Overdentures are dentures which derive their support from one or abutment teeth by completely enveloping them beneath the fitting surface. The abutment teeth are usually root filled and either simply reduced or used in conjunction with stud or bar precision attachments. For both of these situations two techniques of impression taking are used. When the teeth are already root filled and will later be reduced it is termed an immediate overdenture. An impression of the root filled teeth, prior to reduction, is taken in alginate or elastomer in a special tray. The impression is cast and the abutment teeth on the model are reduced in height by 4mm and the dentures are constructed around this. When the processed denture is fitted, it is relined with cold cured acrylic in the areas around the abutment teeth to make it fit as well as possible. Overdentures can also be implant supported

Dentures with attachment (Snap in Dentures) :

Snap-in dentures are the most effective choice when it comes to stability. They are held securely in place with the help of dental implants or anchors onto the existing teeth. What makes them unique is the locator attachments embedded within the tissue side of the denture. The locator attachments snap onto the implants or onto the locator receptors. This means they are convenient and removable (like partial dentures). Snap-in dentures are usually used when a patient doesn't have any teeth, but still enough bone to support an implant.