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1.
Int J Prosthodont ; 34(2): 221-228, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33882568

RESUMO

PURPOSE: To investigate whether high-level irradiance and short light exposure times with light-emitting diode (LED) curing units could provide bond strength comparable to halogen lights for ceramic laminate veneers (CLVs). MATERIALS AND METHODS: A total of 160 extracted human maxillary central incisors were prepared to receive CLVs (lithium disilicate) in shades A1 and A3.5. CLVs were luted with light-curing (LC) and dual-curing (DC) resin cements using four protocols: 3 seconds in extra power mode, 8 seconds in high power mode, or 10 seconds in standard mode with an LED unit, or 40 seconds with a conventional halogen light from all aspects (n = 10). Following thermal cycles, shear bond strength test was performed with a universal testing machine. Data were analyzed using one-way analysis of variance and post hoc Tukey test. Failure modes were classified under a stereomicroscope, and data were analyzed using Pearson chi-square test (P = .050). RESULTS: According to the intragroup comparison of different irradiation protocols, the mean shear bond strength of the A1-LC-10 group was found to be significantly higher than that of the A1-LChalogen group (P = .026). Shear bond strength values of the A1-LC-10 group and A3.5-LC-10 group were significantly higher than that of the A3.5-DC-10 group (P = .003). The A3.5-DC-3, A3.5-LC-3, and A1-DC-8 groups revealed the significantly most adhesive failures, and the A1-LC-8 group revealed the most mixed failures (P < .001). CONCLUSION: Both light and dark ceramic shades with LC cement combination responded the best to the standard mode of 10-second exposure time with LED application. However, with conventional halogen light application, the highest bond strength values were obtained with DC cement and light ceramic shade combination.


Assuntos
Luzes de Cura Dentária , Colagem Dentária , Cerâmica , Análise do Estresse Dentário , Cimentos de Ionômeros de Vidro , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
2.
Braz Dent J ; 32(1): 78-84, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33914006

RESUMO

The objective of this study was to evaluate the effect of the exposure reciprocity law of a multi-wave light-emitting diode (LED) on the light transmittance (LT), depth of cure (DOC) and degree of conversion in-depth (DC) of a bulk fill composite. A bulk fill composite (EvoCeram® bulk fill, Ivoclar Vivadent) was photoactivated using the multi-wave LED (VALO™ Cordless, Ultradent). The LED was previously characterized using a spectrophotometer to standardize the time of exposure when using the Standard or Xtra-Power modes with the same radiant exposure of 20J/cm2. LT was evaluated through samples of the bulk fill composite every millimeter till 4 mm in-depth. DOC was evaluated according to the ISO 4049. DC of the central longitudinal cross-section from each sample of the DOC test was mapped using FT-NIR microscopy. Data were statistically analyzed according to the experimental design (α=0.05; ß=0.2). The radiant exposure in the violet wavelength range for Standard and Xtra-Power was 4.5 and 5.0 J/cm2, respectively; for the blue wavelength range the radiant exposure for Standard and Xtra-Power was 15.5 and 15.0 J/cm2, respectively. There was no statistical difference in the DOC using Standard or Xtra-Power light-curing modes, but the DOC was lower than the claimed by the manufacturer (4 mm). The DC was not significantly affected by the light-curing mode up to 4 mm in depth (p>0.05). According to exposure reciprocity law, the reduction in exposure time using the same radiant exposure did not affect the depth of cure of the bulk fill composite.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , Cor , Dureza , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Polimerização , Propriedades de Superfície
3.
J Adhes Dent ; 23(2): 121-131, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33825426

