25/09/2024

5 Questions About Dental Adhesives and Contemporary Protocols

With the increasing number of studies on the preparation of the dental structure for better adhesion of dental materials, new protocols and applications are studied, modifying old forms of application, facilitating clinical steps and providing better results.

Keeping up with these new trends is crucial to make the best use of modern dental materials and to obtain the best results. The main doubts of dentists are addressed below.

Did you know that the acid etching time in dentin has decreased?

Acid etching is considered to have a great potential for demineralization, however, there is great difficulty in the penetration of the adhesive through the demineralized dentin layer. When acid etching is performed on dentin, enzymes are also released, which degrade the collagen fibrils over time. For these reasons, acid etching of dentin is falling into disuse. If you are going to use an adhesive that requires the prior use of phosphoric acid, apply it to the dentin for a maximum of 5 seconds.

Why are these new adhesives called “universal”?

This name comes from the fact that, since these materials have MDP in their composition, it is suggested that they can be used not only as adhesive systems for direct restorations, but also as a ceramic/metallic primer under the tooth in indirect restorations. The phosphate group of MDP binds to metal ions available on the surface of metal and ceramic pieces and achieves a long-lasting adhesion.

However, it does not necessarily mean that the universal adhesive has “silane”. There are universal adhesives that contain it, but, due to their acidic pH, an inactivation of this silane occurs. In short: universal adhesives containing silane are not reliable to be used for this purpose! The FGM adhesive line does not have silane in the adhesive composition.

What would be the option to avoid using phosphoric acid on dentin?

Use a self-etching adhesive, or more recently, a universal adhesive. Universal adhesives contain acidic monomers that modify the surface of the smear layer and dentin, forming a hybrid layer that is thinner but very resistant, as is the case with self-etching adhesives. As part of these acidic monomers (MDP) chemically bind to the calcium in dentin (phosphate grouping of MDP), etching of the dentin is no longer necessary. Unfortunately, there are not many adhesives that contain MDP, but the entire FGM adhesive line contains it and therefore they are an excellent choice!

Is it true that all universal adhesives are less susceptible to humidity variations?

This is not true. In order for the MDP to remain ionized, it is essential that these materials contain water in their composition. This makes one imagine that if you dry the dentin further, the water in the universal adhesive itself could re-wet this dentin. On the other hand, if the dentist leaves the cavity too moist and applies an adhesive containing water, it can cause excess moisture, which would be detrimental to obtaining a resistant hybrid layer.

This problem can be compensated for by different strategies: one of them is contained in the FGM adhesive line, the APS technology. It has already been demonstrated that, with the use of adhesives with APS, which contains more hydrophilic photoinitiators, high conversion degree values are achieved, even when there is a very humid substrate, such as, for example, in the apical region during the cementation of a fiberglass post. This is an important advantage of the Ambar APS and Ambar Universal APS lines.

Ambar APS and Ambar Universal APS have the exclusive APS technology, a system that guarantees high adhesion in any dentin humidity condition. A smart and aesthetic adhesive line, which offers excellent performance for both the specialist and the clinician.

References

Stape THS, Wik P, Mutluay MM, Al-Ani AAS, Tezvergil-Mutluay A. Selective dentin etching: A potential method to improve bonding effectiveness of universal adhesives. J Mech Behav Biomed Mater. 2018 Oct;86:14-22.
2 – Takamizawa T, Barkmeier WW, Tsujimoto A, Berry TP, Watanabe H, Erickson RL, Latta MA, Miyazaki M. Influence of different etching modes on bond strength and fatigue strength to dentin using universal adhesive systems. Dent Mater. 2016 Feb;32(2):e9-21.
Hass V, Cardenas A, Siqueira F, Pacheco RR, Zago P, Silva DO, Bandeca MC, Loguercio AD. Bonding Performance of Universal Adhesive Systems Applied in Etch-and-Rinse and Self-Etch Strategies on Natural Dentin Caries. Oper Dent. 2019 Sep/Oct;44(5):510-520.
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Loguercio AD, Muñoz MA, Luque-Martinez I, Hass V, Reis A, Perdigão J. Does active application of universal adhesives to enamel in self-etch mode improve their performance? J Dent. 2015 Sep;43(9):1060-1070.
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Hass V, Cardenas A, Siqueira F, Pacheco RR, Zago P, Silva DO, Bandeca MC, Loguercio AD. Bonding Performance of Universal Adhesive Systems Applied in Etch-and-Rinse and Self-Etch Strategies on Natural Dentin Caries. Oper Dent. 2019 Sep/Oct;44(5):510-520.
Siqueira FSF, Cardenas AM, Ocampo JB, Hass V, Bandeca MC, Gomes JC, Reis A, Loguercio AD. Bonding Performance of Universal Adhesives to Eroded Dentin. J Adhes Dent. 2018;20(2):121-132.
Perdigão J, Loguercio AD. Universal or Multi-mode Adhesives: Why and How? J Adhes Dent. 2014 Apr;16(2):193-4.
Yoshihara K, Nagaoka N, Sonoda A, Maruo Y, Makita Y, Okihara T, Irie M, Yoshida Y, Van Meerbeek B. Effectiveness and stability of silane coupling agent incorporated in ‘universal’ adhesives. Dent Mater. 2016 Oct;32(10):1218-1225.
Oliveira OF Jr, Kunz PVM, Baratto Filho F, Correr GM, Cunha LFD, Gonzaga CC. Influence of Pre-Curing Different Adhesives on the Color Stability of Cemented Thin Ceramic Veneers. Braz Dent J. 2019 Jun;30(3):259-265.