Odontological light-emitting diode light-curing unit beam quality (original) (raw)
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PubMed, 2013
Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-hardness (SMH) of dental resin composite. Design: Laboratory based, cross-sectional analytical study. Setting: Public and private dental clinics in Nairobi, Kenya. Subjects: Eighty three LCUs which were in use in private and public dental health facilities in Nairobi, Kenya and resin composite specimens. Results: Of the 83 LCUs studied, 43 (51.8%) were Light Emitting Diodes (LEDs) and 39(47.0%) were Quartz-Tungsten-Halogen (QTH) and 1 (1.2%) was Plasma Arc Curing (PAC) light. Mean light intensity for QTH and LED lights was 526.59 mW/cm2 and 493.67 mW/cm2 respectively (p=0.574), while the mean DOC for QTH lights was 1.71 mm and LED was 1.67 mm (p=0.690). Mean Vickers Hardness Number (VHN) for LED was 57.44 and for QTH was 44.14 (p=0.713). Mean light intensity for LCUs < or = 5 years was 596.03 mW/cm2 and 363.17 mW/cm2 for units > 5 years old (p=0.024). The mean DOC for the two age groups was 1.74 mm and 1.57 mm respectively (p=0.073). For SMH, the < or = 5 years and >5 years age groups gave a mean VHN of 58.81 and 51.46 respectively (p=0.1). On maintenance history, the frequency of routine inspection, duration since the last repair/replacement of a part or other maintenance activity and the nature of the last maintenance activity were determined and were not found to have influenced the light intensity, DOC and SMH. Conclusion: The LCU age has a statistically significant influence on its light intensity (p=0.024) while the type and maintenance history have no significant influence on its light intensity and composite DOC and SMH (p=0.574, p=0.690, p=0.713 respectively).
Comparative Effectiveness of Two Light Curing Units on the Properties of Dental Resin Composites
Pakistan Journal of Medicine and Dentistry, 2020
Background: Setting of conventional glass ionomers cement and dental resin composites as filling materials is predominantly through polymerization reaction, which is usually induced by light. The objective of this study was to assess the temperature changes, light intensities, sorption and solubility capability and comparative micro hardness in Dental Resin Composites (DRC) by using two different light curing units that is Quartz Tungsten Halogen (QTH) and Light Emitting Diodes (LED). Methods: This analytical, experimental, in-vitro study was spanned over one month, conducted in the laboratory of Dental Materials, Dr. Ishrat-ul-Ibad Khan Institute of Oral Health Sciences. Through non-probability, convenient sampling, 60 samples of DRCs was prepared as 10mm in diameter and 2mm in thickness in the steel moulds by a single trained operator. Effect of heat generation, light intensities, sorption and solubility and micro hardness during polymerization of DRCs were all measured. Statistica...
Dental Materials, 2000
Objective: The primary objective of this pilot study was to test the hypotheses that (i) depth of cure and (ii) compressive strength of dental composites cured with either a light emitting diode (LED) based light curing unit (LCU) or a conventional halogen LCU do not differ significantly. The second objective of this study was to characterise irradiance and the emitted light spectra for both LCUs to allow comparisons between the units. Methods: Dental composite (Spectrum TPH, shades A2 and A4) was cured for 40 s with either a commercial halogen LCU or a LED LCU, respectively. The LED LCU uses 27 blue LEDs as the light source. The composites' depth of cure was measured for 10 samples of 4 mm diameter and 8 mm depth for each shade with a penetrometer. The results were compared using a Student's t-test. Compressive strengths were determined after 6 and 72 h, for six samples of 4 mm diameter and 6 mm depth for each shade after being polymerised for 40 s from each end of the mould. Groups were compared using a three way ANOVA. Results: The conventional halogen LCU cured composites significantly p Ͻ 0:05 deeper (6.40 mm A2, 5.19 mm A4) than did the LED LCU (5.33 mm A2, 4.27 mm A4). Both units cured the composite deeper than required by both ISO 4049 and the manufacturer. A three way ANOVA showed that there were no significant differences in the compressive strengths of samples produced with either the LED LCU or the halogen LCU p 0:460: Significant differences in compressive strength of samples stored for 6 and 72 h p 0:0006 and of samples of different shades p 0:035 were found as confirmed by the three way ANOVA. The light spectra of both units differed strongly. While the halogen LCU showed a broad distribution of wavelengths with a power peak at 497 nm, the LED LCU emitted most of the generated light at 465 nm. The LED LCU produced a total irradiance of 350 mW cm Ϫ2 whereas the halogen LCU produced a total irradiance of 755 mW cm Ϫ2. Significance: The results showed that both units provided sufficient output to exceed minimum requirements in terms of composites' depth of cure according to ISO 4049 and the depth of cure and the composites' compressive strength stated by the manufacturer. Compressive strengths of dental composites cured under laboratory conditions with a LED LCU were statistically equivalent to those cured with a conventional halogen LCU. With its inherent advantages, such as a constant power output over the lifetime of the diodes, LED LCUs have great potential to achieve a clinically consistent quality of composite cure.
