The immediate bonding effectiveness of contemporary adhesives is quite favorable, regardless of the approach used. In the long term, the bonding effectiveness of some adhesives drops dramatically, whereas the bond strengths of other adhesives are more stable. This review examines the fundamental processes that cause the adhesion of biomaterials to enamel and dentin to degrade with time. Non-carious class V clinical trials remain the ultimate test method for the assessment of bonding effectiveness, but in addition to being high-cost, they are time- and labor-consuming, and they provide little information on the true cause of clinical failure. Therefore, several laboratory protocols were developed to predict bond durability. This paper critically appraises methodologies that focus on chemical degradation patterns of hydrolysis and elution of interface components, as well as mechanically oriented test set-ups, such as fatigue and fracture toughness measurements. A correlation of in vitro and in vivo data revealed that, currently, the most validated method to assess adhesion durability involves aging of micro-specimens of biomaterials bonded to either enamel or dentin. After about 3 months, all classes of adhesives exhibited mechanical and morphological evidence of degradation that resembles in vivo aging effects. A comparison of contemporary adhesives revealed that the three-step etch-and-rinse adhesives remain the 'gold standard' in terms of durability. Any kind of simplification in the clinical application procedure results in loss of bonding effectiveness. Only the two-step self-etch adhesives approach the gold standard and do have some additional clinical benefits.

http://www.endoexperience.com/documents/DeMunketalDurabiltyofadhesionJDR.pdf

A Critical Review of the Durability of Adhesion to Tooth Tissue: Methods and Results

Bonding to tooth tissue can be achieved through an "etch&rinse," "self-etch" or "glass-ionomer" approach. In this paper, the basic bonding mechanism to enamel and dentin of these three approaches is demonstrated by means of ultramorphological and chemical characterization of tooth-biomaterial interfacial interactions. Furthermore, bond-strength testing and measurement of marginal-sealing effectiveness (the two most commonly employed methodologies to determine "bonding effectiveness" in the laboratory) are evaluated upon their value and relevance in predicting clinical performance. A new dynamic methodology to test biomaterial-tooth bonds in a fatigue mode is introduced with a recently developed micro-rotary fatigue-testing device. Eventually, today's adhesives will be critically weighted upon their performance in diverse laboratory studies and clinical trials. Special attention has been given to the benefits/drawbacks of an etch&rinse versus a self-etch approach and the long-term performance of these adhesives. Correlating data gathered in the laboratory with clinical results clearly showed that laboratory research CAN predict clinical effectiveness. Although there is a tendency to simplify bonding procedures, the data presented confirm that conventional three-step etch&rinse adhesives still perform most favorably and are most reliable in the long-term. Nevertheless, a self-etch approach may have the best future perspective. Clinically, when adhesives no longer require an "etch&rinse" step, the application time, and probably more importantly, the technique-sensitivity are substantially reduced. Especially "mild," two-step self-etch adhesives that bond through a combined micromechanical and chemical interaction with tooth tissue closely approach conventional three-step systems in bonding performance.

Buonocore memorial lecture, adhesion to enamel and dentin: current status and future challenges

Systematic review of the chemical composition of contemporary dental adhesives

Dental adhesion review: Aging and stability of the bonded interface

http://webdelprofesor.ula.ve/odontologia/robertramirez/PDF/1.pdf

State of the art of self-etch adhesives

The importance of the interdental anatomy of a class-2 direct composite restoration is one of the most underestimated topics in direct posterior composite restorations. The proximal emergence profile of the restoration and the contact area should be designed to maximize arch continuity and to minimize food impaction. Other restorative criteria that must be fulfilled are marginal adaptation compatible with the dental and periodontal integrity, and geometry of the marginal ridge compatible with the mechanical integrity of the restoration under load. Shortcomings will result in masticatory discomfort, caries, periodontal problems and undesired movement of teeth. In vitro and in vivo studies showed that the use a contoured sectional metal matrix band with a separation clamp results in the tightest contact point. However, this matrix system also has shortcomings and does not give the expected result in all class-2 cavities. The variation in depth, width of the box, distance between the cervical cavity margin and the adjacent tooth requires customization of the interproximal space. In order to realize this, sectional matrix bands with several profiles of curvature, variation of wedges and separation clamps, and the use of teflon tape are required. In addition, dentists should follow a protocol allowing them to build a proximal composite surface that fulfills the required restorative criteria. Pre-wedging, space evaluation, interproximal clearance, correct selection, positioning and stabilization of the matrix band are important steps in this protocol.

Bart Van Meerbeek

Papers

Effective Protocol for Daily High-quality Direct Posterior Composite Restorations. The Interdental Anatomy of the Class-2 Composite Restoration.

Bonding effectiveness of new self-etch adhesives to bur-cut enamel and dentin

Micro-tensile bond strength of a contemporary total-etch and self-etch adhesive after in vivo degradation

Bonding effectiveness and morphological characterization of one-step self-etch adhesives

Predominant failure underneath hybrid layer with mild self-etch adhesives after aging