title: The effect of three commonly used endodontic materials on the strength and hardness of root dentin.
abstract: The purpose of this study was to determine if calcium hydroxide, mineral trioxide aggregate, or sodium hypochlorite caused a change in the force required to fracture root dentin. Ten bovine central and lateral incisors were machined using various saws and drills to produce a cylinder of dentin with a 6.0-mm outer diameter 3.5-mm inner diameter and a length of 10 mm. The cylinders were cut lengthwise into four symmetrical pieces. The canal sides of the sections were then placed into Petri dishes containing a 1-mm depth of calcium hydroxide, mineral trioxide aggregate, sodium hypochlorite, or physiologic saline (control). The samples remained in the dishes for 5 weeks and were then shear tested by using an Instron machine. Data were analyzed using an ANOVA test for comparison of the groups as a whole, and a t test was used to compare each quarter section with its control from the same tooth. A 32% mean decrease in strength was discovered for calcium hydroxide, a 33% decrease in strength for mineral trioxide aggregate, and a 59% decrease for sodium hypochlorite. All decreases in strength were statistically significant: p < 0.001 for calcium hydroxide, p = 0.027 for mineral trioxide aggregate, and p < 0.001 for sodium hypochlorite. Results indicated that root dentin was weakened after 5 weeks of exposure to calcium hydroxide, mineral trioxide aggregate, or sodium hypochlorite.
authors.affiliation: Department of Restorative Dentistry, University of Alabama at Birmingham, 35294-0007, USA.
authors.forename: J Derek
authors.initials: JD
authors.lastname: White
authors.forename: William R
authors.initials: WR
authors.lastname: Lacefield
authors.forename: L S
authors.initials: LS
authors.lastname: Chavers
authors.forename: Paul D
authors.initials: PD
authors.lastname: Eleazer
mesh_terms: D017607:Aluminum Compounds / Q000009:adverse effects*; D000704:Analysis of Variance; D000818:Animals; D017610:Calcium Compounds / Q000009:adverse effects*; D002126:Calcium Hydroxide / Q000009:adverse effects*; D002417:Cattle; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects*; D004338:Drug Combinations; D006244:Hardness / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D010087:Oxides / Q000009:adverse effects*; D012387:Root Canal Filling Materials / Q000009:adverse effects*; D012388:Root Canal Irrigants / Q000009:adverse effects*; D033081:Shear Strength; D017640:Silicates / Q000009:adverse effects*; D012973:Sodium Hypochlorite / Q000009:adverse effects*; D013718:Tensile Strength / Q000187:drug effects; D014082:Tooth Fractures / Q000209:etiology; D014092:Tooth Root / Q000187:drug effects*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D017640:Silicates; C086631:mineral trioxide aggregate; D012973:Sodium Hypochlorite; D002126:Calcium Hydroxide