Following the extraction of teeth, the surrounding bone begins a dynamic process of shrinkage and remodeling. Initially, in the first few months, the gum shrinkage is quite rapid and a denture will become loose fairly quickly. The type of reline done during this healing period is only a temporary one. The bone will continue to shrink after this initial period but at a slower rate for up to approximately 12 months after the extractions. Unfortunately, the shrinkage of gums doesn't stop there. The bone will continue to resorb year after year which will affect the fit of a denture at some point if it is not relined and may adversely affect the gums. 

Many of our patients, in response to our explanation, ask questions like "Why does my old upper denture still have suction if my gums are always shrinking?". The reason for this is that the upper and lower gums shrink at different rates. It has been observed that the lower gums can shrink four times faster than the upper. It is quite common for upper denture wearers to wear the back teeth down significantly over many years of use while still preserving decent suction. This is why we don't recommend a fixed schedule for relining upper dentures. The best approach is to visit your dental practitioner annually for a check up to help assess your fit.

Properly maintaining full lower dentures, on the other hand, requires that they be professionally relined every three years to keep up with the changes in the gums. Since full lower dentures don't typically have a suction fit, the improvement in that fit after relining the lower denture is often subtle but it is important not to overlook this necessary procedure.