title: Effect of additives on mineral trioxide aggregate setting reaction product formation.
abstract: BACKGROUND
  Mineral trioxide aggregate (MTA) sets via hydration of calcium silicates to yield calcium silicate hydrates and calcium hydroxide (Ca[OH]2). However, a drawback of MTA is its long setting time. Therefore, many additives have been suggested to reduce the setting time. The effect those additives have on setting reaction product formation has been ignored. The objective was to examine the effect additives have on MTA's setting time and setting reaction using differential scanning calorimetry (DSC).
  
  
  METHODS
  MTA powder was prepared with distilled water (control), phosphate buffered saline, 5% calcium chloride (CaCl2), 3% sodium hypochlorite (NaOCl), or lidocaine in a 3:1 mixture and placed in crucibles for DSC evaluation. The setting exothermic reactions were evaluated at 37°C for 8 hours to determine the setting time. Separate samples were stored and evaluated using dynamic DSC scans (37°C→640°C at10°C/min) at 1 day, 1 week, 1 month, and 3 months (n = 9/group/time). Dynamic DSC quantifies the reaction product formed from the amount of heat required to decompose it. Thermographic peaks were integrated to determine enthalpy, which was analyzed with analysis of variance/Tukey test (α = 0.05).
  
  
  RESULTS
  Isothermal DSC identified 2 main exothermal peaks occurring at 44 ± 12 and 343 ± 57 minutes for the control. Only the CaCl2 additive was an accelerant, which was observed by a greater exothermic peak at 101 ± 11 minutes, indicating a decreased setting time. The dynamic DSC scans produced an endothermic peak around 450°C-550°C attributed to Ca(OH)2 decomposition. The use of a few additives (NaOCl and lidocaine) resulted in significantly less Ca(OH)2 product formation.
  
  
  CONCLUSIONS
  DSC was used to discriminate calcium hydroxide formation in MTA mixed with various additives and showed NaOCl and lidocaine are detrimental to MTA reaction product formation, whereas CaCl2 accelerated the reaction.
authors.affiliation: Department of General Dental Sciences-Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, Wisconsin.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Zapf
authors.affiliation: Department of General Dental Sciences-Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, Wisconsin.
authors.forename: Sharath C V
authors.initials: SC
authors.lastname: Chedella
authors.affiliation: Department of General Dental Sciences-Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, Wisconsin. Electronic address: david.berzins@marquette.edu.
authors.forename: David W
authors.initials: DW
authors.lastname: Berzins
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002126:Calcium Hydroxide / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004338:Drug Combinations; D008012:Lidocaine / Q000737:chemistry; D008422:Materials Testing; D010087:Oxides / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013499:Surface Properties; D013817:Thermography; D014867:Water / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D010710:Phosphates; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D014867:Water; D012965:Sodium Chloride; D008012:Lidocaine; D012973:Sodium Hypochlorite; D002122:Calcium Chloride; D002126:Calcium Hydroxide; C031293:calcium silicate
keywords: Calcium hydroxide; differential scanning calorimetry; mineral trioxide aggregate; setting reaction; setting time