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Dental Science: Scientific Information Translux® 2Wave Pulp temperature during polymerisation – Georgia Regents University, Augusta, USA In vitro intrapulpal temperature rise of 2 new LED lights. Dental light curing materials can unfold their optimum material properties (e. g. mechanical strength, bond strength, biocompatibility) only when they are polymerised sufficiently. Many factors during the light curing are influencing the polymerisation result. Apart from the light curing technique and material-related conditions, the curing light itself has an impact on the polymerisation result. When selecting a light curing unit it is from vital importance to make sure that it fits to the dental material which needs to be cured. A pre-condition for this is that the light needs to emit light in the wavelength range of the sensitivity of the photoinitiators used in the material. Further the irradiance (the light output related to the area) needs to be high enough to activate the photoinitiators. But the irradiance of curing lights can only be increased to a certain limit. A greater potential risk for heat-induced pulp damage might be associated with high-power LED sources1. Curing devices with high power density (> 1200 mW/cm²) should only be activated for a short period of time2. Finally, the output of the curing unit needs to be checked regularly to ensure that a sufficient polymerisation is possible. The following study performed by Prof. Rueggeberg of the Georgia Regents University demonstrates the low pulp temperature increase the Translux 2Wave develops during curing. Further, it shows that the wavelength spectrum fits to the camphorquinone photoinitiator which is mainly used in dental light curing composites. Due to its additional violet LED die the Translux 2Wave activates also photoinitiators which require lower wavelengths like e. g. PPD, TPO or TPO-L. Giving a hand to oral health. Pulp temperature during polymerisation – Georgia Regents University, Augusta, USA In vitro intrapulpal temperature rise of 2 new LED lights. Objective This project will measure and compare the in vitro intrapulpal temperature rise when exposing an empty, 4-mm deep, Class I preparation in an extracted, human molar to a variety of LED-based dental light curing units. Further, the spectral irradiance was measured, and the total energy output was calculated and reported. Materials & Methods The tested light curing units were: Translux Wave and Translux 2Wave (both Heraeus Kulzer), S.P.E.C.3 (Colténe/Whaledent), Bluephase Style (Ivoclar Vivadent) and Elipar S10 (3M ESPE). The Translux Wave, Translux 2Wave, Bluephase Style and Elipar S10 were used in the standard mode for 20bs, whereas the S.P.E.C.3 was used in the 3K mode for 2 x 3bs. The roots of an extracted human molar were shortened. The pulp was extirpated and tubing was then cemented to the roots. A section of tubing was connected to one tube end and a portion of the remaining end was coiled to increase surface area in contact with the warmed water in which it was immersed. The distal end of the tubing was connected to a water-filled, glass syringe simulating physiological fluid flow. 2 mm THERMOCOUPLE LEADS TO DIGITAL INTERFACE 6 mm LIGHT LIGHT CURING CURING TIP 4 mm SOLAR CELL TO MONITOR CURING LIGHT ACTIVATION RESERVIOR RESERVOIR AND OVERFLOW OVERFLOW MOTOR-DRIVEN SYRINGE PLASTIC PLATE TEMPERATURE TEMPERATURE CONTROLLED CONTROLLED WATER WATER BATH BATH THERMOCOUPLE TO MONITOR WATER BATH TEMPERATURE OUTLET OUTLET INLET INLET ERLENMEYER ERLENMEYER FLASK FLASK WARMING WARMING COIL COIL Depiction of test set-up used for measuring simulated intrapulpal temperatures A thermocouple was positioned so that it rested directly against the coronal pulpal wall opposite the pulpal floor of a Class I preparation made in the tooth. The thermocouple output was connected to a computer. The software both visually displayed and digitally recorded the thermocouple temperature in real-time at a rate of 10 data points per second. A solar cell helped to determine the exact time when the light unit was activated and deactivated. The roots of the prepared tooth were placed through an opening of a plastic plate that covered the top of the Erlenmeyer flask. The flask itself rested in water of a temperature-controlled bath (Thermo-Lift, Model I-2000, Buchler