Denture rebases.
A rebase replaces the whole acrylic base, keeping the existing teeth and their arrangement. Where the arrangement is good and the base is not, it is the middle option between a reline and a remake. Tick Rebase under Procedure.
Reline, rebase or remake
A reline adds new material to the fitting surface, keeping the existing base. A rebase replaces the base entirely while retaining the teeth in their current positions. A remake starts again with new records.
The decision follows from what is actually wrong. Loss of fit alone: reline. Loss of fit plus a base that is discoloured, porous, warped, repeatedly repaired or thin: rebase. Anything wrong with the tooth arrangement, vertical dimension, occlusion or appearance: remake.
Rebasing a denture whose teeth are badly worn or badly positioned preserves the problem in a new base.
When rebasing is the right call
A denture whose tooth arrangement and appearance the patient is happy with, where the base has deteriorated — accumulated repairs, staining that will not clean, porosity, or a base thinned by successive relines.
Also where multiple relines have built up layers of material of varying age and quality, which is common in a long-serving prosthesis and produces a base that is neither strong nor hygienic.
The advantage over a remake is that the patient keeps a prosthesis they have adapted to, with tooth positions they have accepted.
Records
As for a reline, the denture is the tray: relieve the fitting surface, remove undercuts, border mould, and take the impression with the denture correctly seated and the occlusion closed in the right relationship.
Send the opposing arch or the opposing denture. The occlusion is being re-established against it as the base is replaced.
Where the vertical dimension is being altered at the same time, that has to be recorded and stated — it is not something the laboratory should infer.
What the patient should expect
The denture will be away for processing, so plan for that and tell the patient in advance. Where they cannot be without it, a temporary alternative or a chairside interim may be needed.
The rebased denture will feel different, because the fit has changed and the base thickness may differ. A short adaptation period is normal.
Where the teeth are showing wear that is not yet bad enough to warrant a remake, say so at the same time — the patient should know the prosthesis has a finite remaining life rather than assuming the rebase has reset it.
What is preserved and what is not
A rebase keeps the teeth and their positions relative to one another. It does not necessarily keep their position relative to the ridge, because the new base is being formed against a ridge that has changed.
That is usually the point — the prosthesis is being brought back into adaptation. But where resorption has been substantial, the tooth positions that suited the original ridge may no longer suit the current one, and lip support or occlusal plane may need reconsidering.
Where that is the case, a remake with new records is the more honest answer, and saying so before the rebase is better than afterwards.
What to put on the prescription
Tick Rebase under Procedure, and describe why — accumulated repairs, porosity, staining, thinning from previous relines.
Note the condition of the teeth so the laboratory can flag anything that would make a remake the better option. Say whether the occlusion or vertical dimension is being changed.
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