Dental resin composites containing ceramic whiskers and precured glass ionomer particles

• Published in: Dental materials Vol. 16; no. 5; pp. 356 - 363
• Main Authors: Xu, H.H.K, Eichmiller, F.C, Antonucci, J.M, Schumacher, G.E, Ives, L.K
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-09-2000
• Subjects: Acrylic Resins; Analysis of Variance; Ceramic whisker; Ceramics; Compomers; Composite Resins - chemistry; Dental Polishing; Dental Restoration, Permanent; Dentistry; Elasticity; Fluoride; Fluorides - chemistry; Glass ionomer; Glass Ionomer Cements; Ion-Selective Electrodes; Magnesium Oxide; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Molar; Pliability; Polycarboxylate Cement; Reinforcement; Resin composite; Silanes; Silicates; Silicon Compounds; Silicon Dioxide; Statistics, Nonparametric; Strength; Stress, Mechanical; Surface Properties; Tensile Strength; Zinc Oxide; Reinforcement; Resin composite; Glass ionomer; Fluoride; Ceramic whisker; Strength
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/S0109-5641(00)00028-2

Objectives: Glass ionomer, resin-modified glass ionomer, and compomer materials are susceptible to brittle fracture and are inadequate for use in large stress-bearing posterior restorations. The aim of this study was to use ceramic single crystal whiskers to reinforce composites formulated with precured glass ionomer, and to examine the effects of whisker-to-precured glass ionomer mass ratio on mechanical properties, fluoride release, and polishability of the composites.
Methods: Silica particles were fused onto silicon nitride whiskers to facilitate silanization and to improve whisker retention in the matrix. Hardened glass ionomer was ground into a fine powder, mixed with whiskers, and used as fillers for a dental resin. Four control materials were also tested: a glass ionomer, a resin-modified glass ionomer, a compomer, and a hybrid composite. A three-point flexural test was used to measure flexural strength, modulus, and work-of-fracture. A fluoride ion-selective electrode was used to measure fluoride release. Composite surfaces polished simulating clinical procedures were examined by SEM and profilometry.
Results: At whisker/(whisker+precured glass ionomer) mass fractions of 1.0 and 0.91, the whisker composite had a flexural strength in MPa
(
mean (
SD);
n=6)
of (196 (10)) and (150 (16)), respectively, compared to (15 (7)) for glass ionomer, (39 (8)) for resin-modified glass ionomer, (89 (18)) for compomer, and (120 (16)) for hybrid composite. The whisker composite had a cumulative fluoride release of nearly 20% of that of the glass ionomer after 90 days. The whisker composites had surface roughness comparable to the hybrid resin composite.
Significance: Composites filled with precured glass ionomer particles and whiskers exhibit moderate fluoride release with improved mechanical properties; the whisker-to-glass ionomer ratio is a key microstructural parameter that controls fluoride release and mechanical properties.