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1.
Clin Oral Investig ; 2021 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-34826031

RESUMO

OBJECTIVES: To evaluate the biaxial flexural strength (BFS), flexural modulus (BFM), and Knoop microhardness (KHN) of incremental and bulk-filled resin-based composites (RBCs) using extended curing exposure times. MATERIALS AND METHODS: Disc specimens (n = 8; 6-mm diameter) were fabricated using three stacked molds (0.5-mm thick for the top and bottom molds, and a 1-mm-thick center mold for the conventional and 3-mm thick for the bulk-fill RBCs). Conventional (Tetric EvoCeram/TCE and Filtek Z250/FIZ) and bulk-fill RBCs (Tetric EvoCeram Bulk Fill/TBF and Filtek One Bulk Fill Restorative/FOB) were evaluated. The stacked RBC-filled molds were light-cured for (1) the manufacturer-recommended exposure (MRE) duration; (2) 50%, and (3) 100% extension of the MRE. The BFS, BFM, and KHN of the top and bottom discs were measured. BFS and BFM were analyzed by three-way ANOVA (material*curing time*depth) and Tukey's post hoc (α = 0.05). KHN was analyzed by two-way ANOVA (curing time*depth) and Tukey's post hoc (α = 0.05). RESULTS: Extending the exposure duration did not change the BFS and BFM on the top of the RBCs, but the BFS and KHN increased at the bottom of bulk-fill RBCs. For the conventional RBCs, TCE showed the highest increase on BFS at the bottom, going from 53.6 MPa at T1 to 69.9 at T3. Among the bulk-fill RBCs, FOB presented the highest increase on the bottom BFS (T1: 101.0 ± 19.9 MPa, T3: 147.6 ± 12.9 MPa). For all RBCs and exposure times, BFS and KHN were lower at the bottom. Only FIZ and FOB reached a bottom-to-top hardness ratio of 80%, at T3 and T2. CONCLUSION: A significant increase on the BFS and KHN on the bottom of bulk-fill RBCs can be observed when the time of exposure to the curing light is double the MRE. However, extended exposure does not eliminate differences on the BFS and KHN between the shallow and deep regions of RBCs. TCE and TBF failed to reach an acceptable B/T hardness ratio at all evaluated exposure times. CLINICAL RELEVANCE: Mechanical properties of RBCs can be affected by insufficient polymerization, specially at deeper regions of the increment. Therefore, clinicians should consider applying twice the MRE to curing-light to polymerize the maximal increment thickness of bulk-fill RBCs.

2.
J Esthet Restor Dent ; 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34569699

RESUMO

OBJECTIVE: To evaluate the influence of shades of a multilayered zirconia on light transmission, resin cement degree of conversion, and shear bond strength of resin cement. MATERIALS AND METHODS: The light transmission through opaque (OPQ) and translucent (TNS) regions of Katana UTML zirconia (Kuraray Noritake Dental) were evaluated for using a spectroradiometer (n = 5). Degree of conversion of dual-cure resin cement (Panavia V5, Kuraray Noritake Dental) was measured after light-activation through OPQ or TNS regions and direct exposure. Composition of the zirconia was analyzed with energy dispersive x-ray spectroscopy (EDS). Shear bond strength (SBS) was evaluated on the OPQ and TNS regions after 24 h and 1 year from specimen preparation (n = 15). RESULTS: The OPQ region produced higher irradiance loss (95.1%) than TNS one (92.9%), and lower degree of conversion (52.4%) than TNS (71.2%) at 24 h post-light activation. EDS analysis did not show differences on the microstructure of the OPQ and TNS regions. There were no significant differences on the SBS between zirconia regions. For both zirconia regions, a significant reduction on the SBS occurred after aging, being 31.7% for OPQ and 38% for TNS. CONCLUSION: Both OPQ and TNS regions affected the light transmission through the multilayered zirconia. The OPQ region yielded the highest light attenuation and the lowest degree of conversion of resin cement. Different regions of the zirconia did not influence the SBS. Clinical significance Although opaque and translucent regions of the multilayered zirconia reduced the light transmission from LED curing unit and the degree of conversion of resin cement, the regions did not affect the resin cement adhesion.

