Mechanical Properties of Visible-Light-Cured Resins Reinforced with Hydroxyapatite for Dental Restoration

W. ARCÍS, A. LÓPEZ-MACIPE, M.TOLEDANO, E. OSORIO, R.RODRÍGUEZ-CLEMENTE, M. A. FANOVICH AND C. DOMINGO

DENTAL MATERIALS

Elsevier

Año: 2002 p. 49 - 57

0109-5641

Objetives: The purpose of this study was to measure and analyze the mechanical properties af several composite materials designed for dental restoration. Methods: The materials were composed of a visible light-curing monomer mixture (either Bis-GMA + TEGDMA or Bis-GMA + HEMA) as a matrix and hydroxyapatite (either microscopic or nanoscopic particles) as a reinforcing filler. The surface of the hydroxyapatite particles was modified by using a coupling agent (citric, malic, acrylic or methacrylic acid). Five specimens of 14 different composites were prepared for each mechanical test: flexural strength, Young´s modulus and Vickers hardness. Mean values and standard deviations were calculated, and ANOVA and Student Neuman Keulsmultiple comparison tests were applied (P<0.05). Results: The addition of 50-60 wt% of hydroxyapatite particles to the unfilled mixtures led to the increase of both Young´s modulud and surface hardness of the materials, while the flexural strength decreased. In general, when microspopic instead of nanoscopic hydroxyapatite was used as a reinforcing filler, mechanical properties were favored. The mechanical properties were also improved by adding citric, acrylic or methacrylic acid as a coupling agent. Conclusions: An adequate surface modification of the hydroxyapatite particles conferred enhanced mechanical properties to the final dental composite. Microscopic-hydroxyapatite particles are preferred to nanoscopic ones.