Ability of Six Curing Lights to Photocure Four Resin-Based Composites in a MOD-Mold: A Double-Blind Study.

OBJECTIVE: The ability of six curing lights to photocure four resin-based composites (RBCs) in a mold simulating a cavity was compared visually. MATERIALS AND METHODS: Four RBCs were photocured using the: Woodpecker B for 2x10s, SmartLite Pro 2x10s, Valo Cordless 2x10s, Valo Cordless 2x3s Xtra power, Valo X 2x10s, Valo X 2x5s Xtra power, PowerCure 2x3s mode, Monet 1x1s and Monet 3x1s, in a mold representing a molar Class II restoration. Immediately after photocuring, the RBC specimens were immersed in a solvent to remove the uncured RBC, after which they were photographed and de-identified. Using a REDCap survey, these images were compared visually to compare the ability of the LCUs to photocure the restorations. RESULTS: There were significant differences in how well the LCUs had photocured the RBCs. The SmartLite Pro and Valo X used for two 10s exposures produced restorations rated as the best cured, and the Monet used for 1 s was rated the worst. CONCLUSIONS: There were visually apparent differences in how well the LCUs could photocure the RBCs. The Monet used for 1 second produced the worst results for all four RBCs.

Monowave vs. Polywave Light - Curing Units: Effect on Light Transmission of Composite without Alternative Photoinitiators.

Objective: The aim of this study was to compare the light transmission of monowave and polywave-curing devices by a bulk-fill composite containing only camphorquinone as a photoinitiator. Materials and methods: Three light-curing devices were used to cure bulk-fill composite QuiXfil: one monowave (Translux® Wave) and two polywave (VALO Cordless and Bluephase® PowerCure. The NIST-calibrated spectrometer (MARC Resin Calibrator, BlueLight Analytics Inc.) was used to measure the incident and transmitted light through a 2-mm composite specimen over 20 s. Light transmittance was calculated from the ratio of the amount of transmitted and incident light. For data analysis (ANOVA, α = 0.05), total irradiation of the entire spectrum, irradiation with wavelengths of 360-420 nm for the violet spectrum, and 420-540 nm for the blue spectrum were selected. Results: Monowave curing unit Translux® Wave had the lowest light transmission (13.78 ± 0.5%), similar to the violet light transmission of polywave devices (12.02 ± 0.94% and 13.81 ± 1.72% for Valo Cordless and Bluephase PowerCure, respectively). Blue light transmittance (32.15-23.70%) was more than twofold higher than for the wavelengths in the violet region of the spectrum (13.81-12.02%) for the two polywave devices. VALO Cordless showed the highest total and blue light transmission (p<0.001). There was no significant difference in the transmission of the violet part of the spectrum between VALO Cordless and Bluephase® PowerCure (p = 0.465). Conclusion: Within the limitations of this study, we could conclude that polywave curing devices can be used for the polymerization of the bulk-fill composite with camphorquinone as the sole photoinitiator.

Thermography and conversion of fast-cure composite photocured with quad-wave and laser curing lights compared to a conventional curing light.

OBJECTIVES: This study investigated effects of the different emittance-mode protocols from three light curing units (LCUs): (i) a Laser (Monet); (ii) a quad-wave (PinkWave); (iii) a conventional LED (Elipar S10) on the temperature rise (ΔT) and degree of conversion (DC) when photo-curing fast or conventional bulk-fill resin-based composites (RBC). The aim was to correlate ΔT and DC, and the radiant exposure delivered to RBC specimens. METHODS: A 3D-printed resin mold of 4 mm depth was filled with two bulk-fill RBCs: Tetric PowerFill® (fast photo-polymerised composite) (TPF) or Tetric EvoCeram® Bulk-Fill (EVO). Three LCUs were used: (i) Monet laser for 1 s and 3 s (MONET-1 s, MONET-3 s); (ii) PinkWave quad-wave used for 3 s in Boost mode (PW-3 s) and for 20 s in standard mode (PW-20 s); (iii) Elipar S10 for 5 s (S10-5 s) and for 20 s in standard mode (S10-20 s). 2-dimensional temperature maps were obtained before, during and for 60 s after the LCU had turned off using a thermal imaging camera. Thermal changes were analysed at five depths: (0, 1, 2, 3, and 4 mm from the top surface of the RBC). The maximum temperature rise (Tmax) and the mean temperature rise (ΔT) were determined. Cylindrical-shaped specimens were prepared from each material using a stainless-steel split mold (4 × 4 mm) and light-cured with the same protocols. The DC was measured for 120 s and at 1 h after LCU had turned off using Fourier Transform Infrared Spectroscopy (FTIR). Data were analysed using Three-way ANOVA, One-way ANOVA, independent t-tests, and Tukey post-hoc tests (p < 0.05). RESULTS: Radiant exposures delivered by the various irradiation protocols were between 4.5-30.3 J/cm2. Short exposure times from MONET-1 s and PW-3 s delivered the lowest radiant exposures (4.5 and 5.2 J/cm2, respectively) and produced the lowest ΔT and DC. The longer exposure times in the standard modes of PW-20 s, S10-20 s, and MONET-3 s produced the highest Tmax, ΔT, and DC for both composites. The ΔT range among composites at different depths varied significantly (31.7-49.9 °C). DC of TPF ranged between 30-65% and in EVO between 15.3-56%. TPF had higher Tmax, ΔT for all depths and DC compared to EVO, across the LCU protocols (p < 0.05), except for PW-20 s and MONET-3 s. The coronal part of the restorations (1-2 mm) had the highest ΔT. There was a positive correlation between ΔT and DC at 4-mm depth after 120 s SIGNIFICANCE: Longer, or standard, exposure times of the LCUs delivered greater radiant exposures and had higher DC and ΔT compared to shorter or high-irradiance protocols. The fast photo-polymerised RBC had comparatively superior thermal and conversion outcomes when it received a high irradiance for a short time (1-5 s) compared to the conventional Bulk-Fill RBC.