3.
J Esthet Restor Dent ; 33(4): 628-635, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33675162

RESUMO

BACKGROUND: Bulk-fill materials can facilitate the restorative procedure mainly for deep and wide posterior cavities. The purpose of this study was to evaluate flexural strength (biaxial flexural strength [BFS]) and microhardness (Knoop microhardness [KHN]) at different depths of bulk-fill materials. METHODS: Five bulk-fill materials were tested: two light-curable composite resins, one dual-cure composite, one bioactive restorative, and a high-viscosity glass ionomer. A conventional composite was used as control. BFS and KHN were tested at different depths. Data was analyzed by two- and one-way ANOVAs, respectively and Tukey's post-hoc (α=0.05). RESULTS: The high-viscosity glass ionomer material presented the lowest BFS at all depths. KHN for the two light-curable and the dual-cure bulk-fill resin composites was reduced following an increase in restoration depth, while the conventional composite, the bioactive material, and the high-viscosity glass ionomer were not affected. CONCLUSION: There are differences in the properties of the tested materials at 4 mm depth, showing that the studied properties of some materials vary according to the cavity depth, although the results are material dependent. CLINICAL SIGNIFICANCE: Mechanical properties of light-cured, bulk-fill materials may be affected by inadequate polymerization. Clinicians should consider complementary strategies to achieve adequate polymerization at high-increment depths.


Assuntos
Materiais Dentários , Resistência à Flexão , Resinas Compostas , Teste de Materiais , Polimerização
4.
Dent Mater ; 36(9): 1201-1213, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32576408

RESUMO

OBJECTIVE: To evaluate the influence of light emitted from two Polywave®, LED light-curing units (LCU) on in vivo pulp temperature (PT) rise and signs of acute inflammatory response in pulps of human premolar having deep Class V preparations. METHODS: Sixty intact, first premolars from 15 volunteers requiring extraction received infiltrative anesthesia. A sterile thermocouple probe was inserted within the pulp tissue through a minute occlusal pulp exposure in only 45 teeth (n = 9) to continuously monitor PT (°C). A deep buccal Class V preparation was created, and the surface was exposed to light from a commercial Polywave LCU (Bluephase 20i (20i), Ivoclar Vivadent) or from an experimental LCU (Exp) using the exposure modes (EM): 1s/Exp and 2s/Exp, 10s/20i, 20s/20i, and 60s/20i. Peak PT and PT rise values above baseline (ΔT) data were evaluated using a one-way ANOVA followed by Tukey's post-hoc test (α = 5%). Teeth used for histological and immunohistochemical analyses (n = 3) were extracted approximately 2 h after exposure to the LCU. RESULTS: No significant difference in peak PT and ΔT values was noted between 2s/Exp and 20s/20i groups, which both exhibited higher values than 1s/Exp and 10s/20i groups (p < 0.001). Dilated and congested blood vessels were seen after exposure to 1s/Exp, 2s/Exp, or 60s/20i EMs. The expression of IL-1ß and TNF-α tended to be more intense when higher irradiance was delivered. SIGNIFICANCE: Although higher irradiance delivered over a short exposure caused lower PT rise than 5.5 °C, such EMs should be used with caution, as they have more potential to harm the pulp tissue.


Assuntos
Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Dente Pré-Molar , Resinas Compostas , Polpa Dentária , Humanos , Temperatura
5.
Braz Dent J ; 30(4): 397-403, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31340231

RESUMO

This study measured and compared exitance irradiance and power of 4 commercial dental light-curing units (LCU) (Elipar S10, Elipar DeepCure-S, Corded VALO and Bluephase Style) using different types of radiometers. The devices used to analyze the LCU were classified as either handheld analog (Henry Schein, Spring, Demetron 100A, Demetron 100B and Demetron 200), handheld digital (Bluephase 1, Bluephase II, Coltolux, CureRite and Hilux), or laboratory instruments (Thermopile and Integrating Sphere). The laboratory instruments and the Bluephase II radiometer were also used to measure the LCU's power (mW). The LCU's were activated for 20 s (n=5). Data were analyzed using Kruskal-Wallis and Student-Newman-Keuls multiple comparison test (a=0.05). Among the LCU, the laboratory instruments presented different irradiance values, except for Corded VALO. The Coltolux and Hilux radiometers measured greater irradiance values compared to the laboratory instruments for the four LCUs tested. Within a given LCU, handheld analog units measured lower irradiance values, compared to handheld digital and laboratory instruments, except using the Spring radiometer for the Elipar S10 LCU. None of the handheld radiometers were able to measure similar irradiance values compared to laboratory instruments, except for Elipar S10 when comparing Bluephase 1 and Thermopile. Regarding power measurement, Bluephase II always presented the lowest values compared to the laboratory instruments. These findings suggest that the handheld radiometers utilized by practitioners (analog or digital) exhibit a wide range of irradiance values and may show lower outcomes compared to laboratory based instruments.


