Dentures over implants
Although less frequently required, given upper dentures generally have adequate retention, the motivation is that dentures can be fabricated without the palate being covered.
Without the benefit of artificial anchors, upper dentures are held in place by suction. In order for this suction to be successful the entire palate must be covered right back to the region called the post dam. If you were to place your tongue up to the roof of your mouth and then slowly roll the tip back you will get to a point where the firm palate meets the soft tissue. It is at this junction the posterior edge of the denture must terminate with a raised bead pressing into the soft tissue and creating a seal. This bead or seal is referred to as the post dam.
For most patients the post dam creates no problems but occasionally we find patients who are very sensitive and have an acute gag reflex, making this depth of coverage very uncomfortable, and in a worse case intolerable. In the past, patients would simply have to suffer this unfortunate condition often placing dentures in for only brief periods. Fortunately implant technologies are now providing alternatives in how dentures are retained and designed.
With the placement of implants in an upper ridge, conventional suction is no longer required which means dentures can be fabricated without need for palatal suction. This leaves the tongue free to lay against the natural tissues and eliminates the portions of the denture that are most commonly responsible for gagging problems.
There are however some considerations to be made before taking on this type of treatment. The alveolar bone that makes up the upper ridge is less dense than that of the lower arch, resulting in a greater number of implants being required to achieve a solid stable placement. Often four or six implants will be used and will be united by a specialized bar. This bar provides added strength to the implants by binding then into group function and also acts as a frame for the denture to clip onto. Given the increased level of treatment required to complete the program it is often more costly