Irradiance from 12 LED light curing units measured using 5 brands of dental radiometers.

OBJECTIVE: To evaluate the accuracy of five brands of radiometers in reporting the irradiance (mW/cm2 ) from twelve brands of LCUs compared to a 'Gold Standard' (GS) reference obtained from a hand-held laboratory-grade radiometer. MATERIALS AND METHODS: The irradiance was measured from two examples of twelve brands of previously used LCUs on two examples of five brands of dental radiometers. The emission spectrum was also obtained. Irradiance data from each brand of LCU against each meter was analyzed using the Shapiro-Wilk test for normality. The irradiance values were subjected to a two-way ANOVA followed by Bonferroni tests for each LCU brand. Finally, a descriptive analysis was made using a 95% confidence interval around the mean irradiance. RESULTS: The power output from the LCUs ranged from 271 mW to 1005 mW. Among the tested radiometers, only the Bluephase Meter II could accurately report the irradiance from 11 out of the 12 brands of LCU evaluated in this study. When measured using the "GS" system, the mean irradiance values from the two examples of nine brands of previously used LCU were not always within ±10% of the irradiance values stated by the manufacturer. CONCLUSIONS: The mean irradiance values from 9 of the 12 brands of used LCUs were beyond ±10% of the irradiance values stated by the manufacturer. Only the Bluephase Meter II could accurately report the irradiance from 11 out of the 12 brands of LCU evaluated in this study. CLINICAL SIGNIFICANCE: There was a wide range in the power output from the LCUs tested. It was impossible to accurately measure the irradiance from all the LCUs using the dental radiometers examined. However, dental radiometers should still be used in dental offices to monitor the light output from LCUs and verify that they are working correctly before they are used on patients.

Ability of short exposures from laser and quad-wave curing lights to photo-cure bulk-fill resin-based composites.

OBJECTIVE: This study investigated the ability of a laser, and a 'quad-wave' LCU, to photo-cure paste and flowable bulk-fill resin-based composites (RBCs). METHODS: Five LCUs and nine exposure conditions were used. The laser LCU (Monet) used for 1 s and 3 s, the quad-wave LCU (PinkWave) used for 3 s in the Boost and 20 s in the Standard modes, the the multi-peak LCU (Valo X) used for 5 s in the Xtra and 20 s in the Standard modes, were compared to the polywave PowerCure used in the 3 s mode and for 20 s in the Standard mode, and to the mono-peak SmartLite Pro used for 20 s. Two paste consistency bulk-fill RBCs: Filtek One Bulk Fill Shade A2 (3 M), Tetric PowerFill Shade IVA (Ivoclar Vivadent), and two flowable RBCs: Filtek Bulk Fill Flowable Shade A2 (3 M), Tetric PowerFlow Shade IVA (Ivoclar Vivadent) were photo-cured in 4-mm deep x 4-mm diameter metal molds. The light received by these specimens was measured using a spectrometer (Flame-T, Ocean Insight), and the radiant exposure delivered to the top surface of the RBCs was mapped. The immediate degree of conversion (DC) at the bottom, and the 24-hour Vickers Hardness (VH) at the top and bottom of the RBCs were measured and compared. RESULTS: The irradiance received by the 4-mm diameter specimens ranged from 1035 mW/cm2 (SmartLite Pro) to 5303 mW/cm2 (Monet). The radiant exposures between 350 and 500 nm delivered to the top surface of the RBCs ranged from 5.3 J/cm2 (Monet in 1 s) to 26.4 J/cm2 (Valo X), although the PinkWave delivered 32.1 J/cm2 in 20 s 350 to 900 nm. All four RBCs achieved their maximum DC and VH values at the bottom when photo-cured for 20 s. The Monet used for 1 s and the PinkWave used for 3 s on the Boost setting delivered the lowest radiant exposures between 420 and 500 nm (5.3 J/cm2 and 3.5 J/cm2 respectively), and they produced the lowest DC and VH values. CONCLUSIONS: Despite delivering a high irradiance, the short 1 or 3-s exposures delivered less energy to the RBC than 20-s exposures from LCUs that deliver> 1000 mW/cm2. There was an excellent linear correlation (r > 0.98) between the DC and the VH at the bottom. There was a logarithmic relationship between the DC and the radiant exposure (Pearson's r = 0.87-97) and between the VH and the radiant exposure (Pearson's r = 0.92-0.96) delivered in the 420-500 nm range.

