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1.
Oper Dent ; 45(6): E280-E288, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33215201

RESUMO

CLINICAL RELEVANCE: Acid-functional monomers in self-adhesive resin cements may decrease their self-curing polymerization ability. Light irradiation optimizes polymerization performance. SUMMARY: Purpose: The aim of this study was to investigate Knoop microhardness of self-adhesive resin cements under dual- and self-curing modes in simulated canals for describing the polymerization behavior.Methods and Materials: Slots in lightproof silicone cylinders with one open end were filled with the following eight materials: a traditional resin cement (Duolink), a core build-up resin material (MultiCore Flow), and six self-adhesive resin cements (RelyX Unicem 2, G-Cem Automix, Maxcem, Biscem, Multilink Speed, and PermaCem 2.0). The resins were exposed to light through the open end and then stored in a lightproof box. The Knoop hardness gradient for each resin was measured after 1 hour and 120 hours. Surface readings were obtained at 1-mm intervals from 1 mm to 10 mm away from the open ends. The data were analyzed by two-way analysis of variance and the Student-Newman-Keuls test (α=0.05).Results: All the resin materials had stable Knoop hardness numbers (KHNs) at a certain depth; their KHNs in the self-curing mode did not change (p>0.05). The region above this certain depth was regarded as having undergone the dual-curing mode, and the KHN decreased gradually with depth (p<0.05). Between 1 and 120 hours postexposure, the ratio of the KHN at a 5-mm depth (self-cured) to that at a 1-mm depth (dual-cured) increased in Duolink and MultiCore Flow. However, the ratios of the six adhesive resin cements varied.Conclusion: Without light, most self-adhesive resin cements differed from traditional dual-cured resin materials in terms of Knoop micro-hardness, and they had a lesser capacity for chemical-induced curing.


Assuntos
Cimentos Dentários , Cimentos de Resina , Dureza , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Polimerização , Autocura de Resinas Dentárias
2.
Oper Dent ; 45(5): E255-E270, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33170938

RESUMO

CLINICAL RELEVANCE: Non-carious cervical lesion restorations using a dual-cure universal adhesive in self-etch and etch-and-rinse mode showed satisfactory clinical performance after 18 months. SUMMARY: Objectives: The objective of this multicenter, double-blind, split-mouth randomized clinical trial was to evaluate the clinical performance of a new dual-cure universal adhesive system (Futurabond U, Voco GmBH) when applied using different strategies over a period of 18 months.Methods and Materials: Fifty patients participated in this study. Two hundred non-carious cervical lesions were restored using the adhesive Futurabond U according to four adhesive strategies (n=50 per group): only self-etch (SEE), selective enamel etching + self-etch (SET), etch-and-rinse with dry dentin (ERDry), and etch-and-rinse with wet dentin (ERWet). After the adhesive application, cavities were restored using Admira Fusion composite resin. These restorations were evaluated according to FDI World Dental Federation criteria for the following characteristics: retention/fracture, marginal adaptation, marginal staining, postoperative sensitivity, and caries recurrence.Results: After 18 months, only four patients (12 months: one patient, n=4 restorations; and 18 months: three patients, n=12 restorations) were not evaluated. Fourteen restorations were lost after 18 months of clinical evaluation (four for SEE, three for SET, three for ERDry, and four for ERWet). The retention rates for 18 months (95% confidence interval) were 92% (81%-97%) for SEE, 94% (83%-97%) for SET, 94% (83%-97%) for ERDry, and 92% (81%-97%) for ERWet (p>0.05). Thirty-eight restorations were considered to have minor discrepancies in marginal adaptation at the 18-month recall (13 for SEE, 13 for SET, six for ERDry, and six for ERWet; p>0.05). Fourteen restorations were detected as a minor marginal discoloration at the 18-month recall (six for SEE, six for SET, one for ERDry, and one for ERWet; p>0.05). However, all were considered clinically acceptable. No restorations showed postoperative sensitivity or caries recurrence at the time.Conclusion: The clinical performance of the Futurabond U did not depend on the bonding strategy used, and it was considered reliable after 18 months of clinical evaluation, although more marginal discrepancy was observed in the self-etch group.


Assuntos
Colagem Dentária , Cárie Dentária , Resinas Compostas , Cárie Dentária/terapia , Cimentos Dentários , Adaptação Marginal Dentária , Restauração Dentária Permanente , Adesivos Dentinários , Humanos , Cimentos de Resina , Colo do Dente
3.
Beijing Da Xue Xue Bao Yi Xue Ban ; 52(5): 931-937, 2020 Oct 18.
Artigo em Chinês | MEDLINE | ID: mdl-33047732

