**3. Results**

In most assessed dentures was observed that the faults occurs mainly in the area where the thickness of denture is high, as indicated in figure 1. It was also noticed that, in the Eclipse dentures the density of defects may be higher than in the Meliodent dentures, but the defects in Eclipse may be smaller in size than those in Meliodent. This is due to different technologies for developing materials (heat curing polymerization – Meliodent and light curing polymerization – Eclipse).

The mechanical properties resulted after the experimental programs were given in table 2. The results show that, Eclipse Base Plate has a better elasticity compared to Meliodent and also a better fracture strength.


Table 2. Mechanical properties of the materials used for FEM analysis

For finite element analysis were considered four analysis models, each of them having a defect located in different areas of the denture. For all these cases have been evaluated the stress and strain states (fig. 16 - 24).

Since the materials have a brittle fracture behavior it was considered for this analysis the fracture criterion which takes into account the Maximum Principal Stress.

In all analyzed models, the presence of the faults has increased the stress and strain state, compared to the situation they are not considered. Moreover, this defects increased the fracture risk of denture. Thus, in case of model I the fracture risk of denture has increased by almoust 29 % due to present defect, in the second model the fracture risk increased by almost 14 %, in the third case was an increase of almost 90 % and in the latter case (the fourth model) the fracture risk increased with 18 %. The increased rates of fracture risk of denture were determined reporting the actual stress states to the stress state of the same

Fig. 16. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the first analysis model for denture with Eclipse material

272 Reverse Engineering – Recent Advances and Applications

In most assessed dentures was observed that the faults occurs mainly in the area where the thickness of denture is high, as indicated in figure 1. It was also noticed that, in the Eclipse dentures the density of defects may be higher than in the Meliodent dentures, but the defects in Eclipse may be smaller in size than those in Meliodent. This is due to different technologies for developing materials (heat curing polymerization – Meliodent and light

The mechanical properties resulted after the experimental programs were given in table 2. The results show that, Eclipse Base Plate has a better elasticity compared to Meliodent and

> Tensile Young's modulus, E [MPa]

Eclipse 80.16 3390 4.06 127 Meliodent 68.62 1215 8.76 118

For finite element analysis were considered four analysis models, each of them having a defect located in different areas of the denture. For all these cases have been evaluated the

Since the materials have a brittle fracture behavior it was considered for this analysis the

In all analyzed models, the presence of the faults has increased the stress and strain state, compared to the situation they are not considered. Moreover, this defects increased the fracture risk of denture. Thus, in case of model I the fracture risk of denture has increased by almoust 29 % due to present defect, in the second model the fracture risk increased by almost 14 %, in the third case was an increase of almost 90 % and in the latter case (the fourth model) the fracture risk increased with 18 %. The increased rates of fracture risk of denture were determined reporting the actual stress states to the stress state of the same

a) b)

Fig. 16. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the first

Total Elongation At [%]

Flexural Strength σf [MPa]

**3. Results** 

curing polymerization – Eclipse).

also a better fracture strength.

stress and strain states (fig. 16 - 24).

analysis model for denture with Eclipse material

Ultimate Tensile Strength σuts [MPa]

Table 2. Mechanical properties of the materials used for FEM analysis

fracture criterion which takes into account the Maximum Principal Stress.

Material

Fig. 18. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the first analysis model for denture with Meliodent material

Fig. 19. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the second analysis model for denture with Eclipse material

Reverse Engineering and FEM Analysis

fourth analysis model for denture with Eclipse material

denture with Eclipse material

stress state and fracture strain.

**4. Conclusions** 

for Mechanical Strength Evaluation of Complete Dentures: A Case Study 275

a) b) Fig. 23. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the

Fig. 24. The Maximum Principal Stress around the defect in the fourth analysis model for

defects and because of this it not influence too much the stress and strain state.

optimization, especially in objects with complex geometry.

denture, loaded in the same way but without defects. These results indicate a greater influence on the stress state when the defect is closer to the bottom of the denture and less if the defect is almost to the upper surface of the denture. Defect in the fourth model, although it has a large surface area, is at the limit of the area indicated as the highest density of

In the case of Meliodent denture was observed the same influence of presence defects on

The methodology presented in this paper consist in 3D scanning of a real object, processing of the scanned results by reverse engineering and obtaining a digital geometric model and conducting numerical analysis. This methodology can by successfully applied in design

Fig. 21. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the third analysis model for denture with Eclipse material

Fig. 22. The Maximum Principal Stress around the defect in the third analysis model for denture with Eclipse material

274 Reverse Engineering – Recent Advances and Applications

Fig. 20. The Maximum Principal Stress around the defect in the second analysis model for

a) b)

Fig. 21. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the

Fig. 22. The Maximum Principal Stress around the defect in the third analysis model for

third analysis model for denture with Eclipse material

denture with Eclipse material

denture with Eclipse material

Fig. 23. The Maximum Principal Stress (a) and Maximum Principal Strain (b) state in the fourth analysis model for denture with Eclipse material

Fig. 24. The Maximum Principal Stress around the defect in the fourth analysis model for denture with Eclipse material

denture, loaded in the same way but without defects. These results indicate a greater influence on the stress state when the defect is closer to the bottom of the denture and less if the defect is almost to the upper surface of the denture. Defect in the fourth model, although it has a large surface area, is at the limit of the area indicated as the highest density of defects and because of this it not influence too much the stress and strain state.

In the case of Meliodent denture was observed the same influence of presence defects on stress state and fracture strain.