Assuntos
Luzes de Cura Dentária , Radiometria , Resinas Compostas , Humanos , Teste de Materiais
6.
Eur J Dent ; 13(1): 69-74, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31170753

RESUMO

OBJECTIVE: This study measured the in vivo temperature of prepared root canal walls during various stages of treatment prior to endodontic postcementation. MATERIALS AND METHODS: One tooth each from five patients requiring endodontic treatment received conventional gutta-percha obturation. The coronal 4 mm of gutta-percha was removed by drilling and the canal wall temperature was measured. A sterile, saline rinse was applied, and another temperature value was recorded. Paper points were placed, and the wall temperature was recorded. A standardized period of 1.5 minute passed, simulating time needed to mix and place the resin cement and post (no resin was placed), after which the final wall temperature was obtained. The tooth was temporized and scheduled for prosthetic reconstruction. A one-way repeated measure analysis of variance (with Tukey's post hoc test) was performed among mean temperature values for each treatment stage (preset α 0.05). RESULTS: Significant temperature differences were found among the treatment stages. Canal space drilling yielded the highest temperature (35.5 ± 0.8°C), while the lowest was obtained after saline rinsing (34.0 ± 0.9°C). The temperature of prepared root canal wall prior to postplacement (34.9 ± 1.2°C) and following paper point drying (34.8 ± 1.1°C) presented intermediate results, with no statistical difference between them. CONCLUSIONS: This study suggested that root canal wall temperature varied during various stages of preparation prior to endodontic post.

7.
J Appl Oral Sci ; 27: e20180480, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-31116279

RESUMO

OBJECTIVES: To measure and compare in vivo and in vitro pulp temperature (PT) increase (ΔTEMP) over baseline, physiologic temperature using the same intact upper premolars exposed to the same Polywave® LED curing light. METHODOLOGY: After local Ethics Committee approval (#255,945), local anesthesia, rubber dam isolation, small occlusal preparations/minute pulp exposure (n=15) were performed in teeth requiring extraction for orthodontic reasons. A sterile probe of a temperature measurement system (Temperature Data Acquisition, Physitemp) was placed within the pulp chamber and the buccal surface was sequentially exposed to a LED LCU (Bluephase 20i, Ivoclar Vivadent) using the following exposure modes: 10-s low or high, 5-s Turbo, and 60-s high. Afterwards, the teeth were extracted and K-type thermocouples were placed within the pulp chamber through the original access. The teeth were attached to an assembly simulating the in vivo environment, being similarly exposed while real-time temperature (°C) was recorded. ΔTEMP values and time for temperature to reach maximum (ΔTIME) were subjected to two-way ANOVA and Bonferroni's post-hoc tests (pre-set alpha 0.05). RESULTS: Higher ΔTEMP was observed in vitro than in vivo. No significant difference in ΔTIME was observed between test conditions. A significant, positive relationship was observed between radiant exposure and ΔTEMP for both conditions (in vivo: r2=0.917; p<0.001; in vitro: r2=0.919; p<0.001). CONCLUSION: Although the in vitro model overestimated in vivo PT increase, in vitro PT rise was close to in vivo values for clinically relevant exposure modes.