Instruments, Inc., Fort Lee, NJ). Water temperature was thermostatically controlled to provide an intrapulpal temperature of approximately 35b°C (± 0.5b°), which is similar to that of the in vivo condition. The average real-time time-temperature plot developed from performing five separate replications of exposure for each light unit were obtained. Statistical analysis of temperature values obtained at the desired exposure durations was obtained using a 1-way analysis of variance. If that test indicated statistical significance, the Tukey post-hoc, pair-wise means comparison test was performed. All statistical testing was performed at a pre-set alpha of 0.05. The spectral irradiance was measured (n = 5) using an integrating sphere which was connected to a spectroradiometer, the output of which was fed to a software on a personal computer. In order to calculate irradiance, the emitting area at the tip end was calculated using the beam profiling device. The emitted beam diameter from that analysis was then used to divide the calculated power values into units of irradiance. 1 2 Baroudi K, Silikas N, Watts DC: In vitro pulp chamber temperature rise from irradiation and exotherm of flowable composites. Int J Paediatr Dent, 19,1, 2009:48-54. Park S-H, Roulet J-F, Heintze SD: Parameters influencing increase in pulp chamber temperature with light-curing devices: curing lights and pulpal flow rates. Oper Dent, 35,3, 2010:353-61. Results Translux 2Wave induces only low temperature change in the pulp Mean intrapulpal temperature [°C] 6 Benchmark treshold for possibly causing pulpal necrosis 5 4 B B A A A Bluephase Style Elipar S10 S.P.E.C.3 (2 x 3bs) Translux Wave Translux 2Wave 3 2 1 0 Similar upper case letters are not statistically significantely different. Irradiance [mW/cm²/nm] Translux 2Wave is matched to camphorquinone and newer violet light activated photoinitiators 10 8 TPO-L 6 4 2 0 350 PPD TPO Emisson Translux® 2Wave Translux 2Wave Bluephase Style CQ 400 450 Wavelength [nm] 500 PPD (1-Phenylpropane-1,2-dione) CQ (Camphorquinone) TPO-L (Ethyl-2,4,6-trimethylbenzoyl-phenylphosphinate) TPO (Diphenyl-2,4,6-trimethyhlbenzoyl-phosphine oxide) Light curing unit Energy density [J/cm²] S.P.E.C.3 (2 x 3bs, ORTHO mode) 22.3 Elipar S10 (20bs) 21.7 Bluephase Style (20bs) 18.7 Translux Wave (20bs) 19.8 Translux 2Wave (20bs) 21.8 From this graph, it indicates that the irradiance of the Translux 2Wave in both the blue and violet spectral regions is similar with respect to wavelength, but the irradiance of the Translux unit exceeds that of the Bluephase Style at both major output regions. Two distinct wavelengths of emission are seen from the Translux 2Wave. The longer, blue wavelength is centered near 460bnm, while the shorter wavelength, violet chip is located near 406bnm. The Translux 2Wave exhibited an irradiance of 1088 ± 9bmW/cm² (measured with integrating sphere + spectroradiometer). When used for a 20-second exposure, the total emitted energy density (irradiance multiplied by exposure duration) of the Translux 2Wave was 21.8bJ/cm². Conclusion In short, intrapulpal temperatures observed using the new Heraeus Kulzer Translux 2Wave was not remarkably different from those of competitive, commercial products. None of the light units exceeded an intrapulpal temperature rise of 5.5b°C, which has been attributed with the presence of pulpal necrosis in rhesus monkeys 3. Source Rueggeberg F: REPORT – In vitro intrapulpal temperature rise of 2 new LED lights, November 2013. Unpublished data. Data on file. The study was abbreviated and summarised and all diagrams and titles have been established by Heraeus Kulzer. Translux is a registered trademark of Heraeus Kulzer. 3 Zach L, Cohen G. Pulp response to externally applied heat. Oral Surgery Oral Medicine and Oral Pathology 19:515-530, 1965. Contact in Germany: Heraeus Kulzer GmbH Grüner Weg 11 63450 Hanau [email protected] www.heraeus-kulzer.de Contact in the United Kingdom: Heraeus Kulzer Ltd Heraeus House Albert Road, Newbury Berkshire, RG14 1DL Phone +44 1635 30500 Fax +44 1635 524622 [email protected] www.heraeus-kulzer.com Contact in Australia & New Zealand: Heraeus Dental Australia Pty Ltd Level 9, Avaya House, 123 Epping Road Macquarie Park NSW 2113 Toll Free: 1800 226521 Phone +61 2 8875-7765 Fax +61 2 9888-1460 [email protected] www.heraeus-kulzer.com heraeus-kulzer.com