RESUMO

PURPOSE: This study evaluated the effect of the design of the light-curing unit (LCU) and mouth opening on the properties of bulk-fill resin-based composites (RBCs). MATERIALS AND METHODS: Eighty molars received a mesio-occlusal-distal preparation and were restored using two different bulk-fill RBCs, Opus Bulk Fill APS (FGM) and Filtek Bulk Fill One (3M Oral Care), using two different designs of LCU, straight (Valo Cordless [Ultradent]) and angled (Radii-Cal [SDI]). Two mouth openings of 25 and 45 mm at the incisors were used. Forty samples were sectioned mesiodistally. One half was immersed in tetrahydrofuran to examine the effect of the solvent on the RBCs (SE), and the other half to measure the degree of conversion (DC) in proximal and occlusal boxes using Fourier Transform Infrared spectroscopy. The other 40 samples were subjected to thermomechanical fatigue and immersed in silver nitrate to examine the gingival margin integrity (GMI) using SEM. The irradiance (mW/cm2) and emission spectrum (mW/cm2/nm) from the LCUs were measured using a MARC Resin Calibrator (BlueLight Analytics). DC data were analyzed by 3-way ANOVA and Tukey's test; SE and GMI were analyzed by an ANOVA on Ranks and Dunn test (α = 0.05). RESULTS: The DC values were similar in the occlusal and proximal boxes when using Valo Cordless, irrespective of RBC and the mouth opening used. Lower DC values were measured in proximal boxes when using Radii-Cal. The mouth opening had a greater effect on the irradiance delivered by Radii-Cal. Radii-Cal with 25-mm mouth opening had greater SE and GMI values, whereas the SE and GMI values obtained with Valo Cordless were unaffected by mouth opening. CONCLUSION: The choice of LCU did not influence the properties of tested bulk-fill RBCs when the 45-mm mouth opening was used. However, when using the 25-mm mouth opening, the choice of LCU did influence the properties of the RBCs.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Resinas Compostas , Teste de Materiais , Dente Molar , Polimerização , Propriedades de Superfície
4.
Pediatr Dent ; 43(1): 44-49, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33662250

RESUMO

Purpose: To determine the effect of a dental curing light on the penetration depth of silver diamine fluoride (SDF), dentin hardness, and silver and fluoride ion precipitation into cavitated carious lesions. Methods: SDF was applied on 16 primary incisors extracted due to caries extending into dentin. Teeth were divided into two groups: (1) control group, was not light-cured; and (2) test group, was light-cured. A scanning electron microscope, and OmniMet software were used to measure penetration depth, dentin hardness, and ion precipitation. Wilcoxon's ranksum test was used for statistical analysis. Results: All samples in both groups showed SDF penetration beyond the carious lesion and into sound dentin. The penetration depth into sound dentin was 70 µm further without the dental curing light it (P<0.001). Silver precipitation in infected dentin with the dental curing light was approximately 2.6 times greater than without it (P=0.02). Dentin hardness of infected dentin was 26 percent more with the dental curing light (P=0.04). Conclusions: Applying a dental curing light during silver diamine fluoride treatment of carious lesions induces more silver ion precipitation in infected dentin, increases its hardness, and, perhaps because more silver stays in the infected dentin, less SDF penetrates into sound dentin.


Assuntos
Luzes de Cura Dentária , Cárie Dentária , Cárie Dentária/terapia , Dentina , Fluoretos Tópicos , Humanos , Incisivo , Cura Luminosa de Adesivos Dentários , Compostos de Amônio Quaternário , Compostos de Prata
5.
Am J Dent ; 34(1): 44-48, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33544988

RESUMO

PURPOSE: To evaluate the effect of light cure, as well as various dentin surface treatment approaches, on the penetration depth of silver precipitating from 38% silver diamine fluoride into primary dentin tubules. METHODS: The occlusal dentin surfaces of 42 non-carious primary molars were exposed and then sectioned into halves bucco-lingually. The halves from each tooth pair were randomly split in two mega-groups, and each mega-group was divided randomly as follows into six experimental groups: prepared by either carbide bur (G1, G2), ceramic bur (G3, G4), or erbium laser (G5, G6). SDF was then applied to all prepared surfaces, and finally even-numbered groups (G2, G4, G6) were light cured. One mega-group was assigned to quantitative evaluation of silver penetration depth along the axial wall, and the other mega-group was reserved for qualitative observation of relative silver distribution on the occlusal surface, both via scanning electron microscope. RESULTS: No significant difference was observed in silver penetration depth between light cure and non-light cure groups (P= 0.8908). There was a statistically significant association between tooth preparation method and depth of silver penetration (P< 0.000001); laser-treated groups had significantly deeper silver penetration (1,148.9 µm G5, 1160.4 µm G6) than carbide bur (P< 0.05; 184.7 µm G1, 301.8 µm G2) or ceramic bur (P< 0.05; 184.1 µm G3, 131.0 µm G4) groups. A significant difference (P< 0.05) was noted in percentage occlusal surface coverage of particles between laser (51.4% G5, 35.8% G6) and carbide groups (21.1% G1, 19.3% G2). Light cure had no significant effect on the depth of silver penetration from 38% SDF in the dentin of primary teeth. Laser preparation resulted in deeper silver penetration than carbide or ceramic bur. CLINICAL SIGNIFICANCE: Exposure of 38% silver diamine fluoride-treated dentin to light cure did not affect the depth of penetration of silver particles into the dentin tubules of primary teeth. Rather, tooth preparation approaches that reduce the smear layer, like laser ablation, resulted in the deepest penetration of silver into the tubules. Clinical application of these findings will depend on scenario and treatment aim.