In-vitro pulpal temperature increases when photo-curing bulk-fill resin-based composites using laser or light-emitting diode light curing units.

OBJECTIVE: To evaluate the in vitro pulpal temperature rise (ΔT) within the pulp chamber when low- and high-viscosity bulk-fill resin composites are photo-cured using laser or contemporary light curing units (LCUs). MATERIALS AND METHODS: The light output from five LCUs was measured. Non-retentive Class I and V cavities were prepared in one upper molar. Two T-type thermocouples were inserted into the pulp chamber. After the PT values reached 32°C under simulated pulp flow (0.026 mL/min), both cavities were restored with: Filtek One Bulk Fill (3 M), Filtek Bulk Fill Flow (3 M), Tetric PowerFill (Ivoclar Vivadent), or Tetric PowerFlow (Ivoclar Vivadent). The tooth was exposed as follows: Monet Laser (1 and 3 s), PowerCure (3 and 20 s), PinkWave (3 and 20 s), Valo X (5 and 20 s) and SmartLite Pro (20 s). The ΔT data were subjected to one-way ANOVA followed by Scheffe's post hoc test. RESULTS: Monet 1 s (1.9 J) and PinkWave 20 s (30.1 J) delivered the least and the highest amount of energy, respectively. Valo X and PinkWave used for 20 s produced the highest ΔT values (3.4-4.1°C). Monet 1 s, PinkWave 3 s, PowerCure 3 s (except FB-Flow) and Monet 3 s for FB-One and TP-Fill produced the lowest ΔT values (0.9-1.7°C). No significant differences were found among composites. CONCLUSIONS: Short 1- to 3-s exposures produced acceptable temperature rises, regardless of the composite. CLINICAL SIGNIFICANCE: The energy delivered to the tooth by the LCUs affects the temperature rise inside the pulp. The short 1-3 s exposure times used in this study delivered the least amount of energy and produced a lower temperature rise. However, the RBC may not have received sufficient energy to be adequately photo-cured.

Novel chairside spectrometer-trained system for measuring the irradiance of light-curing units.

The purpose of this study was to compare the performances of 5 different instruments in measuring the irradiance of light-curing units (LCUs). A novel spectrometer-trained radiometer (CheckUp), 2 conventional chairside radiometers (Bluephase Meter I and Bluephase Meter II), and 2 devices considered to be gold standards for measuring irradiance (an integrating sphere spectrometer and a thermopile sensor) were used to evaluate 7 LCUs. The irradiance of each LCU was measured 10 times with each meter. Data were analyzed using linear regression analysis and a 1-way analysis of variance with Tukey post hoc test (α = 0.05). The mean irradiance values of the LCUs differed significantly depending on which meter was used for measurement (P < 0.05). Bivariate regression analysis demonstrated that the highest correlations in the irradiance values were found between the CheckUp meter and both the integrating sphere (r2 = 0.980) and the thermopile (r2 = 0.933). The absolute mean (SD) percentage deviation between irradiance measured by the CheckUp instrument and irradiance measured by the other meters was 7.2% (2.0%) for the integrating sphere, 7.0% (3.6%) for the thermopile, 21.5% (16.1%) for Bluephase Meter I, and 13.1% (7.1%) for Bluephase Meter II. Compared with the 2 conventional chairside radiometers, the CheckUp meter provided the highest correlation with and lowest absolute percentage deviation from the irradiance measured by the gold standard spectrometers.

