CONNECTORS –in FPD

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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com CONNECTORS in FPD www.indiandentalacademy.com

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Connectors are those parts of a fixed partial denture or splint that join the individual Retainers and Pontics together. Usually this is accomplished with -"Rigid connectors” although nonrigid connectors are used occasionally. The latter are usually indicated when it is impossible to prepare a common path of insertion for the abutment preparations for an FPD www.indiandentalacademy.com

defn:

defn CONNECTOR The portion of an FPD that unites the retainer(s) and pontic(s). RIGID CONNECTOR A cast, soldered, or fused union between the retainer(s) and pontic(s). NON RIGID CONNECTOR Any connector that permits limited movement between otherwise independent members of an FPD. www.indiandentalacademy.com

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RIGID CONNECTORS:

RIGID CONNECTORS Rigid connections in metal can be made by casting, soldering, or welding. Cast connectors are shaped in wax as part of a multiunit wax pattern. Cast connectors are convenient and minimize the number of steps involved in the laboratory fabrication. www.indiandentalacademy.com

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The fit of the individual retainers may be adversely affected because distortion more easily results when a multiunit wax pattern is removed from the die system. www.indiandentalacademy.com

Soldered connectors:

Soldered connectors involve the use of an intermediate metal alloy whose melting temperature is lower than that of the parent metal The parts being joined are not melted during soldering but must be thoroughly wettable by liquefied solder. www.indiandentalacademy.com

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Dirt or surface oxides on the connector surfaces can reduce wetting and impede successful soldering; for example, the solder may melt but will not flow into the soldering gap. www.indiandentalacademy.com

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Welding :

Welding is another method of rigidly joining metal parts. Here the connection is created by melting adjacent surfaces with heat or pressure. A filler metal whose melting temperature is about the same as that of the parent metal can be used during welding. www.indiandentalacademy.com

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In industrial metalworking, a distinction is made between soldering, in which the filler metal has a melting point below 450 º C (842 º F), and brazing, in which the filler has a melting point above 450 º C Rigid connections in dentistry are generally fabricated above 450 º C, but the process has almost always been referred to in the dental literature as soldering. A proposed international standard uses the term brazing. www.indiandentalacademy.com

NONRIGID CONNECTORS:

NONRIGID CONNECTORS Nonrigid connectors are indicated when it is not possible to prepare two abutments for an FPD with a common path of placement. Segmenting the design of large, complex FPDs into shorter components that are easier to replace or repair individually is advisable. This can be helpful if there is uncertainty about an abutment's prognosis. If the abutment fails, only a portion of the FPD may need to be remade. www.indiandentalacademy.com

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In the mandibular arch, nonrigid connectors are indicated when a complex FPD consists of anterior and posterior segments. During the mandibular opening and closing stroke, the mandible flexes mediolaterally.' Rigid fixed partial dentures have been shown to inhibit mandibular flexure, and extensive splints have been shown to flex during forced opening The associated stresses can cause dislodgment of complex FPDs. Segmenting complex mandibular FPDs can minimize this risk. www.indiandentalacademy.com

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Nonrigid connectors are generated through incorporation of prefabricated inserts in the wax pattern or through custom milling procedures after the first casting has been obtained. The second part is then custom-fitted to the milled retainer and cast. They are often made with prefabricated plastic patterns. The retainers are then cast separately and fitted to each other in metal. www.indiandentalacademy.com

CONNECTOR DESIGN:

CONNECTOR DESIGN The size, shape, and position of connectors all influence the success of the prosthesis. Connectors must be sufficiently large to prevent distortion or fracture during function but not too large; otherwise, they will interfere with effective plaque control and contribute to periodontal breakdown over time. www.indiandentalacademy.com

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Adequate access (i.e., embrasure space) must be available for oral hygiene aids cervical to the connector If a connector is too large incisocervically, hygiene is impeded and over time periodontal failure will occur For esthetic FPDs, a large connector or inappropriate shaping of the individual retainers may result in display of the metal connector. www.indiandentalacademy.com

TYPES OF CONNECTORS:

TYPES OF CONNECTORS RIGID CONNECTORS Rigid connectors must be shaped and incorporated into the wax pattern after the individual retainers and pontics have been completed to final contour but before reflowing of the margins for investing www.indiandentalacademy.com

Cast Connectors:

Cast Connectors Connectors to be cast are also waxed on the master cast before reflowing and investing of the pattern. The presence of a cast connector makes the pattern somewhat more awkward. Access to the proximal margin is impeded, and the pattern cannot be held proximally during removal from the die. www.indiandentalacademy.com

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Restricting cast connectors to complete coverage restorations is therefore advisable, which can be gripped buccolingually. Partial-coverage wax patterns are easily distorted when they are part of a single-cast FPD. www.indiandentalacademy.com

Soldered Connectors. :

Soldered Connectors . As with cast connectors, connectors to be soldered are waxed to final shape but are then sectioned with a thin ribbon saw therefore, when the components are cast, the surfaces to be joined will be flat, parallel, and a controlled distance apart. This allows accurate soldering with a minimum of distortion. www.indiandentalacademy.com

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Molten solder will flow toward the location where the temperature is highest. In metal, the two flat surfaces previously created in wax retain heat, ensuring that the highest temperature is in the connector area. www.indiandentalacademy.com

Soldering Gap Width. :

Soldering Gap Width. As gap width increases, soldering accuracy decreases . Extremely small gap widths can prevent proper solder flow and lead to an incomplete or weak joint. www.indiandentalacademy.com

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An even soldering gap of about 0.25 mm is recommended. If a connector area has an uneven soldering gap width, obtaining a connector of adequate cross-sectional dimension without resulting distortion is more difficult www.indiandentalacademy.com

Loop Connectors :

Loop Connectors Although they are rarely used, loop connectors are sometimes required when an existing diastema is to be maintained in a planned fixed prosthesis. The connector consists of a loop on the lingual aspect of the prosthesis that connects adjacent retainers and/or pontics. www.indiandentalacademy.com

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The loop may be cast from sprue wax that is circular in cross section or shaped from a platinum-goldpalladium (Pt-Au-Pd) alloy wire. Meticulous design is important so that plaque control will not be impeded www.indiandentalacademy.com

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NON RIGID CONNECTORS:

NON RIGID CONNECTORS The design of nonrigid connectors that are incorporated in the wax pattern stage consists of a mortise (also referred to as the female component) prepared within the contours of the retainer and a tenon (male) attached to the pontic www.indiandentalacademy.com

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The mortise is usually placed on the distal aspect of the anterior retainer. Accurate alignment of the dovetail or cylindrically shaped mortise is critical; it must parallel the path of withdrawal of the distal retainer www.indiandentalacademy.com

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Paralleling is normally accomplished with a dental surveyor. When aligning the cast, the path of placement of the retainer that will be contiguous with the tenon is identified. www.indiandentalacademy.com

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The mortise in the other retainer is then shaped so its path of insertion permits concurrent seating of the tenon and its corresponding retainer. The mortise can be prepared freehand in the wax pattern or with a precision milling machine. www.indiandentalacademy.com

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Another approach is to use prefabricated plastic components for the mortise and tenon of a nonrigid connector www.indiandentalacademy.com

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As an alternative, a special mandrel can be embedded in the wax pattern and the abutment retainer can be cast, with refinement of the female component as necessary; the male key is then fabricated of autopolymerizing acrylic resin and attached to the pontic. www.indiandentalacademy.com

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Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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