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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

CAD designed tooth/veneered zirconia crown system components. A: veneer porcelain, B: core, C: cement layers and D: tooth preparation.
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Figure 2: CAD designed tooth/veneered zirconia crown system components. A: veneer porcelain, B: core, C: cement layers and D: tooth preparation.

Mentions: The crown was realized by digitizing the prepared and unprepared mandibular right first molar resin model with an optical scanner (Optical 3D Scanner Activity 101, smart optics Sensortechnik GmbH, Bochum, Germany). The core and veneer porcelain were then designed using unprepared tooth resin model for the external shape of crown by CAD (FreeForm modeling systems, Sensable-Geomagic, MA, USA) (Fig. 1), and STL files were exported. The shoulder (1 mm in width) variations in core used in this study were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively and are listed in Table 1. In this process, ten different models were realized according to core designs. The solid models of a veneer layer (1 mm thick veneer porcelain), a core layer (0.5 mm thick zirconia), a cement layer (100 µm thick resin cement), and a tooth preparation (dentin) were then generated imitating the scanned images by CAD software (HyperWorks 10.0, Altair Engineering, Ontario, Canada) (Fig. 2). The veneered zirconia crown, the cement layer and the abutment tooth were assembled in the final model.


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)

CAD designed tooth/veneered zirconia crown system components. A: veneer porcelain, B: core, C: cement layers and D: tooth preparation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: CAD designed tooth/veneered zirconia crown system components. A: veneer porcelain, B: core, C: cement layers and D: tooth preparation.
Mentions: The crown was realized by digitizing the prepared and unprepared mandibular right first molar resin model with an optical scanner (Optical 3D Scanner Activity 101, smart optics Sensortechnik GmbH, Bochum, Germany). The core and veneer porcelain were then designed using unprepared tooth resin model for the external shape of crown by CAD (FreeForm modeling systems, Sensable-Geomagic, MA, USA) (Fig. 1), and STL files were exported. The shoulder (1 mm in width) variations in core used in this study were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively and are listed in Table 1. In this process, ten different models were realized according to core designs. The solid models of a veneer layer (1 mm thick veneer porcelain), a core layer (0.5 mm thick zirconia), a cement layer (100 µm thick resin cement), and a tooth preparation (dentin) were then generated imitating the scanned images by CAD software (HyperWorks 10.0, Altair Engineering, Ontario, Canada) (Fig. 2). The veneered zirconia crown, the cement layer and the abutment tooth were assembled in the final model.

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