Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.050
Filtrar
1.
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
2.
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
3.
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
4.
Compend Contin Educ Dent ; 42(2): 93-94, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33735582

RESUMO

Composite materials remain a mainstay as a restorative option in dentistry. This article reviews some of the most recent updates and projected future trends in dental composites, along with curing lights and matrix systems.


Assuntos
Luzes de Cura Dentária , Bandas de Matriz , Resinas Compostas , Materiais Dentários , Teste de Materiais
5.
Dental Press J Orthod ; 26(1): e2119150, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33729290

RESUMO

INTRODUCTION: Third generation of LED light curing units might be used in short exposure periods for orthodontic brackets bonding. OBJECTIVE: This study evaluated the effect of the different radiant exposure (RE) values: Manufacturers' instructions (MI), ½ MI, 1/4 MI and Turbo mode. Two third-generation LED curing units were used: VALO® and Bluephase 20i® . The degree of conversion (DC) and Vickers hardness (VHN) of an orthodontic composite (OC) (Transbond XT) under metallic (MB) or ceramic brackets (CB) were measured. METHODS: OC was applied to the bracket base, which was then placed over an attenuated total reflectance (ATR) table coupled to an infrared light spectroscope, or to a glass surface for the VHN analysis. The specimens were light-cured and DC values were calculated. The VHN was obtained in a microhardness tester. The data were analyzed with 2-way ANOVA followed by Tukey's post-hoc test (pre-set α=0.05). Linear regression analysis evaluated the relationship between RE values and dependent variables. RESULTS: CB allowed higher DC and VHN values than MB (p< 0.001). No significant difference was noted among groups when CB were used. For MB, MI groups showed the highest DC and VHN values. A significant, but weak relationship was found between delivered RE values and dependent variables. CONCLUSIONS: The decrease in RE values from third generation LED CU did not jeopardize the DC values when CB were used, but can compromise DC and VHN values when MB are used.


Assuntos
Luzes de Cura Dentária , Braquetes Ortodônticos , Cerâmica , Resinas Compostas , Dureza , Teste de Materiais , Polimerização , Cimentos de Resina , Propriedades de Superfície
6.
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
7.
J Am Dent Assoc ; 152(4): 260-268, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33637301

RESUMO

BACKGROUND: Light-emitting diode (LED) and quartz-tungsten-halogen (QTH) curing lights are used commonly in clinics. The aim of this study was to assess the effect of these lights on the proliferation of human gingival epithelial cells. METHODS: Smulow-Glickman (S-G) cells were exposed to a VALO LED (Ultradent) or an XL3000 QTH (3M ESPE) light at 1 millimeter or 6 mm distance for 18, 39, 60, and 120 seconds. Untreated and Triton X-100 treated cells were used as controls. At 24, 48, and 72 hours after light exposure, cell proliferation was evaluated via a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS: The authors first evaluated the performances of these 2 lights. Both LED and QTH lights generated heat. The LED light generated less heat than the QTH light and could save approximately two-thirds of the curing time. When used for 18 seconds at a 6 mm distance, the LED light did not inhibit the proliferation of S-G cells. However, if the exposure time was longer (for example, 39, 60, or 120 seconds), the LED light inhibited cell proliferation. The inhibitory effect increased when the exposure time was increased to 39, 60, or 120 seconds. The QTH light did not inhibit S-G cell proliferation if the exposure time was less than 120 seconds. CONCLUSIONS: Prolonged exposure to a blue curing light (both LED and QTH) inhibits the proliferation of gingival epithelial cells and may cause damages to oral soft tissues. PRACTICAL IMPLICATIONS: In dental practices, a balance should be struck in consideration of curing time not only to cure the composites completely but also to minimize unnecessarily prolonged light exposure.


Assuntos
Resinas Compostas , Quartzo , Proliferação de Células , Luzes de Cura Dentária , Dureza , Humanos , Teste de Materiais
8.
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
9.
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
11.
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
12.
J Contemp Dent Pract ; 21(6): 615-620, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025928

