Figure 6. Figure 6. a–d Von Mises stress distribution on bone. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. The stress concentration occurred in the cortical bone around the neck of the implant. Groups L-M and ZL-M were quite similar and reduced stress
Figure 5. a–d Von Mises stress distribution on abutment. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. Von Mises stresses were relatively similar and concentrated at the coronal part of the abutment in all groups
Figure 5. a–d Von Mises stress distribution on abutment. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. Von Mises stresses were relatively similar and concentrated ...
Figure 4. a–d Von Mises stress distribution on implant. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 4. a–d Von Mises stress distribution on implant. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 3. a–d Maximum principal stress distribution on crown restoration. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 3. a–d Maximum principal stress distribution on crown restoration. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 2. The graph of the interaction of the materials and restoration design
Group
N
Mean (N)
Standard deviation
Minimum
Maximum
L-M
12
2891.88a
410.12
2079.74
3486.96
L-V
12
2077.37bc
356.59
1220.96
2493.39
ZL-M
12
1750.28c
314.96
1084.36
2163.95
ZL-V
12
2202.55b
503.14
1292.20
2912.81
Material
Young’s modulus (GPa)
Poisson ratio
Reference
E.max CAD
95
0.20
[1]
Vita Suprinity
65
0.23
[2]
Vita VM 11
65
0.23
*
E.max Ceram
64
0.23
[4]
Implant and abutment
114
0.34
[5]
Cortical bone
13.7
0.3
[5]
Spongious bone
1
0.3
[5]
Figure 1. Crown restoration design
Groups
N
Materials
L-M
12
IPS e-max CADIPS e.max CAD glaze
L-V
12
IPS e-max CADe.max Ceram DentinIPS e.max Ceram Glaze
ZL-M
12
Vita SuprinityVita Akzent Plus
ZL-V
12
Vita SuprinityVM-11Vita Akzent Plus
Material
Chemical composition (%)
Coefficient of thermal expansion (10−6 K−1)
Flexural strength (MPa)
Manufacturer
IPS e.max CAD; lithium disilicate glass ceramic (LDS)
SiO2 (57–80), Li2O (11–19), K2O (0–13), P2O5 (0–11), ZrO2 (0–8), ZnO (0–8), Al2O3 (0–5), MgO (0–5), coloring oxides (0–8)
10.2
360
Ivoclar Vivadent
IPS e.max Ceram; low-fusing nan...
Conclusions
Within the limitation of the present study, it can be concluded that the restoration design affected the failure load of ceramics. Monolithic design had a statistically significant effect on the failure load of two different ceramics (LDS > ZLS). Veneer application had opposite effects on two different ceramics which increased the failure load of ZLS and reduced it for LDS witho...
Zheng et al. compared the stress distribution of the same veneering ceramic on different cores and concluded that the zirconia core was clearly different from other materials with higher tensile stresses at the veneer core interface because the increasing differences between the elasticity modulus of the core and the veneer transmitted higher stress concentrations to the cores. Con...
Veneer application provided additional strength to the ZLS crowns in contrast to the LDS crowns. The higher failure load of the veneered ZLS crowns (2202.55 N; group L-V 2077.37 N) may be associated with the higher flexural strength of the veneering porcelain VM-11 (100 MPa; emax Ceram 90 MPa). These veneered groups had a statistically significant difference from the monoli...
Similar results were presented in a study of Traini et al. as it was concluded that ZLS was comparable to that of existing zirconia-based ceramics and was suitable for oral function even in the posterior regions. In the literature, there have been few studies on this ceramic and a limited number of them include the failure load of the material. In one of these studi...
In literature, it has been stated that the failure load of LDS crowns was higher than veneered zirconia and could be comparable with metal ceramic systems. Doğan et al. evaluated the fracture strength of different CAD/CAM-manufactured crowns and concluded that the monolithic LDS crowns had the highest fracture resistance. Present study confirmed as monolithic LDS crowns demonstrated so satisfying...
Discussion
Implant-supported restorations have been accepted as an alternative treatment for the rehabilitation of edentulous spaces. Despite the high success rates, implant failures are inevitable and classified as early or late implant failures. Late implant failures are observed after prosthetic restoration which is primarily related to biomechanical complications. Since occlusal loads are t...
Results
Descriptive analysis (mean, standard deviation (SD), minimum, maximum) of the groups is presented in Table 4.
Group L-M exhibited the highest failure load values (2891.88 N ± 410.12 N), and the lowest values were observed in group ZL-M (1750.28 N ± 314.96 N). Two-way ANOVA indicated a statistically significant difference between materials and veneering technique (p = 0.00 < ...
Statistical analysis
The statistical analysis was performed with SPSS 24.0 (SPSS Inc, Chicago, USA). The Kolmogorov–Smirnov normality test was used to evaluate whether the data distribution of the groups was normal. The homogeneity of the variances was analyzed by Levene’s test. Since test results indicated that data distribution of the groups was normal and the variances were homogenous,...
All crowns were subjected to a combination firing that included crystallization and glaze firing according to each manufacturer’s guidelines in the ceramic furnace (Vita Vacumat 6000 M, Vita Zahnfabrik, Bad Sackingen, Germany).
For veneered restorations, the design mode was changed to “split,” and the core was constructed in 0.6-mm thickness. In group L-V (n = 12), e.max ...
Methods
Preparation of test groups
This study tested the current glass ceramic ZLS by comparing LDS with monolithic and conventional veneering techniques in implant-supported crowns: group L-M: lithium disilicate ceramic (monolithic), group L-V: lithium disilicate ceramic (conventional veneering), group ZL-M: zirconia-reinforced lithium silicate ceramic (monolithic), group ZL-V: zirconia-reinf...
Background
Implants have been successfully used to replace missing teeth for many years. Notwithstanding the high success rates, complications such as screw loosening and/or fracture, prosthesis fracture, and even implant fracture are inevitable. The reasons of the complication may be related to decreased proprioception and low tactile sensitivity which makes implant-supported crowns more susc...
Abstract
Background
Present study compared the failure load of CAD/CAM-manufactured implant-supported crowns and the stress distribution on the prosthesis-implant-bone complex with different restoration techniques.
Methods
The materials were divided into four groups: group L-M: lithium disilicate ceramic (LDS, monolithic), group L-V: LDS ceramic (veneering), group ZL-M: zirconia-reinforced l...