Conventional glass-ionomer cement adhesion

The clinical technique known as Atraumatic Restorative Treatment (ART) has been developed since the mid-1980s in response to dental clinical needs in Third World countries. It is an important application of adhesive dental materials, specifically conventional glass-ionomer cements, and would not be possible without this type of adhesive material (Frencken et al. 2004). ART involves the removal of carious tooth tissue with hand instruments rather than conventional dental drills. These hand-held instruments are formed as spoon-shaped excavators, and come in graded sizes. 

Laswell et al., 1971 Arato, 1974). All were prone to excessive dissolution and only one had adequate strength and film thickness. Their working characteristics were found to be unduly sensitive to changes in temperature and humidity (Simmons, D Anton Hudson, 1968). All were inferior to conventional zinc phosphate cements. No further development of these cements has taken place, nor is it likely that interest in them will be revived. The modem water-activated glass-ionomer cement has filled this niche and has vastly superior properties including adhesion to tooth material. 

The term polyacid-modifled composite resin was originally proposed for these materials by McLean et al. in 1994 [6], and was felt to be a more accurate description than the term compomer under which they had been first marketed. The latter word was coined as a hybrid of the terms composite and glass-ionomer , but lacked any indication that the materials in question more closely resembled conventional composite resins than glass-ionomer cements. In particular, they are formulated without any water present, and are substantially hydrophobic, albeit less so than conventional composite resins. Also, despite early claims, they show no inherent adhesion to the tooth surface, and have to be used in association with bonding agents of the type used with conventional composites [1,6]. 

One of the key features of polyacid-modified composite resins is their lack of adhesion to tooth tissnes [5]. This is a feature that they share with conventional dental composite resins, and the contrasts with the behaviour of the glass-ionomer cement. It is further evidence that these materials are essentially composite resins, and have very little of the anticipated hybrid character of composites and glass-ionomers. Bonding therefore reqnires the type of bespoke bonding agents used for conventional composite resins, together with the appropriate preparation of the freshly cut tooth surface [6]. 

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