New techniques and materials will always emerge in the market, but it is essential for
the practitioner to be sceptical until researchers report clinical trials of adequate
design and duration. Extrovert exponents of a particular technique or material
frequently sway us into purchasing a material prematurely, but to our cost later.
Glass ionomer cements
This group of materials tend to be more brittle than composites, but have the
advantage of adherence to both enamel and dentine without etching. The coefficient
of expansion of glass ionomer is very close to that of dentine and once set, these
materials remain dimensionally stable in the mouth despite constantly changing
moisture and temperature levels. Their biggest advantage over composites is that they
are able to release fluoride over an extended period of time. Their lack of strength
limits their use in the permanent dentition but they can be used in PRRs where there is
no occlusal load and as an interim restoration while caries is brought under control
(452HFigs. 9.22 and 453H9.23). They are also the authors' choice of material for cementing
stainless-steel crowns.
Resin-modified glass ionomer
Reinforcement of glass ionomer with resin has been used to produce a fast setting
cement but these materials require etching prior to placement. On modifying the
materials, fracture toughness/resistance and abrasion resistance improve, and they still
retain biocompatibility, fluoride ion hydrodynamics, favourable thermal expansion
and contraction characteristics, and most important of all, they retain physico-
chemical bonding to tooth structure.
Compomer (polyacid-modified resin-based composite)
These materials are a combination of composite and ionomer. They have better
aesthetics than glass ionomer as a single material and have the advantage of some
fluoride release, but there is still a need to etch during the restorative procedure.
However, it would appear that they suffer from the disadvantages of loss of retention
together with gap formation between the material and tooth substance. Despite these
generally accepted limitations there is one recent report of a 92.3% success rate using
compomer in stress bearing restorations in permanent posterior teeth. Further studies
will clarify the issue.
454H
Fig. 9.21 After restoration with
amalgam, place fissure sealant to cover
the amalgam and seal the fissure
system.