accordance with the recommendations of the manufacturer. Specimens were tested through mechanical cyclic loading (1 × 106 cycles, 2 Hz, and 130 N). Vertical misfit of the implant-abutment interface was analyzed using a stereomicroscope, and reverse torque values were obtained using a digital wrench. Misfit and reverse torque data were measured and analyzed via analysis of variance (ANOVA) and the Tukey least significant difference test (α = .05). RESULTS: The sealing gel promoted lower vertical misfit values in the test group after mechanical cycling compared with before cycling (P = .009). The control group showed lower reverse torque values for retaining screws compared with the initial torque after mechanical cyclic loading (P < .0001). However, sealing gel application promoted higher reverse torque values in the test group postcycling (P = .0003). CONCLUSION: Anaerobic sealing agent application improved vertical misfit of the implant-abutment interface and preload maintenance of screw-retained implant-supported prostheses post-mechanical cycling.


Asunto(s)
Pilares Dentales , Implantes Dentales , Diseño de Implante Dental-Pilar , Prótesis Dental de Soporte Implantado , Análisis del Estrés Dental , Torque
10.
Oral Health Prev Dent ; 18(1): 145-152, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32238986

RESUMEN

PURPOSE: To evaluate the microtensile bond strength of dentine/self-adhesive resin cement interface after several treatments on a dentine surface. MATERIALS AND METHODS: Twenty-eight human molars were selected and divided into four groups: no treatment (control (C)); 2% chlorhexidine digluconate (CHX); 25% polyacrylic acid (PA); and 23 ppm dispersive solution of silver nanoparticle (SN). Prepolymerised TPH resin composite (Dentsply) blocks were luted on the dentine surface using RelyX U200 self-adhesive resin cement (3M ESPE). Microtensile bond strength was measured (MPa) in a universal testing machine 24 h and 6 months after the bonding process. The fractured specimens were examined in an optical microscope and classified according to the fracture pattern. A representative sample of each group was observed by scanning electronic microscope. Data were submitted to analysis of variance (ANOVA) and Tukey's test to compare the mean among the groups (p <0.05). RESULTS: The highest microtensile bond strength values after 24 h were found for the PA group (13.34 ± 6.36 MPa), with no statistically significant difference for the C group (9.76 ± 3.11 Mpa). After 6 months, the highest microtensile bond strength values were found for the C group (9.09 ± 3.27 Mpa), with statistically significant difference only for the CHX group (2.94 ± 1.66 MPa). There was statistically significant difference only for the PA group when comparing the periods studied. Regardless of the surface treatment applied, there were more adhesive failures in both periods of time. CONCLUSION: Dentinal pretreatment with PA, as well as use of SN before the bonding procedure of self-adhesive resin cement to dentine, may be alternative bonding protocols.


Asunto(s)
Recubrimiento Dental Adhesivo , Nanopartículas del Metal , Resinas Compuestas , Cementos Dentales , Análisis del Estrés Dental , Dentina , Recubrimientos Dentinarios , Humanos , Ensayo de Materiales , Cementos de Resina , Plata , Propiedades de Superficie , Resistencia a la Tracción
11.
Photodiagnosis Photodyn Ther ; 30: 101679, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32014581

RESUMEN

BACKGROUND: To evaluate the bleaching efficacy and post-operative sensitivity of 10 % carbamide peroxide (PC) with or without violet LED (VL). METHODS: Thirty patients were selected and were instructed to perform home bleaching treatment using PC 10 %, for 8 h daily, for 21 days. All patients underwent in-office irradiation of only one hemiarch with VL for 30 min, twice per week for three weeks, totaling six clinical sessions of irradiation. The treatment used for each hemiarch was determined randomly. The analyses were performed at the initial time and 7, 14, and 21 days after the start of treatment and 7 and 14 days after the end of the bleaching treatment. For color analysis, digital spectrophotometry was done using the Visual Analog Scale and cold detection was performed using the thermo-sensory analysis II (TSA II) equipment. The ANOVA-two way with repeated measures and the Tukey test (α = 0.05) were used for the color and cold sensitivity analysis. RESULTS: On analyzing the color change, it was observed that the hemiarch that was irradiated with VL presented the highest values compared with the side that did not receive irradiation. Regarding tooth sensitivity, there was no report of any patient experiencing discomfort during the bleaching protocol. Analysis of the dental thermal sensation threshold showed that the use of VL made the teeth more sensitive. CONCLUSIONS: It can be concluded that the VL provided a positive effect on color alteration when used in conjunction with 10 % PC. However, the use of this new protocol made the teeth more sensitive.

