7), expose only very superficially collagen on dentin and create a nano-interaction zone [28]. Glass ionomers (polyalkenoates) were probably the first successful dentin-bonding agents. They are the only truly self-adhesive materials that can adhere to both enamel and dentin [29]. An acid–base reaction is created between an acid-soluble Ca–Al–F–Si glass and a polyalkenoic acid (originally polyacrylic acid). The carboxyl groups on the polymeric acid react with the calcium and aluminium ions released from the glass, resulting in hardening [30]. Similar to self-etch adhesives, glass ionomers have a two-fold adhesive capacity that

depends both on the limited demineralization of enamel and dentin with subsequent infiltration and micromechanical interlocking, and on chemical adhesion between

the polyalkenoic acid and hydroxyapatite. The demineralization reaction is initiated by a high-molecular-weight polyalkenoic acid, which exposes the microporous collagen network this website by selectively dissolving hydroxyapatite crystals. Additionally, ionic bonding takes place between the carboxyl groups of the polyalkenoic acid and the calcium in the remaining hydroxyapatite crystals [31]. In general, considerably higher bond strengths have been reported for self-etch adhesives compared with glass ionomer systems [32]. However, it is difficult to compare bond strength data unless the materials have been tested in an identical manner. Longitudinal clinical trials are the final arbiter of the efficacy Talazoparib nmr of dental restorative materials; however, they are expensive, time consuming and difficult to standardize. In addition, the rapid introduction of new adhesive-bonding systems has increasingly forced dentists

to rely on laboratory tests for the evaluation of these products. Bend, impact, cleavage, peel, lap shear and tensile tests (orthodontic bracket/enamel selleck systems) are most commonly employed for bond-strength evaluation, whereas the efficacy of dentin-bonding agents is mainly evaluated by tensile and/or shear bond-strength measurements [33]. The reliability and validity of tensile and shear-bond strength determinations for the dentin-bonded interface have been questioned [34]. Much of the research related to dentin bonding has attempted to assess the integrity and strength of the interfacial bond. Experimental approaches for the measurement of adhesive bond strengths in dentistry have consisted primarily of tensile or shear-bond strength determinations performed within a defined area in vitro. Although the testing procedures appear to be similar, the results of studies can differ tremendously, as discussed in more detail below. Although the coefficient of variation associated with bond-strength data is known to be high (commonly >30%), the differences are weakly statistically significant [35]. Large variations in the methods used for bond-strength determinations and the lack of standardized laboratory test procedures have contributed to ambiguities in data interpretation.