Assuntos
Luzes de Cura Dentária , Dentina , Fluoretos Tópicos , Cura Luminosa de Adesivos Dentários , Microscopia Eletrônica de Varredura , Compostos de Amônio Quaternário , Compostos de Prata , Dente Decíduo
7.
J Dent ; 105: 103568, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33385531

RESUMO

OBJECTIVE: This study correlates the mechanical and biological response of commercially available resin-based composites (RBCs) to clinically relevant light-curing conditions. METHODS: Two RBCs (Venus and Venus Pearl; Kulzer) that use different monomer and photo-initiator systems, but have a similar filler volume and shade, were exposed to either just blue light, or violet and blue light from two different LCUs (Translux Wave and Translux 2Wave; Kulzer). Distance and exposure times were adjusted so that both LCUs delivered 5 similar levels of radiant exposures (RE) between 1.5 J/cm²-25 J/cm² in the blue wavelength range. Thus, the violet light was additional light. The top and bottom of 2-mm thick specimens were subjected to a depth-sensing indentation test (Martens hardness/HM, Vickers hardness/HV, indentation modulus/YHU, mechanical work/Wtotal, plastic deformation work/Wplas, creep/Cr). The viability of human gingival fibroblasts was assessed after three days of exposure to RBC eluates. One and multiple-way analysis of variance (ANOVA), the Tukey honestly significant difference (HSD) post-hoc tests (α = 0.05), t-test and a Spearman correlation analysis were used. RESULTS: As the RE increased, the mechanical properties increased at a greater rate at the top compared to the bottom of the RBCs. Values measured at the bottom of 2-mm increments approached the values measured at the top only when RE > 25 J/cm² of blue light was delivered. Toxicity decreased with RE and elution cycles and was lower for Venus Pearl. Within one RE level, addition of violet light resulted in significantly improved properties (in 131 out of 150 comparisons, p < 0.05). This effect was stronger for Venus Pearl. There was a good correlation between mechanical and biological parameters. This correlation decreased as the number of eluates increased. CLINICAL SIGNIFICANCE: The mechanical and biological response to variation in RE is interrelated. The addition of violet light has a positive effect, particularly at low RE.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , Materiais Dentários , Dureza , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Polimerização , Propriedades de Superfície
8.
Dent Mater ; 37(3): 382-390, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33468405

RESUMO

OBJECTIVES: The two-component Camphorquinone (CQ)/aromatic amine system is well-established and clearly corresponds to the reference system used in all photopolymerizable dental adhesives and composites. However, this CQ/amine system still suffers from the presence of aromatic amines that can be referenced as toxic. Therefore, the aim of this work is to develop amine-free photoinitiating systems (PISs) for the polymerization of a representative dental methacrylate resins upon blue light irradiation. The proposed strategy is based on the in-silico design (by molecular modelling) of new hydrogen donors (amine-free) bearing a copolymerizable moiety (methacrylate functionality) to ensure their low migration/leaching properties from the synthesized polymer. The new proposed PISs are compared to the well-established CQ/amine system for the polymerization of different methacrylate blends upon exposure to a commercial blue dental LED centered at 477 nm. METHODS: Molecular orbitals calculations are used to design new hydrogen donors exhibiting low C-H bond dissociation energies. Based on this in-silico design, the syntheses of new co-initiators are reported here for the first time. Real-time FTIR experiments are used to monitor the photopolymerization profiles. Color indexes measurements were also carried out to investigate the bleaching properties of the new proposed systems. RESULTS: Three new co-initiators are proposed as alternatives to aromatic amines in dental materials in combination with camphorquinone. The performances of the new proposed amine-free PISs for the photopolymerization of thick (1.4 mm) samples of methacrylate upon exposure to a blue dental LED under air are excellent. Similar or better polymerization performances are obtained with the new proposed amine-free systems compared to those reached with the CQ/amine reference. Excellent bleaching properties are also found. The involved chemical mechanisms are investigated through molecular orbitals calculations.