Assuntos
Luzes de Cura Dentária , Polpa Dentária/efeitos da radiação , Temperatura , Análise de Variância , Luzes de Cura Dentária/efeitos adversos , Humanos , Técnicas In Vitro , Doses de Radiação , Exposição à Radiação , Valores de Referência , Análise de Regressão , Reprodutibilidade dos Testes , Fatores de Tempo
8.
J Prosthodont Res ; 63(2): 232-238, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30598403

RESUMO

PURPOSE: The aim of this study was to evaluate the influence of indirect restorative material type and thickness on the transmission of different wavelengths from a broad-banded dental curing light. METHODS: Four dental indirect restorative materials for computer-aided design and computer-aided manufacturing (CAD/CAM) were evaluated: [RC] resin/ceramic hybrid material (Lava Ultimate), [FC] feldspathic ceramic (VitaBlocs), and two zirconia-based ceramics ([ZK] Katana; and [ZL] Lava). Total loss of irradiance (TL) was measured for blue (WB, 425-490nm) and violet (WV, 350-425nm) wavelengths. Specimens of 15×15mm with varying thicknesses (0.5, 1.0, 1.5, and 2.0mm) were fabricated (n=5). A plasma-arc dental light-curing unit was used (Arc Light-II). To assess TL as a function of wavelength, a software (Spectra Suite v5.1) connected to a spectroradiometer (USB2000) and an integrating sphere (CTSM-LSM-60-SF) was used. Data was subjected to statistical analysis (two-way ANOVA and post-hoc Tukey test, α=0.05). RESULTS: A 0.5mm interposition resulted in TL from 50.5 to 67.2%, depending on material. Increased thickness resulted in higher TL for all materials. FC showed less TL compared to ZK. In general, WV showed higher TL than did WB, and WV/WB proportion decreased with increasing thickness. CONCLUSIONS: Indirect materials significantly reduced TL, and this effect is greater with increasing thickness. WV showed lower penetration compared to WB.


Assuntos
Materiais Dentários , Cura Luminosa de Adesivos Dentários , Luz , Teste de Materiais , Cerâmica , Resinas Compostas , Desenho Assistido por Computador , Polimerização , Cimentos de Resina , Zircônio
9.
J. appl. oral sci ; 27: e20180480, 2019. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1002402

RESUMO

Abstract Objectives: To measure and compare in vivo and in vitro pulp temperature (PT) increase (ΔTEMP) over baseline, physiologic temperature using the same intact upper premolars exposed to the same Polywave® LED curing light. Methodology: After local Ethics Committee approval (#255,945), local anesthesia, rubber dam isolation, small occlusal preparations/minute pulp exposure (n=15) were performed in teeth requiring extraction for orthodontic reasons. A sterile probe of a temperature measurement system (Temperature Data Acquisition, Physitemp) was placed within the pulp chamber and the buccal surface was sequentially exposed to a LED LCU (Bluephase 20i, Ivoclar Vivadent) using the following exposure modes: 10-s low or high, 5-s Turbo, and 60-s high. Afterwards, the teeth were extracted and K-type thermocouples were placed within the pulp chamber through the original access. The teeth were attached to an assembly simulating the in vivo environment, being similarly exposed while real-time temperature (°C) was recorded. ΔTEMP values and time for temperature to reach maximum (ΔTIME) were subjected to two-way ANOVA and Bonferroni's post-hoc tests (pre-set alpha 0.05). Results: Higher ΔTEMP was observed in vitro than in vivo. No significant difference in ΔTIME was observed between test conditions. A significant, positive relationship was observed between radiant exposure and ΔTEMP for both conditions (in vivo: r2=0.917; p<0.001; in vitro: r2=0.919; p<0.001). Conclusion: Although the in vitro model overestimated in vivo PT increase, in vitro PT rise was close to in vivo values for clinically relevant exposure modes.


Assuntos
Humanos , Temperatura , Polpa Dentária/efeitos da radiação , Luzes de Cura Dentária/efeitos adversos , Doses de Radiação , Valores de Referência , Fatores de Tempo , Técnicas In Vitro , Análise de Regressão , Reprodutibilidade dos Testes , Análise de Variância , Exposição à Radiação
10.
J Adhes Dent ; 20(4): 355-363, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30206578