RESUMO

OBJECTIVE: To study the effect of bioactive glass (BG) on the dentin bond strength and the microleakage of hybrid layer. METHODS: In the study, 30 dentin planes were prepared from the third molars with no caries and equally assigned to the control group, BG group, and sodium trimetaphosphate (STMP)-polyacrylic acid (PAA)-BG group (S-P-BG group), randomly. After etched with 35% phosphoric acid, the dentin planes of BG group were pretreated with 0.5 g/L BG, and the dentin planes of S-P-BG group were pretreated with 5% STMP, 5% PAA and 0.5 g/L BG. No additional pretreatment was done to the dentin planes of control group. Then the dentin planes were bonded using 3M Single Bond 2 adhesive to 3M Z350XT composite resin, and cut into 0.9 mm×0.9 mm column samples, which were stored at 37 ℃ artificial saliva (AS). After 24 hours, 1 month, and 3 months, the microtensile bond strength test was performed. The data were analyzed using one-way ANOVA and LSD method. The morphology of the bond fracture interface was observed with scanning electron microscope. Other 27 teeth were collected and the enamel layer and roots cut off, with the pulp chamber exposed. 0.1% rhodamine B was added to the 3M Single Bond 2 adhesive, and then the adhesive was applied to complete the bonding procedures as above. The teeth were stored in 37 ℃ AS for 24 hours, 1 month, 3 months, and then 0.1% sodium fluorescein solution was placed in the chambers and stained for 1 hour. Confocal laser scanning microscopy was used to observe the interface morphology and microleakage of the hybrid layer. RESULTS: At the end of 24 hours and 1 month, there was no significant difference in the microtensile bond strength among the three groups (P>0.05). After 3 months of soaking, the S-P-BG group [(36.91±7.07) MPa] had significantly higher microtensile bond strength than the control group [(32.73±8.06) MPa] (P=0.026); For the control group and the BG group, the microtensile bond strength significantly decreased at the end of 3 months compared with 24 hours (control group: P=0.017, BG group: P=0.01); The microtensile bond strength of S-P-BG group af the end of 3 months had no significant difference in compared with 24 hours [(37.99±7.98) MPa] (P>0.05). Observation of the fracture surface at the 24 hours showed no obvious mineralization in all the three groups. After 1 and 3 months, mineral formation was observed in BG group and S-P-BG group, and no obvious collagen exposure was observed in S-P-BG group. Confocal laser scanning microscopy revealed no obvious differences in the morphology and quantity of the resin tag in the control group, BG group and S-P-BG group. At the end of 24 hours, leakage was found in all the three groups. The microleakage of the control group increased at the end of 3 months, while the microleakage of the BG and S-P-BG groups decreased. CONCLUSION: BG pretreatment of dentin bonding interface can induce mineralization at the bonding interface and reduce the microleakage of the hybrid layer; pretreating the dentin bonding interface with STMP, PAA and BG may enhance the maintaining of the dentin bonding durability.


Assuntos
Adesivos Dentinários , Cimentos de Resina , Dentina , Vidro , Resistência à Tração
4.
Beijing Da Xue Xue Bao Yi Xue Ban ; 52(5): 943-947, 2020 Oct 18.
Artigo em Chinês | MEDLINE | ID: mdl-33047734

RESUMO

OBJECTIVE: To select the most effective method among different masking treatments, such as different thickness and transparence, tissue surface's opaque coating, and opaque resin cement to restore discolored teeth esthetically by porcelain veneer. METHODS: Four extracted intact maxillary central incisors were prepared for porcelain veneer restoration and each three heat pressed porcelain veneers from three thicknesses (0.8 mm, 1.0 mm, 1.2 mm) and two transparency(high transparence, HT and low transparence, LT))in Vita shade A2 were fabricated for each tooth, in total of 72 pieces. The surfaces of three prepared teeth were then painted to mimic situations of severe dental fluorosis, severe tetracycline teeth, and necrotic teeth. Each of the veneers was temporarily cemented to the corresponding tooth surface using try-in cements with three different colors (transparent, opaque, and yellow), then used the shade guide (3D master) and electronic colorimeter (easy shade) to record the shade of each porcelain veneer through hue, lightness, and chroma reading. After that, high-transparence porcelain veneers in thickness of 0.8 mm was fused with a layer of opaque porcelain in tissue surface, and were shade matched again after cementation. Statistic treatments were performed to analyze the difference in each masking method. RESULTS: For each 0.2 mm increase in the veneer thickness of porcelain, the average lightness was reduced by 1 unit, while the chroma was not changed which was independent of the type of the resin cements. When the thickness of the porcelain veneer was decreased to 0.8 mm, the opacity effect was not remarkable even if a low-transparence porcelain veneer was used. Transparent and yellow resin cements had poor opaque performance, while opaque resin cement could reduce the lightness by 2 units and the chroma was also reduced. The opaque layer of the tissue surface could be applied uniformly, and the lightness and chroma could be reduced to Vita 2M1 to 2M1.5 levels regardless of the color of resin cements, which suggested a stable opacity effect for different discolored teeth in this study. CONCLUSION: For porcelain veneer restoration of discolored teeth, thickened veneers are the most effective means to display a natural transmittance and color. Tissue surface's opacity coatings and opaque resin cements can also be used to reduce grayscale and increase lightness.