Assuntos
Aminas , Hidrogênio , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Materiais Dentários , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Metacrilatos , Polimerização
9.
Oper Dent ; 46(1): 63-74, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33351938

RESUMO

CLINICAL RELEVANCE: The use of multipeak LED light-curing guarantees efficiency on light activation of Ivocerin-containing light-cured resin cement.


Assuntos
Luzes de Cura Dentária , Cimentos de Resina , Cura Luminosa de Adesivos Dentários , Teste de Materiais
10.
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
11.
Acta Odontol Latinoam ; 33(2): 82-89, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32920609

RESUMO

The aim of this study was to evaluate the degree of conversion, cytotoxicity, solubility and pH of photopolymerizable calciumbased cements submitted to preheating. The degree of conversion was analyzed by Fourier transform infrared, cytotoxicity by the MTT test and solubility through loss of mass. The data were subjected to statistical tests (ANOVA / Tukey's, p<0.05). The photopolymerizable materials showed a low degree of conversion, regardless of preheating. All materials caused a reduction in cell viability at 24 hours and 7 days, with the Dycal (control) being more cytotoxic. Heat had a positive effect on Biocal at 7 days. Dycal is the most soluble material. Heat had no effect on the solubility or pH of the polymerizable materials. It is concluded that photopolymerizable calcium-based cements have a low degree of conversion and are soluble, which results in mild to moderate cytotoxicity.


Assuntos
Hidróxido de Cálcio/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Cimentos Dentários/química , Agentes de Capeamento da Polpa Dentária e Pulpectomia/toxicidade , Cálcio , Hidróxido de Cálcio/química , Cimentos Dentários/toxicidade , Capeamento da Polpa Dentária , Humanos , Concentração de Íons de Hidrogênio , Cura Luminosa de Adesivos Dentários , Processos Fotoquímicos , Polimerização , Agentes de Capeamento da Polpa Dentária e Pulpectomia/química
12.
J Appl Oral Sci ; 28: e20190753, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32638829

RESUMO

Objectives To compare the microtensile bond strength (µTBS) and depth of cure (DOC) of bulk-fill composites cured by monowave (MW) and polywave (PW) LED units using different curing times. Methodology Three composites were tested: Tetric EvoCeram Bulk Fill (TBF), Filtek Bulk Fill (FBF), and Tetric EvoCeram (T; control). Flat dentin surfaces treated with adhesive (AdheSE Universal®, Ivoclar Vivadent) were bonded with 4 mm cylindrical samples of each bulk-fill composite material (n=6) and cured with monowave (Satelec) or polywave (Bluephase Style) curing units for 10 or 20 seconds. After 24 hours, teeth were sectioned into individual 0.9 mm2 beams and tested for µTBS. Failure modes were analysed. Moreover, the DOC scrape test (IOS 4090) was completed (n=5) following the same curing protocols. Two-way ANOVA (a=0.05) was performed, isolating light-curing units. Results For samples cured with the MW light-curing unit, no significant effects were observed in the µTBS results between any of the resin composite brands and the curing times. Conversely, when resins were cured with a PW light unit, a significant effect was observed for TBF resin. In general, bulk-fill composites presented greater DOC and longer curing time resulted in higher DOC for all composites. Conclusion The µTBS of the composites to dentin was not affected by the curing mode of the resins, except for TBF cured with PW light unit. Bulk-fill composites exhibit greater DOC than conventional resin-based composites.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Resinas Compostas , Materiais Dentários , Dentina , Teste de Materiais , Polimerização
13.
Dent Mater ; 36(4): 570-579, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32173087