RESUMO

PURPOSE: To investigate the effect of polymerization stress and insertion technique on dentin micropermeability of composites placed under pulpal pressure. MATERIALS AND METHODS: One high-viscosity conventional (HC; Filtek Supreme Ultra; 3M Oral), one low-viscosity conventional (LC; Filtek Supreme Ultra Flowable; 3M Oral), one high-viscosity bulk fill (HBF; Filtek Bulk Fill Restorative; 3M Oral), and one low-viscosity bulk fill (LBF; Filtek Bulk Fill Flowable; 3M Oral) composite were evaluated. Polymerization stress was measured with materials bonded to acrylic rods in a universal testing machine (n = 5). Class I preparations were made in extracted molars, in which tooth roots were removed and the pulpal chambers cleaned. Preparations were coupled to a hydraulic device to simulate pulpal pressure during composite placement (n = 5). Conventional composites were placed in two horizontal increments, while bulk fill materials were placed in one, single increment. Fluid flow rate (µl/min) and dentin micropermeability (%) were monitored. The restoration interface was observed under confocal laser scanning microscopy. RESULTS: LC and LBF presented statistically significant higher polymerization stress than HC and HBF. Fluid flow rate and dentin micropermeability did not differ among the groups. However, different patterns of fluid infiltration and interface integrity were observed. HC and HBF presented well-sealed surrounding margins with small gaps along the pulpal wall, while HBF demonstrated more cracks in the adhesive layer. LC and LBF restorations had larger gaps along all bonded interfaces. CONCLUSION: No difference in polymerization stress was found when conventional and bulk fill composites with similar viscosities were compared. Neither polymerization stress or placement technique demonstrated a significant effect on dentin micropermeability. The incremental placement technique using a conventional, high-viscosity composite exhibited qualitatively better marginal integrity.


Assuntos
Cimentos Dentários , Materiais Dentários , Resinas Compostas , Restauração Dentária Permanente , Análise do Estresse Dentário , Dentina , Teste de Materiais , Polimerização
11.
Dent Mater ; 34(6): 901-909, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29606368

RESUMO

OBJECTIVE: This in vivo study evaluated pulp temperature (PT) rise in human premolars having deep Class V preparations during exposure to a light curing unit (LCU) using selected exposure modes (EMs). METHODS: After local Ethics Committee approval, intact first premolars (n=8) requiring extraction for orthodontic reasons, from 8 volunteers, received infiltrative and intraligamental anesthesia and were isolated using rubber dam. A minute pulp exposure was attained and sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted into the coronal pulp chamber to continuously monitor PT (°C). A deep buccal Class V preparation was prepared using a high speed diamond bur under air-water spray cooling. The surface was exposed to a Polywave® LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs, allowing 7-min span between each exposure: 10-s in low (10-s/L), 10-s (10-s/H), 30-s (30-s/H), or 60-s (60-s/H) in high mode; and 5-s-Turbo (5-s/T). Peak PT values and PT increases over physiologic baseline levels (ΔT) were subjected to 1-way, repeated measures ANOVAs, and Bonferroni's post-hoc tests (α=0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. RESULTS: All EMs produced higher peak PT than the baseline temperature (p<0.001). Only 60-s/H mode generated an average ΔT of 5.5°C (p<0.001). A significant, positive relationship was noted between applied radiant exposure and ΔT (r2=0.8962; p<0.001). SIGNIFICANCE: In vivo exposure of deep Class V preparation to Polywave® LED LCU increases PT to values considered safe for the pulp, for most EMs. Only the longest evaluated EM caused higher PT increase than the critical ΔT, thought to be associated with pulpal necrosis.


Assuntos
Luzes de Cura Dentária , Preparo da Cavidade Dentária/métodos , Polpa Dentária/efeitos da radiação , Dente Pré-Molar , Temperatura Alta , Humanos , Extração Dentária
12.
Braz. dent. j ; 29(1): 76-81, Jan.-Feb. 2018. tab, graf
Artigo em Inglês | LILACS | ID: biblio-888717

RESUMO

Abstract The aim of this study was to evaluate Knoop hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microhardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 ºC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p<0.0001), mode of activation (p<0.001), post-cure time (p<0.0001) and depth (p<0.0001) were detected. No significant interactions (p>0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop hardness. Indirect activation through a ceramic material reduced significantly Knoop hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop hardness.