Assuntos
Descoloração de Dente , Cor , Humanos , Teste de Materiais , Pigmentação em Prótese , Cimentos de Resina , Descoloração de Dente/terapia
5.
J Adhes Dent ; 22(5): 443-453, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33073776

RESUMO

PURPOSE: To systematically review the literature to determine whether silane combined with adhesive application improves the repair bond strength of direct methacrylate-based resin composites in comparison to the use of an adhesive alone. MATERIALS AND METHODS: The literature up to December 2019 was searched through PubMed/MEDLINE, Scopus, and Lilacs databases with no publication year or language limits. From 676 potentially eligible studies, 81 were selected for full-text analysis, and 19 were included in the systematic review. Two reviewers independently selected the studies, extracted data, and assessed the risk of bias. Meta-analyses were conducted using a random effects model to calculate pooled mean differences between adhesive- vs silane-plus-adhesive surface treatments (global meta-analysis) and considering subgroup analyses (immediate and aged repair bond strengths and type of silane - hydrolyzed or nonhydrolyzed). Statistical analyses were performed using RevMan5.3 at a significance level of 5%. RESULTS: Global meta-analysis showed that the use of silane prior to adhesive application produced significantly higher repair bond strengths (p=0.003). A higher mean difference (effect size: 7.30, 95% CI: 2.91-17.51) between groups was found when nonhydrolyzed silanes were used. The heterogeneity was high. Studies scored between medium and high risk of bias. CONCLUSION: An additional silane application step could increase the repair bond strength of methacrylate-based resin composites.


Assuntos
Colagem Dentária , Silanos , Cimentos Dentários , Teste de Materiais , Cimentos de Resina
6.
J Adhes Dent ; 22(5): 531-538, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33073784

RESUMO

PURPOSE: To evaluate the roughness, surface energy, and the bond strength of lithium disilicate yielded by two different types of nonthermal plasma (NTP), oxygen- or argon-based, compared to the conventional method. MATERIALS AND METHODS: Ninety-three lithium disilicate (IPS e.max Press) samples were divided into 3 groups: HF (hydrofluoric acid group); ONTP (oxygen-based NTP group); ANTP (argon-based NTP group). Surface energy and roughness analyses were performed before and after surface treatment, and bond strength testing was performed before and after 5000 thermocycles. Scanning electron microscopy (SEM) was used to characterize the surface treatments. Data were submitted to ANOVA and Bonferroni's test with statistical significance set at 5%. RESULTS: The ONTP group presented the highest surface energy values, followed by ANTP and HF. In addition, the ONTP group had higher surface roughness. SEM revealed exposed lithium disilicate crystals in the HF group, but a homogeneous film coverage in both NTP groups. Regarding bond strength, ANTP presented statistically significantly higher values than the other groups before thermocycling, and statistically significantly lower values than the other groups after thermocycling. The HF and ONTP groups presented statistically similar values after thermocycling. CONCLUSION: The bond strength of resin cement to lithium disilicate obtained after oxygen-based NTP was comparable with that obtained after conventional hydrofluoric acid treatment.


Assuntos
Colagem Dentária , Cimentos de Resina , Cerâmica , Porcelana Dentária , Propriedades de Superfície
7.
Nat Commun ; 11(1): 5208, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060581

RESUMO

Cryo-electron microscopy (cryoEM) is becoming the preferred method for resolving protein structures. Low signal-to-noise ratio (SNR) in cryoEM images reduces the confidence and throughput of structure determination during several steps of data processing, resulting in impediments such as missing particle orientations. Denoising cryoEM images can not only improve downstream analysis but also accelerate the time-consuming data collection process by allowing lower electron dose micrographs to be used for analysis. Here, we present Topaz-Denoise, a deep learning method for reliably and rapidly increasing the SNR of cryoEM images and cryoET tomograms. By training on a dataset composed of thousands of micrographs collected across a wide range of imaging conditions, we are able to learn models capturing the complexity of the cryoEM image formation process. The general model we present is able to denoise new datasets without additional training. Denoising with this model improves micrograph interpretability and allows us to solve 3D single particle structures of clustered protocadherin, an elongated particle with previously elusive views. We then show that low dose collection, enabled by Topaz-Denoise, improves downstream analysis in addition to reducing data collection time. We also present a general 3D denoising model for cryoET. Topaz-Denoise and pre-trained general models are now included in Topaz. We expect that Topaz-Denoise will be of broad utility to the cryoEM community for improving micrograph and tomogram interpretability and accelerating analysis.


