Soft Linings for an acrylic base (plastic denture)
Are there soft base materials?
A base material itself cannot be soft exactly because it must be functional as well as ‘look the part’. However, if you have very sensitive tissue in your mouth you can request to have a soft layer of the special pink silicone incorporated into your acrylic denture. This will act as a cushioning layer between the hard acrylic denture and your gums. This is simply called a soft lining and may be available if it is suitable for the requested appliance. A soft lining can be added during the construction stages of a new appliance or added to an existing appliance. The lining itself can be applied to the entire contact surface or only part, dependent on requirement.
Does a soft lining have any other uses?
A soft lining can be useful not only for cushioning a denture but also for increasing the retention (grip). The softer material can be incorporated into a dental appliance to use spaces inside of the mouth where a patient would not be able to tolerate a rigid material alone.
Great! I want a super cushioned denture please!
OK, perhaps it sounds like everyone should have a soft lining as standard but sometimes it’s just not possible and I’ll try explain a little bit about why…
The soft lining material is not an addition to the hard acrylic, it is actually replacement for a certain amount, usually around 2 – 3 mm. Bear in mind the acrylic is the base material that not only holds the teeth in place, it is also the construct responsible for the strength and load spreading (during chewing etc). If too much acrylic is removed, it will dramatically weaken the appliance. That’s why some dentures are suitable and some are not.
Downsides to soft linings…
If the acrylic contact surface is not correctly prepared prior to processing, the soft lining can de-bond from the acrylic. If this happens, the denture will need to be sent back into the lab and the entire soft lining will need to be replaced as there are no quick ways to fix this in the surgery. Although the technician should have already done so before sending the denture out to the surgery, the dentist should always double check all of the way around between the two materials for any signs of de-bonding before the patient leaves the surgery. Any gaps will create food traps and ideal breeding grounds for oral bacteria.
Soft linings do have a limited life expectancy and they will gradually lose their ‘bounce’ over time. This means they will periodically need replacing. Personally I think this in itself isn’t actually that much of a bad thing, although admittedly the patient will be without their denture for a little while every so often, it does mean the patient returns to the surgery regularly and has their denture re-lined with new soft lining material every 12 months or so giving their denture a brand new and more accurate fitting surface.
Soft linings can also make denture maintenance a little more complex as they can pick up staining quite easily and are notoriously fickle about which cleaning products can be used without turning them into hard linings…!
A good idea would be, if you have a soft lining incorporated into an appliance, be sure to ask which brand of lining material has been used to help you select the most appropriate cleaning routine. An easy rule to apply generally if your appliance has a soft lining, avoid prolonged soaking in any appliance cleaning solution (no more than 15 minutes).