Resumo O objetivo deste estudo foi avaliar a dureza Knoop de diferentes cores de um cimento resinoso fotoativado diretamente ou através da interposição de um disco de cerâmica, medindo 15 min ou 24 h após exposição à luz, em diferentes profundidades. Amostras do cimento resinoso (Variolink Veneer) em sete cores foram fabricados num molde de elastômero, coberto com tira de poliéster, seguido de um disco cerâmico (IPS e.max Press) com 0.7 mm de espessura e fotoativado por 20 s com o aparelho LED (IPS e.max Press). O cimento resinoso fotoativado foi transversalmente desgastado na porção média e os valores de microdureza Knoop foram obtidos após 15 min após exposição à luz e após armazenagem em água deionizada à 37 °C por 24 h. Cinco penetrações foram feitas na secção transversal à 100 e 700 μm da superfície de topo. Dez amostras foram confeccionadas para cada condição de teste. Os dados foram submetidos à Análise de Variância em esquema de parcelas subdivididas (cor, tempo pós-ativação, modo de ativação e profundidade), seguido pelo teste de Tukey post hoc (α=0,05). Diferença significante para a cor (p<0,0001), modo de ativação (p<0,001), tempo pós-ativação (p<0,0001) e profundidade (p<0,0001) foi detectada. Nenhuma interação significante foi encontrada (p>0,05), exceto para a interação cor x tempo pós-ativação (p<0,0045) e modo de ativação x tempo pós-ativação (p<0,0003). A cor do cimento resinoso teve significante efeito na dureza Knoop. A ativação indireta através do material cerâmico reduziu significativamente a dureza Knoop. A dureza Knoop aumentou significativamente após 24 h em todas as cores do cimento comparados aos valores obtidos após 15 min. A profundidade do cimento resinoso reduziu significativamente os valores de dureza Knoop.


Assuntos
Cerâmica , Cor , Dureza , Cimentos de Resina , Luzes de Cura Dentária , Polimerização
13.
Braz Dent J ; 29(1): 76-81, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29267529

RESUMO

The aim of this study was to evaluate Knoop hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microhardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 ºC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 µm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p<0.0001), mode of activation (p<0.001), post-cure time (p<0.0001) and depth (p<0.0001) were detected. No significant interactions (p>0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop hardness. Indirect activation through a ceramic material reduced significantly Knoop hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop hardness.


Assuntos
Cerâmica , Cor , Dureza , Cimentos de Resina , Luzes de Cura Dentária , Polimerização
14.
Braz Oral Res ; 31(suppl 1): e61, 2017 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-28902241

RESUMO

Contemporary dentistry literally cannot be performed without use of resin-based restorative materials. With the success of bonding resin materials to tooth structures, an even wider scope of clinical applications has arisen for these lines of products. Understanding of the basic events occurring in any dental polymerization mechanism, regardless of the mode of activating the process, will allow clinicians to both better appreciate the tremendous improvements that have been made over the years, and will also provide valuable information on differences among strategies manufacturers use to optimize product performance, as well as factors under the control of the clinician, whereby they can influence the long-term outcome of their restorative procedures.


Assuntos
Luzes de Cura Dentária , Cimentos Dentários/química , Cura Luminosa de Adesivos Dentários/instrumentação , Cura Luminosa de Adesivos Dentários/métodos , Fotoiniciadores Dentários/química , Polimerização , Absorção de Radiação , Cimentos Dentários/efeitos da radiação , Restauração Dentária Permanente/instrumentação , Restauração Dentária Permanente/métodos , Polimerização/efeitos da radiação , Doses de Radiação , Temperatura , Fatores de Tempo
15.
Dent Mater ; 33(11): 1266-1273, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28826611

RESUMO

OBJECTIVE: This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). METHODS: After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni's post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. RESULTS: Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. SIGNIFICANCE: Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD.


Assuntos
Luzes de Cura Dentária , Gengiva/efeitos da radiação , Temperatura , Animais , Lesões por Radiação/prevenção & controle , Suínos
16.
Braz. oral res. (Online) ; 31(supl.1): e61, Aug. 2017. graf
Artigo em Inglês | LILACS | ID: biblio-889452

RESUMO

Abstract Contemporary dentistry literally cannot be performed without use of resin-based restorative materials. With the success of bonding resin materials to tooth structures, an even wider scope of clinical applications has arisen for these lines of products. Understanding of the basic events occurring in any dental polymerization mechanism, regardless of the mode of activating the process, will allow clinicians to both better appreciate the tremendous improvements that have been made over the years, and will also provide valuable information on differences among strategies manufacturers use to optimize product performance, as well as factors under the control of the clinician, whereby they can influence the long-term outcome of their restorative procedures.


