Types Of Dental Implant Materials

Types Of Dental Implant Materials

Write a short note on the classification and materials used in implants.
Answer:

Classifiation of Implants:

1.  Based on the Materials Used:

• Metals and alloys: It consists of titanium and its alloys, stainless steel, cobalt-chromium, and molybdenum
• Ceramics and carbon implants: Made of carbon with stainless steel
• Polymers and composites: Polymethylmethacrylate and polytetrafluoroethylene.

2. Based on biological response:

• Biotolerant: Such materials are not easily rejected when implanted in living tissue and are surrounded by firous layer in the form of a capsule, for example
  • Metals such as gold, cobalt–chromium alloy, stainless steel, zirconium, niobium
  • Polymers like polyethylene, polyamide, polymethylmethacrylate, and polyurethane.
• Bioinert: These materials allow close apposition of bone over their surface causing contact osteogenesis. Examples are:
  • Metals such as commercially pure titanium and titanium alloy
  • Ceramics like aluminum oxide and zirconium oxide
• Bioactive: These materials allow the formation of bone on their surface, but the exchange of ion along with host tissue causes the formation of the chemical bond at interface.
• Examples are: Ceramics like HA, b-tricalcium phosphate, bioglass, fluorapatite, and carbon–silicon.

3. Based on Histology:

• Osseointegrated
• Non-osseointegrated.

4. Based on the Design of the Implant:

• Endosteal implants: They are placed in the alveolar or basal bone of the maxilla and mandible, and they transect only one cortical plate, for example, Blade implants and ramus frame implants.
• Subperiosteal implant: It consists of an implant substructure which is a custom-cast frame placed directly over the bony cortex just below the periosteum.
• Transosteal implant: It penetrates both cortical plates, for example, the Transmandibular implant, and mandibular staple implant.

5. Based on Macroscopic Design:

• Threaded or threadless
• Cylindrical or conical
• Hollow or solid.

6. Based on surface treatment:

• Titanium plasma-sprayed
• Aluminum oxide coated
• Hydroxyapatite coated
• Machined
• Blasted or etched with biomaterials
• Electropolished.

Materials used in Implants:

• Metals: Stainless steel, cobalt-chromium-molybdenum, titanium alloys and surface coated titanium
• Ceramics: Hydroxyapatite, bioglass, aluminum oxide
• Polymers and composites
• Others: Gold, tantalum, carbon, etc.
• Stainless Steel: Austentic steel is used as implant material. It has high strength and ductility so is rarely used.
• Titanium: Titanium as implant material is most commonly and widely used. Titanium and its alloys are of the following types, i.e.
  1. Commercially pure titanium (CpTi)
  2. Titanium–6 Aluminum–4 Vanadium (Ti–6Al–4Va).

 1. Commercially Pure Titanium: Based on iron content commercially pure titanium is differentiated in four grades. It ranges from 0.2% to 0.5% from Grade 1 to Grade 4

• Microstructure: It consists of two phases, i.e.
  • Hexagonal close-packed, i.e. alpha phase
  • Body-centred-cubic, i.e. beta phase.
• Properties: Titanium has the property of passivation on contact with either air or tissue flid which decreases biocorrosion. Titanium is always covered by an external oxide layer, i.e. titanium oxide layer which is inert biologically and aids in osseointegration.
  • Its thickness is 2 to 10 nm
  • The modulus of elasticity of commercially pure titanium is five times more than compact bone.
  • Titanium is light in weight and its density is 4.51 g/cm.
  • The melting point of commercially pure titanium is 1668°C.
  • It has excellent biocompatibility.
  • Commercially pure titanium contains oxygen and a minor amount of impurities such as nitrogen, carbon, hydrogen, etc.

2. Titanium–6 Aluminum–4 Vanadium (Ti–6Al–4Va): This is the alloy form of titanium.

• Composition: Its composition is:
  • 90% Titanium
  • 6% Aluminum
  • 4% Vanadium.
• Properties:
  • Its modulus of elasticity is 5 to 6 times of compact bone.
  • It has the property of passivation on contact with air and tissue flids which is 60% stronger than pure titanium.

• Ceramics: They can be bioactive or bioinert. They are of limited use because of low tensile strength and ductility. They are used as surface coats on titanium implants.
• Polymers and Composites: They are fabricated in porous and solid forms for tissue attachments and replacement augmentation. In some of the implants, they are mainly used within the implants as connectors for stress distribution.
• Other Materials: Gold, tantalum, carbon, etc. materials were used in the past. Recently zirconia and tungsten are used. Carbon was recently used as coatings for metallic and ceramic devices.