Swing lock partial denture/ dentistry dental implants


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Swing lock partial denture/ dentistry dental implants

  1. 1. SWING LOCK PARTIAL DENTURE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Introduction This denture was first described and documented by Simmon’s in 1963. The concept was recommended for maximizing stability and retention by gaining access to many more teeth surfaces with the unique clasping mechanisms offered by incorporation of the lock, hinge and gate assembly, allowing all teeth to become primary abutments. This denture has a labial bar in addition to the lingual major connector. The labial bar extends labially all along the arch and is attached to the remaining parts of the denture by a www.indiandentalacademy.com
  3. 3. Indications There are a number of indications for use of the swing-lock design in the treatment of partially edentulous patients • Too few remaining natural teeth for a removable partial denture of conventional design. • Remaining teeth too mobile to serve as abutment teeth for conventional design. • Position of remaining teeth not favorable for a conventional design. • Retention and stabilization needed for maxillofacial prostheses such as obturators for post surgical patients. • To retain prosthesis for patients who have lost large segments of teeth and alveolar ridge through traumatic injury. www.indiandentalacademy.com
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  5. 5. Contraindications Shallow vestibule Depth of labial vestibule should be 6 to 8 mm to accommodate the labial bar. A zone of attached gingiva between 2 and 4 mm apical to the gingival sulcus is advisable for a favourable long term prognosis. A shallow vestibule can be surgically modified with a vestibular extension and a free gingival graft. The lack of attached gingiva can be corrected with a free gingival graft or an apically repositioned flap procedure. Extended frenum A frenum that extends to a shallow zone of attached gingiva has the potential of future irritation by the labial bar. An. extended frenum should be removed surgically and a free gingival graft placed at the site of the frenum. www.indiandentalacademy.com
  6. 6. Esthetic requirements Some patients have a prominent lip line, thus, showing gingiva at the necks of the teeth when smiling or speaking. In these situations, the occasional display of metal may be unacceptable to the patient. Some authors have suggested that a veneer of acrylic resin be processed to the labial bar of the swing lock to improve the esthetics. Poor plaque control Regardless of the type of removable partial denture placed, retention of plaque may become a problem. This is especially true for a swing lock removable partial denture, since a great deal of tooth surface is contacted by partial denture. Thus... patients with poor hygiene maintenance are poor candidates for a swing lock removable partial denture. www.indiandentalacademy.com
  7. 7. Advantages The primary advantage of the swing-lock concept of treatment is that it provides a relatively inexpensive method of using all or most of the remaining teeth for the retention and stabilization of a prosthesis. Alternatives to this type of treatment include: 1. Removal of the remaining teeth and 2. Fixed splinting of the remaining teeth and con-struction of a conventional removable partial denture. The latter is relatively time consuming and expensive and presents problems if one of the splinted teeth fails. Loss of a splinted tooth could necessitate removal and reconstruction of a fixed splint, whereas a tooth can be removed and added to the major connector of swing-lock prosthesis through a simple laboratory pro-cedure. Because the construction of a swing-lock remov-able partial denture is relatively simple and inexpen-sive, it can be used in situations for which more con-ventional types of treatment may appear hopeless.www.indiandentalacademy.com
  8. 8. Disadvantages • A swing-lock prosthesis can produce a relatively poor esthetic result for patients with short or extremely mobile lips. • Obtaining perfect adaptation of a resin veneer is difficult because the path of insertion is dictated by the hinge movement of the labial bar. • The remaining teeth are grasped firmly by the prosthesis. • A long distal extension base is likely to move toward the tissue under the forces of occlusion. This movement can tip the teeth grasped by the prosthesis. www.indiandentalacademy.com
  9. 9. TREATMENT PLANNING When the swing lock removable partial denture is considered the position of the lips during smiling is recorded and transferred to the primary diagnostic casts. A facial sulcus depth of 6 to 8 mm is recommended for placement of the retentive gate element. A high frenal attachment and / or shallow sulcus requires surgical correction prior to making a working impression. Periodontal health is a prerequisite to therapy unless the prosthesis is considered an interim measure for the informed patient or is used as a provisional/ definitive prosthesis as periodontal therapy is provided. www.indiandentalacademy.com
  10. 10. The diagnostic cast is surveyed to plan further tooth preparation, including guide planes and rest seat and to establish clasp placement. The desired tooth modifications may be achieved by reshaping the teeth, or when castings are indicated by incorporating the desired contours, into the restorations. Following mouth preparation a working impression is made. Irreversible hydrocolloid in a selected rimlock tray has often proved adequate .Mobile teeth indicate the use of reversible hydrocolloid to avoid any tooth displacement. www.indiandentalacademy.com
