Post on 14-Apr-2017
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Minor connectorsHiba HamidFinal year BDSGroup C
DEFINITIONIt is defined as:
The connecting link between the major connector or base of a removable partial denture and other units of the prosthesis, such as clasps, indirect retainers, and occlusal rests.
FUNCTIONS OF MINOR CONNECTORSConnects the major connector to other parts like clasps, rest, indirect retainers and denture bases.
Transmits stresses evenly to all components so that there is no concentration of load at any single point. This way forces applied to one part of RPD are transmitted to other parts and dissipated.
Transmits forces acting on the prosthesis to the edentulous ridge and the remaining natural teeth = Prosthesis to abutment function
Transfers effects of retainers, rests, and stabilizing components throughout the prosthesis = Abutment to prosthesis function
TYPES OF MINOR CONNECTORSJoins clasp assembly to major connectors
Joins indirect retainer or auxiliary rest to the major connector
Joins the denture base to the major connector
Serves as an approach arm for a vertical projection or bar type clasp
JOINING CLASP ASSEMBLY TO MAJOR CONNECTORSShould be broader bucco-lingually and thinner mesio-distally.
Should not be bulky so as to avoid tongue interference.
Rigid enough to support active components of partial denture like retentive clasp. Exception???
Since it is attached to the rest in the clasp assembly, it prevents tissue-ward movement of partial denture.
Triangular cross section with thickest portion at lingual line angle of tooth & thinnest portion at buccal line angle of tooth. This configuration aids in better teeth arrangement.
Should never be placed at convex lingual surface of tooth.
JOINING INDIRECT RETAINER TO MAJOR CONNECTORMain function of this minor connector is to provide indirect retention and support to the denture
Arise at right angles from major connector with rounded junction
Designed to fit the embrasure space so that they are not visible
Proximal plate: surface of minor connector contacting the tooth.Guiding plane: surface of tooth in contact with proximal plate.
Undercuts along proximal surfaces of teeth should be removed.
Area where minor connector is to be designed should be devoid of undercuts. Should have a clear straight parallel path of insertion
JOINING DENTURE BASE WITH MAJOR CONNECTORIt should fulfil following requirements:
Rigid enough to support and resist breakage of denture base
Allow proper arrangement of natural teeth
Maxillary distal extension cases: minor connector should extend up to the maxillary tuberosity
Mandibular distal extension cases: minor connector should cover 2/3rd the length of edentulous ridge
Available in three forms:Lattice-work constructionMesh-work constructionBead, wire, or nail head minor connectors
LATTICE-WORK CONSTRUCTION2 struts of metal (16 gauge).
In mandible: one strut buccal, other strut lingual
In maxilla: one strut buccal, other strut border of major connector
Smaller struts running over crest of ridge transversely connecting the two major struts forming a lattice-work
Longitudinal struts avoided as they interfere with arrangement of artificial teeth
Relief given between struts and ridge for acrylic to flow. Done with help of tissue stops
Used for multiple teeth replacements
MESH-WORK CONSTRUCTIONThin sheet of metal with multiple small holes that extends over crest of residual ridge to buccal, lingual, and posterior limits.
Used for replacement of multiple teeth.
Additional pressure required for acrylic resin to flow in to the holes. (disadvantage)
Retention to denture base is less as holes are smaller and attachment of acrylic is weaker.
BEAD, WIRE, OR NAIL HEAD MINOR CONNECTORSMinor connector directly lines edentulous ridge without any relief.
Acrylic denture base attached to outer surface of minor connector and retention obtained by projections of metal on superior surface. Projections may be beads, nails, or pointing wires.
This minor connector is indicated for tooth-supported dentures with well-healed ridges where frequent relining and rebasing is not anticipated.
Advantagesbetter soft tissue response to metal than acrylic
DisadvantagesRelining is difficultWeakest attachment
TISSUE STOPSIntegral part of lattice or mesh-work type minor connectors where tissue stops are used to stabilize the framework during packing of resin
Prevents distortion of framework.
Stop gives adequate space for acrylic to flow in-between framework and tissue surface of cast
Stops are prepared by removing 2 sq. mm of relief wax used to create space beneath lattice or mesh work from point where posterior end of minor connector crosses centre of the ridge.
During waxing, this little depression is waxed as a projection of lattice or mesh work
After casting, this projection contacts the edentulous ridge of the cast and prevents framework from being distorted during acrylic packing
FINISH LINESFinish line in partial denture denotes junction between acrylic denture base and major connector or any polished metal surface.
Internal finish line:Space between metal framework and tissue surface of cast is provided by adding relief wax onto edentulous ridge on master cast. Ledge created by margin of relief wax in metal framework should be sharp and definite.This margin is called internal finish line.
External finish lineJunction between acrylic and exposed metal on the external or polished surface. Must be less than 90 at junction of major and minor connector whereas junction between approach arm and denture base connector should be a butt joint.
APPROACH ARM MINOR CONNECTOR FOR BAR TYPE CLASPThis minor connector almost acts like a clasp
Helps to position retentive tips of gingivally approaching clasps.
It is not rigid as it does not have to bear any load. Should have limited flexibility to aid in removal. Retention is improved by its springy action
Supports direct retainer which engages undercut of tooth by approaching it gingivally.
Since this minor connector lies below height of contour of tooth, it should be made slightly flexible for easy insertion and removal. Partial cut on root of minor connector makes it flexible.
Cannot be used over soft tissue undercuts.