Reliability of Glass Ceramic and CAD-CAM Composite Occlusal Veneers
Objectives: To evaluate the reliability and failure mode of reduced thickness occlusal overlays fabricated from either glass-ceramics or a CAD-CAM composite. Methods: An anatomic model of a mandible first molar was created with an occlusal reduction of 0.5 mm. Then, based on the designed tooth preparation, a 0.5-mm thickness occlusal overlay was modeled and milled using two different materials: (i) glass ceramic (e.max Press) (IPS e.max Press, Ivoclar Vivadent) and (ii) CAD/CAM Composite (Lava) (Lava Ultimate, 3M OralCare) (n=21/group). The specimens were cemented according to manufacturer’s instructions. First, overlays were subjected to single load to failure test for stress profile design (n=3/group): mild, moderate and aggressive resulting in a specimen ratio distribution of 3:2:1. Mouth-motion step-stress fatigue was performed under water by sliding an indenter 0.5mm lingually down the distobuccal cusp. Use level probability Weibull curves and reliability for missions of 100,000 cycles at 150, 200, 250 and 300N with 90% confidence intervals were calculated. Failed samples were analyzed in a polarized-light stereomicroscope and scanning electron microscope in order to classify failure patterns and identify failure origin and fractographic marks. Results: The beta (β) values were 1.26(0.67-2.38) and 1.32(0.56-3.07) for e.max Press and Lava, respectively, indicating that failure rates increased with fatigue. The calculated reliability showed that the cumulative damage from a load reaching 100N would keep the probability of survival higher than 90% for both materials. However, the higher the load requirement, the higher the probability of survival for Lava relative to e.max Press. For missions of 250 and 300N, Lava overlays outperformed e.max Press with more than 50% survivability. Failure chiefly comprised cohesive chips for both groups. Conclusions: CAD/CAM composite overlays presented higher probability of survival than glass-ceramics under high loads.
Division: IADR/PER General Session
Meeting:2018 IADR/PER General Session (London, England) Location: London, England
Year: 2018 Final Presentation ID:2493 Abstract Category|Abstract Category(s):Dental Materials 2:Polymer-based Materials
Authors
Hirata, Ronaldo
( New York University
, New York
, New York
, United States
)
Bergamo, Edmara
( UNICAMP
, Marialva
, Parana
, Brazil
; New York University
, New York
, New York
, United States
)
Bordin, Dimorvan
( University of Guarulhos
, Guarulhos
, Brazil
; New York University
, New York
, New York
, United States
)
Ramalho, Ilana
( University of São Paulo/Campus Bauru
, Bauru
, Brazil
; New York University
, New York
, New York
, United States
)
Romanini Junior, Jose Carlos
( Guarulhos University
, Guarulhos
, SP
, Brazil
)
Bonfante, Estevam
( University of São Paulo
, Bauru
, Brazil
)
Coelho, Paulo
( New York University
, New York
, New York
, United States
)
Calculated reliability (%) for a given mission of 100,000 cycles at different loads.
IPS E.max
IPS E.max
IPS E.max
LAVA
LAVA
LAVA
LOAD
Lower Bound
Reliability
Upper Bound
Lower Bound
Reliability
Upper Bound
100N
67
91 aA
97
88
99 aA
99
150N
45
73 aAB
88
77
95 aAB
99
200N
26
48 aBC
66
63
87 aABC
95
250N
11
24 aCD
39
49
72 bBC
86
300N
2
8 aD
19
32
52 bC
68
BETA
0.67
1.26
2.38
0.56
1.32
3.07
Different lowercase letters mean statistical difference between overlay material.
Different uppercase letters mean statistical difference between load levels.