Effect of thickness of CAD/CAM materials on light transmission and resin cement polymerization using a blue light-emitting diode light-curing unit.

OBJECTIVE: Evaluate the effect of thickness of high-translucency (HT) CAD/CAM materials on irradiance and beam profile from a blue light-emitting diode light-curing unit (LCU) and on the degree of conversion (DC) and maximum polymerization rate (Rpmax ) of a light-cured resin cement (LCC). MATERIAL AND METHODS: The direct output from the LCU, the light transmission and irradiance ratio (IR) through one conventional composite and nine HT CAD/CAM materials (0.5, 1.0, 1.5, or 2.0-mm thick; n = 5) were measured with a integrating sphere coupled to a spectrometer. The light beam was assessed with a beam profiler camera. The DC at 600 s and the Rpmax of one LCC was determined using a Fourier transform infrared spectrometer (n = 5). Data were analyzed by ANOVA followed by Tukey's tests, and Dunnett's test was also used for irradiance data (α = 0.05). RESULTS: A significant decrease in irradiance through all materials occurred as thickness increased. Thin CAD/CAM materials improved light homogeneity, which decreased with the increase in thickness. The DC of the LCC directly exposed to light was the same as when exposed to 45%, 25%, 15%, or 5% IRs. Rpmax decreased with the decrease in IR. CONCLUSIONS: Although the HT CAD/CAM materials reduced the irradiance from the LCU, minor effects were observed in the LCC's DC. CLINICAL SIGNIFICANCE: Despite the light attenuation of blue light through different CAD/CAM materials that were up to 2-mm thick, the degree of conversion of one brand of light-cured resin cement was clinically acceptable when the LCU was used for 30 s.

In vitro temperature changes in the pulp chamber caused by laser and Quadwave LED-light curing units.

The study evaluated the pulp temperature (PT) increase in Class I and V preparations when exposed to the Monet Laser (for 1 and 3 s), the PinkWave (for 3 and 10 s), the Valo Grand (for 3 and 10 s), the PowerCure, (for 3 and 10 s) and the SmartLite Pro (for 10 s). Non-retentive Class I and Class V cavities were prepared in one molar fixed in an acrylic plate and positioned in a warm water bath. The PT baseline was kept at 32 °C to simulate physiological conditions. Two T-type thermocouples were inserted through the roots into the pulp chamber in two positions: close to the pulp horn and the buccal wall close to the Class V cavity. The water flow was adjusted to 0.026 mL/min, and real-time temperature data were collected every 0.5 s. PT measurements were made with the tip of the LCU 0 and 6 mm away from the tooth surface. The radiant exitance (mW/cm2) and radiant exposure (J/cm2) were calculated. One-way ANOVA compared the effect of the pulpal flow, and ΔT values were subjected to two-way ANOVA, followed by Scheffe's post hoc tests. The Monet Laser used for 3 s and the PinkWave used for 10 s produced the greatest PT rise in the Class I cavity. The simulated pulpal flow did not influence the PT rise. Overall, cavities exposed at the 0 mm distance had higher ΔT values than groups at 6 mm distance. The placement of a rubber dam for Class V restorations may prevent positioning LCUs directly over the cavity, which may affect the rise in PT.

Temperature changes and hardness of resin-based composites light-cured with laser diode or light-emitting diode curing lights.

The temperature and Vickers Hardness (VH) at the top and bottom surfaces of three resin-based composites (RBCs) were measured when light-cured using five light-curing units (LCUs). The spectrum, power, and energy delivered to the top of the RBCs and transmitted through the RBCs were measured. Starting at 32℃, the temperature rise produced by the Monet Laser (ML-1 s and 3 s), Valo Grand (VG-3 s and 10 s), DeepCure (DC-10 s), PowerCure, (PC-3 s and 10 s) and PinkWave (PW-10 s) were measured at the bottom of specimens 2 mm deep × 6 mm wide made of Filtek Universal A2, Tetric Evoceram A2 and an experimental RBC codenamed Transcend UB. The VH values measured at the top and bottom of these RBCs were analyzed using ANOVA and Scheffe's post hoc test (p < 0.05) to determine the effects of the LCUs on the RBCs. The transmitted power from the ML was reduced by 77.4% through 2 mm of Filtek Universal, whereas light from PW decreased by only 36.8% through Transcend. The highest temperature increases from the LCU combined with the exothermic reaction occurred for Transcend, and overall, no significant differences were detected between Filtek Universal and Tetric Evoceram (p = 0.9756). Transcend achieved the highest VH values at the top and bottom surfaces. The PinkWave used for 10 s produced the largest temperature increase (20.2℃) in Transcend. The Monet used for 1 s produced the smallest increase (7.8℃) and the lowest bottom:top VH ratios.

