title: Fracture surface examination of dental ceramics using fractal analysis.
abstract: OBJECTIVE
  The purpose of this study was to measure the fractal dimensional increment of the fracture surface of six dental ceramics, and to measure the correlation of the fractal dimensional increment with fracture toughness. The six dental ceramics investigated were: a traditional porcelain (Finesse[F], Ceramco, Burlington, NJ, USA), four leucite reinforced pressable ceramics (Finesse Pressable [FP], Ceramco; Empress [E], Ivoclar; New Albany, NY, USA and two shades of OPC [OA2 and OI40], Jeneric-Pentron, MA, USA), and a lithium disilicate containing pressable ceramic ([LD] Ceramco).
  
  
  METHODS
  The fracture surfaces examined and the measured fracture toughness (K(IC)) values are from a previous study . An impression was taken of the fracture surface, poured up in epoxy, coated with gold, a second layer of epoxy added, and then the surface polished at an angle to the fracture surface. This fracture interface (slit island) was observed in an optical microscope with an imaging system from which an image of the fracture line was digitized. The slit island perimeter was then measured using five different length rulers. The fractal dimensional increment (D*) was determined using a Richardson technique. A second experiment on three ceramics investigated whether there was a correlation between fracture toughness and the values of D* measured by an alternative technique using a confocal microscope.
  
  
  CONCLUSIONS
  Fracture toughness was well correlated with D* using either technique.
authors.affiliation: Department of Restorative Dentistry m/c 555, 337A College of Dentistry, University of Illinois at Chicago, 801 South Paulina Street, Chicago, IL 60612-7212, USA. drummond@uic.edu
authors.forename: James L
authors.initials: JL
authors.lastname: Drummond
authors.forename: Michael
authors.initials: M
authors.lastname: Thompson
authors.forename: Boaz J
authors.initials: BJ
authors.lastname: Super
mesh_terms: D017607:Aluminum Compounds; D000538:Aluminum Silicates; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000379:methods*; D017709:Fractals; D006244:Hardness; D018020:Lithium Compounds; D008422:Materials Testing; D017640:Silicates; D013499:Surface Properties
chemical_list: D017607:Aluminum Compounds; D000538:Aluminum Silicates; C075815:IPS-Empress ceramic; D018020:Lithium Compounds; C105911:Optimal Pressed Ceramic; D017640:Silicates; D003776:Dental Porcelain; C047562:aluminum lithium silicate; C078519:leucite; C037884:finesse