The pink portion of your denture (known as its base) rests on the gum tissue left where you have lost one or more of your teeth, whether you wear a partial denture or a full one. This gum tissue is called the edentulous ridge. It is very important to the function and comfort of your denture for that part of the base that contacts this ridge (called its tissue surface) to do so very securely. If it does not, your denture will not fit your mouth as well as it could, causing instability and irritation. This instability can negatively effect speech and/or retention as your denture rocks on your ridge or actually dislodges. This irritation, in the form of sores, can result from the movement of a loose denture on your ridge and/or trapping of food particles against your ridge underneath the denture due to a less than precise fit.
The reason for this sloppiness is the changing nature of your gum tissue. Immediately after tooth loss, your edentulous ridge begins to shrink because it no longer supports the roots of any teeth that you have lost. The vast majority (over 90%) of this shrinkage normally occurs over the first three months or so after tooth loss and its physical dimensions usually depend on the cause of your tooth loss. In other words, if you lose teeth because of the bone loss associated with periodontal disease, there will be more contraction overall of your edentulous ridge than if you lost those same teeth because of unrestorable decay with no periodontal disease. Regardless of the cause or degree of reduction, upwards of 90% of it will occur in those first three to four months after your tooth loss. The rest of the decrease in your ridge occurs very gradually over the rest of your life. This residual decline can be minimized by always sleeping with your dentures out and by having your dentures relined whenever instability becomes noticeable.
Relining your denture is a relatively simple process whereby additional base material is adapted to the tissue surface of your denture so it will more accurately correspond to the changed form of your edentulous ridge. This is done by using your existing denture as a tray with which to take an impression of your ridges in their current contours. The impression so taken is poured in stone to produce a model that correctly represents the present state of your ridge. Base material is then added to the tissue surface of your denture as a paste and your denture is then compressed onto the model. The difference between the current state of your ridge as established by the model and its previous shape as reflected in the tissue surface of the denture base is filled by the added base material. Any extra material extrudes past the edges of the base as your denture is compressed onto the model and then your denture is processed under heat in a pressure cooker to harden the paste. Any extruded base material is trimmed after processing and then the base is smoothed and polished. Your denture, so relined, is now ready for use with a more comfortable and stable fit.
Reline material is injected onto the tissue surface of this full lower denture as it is
pressed down onto the model of its owner's lower ridge.
Immediate dentures (those inserted directly after your teeth have been extracted) are customarily relined three to four months after they are placed. This in keeping with the fact that the vast majority of decrease in ridge size normally occurs over the first three months or so after tooth loss. The gradual rate of remaining decline that occurs over the rest of your life typically necessitates further relines about every five years. Certain diseases (including diabetes and osteoporosis) that contribute to bone loss may accelerate this schedule. If you have any questions about this process, please ask Dr. McArdle.