Effect of preheated composite resin luting agents on the color of ceramic laminates.

This in vitro study evaluated the effects of preheating, ultrasound application, and composite resin luting agent composition on the optical characteristics of feldspar ceramic laminates. The hypothesis was that the optical properties of the ceramic-luting agent-substrate unit would be affected by the composition of the luting material and use of ultrasound. Preheated restorative composite resins Charisma, IPS Empress Direct, and Filtek Z350 were used, with unheated RelyX Veneer resin cement serving as the control. The response variables for the physical properties of the materials were degree of conversion (n = 3 per material) and viscosity (n = 3 per material). Seven groups were generated based on the tested luting agent and the use of ultrasound. Color parameters were evaluated with a spectrophotometer at 3 timepoints (before luting [baseline], 24 hours after luting, and 1 month after luting), and color change was calculated according to the Commission Internationale de l'Eclairage (CIE) CIEDE 2000 formula and translucency parameters. The statistical significance of color change and viscosity was measured using 2-way analysis of variance (ANOVA), while the degree of conversion was measured using 1-way ANOVA. For translucency parameters, ANOVA on ranks and post hoc Duncan multiple range tests were performed. The control group showed the highest degree of conversion, while Filtek Z350 showed the highest viscosity. Statistically significant differences in color change between luting material groups were found under most conditions (P < 0.001), but there was no difference in translucency parameters between the luting materials (P = 0.446). Overall, the use of preheated composite resins as luting agents offers similar to poorer performance than conventional resin cement.

Effects of polyvinyl chloride film and oxygen-blocking gel on irradiance and depth of cure.

This study aimed to analyze the effects of polyvinyl chloride (PVC) film and oxygen-blocking gel (OBG) on the irradiance from an LED source and the depth of cure of a composite resin. Irradiance was measured with a curing radiometer, and curing depth was evaluated according to the methods described by the International Organization for Standardization (ISO 4049). Twelve experimental conditions were investigated in a 3 × 4 factorial design (n = 5 specimens per condition): no PVC film at the tip of the device, fitted PVC film, or misfit PVC film; and no OBG or a 1-, 2-, or 3-mm-thick layer of OBG. The data were analyzed using analysis of variance and Tukey tests (P < 0.05), and a linear regression test was performed between the variables (P < 0.05). The analyses showed that the variables under study influenced the irradiance (P < 0.05) but not the curing depth (P > 0.05). The 3 groups that did not have the PVC film and either did not have the OBG or had the OBG in a thickness of 1 or 2 mm were not significantly different from each other (P > 0.05) but presented the highest irradiance values among all the groups (P < 0.05). The use of the misfit PVC film with a 3-mm layer of OBG led to the lowest irradiance values (P < 0.05). The variables did not influence each other (P > 0.05). The results of this study indicated that the presence of PVC film, especially misfit film, reduced the irradiance. In addition, the greater the thickness of the OBG, the lower the irradiance. None of the PVC film barrier conditions or OBG thicknesses had an effect on the depth of cure.

Degree of conversion of resin-cements (light-cured/dual-cured) under different thicknesses of vitreous ceramics: systematic review.

PURPOSE: This systematic review synthesized and analyzed the scientific evidence on the degree of conversion (DC) obtained by Fourier-transform infrared spectroscopy (FTIR) of light-cured and dual-cured resinous cements, photopolymerized under different thicknesses of vitreous ceramics. STUDY SELECTION: The study protocol of this systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42017069319). A comprehensive search (PubMed/MEDLINE, Scopus, EMBASE, and LILACS) was performed for papers including an in vitro design and indexed from January 2007 to December 2020 according to the study purposes. A quality appraisal (specific instrument) and descriptive analysis of the articles that met the inclusion criteria were conducted. RESULTS: Nine included studies were analyzed. Two of them used feldspathic ceramics, six used lithium disilicate, and one used both (comparing different types and opacities of ceramics). Three studies found a higher DC in dual cements, while one did not find any significant differences, and five studies found a higher DC in light-cured resin cements. Light-cured cements showed a better DC in relation to dual-cured cements in vitreous ceramic restorations with thicknesses up to 2 mm. CONCLUSION: According to the findings, the use of good photoactivation is the most relevant variable to achieve an adequate DC in light-cured and dual-cured resin cements. The use of vitreous ceramic restorations with a thickness of less than 2 mm (light-curing cements) shows a better DC. Standardized in vitro studies are required to generate accurate scientific evidence.