  11. 11. Conventional laboratory procedures are followed. The cast is poured with a compatible vacuum mixed dental stone. A wax occlusal rim with an acrylic resin base can be fabricated on the working cast, a facebow transfer and occlusal registration record are obtained, and casts are mounted on a semiadjustable articulator. The tooth mold and lock are established according to the patient's preference to use a finger/ thumb of the left or right hand. www.indiandentalacademy.com
  12. 12. Fabrication of a swing lock partial denture It includes the following steps : • Selection of Metal for Swing-lock Framework • Surveying and Design • Selection of Impression Material • Tray selection • Making the Impression • framework fabrication • fitting the framework • jaw relations • occlusal development • insertion • post insertion care www.indiandentalacademy.com
  13. 13. Selection of Metal Chrome alloy is chosen instead of gold alloy. This is because gold alloy shows wear (due to constant movement of the hinge) after a short time of use. If gold alloy is to be used a greater deal of metal has to be incorporated into the framework to increase rigidity and strength. Surveying and Design The cast is mounted on a surveyor with the occlusal plane parallel to the base and surveyed . The path of insertion is from a lingual direction with the labial arm open.. www.indiandentalacademy.com
  14. 14. Design considerations to be followed for each part of the denture : Lingual plate: It should be designed to end above the survey line and hence it prevents the tissue ward displacement of the denture. Occlusal rest : The occlusal rests also help to prevent tissue ward displacement of the denture. Major connector: The mandibular major connector of choice is a lingual plate. It extends above the survey line with scallops extending up to contact points. The maxillary major connector of choice is a complete palate or a closed horseshoe with borders extending up to or above the survey line. www.indiandentalacademy.com
  15. 15. Labial arm design :The vertical projections of the labial bar should be designed to touch the teeth below the height of contour. Hence, they prevent occlusal movement. The design of the labial arm can be of two types: Conventional design: It consists of a labial bar with metallic vertical I- bar or T-bars attached to it. They contact the teeth below the survey line. Using acrylic resin retention loops: It is indicated for patients with short or hypermobile lips and where aesthetics is of concern. The acrylic loops are translucent or tooth colored hence, they are more aesthetic. Rests are placed on teeth adjacent to the edentulous ridge. Placement of hinge is determined by the patient comfort. www.indiandentalacademy.com
  16. 16. Selection of Impression Material : Alginate is the impression material of choice. Large gingival embrasures and gingival recession will usually be present in these cases, the impression material should tear in the interproximal areas during removal. This will allow easy removal of the impression without any damage to the teeth. This is not possible in rubber base impression materials. Heavy bodied Alginate is preferred. www.indiandentalacademy.com
  17. 17. Making the Impression. Impression procedure for swing lock dentures is similar to conventional dentures. Dual impressions may be required for distal extension cases. Framework Fabrication A master cast is poured from the secondary impression. The master cast is waxed and undercuts are blocked out before duplication. The master cast is duplicated to form the refractory cast. The design of the denture is transferred to the refractory cast. After design transfer, the wax pattern is fabricated on the refractory cast . The refractory cast is invested, wax is burned out and casting is done. The resultant framework is trimmed, finished and polished. www.indiandentalacademy.com
  18. 18. Tray Selection: A custom tray is essential for recording maximum labial and buccal vestibular depths. Secondary impression procedures should be carried out. About 5 to 6 mm spacing should be present between the teeth and the tray when placed in the mouth. Holes should be made in the tray to help retain the alginate. www.indiandentalacademy.com
  19. 19. Fitting the Framework. A framework is tried in the patient before arranging the artificial teeth. The procedure is similar to that done for conventional removable partial dentures except that the fit of the labial bar and the rest of the framework are checked separately. Jaw Relations After framework try-in, a temporary denture base is fabricated using the framework. Occlusal rims are fabricated over the temporary denture base.The framework with the temporary denture base and occlusal rim is inserted into the patient's mouth and all the three jaw relations are recorded After jaw relation, the casts with the jaw relation records are mounted in an articulator. www.indiandentalacademy.com
  20. 20. Arranging Artificial Teeth to Occlusion Occlusion should be such that no lateral forces act on the prosthesis during occlusion. Simultaneous contact between natural and artificial teeth should be present. These factors are checked during denture try in. After arranging the artificial teeth, the modelling wax that is to form the denture base is contoured and polished . Consecutively the trial denture is flasked and acrylized as usual. www.indiandentalacademy.com
  21. 21. Insertion A lingual path of insertion is used. Pressure indicator paste is used to detect pressure areas. Occlusion is evaluated in centric and eccentric relations. In case of distal extension RPD, the vertical projections should be bent away from the teeth so that the anterior teeth are not tipped lingually by the labial bar under occlusal load. Post-insertion Care Oral hygiene measures must be emphasized. Distal extension RPD has to be frequently relined. Loosened lock mechanisms should be tightened. Teeth can be added to the frame work at later stages after the removal of any tooth .www.indiandentalacademy.com
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