Long-Term Compressive and Diametral Tensile Strength of RMGI Liner Materials

Objectives:   Evaluate the long-term compressive strength (CS) and diametral tensile strength (DTS) of a new resin modified glass ionomer liner.  The liners tested were 3M™ ESPE™ Vitrebond™ Plus Liner/Base (VBP) and 3M™ ESPE™ Vitrebond™ Liner/Base (VB). VBP is a  new resin-modified glass ionomer material in a paste/paste delivery, which exhibits the aluminum-carboxylate crosslinking reaction and fluoride release of a true glass ionomer.

Methods:   Samples were cured in 4mm diameter glass tubes with the paste held under axial compression, then cut to 8mm for compressive strength (CS) and 2 mm for diametral tensile strength (DTS).  Storage times in de-ionized water at 37°C were 1d, 1mo, and 3mo (n=5 for each group).  Samples were tested on an Instron machine at a crosshead speed of 0.5 mm/min.  The data were analyzed via one-way ANOVA and compared with Tukey's T-test (p<0.05).  

Results:  CS and DTS in MPa are shown below.

 

Liner	Time	CS,  MPa(stdev)	DTS, MPa(stdev)
VBP	1d	124.8 (4.7)	25.1(1.8)
VBP	1 mo	147.3(12.7)	29.6(2.4)
VBP	3 mo	149.8(7.6)	29.5(1.2)
VB	1d	85.9(18.5)	19.2(2.0
VB	1 mo	100.6(11.8)	19.8(2.8)
VB	3 mo	98.0(13.3)	22.2(1.4)

Conclusions:    The 1d, 1mo, and  3mo CS were statistically equivalent within each material group; the 1d, 1mo, and  3mo DTS were statistically equivalent within each material group.  CS and DTS of VBP were statistically higher than VB 1d, 1mo, and  3mo.   Both VB and VBP maintain their physical properties over the times tested.