Assuntos
Microscopia Crioeletrônica/métodos , Aprendizado de Máquina , Cimentos de Resina , Caderinas , Coleta de Dados , Tamanho da Partícula , Razão Sinal-Ruído
8.
J Contemp Dent Pract ; 21(7): 781-786, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33020363

RESUMO

AIM: This study aimed to assess the microleakage of a self-adhesive composite compared to conventional composites in class V cavities. MATERIALS AND METHODS: In this in vitro experimental study, standard class V cavities were prepared in the buccal surface of 204 extracted teeth and randomly divided into six groups for restoration with (A) Vertiseflow (Kerr) self-adhesive composite, (B) acid etching (Kerr) + Vertiseflow, (C) acid etching + Optibond FL (Kerr) + Vertiseflow, (D) Er,Cr:YSGG laser + Vertiseflow, (E) acid etching + Optibond FL + Premise Flowable (Kerr), and (F) acid etching + Optibond FL + Z250 (3M). The teeth in each group were then randomly divided into two subgroups of with and without thermocycling (10,000 cycles between 5°C and 55°C). The microleakage was then determined at the enamel and dentin margins under a stereomicroscope using the dye penetration method. Data were analyzed using the Kruskal-Wallis test (α = 0.05). RESULTS: No significant difference was noted in occlusal margin microleakage of no thermocycling groups, but acid etching + Vertiseflow showed the highest microleakage. At the gingival margin, the difference between acid etching + bonding agent + Z250 and laser + Vertiseflow was significant (p = 0.004). In thermocycling groups, the difference in the microleakage at the occlusal margin of Vertiseflow with that of acid etching + bonding agent + Premise (p = 0.002), acid etching + bonding agent + Vertiseflow (p = 0.009), and acid etching + bonding agent + Z250 (p = 0.037) groups was significant. The difference in the microleakage at the dentin margin was also significant among the groups (p < 0.05). The highest and the lowest microleakages were noted in laser + Vertiseflow and acid etching + bonding agent + Vertiseflow groups, respectively. CONCLUSION: Surface preparation with etching and adhesive application results in lower microleakage in class V cavities. But laser irradiation and the use of self-adhesive composite increase the microleakage. CLINICAL SIGNIFICANCE: It seems that self-adhesive composites cannot provide acceptable marginal integrity without any surface treatment.


Assuntos
Infiltração Dentária , Cimentos de Resina , Resinas Compostas , Cimentos Dentários , Restauração Dentária Permanente , Humanos
9.
Oper Dent ; 45(6): 664-676, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32997740

RESUMO

CLINICAL RELEVANCE: When a resin nanoceramic inlay is cemented using self-adhesive cement, a universal dentin adhesive can be applied to the prepared cavity. The application of the adhesive before self-adhesive cement placement provides similar or better interfacial adaptation than without the adhesive. SUMMARY: Purpose: The first objective of this study was to determine whether the luting material used for computer-aided design and computer-aided manufacture resin nanoceramic inlays affected interfacial adaptation. The second objective was to investigate whether application of a universal dentin adhesive before cementation affected interfacial adaptation. The final objective was to compare the inlay-side and dentin-side interfaces in the cement space.Methods and Materials: Seventy-four class I cavities were prepared on extracted human third molars. Cavities were optically scanned, and resin nanoceramic inlays were milled using Lava Ultimate blocks (3M ESPE). For the control groups, the fabricated inlays were cemented using Panavia V5 (Kuraray Noritake) or FujiCem 2 (GC). For the experimental groups, the teeth were randomly divided into groups I and II. Group I contained four subgroups using different luting materials; in all subgroups, the inlays were cemented and dual cured without pretreatment. Group II contained six subgroups in which inlays were cemented and dual cured after application of a universal dentin adhesive. After thermocycling, interfacial adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and statistically compared among groups.Results: Interfacial adaptation was different depending on the luting material used (p<0.05). After application of a universal adhesive, some subgroups showed improved interfacial adaptation (p<0.05). In the comparison of inlay-side and dentin-side interfaces, no difference was found in interfacial adaptation (p>0.05).Conclusions: Interfacial adaptation for resin nanoceramic inlays differed with luting material. For some self-adhesive cements, application of a universal adhesive before cementation improved interfacial adaptation.


Assuntos
Restaurações Intracoronárias , Tomografia de Coerência Óptica , Resinas Compostas , Desenho Assistido por Computador , Preparo da Cavidade Dentária , Porcelana Dentária , Humanos , Teste de Materiais , Cimentos de Resina
10.
Braz Dent J ; 31(4): 417-422, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32901719

RESUMO

The aim of this study was to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on bond strength of fiberglass posts in root canals obturated with different endodontic sealers. Seventy-eight mandibular premolars were obturated with three sealers (n=26): Endofill (END), AH Plus (AHP), and Endosequence BC Sealer (EBS). After preparation of the post space, two subgroups were formed according to the cementation of the posts (n=13): with EDC (EDC), and without EDC (control - CON). The specimens were submitted to a pull-out test, failure mode classification, and root canal surface evaluation by scanning electron microscopy after post displacement. Regarding the bond strength, a significant difference between the EDC and CON subgroups occurred only in the END (p=0.001). No difference was detected among the CON subgroups (p=0.339). However, among the EDC subgroups, AHP presented significantly higher values (END versus AHP: p=0.001; AHP versus EBS: p=0.016). Upon classification of failure modes, score 1 (≥ 50% of cement) was the most commonly observed, except for the END + EDC. Remains of endodontic sealers and resin cements were found in the cervical third, but without statistical difference (p=0.269), while in the middle third, difference occurred (p=0.004). In conclusion, EDC decreases bond strength when associated with END sealer, without changing the failure mode between the resin cement and fiberglass post. The best performance was observed when EDC was combined with AHP sealer.


