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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.

What are the other advantages of the APS technology?

Besides improving polymerization of the Ambar APS and Ambar Universal APS dental adhesives, the APS technology has allowed for the production of a transparent dental adhesive due to the very low concentration of camphorquinone. This is important in esthetic restorations such as veneers and no-prep veneers in which the piece is very thin. The use of a “yellowish” dental adhesive could interfere in the final shade of the restoration. The choice of a transparent dental adhesive such as Ambar APS and Ambar Universal APS facilitates the achievement of excellent esthetic results

1: Oliveira OF Jr, Kunz PVM, Baratto Filho F, Correr GM, Cunha LFD, Gonzaga CC. Influence of PreCuring Different Dental adhesives on the Color Stability of Cemented Thin Ceramic Veneers. Braz Dent J. 2019 Jun;30(3):259-265.

Author: Alessandro Dourado Loguercio

Anatomization of dental post: The best choice for canals that are wide or have a differentiated anatomy.

Authors: Andréia Luiza Gabriel and Rayane Alexandra Prochnow

 

Teeth that undergo endodontic treatment with large coronary destruction are common in the dental practice and, in those cases, it is critical to recommend intra-radicular retainers for the reestablishment of their mechanical resistance.

Dental posts have been widely accepted and used. They present an elasticity module that is similar to that of the dentin, they absorb tensions generated by the masticatory forces and protect the radicular remains, allowing for the construction of a mechanically homogenous unit. However, the use of pre-manufactured dental post in wide canals or in canals with a differentiated anatomy may be considered critical when there is a substantial lack of adaptation and a thick line of cementation.

 

Thicker layers of cement are prone to flaws due to the presence of bubbles and to the increase in tension caused by the shrinkage of polymerization, responsible for the occurrence of fracture lines, which may lead to the dislocation of the dental post once the bonding strength is compromised. To improve the adaptation in wide canals, FGM developed the dental posts type DC-E which have a thin apical portion and a conservative cervical portion that is wider and more resistant.

In spite of the more adequate format, canals with a differentiated anatomy (exaggerated amplitude and not conical/oval) are frequently found and, in those cases, the best choice is to perform a technique called anatomic dental post. That technique involves the use of a composite to mold the root canal in order to decrease the cementation line.

 

Composites have high resistance to compression when they occupy the spaces between the wall of the canal and the dental post, leading to excellent retention. When using that technique, the polymerization of the composite happens aside from the cementation process, eliminating the risk of fractures from the polymerization shrinkage and without adding cementation lines (in cases when accessories for the adaptation of the dental post are used, for example), increasing longevity.

Check the step-by-step

Authors: Renata Paranhos Milioni, Leandro de Moura Martins, Gustavo Oliveira dos Santos and Raphael Monte Alto

After cleaning the retainer (Whitepost dental post – FGM), apply silane, apply the adhesive (Ambar Universal APS – FGM), light cure for 20 seconds.

Apply composite on the dental post and isolate the canal with hydro-soluble lubricating gel. Position the dental post inside the canal and light cure for 40 seconds. After complete light curing, make the core build-up. Remove the anatomized dental post and the core and cement with Allcem Core (FGM).

With the anatomization of the dental post, a single line of cementation with small thickness is achieved, minimizing the possibility of adhesive flaws.

Esthetic restorations in severely darkened anterior teeth using dental cement and fiberglass post

Authors: Raphael Monte Alto, Juliana Ferreira Batista Pereira, Mariana Ferreira Silva Ventura, Priscilla Carvalhal de Oliveira and Fabrício Perucelli.

 

Darkened teeth are always a challenge in the clinical routine, and when deciding the type of treatment, one should always select the most conservative one. In this context, whitening becomes an interesting alternative. However, due to the great relapse of this type of treatment, the patient usually ends up choosing a more definite solution such as crowns and veneers.

 

CASE REPORT

A female patient attended the subject of Integrated Clinic of the Fluminense Federal University (Rio de Janeiro – Brazil) indicated by the Discipline of Orthodontics with the application of an anterior crown with the appropriate format for future orthodontic finalization.

 

Endodontically treated teeth are susceptible to biomechanical failures especially when there is a significant loss of dental structure1. In such cases, the use of intraradicular retainers is necessary, mainly because the remnant structure is insufficient to adequately support and retain the final restoration2,3. Several techniques are available for the restoration of teeth with endodontic treatment and within this context choosing an inadequate method when restoring these teeth may compromise their longevity.

 

The tooth to be restored presented a good amount of coronal structure and conservative endodontic treatment, and the direct technique was indicated (see table 1).

 

The root canal was cleaned and dried with paper cones for the adhesive procedure and light-curing was performed for 40 seconds. With the aid of an insertion tip, Allcem Core dual cement (FGM) was applied in the root canal from the apical region to the coronary chamber.

 

The dental post Whitepost (FGM) DC-E 2 was inserted and the set was light cured for 40 seconds. The excess of the dental post was cut and the occlusal adjustments were performed. The patient was submitted to periodontal surgery by Professor Ronaldo Barcellos at the Fluminense Federal University (Rio de Janeiro – Brazil). After 90 days, total crown preparation and molding were performed and sent to the laboratory. A total crown was made with composite for CAD/CAM with external characterization. After tests and adjustments the crown was cemented.

 

Technique Indications Advantages Disadvantages
Direct. Teeth with a lot of coronary remnants. • Single section.
• Low cost.
Large amount of resinous cement.
Anatomical or direct modeling • Teeth with little remnants.
• Broad root canals.
• Single session.
• Low cost.
• Less quantity of cement.
• Less effect of the shrinkage stress.
• Certainty of polymerization of the composite throughout the post.
• Most critical technique.
• Need to create expulsivity in the root canal.

