1. RECENT MATERIALS FOR COMPLETE DENTURE
Disadvantages Acrylic Resins
1. Polymerization reaction shrinkage and dimensional changes (inherent)
affect in adaptation with tissues
2. Residual Monomer discoloration of acryl , porosity , cytotoxic effect of tissues , allergic reaction ,
low impact strength causing fracture of base
affect in biological and mechanical properities of material
N.b : heat cure are prefered more than self cure due to low amount of residual monomer
General advantages of Thermoplastic Resins
1. Thermoplastic base has more flexibility and softer surface compared to acrylic resins
Refers to Nylon
Flexibility is needed in cases of enlarged tuboristy and ridge undercuts
2. Can be used in patients who have an allergy to metal or PMMA
3. Hygienic advantages due to their low porosity and water absorption and solubility
4. Contain very little or almost no free monomer
5. Very high resistance to wear and solvent materials
6. Great toughness and strong resistance to fracture
7. Can be also reinforced in supporting areas by adding glass filler or fibers (can be modified )
General disadvantages of Thermoplastic Resins
1. Difficult finishing and polishing
2. Not bond chemically with acrylic teeth difficult repair , difficult relining
3. High cost
Types of thermoplastic resins (recent materials for complete denture)
1) Polyamide Polymer Nylon Flexible dentures
Flexible material are aesthetically good and more retentive because of their extensions into undercuts
which present lateral to maxillary tuberosity (more retentive)
Must be reinforced in supporting areas (denture base ) by using metal or peek to allow distribution of
forces
Available in the form of nylon granules in cartridges of varying sizes
Injection-molding technique is used
Acrylic teeth must be diatoric to allow mechanical bonding with nylon
2) High-Performance (rigid) Polymers The most commonly used high- performance polymer (HPP) is
polyetheretherketone (PEEK)
Metal-free prostheses to avoid the problem of bad esthetic , metal allergy and metal ions release
(cytotoxicity)
peek 19 megapascal but enough for rigidity and stress distribution … while titanium 120
PROSTHEASY