Assuntos
Colagem Dentária , Técnica para Retentor Intrarradicular , Carbodi-Imidas , Cimentação , Cimentos de Resina
11.
Braz Dent J ; 31(4): 440-444, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32901722

RESUMO

Posterior build-ups are auxiliary devices to orthodontic treatment which are made with resin-based or glass ionomer composites. Their removal requires care to protect the tooth surface, therefore, pigmented materials are preferred for a better visualization. This study proposed a pigmentation experimental technique of a regular composite resin, evaluating the microshear bond strength test (µ-SBT) of this experimental pigmented resin and comparing with a blue-colored polyacid-modified composite resin, used for posterior buildups. Forty-eight buccal and lingual surfaces of human teeth were used and randomly divided into 4 groups (n=12). The groups were divided into: C (control), regular composite resin; P, regular composite resin pigmented; UBL, Ultra Band Lok™; OB, Ortho Bite™. The composites were bonded using a matrix to obtain microcylinders and prepared for each experimental groups. The samples were then stored in distilled water for 24h at 37°C followed by a µ-SBT. The types of bond failures were evaluated using a stereoscopic magnifying glass (10×). The data were analyzed by ANOVA with Fisher post hoc and Dunnett´s test. Means of µ-SBT± standard deviation (MPa) were: C (39.98a±13.0), P (40.09a± 14.3); UBL (33.26ab±8.6); OB (28.70b±5.5). The most prevalent type of failure was adhesive (80.4%). Further, was not observed a statistically significant correlation between the bond strength values and failure patterns. The pigmentation of a commercially available resin did not alter the µ-SBT and exhibited similar adhesiveness as a polyacid-modified composite resin.


Assuntos
Resinas Compostas , Colagem Dentária , Cimentos de Ionômeros de Vidro , Humanos , Teste de Materiais , Pigmentação , Cimentos de Resina
12.
Head Face Med ; 16(1): 20, 2020 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-32891153

RESUMO

INTRODUCTION: Bond failure during fixed orthodontic treatment is a frequently occurring problem. As bracket rebonding is associated with reduced shear bond strength, the aim of the present investigation is to analyse the effect of different innovative rebonding systems to identify optimised rebonding protocols for orthodontic patient care. METHODS: Metallic brackets were bonded to the frontal enamel surfaces of 240 bovine lower incisors embedded in resin bases. Teeth were randomly divided into two major experimental groups: in group 1 a hydrophilic primer (Assure™ PLUS) was compared to commonly used orthodontic adhesives (Transbond XT™, BrackFix®, Grengloo™) and a zero control. In group 2 different rebonding systems were analysed using a hydrophilic primer (Assure™ PLUS), a methyl methacrylate-consisting primer (Plastic Conditioner) and a conventional adhesive (Transbond XT™). All teeth were tested for shear bond strength according to the DIN-13990 standard, the Adhesive Remnant Index and enamel fracture rate. RESULTS: The hydrophilic primer enhanced shear bond strength at first bonding (Assure™ PLUS 20.29 ± 4.95 MPa vs. Transbond XT™ 18.45 ± 2.57 MPa; BrackFix® 17 ± 5.2 MPa; Grengloo™ 19.08 ± 3.19 MPa; Meron 8.7 ± 3.9 MPa) and second bonding (Assure™ PLUS 16.76 ± 3.71 MPa vs. Transbond XT™ 13.06 ± 3.19 MPa). Using Plastic Conditioner did not seem to improve shear bond strength at rebonding (13.57 ± 2.94). When enamel etching was left out, required shear bond strength could not be achieved (Plastic Conditioner + Assure™ PLUS 8.12 ± 3.34 MPa; Plastic Conditioner: 3.7 ± 1.95 MPa). Hydrophilic priming systems showed decreased ARI-scores (second bonding: 2.63) and increased enamel fracture rates (first bonding: 55%; second bonding 21,05%). CONCLUSIONS: Based on the present study we found that rebonding strength could be compensated by the use of hydrophilic priming systems. The additional use of a methyl methacrylate-consisting primer does not seem to enhance shear bond strength. No etching approaches resulted in non-sufficient bond strength.