RESUMO

OBJECTIVE: This study evaluates critical material properties resulting from ultra-fast (3 s) photo-polymerization at high radiant emittance of a pre-production, novel bulk-fill resin-based composite (RBC) modified for reversible addition-fragmentation chain transfer (RAFT) polymerization. METHODS: The output characteristics of the associated light curing unit (LCU) were measured on a laboratory-grade spectrometer. Real-time Fourier Transform Infrared Spectroscopy (FTIR) and mechanical investigations (depth-sensing indentation with a linear and spatial distribution of the measured properties, and three-point bend tests) were performed using, as reference material, an established bulk-fill RBC of comparable chemical composition. Micro-mechanical properties were mapped to quantify material tolerance to sub-optimal curing conditions (exposure distance of 5 mm and an angulation of the LCU of 20° and 30°) vs. ideal curing conditions (exposure distance of 0 mm and no angulation), with 3 s polymerization. Weibull statistics, one- and multiple-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) post hoc-test (α = 0.05) were used for data comparison. RESULTS: The change in cure mechanism to RAFT polymerisation gave slightly faster initial polymerisation kinetics, but DC measured 300 s post irradiation was similar, irrespective of material, curing depth or polymerisation condition. Slightly better polymerisation, in layers thicker than 4-mm, was identified in the RAFT polymerised RBC. However, slightly lower flexural modulus and hardness, up to 1.5-mm subsurface, were related to the ca. one wt.% lower inorganic filler content. SIGNIFICANCE: RAFT polymerisation induced comparable properties to a RBC cured via free radical polymerisation of comparable chemical composition. The RAFT polymerised RBC with high irradiance for 3 s was equivalent to 10 s of moderate irradiance. However, the clinical tolerance for 3 s irradiance should be limited to an exposure distance of 5-mm and angulation of the LCU should be avoided. If this is not possible, an additional 3 s polymerisation is recommended.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Resinas Compostas , Materiais Dentários , Dureza , Teste de Materiais , Polimerização , Propriedades de Superfície
14.
J Dent Educ ; 84(6): 652-659, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32064625

RESUMO

BACKGROUND: Light-curing is a crucial step during the application of composite resin restorations. Composite's success depends on delivering enough light energy to the resin to achieve adequate polymerization. However, dentists are not recognizing the importance of proper light-curing technique. OBJECTIVES: To measure light energy delivered to simulated restorations by preclinical dental students and dentists in internship year. To evaluate the effect of experience and training on the clinician's ability to light-cure composite restorations. METHODS: A group of 50 preclinical dental students and a group of 50 internship dentists light-cured for 10 seconds, a simulated class III and class I restorations positioned in a patient simulator (MARC-Patient Simulator [BlueLight Analytics Inc., Canada]) that measured the irradiance and energy delivered by the curing light. Then participants received individualized training on optimizing their light-curing technique. They were retested after the training. Statistical analysis was done with two-way ANOVA and Tukey's test. RESULTS: Participants delivered an average of 60% more energy after the instructions, which is a significant improvement (P < 0.05). The number of participants that failed to deliver the minimum amount of energy (6 J/cm²) decreased significantly from 37.5% to 2.5%. There was a significant difference in the amount of energy delivered by the Preclinical and Internship groups (P < 0.05). CONCLUSION: Initially, many participants were not using the curing light properly. Light-curing technique improved with training and using a patient simulator. Experience can enhance the operator's ability to light-cure composite restorations. However, a training session can improve light-curing performance more than years of experience.


Assuntos
Luzes de Cura Dentária , Restauração Dentária Permanente , Canadá , Resinas Compostas , Odontólogos , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Papel Profissional
15.
Oper Dent ; 45(3): E141-E155, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32053458

