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PROSTHODONTICS LECTURE / 1st TERM / DMD4...

PROSTHODONTICS LECTURE / 1st TERM / DMD4 Dr. Dyna Jeanne D. Godoy RPD FRAMEWORK RPD METAL FRAMEWORK MAJOR CONNECTOR The unit of a removable partial denture that connects the parts of one side of the dental arch to those of the other side. Its principal functions are to provide unification and rigidity to the denture. MINOR CONNECTOR A unit of a partial denture that connects other components (i.e. direct retainer, indirect retainer, denture base, etc.) to the major connector. The principle functions of minor connectors are to provide unification and rigidity to the denture. DIRECT RETAINER Components of a typical removable partial denture A unit of a partial denture that provides retention against dislodging forces. A direct retainer is commonly called a 1. Major connectors 'clasp' or 'clasp unit' and is composed of four elements, a 2. Minor connectors rest, a retentive arm, a reciprocal arm and a minor connector. 3. Rests INDIRECT RETAINER 4. Direct retainers (rest, clasps, retentive arm, stabilizing A unit of a Class I or II partial denture that prevents or component, reciprocal arm) resists movement or rotation of the base(s) away from the 5. Stabilizing or reciprocal components (as parts of a residual ridge. The indirect retainer is usually composed of clasp assembly) one component, a rest. 6. Indirect retainers (if the prosthesis has distal extension DENTURE BASE bases) The unit of a partial denture that covers the residual ridges and supports the denture teeth. 7. One or more bases, each supporting one to several replacement teeth REST Rest – vertical support (retention, stability, support) a. Major Connector  A rigid extension of partial denture which contacts a remaining tooth to transmit vertical b. Minor Connector forces c. Direct Retainer  A rigid component resting in a recessed preparation on the occlusal, lingual or incisal d. Indirect Retainer surface e. Denture Base a. Occlusal rest - a rest placed on the occlusal surface of a bicuspid or molar. b. Lingual (cingulum) rest - A rest placed on the cingulum of an anterior tooth (usually the canine). Rests may also be placed on the lingual of posterior teeth by creating a ledge of the tooth surface (prescribed for surveyed crowns). c. Incisal rest - A rest placed on an anterior tooth at the incisal edge. d. Intracoronal (precision) rest - A rest consisting of precision manufactured attachments that are placed within the coronal contours of a crown or retainer. Page 1 of 6 (CHRISBEL JOYCE FRANCISCO)  MIDTERM LESSONS – CHRISBEL JOYCE FRANCISCO NATIONAL UNIVERSITY – MALL OF ASIA PRIMARY PURPOSE TYPES OF REST SEATS  To provide vertical support for the PD 1. Occlusal rest  Conventional FUNCTIONS o Extended 1. Maintains components in their planned positions o Onlay 2. Maintains established occlusal o Embrasure relationship by preventing setting 2. Incisal Rest of the denture 3. Lingual Rest 3. Prevents impingement of the soft  Cingulum tissues o Ball 4. Directs and distributes occlusal loads to the abutment teeth OCCLUSAL REST A. Conventional REQUIREMENTS DESIGN CONSIDERATIONS  Rest seats should have an approximately 1.5mm 1. Sufficient thickness of metal to prevent fracture, reduction of the marginal rides especially of the junction of the rest and the minor connector (1.5mm for chrome cobalt, 2mm for gold)  Spoon-shaped/rounded triangular shape with apex toward the center of the tooth 2. Should be placed on surfaces which would direct forces along the long axis of the teeth, should not be placed on inclined surface 3. Should be extended to or close to the center as feasible to promote axial direction of faces 4. Should be placed in rest seats which smooth and rounded internal line angle 5. Rest seat should be enamel or any restoration  Should be long as it is wide that has been proven scientifically to resist  Base is about 2.5mm fracture and distension when subjected to  Angle formed by the rest and truss arm =