Assuntos
Condicionamento Ácido do Dente , Colagem Dentária , Braquetes Ortodônticos , Animais , Bovinos , Cimentos Dentários , Análise do Estresse Dentário , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento
13.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 38(4): 376-379, 2020 Aug 01.
Artigo em Chinês | MEDLINE | ID: mdl-32865354

RESUMO

OBJECTIVE: This study aimed to compare the effects of water storage treatment and thermal cycling on the shear bond strength (SBS) of three self-adhesive dual-cure resin cements. METHODS: Six cubic zirconia specimens with side length of 2 cm were obtained by cutting and sintering. Three self-adhering dual-cure resin cements (i.e., Clearfil SAC, RelyX U200, and Multilink Speed) were selected. According to their bonding modes, they were divided into three groups: direct bonding group (direct coating with resin cement), adhesive group (applying universal adhesives and then coating with resin cement), and primer group (applying Z-Prime Plus and then coating with resin cement). According to experimental conditions, each group was divided into two subgroups: subgroup a (water storage at 37 ℃ for 24 h) and subgroup b (thermalcycling for 5 000 times). SBS data were analyzed by one-way ANOVA by using SPSS 19.0 software (P<0.05). The fractured zirconia surface was observed under a stereomicroscope. RESULTS: After water storage for 24 h, the SBS of the adhesive group and the primer group of the three resin cements was higher than that of the direct adhesive group (P<0.05), but the difference in SBS between the adhesive group and the primer group was not significant (P>0.05). After thermalcycling, the SBS of the three types of resin cements decreased (P<0.05); the SBS of the adhesive group was higher than that of the direct adhesive group and the primer group (P<0.05). Fracture mode analysis revealed that the type Ⅲ fracture mode evidently increased after the thermalcycling treatment compared with the water storage treatment. CONCLUSIONS: The universal adhesives and the primer can improve the SBS of self-adhesive dual-cure resin cement in water storage at 37 ℃ for 24 h. The universal adhesives had a better bonding durability than the zirconia primer.


Assuntos
Colagem Dentária , Cimentos de Resina , Cerâmica , Cimentos Dentários , Análise do Estresse Dentário , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície , Zircônio
14.
Braz Oral Res ; 34: e105, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32876118

RESUMO

The aim of this research was to evaluate the influence of MDP (10-methacryloyloxydecyl dihydrogen phosphate) concentration and application mode of experimental adhesives on microshear bond strength (µSBS) to dentin after storage in distilled water at 37°C for 24h and 6 months. Five experimental adhesives were prepared with: CQ, DABE, BHT, ethanol, HEMA, TEGDMA, Bis-EMA, UDMA, and Bis-GMA. Concentrations of 0 wt%, 3 wt%, 9 wt%, 12 wt% or 15 wt% of MDP were added to their composition. The adhesives were applied to flat dentin surfaces in etch-and-rinse or self-etching modes. Cylindrical molds filled with light-cured composite resin were placed above the dentin. The specimens were stored in distilled water at 37oC for 24h or 6 months and submitted to µSBS testing. The adhesives were also submitted to pH analysis. The data were analyzed by one-way ANOVA, three-way ANOVA and Tukey's test (α = 5%). All the adhesives used in the etch-and-rinse mode showed significantly higher bond strength than the adhesives applied in the self-etching approach. The 9 wt% adhesive showed the highest bond strength values, and 3 wt% was most stable after storage. A strong negative correlation between MDP concentration and pH was observed. It was concluded that the formulations with low concentrations of MDP (up to 9 wt%) showed better results for bond strength and bond strength degradation over time.


Assuntos
Colagem Dentária , Adesividade , Resinas Compostas , Cimentos Dentários , Dentina , Adesivos Dentinários , Teste de Materiais , Cimentos de Resina , Resistência à Tração
15.
Dental Press J Orthod ; 25(4): 59-67, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32965388

RESUMO

OBJECTIVE: To compare the effectiveness of the pretreatment with sandblasting and deproteinization with NaOCl on bond strength (SBS), in situ conversion degree (CD) of brackets in fluorotic enamel, and enamel etching pattern. METHODS: A total of 90 non-carious maxillary premolars were used. The teeth were then assigned to six experimental groups according to: enamel surface (sound and fluorotic enamel); surface treatment (Regular etch with 37% phosphoric acid [RE]; 5.2% sodium hypochlorite + phosphoric acid [NaOCl + RE]; sandblasting + phosphoric acid [sandblasting + RE]). After storage in distilled water (37°C/24h), the specimens were tested at 1 mm/min until failure (SBS). Enamel-resin cement interfaces were evaluated for CD using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a scanning electron microscope. Data from SBS and in situ CD values were analyzed using ANOVA two-away and Tukey test (α=0.05). The enamel etching pattern was evaluated only qualitatively. RESULTS: For sound enamel, RE showed the highest SBS values, when compared to NaOCl + RE and Sandblasting + RE groups (p< 0.01). Regarding CD, only NaOCl + RE significantly compromised the mean DC, in comparison with other groups (p= 0.002). For fluorotic enamel, the Sandblasting + RE group significantly increased the mean SBS values, in comparison with RE group (p= 0.01) and no significant change was observed for CD (p> 0.52). CONCLUSIONS: The application of NaOCl or sandblasting associated to phosphoric acid improved the SBS of the brackets in fluorotic enamel without compromising the CD of the resin cement, with improving of enamel interprismatic conditioning.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Condicionamento Ácido do Dente , Cimentos Dentários , Esmalte Dentário , Teste de Materiais , Ácidos Fosfóricos , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
16.
Int J Prosthodont ; 33(5): 536-545, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32956435

