IADR Abstract Archives
Impact strength, fracture toughness and brittleness of nine denture acrylics
Objective: The toughness of denture base polymers has a significant influence on the durability of removable dentures. Therefore, toughness tests as well as strength measurements were conducted on 9 denture acrylics (PMMA) with the objective to compare the brittleness of these materials and systems.
Methods: Four different acrylic systems designated as HI materials: Ivocap High Impact, ProBase High Impact (Ivoclar Vivadent), Lucitone 199 in the injection and packing technique (Dentsply), three non HI autopolymerising acrylics for injection technique: PalaXpress (Heraeus-Kulzer), FuturaGen (Schütz Dental), an experimental material (Ivoclar Vivadent), and two conventional materials (ProBase Cold (Ivoclar Vivadent) and Selecta Plus H (Dentsply)) were tested. The Charpy impact strength (CHP) was measured according to ISO 1567:2000, the fracture toughness (Kmax and FW) according to the single-edge notched bending test (SENB) and the universal hardness (UHN) according to ISO 14577. In addition, the brittleness index (BI) was calculated using the formula BI=UHN/Kmax. The data were analyzed using one-way ANOVA with post-hoc Scheffe's test (p≤0.05).
Results:
(Average±standard deviation)
|
Material |
Methode |
CHP |
Kmax |
FW |
UHN |
BI |
|
|
kJ/m² |
MPam½ |
J/m² |
MPa |
m-½ |
|
|
Ivocap High Impact |
Injection Hot |
2.6±0.4 |
2.14±0.16 |
1160±200 |
97±7 |
45 |
|
Exp. Mat. |
Injection Cold |
1.1±0.3 |
1.45±0.09 |
290±15 |
102±3 |
70 |
|
PalaXpress |
Injection Cold |
1.1±0.3 |
1.09±0.06 |
190±10 |
123±10 |
113 |
|
FuturaGen |
Injection Cold |
1.0±0.1 |
1.38±0.05 |
305±10 |
121±3 |
88 |
|
Lucitone 199 |
Injection Hot |
2.9±0.2 |
2.07±0.07 |
1280±40 |
109±4 |
52 |
|
Lucitone 199 |
Packing Hot |
3.0±0.2 |
2.25±0.05 |
1340±30 |
111±6 |
49 |
|
ProBase High Impact |
Packing Hot |
3.0±0.5 |
2.35±0.04 |
1500±30 |
108±4 |
55 |
|
ProBase Cold |
Pouring Cold |
1.1±0.3 |
1.46±0.07 |
440±20 |
100±2 |
69 |
|
SelectaPlus H |
Packing Hot |
1.3±0.2 |
1.26±0.07 |
300±30 |
119±6 |
95 |
Conclusion: Impact resistant and non-impact resistant denture base materials can be clearly distinguished by CHP, K(max), FW and brittleness index. All HI materials also showed a lower BI, indicating a higher resistance to brittle fracture.