Prosthetic IV. Partial removable dentures Class I. And II. Ways of the transfer of masticatory forces • Teeth • Teeth and oral mucosa 􀂾 • Oral mucosa Teeth and/or oral mucosa Bone Removable partial dentures classification • Class I. Dental arch with gaps (interruptions) interruptions • Tooth borne dentures • Class II. Reduced (shortened ) dental arch Tooth and tissue borne dentures Removable partial dentures classification • Class III. Residual dentition Tissue born dentures, plate dentures • Class IV. Complete denture Tissue born dentures Components • Base (basis) • Elements of anchorage • Clasps: casted clasps, wire clasps, combined clasps • Anchorage supporting bar • Attachements • Telescope crowns Base (basis) • Replaces missing part of alveol and carry arteficial teeth • Supports the supplied teeth and effects the transfer of occlusal stresses to the supporting oral structures • Different materials – • + (framework) resin attached to the metal framework metal framework or resin only Base • Accuracy of adaptaion to the tissues with low volume change • Dense, non irritating surface that is capable of receiving and maintaining a good finish • Thermal conductivity • Low specific gravity • Sufficient strength – resitance to fracture • Easily kept clean • Aesthetics acceptability • Potential for future relining • Low initial cost Components • Teeth - acrylic teeth - porcelain teeth Clasps Surface retainers –they lie on the surface of teeth Tha parts are called arms: One, two or three arms Clasps • One arm made of wire • Simple retainer, only in simply temporary • prothesis • It can damage the tooth because of no stabilization (bracing) Clasps • Two arms clasps • One arm for retention (wire) wire • One arm for stabilization against horizontal forces Clasps • Three arms clasps One arm for retention (wire) wire One arm for stabilization (bracing) against horizontal forces One arm (the rest) for transmission of occlusal forces Rests • Any unit of a partial denture that rests upon • (premolar, premolar molar) vertical support to the denture is called a rest • Upon the occlusal surface molar • Upon the lingual surface (prepared) of anterior teeth Rests • Transmitted forces parallel to the long axis of the tooth will prevent movement in a cervical direction. Components • Connectors Connect the parts of denture • Major • Minor Major connector • Connect the parts of the prothesis All of its parts are directly or indirectly connected with it Must be rigid -stresses are efectively distributed Over the entire area Mandibular major connector • Lingual bar • Lingual plate ( continouos bar retainer and lingual bar) Clasp – three armed cast One part for retention (going under the maximal convexity) One part for stabilization against horizontal forces (upon the maximal convexity) On arm for transmission of occlusal forces (the rest) Class I and II dentures with the metal framework Class I. denture Components: Metal framework Base Clasps Arteficial teeth Class I and II dentures with the metal framework Lingual plate Class I and II dentures with the metal framework Anterior palatal bar Posterior palatal bar Minor connector Sequences of operations Taking impressions (alginate. Both jaws always ! Sequences of operations Pouring – gypsum models. Fabrication of the individual impression tray if necessary. If not, fabrication of the bite template: The bite template is necessary for The registration of the intermaxillary Relationship. It consist of the shellack base and the wax walls. Wax walls Shellack base Sequences of operation • Registration of the intermaxillary relationship. The registrate Sequences of operation • Preparation of the model for backup. All undercuts are blocked out Also the space under the future framework Using heated wax Sequences of operations • Backup using the reversibile impression agar based material in a special flask • Pouring of this impression with -the investing material – casting model Sequences of operations • Fabrication of the wax pattern of the metal framework. Influx system Sequences of operations • Investment with the same investing material – a special flask. The wax is burnt out and the form is heated in a special oven. After that the casting process is performed using a special casting machine. Sequences of operation • After casting and cooling the framework is taken out, the inflow system must be cut off. Sequences of operation • The cast is grinded, polished and adapted on the former gypsum model The final framework is tried out Sequences of operation • The arteficial teeth will be applied acc. to intermaxillary registrate in articulator. Arteficial teeth - acrylic Sequences of operation • After trying out of the denture with wax base and teeth the denture is completed The framework with the wax pattern of the base and teeth has been put into a flask, the wax has removed and replaced with a resin dought. The resin base is polymerized using heating. Sequences of operation • The denture is finished, polished and tried in. Feedback • For which classes of removable dentures is necessary to fabricate the metal framework? • On which model is the wax pattern of the framework made? • What is the method of „lost wax“ ? Feedback • Which parts does the partial removable denture consist of? • Describe the sequences of operations of these dentures. Explain the main difference between class I. and II. removable dentures. • What is the purpose of the bite template? Which part does it consist of? • Explain the term „investment“ .