In this part, we will discuss
Repairs and additions
This article describes measures designed to provide short-term solutions to existing RPD problems and to establish an optimum oral environment for the provision of definitive prostheses.
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Initial prosthetic treatment may involve modification of an existing denture or provision of an interim prosthesis as a preparation for the definitive course of treatment.
When modifying existing dentures the following points should be borne in mind. Firstly, as these dentures are commonly due for early replacement, modifications will not have to last for very long. Secondly, the patient will often be reluctant to part with the denture for the modifications to be carried out, particularly if it replaces anterior teeth. These considerations point to modification of the denture at the chairside wherever practicable. A range of polymers for direct use in the mouth significantly increases the number of opportunities for adopting this approach. Their relatively short clinical life, usually measured in months rather than years, is not a problem where early replacement of the denture is anticipated.
Repairs and additions
Before undertaking a repair it is essential to determine the cause of the fracture so that appropriate corrective measures can be undertaken.
The addition of a new artificial tooth may be required to fill a space created either by loss of a denture tooth or by extraction of a natural tooth. This is often best done by obtaining an alginate impression and interocclusal records, as described in Fig. 1, so that the addition can be made in the laboratory.
Alternatively, it may be possible to rapidly achieve an acceptable result by building up a replacement tooth by direct additions of tooth-coloured cold-curing acrylic resin to the denture at the chairside.
The acrylic base of an RPD may be relined temporarily where loss of fit has resulted in instability or mucosal injury.
Temporary relining is carried out in the mouth using either soft or hard materials. When mucosal inflammation is present, the cushioning effect of the short-term soft materials (tissue conditioners) is an advantage in that it distributes the load more evenly and thus promotes healing. The hard materials have been mentioned in Fig. 7.
Before undertaking a temporary reline, preparatory adjustment of the denture is commonly necessary.
As all these linings are added as a temporary measure, a positive decision must be taken by the dentist as to the next stage of treatment. For example, a short-term soft lining material needs to be assessed at approximately weekly intervals and replaced periodically until mucosal inflammation has resolved. A new denture can then be constructed.
An interim prosthesis may be constructed before the definitive denture for the following reasons.
Space maintenance and aesthetics.
Improving patient tolerance.
Preparation for advanced restorative treatment.
Modifying jaw relationships.
Preparation for advanced restorative treatment
A factor vital to the success of advanced restorative treatment is the ability of the patient to maintain a high level of plaque control. The use of an interim prosthesis will permit a careful evaluation of the oral and denture hygiene over a prolonged period before definitive treatment is commenced.
Advanced prosthetic treatment can fail because of a patient's unrealistic expectation of what a removable prosthesis can achieve, creating dissatisfaction and rejection of the treatment that has been undertaken. The provision of an interim prosthesis gives the patient experience of the limitations of such dentures; this experience, when combined with careful explanation of future treatment aims and expectations, helps to create a more realistic frame of mind and readier acceptance of the definitive prosthesis.
Modifying jaw relationships
Adaptive changes in the jaw relationship may result from loss of teeth, the excessive loss of tooth substance or the congenital absence of teeth. These changes may require correction before restorative treatment can be undertaken and this may be achieved by the progressive occlusal adjustment of an interim prosthesis until the optimum occlusal relationship is determined.
Treatment of denture stomatitis
The commonest causes are an overgrowth of the fungus Candida albicans encouraged by poor denture hygiene and mechanical trauma from the denture. Systemic conditions, such as diabetes, deficiencies of iron, vitamin B12 or folic acid, and drug therapy, including broad-spectrum antibiotics, steroids and cytotoxic agents, may predispose to denture stomatitis.
Treatment of the condition to achieve resolution of the inflammation and the associated mucosal swelling should be carried out before working impressions are obtained.
Toxins produced by the Candida cells left on the denture surface by deficient hygiene measures, together with trauma from the denture, initiate an inflammatory reaction. Thinning of the mucosa results in increased permeability and escape of inflammatory exudate. The exudate, together with desquamated mucosal cells, forms a favourable nutrient medium, which promotes the growth of Candida albicans. In addition, this exudate, and the sucrose-rich diet which may result from the dietary selection sometimes associated with the wearing of dentures, may contribute to the condition by increasing the adhesiveness of the Candida cells, and thus encouraging the formation of denture plaque. As candidal proliferation occurs, the rate of production of potent toxins by the micro-organisms increases. The passage of these toxins into the tissues is facilitated by the thinning and increased permeability of the mucosa. Aggravation of the inflammatory response occurs and so a vicious circle is set up. Anti-candidal antibody is secreted in parotid saliva but the denture base may restrict access of antibody to the Candida cells.
If trauma appears to be a contributory factor to the stomatitis, appropriate adjustments, such as occlusal correction and temporary relining, should be made to the denture as described in the earlier sections of this chapter. However, it should be borne in mind that as temporary linings with tissue conditioners make it more difficult for the patient to keep the denture clean, they should be avoided if possible. As both plaque and traumatic factors can be eliminated by leaving the denture out the patient should be advised to do this as much as possible.
If the lesion does not respond to these local measures the investigation of possible systemic factors should be undertaken. In such refractory cases, oral antifungal agents such as Amphotericin B, Nystatin or Miconazole may be beneficial. It should be noted, however, that these antifungal agents by themselves are of very limited value and unless the underlying cause of the denture stomatitis is eradicated the condition will recur when the antifungal agents are withdrawn.
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Davenport, J., Basker, R., Heath, J. et al. Initial prosthetic treatment. Br Dent J 190, 235–244 (2001). https://doi.org/10.1038/sj.bdj.4800936