Incorporation of Recaldent into glass ionomer cement luting agents

Objectives:

The aim of this study is to investigate the concentration of Recaldent™ required to reduce the compressive strength of 3 commercially available glass ionomer luting cements (GIC) to an extent that it may function as temporary luting agents.

Materials & Methods:

Recaldent™ powder was manually incorporated into two conventional glass ionomer cements Ketac™ Cem Easy Mix® [KC] (3M ESPE AG Dental Products, D-82229 Seefeld, Germany) and GC Fuji I® [FI] plus a resin modified GIC, GC Fuji Plus® [FP](GC Int. Corp., Japan) on a w/w % ratio. Powder and liquid ratios of the glass ionomer cements were weighed based on manufacturer's recommendations. Increasing concentrations of Recaldent™ were utilised until the mean compressive strength was below 35 MPa. The other physical properties investigated were setting time and film thickness. Testing methods of ISO 9917:2003 were utilised. Five tests were carried out for each test group. Statistical analysis was carried out using Minitab® 14.1 software programme.

Results:

Increasing concentrations of Recaldent™ tended to reduce the compressive strength of all three glass ionomer cements. To obtain mean compressive strength values below 35 MPa, the incorporation of >20.0 w/w % Recaldent™ was required for KC (31.3±6.4 MPa), ³16.0 w/w % for FI (30.4±4.3 MPa) and ³14.0 w/w % for FP (30.0±4.4 MPa). Setting time was delayed beyond the ISO requirement of 8 minutes at ³12.0 w/w % Recaldent™ for both KC and FI and ³8.0 w/w % for FP. Film thickness was below 25 µm for ≤1.0 % for KC, ≤12.0% for FI and ≤8.0 % for FP.

Conclusions:

Mean compressive strengths of the three glass ionomer luting cements can be reduced to below 35 MPa by the incorporation of Recaldent™. The setting time and film thickness at these concentrations however does not comply with ISO requirements.