12.
Restor Dent Endod ; 45(1): e12, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-32110540

RESUMEN

Objectives: The aim of this in vitro study was to evaluate the microhardness and surface roughness of composite resins before and after tooth bleaching procedures. Materials and Methods: Sixty specimens were prepared of each composite resin (Filtek Supreme XT and Opallis), and BisCover LV surface sealant was applied to half of the specimens. Thirty enamel samples were obtained from the buccal and lingual surfaces of human molars for use as the control group. The surface roughness and microhardness were measured before and after bleaching procedures with 35% hydrogen peroxide or 16% carbamide (n = 10). Data were analyzed using 1-way analysis of variance and the Fisher test (α = 0.05). Results: Neither hydrogen peroxide nor carbamide peroxide treatment significantly altered the hardness of the composite resins, regardless of surface sealant application; however, both treatments significantly decreased the hardness of the tooth samples (p < 0.05). The bleaching did not cause any change in surface roughness, with the exception of the unsealed Opallis composite resin and dental enamel, both of which displayed an increase in surface roughness after bleaching with carbamide peroxide (p < 0.05). Conclusions: The microhardness and surface roughness of enamel and Opallis composite resin were influenced by bleaching procedures.

13.
Gen Dent ; 68(2): 44-49, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32105226

RESUMEN

The aim of this study was to evaluate the degree of conversion of resin cements polymerized under different ceramic systems. Forty specimens of RelyX ARC (3M ESPE) and Maxcem Elite (Kerr) resin cements were polymerized under 5 types of dental ceramics: feldspathic, aluminum oxide-reinforced, aluminum oxide-based strengthened with zirconium oxide, leucite-reinforced, and lithium disilicate-reinforced. Measurements of the degree of conversion of the resin cements were performed 10 minutes, 1 hour, and 24 hours after curing using a Fourier transform infrared spectrophotometer. The values were subjected to a 3-way repeated-measures analysis of variance, and the means were compared with the Fisher protected least significant difference test (α = 0.05). The study findings showed that RelyX ARC resin cement displayed a higher degree of conversion than Maxcem Elite (P < 0.05). The degree of conversion was significantly lower for RelyX ARC polymerized under aluminum oxide ceramic and aluminum oxide ceramic strengthened with zirconium oxide (P < 0.05). For Maxcem Elite, there was no significant difference in the degree of conversion attained under the various ceramics (P > 0.05). For both cements, the degree of conversion increased gradually up to 24 hours after curing (P < 0.05). The ceramic system used directly influenced the degree of conversion of RelyX ARC. Both resin cements displayed an increase in the degree of conversion over time.


Asunto(s)
Cerámica , Cementos de Resina , Porcelana Dental , Ensayo de Materiales , Polimerizacion
14.
Oral Health Prev Dent ; 18(1): 71-76, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32051973

RESUMEN

PURPOSE: The aim of this in vitro study was to evaluate the influence of preapplication of 2% chlorhexidine gluconate on the immediate microtensile bond strength of a universal adhesive system on dentine subjected to different bonding protocols. MATERIALS AND METHODS: Twenty human molars were used in this study, and the tooth surface was abraded to expose the dentine. The teeth were randomly divided into four groups according to the surface treatment (n = 5): SBU group: Single Bond Universal without acid etching; SBUPA group: 37% phosphoric acid + Single Bond Universal; SBUCG group: 2% chlorhexidine gluconate + Single Bond Universal; and SBUPACG group: 37% phosphoric acid + 2% chlorhexidine gluconate + Single Bond Universal. The microtensile bond strengths were measured using a microtensile tester 24 h after bonding. The bond strength data were subjected to analysis of variance (ANOVA) and Sheffé's least statistically significant difference test (α = 0.05). RESULTS: No statistically significant differences between the analysed groups were observed (p > 0.05). However, conditioning with phosphoric acid without the action of the chlorhexidine gluconate group resulted in higher numerical values of bond strengths than that for the chlorhexidine gluconate without the acid conditioning group. CONCLUSION: The preapplication of 2% chlorhexidine gluconate did not reduce the immediate bond strength of the Single Bond Universal adhesive system under different bonding protocols.


Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Grabado Ácido Dental , Clorhexidina/análogos & derivados , Resinas Compuestas , Cementos Dentales , Dentina , Humanos , Ensayo de Materiales , Proyectos Piloto , Propiedades de Superficie , Resistencia a la Tracción
15.
J Oral Implantol ; 46(2): 163-171, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-31905318

RESUMEN

The purpose of this systematic review was to evaluate the literature available for materials exhibiting the best efficacy in preventing biofilm formation in the interior of implants. We searched PubMed/MEDLINE, Scopus, and Cochrane databases. This review is registered with the PROSPERO database and followed the suitability of the PRISMA protocol. The initial search resulted in 326 articles from the databases. After they were read, 8 articles remained, and the inclusion and exclusion criteria were applied. Six of these 8 articles were classified as in vitro and 2 were classified as in situ. The regions of the implants evaluated ranged from the interface of the pieces to the occlusal upper access of the abutment. The implant connections evaluated the Morse taper, external connection, and internal connection. Meta-analysis of the quantitative data was performed at a significance level of .05. Cotton exhibited poor control of infiltration, even in combination with other materials. Isolated gutta-percha (GP) and polytetrafluoroethylene (PTFE) tape with composite resin (CR) or GP performed better as physical barriers. The best results for chemical barriers were observed by the application of 1% chlorhexidine gluconate (CG) gel, thymol varnish, and the deposition of Ag films onto the surface. The applied meta-analysis did not show a significant difference in comparison between the different types of implant connections (P > .05). The application of CG and thymol varnish antimicrobials was effective in preventing biofilm formation and easy clinical execution; these could be used in combination with CR, GP, and PTFE.


Asunto(s)
Diseño de Implante Dental-Pilar , Implantes Dentales , Biopelículas , Pilares Dentales , Prótesis Dental de Soporte Implantado
16.
Photodiagnosis Photodyn Ther ; 30: 101673, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31988021

RESUMEN

BACKGROUND: There are few studies on the influence of methylene blue as a photosensitiser on the mechanical properties and adhesion of glass-fiber posts to intraradicular dentin. Thus, this in vitro study aimed to evaluate the influence of photodynamic therapy with a methylene blue photosensitizer on the Martens hardness, elastic modulus, and bond strength of glass-fiber posts in different thirds of intraradicular dentin. METHODS: Eighty bovine teeth were divided into the following five groups: a control using deionized water, and four other groups according to the methylene blue concentration (50 mg/L or 100 mg/L) and substrate treatment (with or without red laser action). Ultramicrohardness test was used to evaluate the mechanical properties in different regions of the root dentin (n = 8). Push-out analysis was evaluated using a universal testing machine (n = 8). Data were subjected to the Kruskal-Wallis test, followed by Dunn's test for comparing groups, and the Friedman test for comparing thirds (α = 0.05). Representative scanning electron microscopy images were obtained. RESULTS: In general, methylene blue in distinct concentrations, with or without laser action, did not cause differences in the mechanical properties or bond strength in different regions of root dentin (P > 0.05). Methylene blue at a higher concentration, activated with laser, produced lower bond strength values in the middle third of the root canal (P < 0.05). CONCLUSIONS: Methylene blue at 50 mg/L had no influence on the mechanical properties of the bovine tooth and the bond strength of the glass-fiber posts to intraradicular dentin.

17.
Artículo en Inglés | MEDLINE | ID: mdl-31815983

RESUMEN

The purpose of this study was to evaluate the intensity of light-curing units and its relationship with the color stability and microhardness of composite resins with different shades subjected to a thermocycling procedure. Eighty blocks (5.0 × 2.0 mm) of TPH Spectrum composite resin (Dentsply Sirona) were produced and distributed into four groups according to the light-curing units (EC 450, ECEL; Valo, Ultradent) and color of the resin material (A3; C3) (n = 20). Within each group, color stability was measured on half the sample (n = 10) using a UV-2450 visible UV spectrophotometer (Shimadzu), and Knoop hardness was measured on the other half (n = 10) using an HMV 2000 microhardness tester (Shimadzu) before and after thermocycling (12,000 cycles, 5°C and 55°C). Mann-Whitney test was performed on the color stability data; the microhardness data were analyzed using a three-way analysis of variance (ANOVA) and Tukey test (α = .05). The ANOVA results showed that thermocycling, distinct light intensity, and different colors of resin materials influenced the microhardness of the composite resins, which was evidenced by the A3 composite resin light-cured with a Valo polywave showing higher hardness values. There was no statistical difference in the color stability of the A3 composite resin; however, the C3 composite resin light-cured with an EC 450 singlewave light-curing unit showed higher color alteration values. In general, the Valo polywave light-curing unit imparted better mechanical property and color stability to both shades of the composite resins. The different shades of resin material influenced the hardness of the composite resins. Therefore, the light intensity of the light-curing units should be evaluated and monitored, as the amount of light intensity will interfere in the quality and longevity of resin restorations.


