551HFigure 10.11 (a) and (b) show gold onlays cemented on to the lower first permanent
molars of a 16-year-old boy with erosive tooth surface loss. Such cast restorations
may be provided for both posterior and anterior teeth with very little or no tooth
preparation. Nevertheless, some children may find this treatment challenging as it
demands high levels of patient co-operation. Local anaesthesia may be needed as the
hypoplastic teeth are often sensitive to the etching and washing procedure and the
placement of gingival retraction cord can be uncomfortable. Furthermore, moisture
control can be difficult and, while preferable, rubber dam is not always feasible.
When used to protect the palatal aspect of upper anterior teeth there may be an
aesthetic problem as the metal may 'shine through' the translucent incisal tip of young
teeth. The durability of this form of restoration has now been confirmed by 10-year
evaluation studies.
552H
Fig. 10.11 (a) Marked occlusal enamel loss of lower first permanent molars. (b) Cast
occlusal onlays in situ after replacement of amalgam restorations with composite
resin.
10.2.10 Indirect composite resin onlays
An alternative to cast metal onlays are indirect composite onlays. In addition to the
obvious aesthetic advantages these restorations can be modified relatively easily. This
is particularly useful for conditions such as erosion where the disease process may
well be ongoing and therefore the tooth and/or restoration may require repair or
additions. Studies suggest that these restorations are durable in the anterior region,
however, in response to patient demand indirect composite onlays are increasingly
being used in the posterior region (553HFig. 10.12 (a)-(c)), where their durability is
currently unclear. The disadvantage of these restorations is that they need to be
thicker than their cast counterparts, are bulkier and can cause greater increases in
vertical dimension. However, in young patients, providing the occlusion remains
balanced and there is no periodontal pathology, then increases in vertical dimension
appear well tolerated.