MAJOR CONNECTORS PDF

MAJOR CONNECTORS Bony or soft tissues prominence should be avoided during placement and removal....

MAJOR CONNECTORS Bony or soft tissues prominence should be avoided during placement and removal. o Bony prominences such as Torus Palatinus and Torus Mandibularis Must not impinge on the free gingiva because of superficial blood supply. MAJOR CONNECTORS Borders are placed at least 6mm from the Component of an RPD that connects the one free gingival margins. side of the arch with those on the opposite side When a 6 mm distance from the gingival It is the unit of the RPD to which all parts are margins cannot be obtained, the metal may directly or indirectly attached. be extended to the cingulum, of the anterior It provides a rigid union of all portions of the teeth or to lingual surfaces of the posterior prosthesis. teeth. 2mm anterior from fovea palatinae FUNCTIONS OF A MAJOR CONNECTOR No relief of the maxillary major connector is 1. Unification necessary except for torus, median raphe o unites all other components of a partial (due to deep blood supply, glandular zone denture so that the removable partial and fat zone). denture acts as one Metal should not have a high polish on tissue 2. Stress Distribution surface in order to preserve intimate tissue o distribute functional loads to all abutment contact. teeth so that no single abutment is All borders should be smooth and follow subjected to extreme loading. contour of surrounding structure/s to be less 3. Cross-Arch Stabilization perceptible to the patient. o By uniting one side of the arch to the other bracing elements on one side of the arch can aid in providing stability to the other. This prevents twisting and torqueing forces. REQUIREMENTS / DESIGN CONSIDERATIONS In the rugae region, the border should pass Must be rigid to transmit forces from one side through the valleys of the rugae when of the arch to the other possible (to avoi bulky feeling). o Forces applied may be effectively distributed over the entire area o Resists flexing and torque that would otherwise be transmitted to abutment teeth as destructive forces 1  The posterior border should not extend onto the movable tissues (the posterior limit should be at the vibrating line). Borders should be beaded to prevent the food ingress and to reduce patient awareness. The palatal extension of the internal finish line determined primarily by the need to reline the partial denture to compensate from anticipated bone resorption. When future loss of natural teeth is anticipated a plate type may be used. MAXILLARY o 4-6mm away from the free gingiva. RIGIDITY o Soft Palate Definition: MANDIBULAR o It is necessary to control relationship of o 4mm away from the free gingiva. remaining teeth to each other. Control o Tongue and Floor of the mouth. direction. MINIMIZE FOOD IMPACTION o Necessary to ensure that the partial Locate margins away from the free gingival denture functions as one unit. If the denture margin flexes, stress distribution and cross arch Eliminate “traps” or large concavities where stabilization can be compromised since food can collect different portions of the denture can move UNOBTRUSIVE independent of the others. Smooth transition from the connector to the A major connector can be made more rigid denture base by: All line angles and edges should be smooth a. using a more rigid alloy (Chrome-cobalt > and rounded. gold alloys; cast > wrought metal) Bulk should be reduced enough so as not to b. using a 1/2 round or 1/2 pear shaped bars interfere with speech or appearance (more rigid than flat bars) BEADING OF THE CAST c. increasing the bulk as the length increases Bead around major connector d. corrugating linguo-plate or rugae areas. Scribing of a shallow groove on the maxillary master cast outlining the palatal major connector exclusive of rugae areas Purpose: 1. To transfer design to the investment cast NON-INTERFERENCE WITH THE SOFT TISSUES 2. To provide a visible finishing line for the Major connectors shouldn’t enter undercut casting areas – tissue impingement should be 3. To ensure intimate tissue contact of the avoided major connector with selected palatal Undercut block-out tissues Major connectors should be as far from the free gingival margin as possible Before a partial denture design has been finalized, the clinician should make a careful examination of the mouth to ensure the selected major connector or other components will not interfere with any anatomical structures ✓ Attached Gingiva ✓ Free Gingiva MAXILLARY MAJOR CONNECTOR Failure to provide clearance will lead to: 1. Single Palatal Bar o Inflammation – Necrosis – Recession 2. U-shaped Palatal Connector 2 3. Single Palatal Strap AP Strap 4. Anterior-Posterior Palatal Bar Used for Class I, II, and/or IV cases 5. Anterior-Posterior Palatal Strap Maximum rigidity 6. Palatal Plate Minimum bulk Usually used: 2, 3, 5, 6 Used on most cases SINGLE PALATAL BAR Especially when patients have Torus Palatinus Must have concentrated bulk for rigidity Min. thickness 8mm Narrow antero-posteriorly Thick occluso-gingivally Palatal bar objectionable due to bulk Do not use (bars are not used because of thickness) !!! STRAP ✓ Palapad not pakapal ✓ Thinner occluso-gingivally ✓ Can be used for patients with torus palatinus (window) U-SHAPED PALATAL CONNECTOR ✓ If you have torus present, maneuver around U-Shaped/Horse-Shoe Shaped palatal ti. connector ANTERIOR-POSTERIOR PALATAL BARS Most objectionable A-P Bar/ Double palatal bar connector Use only where torus prohibits other Variation of anterior-posterior palatal strap connectors Requires greater bulk for rigidity Induces torque or lateral forces to abutment More objectionable to the patient teeth/residual