Asunto(s)
Resinas Compuestas , Luces de Curación Dental , Color , Dureza , Ensayo de Materiales
18.
Gen Dent ; 68(1): 72-77, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31859667

RESUMEN

This study evaluated the Martens hardness (HM) and elastic modulus (EIT) of resin cement and dentin underlying the bonding interface of customized glass fiber posts luted to intraradicular dentin and subjected to mechanical cycling. Two null hypotheses were tested: (1) no differences in the mechanical properties (HM and EIT) of the resin cement and underlying dentin would be found between customized and noncustomized glass fiber post groups, with or without mechanical cycling; and (2) no differences in the mechanical properties of the resin cement or underlying dentin would be found between the cervical, middle, and apical thirds of the intraradicular dentin. Forty single-rooted premolars were divided into 4 groups: customized or noncustomized glass fiber post, with or without mechanical cycling. The noncustomized posts were cemented in their original state to prepared canals, while the customized posts were modified with composite resin according to the geometry of the root canal. The specimens in the mechanical cycling groups were positioned at a 45-degree angle in an electromechanical fatigue testing machine and subjected to loading with a steel tip with a 4-mm diameter for 1,200,000 cycles at 50 N. After the specimens were prepared according to the appropriate group protocol, they were sectioned into thirds, and HM and EIT values of the resin cement and dentin underlying the bonding interface were determined using an ultramicrohardness tester under a load of 5 mN. A 2-way repeated-measures analysis of variance with post hoc Tukey test was performed. For resin cement in the cervical region, the highest HM and EIT values were observed in the noncustomized group after mechanical cycling. Similarly, in the underlying dentin, specimens in the noncustomized group after mechanical cycling had the highest HM values in the cervical region. Therefore, customization of glass fiber posts with composite resin is not essential for bonding to intraradicular dentin.


Asunto(s)
Recubrimiento Dental Adhesivo , Vidrio , Técnica de Perno Muñón , Cementos de Resina , Resinas Compuestas , Materiales Dentales , Cavidad Pulpar , Dentina , Ensayo de Materiales , Estrés Mecánico
19.
J Mech Behav Biomed Mater ; 102: 103458, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31605928

RESUMEN

The aim of this study evaluates the surface roughness and gloss of resin composites for bleached teeth, using different modes of light curing and photoinitiators after challenges. Eighty discs were made with Filtek Z350XT (camphorquinone) and Vit-l-escence (camphorquinone, amine and lucerin-TPO). Forty disks were light cured by a monowave LED and forty with a polywave LED. Roughness and gloss analysis were made. The specimens were exposed to brushing and hydrochloric acid (HCl) and analyzed again. The data were analyzed by two-way ANOVA analysis of variance for repeated measures, considering each challenge separately. Afterwards, Tukey test was applied for multiple comparisons (p ≤ 0.05). All resins had a significant increase in roughness after brushing with polywave device and only Vit-l-escence presented significant increased after HCl. Regarding the surface gloss, no influence on light-curing units was found for all resins after toothbrushing and after HCl for Vit-l-escence. All resins showed significant decrease in gloss after the challenges. The type of LED device did not influence the roughness and surface gloss of resin composites for bleached teeth after the challenges.

20.
Braz. oral res. (Online) ; 34: e063, 2020. tab, graf
Artículo en Inglés | LILACS-Express | LILACS, BBO - Odontología | ID: biblio-1132657

RESUMEN

Abstract This in vitro study aimed to evaluate the effects of different luting protocols on the thickness of luting interface of ceramic laminate veneers. Thirty-six lithium disilicate blocks (7 × 8 × 0.6 mm) were cemented onto bovine enamel. They were divided into 6 groups based on the luting protocol (no previous photoactivation of the dental adhesive; previous activation of the dental adhesive only on enamel surface; and previous photoactivation of the dental adhesive on both the enamel surface and inner surface of ceramic laminate) and the luting materials used (Single Bond Universal/RelyX Veneer and Tetric N Bond/Variolink Veneer). The luting interface thickness of ceramic laminate veneers was evaluated using a laser scanning confocal microscope (n = 6). The luting interface measurements were analyzed using 2-way ANOVA and the Tukey least significant difference test (α = 0.05). Prior activation of the adhesive on the dental enamel and inside the ceramic laminate exhibited higher luting interface thickness than that with no prior photoactivation of both luting materials (p < 0.05). Specimens cemented with Tetric N Bond/Variolink Veneer, submitted for prior photoactivation of the adhesive on the dental enamel and on both dental enamel and inner surface of ceramic, exhibited lower luting interface thickness than those luted with Single Bond Universal/RelyX Veneer (p < 0.05). The prior photoactivation of dental adhesives influenced the thickness of luting interface in laminate restorations. Tetric N Bond/Variolink Veneer yielded more satisfactory results than Single Bond Universal/RelyX Veneer when the adhesive was light activated.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...