Properties of glass ionomer cements incorporating nano-sized particles were affected by factors such as the materials, particle size, synthetic methods, contents, and types of cements. Incorporated nanoparticles were reported to be metals, oxides such as TiO₂, inorganic materials, linear polymers, calcium phosphates, and nanoparticles with pharmaceutical agents expected to have pharmacological effects. Previous studies indicated that the mechanical properties, amount of fluoride release, and antibacterial properties of glass ionomer cements could be improved by incorporating the optimum composition of nanoparticles. The improvement in mechanical properties of glass ionomer cements was explained by forming a strong cement matrix structure with nanoparticles and/or creating a cement matrix with a higher density by homogenous dispersion of nanoparticles. Changes in cement properties by the incorporation of nanoparticles over a prolorged period are unknown, and there is a lack of clinical reports on the effects of nanoparticle incorporation into cement. It is expected that the incorporation of nanoparticles not only improves mechanical properties but also promotes higher level functions, such as distinct anticaries properties and the remineralization of tooth structures.

The study examined the effect of specimen thickness on the shear punch strength of dental luting cements. One conventional glass ionomer cement (CGIC), two resin-modified glass ionomer cements (RMGIC), and three self-adhesive resin cements (SARC) were used in this study. Disk specimens with five different thicknesses (0.15～2.00 mm) were prepared for each cement. The shear strengths were determined using a punch tool (n＝10 for each condition). Two-dimensional finite element analysis (FEA) was employed to examine the shear stress distribution in each specimen. Shear strength values of RMGIC and SARC tended to rise with an increase in the specimen thickness, while those of CGIC were independent of the specimen thickness. FEA indicated that the shear stress distribution in specimens for the punch-shear test was affected by the specimen thickness. The specimen thickness was suggested to affect the measured shear punch strength values for the dental luting cements containing resin components.