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1.
Saudi Dent J ; 29(2): 48-58, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28490843

RESUMO

AIM: The aim of this review was to help clinicians improve their understanding of the polymerization process for resin-based composites (RBC), the effects of different factors on the process and the way in which, when controlled, the process leads to adequately cured RBC restorations. METHODS: Ten factors and their possible effects on RBC polymerization are reviewed and discussed, with some recommendations to improve that process. These factors include RBC shades, their light curing duration, increment thickness, light unit system used, cavity diameter, cavity location, light curing tip distance from the curing RBC surface, substrate through which the light is cured, filler type, and resin/oral cavity temperature. CONCLUSION: The results of the review will guide clinicians toward the best means of providing their patients with successfully cured RBC restorations.

2.
Eur J Dent ; 11(1): 22-28, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28435361

RESUMO

OBJECTIVE: To evaluate the effects of curing two resin-based composites (RBC) with the same radiant exposures at 730, 1450, and 2920 mW/cm2. MATERIALS AND METHODS: Two types of RBC, Filtek Supreme Ultra and Tetric-EvoCeram-Bulk Fill, were light-cured to deliver the same radiant exposures for 5, 10, or 20 s by means of a modified Valo light emitted diode light-curing unit with the light tip placed directly over each specimen. The RBC was expressed into metal rings that were 2.0 and 4.0 mm in thickness, directly on an attenuated total reflectance Fourier transform infrared plate heated to 33°C, and the degree of conversion (DC) of the RBC was recorded. The specimens were then removed and the Knoop microhardness (KHN) was tested at both the bottom and the top of each specimen. The KHN was tested again after 24 h and 7 days of storage in the dark at 37°C and 100% humidity. The DC and KHN results were analyzed with Fisher's protected least significant difference at α = 0.05. RESULTS: The DC values for the specimens cured at the three different irradiance levels were similar. However, at different depths, there were differences in the DC values. In general, there were no clear differences among the samples cured in the three different groups, and the KHN was always greater 24 h and 7 days later (P < 0.05). CONCLUSIONS: Despite the curing time, and as long as the samples were cured with the same radiant exposures, there were no significant effects on the DC and KHN of both RBCs.

3.
J Contemp Dent Pract ; 17(3): 217-23, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27207201

RESUMO

OBJECTIVE: Dental materials are often made at room temperature, whereas clinically they are made in the mouth. This study evaluated the effects of temperature on the degree of conversion (DC) and Knoop microhardness (KHN). MATERIALS AND METHODS: Two types of resin-based composites (RBCs) were light-cured using a light-emitting diode (LED) light-curing unit. The resin specimens were centered on an Attenuated Total Reflectance Fourier transform infrared (FT-IR) plate heated to 23°C or 33°C. The DC of the resin was calculated after 120 seconds, the specimens were removed, and the KHN was tested at the bottom of the specimens both immediately, after 24 hours, and after 7 days storage in distilled water in complete darkness at 37°C. The effects of different temperatures on the DC and KHN with their storage time were compared by analysis of variance and Fisher's protected least significant difference post hoc multiple comparison tests (p < 0.05). RESULTS: Increasing the temperature had a significant and positive effect on the DC and KHN for immediate values of the RBCs. Greater conversion and hardness occurred when the curing temperature was increased from 23°C to 33°C. The KHN increased significantly after 24 hours of storage. There was a linear relationship between DC and KHN (R(2) = 0.86) within the range of DC and KHN studied. CONCLUSION: The physical properties of dental materials can be expected to be better when made in the mouth than when they are made in a laboratory at room temperature.


Assuntos
Resinas Acrílicas , Resinas Compostas , Poliuretanos , Temperatura , Dureza , Fatores de Tempo
4.
Eur J Prosthodont Restor Dent ; 24(3): 138-144, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28509505

RESUMO

This study evaluated the effect of light-curing through two ceramics on the degree of conversion-(DC) and Knoop microhardness-(KHN) of resin cements. Three shades were used and light-cured directly on a Golden Gate attenuated total reflectance FT-IR plate at 30°C. KHN was tested immediately and after 24-h. Resin shade, type of ceramic, and storage time all had significant effects on the DC and KHN values. Within each shade, the choice of ceramic always had a significant effect, but the shade of the resin had a greater effect. There was an increase in KHN of all cements after 24-h of storage.