RESUMO

PURPOSE: To evaluate the shear bond strength (SBS) and color stability (ΔE) of four ceramic veneers (VITA VM 9; VITA VM 13; VITA VMK 95; and IPS e.max Ceram) following repair with three different self-adhesive composite resins (Fusio Liquid Dentin; Constic; and Vertise Flow) and BISCO Intraoral Repair Kit + Filtek Supreme (BC + FS). MATERIALS AND METHODS: A total of 96 specimens were prepared per ceramic material, and each ceramic group was divided into subgroups according to testing method (32 specimens for color stability analysis and 64 specimens for SBS testing). ΔE and SBS (SBS1 = non-aged, SBS2 = thermally aged) values of the repaired specimens were calculated. One specimen from each of the thermally aged groups was investigated under scanning electron microscopy (SEM). Two-way ANOVA was used to analyze the mean ΔE, SBS1, and SBS2 values. The differences between SBS1 and SBS2 values were analyzed using independent-samples t test. RESULTS: The lowest ΔE values were calculated for Constic (P ≤ .05). The SBS2 values among all groups were lower than the SBS1 values (P ≤ .05). The lowest SBS2 values were observed for Vertise Flow (2.3 ± 1.47 MPa) (P ≤ .05) and were below the acceptable limit of 5 MPa. CONCLUSION: All of the investigated repair materials in combination with the ceramic veneers exhibited ΔE values that were higher than the clinically acceptable limits. Thermal aging negatively affected the SBS values in all groups (P ≤ .05). All tested self-adhesive composite resins, with the exception of Vertise Flow, could be used instead of a repair kit with flowable composite resin, especially in noncooperative patients, for the purpose of repairing chipping fractures for VITA VM 9, VITA VM 13, and VITA VMK 95 (P > .05).


Assuntos
Colagem Dentária , Cimentos Dentários , Resinas Acrílicas , Cerâmica , Cor , Resinas Compostas , Porcelana Dentária , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
17.
Int J Prosthodont ; 33(5): 527-535, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32956434

RESUMO

PURPOSE: To establish the most effective cementation protocol for bonding zirconia crowns to Ti-Base CAD/CAM abutments in terms of abutment height, cement type, and surface pretreatment. MATERIALS AND METHODS: Zirconia crowns were designed to fit abutments of 2.5-mm (short) and 4.0-mm (tall) height. The retention of conventional resin cement with a universal adhesive (RelyX Ultimate, 3M ESPE) was compared to self-adhesive resin cement (RelyX U200, 3M ESPE) following different surface pretreatments (n = 10/group): (1) no treatment (NT); (2) Ti-Base abutment surface blasting with alumina particles (SB); (3) zirconia crown tribochemical surface blasting with silica-coated alumina particles (TBS); and (4) a combination of SB + TBS. Pull-out testing was performed in a universal testing machine. Data were statistically evaluated using a linear mixed model following least significant difference post hoc test. RESULTS: Pull-out data as a function of Ti-Base height demonstrated higher retention for tall compared to short abutments (P < .001). Ultimate outperformed U200 cement (data collapsed over height and pretreatment) (P < .001). Analysis of pretreatment depicted higher retention for SB + TBS, followed by SB, TBS, and NT (P < .04). The interaction between Ti-Base height and cement type highlighted the superior adhesive strength of Ultimate compared to U200 for both heights (P < .001). Irrespective of type of pretreatment, surface pretreatment improved the retention for U200 cement and short Ti-Base (P < .03 compared to NT). In contrast, higher retention was demonstrated for SB + TBS, followed by SB, TBS, and NT, for Ultimate cement combined with tall Ti-Base (P < .02) (data collapsed over height and cement, respectively). CONCLUSION: There was a direct relationship among Ti-Base height, micromechanical and/or chemical pretreatment, and conventional adhesive bonding in improving the retention of zirconia crowns.


