Dental Implant Materials Question And Answers

Dental Implant Materials

Question 1. Classify different implant materials used in the field of dentistry. Write in short about titanium as an implant material.
Answer:

A dental implant is a material or device placed in and/ or on oral tissues to support an oral prosthesis.

Classification of Different Implant Materials Used in the Field of Dentistry:

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.

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2. Based on biological response:

• Biotolerant: Such materials are not easily rejected when implanted in living tissue and are surrounded by fibrous 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, 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 onto their surface, but the exchange of ions along with host tissue causes the formation of the chemical bond at interface.
• Examples are: Ceramics like hydroxyapatite (HA), tricalcium phosphate, bioglass, fluorapatite, and carbon–silicon.

Titanium as Implant Material:

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 centered cubic, i.e. beta phase.
• Properties: Titanium has the property of passivation on contact with either air or tissue fluid 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 fie times more than compact bone.
  • Titanium is light in weight and its density is 4.51 gm/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.

Metal with Surface Coatings:

• The new implant design used in titanium is plasma sprayed or coated with thin layer of calcium phosphate ceramic or hydroxyapatite to produce bioactive surface which promotes bone growth. Her bond is chemical in nature as bone integrates with the coated surface.
• In this, a porous or rough titanium surface has been fabricated by plasma spraying in powder form of molten droplets at 1500°C temperature.
• Porous titanium surface from various fabrication methods
  may increase the total surface area (up to several times), produce attachment by osteoformation, enhance by increasing ionic interactions, and introduce a dual physical and chemical anchor system, and increase the load-bearing capability from 25% to 30%.
• The coatings have been applied to a wide range of endosteal and subperiosteal dental implants with the overall intent of improving implant surface biocompatibility profiles and implant longevities.