Soft Liners in Dentistry: Types, Composition, Uses, and Benefits

Soft Liners In Dentistry

Soft liners are soft cushion like liners which are given to the denture base to absorb some of the energy produced by masticatory impact and to distribute the forces of mastication more evenly.

Types Of Denture liners

1. Short-term soft liners (ISO 10139 Part 1)
2. Long-term soft liners (ISO 10139 Part 2)

1. Short-term Soft Liners:

They are also known as temporary liners.

Composition Of Short-term Soft Liner

• Powder:
  • Prepolymerized spheres of PMMA
  • Benzyol peroxide—initiator
  • Color pigments
  • Inorganic salts
• Liquid:
  • Methyl methacrylate
  • Dibutyl phthalate (50 to 60%)—plasticizer
  • Tertiary amine—activator
  • Hydroquinone—inhibitor
  • Liquid: Mixture of ethyl glycol + An aromatic ester, i.e. butyl glycolate or dibutyl phthalate.

Indications Of Short-term Soft Liner

• For relining an ill fitting denture which allows the tissues to return back to normal at which point a new denture can be made.
• As functional impression material.

Advantages Of Short-term Soft Liner

1. They have a high peel strength
2. They are rupture resistant.

Disadvantages Of Short-term Soft Liner

• They have poor resistance.
• They lose their plasticity in time.

Manipulation Of Short-term soft line

• The denture base is relieved on the tissue surface.
• Mix powder and liquid together to form a gel and place it on the tissue surface of the denture and insert it in the mouth.
• Gel flows readily to fil the space between the denture base and oral tissue.

2. Long-term Soft Liner:

They are also known as permanent soft liners. This is because they are used for extended periods from 6 months to 5 years.

Types Of Soft Liner

• Plasticized acrylic resin
• Plasticized vinyl resin
• Silicone rubbers
• Polyphosphazine

Indications Of Soft Liner

• In patients having highly resorbed or atrophied ridges.
• In patients having bruxism.
• For relining the prosthesis which is used to restore maxillofacial defects.
• To restore congenital or acquired oral defects.
• In patients suffring from xerostomia.

Advantages Of Soft Liner

• Abused tissues healed quickly.
• Patients adapt to dentures quickly.
• This creates the possibility of an immediate denture following extraction.

Disadvantages Of Soft Liner

• Poor resistance to wear.
• With time plasticizers leach out making them hard.
• Color stability is poor.
• Rough surface harbors certain microorganisms.