The Journal of Contemporary Dental Practice, 2012
Purpose To evaluate the curing depth and compressive strength of dental composite using halogen light curing unit and light emitting diode light curing unit. Materials and methods Eighty cylindrical composite specimens were prepared using posterior composite P60(3M). Forty specimens, out of which 20 samples (group A) cured with halogen light and 20 samples (group B) cured using light emitting diode (LED) light were checked for curing depth according to ISO 4049. Remaining 40 samples out of which 20 samples (group I) cured using halogen light and 20 samples (group II) cured using LED light were checked for compressive strength using Instron universal testing machine. Results Twenty samples (group A) cured with halogen light showed better curing depth than 20 samples (group B) cured with LED light. Twenty samples (group I) cured with halogen light showed almost similar results as 20 samples (group II) cured with LED light for compressive strength. Conclusion Halogen light commonly use...
Journal of the Pakistan Medical Association, 2022
Objective: To evaluate the depth of cure in smart dentin replacement bulkfill composite resins polymerized by constant, pulse and ramped light-emitting diode curing modes. Method: The in vitro experimental study was conducted in November and December 2019 at the dental clinics of Aga Khan University Hospital, Karachi, and comprised cylindrical composite specimens 8x4mm in size which were polymerised in Teflon using light-emitting diode under constant mode in Group 1, pulse mode in Group 2 and ramped mode in Group 3. Once polymerised, each specimen was extruded from the mould and, using the International Organisation for Standardisation-4049 scrapping method, uncured resin was removed. Specimen lengths were measured with a Vernier calliper. Each specimen was measured thrice and the mean was taken as the depth of cure. Data was analysed using SPSS 24. Result: Of the 33 specimens, there were 11(33.3%) in each of the 3 groups. Mean depth of cure in Group 1 was 2.92±0.29mm, in Group 2 i...
Curing efficacy of light emitting diodes of dental curing units
Journal of dental research, dental clinics, dental prospects, 2009
The aim of the present study was to compare the efficacy of quartz tungsten halogen (QTH) and light emitting diode (LED) curing lights on polymerization of resin composite. A hybrid resin composite was used to prepare samples which were cured using two QTH and ten LED light curing sources. Twelve groups, each containing ten samples, were prepared using each light source. The cured depth of the resin was determined using ISO 4049 method and Vickers hardness values were determined at 1.0 mm intervals. Data was analyzed by ANOVA and Tukey test. Data analysis demonstrated a significant difference between light sources for depth of cure. At 1.0 mm below the surface all the tested light sources and at 2.0-mm intervals all light sources except two (Optilux 501 and LEDemetron I) and at 3.0-mm intervals only two light sources (PenCure and LEDemetron II) could produce hardness values higher than 80% of superficial layer values. This study showed that a variety of LED light sources used in the...
Journal of Biomedical Materials Research, 2002
The clinical performance of light polymerised dental composites is greatly in#uenced by the quality of the light-curing unit (LCU) used. Commonly used halogen LCUs have some speci"c drawbacks such as decreasing of the light output with time. This may result in low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue-light-emitting diode (LED) LCUs have the potential to polymerise dental composites without having the drawbacks of halogen LCUs. Despite the relatively low irradiance of current LED LCUs, their e$ciency is close to that of conventional halogen LCUs with more than twice the irradiance. This phenomenon has not been explained fully yet. Hence, more tests of the LED LCU's e!ectiveness and of the mechanical properties of oral biomaterials processed with LED LCUs need to be carried out. This study investigates the #exural properties of three di!erent composites with three di!erent shades, which were polymerised with either a commercial halogen LCU or an LED LCU, respectively. In most cases no signi"cant di!erences in #exural strength and modulus between composites polymerised with a halogen LCU or an LED LCU, respectively, were found. A simple model for the curing e!ectiveness based on the convolution absorption spectrum of the camphorquinone photoinitiator present in composites and the emission spectra of the LCUs is presented.
The Effect of Curing Light Intensity on Free Volume Size in Some Dental Composites
Polymers in Medicine
Background. Dental composite resins-reinforced polymers-are types of synthetic resins that are used in dentistry as restorative material or adhesives. The effect of curing-light intensity on free volume sizes of 4 commercial dental composites has been studied by means of the well-known positron annihilation lifetime spectroscopy technique. Objectives. The aim of the study was to compare the photosensitivity of 4 commercial dimethacrylate-based dental composites. Material and Methods. Positron lifetime spectra were collected using a slow-fast coincidence lifetime spectrometer with a time resolution of 365 ps. The positron source was a ~20 µCi 22 Na beta emitter between two 7 µm thick stainless steel foils. The positron source was sandwiched between two identical samples under investigation. The 1 st group of samples was polymerized by a 20-second photo-exposure, and the 2 nd group of samples was irradiated by the blue curing light for 40 s. The positron annihilation lifetime spectrums were separated into components using the PAScual Positron Annihilation Spectroscopy data analysis program. Results. The results showed that the lifetime component associated with free volumes differed in the different composites and depended on the irradiation time. The results indicated that the Coltene composite has higher photosensitivity than the other samples; the Denfil composite exhibited the lowest photosensitivity of the 4. Conclusions. The appropriate light-curing intensity depends on the thickness of the composite, which in turn is proportional to the depth of the hole in the tooth undergoing repair (Polim. Med. 2016, 46, 2, 129-133).