RESUMO

OBJECTIVES: This study examined the influence of different light-curing units (LCUs) and exposure times on the microhardness across bulk-fill resin-based composite (RBC) restorations in a molar tooth. METHODS AND MATERIALS: Tip diameter, radiant power, radiant exitance, emission spectra, and light beam profile were measured on two single-emission-peak LCUs (Celalux 3 and DeepCure-S) and two multiple-peak LCUs (Bluephase 20i and Valo Grand). A mold was made using a human molar that had a 12-mm mesial-distal length, a 2.5-mm deep occlusal box, and two 4.5-mm deep proximal boxes. Two bulk-fill RBCs (Filtek Bulk Fill Posterior and Tetric EvoCeram Bulk Fill) were photoactivated for 10 seconds and for 20 seconds, with the light guide positioned at the center of the occlusal surface. Microhardness was then measured across the transverse surface of the restorations. The light that reached the bottom of the proximal boxes was examined. Data were statistically analyzed with the Student t-test, two-way analysis of variance, and the Tukey post hoc test (α=0.05). RESULTS: The four LCUs were different regarding all the tested characteristics. Even when using LCUs with wide tips and a homogeneous beam profile, there were significant differences in the microhardness results obtained at the central and proximal regions of the RBCs (p<0.05). LCUs with wider tips used for 20 seconds produced higher microhardness values (p<0.05). The multiple-peak LCUs produced greater hardness values in Tetric EvoCeram Bulk Fill than did the single-emission-peak LCUs (Celalux 3 and DeepCure-S). Results for the light measured at the bottom of proximal boxes showed that little light reached these regions when the light tip was positioned at the center of restorations. CONCLUSIONS: Curing lights with wide tips, homogeneous light beam profiles, and longer exposure times are preferred when light-curing large MOD restorations. Light curing from more than one position may be required for adequate photopolymerization.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Resinas Compostas , Materiais Dentários , Dureza , Humanos , Teste de Materiais , Dente Molar , Polimerização , Propriedades de Superfície
16.
J Biol Regul Homeost Agents ; 34(1 Suppl. 1): 39-47, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32064834

RESUMO

The aim of this study is to evaluate the micro hardness Vickers of a composite micro hybrid polymerized under constant pressure. Twelve experimental samples were made equally divided into two groups: an experimental group and a control. Enamel plus HRi (Micerium) microbiotic composite resin, UD3 colour, was inserted into a syringe heater (ENA HEAT Composite Heating Conditioner) so that the material could be brought to a temperature of 39°C. A defined amount of composite resin is taken from the syringe with a Heidemann spatula and placed between two slides, previously cleaned with 90 ° alcohol. The samples are then inserted one at a time into a special device for constant pressure application. Vickers hardness measurements were made on the top of surfaces. The mean value of the samples belonging to the experimental group is 56.81 ± 0.71. The mean value of the control samples is 52.02 ± 2. The results obtained allow us to state that applying a constant pressure during the cementation phase of indirect adhesive restorations allows to obtain better mechanical characteristics of the composite used as a cementing agent.


Assuntos
Resinas Compostas , Materiais Dentários , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Dureza , Pressão , Propriedades de Superfície
17.
Oper Dent ; 45(5): 496-505, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32101499

RESUMO

CLINICAL RELEVANCE: Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units. SUMMARY: Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes.Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro-computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS.Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes.Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Dente Molar , Polimerização , Resistência ao Cisalhamento , Microtomografia por Raio-X
18.
Rev. bras. odontol ; 77(1): 1-5, jan. 2020. ilus, tab
Artigo em Inglês | LILACS | ID: biblio-1117693

RESUMO

Objetivo: este estudo teve como objetivo comparar a resistência de união à dentina de um material à base de silicato de cálcio fotopolimerizável modificado por resina (TheraCal LC®; Bisco, Schaumburg, IL, EUA) com MTA branco (WMTA®; Angelus, Londrina, PR, Brasil). Materiais e Métodos: dezesseis incisivos superiores e caninos humanos foram selecionados e três discos de 1 mm foram obtidos a partir do terço médio de cada raiz. Na superfície coronal de cada disco, dois furos de 1,2 mm de largura foram perfurados na dentina. Em seguida, os buracos artificiais foram preenchidos com um dos materiais testados: WMTA® e TheraCal LC®. As fatias dentárias preenchidas foram armazenadas em uma solução salina tamponada com fosfato (PBS) (pH 7,2) por 7 dias a 37°C. Depois disso, a avaliação do push-out foi realizada com uma ponta do êmbolo de 1,0 mm. A carga foi aplicada a uma velocidade de 0,5 mm / min até o deslocamento do selador. Os resultados foram expressos em MPa. O teste U de Mann-Whitney foi aplicado para classificar os materiais quanto à resistência adesiva à dentina. O nível de significância foi estabelecido em = 5%. Resultados: todas as amostras apresentaram resultados de resistência de união à dentina mensuráveis e não ocorreram falhas prematuras. O TheraCal LC® demonstrou valores superiores de resistência de união à dentina quando comparado ao WMTA® (P<0,0001). Conclusões: existe uma vantagem do TheraCal LC® sobre o WMTA® no que diz respeito à resistência da união ao empurrar e, portanto, pode ser considerado um material reparador promissor e inovador


