Permanent dentures are the dentures that are fixed to the tooth, teeth, root stumps, or implants in the mouth. Therefore, it is not removable. It has various names – overdenture, hybrid denture and telescopic denture.
What are the indications for permanent dentures?
- It is especially indicated for young patients. The younger the patient is, the more suitable the patient is for overdenture because it is very aesthetically pleasing.
- When retention is difficult for removable dentures, such as when the patient has very resorbed ridges. A ridge is the bone in the upper and lower jaw that holds to the teeth. When the teeth are extracted, they will be filled with blood, and slowly be replaced by new bone. Ultimately, it will be resorbed. And this resorption rate differs with each individual, and also with each areas of the mouth in the same individual. Bone resorption rate depends on a few factors, and some individual will have no resorption in a long time, while some individual will have rapid resorption within a short period of time.
- When there is a complete loss of teeth in the upper arch, and there is an incomplete loss of teeth in the lower arch.
What is the process for fabricating a permanent denture?
There are two types of processing for every type of dentures in dentistry – the clinical procedure, and the laboratory procedure. This article is focused mainly on the clinical procedure, but it is important that laboratory procedures goes smoothly as well. Good communication and collaboration is needed between the dentist and the technician for a good denture to be produced.
There are two ways of retaining a permanent denture inside the mouth – by using the existing tooth or teeth or root stumps, or by inserting implants into the mouth. When using implants as abutments (the ‘teeth’ that holds on to the overdenture) , the implants can either be linked together by a bar, and the overdenture will clip on to the bar, or the overdenture can be screwed directly onto the implants. Whenever possible, a straight bar should be used as it limits the rotational movement of the overdenture, and thus making it more stable and comfortable to the patient.
If natural tooth or teeth or root stumps are used as abutments, root canal treatment has first to be done on those teeth and root stumps. This is because these tooth structures will be cut down later to receive the permanent denture. If root canal treatment in not done now, and if it is needed in the future, the permanent denture has to be remade. In some cases, these remaining teeth has also erupted too much due to the absence of the opposing teeth, therefore, root canal treatment is needed so that when the dentist cut away a large part of the tooth, the patient will not feel any sensitivity or discomfort.
After the teeth has been root canal treated, the tooth or teeth will be cut down, so that the permanent denture can fit over them like a crown or a bridge. An impression is taken after the teeth has been cut down, and the impression is sent to the lab to be casted. After the impression has been casted, it is now known as a model which is an exact replica of the patient’s mouth. This allows the denture to be fabricated on the denture, and the patient will be called to select the shade and the mould of the artificial teeth that suits the patient the best.
As some knowledge and understanding about implant is required to understand the whole procedure, more details can be enquired when visiting the dentist. But the basic procedure is as follow:
If an implant is placed inside the mouth, small metal caps which are known as the pick up impression copings are screwed onto the implants before taking the impression. And before removing the impression from the mouth, these metal caps are unscrewed so the they will be removed together with the impression. After removing the impression, a metal rod known as the analog will be screwed onto the metal cap. This analog impose as the real metal rod that will be found in the mouth, and after the impression has been casted, the models will again imitate the real situation of the patient’s mouth. This again, allows the denture to be fabricated on the model.
Albeit all the advantages of the permanent denture, some patient cannot tolerate it, and has poor acceptance towards it. The success of permanent dentures also depends largely on compliance of the patients in keeping the abutment teeth clean (if they are natural tooth or teeth or root stumps). This is because if caries or any loosening of the abutments are to occur, the permanent denture will not be stable any longer and will fail. In these cases with poor patient cooperation and acceptance, permanent dentures is not suitable for them.