RESUMO

AIM: The aim of this study is to compare the effect of the use of second-generation and third-generation LED light-curing units (LCUs) on the degree of conversion (DC) and microhardness (VHN) of bulk-fill resin composites. MATERIALS AND METHODS: Thirty cylindrical specimens (each n = 5) of Tetric N-Ceram Bulk-Fill, Filtek™ Bulk-Fill Posterior Restorative, and SDR flow were prepared in metal molds (5 mm in diameter and 4 mm in thickness) and cured with second-generation LED (SmartLite® Focus®, Dentsply Sirona) and third-generation LED (Bluephase® style, Ivoclar Vivadent) resulting in six groups. Degree of conversion was determined using Fourier transform infrared spectroscopy (FTIR), and microhardness with Vickers microhardness tester. Data were statistically analyzed using one-way ANOVA and least significance difference (LSD) test, and DC and microhardness were correlated using Pearson's correlation (α = 0.05). RESULTS: There was a significant difference between DC and VHN between all groups of bulk-fill which were cured by second-generation LED curing light and third-generation LED curing light. Then there is no significant difference between DC of the three composite bulk-fill resins by (second-generation LED vs third-generation LED curing light). CONCLUSION: The second-generation LED curing light can still be used to cure bulk-fill resin composites by increasing the duration of irradiation. CLINICAL SIGNIFICANCE: In the microhardness test, there was a significant difference in the Filtek™ Bulk-Fill Posterior Restorative resin composites.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , Teste de Materiais , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier
13.
J Orofac Orthop ; 81(6): 396-406, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32875349

RESUMO

PURPOSE: During bracket bonding, patients often report about thermosensitivity. The reason could be that modern light emitting diode (LED) light curing units run with intensities up to 3200 mW/cm2. In this in vitro pilot study with nonpulpal circulation approaches, the temperatures in the pulpal cavity were measured. METHODS: The study included 60 extracted teeth divided into four equal groups: lower and upper incisors, premolars and molars. Starting at 37 °C (body temperature) as the reference, the temperature increase was measured for the first series on each tooth without a bracket, without and with a recommended hygienic barrier case for the LED light curing unit, and exposition to light once versus twice. The distance between the tooth and light curing unit was 3 mm. In the second test series, a metal bracket was also bonded to each tooth. In the third series, the light exposition distance was increased to 4 mm. RESULTS: In all three test series, significant intrapulpal temperature increase was found: The highest temperatures were recorded after exposure to light once without the hygienic barrier case. In the first test series, this approach showed temperatures even higher than 42.5 °C in the lower incisors (average 42.99 ± 2.23 °C) and premolars (average 42.94 ± 2.15 °C). CONCLUSIONS: Significant increases in the temperature of the pulpal cavity (up to 42.5 °C) may occur during bonding brackets according to the manufacturer's recommendation with an LED light curing unit with in vitro nonpulpal circulation approaches. Therefore it could be reasonable to critically question the recommendation of the manufacturer.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Luzes de Cura Dentária , Cavidade Pulpar , Humanos , Projetos Piloto , Temperatura
14.
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
15.
Int Dent J ; 70(6): 407-417, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32696512

RESUMO

INTRODUCTION: This article describes the features that should be considered when describing, purchasing and using a light-curing unit (LCU). METHODS: The International System of Units (S.I.) terms of radiant power or radiant flux (mW), spectral radiant power (mW/nm), radiant exitance or tip irradiance (mW/cm2 ), and the irradiance received at the surface (also in mW/cm2 ) are used to describe the output from LCU. The concept of using an irradiance beam profile to map the radiant exposure (J/cm2 ) from the LCU is introduced. RESULTS: Even small changes in the active tip diameter of the LCU will have a large effect on the radiant exitance. The emission spectra and the effects of distance on the irradiance delivered are not the same from all LCUs. The beam profile images show that using a single averaged irradiance value to describe the LCU can be very misleading. Some LCUs have 'hot spots' of high radiant exitance that far exceed the current ISO 10650 standard. Such inhomogeneity may cure the resin unevenly and may also be dangerous to soft tissues. Recommendations are made that will help the dentist when purchasing and then safely using the LCU. CONCLUSIONS: Dental manufacturers should report the radiant power from their LCU, the spectral radiant power, information about the compatibility of the emission spectrum from the LCU with the photoinitiators used, the active optical tip diameter, the radiant exitance, the effect of distance from the tip on the irradiance delivered, and the irradiance beam profile from the LCU.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , Equipamentos Odontológicos , Humanos , Teste de Materiais
16.
Shanghai Kou Qiang Yi Xue ; 29(1): 13-18, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-32524114