[Light-curing effectiveness using led lamps: a review]. / Efectividad de fotopolimerización usando lámparas led: una revisión.

Introduction: LED lamps have a new light-curing technology which can be monowave or polywave, which allows it to reach more initiators such as camphorquinone, Lucirin TPO and Propanodione, which have a wide variety of advantages and disadvantages. These lamps have evolved over time, as have different ergonomics, longevity, systems and quality standards. Objective: The objective of this literature review is to improve the clinician on the proper use of different LED lamps and how they influence the efficiency of resin photopolymerization. Material and methods: Extensive research has been carried out in the existing literature on this topic. From the beginning of this information until April 18, 2022, the bibliographic search carried out includes 86 articles published in the Medline database through PubMed, LILACS, Science Direct and SciELO, and there is no language restriction. Results: The photopolymerization effects of Polywave and Monowave LED lamps present significant differences between the compressive strength of the light-cured resin, with single-wave and polyvalent LED lamps where the types of light and lamp directly influence the compressive strength of the resin. composite resins. Conclusion: The type of light and lamp directly affects the efficiency of the photopolymerization of the composite resin, so it is concluded that LED lamps with single wave technology (Monowave) produce a greater depth of photopolymerization than those with multiple wave technology (Polywave).

Influência de um novo dispositivo acessório de fotopolimerização com fibra óptica e pino de fibra de vidro experimental nas propriedades mecânicas, físicoquímicas e adesão dos cimentos resinosos / Influence of a new light curing device with optical fiber and an experimental glass fiber post on the physicochemical, mechanical properties and adhesion of resin cement

O objetivo deste estudo foi avaliar in vitro a influência de um novo dispositivo fotopolimerização e pino de fibra de vidro nas propriedades mecânicas, físicoquímicas e adesão dos cimentos resinosos. Foram utilizados oitenta dentes bovinos, submetidos ao tratamento endodôntico, distribuídos em 5 grupos (n=16): CD (Pino fibra vidro e cimento dual); PF (Pino perfurado e cimento fotoativado); PD (Pino perfurado e cimento dual); POF (Pino perfurado iluminador de fibra óptica e cimento fotoativado); POD (Pino perfurado iluminador de fibra óptica e cimento dual). Os dentes foram preparados para colocação de um protótipo de pino em fibra de vidro que possui um canal interno de diâmetro regular e com conicidade progressiva. A perfuração permite a inserção da fibra óptica ao longo da extensão do pino a fim de possibilitar a ação da luz ao longo de todo o comprimento do conduto radicular. Após a cimentação, os espécimes foram seccionados perpendicularmente, e obtida 1 fatia de 2 mm de espessura do terço apical, médio e cervical. A avaliação mecânica foi realizada através do ensaio de push-out para determinação da resistência adesiva nos terços cervical, médio e apical seguido pela análise da fratura em estereomicroscópio. Os retentores intrarradiculares foram também submetidos ao teste de flexão de 3 pontos para análise do material preenchedor do pino de fibra (n=10). As análises físico - químicas foram realizadas através da determinação do grau de conversão dos cimentos (RAMAN) e análise em espectroscopia de energia dispersiva (EDS) dos monômeros presentes. A adesão foi analisada pela interface de cimentação pelo MEV e reconstrução 3D do novo sistema através do Micro-CT. Os dados obtidos foram analisados estatisticamente pelo ANOVA (um e dois fatores) e comparação múltipla de Tukey, (p<0,05). Os resultados de resistência adesiva evidenciaram que o terço apical obteve o maior valor de resistência adesiva em comparação ao terço médio (p<0,001), o grupo POD do terço apical foi estatisticamente significante em relação ao grupo CD do terço médio (p<0,001). Na analise individual de cada terço, não houve diferença entre os grupos experimentais e o controle (p>0,05). A falha adesiva entre cimento e dentina foi a mais predominante entre todos os grupos e terços. O pino de fibra de vidro (controle) obteve o maior valor de resistência à flexão (p<0,001), seguido do pino de fibra de vidro perfurado preenchido com cimento resinoso (p<0,001). Os maiores valores de GC foram alcançados pelo grupo POD com 82,3% (cervical) 69,9 % (médio) e 76,21% (apical) e o EDS comprovou a presença de componentes químicos adequados. A análise da adesão do novo pino de fibra de vidro comprova uma excelente adaptação no interior do canal radicular nas regiões cervical, médio e apical. Portanto o novo dispositivo com fibra óptica e pino de fibra de vidro experimental aumentaram as propriedades mecânicas, físico-químicas e adesão do cimento resinoso (AU)

