بسم الله الرحمن الرحيم
Minor ConnectorsMinor Connectors
Connects components to the major connectorDirect retainer
Indirect retainer
Rest
Requirements of minor connector:
1.sufficient rigidity . Like the major connector, the minor connector must have sufficient bulk to be rigid to transmit forces between the linked components.2. must not impinge on marginal gingival tissues. Slight relief is required when crossing the gingival margin especially in tooth-mucosa borne dentures.
3.Minor connectors should be located at least 5mm from other vertical components.
Functions of Minor Connectors
1. Unification and rigidity2. Stress distribution
3. Bracing through contact with guiding planes4. Maintain a path of insertion
Types of Minor Connectors
Embrasure Minor ConnectorsBetween two adjacent teeth
Embrasure Minor Connectors
Triangular shaped in cross sectionJoins major connector at right angles
Relief placed so connector not directly on soft tissue
Proximal minor connector:Those that join the clasp assembly to the major connector.If the minor connector is located on a proximal surface of a tooth adjacent to edentulous areas, it should be broad buccolingually to provide strength but thin mesiodistally to minimize encroachment on the saddle area.
mesial and distal minor connectors and proximal plates adjacent to the edentulous areas should swing back to join the major connector in a rounded acute angle in order to increase gingival exposure.
Latticework construction,
Mesh construction,Bead, wire, or nail-head minor connectors .
Gridwork minor connectors that connect the denture base and teeth to the major connector.
Gridwork Minor ConnectorsOpen lattice work
mesh typesMesh type
Flatter
Potentially more rigid
Less retention for acrylic if openings are small
Lattice Type
Potentially superior retentionInterferes with setting of teeth, if struts are too thick
This type can be relined easily after ridge resorption.
Bead, wire, or nail-head minor connectors
no relief is provided for this type of minor connector.It cannot be relined if ridge resorption takes place. It should be used on tooth-supported ridges.
Gridwork Relief
Usually one thickness of baseplate wax is about
1 mm of relief sufficient
the space provided by the relief wax is available for the mechanical retention of the acrylic resin
The minor connector for the mandibular distal extension base should extend posteriorly about two-thirds the length of the edentulous ridge and should have elements on both lingual and buccal surfaces.
Mandibular Gridwork Design
Minor connectors for maxillary distal extension denture bases should extend the entire length of the residual ridge and should be of a ladderlike and loop design.
Those that serve as an approach arm for a vertical projection or bar-type clasp.
Finishing Lines
The junction of gridworks to the major connector should be in the form of a butt joint with a slight undercut in the metal. The angle formed by the metal at this juncture must not be greater than 90 degrees.If these butt joints occur on the outer aspect of the major connector they are called external finish lines; if they are on the internal or tissue side of the major connector ,they are internal finish lines .
Angle the finish line forms with major connector – less than 90 degree.
Finish line located too far medially– natural contour of palate altered by thickness of acrylic Too far buccally– difficult to create a natural contour of acrylic resin on lingual surface of artificial teeth
90-degree butt-type joints
Tissue stop : a small projection of metal at the distal end of an extension base frame that contacts the cast and prevents downward movement of the plastic retention area during packing with resin
Closure of the flask under hydraulic pressure cancauses distortion of the framework, pushing ittissue ward.