Assuntos
Luzes de Cura Dentária , Porcelana Dentária , Cimentos de Resina , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier
5.
J Dent ; 45: 14-8, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26593741

RESUMO

OBJECTIVE: To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco). METHODS: The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition. RESULTS: As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA p<0.05). Although the KHN of SureFil SDR Flow was only marginally significantly different between the 2 and 6-mm thickness, the bottom at 6-mm was only 59% of the hardness measured at the top. CLINICAL SIGNIFICANCE: This study highlights that clinicians need to consider how the depth of cure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin.


Assuntos
Bis-Fenol A-Glicidil Metacrilato/efeitos da radiação , Luzes de Cura Dentária , Materiais Dentários/efeitos da radiação , Resinas Acrílicas/química , Resinas Acrílicas/efeitos da radiação , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Materiais Dentários/química , Análise do Estresse Dentário , Cura Luminosa de Adesivos Dentários/instrumentação , Cura Luminosa de Adesivos Dentários/métodos , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Polimerização/efeitos da radiação , Poliuretanos/química , Poliuretanos/efeitos da radiação , Propriedades de Superfície/efeitos da radiação
6.
J Adhes Dent ; 16(2): 129-35, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24179989

RESUMO

PURPOSE: This study measured the effects of using three different exposure times to cure one resin cement through two types of ceramic. MATERIALS AND METHODS: One light-curing resin cement (Variolink II, Ivoclar Vivadent) was exposed for 20 s, 40 s, or 60 s with a BluePhase G2 light (Ivoclar Vivadent) on the high power setting through 1.0 mm of either ZirPress (ZR) or Empress Esthetic (EST) ceramic (Ivoclar Vivadent). The degree of conversion (DC) of the resin was measured 100 s after light exposure. The Knoop microhardness (KHN) was measured 5 min after light exposure and again after 24 h. The DC and KHN results were analyzed with ANOVA followed by Scheffe's post-hoc multiple comparison tests at α = 0.05. RESULTS: Increasing exposure time had a significant effect on the KHN and DC values for the resins exposed through both ceramics. As exposure times increased, the influence of the ceramic was reduced; however, the microhardness values were greater for the cement exposed through EST ceramic. When the exposure time was increased from 20 s to 40 s, microhardness values for the resin increased by 39.6% through the EST ceramic. When exposed for 60 s, there were no differences between the 100-s DC values or 5-min KHN values using either ceramic (p > 0.05). There was an excellent correlation between the DC at 100 s and the microhardness values measured at 5 min. CONCLUSION: Resin polymerization was greater through EST than ZR ceramic. At least 40 s to 60 s from the Blue- Phase G2 on high power mode is required to cure this resin cement through 1.0 mm of ceramic.


Assuntos
Cerâmica/química , Porcelana Dentária/química , Cimentos de Resina/química , Silicatos de Alumínio/química , Apatitas/química , Luzes de Cura Dentária/classificação , Dureza , Humanos , Cura Luminosa de Adesivos Dentários/métodos , Teste de Materiais , Polimerização , Doses de Radiação , Fatores de Tempo
7.
J Adhes Dent ; 15(6): 547-51, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23653902

RESUMO

PURPOSE: This study examined the effect of selecting a single-peak blue vs a polywave blue/violet emission LED curing light on the degree of conversion (DC) and Knoop microhardness (KHN) of resin cements when light cured through a ceramic disk. MATERIALS AND METHODS: Two shades (A1 and A4) of resin cement (Variolink II) were placed in a 0.5-mm-thick ring. The top surfaces were covered with a Mylar strip and further covered with a disk of 1-mm-thick Empress Esthetic ceramic, shade A2. The specimens were light cured by means of an Elipar-S10 (3M ESPE, single-peak blue LED) or BluePhase-G2 (Ivoclar Vivadent, polywave blue/violet LED) curing light, both for 20 s, directly on the surface of an attenuated total reflectance FT-IR plate at 30°C. The DC of the resin was calculated after 100 s. The specimens were removed, and the Knoop microhardness was tested immediately and again after 24-h storage in the dark at 37°C and 100% humidity. Five specimens were made in each group. The DC and Knoop microhardness results were analyzed with ANOVA and Fisher's PLSD at α = 0.05. RESULTS: The choice of curing light had no significant effect on the DC and only a small effect on the immediate and 24-h KHN values. Shade A4 of the resin cement was harder and had a higher DC than shade A1. CONCLUSION: When light cured for 20 s, Variolink II resin cement can be light cured with either the single-peak or the polywave curing light. Shade A4 of the cement was slightly harder than A1.