The aim of this study was to evaluate in vitro the influence of a new light curing device with optical fiber and experimental glass fiber post on the physicochemical, mechanical, and adhesion properties of resin cements. Eighty bovine teeth were used, submitted to an endodontic treatment, distributed in 5 groups (n=16): CD (Glass fiber post and dual cement); PF (Perforated post and light-cured cement); PD (Perforated post and dual cement); POF (Fiber optic illuminating with a perforated post and lightcured cement); POD (Fiber optic illuminating with a perforated post and dual cement). The teeth were prepared for placement of a glass fiber post prototype, which has an internal canal of regular diameter and progressive taper. The internal perforation extension allows the insertion of the optical fiber along the entire length of the post in order to allow the action of light along the entire length of the root canal.The specimens were sectioned perpendicularly for the tests, and 1 slice approximately 2 mm thick was obtained from the apical, middle and cervical thirds. The mechanical evaluation was carried out through the push-out test to determine the adhesive bond strength, in the cervical, middle and apical thirds, followed by the fracture analysis under a stereomicroscope, the intraradicular post were also submitted to the 3-point bending test for material analys of the fiber post filler (n=10). The physicochemical analyzes were performed by determining the degree of conversion of the cements (RAMAN) of each sample and the analysis of energy dispersive spectroscopy (EDS) of the monomers present. Adhesion was analyzed by the cementation interface and 3D reconstruction of the new system through micro-CT, and finally, SEM analysis of the adhesive interface. The data obtained were analyzed for normality and statistically by ANOVA (one and two ways) and Tukey's multiple comparison (p<0.05). The adhesive bond strength results showed that the apical third had the highest value of adhesive strength compared to the middle third (p<0.001), and the POD group of the apical third was statistically significant in relation to the CD group of the middle third (p<0.001). In the individual analysis of each third, there was no difference between the experimental and control groups (p>0.05). Adhesive failure between cement and dentin was the most prevalent among all groups and thirds. The conventional post (control) had the highest flexural strength value (p<0.001), followed by the perforated fiberglass post filled with resin cement (p<0.001). The POD group achieved the highest GC values with 82.3% (cervical), 69.9% (medium), and 76.21% (apical) and EDS confirmed the presence of adequate chemical components. The analysis of the adhesion of the new fiberglass post proves an excellent adaptation inside the root canal in the cervical, middle and apical regions. Therefore, the new light curing device with optical fiber and experimental glass fiber post improved the resin cement's mechanical, phycochemical, and adhesion. (AU)

A measurement of irradiance of light-curing units in dental offices in three Croatian cities.

Aim To determine irradiance of light-curing units (LCUs) in dental offices in three Croatian cities and to compare irradiance values with the age and model of LCUs. Methods Private and public dental offices in three most prominent cities in Croatia (Rijeka, Split and Zagreb) were included in this study. In total, 195 LCUs were tested, using radiometer Ivoclar Bluephase Meter 2 for irradiance (mW/cm2 ). The minimum acceptable value was set at 400 mW/cm2 . The age, model and difference between declared and measured irradiance of the LCUs were also determined. Of the total of 195 LCUs, 190 (98%) were LED (light-emitting diode) and 5 (2%) were QTH (quartz-tungsten - halogen). Results The mean age of tested LCUs was 4.43±3.4 years; the oldest was in Rijeka, 5.2±3.8 years. The overall mean irradiance for all three cities was 806.4 mW/cm2 (p=0.0004). Of all LCUs, 11.3% were considered clinically unacceptable with irradiance of less than 400 mW/cm2 . Of all tested LCUs 42% (p=0.0005) had a 30% lower value of irradiance than the manufacturer of the LCU declared. In 73% tested LCUs, there was a matching between measured and declared irradiance. The age and model of LCUs had the most significant impact on irradiance. Conclusion The most commonly used LCU included in dental offices was LED. Mean irradiance was good enough to secure adequate polymerization of resin-based materials. Irradiance decreases with usage time of LCU.

Photodynamic inactivation of Streptococcus mutans by curcumin in combination with EDTA.

