title: Effect of intracanal medicaments used in endodontic regeneration procedures on microhardness and chemical structure of dentin.
abstract: OBJECTIVE
  This study was performed to investigate the effects of different intracanal medicaments on chemical structure and microhardness of dentin.
  
  
  METHODS
  Fifty human dentin discs were obtained from intact third molars and randomly assigned into two control groups and three treatment groups. The first control group received no treatment. The second control group (no medicament group) was irrigated with sodium hypochlorite (NaOCl), stored in humid environment for four weeks and then irrigated with ethylenediaminetetraacetic acid (EDTA). The three treatment groups were irrigated with NaOCl, treated for four weeks with either 1 g/mL triple antibiotic paste (TAP), 1 mg/mL methylcellulose-based triple antibiotic paste (DTAP), or calcium hydroxide [Ca(OH)2] and finally irrigated with EDTA. After treatment, one half of each dentin disc was subjected to Vickers microhardness (n = 10 per group) and the other half was used to evaluate the chemical structure (phosphate/amide I ratio) of treated dentin utilizing attenuated total reflection Fourier transform infrared spectroscopy (n = 5 per group). One-way ANOVA followed by Fisher's least significant difference were used for statistical analyses.
  
  
  RESULTS
  Dentin discs treated with different intracanal medicaments and those treated with NaOCl + EDTA showed significant reduction in microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.05) compared to no treatment control dentin. Furthermore, dentin discs treated with TAP had significantly lower microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.0001) compared to all other groups.
  
  
  CONCLUSIONS
  The use of DTAP or Ca(OH)2 medicaments during endodontic regeneration may cause significantly less microhardness reduction and superficial demineralization of dentin compared to the use of TAP.
authors.affiliation: Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Ghaeth Hamdon
authors.initials: GH
authors.lastname: Yassen
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: George Joseph
authors.initials: GJ
authors.lastname: Eckert
authors.affiliation: Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University School of Dentistry, Indianapolis, IN, USA.
authors.forename: Jeffrey Allen
authors.initials: JA
authors.lastname: Platt
keywords: Calcium hydroxide; EDTA; Endodontic regeneration; FTIR; Microhardness; Triple antibiotic paste