Objective: this study aimed to compare the dentin bond strength of a resin-modified light-curable calcium-silicate-based material (TheraCal LC®; Bisco, Schaumburg, IL, USA) with White MTA (WMTA®; Angelus, Londrina, PR, Brazil). Materials and Methods: sixteen human maxillary incisors and canines were selected and three 1-mm-discs were obtained from the middle third of each root. On the coronal surface of each disc, two 1.2-mm-wide-holes were drilled through the dentin. Then, artificial holes were filled with one of the tested materials: WMTA® and TheraCal LC®. The filled dental slices were stored in a phosphate-buffered saline (PBS) solution (pH 7.2) for 7 days at 37°C. After that, push-out assessment was performed with a 1.0-mm-plunger-tip. Load was applied at a crosshead speed of 0.5 mm/min until sealer displacement. The results were expressed in MPa. Mann-Whitney U test was applied to rank materials regarding dentin push-out bond strength. Significance level was set at a = 5%. Results: All specimens showed measurable results and no premature failure occurred. TheraCal LC® demonstrated superior push-out bond strength values to dentin when compared to WMTA® (P<0.0001). Conclusions: there is advantage of TheraCal LC® over WMTA® as regards to the push-out bond strength and, therefore it may be taken as a promising and innovative reparative material


Assuntos
Materiais Restauradores do Canal Radicular , Obturação do Canal Radicular , Tratamento do Canal Radicular , Cimento de Silicato , Materiais Dentários , Endodontia , Cura Luminosa de Adesivos Dentários
19.
Oper Dent ; 45(3): 327-338, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31794346

RESUMO

This study evaluated the effect of light curing unit (LCU) guide type (regular or homogenizing) on top and bottom microhardness of conventional and bulk-fill resin-based composites (RBCs). A polywave light-emitting-diode (LED) LCU (Bluephase Style, Ivoclar Vivadent AG) was used with two different light guides: a regular tip (RT, 935 mW/cm2 emittance) and a homogenizer tip (HT, 851 mW/cm2 emittance). Two conventional RBCs (Herculite Ultra [HER], Kerr Corp; Tetric EvoCeram [TEC], Ivoclar Vivadent AG) and two bulk-fill RBCs (SonicFill [SOF], Kerr Corp; Tetric EvoCeram Bulk Fill [TBF], Ivoclar Vivadent AG) were tested. Disc-shaped samples (10 mm Ø), 2-mm thick for conventional composites and 4-mm thick for bulk-fill composites were prepared. Samples were light cured according to manufacturer-recommended times. Knoop microhardness values (KHN) were obtained on the top and bottom surfaces of each specimen at locations correlated with the output of the three LED chips emitting blue (456 nm) or violet light (409 nm). Beam profile analysis using both light guides was also performed. Microhardness of each composite was analyzed using three-way analysis of variance and Tukey honestly significant difference post hoc test (α=0.05). Beam profile images showed better light distribution across the surface of the HT light guide. Use of the HT decreased KHN of HER at the locations of the blue LED chips at bottom of the sample but had no effect on the top surface. For TEC, use of HT increased KHN of all three LED locations at the top surface. Use of the HT increased KHN of SOF at locations corresponding to one of the blue and the violet LED chips at the bottom surface. For TBF, HT increased KHN at all top surface locations. All RBCs showed higher mean KHN at the top compared with the bottom surfaces. In general, all composites presented a higher KHN at the blue LED areas regardless of the surface or the tip used. Results suggest that the homogenizer light guide resulted in significantly increased microhardness at the top, in composite resins containing alternative photoinitiators; however, that effect was not observed at the bottom surfaces.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Resinas Compostas , Materiais Dentários , Dureza , Teste de Materiais , Polimerização , Propriedades de Superfície
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