The mechanism of action of bioactive dental zirconia blocks

The mechanism of action of bioactive dental zirconia blocks

Bioactive dental zirconia blocks, through material modification technology, endow traditional zirconia with bioactive functions. The mechanism of action is mainly reflected in the following aspects:

1. Surface morphology and microstructure optimization

Roughness control

By means of sandblasting, laser treatment or chemical etching, micrometer-scale or nano-scale rough structures are fabricated on the surface of zirconia to increase the material's surface area and promote cell adhesion and bone integration. For instance, laser treatment can form micro-groove structures on the surface of zirconia, significantly enhancing the adhesion and proliferation of bone cells.

Porous structure

The introduction of porous structures (such as pore diameters of 50-200μm) can provide growth space for bone tissue, promote vascularization and the entry of bone tissue, and enhance the mechanical locking between the implant and the bone tissue.

2. Surface chemical modification

Hydroxylation treatment

Hydroxyl groups (-OH) are introduced onto the surface of zirconia through heat treatment or chemical treatment to enhance the surface hydrophilicity and promote protein adsorption and cell adhesion. For instance, hydroxylation treatment can reduce the surface contact Angle of zirconia to below 20°, significantly enhancing the cell adhesion ability.

Ion doping

Bioactive ions such as calcium (Ca), phosphorus (P), and magnesium (Mg) are doped into zirconia to simulate the chemical composition of natural bone and promote the differentiation and mineralization of bone cells. For example, calcium-doped zirconia can release Ca²⁺ ions, activate the osteoblast signaling pathway and accelerate bone integration.

3. Bioactive coating

Hydroxyapatite (HA) coating

Hydroxyapatite was coated on the surface of zirconia to promote the adhesion and growth of bone cells by taking advantage of its similarity to bone tissue. The HA coating can be prepared by plasma spraying, electrochemical deposition or sol-gel method, and the thickness is usually 50-200μm.

Bioactive glass coating

Bioactive glass (such as 45S5 Bioglass) coatings can release ions such as Si, Ca, and P, which react with body fluids to form hydroxyapatite layers, promoting the combination of bone tissue and implants.

4. Antibacterial performance

Antibacterial ion release

Antibacterial ions such as silver (Ag) and zinc (Zn) are doped into zirconia to inhibit bacterial growth through ion release. For example, silver ion-doped zirconia can effectively inhibit the growth of Staphylococcus aureus and Streptococcus mutans, and reduce the risk of peri-implantitis.

Surface antibacterial coating

Antibacterial coatings (such as those containing silver nanoparticles) are applied to the surface of zirconia to kill bacteria through physical or chemical actions and reduce the formation of biofilms.

5. Protein adsorption and cell signal regulation

Surface-modified protein

Fix extracellular matrix proteins (such as collagen and fibronectin) on the surface of zirconia to promote cell adhesion and migration. For example, the collagen-modified zirconia surface can significantly enhance the proliferation and differentiation ability of osteoblasts.

Growth factor loading

Growth factors such as bone morphogenetic protein (BMP) and vascular endothelial growth factor (VEGF) were loaded onto the surface of zirconia to promote bone tissue and angiogenesis through sustained release.

6. Stress-induced phase transformation toughening

The transformation from tetragonal phase (t-ZrO₂) to monoclinic phase (m-ZrO₂) :

When zirconia is subjected to stress, the tetragonal phase transforms into the monocline phase, accompanied by volume expansion (3%-5%), consuming the energy for crack propagation and playing a toughening role. This phase change toughening mechanism can enhance the fatigue resistance of zirconia and prolong the service life of implants.

7. Biocompatibility and immune regulation

Low cytotoxicity

Zirconia has good biocompatibility and does not cause obvious cytotoxicity or immune responses. Its surface modification can further reduce the inflammatory response and promote tissue healing.

Immune regulation

Some modified zirconia materials (such as strontium-doped zirconia) can regulate macrophage polarization, promote the generation of M2-type anti-inflammatory macrophages, and inhibit peri-implant inflammation.

8. Long-term stability and bone integration

Corrosion resistance

Zirconia has excellent corrosion resistance and can maintain stability for a long time in the oral environment, reducing bone resorption caused by the release of metal ions.

Osteointegration promotion

Through surface modification and bioactive coating, zirconia implants can form a tight bond with bone tissue, achieve early osseointegration, and increase the success rate of implantation.

Summary

Bioactive dental zirconia blocks significantly enhance the biological activity and osseointegration ability of zirconia through multiple mechanisms such as surface morphology optimization, chemical modification, bioactive coating, antibacterial treatment, protein adsorption and cell signal regulation. These modification techniques have enabled zirconia implants to perform outstandingly in terms of mechanical properties, biocompatibility and aesthetic effects, making them ideal materials in modern dental restoration and implant fields.