RESUMO

PURPOSE: To study the optical properties of two common dental light curing units and the optical properties of the transmitted light after transmitting glass ceramics. METHODS: Two types of glass-ceramic disc named IPS e.max CAD and IPS Empress CAD were produced by CAD/CAM technology, and the colors of A2 and A3 were chosen for each type of glass ceramic, then divided into 4 groups. Eight discs were made 0.5 mm to 4.0 mm thick in each group, the total number was 32. Spectra irradiance meter and power meter were used to measure the central wavelengths and irradiance of 3 power modes of 2 new LED light curing units before and after transmitting glass-ceramic discs. Statistical analysis was performed using SPSS 25.0 software package. RESULTS: Under different power modes of light curing units, different types and colors of glass ceramics, the central wavelengths of transmitted light were significantly different (P<0.05). Under different power modes of light curing units, different types, colors and thicknesses of glass ceramics, the irradiance of transmitted light was significantly different (P<0.05). CONCLUSIONS: The power mode of light curing unit, the type and color of the glass ceramic have influence on the central wavelength of the transmitted light, but the thickness of the glass ceramic has no influence on the central wavelength of the transmitted light. The power mode of the light curing unit, the type, color, and thickness of the glass ceramic have influence on the irradiance of the transmitted light, in which glass ceramic thickness has the most significant effect on the attenuation of the irradiance of the transmitted light.


Assuntos
Cerâmica , Luzes de Cura Dentária , Cor , Desenho Assistido por Computador , Porcelana Dentária , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície
17.
J Am Dent Assoc ; 151(7): 544-545.e2, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32498964

RESUMO

BACKGROUND: The ability to polymerize light-activated dental materials with dental light-curing units (DLCUs) has revolutionized dentistry. However, proper DLCU use is essential for ensuring the effectiveness and performance of these materials. METHODS: The authors developed an electronic cross-sectional survey in the American Dental Association Qualtrics Research Core platform. The survey included questions about DLCU use, unit type and selection, training, maintenance, technique, and safety measures. The authors deployed the survey to 809 American Dental Association Clinical Evaluators (ACE) panelists on October 9, 2019, and sent reminder links to nonrespondents 1 week later. They conducted exploratory and descriptive analyses using SAS software Version 9.4. RESULTS: Of the 353 ACE panelists who completed the survey, most used a DLCU in their practices (99%), and light-emitting diode multiwave units were the most common type of DLCU units (55%). Dentists use DLCUs for over one-half of their appointments each day (mean [standard deviation], 59% [22%]). Regarding technique, respondents reported that they modify their curing technique on the basis of material thickness (79%) and material type or light tip-to-target distances (59%). Maintenance practices varied, with two-thirds of respondents reporting that they periodically check their DLCUs' light output. CONCLUSIONS: DLCUs are an integral part of a general dentist's daily practice, but maintenance, ocular safety, and technique varied widely among this sample. PRACTICAL IMPLICATIONS: Because clinical effectiveness requires delivery of an adequate amount of light energy at the appropriate wavelength, variation in DLCU maintenance, safety, and techniques suggest that dentists could benefit from additional guidance and training on DLCU operation.


Assuntos
Resinas Compostas , Luzes de Cura Dentária , American Dental Association , Estudos Transversais , Inquéritos e Questionários , Estados Unidos
18.
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
19.
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
20.
J Endod ; 46(3): 425-430, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32037054

RESUMO

INTRODUCTION: The purpose of this study was to investigate the influence of both polymerization cycles and mechanical exposure procedures on the adhesion of instrument fragments using a modified tube technique with a light-curing composite. METHODS: Eighty Mtwo instruments (size 15.05; VDW, Munich, Germany) were cut at a diameter of 35/100 mm and clamped in a vice with an overlap of 2 mm. Matching cannulas were filled with SDR composite (Dentsply, York, PA) and placed over the instruments. Prime & Bond Active (Dentsply Sirona, Bensheim, Germany) was used as the bonding material. Glass fiber was inserted from the opposite side into the cannula, and 1, 2, 4, or 6 polymerization cycles of 30 seconds were applied (800 mW/mm2) (n = 20/group). Sixty further identical instruments (n = 20/group) were divided into the following groups: group 1, cut at 10 mm and left unprepared (taper = 5%); group 2, parallelized using diamond instruments (taper = 0%); and group 3, prepared in a way that an inverted conical taper resulted (taper = 2%). Polymerization was performed for 2 minutes. The failure load and mode of failure were determined using a tensile testing device (2 mm/min). Data were statistically analyzed using the Kruskal-Wallis or chi-square test. RESULTS: The failure load increased significantly with the number of polymerization cycles (P < .0001). More than 4 polymerization cycles had no further benefit (P > .05). The failure load in the inverted conical group was significantly lower (P < .0001) compared with the parallel and the unprepared groups. Adhesive failure was significantly more frequent in groups 2 and 3 (20/20) than in group 1 (16/20) (P < .05). CONCLUSIONS: Both the number of polymerization cycles and the mechanical exposure procedures had a significant impact on the adhesive force when using the tube technique.


Assuntos
Luzes de Cura Dentária , Cavidade Pulpar , Preparo de Canal Radicular , Alemanha , Teste de Materiais , Polimerização , Estresse Mecânico , Titânio
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...