DENTAL ADHESIVES: QUESTIONS ANSWERED

CONTEMPORARY PROTOCOLS FOR ACID AND DENTAL ADHESIVE APPLICATION

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 previous application methods, facilitating clinical steps and offering better results. Following those new trends is decisive for the best use of the modern dental materials and to achieve the best results. Here are the answers for the dentists’ main questions.

Did you know that the duration of the acid etching on the dentin has been decreasing?

Acid etching is believed to have a great demineralization potential, however, there is a lot of difficulty for the dental dental adhesive to penetrate the demineralized dentin. When acid etching is carried out on the dentin, there is also the release of enzymes that degrade collagen fibrils with time. For those reasons, acid etching of the dentin is being phased out. In case you use an dental dental adhesive that requires previous etching with phosphoric acid, we recommend the application on the dentin for a maximum of 5 seconds.

1: Stape THS, Wik P, Mutluay MM, Al-Ani AAS, Tezvergil-Mutluay A. Selective dentin etching: A potential method to improve bonding effectiveness of universal dental 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 dental adhesive systems. Dent Mater. 2016 Feb;32(2):e9-21.

Why are these new adhesives called “universal”?

The name comes from the fact that, since those materials have MDP in their composition, it is suggested that they may be used not only as dental adhesive systems for direct restorations but also as ceramic/metallic primer under the piece in indirect restorations. The MDP group bonds with metallic ions available on the surface of metallic and ceramic pieces and achieves a long-lasting adhesion. Nevertheless, it does not mean that the universal dental adhesive has “silane”. There are universal dental adhesives that do, but, in this case, due to their acid pH, there is an inactivation of the silane. In short: universal dental adhesives that contain silane cannot be relied on for this function! FGM’s dental adhesive line does not contain silane in its formula.

1: Perdigão J, Loguercio AD. Universal or Multi-mode Dental adhesives: Why and How? J Adhes Dent. 2014 Apr;16(2):193-4. 2: 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’ dental adhesives. Dent Mater. 2016 Oct;32(10):1218-1225.

How do universal dental adhesives function with dentin that has been affected by cavities or erosion?

Dentin that has been eroded by a tooth decay or frequent ingestion of erosive fluids is always more difficult to be adhered to. However, recent studies have shown that, as this dentin has already been “attacked” and therefore is more porous, phosphoric acid is not necessary. The application of a universal dental adhesive with MDP in the self-etching mode is the best way to achieve adhesion.

1: Hass V, Cardenas A, Siqueira F, Pacheco RR, Zago P, Silva DO, Bandeca MC, Loguercio AD. Bonding Performance of Universal Dental adhesive Systems Applied in Etch-and-Rinse and Self-Etch Strategies on Natural Dentin Caries. Oper Dent. 2019 Sep/Oct;44(5):510520. 2: Siqueira FSF, Cardenas AM, Ocampo JB, Hass V, Bandeca MC, Gomes JC, Reis A, Loguercio AD. Bonding Performance of Universal Dental adhesives to Eroded Dentin. J Adhes Dent. 2018;20(2):121-132.

What would be an alternative for not using phosphoric acid on the dentin?

Use a self-etching dental adhesive, or, a more recent product, a universal dental adhesive. Universal dental adhesives contain acid monomers which make a superficial modification in the smear layer and dentin, forming a hybrid layer that is thinner, but very resistant, which is the same as happens with self-etching dental adhesives. Since a part of those acid monomers (MDP) chemically bond with the calcium in the dentin (MDP phosphate group), it is no longer necessary to etch the dentin. Unfortunately, not many dental adhesives contain MDP. The whole line of FGM dental adhesive does, and that is why it is a great choice!

1: Hass V, Cardenas A, Siqueira F, Pacheco RR, Zago P, Silva DO, Bandeca MC, Loguercio AD. Bonding Performance of Universal Dental adhesive Systems Applied in Etch-and-Rinse and Self-Etch Strategies on Natural Dentin Caries. Oper Dent. 2019 Sep/Oct;44(5):510-520. 2: Siqueira FSF, Cardenas AM, Ocampo JB, Hass V, Bandeca MC, Gomes JC, Reis A, Loguercio AD. Bonding Performance of Universal Dental adhesives to Eroded Dentin. J Adhes Dent. 2018;20(2):121-132. 3: Loguercio AD, Muñoz MA, Luque-Martinez I, Hass V, Reis A, Perdigão J. Does active application of universal dental adhesives to enamel in self-etch mode improve their performance? J Dent. 2015 Sep;43(9):1060-1070. 4: Muñoz MA, Luque-Martinez I, Malaquias P, Hass V, Reis A, Campanha NH, Loguercio AD. In vitro longevity of bonding properties of universal dental adhesives to dentin. Oper Dent. 2015 May-Jun;40(3):282-92.

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

It is not true. For the MDP to remain ionized, it is crucial that those materials contain water in their composition. That may lead one to imagine that, if you dry the dentin, the water from the universal dental adhesive would re-moisturize the dentin. On the other hand, if the dentist leaves the cavity too moist and applies an dental adhesive that contains water, there may be excess moist, which would be detrimental for the obtainment of a resistant hybrid layer. That problem may be compensated through different strategies. One of them is in the FGM dental adhesive line: the APS technology. It has already been demonstrated that, with the use of APS dental adhesives, which contain more hydrophilic photoinitiators, higher conversion rates are reached, even when there is a very moist substrate, such as the apical region during the cementation of a fiberglass post. That is an important advantage of the Ambar APS and Ambar Universal APS.