Adhesive systems: important aspects related to their composition and clinical use

Abstract

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-andrinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SeM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

One-Year Evaluation of a Simplified Ethanol-Wet Bonding Technique: A Randomized Clinical Trial

“…In recent years, there has been a trend towards developing SE adhesives that required fewer steps and have decreased pH, taking to increased aggressiveness (11,14,16). However, systems with such combination of features had high hydrophilicity and short shelf lives (12).…”

“…Hence, the reduced aggressiveness became preferable again. Adper Easy One, used in the present study, has pH=2.3 and is classified according to acidity as a 'mild' OSSE system (14). Less acidic interfaces are less hydrophilic, but 'mild' SE systems exhibit poor demineralization ability, which can be considered a disadvantage, especially when enamel and sclerotic dentin conditioning are considered (2,12,14).…”

“…Theoretically, there is no or small difference between the depths of demineralization and resin infiltration induced by this system because both processes occur simultaneously (14)(15)(16). However, this adhesive strategy also has high hydrophilicity, which attracts water and compromises adhesive interface integrity (17,18).…”

Evaluation of degree of conversion, microtensile bond strength and mechanical properties of three etch-and-rinse dental adhesives

“…When using etchand-rinse adhesive systems, the surface and subsurface mineral components of dentin are removed totally by acid etching [1][2][3] . When the conditioning step is followed by a priming step and subsequent application of the adhesive resin, they are recognized and available as three-step adhesive systems.…”

“…In this single bottle there is a mixture of hydrophilic, hydrophobic monomers and solvent [3][4][5] . The presence of solvents favors the penetration of monomers into the collagen network and contributes to removing water [3] .…”