ridges Strap connectors provide greater distribution Lack of support characteristics and may of stresses permit impingement of underlying tissues when subjected to occlusal loading Required bulk in the rugae area for rigidity (tongue requires freedom) PALATAL PLATE Full Palatal Plate/Palatal Vault Used for shallow palatal vault Maximum tissue support SINGLE PALATAL STRAP Maximum stress distribution Should be about 8mm in width Connector of choice in long distal extension Usually used for Class III cases cases Wide antero-posteriorly Six or less anterior teeth remaining on the Rigid, without objectionable bulk and arch interference to the tongue, provided this bulk Abutments are periodontally involved is distributed in three planes Mabigat kasi walang window ANTERO-POSTERIOR PALATAL STRAP 3  Not used in cases of Torus Palatinus Great stability and stress distribution Shape: Connector should: o Flat on tissue side o Be fabricated with uniformly thin metal o Convex or tear-drop on tongue side o Have accurate anatomic reproduction of o ½ pear shape, with thin edge towards the rugae teeth o Cover same area as complete denture o Occluso-gingival width: 4-6mm o Have a large surface area of mucosal o Thickness: 1.5-2mm contact (Improves strength and rigidity) o Thinner towards teeth Stay Plate: Interim Denture Acrylic resin can be used in interim prosthesis Position: 1. Let the patient lift the tongue to activate the floor of the mouth UNILATERAL RPD 2. Measure from tip of probe to free gingival Dangerous margin Can cause aspiration 3. Record values in chart-transfer to the cast Eliminate impingement MANDIBULAR MAJOR CONNECTORS o Wax spacer (Relief) placed under major 1. Lingual Bar connector 2. Linguoplate 3. Sublingual Bar 4. Cingulum Bar 5. Lingual bar with Cingulum Bar 6. Labial Bar Usually used: 1, 2 Less used: 3, 4, 5, 6 LINGUOPLATE/LINGUAL PLATE Lingual bar with extension over cingula of LINGUAL BAR anterior teeth Most commonly used Use where lingual bar cannot be used. Use whenever possible Prevents forces being directed facially Approximately 4 mm in width Rest at each end of plate Tapered on superior border/rounded on the A 4-6 mm clearance from the free gingiva inferior border (will not impinge on lingual could not be attained tissues when the denture bases rotate Superior border should fall on the supra- inferiorly under occlusal loads cingular surfaces of teeth. Terminal Rest – if possible; mesial side of 1st premolar or canine (upper), Lower (under 4  plate, can also function as an indirect Mandibular – 4mm from Gingiva retainer) o If can’t, extend occlusally / cingulum = Scallop shape – if may space then yung plate plate din. CONTINUOUS BAR RETAINER Indications: Kennedy Bar/Double Lingual Bar 1. Space for lingual bar is limited Lingual bar with secondary bar above 2. For flat ridges with low resistance to cingula horizontal rotational tendencies Secondary bar acts as indirect retainer 3. Splinting periodontally weakened teeth Not advisable – potential food trap between when used with rest on south adjacent two bards teeth ▪ Can buttress lower anterior against lateral and distal forces since the lingual surfaces of the maxillary anterior teeth contact the mandibular anterior in protrusive and lateral 4. When future replacement of one or more incisor teeth will be facilitated by the addition of retention loops to an existing LABIAL BAR plate. For lingually tipped teeth and for patients Variations: with lingual tori o May show through embrasures Swing Lock Design (Modified Version) SUBLINGUAL BAR More inferior and posterior in placement to the lingual bar Contraindicated for shallow floor of the mouth, high frenal attachment and tori o Missing key abutments such as canines o Excessive labial inclinations of anteriors o Unfavorable soft tissue contours – severe labial undercuts o Teeth with questionable prognosis – all remaining teeth function as abutments, the loss of tooth would seemingly not CINGULUM BAR compromise retention and stability to such When a linguoplate is the major connector of a degree choice, but the axial alignment of the o Contraindications of Swing Lock Design: anterior teeth is such that excessive block out ▪ Poor oral hygiene of interproximal undercuts must be made, ▪ Shallow labial / buccal vestibule this may be considered. ▪ High frenal attachment Maxillary – 6mm from Gingiva 5  REQUIREMENTS AND DESIGN CONSIDERATIONS 1. 3-4mm clearance from the free gingiva 2. 2. If clearance can’t be obtained, the metal should extend onto the cingula of the anterior teeth and on to the lingual surfaces of the posterior teeth 3. Relief of the tissue surface of major connector is required to prevent tissue impingement at rest or during function (more relief for tooth mucosa borne) ✓ Less relief – if fulcrum line is posterior to major connector ✓ More relief – if fulcrum line is anterior to major connector 4. Metal should be highly polished on the tissue side to prevent plaque accumulation. CHARACTERISTICS OF A BIOLOGICALLY DESIGNED MAJOR CONNECTOR 1. Alloy compatible with oral tissues 2. Rigid and uses principles of broad distribution of stress 3. Not irritating nor interfering with the tongue 4. Does not substantially alter the natural contour of the lingual surface of the mandibular alveolar ridge of the palatal vault 5. Does not impinge on oral tissues 6. Covers no more tissues than is absolutely necessary 7. Does not contribute to food impaction 8. Has support from other elements of the framework to minimize rotation tendencies in function 9. Contributes to the support of the prosthesis 10. Components resting on unprepared tooth surfaces can lead to slippage of the denture along inclines, to orthodontic movement of tooth or both 6