Dental Prosthesis 3rd Year Exam 8. Connectors PDF

3rd year prosthesis 8. connectors Major connectors: Minor connectors: it is a part to which all other is the connecting link between the major parts are directly or indirectly connector or base of a RPD and...

3rd year prosthesis 8. connectors Major connectors: Minor connectors: it is a part to which all other is the connecting link between the major parts are directly or indirectly connector or base of a RPD and the other units attached. of the prosthesis, such as clasps, indirect (connect 2 sides of the denture) retainers, and occlusal Role of Major connectors: ✓ Major connectors are an important component of removable partial denture; it is a part to which all other parts are directly or indirectly attached. ✓ It provides cross arch stability which helps to resist displacement by functional stresses. ✓ It contributes to the support and bracing of a partial denture by distributing functional loads widely to the teeth and to the mucosa, may contribute to indirect retention. Location: When designing major connectors these guidelines are followed: - Relief should be provided - Impingement of gingival tissue beneath a major connector to should be avoided. prevent its settling into areas of - Bony and soft tissue possible interference prominences should be avoided - Major connectors should be free during placement and removal of movable tissue. Requirement: 1. rigidity & strength 2. doesn’t interfere with tongue 3. doesn’t alter the natural contour of palatal vault or alveolar ridge 4. doesn’t impinge on oral tissue during insertion. removal & function. 5. minimal coverage 6. support 7. hygiene (decrease food trapping) = with beading  ❖ Forms of maxillary major connectors 1. Anterior-posterior palatal bars 2. palatal strap 3. horseshoe design 4. complete palatal coverage Bars Strap Plate 6-8 mm 8-12 mm Covers more than half Half rounded or half oval Thin uniform thickness of the palate cross section 1.Anteroposterior palatal bars: − The most rigid major connector − Used in almost any maxillary partial denture design (when torus is present) − The anterior component: flat bar located at least 6mm from gingival margin. − The posterior component: posterior bar with half oval cross section located as far posteriorly as possible (entirely on hard palate) − May cause patient discomfort &interfere with phonetics 2.palatal strap: >> Wide palatal bar: (wider & thinner) − more tolerated by patient − better distribution of stresses − increase retention by increasing surface tension minimum of 8 mm width mainly used for class III cases , the width of strap must increased in distal extension cases. 3.Horseshoe design: Horseshoe connector consists of a thin band of metal running along the lingual surfaces and cingula of the remaining teeth or at least 6 mm from gingival margin 2 Page − Used mainly when palatal torus present. 2  − When Vertical force applied to one or both ends of a horseshoe major connector, tendency for the connector to flex or deform. (connector must be rigid otherwise ➔ apply destructive forces to teeth and tissues) − Increase thickness to increase rigidity (discomfort & interference with phonetics) 4- Complete palatal coverage − Maximum coverage, maximum support and retention & maximum load distribution − Posterior border extends to the junction of hard &soft palate − Anterior border kept 6mm from gingival margin or cover cingula of teeth. Complete palatal coverage used with: 1. class I Kennedy (decrease stresses on abutments). 2. six remaining anterior teeth. 3. class III with modifications with poor condition of abutments no clasps used retention depend mainly on wide coverage (every denture). 4. patients with cleft palate. >> All acrylic, all cast metal or combination. ‫ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ❖ Forms of mandibular major connectors 1- Lingual bar 2- lingual plate 1.Lingual Bar: The simplest mandibular major connector limited converge, better tolerance Used when no need for indirect retainer or stabilization of remaining teeth Half pear shape in cross section with the thicker part at inferior border 3 Page Need at least 8 mm of sulcus depth 3  − Superior border (2-3 mm from gingival margin) − inferior border (above moving tissue of the floor of the mouth) − Follow the contour of lingual mandibular surface − should not contact mucosa when placed 2.Lingual plate: Indication of using lingual plate: 1. prescence of lingual tori. 2. abnormal high lingual frenum. 3. heavy calculus formation. 4. addition of anterior teeth expected. 5. need of indirect retention. 6. stabilizing periodontally weakened teeth. 7. need for horizontal stabilization in flat residual ridge. >> Gingival margin must be relieved to avoid irritation Notched lingual plate in case of diastema Minor connectors A MINOR CONNECTOR: is the connecting link between the major connector or base of a RPD and the other units of the prosthesis, such as clasps, indirect retainers, and occlusal rests. Minor connectors join the major connector with other parts of the RPD. Function: Join the parts of the RPD to the major connector so that the prosthesis acts as a single unit Forces applied to one part of the RPD are transmitted to other parts, and are dissipated by all teeth and tissues Transfers the effect of retainers, rests and stabilizing components to the rest of the denture 4 Page 4  Minor connectors Requirements: Borders should be beveled and smooth Rigid & not bulky Junction between minor &major connector should be rounded Must not be located on convex surface Gingival margin crossed by minor connector should be relieved Minor connectors Form and location: a. Proximal minor connector b. Denture base retention minor connector c. surface minor connector d. Embrasure minor connector Proximal minor connectors: Embrasure minor connectors: are usually termed PROXIMAL PLATES, are located between two teeth, it should be connect rests and clasp triangular in form so as to fit arms to the major in the embrasure. connectors Surface minor connector: The denture base retention minor connector: located on the lingual surface of is the means by which the acrylic denture incisors and canines. They base is mechanically attached to the connect lingual rests to the framework: retentive major connector. mesh, retentive lattice, loops, beads, and posts, 5 Page 5