344H
Fig. 8.7 Distal-occlusal restorations on both lower second
primary molars after 3 years⎯one restored with conventional
amalgam, the other with glass ionomer cement.
8.5.2 New restorative materials
Recently, a number of new materials have come on to the market which aim to
maximize the best qualities of both composite resins and glass ionomers. Some of
these show promise and should be considered for the restoration of children's teeth.
None of them have had more than 3-4 year clinical trials so it is still unclear how
valuable they are compared to conventional materials.
They can be classified according to whether they retain the essential acid-base
reaction of the glass ionomers or not.
Resin-modified glass ionomer
These consist of a glass ionomer cement to which has been added a resin system that
will allow the material to set quickly using light or chemical catalysts (or both) while
allowing the acid-base reaction of the glass ionomer to take place. Thus, the materials
will set, albeit rather slowly, without the need for the resin system and the essential
qualities of a glass ionomer cement should be retained (345HFig. 8.8).
Polyacid-modified composite resin (Compomer)
In contrast, these materials have a much higher content of resin and the acid-base
reaction of the glass ionomers does not take place. Therefore although they are easier
to use (being premixed in capsules), there is some doubt as to the longer term benefits
over conventional composite resins (346HFig. 8.9). However, recently published work has
shown compomer to be as durable as amalgam after 3 years in approximal cavities in
primary molars (Marks et al. 1999; Welbury et al. 2000).