Hydrolytic stability of experimental hydroxyapatite-filled dental composite materials.
OBJECTIVE
The purpose of this study was to analyze the behavior in water, related to mechanical properties, of experimental composites for dental restoration.


METHODS
The studied materials were composed of a visible-light-curing monomer mixture (Bis-GMA and TEGDMA or HEMA) and micrometric, nanometric or a mixture of both sizes hydroxyapatite particles as a reinforcing filler. Filler particles were modified with a coupling agent (citric, hydrosuccinic, acrylic or methacrylic acid or silane). The hydrolytic stability of the evaluated materials was studied through total elution and water-uptake tests. Percent net-mass variation was daily monitored and analyzed as a function of time. Mechanical performance was examined through flexural properties and Vickers hardness. Morphological surface changes were observed with scanning electron microscopy. ANOVA statistical analysis was performed (P<0.05).


RESULTS
In general, the use of HEMA instead of TEGDMA did not substantially worsen the composite quality. Dental composites containing only nanometric particles of hydroxyapatite as a filler are unsuitable for clinical performance. Midway-filled composite resins loaded with micro-HAP particles, coated with citric, acrylic or methacrylic acid displayed low percent elution and water-uptake values. Mechanical properties were similar or even superior to those measured for silane treated particles.


CONCLUSIONS
More research is needed to further improve the interaction of nano-HAP particles with the polymeric matrix, either as a single filler or, preferentially, mixed with micro-HAP, that will allow to increase the total loading of reinforcing filler and, hence, to improve the mechanical properties.
Domingo
C
C
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain. conchi@icmab.es
Arcís
R W
RW
Osorio
E
E
Osorio
R
R
Fanovich
M A
MA
Rodríguez-Clemente
R
R
Toledano
M
M
D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis; D017886:Durapatite; D004548:Elasticity; D006244:Hardness; D006860:Hydrogen Bonding; D006868:Hydrolysis; D008422:Materials Testing; D008689:Methacrylates; D010316:Particle Size; D018583:Pliability; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids; D012995:Solubility; D013499:Surface Properties; D014867:Water
D003188:Composite Resins; D008689:Methacrylates; D011109:Polymethacrylic Acids; D014867:Water; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; C005044:hydroxyethyl methacrylate; D017886:Durapatite