Teeth plays an important role in the digestive system which helps in breaking down food and supporting the overall digestive system. It is the hardest part of the human body; however, the tooth enamel is constantly exposed to wear which occurs from chewing, brushing, and acidic foods. Currently, the modern diets and poor dental care contribute to common dental issues like tooth decay which results in artificial teeth or dental implants. This implant replaces damaged or lost teeth and helps in maintain the normal function. The main challenge in dental implants and restorations is creating materials that match the toughness and biocompatibility of natural teeth. Researchers have continually worked on developing ideal materials, focusing on key factors such as durability, biocompatibility, wear and corrosion resistance, and aesthetic appeal.
Dental materials have evolved from metals and ceramics to modern composites, classified into four main categories: metal alloys, ceramics, composites, and noble materials. Titanium is the most widely used metal for dental implants due to its toughness, corrosion resistance, wear resistance, and high biocompatibility. It has a tensile strength of about 300 MPa and an elastic modulus of 110 GPa. Titanium also shows low cytotoxicity and minimal element release in biological environments. However, fretting wear remains a major issue, often leading to implant failure. To address this, various surface modification techniques have been explored to improve the performance of titanium implants.
Surface treatments for titanium and its alloys for dental implants
| Type | Method | Process Parameters | Attributes | Advantages | Limitations |
| Chemical | Chemical etching | 10% HF at 45 °C for 15 min | Ra ≈ 2 μm | Enhances biocompatibility, bioactivity, corrosion resistance | Requires precise etchant concentration and temperature |
| Hydrogen peroxide treatment | 30% H₂O₂ for 10 min | ~10% wear resistance increase | Improves wear and corrosion resistance | Reduces bioactivity | |
| Anodic oxidation | 20 V, 0.5 M H₃PO₄ electrolyte | 200 nm oxide layer | Enhances tissue interaction via immobilized biomolecules | Weak adhesion with surface | |
| Biochemical | Biomolecular cues | Varies | Improved surface adhesion, wear resistance | Boosts wear resistance, biocompatibility, and corrosion resistance | Uneven biomolecule release |
| HA/Calcium phosphate/alumina coatings | 600–700 °C coating temperature | – | Improves wear, blood compatibility, corrosion resistance | Weak HA/Ti bonding; requires phosphate/silane treatment | |
| Nanoscale organic monolayers | Varies | Ra < 1 μm | Enhances wear resistance, biocompatibility, corrosion resistance | Fragile under surgical conditions | |
| Biodegradable hydrogels | Room temperature coating | Thin and brittle | Sterilizes surface, removes oxide layer | Too thin and brittle for implantation | |
| Antibacterial agent application | Varies | Nonuniform coating | Prevents bacterial colonization | Difficult to ensure uniform density | |
| Physical | Plasma spray | Temp ~10,000 °C; 15 μm/min deposition rate | 100 μm thick HA coating | Alters micro/nano surface biochemistry | Coating can deplete in body fluids |
| Physical vapor deposition (PVD) | 400 °C, vacuum 1×10⁻³ Pa | ~2 μm coating, ~25% increased hardness | No chemical changes; preserves biological properties | Requires tight process control | |
| Ion implantation | Varies by ion/energy | Porous, bioactive surface | Enhances osseointegration | Not suitable for dental use | |
| Glow discharge plasma treatment | Varies | Thick oxidized porous surface | Bioactive, thick surface oxide layer | Complex parameters and high cost |
Ceramics are emerging as strong alternatives to metals in dental applications due to their superior biocompatibility, aesthetics, and favorable cellular response. However, their inherent brittleness and abrasive nature pose challenges, particularly the risk of fractures and wear on opposing teeth. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) stands out among dental ceramics for its high strength, fracture toughness, and excellent biocompatibility. To further improve performance, surface treatments such as laser processing, UV light exposure, ion implantation, and graphene coatings are used to enhance durability, reduce friction, and improve biotribological properties.
Advantages and challenges of using ceramics as dental implants
| Aspect | Details |
| Advantages | – High biocompatibility- Excellent aesthetic qualities- Favourable cellular response |
| Challenges | – Brittle due to crystalline structure- Prone to fracture from minor cracks- Abrasive to opposing teeth |
Composite materials, particularly polymer-based composites, are widely used in dental restorations and implants due to their chemical inertness, biocompatibility, aesthetic appeal, and ease of customization. Common polymers include PMMA, UDMA, PEKK, PEEK, Bis-GMA, and TEGDMA. However, a major drawback is their relatively poor wear resistance. To address this, research focuses on optimizing filler type, concentration, and configuration. Nanoparticles and microparticles have shown better enhancement of mechanical and tribological properties compared to fiber fillers, provided they are well-dispersed in the matrix. For example, reinforcing Bis-GMA/TEGDMA with 20% micro-sized tricalcium phosphate improved its elastic modulus and hardness more significantly than hydroxyapatite, due to the smaller particle size of tricalcium phosphate.
Advantages and challenges of using composites as dental implants
| Aspect | Details |
| Advantages | – Biocompatible and chemically inert |
| – Customizable formulations | |
| – Good aesthetic appearance | |
| – Easy to handle and implant | |
| – Compatible with various reinforcement fillers (nano/micro particles) | |
| Challenges | – Poor wear resistance compared to metals and ceramics |
| – Performance highly dependent on filler type, size, and dispersion | |
| – Nanoparticle dispersion in the matrix can be difficult to control | |
| – Larger filler particles (e.g., hydroxyapatite) may reduce mechanical strength | |
| – Long-term durability under oral conditions remains a concern |
Dental materials are subjected to various forms of wear, primarily affecting the enamel and dentin layers of the tooth crown. Enamel, being the outermost layer, is the first to experience wear, which can progress to the underlying dentin over time. Understanding the mechanisms and classifications of tooth wear is essential for the development of advanced dental materials. Current research is focused on creating materials that not only resist these tribological challenges but also mimic the biological functionality of natural teeth, ensuring durability, compatibility, and effectiveness in clinical applications.
[2] https://cascadedental.com/choosing-the-best-material-for-dental-implants-a-guide-for-patients/
