Limits...
The influence of various core designs on stress distribution in the veneered zirconia crown: a finite element analysis study.

Ha SR, Kim SH, Han JS, Yoo SH, Jeong SC, Lee JB, Yeo IS - J Adv Prosthodont (2013)

Bottom Line: In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally.MPS increased in the shoulder region as the shoulder height increased.This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

View Article: PubMed Central - PubMed

Affiliation: Department of Dentistry, Ajou University School of Medicine, Suwon, Republic of Korea.

ABSTRACT

Purpose: The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns.

Materials and methods: Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a 45° angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position.

Results: In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased.

Conclusion: This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

No MeSH data available.


Related in: MedlinePlus

Lingual side view of minimum principal stress distributions of 10 models subjected to masticatory force (under the application of loads from three directions). (1) load of 28 0 N at 0° to the tooth axis (vertical direction), (2) load of 280 N at 45° to the tooth axis, towards the lingual margin, and (3) load of 280 N at 90° to the tooth axis, towards the lingual surface (horizontal direction). A: Model 1, B: Model 2, C: Model 3, D: Model 4, E: Model 5, F: Model 6, G: Model 7, H: Model 8, I: Model 9 and J: Model 10.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3675293&req=5

Figure 9: Lingual side view of minimum principal stress distributions of 10 models subjected to masticatory force (under the application of loads from three directions). (1) load of 28 0 N at 0° to the tooth axis (vertical direction), (2) load of 280 N at 45° to the tooth axis, towards the lingual margin, and (3) load of 280 N at 90° to the tooth axis, towards the lingual surface (horizontal direction). A: Model 1, B: Model 2, C: Model 3, D: Model 4, E: Model 5, F: Model 6, G: Model 7, H: Model 8, I: Model 9 and J: Model 10.

Mentions: Fig. 8 shows the lingual side view of minimum principal stress distributions within the ten models under maximum bite force. The minimum principal stress distributions within ten models subjected to masticatory force at three directions are presented in Fig. 9. Overall, the compressive stress levels within the ceramic core were located in 2 different regions as a function of shoulder height and position on the core. These locations were cusp region around loading points and shoulder region, as the all shoulder height increased up to 3 mm from the margin. Also, it was observed that the tensile stress areas around loading points on the surface of veneer decreased as the all shoulder height increased from 0 to 3 mm. Under maximum bite force simulations, the highest compressive stresses were located at the occlusal region around loading points on the veneer surface. Tensile stresses also concentrated in the areas around the loading points on the crown surface. However, no particular concentration of tensile stresses was observed on the shoulder region. Compressive stresses were high in the cervical shoulder region of the ceramic core. As the height of shoulder increased, compressive stresses increased in the shoulder region, and tensile stresses decreased around loading points. This phenomenon was dramatic in Model 10. No significant changes in stress area were observed at buccal cusp area, as the height of lingual shoulder increased without buccal shoulder. In the shoulder region, the stresses were high in the top of shoulder and gradually decreased from top to the margin. Under masticatory force simulations, the compressive stresses were located at the loading points and shoulder region. Angular loading resulted in a general increase of compressive stresses at the shoulder region as the height of the lingual shoulder increased up to 3 mm from 2 mm. The supportive effect of lingual shoulder was small in the models those had 1 mm height lingual shoulder, and those had 2 mm height lingual shoulder without buccal shoulder. Horizontal loading showed the supportive effect of lingual shoulder in the models those had 3 mm height lingual shoulder regardless of buccal shoulder.


The influence of various core designs on stress distribution in the veneered zirconia crown: a finite element analysis study.

Ha SR, Kim SH, Han JS, Yoo SH, Jeong SC, Lee JB, Yeo IS - J Adv Prosthodont (2013)

Lingual side view of minimum principal stress distributions of 10 models subjected to masticatory force (under the application of loads from three directions). (1) load of 28 0 N at 0° to the tooth axis (vertical direction), (2) load of 280 N at 45° to the tooth axis, towards the lingual margin, and (3) load of 280 N at 90° to the tooth axis, towards the lingual surface (horizontal direction). A: Model 1, B: Model 2, C: Model 3, D: Model 4, E: Model 5, F: Model 6, G: Model 7, H: Model 8, I: Model 9 and J: Model 10.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675293&req=5

Figure 9: Lingual side view of minimum principal stress distributions of 10 models subjected to masticatory force (under the application of loads from three directions). (1) load of 28 0 N at 0° to the tooth axis (vertical direction), (2) load of 280 N at 45° to the tooth axis, towards the lingual margin, and (3) load of 280 N at 90° to the tooth axis, towards the lingual surface (horizontal direction). A: Model 1, B: Model 2, C: Model 3, D: Model 4, E: Model 5, F: Model 6, G: Model 7, H: Model 8, I: Model 9 and J: Model 10.
Mentions: Fig. 8 shows the lingual side view of minimum principal stress distributions within the ten models under maximum bite force. The minimum principal stress distributions within ten models subjected to masticatory force at three directions are presented in Fig. 9. Overall, the compressive stress levels within the ceramic core were located in 2 different regions as a function of shoulder height and position on the core. These locations were cusp region around loading points and shoulder region, as the all shoulder height increased up to 3 mm from the margin. Also, it was observed that the tensile stress areas around loading points on the surface of veneer decreased as the all shoulder height increased from 0 to 3 mm. Under maximum bite force simulations, the highest compressive stresses were located at the occlusal region around loading points on the veneer surface. Tensile stresses also concentrated in the areas around the loading points on the crown surface. However, no particular concentration of tensile stresses was observed on the shoulder region. Compressive stresses were high in the cervical shoulder region of the ceramic core. As the height of shoulder increased, compressive stresses increased in the shoulder region, and tensile stresses decreased around loading points. This phenomenon was dramatic in Model 10. No significant changes in stress area were observed at buccal cusp area, as the height of lingual shoulder increased without buccal shoulder. In the shoulder region, the stresses were high in the top of shoulder and gradually decreased from top to the margin. Under masticatory force simulations, the compressive stresses were located at the loading points and shoulder region. Angular loading resulted in a general increase of compressive stresses at the shoulder region as the height of the lingual shoulder increased up to 3 mm from 2 mm. The supportive effect of lingual shoulder was small in the models those had 1 mm height lingual shoulder, and those had 2 mm height lingual shoulder without buccal shoulder. Horizontal loading showed the supportive effect of lingual shoulder in the models those had 3 mm height lingual shoulder regardless of buccal shoulder.

Bottom Line: In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally.MPS increased in the shoulder region as the shoulder height increased.This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

View Article: PubMed Central - PubMed

Affiliation: Department of Dentistry, Ajou University School of Medicine, Suwon, Republic of Korea.

ABSTRACT

Purpose: The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns.

Materials and methods: Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a 45° angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position.

Results: In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased.

Conclusion: This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

No MeSH data available.


Related in: MedlinePlus