Re-lining materials Flashcards
Relining
Carried out when denture becomes ill-fitting due to bone resorption
Denture relining materials
Hard reline materials
Soft liners
Tissue conditioners
Softliners function
A permanent soft cushion for pxs who cannot tolerate a hard denture
Can be incorporated at time of production or added to existing denture
Relining steps
Remove undercuts and periphery chairside Take impression (ZOE or silicone) Send to lab, model cast Vertical dimension recorded Impression material replaced with wax Usual processing to replace wax with acrylic
Soft liner material
Plasticised heat cured acrylic e.g. Coe Super Soft Silicone rubber -cold cured e.g. Flexibase, TSR -heat cured e.g. Molloplast-B Silicone/ acrylic co-polymer e.g. Flexor
Tissue conditioners (visco-gel)
Temporary soft cushion to allow traumatised tissue to recover before carrying out definitive treatments/ taking imps for a new denture
Hard reline materials
To replace fitting surface and improve the fit of an existing denture
Repairs, extensions, fixing artificial teeth to the denture base
Criteria for relining/ rebasing with hard reline materials
Poor retention and stability
Collapse of vertical dimension
Degeneration of denture base surface
Lack of proper extension
Types of hard reline materials
Chairside -cold cure acrylic -light cured composite Laboratory -heat cured acrylic
Cold cure acrylic
Powder: PMMA, Liquid: MMA & di-n-butylphthalate
-improves flow but reduces Tg
Powder: Polyethyl methacrylate, Liquid: Butyl methacrylate
-less irritant but lowers Tg considerably
Problems with cold cure acrylic
Remove too soon --> distortion Exothermic reaction Remove too late --> mucosal damage Porosity Residual monomer No control over thickness of reline Unacceptable taste for some products Poor colour retention
Requirements for soft liner
Low elastic modulus Retain low elastic modulus High resilience Good adhesion to denture base High tear strength Biocompatible Antibacterial Dimensionally stable Good surface wettability
Types of soft reline materials
Plasticised heat cured acrylic e.g. Coe Super Soft Silicone rubber -cold cured e.g. Flexibase, TSR -heat cured e.g. Molloplast-B Silicone/ Acrylic co-polymer e.g. Flexor
Relative merits of silicone based soft liners
Highly resilient Retain softness Weak bond to acrylic Susceptible to growth of candida Poor tear strength No permanent deformation Poor wettability Needs regular replacement
Relative merits of acrylate based soft liners
Not as resilient as silicones Go hard with time due to leaching of plasticiser Resistant to bacterial growth Excellent bond to acrylic Acceptable tear strength Susceptible to creep Good wettability Needs regular replacement
