Restorative dentistry The flexible fix


to bridge the gap


Stuart Campbell and Paul Tipton present the first in a series of articles by the members of the British Academy of Restorative Dentistry (BARD)


Introduction Numerous types of fixed appli- ances are available for the replacement of missing teeth; however, some clinicians have reported that general prac- titioners could make better decisions when planning fixed bridgework ı. Poor bridge design carries a


high risk of failure and several authors have reported loss of cementation as being a major cause 2-4. Data from studies by Parfitt5


suggest that teeth may be depressed in their sockets by up


to 28μm, and when connected rigidly, as in bridgework, this differential movement may put considerable stress on the cement lute, leading to appli- ances becoming uncemented. The fixed/movable bridge is


effective in reducing cement failure. These appliances are supplied in two parts, and are cemented independently but interlock to create a non- rigid and hence movable joint. This two-part design provides a ‘stress-breaking’ action between the two parts of the bridge, reducing harmful


inter-abutment stresses and increasing clinical retention. (Figure ı – reproduced with permission from Quintessence Publishing – and Fig 2)


Indications and contraindications The fixed/movable bridge has a wide application, particularly where potential abutment teeth have been weakened by previous restorations or are mal-aligned. It is not appropriate in all


situations and is generally contraindicated where abut-


ment teeth are too small for the extent of preparation needed, and in aesthetically demanding patients, as metal may show occlusally. (Figure 3) Consideration should be


given to the presence of mobility in the abutment teeth, as this will act as a physiological stressbreaker, eliminating the need for this design in the bridge. One further contraindication is in the maxilla, where the abutments are unopposed. Subsequent over-eruption of one or both abutments may lead to loss of connection between both parts. The advantages and disad-


vantages are summarised in table ı (see page 57).


Bridge design The glossary of prostho- dontic terms6 describes the components of fixed/movable bridgework as follows:


Fig 1 Fixed/movable bridgework


Retainers Major retainer: The retainer


Scottish Dental magazine 55 Continued »


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