Assuntos
Cimentação , Titânio , Desenho Assistido por Computador , Coroas , Dente Suporte , Análise do Estresse Dentário , Teste de Materiais , Cimentos de Resina , Zircônio
18.
Int J Prosthodont ; 33(5): 546-552, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32956436

RESUMO

PURPOSE: To evaluate the effect of cementation protocols on the bonding interface stability and pull-out forces of temporary implant-supported crowns bonded on a titanium base abutment (TiB) or on a temporary titanium abutment (TiA). MATERIALS AND METHODS: A total of 60 implants were restored with PMMA-based CAD/CAM crowns. Five groups (n = 12) were created: Group 1 = TiB/SRc: crown conditioned with MMA-based liquid (SR Connect, Ivoclar Vivadent); Group 2 = TiB/50Al-MB: crown airborne particle-abraded with 50-µm Al2O3 and silanized (Monobond Plus, Ivoclar Vivadent); Group 3 = TiB/30SiOAl-SRc: crown airborne particle-abraded with 30-µm silica-coated Al2O3 (CoJet, 3M ESPE) and conditioned with MMA-based liquid (SR Connect); Group 4 = TiB/30SiOAl-MB: crown airborne particle-abraded with 30- µm silica-coated Al2O3 (CoJet) and silanized (Monobond Plus); and Group 5 = TiA/TA-PMMA: crown manually enlarged, activated, and rebased with PMMA resin (Telio Lab, Ivoclar Vivadent). Specimens in the TiB groups were cemented using a resin cement (Multilink Hybrid Abutment, Ivoclar Vivadent). After aging (120,000 cycles, 49 N, 1.67 Hz, 5°C to 55°C, 120 seconds), bonding interface failure was analyzed (50x). Pull-out forces (N) (0.5 mm/minute) and modes of failure were registered. Chi-square and Kruskal-Wallis tests were used to analyze the data (α = .05). RESULTS: Bonding failure after aging varied from 0% (Group 5) to 100% (Groups 1, 2, and 4) (P < .001). Mean pull-out force ranged between 53.1 N (Group 1) and 1,146.5 N (Group 5). The pull-off forces were significantly greater for Group 5 (P < .05), followed by Group 3 (P < .05), whereas the differences among the remaining groups were not significant (P > .05). CONCLUSION: The cementation protocol had an effect on the bonding interface stability and pull-out forces of PMMA-based crowns bonded on a titanium base. Airborne particle abrasion of the crown internal surface and conditioning it with an MMA-based liquid may be recommended to improve retention of titanium base temporary restorations. Yet, for optimal outcomes, conventional temporary abutments might be preferred.


Assuntos
Implantes Dentários , Titânio , Desenho Assistido por Computador , Coroas , Dente Suporte , Análise do Estresse Dentário , Teste de Materiais , Cimentos de Resina , Zircônio
19.
J Am Dent Assoc ; 151(10): 796-797.e2, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32979959

RESUMO

BACKGROUND: Bonding crowns and bridges with resin cement can improve retention and reinforcement of the restoration. However, there is variation in the steps taken by different practitioners to achieve this goal. METHODS: The authors developed a survey on bonding dental crowns and bridges with resin cement and distributed it electronically to the American Dental Association Clinical Evaluators (ACE) Panel on May 22, 2020. The survey remained open for 2 weeks. Descriptive data analysis was conducted using SAS Version 9.4. RESULTS: A total of 326 panelists responded to the survey, and 86% of respondents who place crowns or bridges use resin cements for bonding. When placing a lithium disilicate restoration, an almost equal proportion of respondents etch it with hydrofluoric acid in their office or asked the laboratory to do it for them, and more than two-thirds use a silane primer before bonding. For zirconia restorations, 70% reported their restorations are sandblasted in the laboratory, and 39% use a primer containing 10-methacryloyloxydecyl dihydrogen phosphate. One-half of respondents clean their lithium disilicate or zirconia restorations with a cleaning solution. Resin cements used with a primer in the etch-and-rinse mode are the most widely used. The technique used to cure and clean excess resin cement varies among respondents. CONCLUSIONS: The types of resin cements used, tooth preparation, crown or bridge preparation, and bonding technique vary among this sample. PRACTICAL IMPLICATIONS: Although many dentists bond crowns and bridges on the basis of best practices, improvement in the process may be achieved by dentists communicating with their laboratory to confirm the steps performed there, ensuring an effective cleaning technique is used after try-in and verifying that the correct primer is used with their chosen restorative material.


Assuntos
Colagem Dentária , Cimentos de Resina , American Dental Association , Coroas , Cimentos Dentários , Materiais Dentários , Porcelana Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Propriedades de Superfície , Inquéritos e Questionários , Estados Unidos
20.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(8): 1165-1171, 2020 Aug 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895182

RESUMO

OBJECTIVE: To investigate the effect of orthodontic traction on the microstructure of dental enamel. METHODS: Forty-eight isolated premolars were randomly divided into 6 groups (n=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome. RESULTS: Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2. CONCLUSIONS: Orthodontic traction can cause changes in the microstructure of normal dental enamel.


Assuntos
Esmalte Dentário , Teste de Materiais , Braquetes Ortodônticos , Cimentos de Resina , Propriedades de Superfície , Tração
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