Longterm adhesion to tooth structure and expansion are essential properties for the clinical success of resin-based luting materials.
Objectives:
The present study compares the behavior of linear expansion and tensile bond strength (TBS) on bovine dentin of commercially available resin-based luting materials (self-curing mode).
Methods:
TBS was determined according to the method described in J. Dent. Res. 76,1997,313 using 5 specimens of each material and conditioning or bonding procedures recommended by the manufacturer. For simulating longterm clinical situation specimens of RelyX Unicem were stored in Ringer’s solution at 36 °C. TBS was measured after 3m and 1y. To determine linear expansion specimens were prepared according to ISO 4049:2000 (7.11) and stored in deionized water at 36 °C to age the materials. The length of the specimens was measured initially, after 1w, 1m, 3m and 6m and linear dimensional changes were calculated. The results (±standard deviation) are summarized in the following table. Average values marked by the same characters do not significantly differ (multiple range test p<0.05).
| TBS [MPa] | Dyract Cem Plus | | Variolink II | Panavia F | RelyX Unicem |
| 1d | 0.9±1.6a | 1.6±1.6a,b | 1.0±0.5a | 3.3±1.5b,c | 2.7±0.9a,b,c |
| Lin. expansion [%] |
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| 1w | 0.45±0.06f | 1.72±0.07g | 0.15±0.02d | 0.20±0.00d | 0.31±0.07e |
| 1m | 0.55±0.12k | 1.93±0.06l | 0.23±0.02h | 0.25±0.02h | 0.42±0.08i |
| 3m | 0.59±0.12n | 1.90±0.06o | 0.23±0.02m | 0.33±0.02m,n | 0.44±0.08n |
| 6m | 0.65±0.10q | 1.91±0.02r | 0.24±0.04o | 0.44±0.00p | 0.48±0.07p |
Results:
The new universal cement RelyX Unicem shows comparable or higher results of adhesion than the other tested materials. Aging of RelyX Unicem leads with 4.5±1.9 (3m) and 4.0±2.7 (1y) to higher mean values, which statistically do not differ from the 1d-value.
For linear expansion the following ranking was found: Fuji Plus >> Dyract Cem Plus > Panavia F, RelyX Unicem > Variolink.
Conclusions:
The obtained data for RelyX Unicem support promising longterm behavior of this new universal cement.