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

Background: From an ecological viewpoint, the oral cavity, in fact the oro-pharynx, is an ‘open growth system’. It undergoes an uninterrupted introduction and removal of both microorganisms and nutrients. In order to survive within the oro-pharyngeal area, bacteria need to adhere either to the soft or hard tissues in order to resist shear forces. The fast turn-over of the oral lining epithelia (shedding 3 ×/day) is an efficient defence mechanism as it prevents the accumulation of large masses of microorganisms. Teeth, dentures, or endosseous implants, however, providing non-shedding surfaces, allow the formation of thick biofilms. In general, the established biofilm maintains an equilibrium with the host. An uncontrolled accumulation and/or metabolism of bacteria on the hard surfaces forms, however, the primary cause of dental caries, gingivitis, periodontitis, peri-implantitis, and stomatitis.

Objectives: This systematic review aimed to evaluate critically the impact of surface characteristics (free energy, roughness, chemistry) on the de novo biofilm formation, especially in the supragingival and to a lesser extent in the subgingival areas.

Methods: An electronic Medline search (from 1966 until July 2005) was conducted applying the following search items: ‘biofilm formation and dental/oral implants/surface characteristics’, ‘surface characteristics and implants’, ‘biofilm formation and oral’, ‘plaque/biofilm and roughness’, ‘plaque/biofilm and surface free energy’, and ‘plaque formation and implants’. Only clinical studies within the oro-pharyngeal area were included.

Results: From a series of split-mouth studies, it could be concluded that both an increase in surface roughness above the Ra threshold of 0.2 μm and/or of the surface-free energy facilitates biofilm formation on restorative materials. When both surface characteristics interact with each other, surface roughness was found to be predominant. The biofilm formation is also influenced by the type (chemical composition) of biomaterial or the type of coating. Direct comparisons in biofilm formation on different transmucosal implant surfaces are scars.

Conclusions: Extrapolation of data from studies on different restorative materials seems to indicate that transmucosal implant surfaces with a higher surface roughness/surface free energy facilitate biofilm formation.

Effect of material characteristics and/or surface topography on biofilm development

Dental adhesion review: Aging and stability of the bonded interface

http://webdelprofesor.ula.ve/odontologia/robertramirez/PDF/3

Marleen Peumans

Papers

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

Systematic review of the chemical composition of contemporary dental adhesives

Clinical effectiveness of contemporary adhesives: a systematic review of current clinical trials.

Relationship between bond-strength tests and clinical outcomes

Porcelain veneers: a review of the literature.