Addition of metal chlorides to a HOCl conditioner can enhance bond strength to smear layer deproteinized dentin

Kittisak Sanon, Antonin Tichy, Takashi Hatayama, Ornnicha Thanatvarakorn, Taweesak Prasansuttiporn, Takahiro Wada, Yasushi Shimada, Keiichi Hosaka, Masatoshi Nakajima

Research output: Contribution to journalArticlepeer-review


Objectives: To evaluate the effect of smear layer deproteinization using hypochlorous acid (HOCl) with/without metal chlorides (SrCl2 and ZnCl2) on the microtensile bond strength (µTBS) of two simplified adhesives to dentin. Methods: Human dentin surfaces with a standardized smear layer were pretreated using a 105 ppm HOCl solution with/without SrCl2 (0.05 M, 0.1 M, 0.2 M, 0.4 M) or ZnCl2 (0.05 M, 0.1 M, 0.2 M) for 5 s, 15 s, or 30 s. After the deproteinizing solution was washed out with water for 5 s, 15 s, or 30 s, pretreated surfaces were bonded with one-step self-etch adhesive Bond Force II or universal adhesive Clearfil Universal Bond Quick, and µTBS was measured after 24 h. Additionally, the deproteinizing effects of HOCl solutions with/without the metal chlorides were compared by measuring changes in the amide:phosphate ratio using attenuated total reflection Fourier transform infrared spectroscopy. Statistical analysis was performed using multifactor ANOVA, Tukey's post hoc tests and t-tests (p < 0.05). Results: Pretreatment with pure HOCl for 15 s and 30 s significantly decreased the amide:phosphate ratio (p < 0.05), indicating effective deproteinization, but the µTBS of both adhesives increased significantly only if HOCl was washed out for 30 s (p < 0.05). Increasing the concentrations of metal chlorides enabled shortening of the wash-out time down to 5 s while maintaining the improved µTBS (p < 0.05). The deproteinizing effect of HOCl was not significantly altered by the addition of metal chlorides (p > 0.05).

Original languageEnglish
JournalDental Materials
Publication statusAccepted/In press - 2022


  • Adhesion
  • FTIR
  • Hypochlorous acid
  • Microtensile bond strength
  • Pretreatment
  • Smear layer deproteinization
  • Strontium chloride
  • Zinc chloride

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials


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