- Swing-lock RPDs are used, when a number of remaining teeth is too few to support a conventional design.
- This denture has a labial bar extending labially all along the arch like a major connector.
- The labial bar is connected to the remaining parts of the denture by a hinge on one side and a lock on the other.
- The labial bar can be unlocked during insertion and locked after insertion.
- Indications
- Missing key abutments
- When the number of remaining natural teeth is less
- When the remaining teeth are too mobile to serve as abutments
- When the soft tissue and the tooth are in unfavorable contours
- Provide retention and stability for maxillofacial prostheses, such as obturators
- For retention of the prosthesis in case of loss of large segments of teeth and alveolar ridge, due to trauma or infection.
- CONTRAINDICATIONS
- When the vestibule is shallow
- High labial frenal attachment
- Patient with poor oral hygiene
- Advantages
- The construction is relatively simple and inexpensive.
- Disadvantages
- It is unaesthetic in patients with short lips.
- Tipping is seen in the remaining anterior teeth in the distal extension case.
Fabrication
- Selection of metal for swing-lock framework
- The metal of choice is chrome alloy.
- Gold alloys wear off due to constant movement
- Surveying and designing
- The cast is mounted on the surveyor.
- The path of insertion is from a lingual direction with the labial arm open.
- Lingual plate
- The lingual plate should be designed to end above the survey line.
- It prevents the tissueward displacement.
- Occlusal rest
- helps to prevent tissueward displacement of the denture.
- Major connector
- The mandibular major connector extends above the survey line with scallops extending up to contact points.
- The maxillary major connector is the complete palatal or closed horseshoe with borders extending up to or above the survey line.
- Labial arm design
- The vertical projection of the labial bar should be designed to touch the teeth below the height of contour.
- Conventional design
- This consists of a labial bar with metallic vertical I-bar or T-bars attached to it.
- Using acrylic resin retention loop
- This is indicated for patients with short lips and where aesthetics is of concern.
- Selection of impression material = Heavy-bodied alginate is best preferred.
- Tray selection = A custom tray should be used for recording maximum labial and buccal vestibular depths.
- For the secondary impression, 5–6 mm space should be given between the teeth and the tray when placed in the mouth.
- Making the impression.
- It is similar to conventional dentures.
- Dual impressions may be required for distal extension.
- Framework fabrication.
- Fitting the framework.
- Arranging artificial teeth to occlusion
- Insertion = Lingual path of insertion is done.
- Post insertional care = Oral hygiene should be maintained by the patient. Distal extension RPD has to be frequently relined.