Table 1 – Indications, advantages and disadvantages of each technique. Table from the book “Reabilitação estética anterior: o passo a passo da rotina clínica (Raphael Monte Alto e Colaboradores)”.

 

CLINICAL PHOTOS

COMPOSITE RESIN SHADE SELECTION

What steps should one follow to apply the principles of optical properties and achieve the “perfect shade”? Find below a simplified step by step to help you achieve successful restorations.

 

The dental office should be lighted with “corrective” light with a color reproduction index of around 90 and average temperatures of 5500K (there are LED fixtures that hold lamps with those features). It is important to take the shade under another light source for confirmation and to avoid metamerism. Also, pay attention to other light sources to which the patients may be frequently exposed in relation to their activity profile.

 

  • Use neutral and light-colored walls, aprons and bibs, besides recommending that the patient refrain from using heavy make-up for the appointment, not to interfere or modify the perception of color by the observer.
  • Consider the effects of translucency and opacity in the distinct areas of a tooth for a balance of the optical effect of the different material thicknesses. For example, a thicker layer of enamel composite resin (more translucent) may result in a restoration with a lower value (grayish).

Vittra APS – Trans OPL (FGM) opalescent composite resin being tested on the incisal area. Note the high translucency.

 

  • In the case of using shade guides, use a single shade each time, and do not observe for more than a few seconds to avoid confusion and fatigue in the observer’s perception.
  • Anatomic shape, texture, flat areas and reflection lines should reproduce the adjacent teeth as faithfully as possible.

Fig 1 – Incisal third showing the greater proportion of light passage and lower amount of reflection. That area, as a rule, preferably should receive translucent enamel material (if necessary) and a thin layer of dentin material.

Fig 2 – Medium third: predominance of light reflection and little passage. That area, as a rule, should receive predominantly dentin material and a thinner enamel layer (0.5mm or less). Opaque material may be used for masking a darkened area.

Fig 3 – Cervical third, where there is the evident domain of light reflection with virtually no passage. In that area, it is possible to observe greater chroma or saturation and one should only use dentin material (opaque material, just to mask, if necessary, an eventual sclerotic dentin). The use of enamel material in that area may lead to a discrete graying of the restoration.

 

Simplified operatory plan:

 

  1. Prophylaxis with pumice stone paste/water for the dental surface to be clean and free of pigmented biofilm.
  2. Each and every shade taking should be prior to the isolation of the operatory field, since this installation dehydrates the dental element and temporarily increases its opacity.
  3. Select shade by value and not by hue. When placing a shade guide close to a tooth or applying composite resin increments on its surface, professionals should take a picture and digitally alter to a black and white filter. That way, the coordinates hue and chroma will be eliminated, there remaining only value or luminosity (fig. 7). In case the composite resin increment looks darker than the tooth, the professional can choose a lighter tone in the shade guide (from a value 3 shade, whatever the hue, to a value 2 one).

 

If it is lighter, the professional should do the opposite, and take a new black and white photo, until it looks right. Once the desired value is chosen, the professional may choose hue and a saturation. For example: value 2 was chosen and, if the tooth presents a whiter aspect, the choice will normally be A or B in the Vita guide (A being brownish yellow and B being yellow). If the tooth looks grayish, the professional may choose between C (gray) and D (grayish pink). With that, one avoids the confusion and doubt about different hues and a higher or lower saturation and different degrees of luminosity. The same methodology can be used in other shade guides that can be ordered by value or chroma degrees.

  1. Mapping areas of the tooth: teeth are polychromatic and may have distinct shade aspects in different regions. That should be observed clinically (higher or lower saturation) and with the aid of black and white photographs for areas of high or lower value/luminosity. Besides, professionals should note the degree of translucency in the different areas (incisal, medium and cervical). A black or light-blue piece of cardboard as a background may be used to help confirm that mapping. Many times, a second opinion is of great help before the final decision.
  2. In more complex cases, a quick direct mock-up (restoration without adhesive techniques) may help the definition of the thicknesses of each composite resin material.

Practically, all composites undergo a shade change when lightcured, going from a yellowish tone to a lighter tone. Therefore, it is important that those increments are cured before the photograph and clinical observation. Vittra APS (FGM) composite resin, thanks to its differentiated APS photoinitiators technology, does not show this perceptible shade variation between before and after light-curing. For that reason, it is possible to choose the shade before photopolymerization of the increment in real time.

Enamel (incisal third) and dentin (medium third) composite resin observed in normal photograph and in a black and white one used to help choosing the value of the composite resin.

Direct mock-up with the composites shown in figure 8, simulating the final restoration for a more refined evaluation of the selected shades.

Once the principles of optical properties are known and applied in the clinic in a simple and effective way, with the control over the thickness of the different composite resin

 

layers to be used, it is possible to achieve successful restorations that are esthetically pleasant.

Working towards the best appearance possible for restorations is common place among dental professionals. The article Shade Selection Aspects shows how you can pursue the perfect tooth shade in your office by analyzing the triad: light source, object and observer.

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SHADE SELECTION ASPECTS

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SHADE SELECTION RECOMMENDATIONS

What steps should one follow to apply the principles of optical properties and achieve the “perfect shade”? Find below a simplified step by step to help you achieve successful restorations.   • The dental office should be lighted with “corrective” light with a color reproduction index of around 90 and average temperatures of 5500K (there […]

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Esthetic restorations in severely darkened anterior teeth using dental post

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