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Dental prostheses mimic the natural enamel behavior under functional loading: A review article

View Article: PubMed Central - PubMed

ABSTRACT

Alumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores), and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ) structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability.

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Models of biocomposites. (a) Perfectly staggered mineral inclusions embedded in protein matrix. (b) A tension–shear chain model of biocomposites in which the tensile regions of protein are eliminated to emphasize the load transfer within the composite structure. (c) The free body diagram of a mineral crystal.
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fig0005: Models of biocomposites. (a) Perfectly staggered mineral inclusions embedded in protein matrix. (b) A tension–shear chain model of biocomposites in which the tensile regions of protein are eliminated to emphasize the load transfer within the composite structure. (c) The free body diagram of a mineral crystal.

Mentions: Although most of the enamel organic matrix is removed during mineralization and maturation, some protein, notably ameloblastin, is retained, primarily at the incisal edges and proximal sides of rod boundaries defining a rod sheath [75]. This prevents cracks from advancing straight through enamel to cause catastrophic macro-mechanical failure, but instead spreads the damage laterally and hence energy absorbed over a larger volume. Also, the presence of minute quantities of protein remnants could allow limited differential movement between adjacent rods. Limited slippage could reduce stresses without crack growth. The minor components of enamel, protein remnants and water, have a profound plasticizing effect. As mentioned previously, the protein matrix behaves like a soft wrap around the mineral platelets and protects them from the peak stresses caused by the external load and homogenizes stress distribution within the composite structure. At the most elementary structure level, natural biocomposites exhibit a generic microstructure consisting of staggered mineral bricks. It was proposed that under an applied tensile stress, the mineral platelets carry the tensile load while the protein matrix transfers the load between mineral crystals via shear [80]. The strength of the protein phase in a biological material is amplified by the large aspect ratio of mineral platelets. Besides, the larger volume concentration of protein significantly reduces impact damage to the protein–mineral interface (Fig. 1).


Dental prostheses mimic the natural enamel behavior under functional loading: A review article
Models of biocomposites. (a) Perfectly staggered mineral inclusions embedded in protein matrix. (b) A tension–shear chain model of biocomposites in which the tensile regions of protein are eliminated to emphasize the load transfer within the composite structure. (c) The free body diagram of a mineral crystal.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382785&req=5

fig0005: Models of biocomposites. (a) Perfectly staggered mineral inclusions embedded in protein matrix. (b) A tension–shear chain model of biocomposites in which the tensile regions of protein are eliminated to emphasize the load transfer within the composite structure. (c) The free body diagram of a mineral crystal.
Mentions: Although most of the enamel organic matrix is removed during mineralization and maturation, some protein, notably ameloblastin, is retained, primarily at the incisal edges and proximal sides of rod boundaries defining a rod sheath [75]. This prevents cracks from advancing straight through enamel to cause catastrophic macro-mechanical failure, but instead spreads the damage laterally and hence energy absorbed over a larger volume. Also, the presence of minute quantities of protein remnants could allow limited differential movement between adjacent rods. Limited slippage could reduce stresses without crack growth. The minor components of enamel, protein remnants and water, have a profound plasticizing effect. As mentioned previously, the protein matrix behaves like a soft wrap around the mineral platelets and protects them from the peak stresses caused by the external load and homogenizes stress distribution within the composite structure. At the most elementary structure level, natural biocomposites exhibit a generic microstructure consisting of staggered mineral bricks. It was proposed that under an applied tensile stress, the mineral platelets carry the tensile load while the protein matrix transfers the load between mineral crystals via shear [80]. The strength of the protein phase in a biological material is amplified by the large aspect ratio of mineral platelets. Besides, the larger volume concentration of protein significantly reduces impact damage to the protein–mineral interface (Fig. 1).

View Article: PubMed Central - PubMed

ABSTRACT

Alumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores), and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ) structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability.

No MeSH data available.


Related in: MedlinePlus