When a denture is first constructed, it is of course a perfect fit, as the impression it is taken from is usually fairly recent.
However, the mouth is fluid, and after tooth loss the underlying bone mass, can change shape for quite a few years after the teeth are extracted.
This bone reduction is quite marked just after the loss of teeth, and if a denture has been constructed by the clinician before extraction (an immediate denture) the initial bone loss necessitates a replacement of the fitting surface of the denture to take up the slack as it were.
This is the most likely reason to reline a denture, and at this stage a new denture may also be contemplated.
Where a reline is not such a good idea, is when the denture itself is fairly old, and all dentures are fairly old if they are between 5-7 years, but they appear loose.
In this case a thorough inspection of the chewing surfaces of the teeth themselves should be made and it should be ascertained by the clinician whether a new set dentures might be the best option.
Relines are normally only carried out on full dentures, whilst partial dentate plates, if properly constructed from metal are not suitable for relining in plastic.
Partial plastic plates are notoriously difficult to reline and fit, so are also best avoided.
You may also have heard of the phrase Soft Reline and wondered what it was. A soft reline is usually constructed on a full lower denture and consists of a rubber like coating placed by a dental technician on the fitting side of the denture to absorb some of the impact of mastication on a fragile lower jaw. These can be added to an existing denture or be manufactured from new.
Most modern soft lining materials should be replaced within a 2 year time period
Source by Luis Fairman