Assuntos
Luzes de Cura Dentária , Cimentos Dentários/química , Cura Luminosa de Adesivos Dentários/instrumentação , Cura Luminosa de Adesivos Dentários/métodos , Fotoiniciadores Dentários/química , Polimerização , Absorção de Radiação , Cimentos Dentários/efeitos da radiação , Restauração Dentária Permanente/instrumentação , Restauração Dentária Permanente/métodos , Polimerização/efeitos da radiação , Doses de Radiação , Temperatura , Fatores de Tempo
17.
J Esthet Restor Dent ; 28(1): 29-42, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26177387

RESUMO

PURPOSE: Previous research investigated the effects of curing tip barriers on light output and composite properties, but no study has measured the effect of a wide variety of barriers and curing light types on delivered radiant exposure and the resulting composite cure 2 mm below the radiated surface. MATERIALS AND METHODS: Six barrier materials and six curing light types were tested. Spectroradiometry was used to measure irradiance with and without barriers for each light type, and radiant exposure values were determined for a commercial camphorquinone-based dental composite material. Composite monomer conversion was measured at 10 minutes following exposure for each light type/barrier condition (N = 5) using infrared spectroscopy. Results were subjected to one-way analyses of variance for radiant exposure and conversion among barrier types within a given curing light: preset alpha 0.05. RESULTS: All barriers significantly reduced radiant exposure compared with the uncovered tip, but the use of the two polywave LEDs covered with a latex-based barrier demonstrated significantly lower conversion values. CONCLUSIONS: Although light-curing barriers reduce radiant exposure to a restorative material over a recommended exposure, this reduction is not sufficient to cause significant reduction in composite cure, except when using a latex-based barrier and a polywave LED curing light. CLINICAL SIGNIFICANCE: Clinicians need to be aware of the possible interaction between curing light barriers and curing light type in order to optimally photocure restorative materials.


Assuntos
Luzes de Cura Dentária , Resinas Compostas , Materiais Dentários
18.
Dent Mater ; 31(12): 1542-51, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26608118

RESUMO

OBJECTIVE: To evaluate degree of conversion (DC), Knoop microhardness (KHN), internal marginal adaptation (IA), and polymerization shrinkage stress (PS) of one conventional and four bulk-fill composites. METHODS: Bulk-fill composites tested were Surefil SDR (SDR), Filtek Bulk-Fill (FBF), Tetric EvoCeram Bulk-Fill (TEC), and EverX Posterior (EXP). The conventional composite Herculite Classic (HER) was tested using both incremental and bulk-fill insertion techniques. Standardized Class I preparations (4-mm-depth) were made in extracted molars and restored with each product system (N=5). After 1-week wet storage, restorations were cross-sectioned and DC and KHN were evaluated at four depths (1, 2, 3, and 4mm) using confocal Raman spectroscopy and KHN techniques, respectively. Epoxy resin replicas of restorations were evaluated using scanning electron microscopy for IA. PS was determined using composite bonded to acrylic rods attached to a universal testing machine (N=5). RESULTS: Within bulk-fill products, only SDR and FBF demonstrated similar DC at all depths, and KHN values did not statistically differ among depths, except for TEC. Neither placement method nor depth affected KHN or DC, except the DC of HER bulk-fill at 4mm. Incrementally layered HER, and bulk-fills SDR and TEC demonstrated the lowest proportion of internal gaps. Highest and lowest PS values were measured for EXP and TEC, respectively. SIGNIFICANCE: DC with depth was not uniform among all bulk-fill materials, although no difference in KHN was found. Higher PS correlated positively with higher proportion of interfacial gaps. The incremental technique using conventional composite showed reduced gap formation.


