title: Mechanical properties and wear behavior of light-cured packable composite resins.
abstract: OBJECTIVE
  Determination of flexural strength, flexural modulus, fracture toughness and wear resistance of three packable composites (Solitaire, Surefil, ALERT) and a packable ormocer (Definite) in comparison with an advanced hybrid composite (Tetric Ceram) and an ion-releasing composite (Ariston pHc).
  
  
  METHODS
  Flexural strength, flexural modulus and fracture toughness of each material were determined in three-point bending (each test n = 10). Single-edge notched-bend specimens were used to evaluate the fracture toughness (K1C). Wear of the materials (n = 8) was determined in a pin-on-block-design with a spherical Degusit antagonist at 50 N vertical load and quantified by a replica technique using a 3D-laser scanner. Replicas were made after 6000, 10,000, 30,000 and 50,000 load cycles. The mean wear rate (MWR (micron 3 cycle-1)) was obtained by a linear regression analysis in the steady-state of the time-wear-curve. All results were statistically analyzed with ANOVA and post hoc Tukey HSD tests (p < 0.05).
  
  
  RESULTS
  ALERT exhibited the highest flexural modulus (12.5 +/- 2.1 GPa) and K1C (2.3 +/- 0.2 MN m-3/2), but the lowest wear resistance (8275 micron 3 cycle-1). Solitaire presented the highest wear resistance (1591 micron 3 cycle-1), but significantly lower flexural strength (81.6 +/- 10.0 MPa), flexural modulus (4.4 +/- 0.3 GPa), and K1C (1.4 +/- 0.2 MN m-3/2) than all other materials. Surefil revealed a significantly higher flexural modulus (9.3 +/- 0.9 GPa) and wear resistance (3028 micron 3 cycle-1) than Tetric Ceram (6.8 +/- 0.5 GPa; 5417 micron 3 cycle-1) and Ariston pHc (7.3 +/- 0.8 GPa; 7194 micron 3 cycle-1).
  
  
  CONCLUSIONS
  The tested packable composite resins differed significantly in their mechanical properties. This study suggested that fracture and wear behavior of the composite resins are highly influenced by the filler system. Overall, Surefil demonstrated good fracture mechanics parameters and a low wear rate.
authors.affiliation: Department of Restorative Dentistry, Dental School of the LMU-University, Munich, Germany. manhart@manhart.com
authors.forename: J
authors.initials: J
authors.lastname: Manhart
authors.forename: K H
authors.initials: KH
authors.lastname: Kunzelmann
authors.forename: H Y
authors.initials: HY
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Hickel
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D019554:Dental Restoration Wear; D006244:Hardness; D008422:Materials Testing; D019563:Mechanics; D008689:Methacrylates / Q000737:chemistry; D010316:Particle Size; D018583:Pliability; D016062:Porosity; D012833:Siloxanes / Q000737:chemistry; D018709:Statistics, Nonparametric; D013729:Terpenes / Q000737:chemistry
chemical_list: C406265:Alert composite resin; C409382:Ariston pHc; D003188:Composite Resins; C421785:Definite composite resin; D008689:Methacrylates; D012833:Siloxanes; C113049:Solitaire composite resin; C403464:SureFil packable composite; D013729:Terpenes; C121818:Tetric ceram