title: Laser-induced acoustic emissions in experimental dental composites.
abstract: A laser thermoacoustic technique was innovated to evaluate laser-induced acoustic emissions (AEs) in experimental dental composites aged with 75% ethanol solution. Experimental composite systems of 75/25 BisGMA/TEGDMA resin filled with 0, 12.6, 30.0, and 56.5 vol% of 8-microm silanized and unsilanized BaSiO6 were analyzed. The sample size was 4.65 mm (diameter) x 0.5 mm (thick). Aging effects of immersing in 75% ethanol for up to 14 h on AEs were then evaluated. A continuous-wave CO2 laser was used to heat the samples. Acoustic emissions were collected as a function of filler fraction, laser power, silanization, and immersion time. Onset of burst-pattern acoustic signals characteristic of fracturing occurred at different laser powers for different tested groups. Acoustic emissions generally increased with laser power, in which lower laser powers produced low-amplitude (45-50 dB) signals; the amplitude distribution (50-85 dB) became more extensive as laser powers increased. After immersion, the lower laser powers could produce the same phenomenon. The higher the filler fraction, the fewer AEs generated. A large percentage AE reduction due to silanization was noted as a function of filler fraction. Unsilanized specimens showed more thermal damages than did silanized ones.
authors.affiliation: Graduate Institute of Oral Rehabilitation Sciences, Taipei Medical College, Taiwan. seanlee@tmc.edu.tw
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: C T
authors.initials: CT
authors.lastname: Lin
authors.forename: E S
authors.initials: ES
authors.lastname: Keh
authors.forename: L C
authors.initials: LC
authors.lastname: Pan
authors.forename: H M
authors.initials: HM
authors.lastname: Huang
authors.forename: Y H
authors.initials: YH
authors.lastname: Shih
authors.forename: H C
authors.initials: HC
authors.lastname: Cheng
mesh_terms: D000162:Acoustics; D017609:Barium Compounds / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D004867:Equipment Design; D000431:Ethanol / Q000494:pharmacology; D006358:Hot Temperature; D007101:Immersion; D007834:Lasers; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D008863:Microspheres; D017640:Silicates / Q000737:chemistry*
chemical_list: D017609:Barium Compounds; D003188:Composite Resins; D017640:Silicates; C415406:barium borosilicate; D000431:Ethanol