Polymers Used In Dentistry Question and Answers

Dental Polymers Important Notes

1. Types of polymerization

  • Condensation polymerization
    • Involves combining two dissimilar molecules into a third entirely different product
    • Ex: phenol and formaldehyde to form Bakelite
  • Addition polymerization
    • When similar molecules are combined the reaction is called an addition reaction
    • In it, the monomer is repeated many times to form a polymer
    • No by-products are formed
    • Example: polymethylmethacrylate

2. Stages of polymerization

  • Initiation
  • Propagation
  • Termination
  • Chain transfer

3. Copolymerization

  • Resin formed by two or more chemically different monomers is called copolymer
  • The process of formation is called copolymerization

Read And Learn More: Dental Materials Question and Answers

Polymer And Monomer In Dentistry

Dental Polymers Long Essays

Question 1. Describe polymerization mechanisms. Add a note on stages in addition to polymerization.


  • It is the chemical reaction in which monomers of low molecular weight are converted into chains of polymers with a high molecular weight
  • Monomer + Monomer + Monomer+ → Polymer
  • These monomers are connected by bonds
  • It is a repetitive intermolecular reaction

Polymerization Types:

1. Condensation polymerization

  • It is divided into two groups
    • Those in which polymerization occurs along with the repeated elimination of small molecules
    • Those in which functional groups like amide, and ester are repeated

2. Addition polymerization

  • In this type of polymerization, monomers are repeated and every time one molecule is added the chain continues
  • There is no change in chemical composition and no by-products are formed

Inhibition of Polymerization:

Polymerization is inhibited by

Polymer And Monomer In Dentistry

1. Impurities

  • Any impurity in the monomer that can react with free radicals inhibits or retards the polymerization
  • It occurs during storage
  • Example: The addition of a small amount of hydro-quinone inhibits polymerization

2. Oxygen

It reacts rapidly with free radicals and retards polymerization

Stages of Addition Polymerization:

There are four stages of addition polymerization

1. Induction

  • It is the time during which the molecules of the initiator become activated
  • It is the activation of free radicals which in turn initiate growing polymer chains
  • Thus, this stage is controlled by activation and initiation
  • Any impurities present increase the length of the induction period
  • It is useful for dental resins
  • These resins are activated by heat, chemicals, and light

Dental Polymers Stages Of Addition Polymerization

  • Example: Amine acts as an activator and benzoyl peroxide as an initiator for dental resins

2. Propagation

  • It is a stage of polymerization during which polymer chains continue to grow to high molecular weights
  • It is accompanied by the liberation of heat. Thus it is an exothermic reaction
  • The growth of the polymer chain stops if the reactive center is destroyed by the termination reaction

3. Chain transfer

  • During this stage, the growing end of a chain is transferred to another molecule and initiates further chain growth
  • Here the active state is transferred from active radical to inactive molecule

Polymer And Monomer In Dentistry

4. Termination

It occurs through two processes

  • Direct coupling of two free radical end chains
    • The two molecules combine and become deactivated by the formation of a covalent bond
  • Exchange of hydrogen atom
    • The hydrogen atom is transferred from one growing chain to another
    • A double bond is produced between them

Polymers Used In Dentistry

Dental Polymers Short Question And Answers

Question 1. Copolymerization


  • It is the process of polymerization where two or more chemically different monomers combine to form polymers called copolymers.
  • There are three different types of copolymers

Polymer And Monomer In Dentistry

  1. Random type
  2. Graft type
  3. Block type

Importance of Copolymerisation:

It is used to improve the physical properties of resins

Dental Polymers Importance Of Copolymerisation

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