title: Reducing, by pulse width modulation, the curing temperature of a prototype high-power LED light curing unit.
abstract: Third-generation LEDs have high irradiance and efficiency, but the associated temperature rise is potentially hazardous to the pulp of teeth. We evaluated, during composite polymerization, the irradiance and temperature rise of a prototype high-power LED light curing unit (LCU) with optimal pulse width modulation (PWM), and then compared the results with four off-the-shelf high-power LCUs. A cavity was prepared in a tooth, and a composite resin layer was applied and cured. For each LCU, the irradiance and temperature changes at the pulp-dentin junction were measured. Microhardness (Vickers hardness) of cured composite samples was measured for each LCU. Our prototype had a final temperature of 36.4 +/- 1.3 degrees C and irradiance of 1,182 +/- 1 mW/cm2. The unit with the highest temperature had a temperature of 48.7 +/- 1.2 degrees C and an irradiance of 1,194 +/- 1 mW/cm2. Based on the results of the present study, it was shown that PWM technology reduced the curing temperature while retaining the polymerization effectiveness of a high-power LED LCU.
authors.affiliation: TSAI Graduate Institute of Dental Science, Chung-Ho Memorial Hospital, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan, Republic of China.
authors.forename: Ta-Ko
authors.initials: TK
authors.lastname: Huang
authors.forename: Chun-Cheng
authors.initials: CC
authors.lastname: Hung
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Tsai
mesh_terms: D000704:Analysis of Variance; D001831:Body Temperature; D003188:Composite Resins / Q000528:radiation effects*; D003748:Dental Equipment; D003782:Dental Pulp; D004560:Electricity; D006219:Halogens; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D008027:Light; D044367:Phase Transition; D011791:Quartz; D012666:Semiconductors; D018709:Statistics, Nonparametric
chemical_list: D003188:Composite Resins; C444701:Filtek Z250; D006219:Halogens; D011791:Quartz