Flexural strengths and porosities of coated or uncoated, high powder-liquid and resin-modified glass ionomer cements

Abstract

Background/purpose No study has previously investigated and compared whether resin coating could prevent the effect of dehydration on flexural strengths and porosities of high powder-liquid and resin-modified glass ionomer cements (HPL-GIC and RM-GIC). The purpose of this study is to investigate the effect of resin coating on flexural strengths and porosities of HPL-GIC and RM-GIC under a dry condition. Materials and methods HPL-GIC ( Equia Forte Fil ) or RM-GIC ( Fuji II LC ) was mixed and loaded into a mold to create a bar-shaped specimen, n = 12 of each. The specimens were randomly divided into two groups, coated and uncoated , n = 6 of each. In the coated group, a resin coating agent ( Equia Forte Coat ) was applied and light cured for 20 s. After 72 h, each specimen was dried and scanned to detect porosities (% volume) using micro-computed tomography. After scanning, flexural strength (MPa) of the specimen was tested using a three-point bending method. Results Porosities of HPL-GIC were significantly higher than RM-GIC, either coated or uncoated group ( p < .05 ). Flexural strengths of coated and uncoated HPL-GIC were 41.47 ± 0.89 and 15.32 ± 1.15 MPa that were significantly lower than those of RM-GIC at 104.77 ± 3.97 and 52.90 ± 2.17 MPa ( p < .05 ). Flexural strengths of coated GICs were significantly higher than uncoated GICs ( p < .05 ). Conclusion Resin coating increased flexural strengths of GICs under dry condition. HPL-GIC had higher porosities and lower flexural strength than RM- GIC.

Effect of enamel-surface modifications on shear bond strength using different adhesive materials

“…Moreover, GIC can release fluoride into the oral cavity and prevent caries. GIC has a specific adhesion to tooth tissues, but it has a lower bond strength with a higher falling rate after fixing orthodontic brackets [ 3 , 4 ].To increase the bond strength with the caries-resistance function of orthodontic brackets, the bonding agent denoted as resin-modified (RMGIC) appeared at the end of the twentieth century [ 5 ].…”

Effects of Protective Surface Coating on Fluoride Release and Recharge of Recent Uncoated High-Viscosity Glass Ionomer Cement

“…In addition, GICs present good biocompatibility [ 2 ], excellent coefficients of linear thermal expansion/contraction [ 2 , 4 , 5 ], and an excellent modulus of elasticity. However, a major disadvantage of GICs is their weak mechanical properties, such as low wear resistance, low fracture toughness [ 5 , 6 , 7 ], and sensitivity to moisture during the early stages of setting [ 4 , 7 , 8 , 9 , 10 , 11 , 12 ]. To overcome the limitations of conventional GICs, various modifications have been developed.…”

“…To overcome the limitations of conventional GICs, various modifications have been developed. By increasing the powder/liquid ratio and incorporating more reactive silicate particles [ 9 , 13 , 14 ], high-viscosity glass ionomer cements (HVGICs) were developed in 1990 [ 15 ].…”

“…HVGICs have improved mechanical properties [ 9 , 16 ] and faster setting reactions compared to GICs [ 6 , 13 , 14 , 16 ]. However, HVGICs are still sensitive to water absorption and dehydration during early setting reactions [ 4 , 8 , 11 , 17 ].…”

“…In addition, GICs present chemical bonding to the tooth structure, good biocompatibility, an excellent modulus of elasticity, and excellent coefficients of linear thermal expansion and contraction [ 2 , 29 ]. However, the long setting time [ 16 ], weak mechanical properties, and sensitivity to water sorption or dehydration in their initial setting reaction [ 9 ] are the main disadvantages of GICs. By increasing the powder/liquid ratio and incorporating more reactive silicate particles [ 14 ], high-viscosity GICs (HVGICs) were developed for better mechanical properties [ 9 ].…”