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

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 () or RM-GIC () 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, and , n = 6 of each. In the group, a resin coating agent () 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 group (). Flexural strengths of and 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 (). Flexural strengths of GICs were significantly higher than GICs ().

CONCLUSION

Resin coating increased flexural strengths of GICs under dry condition. HPL-GIC had higher porosities and lower flexural strength than RM- GIC.