title: Fractography of interface after microtensile bond strength test using swept-source optical coherence tomography.
abstract: To determine the effect of crosshead speed and placement technique on interfacial crack formation in microtensile bond strength (MTBS) test using swept-source optical coherence tomography (SS-OCT).
  
  
  
  MTBS test beams (0.9×0.9mm(2)) were prepared from flat human dentin disks bonded with self-etch adhesive (Clearfil SE Bond, Kuraray) and universal composite (Clearfil AP-X, Kuraray) with or without flowable composite lining (Estelite Flow Quick, Tokuyama). Each beam was scanned under SS-OCT (Santec, Japan) at 1319nm center wavelength before MTBS test was performed at crosshead speed of either 1 or 10mm/min (n=10). The beams were scanned by SS-OCT again to detect and measure cracks at the debonded interface using digital image analysis software. Representative beams were observed under confocal laser scanning microscope to confirm the fractography findings.
  
  
  
  Two-way ANOVA showed that for MTBS the crosshead speed was not a significant factor (p>0.05), while there was a difference between placement techniques (p<0.001), with flowable lining yielding higher mean values. On the other hand, for crack formation, there was a significant difference between crosshead speeds (p<0.01), while the placement technique did not show up as a statistically significant factor (p>0.05). The interaction of factors were not significant (p>0.05).
  
  
  
  Testing MTBS samples at higher crosshead speeds induced more cracks in dentin. Lining with a flowable composite improved the bonding quality and increased the bond strength. SS-OCT can visualize interfacial cracks after restoration debonding.
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Minh Nguyet
authors.initials: MN
authors.lastname: Dao Luong
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: shimada.ope@tmd.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shimada
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan; Operative Dentistry Division, Conservative Dental Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Alaa
authors.initials: A
authors.lastname: Turkistani
authors.affiliation: Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
authors.affiliation: Division of Oral and Dental Surgery, Department of Advanced Medicine, National Center for Geriatrics and Gerontology, National Hospital for Geriatric Medicine, 36-3, Gengo, Morioka, Obu, Aichi 474-8511, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sumi
authors.affiliation: Biomimetics Biomaterials Biophotonics & Technology Laboratory, Department of Restorative Dentistry, University of Washington School of Dentistry, 1959 NE Pacific St. Box 357456, Seattle, WA 98195-7456, USA.
authors.forename: Alireza
authors.initials: A
authors.lastname: Sadr
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D019279:Resin Cements; D013499:Surface Properties; D013718:Tensile Strength; D041623:Tomography, Optical Coherence
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements
keywords: Crosshead speed; Dentin crack; Flowable composite; Fractography; Microtensile bond test; Optical coherence tomography (OCT)