Assuntos
Resinas Compostas/química , Adaptação Marginal Dentária , Materiais Dentários/química , Restauração Dentária Permanente/métodos , Dureza , Humanos , Técnicas In Vitro , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Dente Serotino , Polimerização , Propriedades de Superfície
19.
Braz Dent J ; 26(4): 363-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26312973

RESUMO

This study evaluated the effects of indirect restorative materials, curing conditions and time on the degree of conversion (DC) of a dual-cured resin cement using infrared spectroscopy. The resin cement (RelyX Unicem 2, 3M ESPE) was applied to the diamond surface of a horizontal attenuated-total-reflectance unit and activated using one of following conditions: self-cure, direct light exposure, light exposure through indirect restorative materials (resin nano-ceramic: Lava Ultimate, 3M ESPE or feldspathic ceramic: Vita Blocks Mark II, Vita Zahnfabrik). Four thicknesses (0.5, 1.0, 1.5 or 2.0 mm) of each indirect material were analyzed, and the light-activation was performed using a blue LED light. Data (n=5) were analyzed by three-way ANOVA, Tukey's post hoc and Dunnett's tests (α=5%). No significant differences in DC were observed between indirect materials of similar thickness. All groups exhibited higher DC after 10 min than after 5 min. At both times points, the self-cure group exhibited significantly lower DC than all the light exposure groups. Only when the overlying indirect restoration had a thickness of 2 mm did DC decrease significantly. The presence of a thick, indirect restoration can decrease the DC of resin cement. DC after 10 min was higher than after 5 min. The self-cure mode yielded lower DC than the light-activating one.


Assuntos
Luz , Cimentos de Resina/química , Espectroscopia de Infravermelho com Transformada de Fourier
20.
Braz. dent. j ; 26(4): 363-367, July-Aug. 2015. tab, ilus
Artigo em Inglês | LILACS | ID: lil-756382

RESUMO

This study evaluated the effects of indirect restorative materials, curing conditions and time on the degree of conversion (DC) of a dual-cured resin cement using infrared spectroscopy. The resin cement (RelyX Unicem 2, 3M ESPE) was applied to the diamond surface of a horizontal attenuated-total-reflectance unit and activated using one of following conditions: self-cure, direct light exposure, light exposure through indirect restorative materials (resin nano-ceramic: Lava Ultimate, 3M ESPE or feldspathic ceramic: Vita Blocks Mark II, Vita Zahnfabrik). Four thicknesses (0.5, 1.0, 1.5 or 2.0 mm) of each indirect material were analyzed, and the light-activation was performed using a blue LED light. Data (n=5) were analyzed by three-way ANOVA, Tukey's post hoc and Dunnett's tests (α=5%). No significant differences in DC were observed between indirect materials of similar thickness. All groups exhibited higher DC after 10 min than after 5 min. At both times points, the self-cure group exhibited significantly lower DC than all the light exposure groups. Only when the overlying indirect restoration had a thickness of 2 mm did DC decrease significantly. The presence of a thick, indirect restoration can decrease the DC of resin cement. DC after 10 min was higher than after 5 min. The self-cure mode yielded lower DC than the light-activating one.

.

Este estudo avaliou os efeitos do tipo de material restaurador indireto, da condição de ativação e do tempo no grau de conversão de um cimento resinoso de dupla ativação, utilizando espectroscopia de luz infravermelha. O cemento resinoso (RelyX Unicem 2, 3M ESPE) foi aplicado à superfície do diamante da unidade de reflectância atenuada e ativado segundo as seguintes condições: ativação química, exposição direta da luz e aplicação da luz através de dois materiais protéticos: resina nano-cerâmica (Lava Ultimate, 3M ESPE) ou cerâmica feldspática (Vita Blocks Mark II, Vita Zahnfabrik). Quatro espessuras de cada um desses materiais (0,5; 1,0; 1,5 e 2,0 mm) foram analisadas e a ativação realizada com luz LED. Os dados (n=5) foram analisados pela ANOVA três fatores, testes de Tukey e Dunnett (5%). Nenhuma diferença do grau de conversão foi observada entre os materiais. Todos os grupos mostraram maior grau de conversão após 10 min que após 5 min. Em ambos os tempos, o grupo ativado quimicamente teve menor grau de conversão que todos os grupos fotoativados. O grau de conversão foi reduzido somente quando foi utilizada a peça protética de 2 mm. Espessas peças protéticas podem reduzir o grau de conversão do cemento resinoso. A grau de conversão após 10 min é maior que após 5 min da cimentação. A ativação química produz menor grau de conversão que a fotoativação.

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Assuntos
Luz , Cimentos de Resina/química , Espectroscopia de Infravermelho com Transformada de Fourier
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