minor connectors & rests & rest seats / orthodontic courses by indian dental academy

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  • MINOR CONNECTORSRESTS & REST SEATS

    INDIAN DENTAL ACADEMY

    Leader in continuing dental education www.indiandentalacademy.comwww.indiandentalacademy.com

    www.indiandentalacademy.com

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  • MINOR CONNECTORSCONTENTS:Definition Functions of minor connectorsBasic principles of design of a minor connectorTypes of minor connectorsTissue stops and finish lines

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  • Definition: Minor connectors can be defined as the connecting link between the major connector or base of a removable partial denture to other units of a prosthesis such as clasp assembly,indirect retainers,rests etc G.P.T-8. www.indiandentalacademy.com

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  • FUNCTIONS OF A MINOR CONNECTOR1.To transfer functional stress to the abutment teeth. Prosthesis- to- abutment function

    2.To transfer the effect of retainers, rests and stabilizing components to the rest of the denture. Abutment - to - prosthesis function www.indiandentalacademy.com

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  • Basic principles of design of a minor connector1. Should be rigid2. Should have triangular cross section with thickest portion near the lingual line angle and the thinnest portion near the buccal line angle of the tooth.3. Should be broader buccolingually and thinner mesiodistally.4. Should form a right angle with the major connector so that the gingival crossing is abrupt and cover as little gingival tissue as possible. 5. Sharp angles should be avoided and spaces should not exist for trapping of food debris.6.Should never be placed on the convex lingual surfaces of the tooth where its bulk will be evident.www.indiandentalacademy.com

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  • Types of minor connectors1. Join clasp assembly to the major connector.2. Join indirect retainers and auxilary rests to major connector.3. Join denture base to the major connector4. Serve as an approach arm for a vertical projection or bar type of claspwww.indiandentalacademy.com

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  • 1.Minor connectors joining clasp assembly to major connector- Rigidwww.indiandentalacademy.com

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  • Minor connectors contacting the guide plane surfaces are as broad as 2/3 the distance between the tips of adjacent buccal and lingual cusps of the abutment tooth. They should extend gingivally contacting an area of the abutment tooth from the marginal ridge to 2/3 the length of the enamel crown.

    If no clasp arm is formed as when a bar clasp originates elsewhere, the connector should be tapered to a knife edge the full length of the buccal surface.

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  • When an artificial tooth is to be placed the thickest portion should be at the lingual line angle of the abutment tooth.This way bulk is ensured with least interference to the placement of the artificial tooth.

    If the clasp assembly is not being placed on a tooth adjacent to the edentulous space, the minor connector must be positioned in the embrasure between two teeth.

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  • 2. Minor connectors that join indirect retainers or auxiliary rests to major connector - Should form a right angle with the major connector - Should lie in embrasure between teeth to disguise its bulk as much as possible.www.indiandentalacademy.com

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  • 3.Minor connectors that join the denture base to the major connectorIt should be rigid enough to support and resist breakage of the denture base.In maxillary distal extension cases it should extend up to the maxillary tuberosity.In mandibular distal extension case the minor connector should cover 2/3 the length of edentulous ridge. 3 types:1. Lattice work construction2. Mesh construction3. Bead,wire or nail head minor connectorwww.indiandentalacademy.com

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  • 1.Open latticework constructionConsists of longitudinal and transverse struts that form a ladder like network

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  • In the mandibular arch, one longitudinal strut should be positioned buccal to the crest of the ridge and one should be positioned lingual to the crest of the ridge.In the maxillary arch, one longitudinal strut should be positioned buccal to the crest of the ridge and the border of the maxillary major connector will act as the second longitudinal strut.Transverse struts should be placed such that they do not interfere with tooth placement. relief should be given between struts and the ridge for acrylic to flow. This is done with the help of tissue stops.Relief provides space between minor connector and tissues of the residual ridge.the space permits an acrylic resin to encircle longitudinal and transverse struts.

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  • AdvantagesProvides the strongest attachment of the acrylic resin denture base to the removable partial denture.

    Easiest to reline if necessary because of ridge resorption.

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  • 2.Mesh construction Rigid metal screen with channels that pass through the connector which are intended to permit acrylic resin penetration,which allows resin encirclement of the minor connector and mechanical retention of denture base.www.indiandentalacademy.com

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  • Main drawback is that it is more difficult to pack acrylic resin dough because more pressure is needed against the resin to force it through the small holes. It also does not provide as strong an attachment for the acrylic denture base as compared to the lattice framework

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  • 3.Bead ,wire or nail head retention minor connector- Used with a metal denture base which is cast to fit directly against the edentulous ridge. Hence no relief is provided beneath this minor connectors.www.indiandentalacademy.com

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  • Retention of the acrylic resin is obtained by projection of metal on its surface These projections may be in the form of beads,wires or nail heads.

    Advantages:Most hygienicThermal stimulation

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  • Disadvantages: -Difficulty to adjust the metal base. -Cannot be adequately relined in case of ridge resorption. -Weakest attachment.www.indiandentalacademy.com

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  • Tissue stopsUsed on all distal extension partial dentures using latticework or mesh retention.

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  • FINISH LINESThe term finish line in a partial denture denotes the junction between the acrylic denture base and major connector or any polished metal surface.To provide sufficient bulk of acrylic resin to produce a smooth and even joint with the metal framework, provision must be made to provide space for a butt joint so that the acrylic resin can be finished evenly with the major connector.

    2 types - Internal finish line - External finish linewww.indiandentalacademy.com

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  • Resin-metal interfaces must be created on both internal and external surfaces of associated major connectors.In case of metal base minor connectors, acrylic resin is processed only on the external surface. Therefore resin-metal interfaces should be created only on external surfaces.These resin-metal interfaces are referred to as finish lines and if they are located on the outer surface of the major connector, they are called external finish lines and if they are positioned on the inner or tissue surfaces they are termed as internal finish lines

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  • Internal finish line

    External finish line

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  • Internal finish lines : They are formed as a result of relief wax placed on the edentulous ridge prior to duplication. The relief wax creates an elevated area on the resultant refractory cast. The margins of the relief wax establish internal finish lines in the completed metal frame work. Margins should be sharp and well defined.

    External finish lines: This also must be sharp and should be slightly undercut to help lock the acrylic resin to the major connector.the internal angle formed at the junction of major and minor connector should be less than 90 degrees. An external finish line is formed by the placement and carving of the wax during framework fabrication.the contours of external finish line should be consistent with the contours of major connector.

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  • 4. Minor connectors that serve as an approach arm for vertical projection or bar type of clasp The only minor connectors that are not required to be rigid.these components supports direct retainers and therefore must exhibit some degree of flexibility.a minor connector of this type approaches the tooth from an apical direction rather than from an occlusal directionwww.indiandentalacademy.com

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  • RESTS AND REST SEATSwww.indiandentalacademy.com

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  • RESTS & REST SEATSCONTENTS :INTRODUCTIONHISTORICAL REVIEWTYPES / CLASSIFICATIONFUNCTIONSREQUIREME

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