OBJECTIVE: This study aimed to test the efficacy of photodynamic inactivation (PDI) mediated by curcumin with EDTA against Streptococcus mutans in planktonic suspension using blue LED light. METHODS: Antibacterial activity of curcumin and EDTA was evaluated by determination of their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of various combination ratios of curcumin and EDTA against S. mutans. Cultures of S. mutans (18 h, 37 °C, 5% C02) were prepared to test the effect of curcumin-mediated PDI (50 µM and 500 µM) with or without 0.4% EDTA and 40 s of light-activation with blue light. EDTA and each concentration of curcumin were also tested individually. Chlorhexidine (0.2%), was used as positive control. Planktonic suspensions were also analyzed by viable colony counts (VCC), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and polymerase chain reaction (PCR). RESULTS: The MIC values of curcumin and EDTA were 5 mM and 0.125% respectively. FICI showed a synergistic interaction between curcumin and EDTA. All the combinations with curcumin and blue LED light resulted in a complete inactivation of the S. mutans and CLSM confirms these results, TEM showed morphological changes produced by the PDI. No damage on DNA structure was detected by PCR. SIGNIFICANCE: Curcumin-mediated PDI with EDTA using a blue light, shows a strong inhibitory effect against S. mutans in planktonic culture. Because of the unspecific target mechanism, it could be a promising technique for disinfection of dental tissues.

Temperatures in the pulpal cavity during orthodontic bonding using an LED light curing unit : An in vitro pilot study.

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.

The light-curing unit: An essential piece of dental equipment.

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.

Effect of flowable composite or glass ionomer liners on shrinkage stress of a composite resin / Efecto de recubrimientos con resinas de baja viscosidad o ionómero vitreo sobre la tensión por contracción de una resina compuesta

ABSTRACT The aim of this study was to evaluate the effect of flowable composite or glass ionomer liners on the shrinkage stress of a restorative composite resin. Fifteen previously sandblasted metal boxes were attached to a universal mechanical testing machine (INSTRON 1011, Instron Corporation). Five of these boxes were filled with Filtek Z350 XT (FXT) Universal Restorative A2 (3M ESPE) (Group 1 or Control). Two further groups of 5 boxes were prepared by interposing a layer of Vitrebond Light Cure Glass Ionomer 3M ESPE (VGI) (Group 2 or G.I.) or Filtek Z350 XT Flowable Restorative A2 3M ESPE (FFR) (Group 3 or Flowable) between the box and the composite resin, completing with the same volume of composite as in Group 1. Upon activating lightcuring, the filled boxes mounted on the testing machine were videoed for 60 seconds (40 s photoactivation and 20 s postcuring), timed with a digital chronometer. Force values were recorded in newtons and converted into stress according to contact surface. Stress values were recorded every 10 s. Results were analyzed using repeated measures ANOVA. Mean and standard deviation in kPa (stress) recorded for each group were: Control group: 126.2 (30.8); G.I.: 48.4 (18); Flowable: 27.9 (19.5). Statistical analysis showed significant differences between the control group and the rest (p<0.01), with no significant difference between groups with glass ionomer liners and flowable resin liners (G.I. and Flowable). Under the experimental conditions of this study, it can be concluded that polymerization shrinkage stress can be reduced by the presence of a liner between the preparation and the restorative material.

RESUMEN El objetivo de este trabajo fue evaluar el efecto de la colocación de una capa de Composite flow o Ionómero vítreo sobre la tensión de contracción de un composite para restauración. Se utilizaron 15 cajas metálicas previamente arenadas y conectadas a la máquina universal para ensayos mecánicos (INSTRON 1011, Instron Corporation). Cinco de estas cajas (G1) se rellenaron con Filtek Z350 XT (FXT) Universal Restorative A2 3M ESPE. Al iniciar la activación de la unidad de curado se comenzaba a registrar con una cámara de video y un cronómetro digital desde el comienzo de la activación de la lámpara hasta 60 s después, registrando los valores post curado durante 20 s. Los valores de fuerza generados por la polimerización fueron registrados en newton de cada 10 s para los 15 ensayos. Los valores fueron convertidos en tensión de contracción según la superficie de contacto. Se realizaron además dos grupos de cajas (5 en cada una) en los cuales se colocaron una capa inicial de Vitrebond Light Cure Glass Ionomer 3M ESPE (VGI) (G2 o IV) y Filtek Z350 XT Flowable Restorative A2 3M ESPE (FFR) (G3 o Flow) y se completó con el mismo volumen de composite de las del GI. Los resultados obtenidos fueron analizados por medio de ANOVA para mediciones repetidas. La media y la desviación estándar en kPa (tensión o estrés de contracción) registrado para cada grupo fueron: Grupo control: 126.2 (30.8); IV: 48.4(18); Flow: 27.9(19.5). El análisis estadístico mostró diferencias estadística mente significativas entre el grupo control y el resto (p=0.00), pero no hubo diferencias significativas entre la presencia de Ionómero vítreo o Composite Flow (IV y Flow). En las condiciones experimentales de este trabajo puede concluirse que la tensión de contracción generada durante la polimerización puede ser disminuida por la presencia de algún material interpuesto entre la preparación y el composite restaurador.