Assuntos
Luzes de Cura Dentária/classificação , Cimentos de Resina/química , Silicatos de Alumínio/química , Cor , Escuridão , Porcelana Dentária/química , Dureza , Humanos , Umidade , Cura Luminosa de Adesivos Dentários/instrumentação , Cura Luminosa de Adesivos Dentários/métodos , Teste de Materiais , Fibras Ópticas , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura , Fatores de Tempo
8.
Dent Mater J ; 31(3): 354-61, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22673474

RESUMO

The purpose of this study was to quantitatively evaluate the effects of different shades of light-polymerized resin cement on the color of two different thicknesses (0.5 mm and 0.7 mm) of three different ceramic materials (Esthetic, e.max, and ZirPress). A spectrophotometer (Color Eye 7000A - CIE (L*a*b*) was used to measure the color of specimens on the control substrate without cement, and then on (Translucent, White Opaque, B0.5, A1, and A3 of RelyX™ Veneer cement). The mean values of color difference (ΔE) were higher for Esthetic, followed by ZirPress, with the lowest values for e.max. The mean values of ΔE decreased when the thickness of ceramic increased from 0.5 mm to 0.7 mm. It was observed that the White Opaque had significantly increased ΔE values when compared with (TR, B0.5, A1, and A3), whereas no significant difference between B0.5 and TR, and between B0.5 and A3.


Assuntos
Cor , Porcelana Dentária , Facetas Dentárias , Cimentos de Resina , Silicatos de Alumínio , Apatitas , Porcelana Dentária/química , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Espectrofotometria
9.
Saudi Dent J ; 24(3-4): 163-7, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23960546

RESUMO

OBJECTIVES: To evaluate the distribution of light-curing units (LCU) used in an urban area (Riyadh) and a rural area (Kharj) of Saudi Arabia, and to compare their irradiance values. METHODS: The study involved three dental centers in urban areas and two in rural areas, all of which were parts of a single healthcare institution providing dental services. The light outputs (power mW) from 140 LCUs were measured by laboratory-grade spectrometry, and the irradiance (mW/cm(2)) was calculated from the tip area of each LCU. The minimum acceptable irradiance outputs for the quartz-tungsten-halogen (QTH) and light-emitting diode (LED) units were set at 300 and 600 mW/cm(2), respectively. The ages of these units and the protocol used to light-cure the resins were also determined. RESULTS: The total number of LCUs was 140, 112 (78%) in urban areas, and 28 (22%) in rural areas. In rural areas, only 7 of the 22 (32%) QTH units delivered irradiances greater than 300 mW/cm(2) and were therefore considered clinically acceptable, whereas 4 of the 6 (66.7%) LED units delivered values greater than 600 mW/cm(2). In urban centers, 43 of 61 (70.5%) LED units and 25 of 61 (49%) QTH units were considered clinically acceptable. Irradiance values for both QTH (P < 0.01) and LED (P < 0.05) units were significantly better in urban than in rural areas. CONCLUSIONS: Urban areas had a greater distribution of LCUs than rural areas. Overall, irradiance values were significantly higher in urban areas.

10.
J Contemp Dent Pract ; 12(5): 327-32, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-22269191

RESUMO

UNLABELLED: Learning fine motor skills is a pre-requisite for succeeding in dental practice and it is sometimes challenging for dental students. Most of the methods used in the selection process depend on evaluation of intellectual ability or structured interview while manual competence is not. However, no test on aptitude or manual dexterity is used as criteria. OBJECTIVE: The purpose of the present study intended to evaluate the fine motor skills of beginning dental students which could in turn be used as a method of selection of students for the dental degree admission process. MATERIALS AND METHODS: A study was conducted among 71 second year dental students at College of Dentistry, King Saud University in Riyadh. A test composed of three parts, writing an answer for a question in four lines, drawing a picture of a smile and doing a class 1 amalgam preparation on a plastic molar tooth. The students were evaluated based on their handwriting, basic drawing skills and their skills in performing the tooth preparation by experts in each fields following certain criteria. RESULTS: The results showed a significant correlation between writing and drawing skills and dental skills of the student with p < 0.001. CONCLUSIONS: The results of the current study support the use of the writing or drawing test as one of the test used for the applicants for dental school admission. However, the value given to such test in the selection of students needs further investigations and consensus.


Assuntos
Arte , Escrita Manual , Destreza Motora/fisiologia , Estudantes de Odontologia , Aptidão/classificação , Amálgama Dentário , Preparo da Cavidade Dentária/classificação , Preparo da Cavidade Dentária/instrumentação , Equipamentos Odontológicos de Alta Rotação , Humanos , Masculino , Dente Molar/anatomia & histologia , Arábia Saudita , Critérios de Admissão Escolar , Adulto Jovem
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