Objective: To determine the relationship between surface microhardness, compression deformation, subsurface microhardness, and subsurface damage in nine resin composites.
Methods: Five disks (dia 7mmx2.5mm) of nine composites1-9 were fabricated using a PTFE mould. The disks were subjected to 2000 compression cycles (0-120 N) with a rounded cone indenter using a crosshead speed of 1mm sec-1. The diameter of the surface compression scar was measured and the surface microhardness determined with a Vickers indenter (Zeiss). The specimens were then immersed in AgNO3 for 3 days, sectioned, ground and polished. The area of silver-stained subsurface damage was measured using image analysis software (SigmaScan Pro 5.0). Three subsurface microhardness measurements were measured. Data were analysed for significant correlations (SPSS).
Results:
|
Material |
Surface Hard (K/mm2) |
Subsurface Hard (K/mm2) |
Surface Deformation (μm) |
Subsurface Damage (μm2x10-3) |
|
Admira |
58.1 ± 1.7 |
69.5 ± 6.5 |
852.0 ± 157.9 |
0.0 |
|
Clearfil |
96.8 ± 19.8 |
140.0 ± 23.7 |
564.0 ± 43.4 |
58.9 ± 43.9 |
|
Concise |
73.1 ± 6.2 |
454.0 ± 66.7 |
642.0 ± 200.4 |
224.6 ± 115.3 |
|
Durafill |
31.3 ± 11.2 |
51.1 ± 27.4 |
774.0 ± 45.1 |
0.0 |
|
Grandio |
82.8 ± 3.4 |
100.0 ± 33.7 |
614.0 ± 115.5 |
151.3 ± 30.3 |
|
Grandio-F |
55.0 ± 3.6 |
93.2 ± 14.9 |
722.0 ± 71.9 |
128.3 ± 61.6 |
|
Herculite |
67.9 ± 6.6 |
74. ± 82.9 |
552.0 ± 31.1 |
0.0 |
|
Occlusin |
67.6 ± 3.1 |
105.0 ± 10.2 |
662.0 ± 37.0 |
150.0 ± 20.2 |
|
Spectrum |
61.2 ± 0.2 |
96.7 ± 4.5 |
748.0 ± 98.8 |
15.4 ± 10.2 |
Significant correlations: Surface Hardness vs. Surface Deformation (r=-514, p<0.001). Subsurface Hardness vs. Subsurface damage (r=636, p<0.001).
Conclusion: For the resin composites tested the harder the surface hardness, the less the surface deformation; the harder the subsurface, the greater the subsurface damage.
1Admira (Voco) 2Clearfil (Cavex) 3Concise (3M-ESPE) 4Durafill (Kulzer) 5Grandio (Voco) 6Grandio-Flow (Voco) 7Herculite (Kerr) 8Occlusin (ICI) 9Spectrum (Dentsply).