Can you etch zirconia

To preserve esthetics while also ensuring a strong bond, many clinicians are turning to resin cements. I also want product flexibility that promotes efficiency, because now I can use one product for many different clinical situations, rather than having to stock multiple products. Self-adhesive dual-cure resin cement has been found to be more effective than regular cements for ceramic crowns and bridges; in fact, one study found zirconia crowns were twice as likely to loosen when adhered with zinc-phosphate cement as opposed to a self-adhesive dual-cure resin cement.

But Dr. Lawson points out that not all zirconia restorations need to be bonded with a resin cement. In fact, a recent Practice Based Research Network study reported that only 30 percent of zirconia crowns were bonded with resin cement. New products, knowledge and technology are making zirconia bonding easier and more predictable than ever, and helping clinicians create long-lasting, esthetic restorations. Lawson adds. Meta-analysis of bonding effectiveness to zirconia ceramics. J Dent Res. Brown, Douglas.

BisDent Globe, ;14 1. A 5-year retrospective study of survival of zirconia single crowns fitted in a private clinical setting. J Dent. Lawson, NC Choice of cement for single-unit crowns.

Journal of the American Dental Association. Best practices for bonding with zirconia. January 24, Laura Dorr. Continue reading on the next page Understanding the bonding procedure Bonding with zirconia can be problematic; since the majority of bonding protocols are based on bonding to glass, which zirconia is not, different steps need to be followed.

Preparation and decontamination One of the biggest errors a clinician can make when bonding to zirconia is not preparing-and decontaminating-the crown adequately.

Sandblasting is the way to prepping zirconia; etching does not work. And more importantly: phosphoric acid grabs and blocks the oxide groups needed for bonding.

You might remember the discussion of phosphate groups from Myth 1 when we explored how those interact with the oxide groups in zirconia and end up grabbing on to the bonding interface. Alec Ganci does a nice job of explaining bonding to zirconia in this Dental Economics article. The bottom line is that zirconia will attract phosphate groups, which ruin the bonding surface. You already need to be conscious of any saliva contaminating the restoration, and adding in Phosphoric Acid which, yes, is full of phosphate groups will seriously compromise the clinical outcome of your zirconia restoration.

There is a reason why not all zirconias are alike! Composition, grain size, shape of the zirconia particles, type and amount of the stabilizing oxides like yttria content which determine crystal phases and the processing are all factors that can vary in dental zirconia.

A 3Y-TZP is going to be strong, but less translucent. A 5Y-TZP is not going to be as strong but will be more translucent because it has more cubic phase polycrystals. A 4Y-TZP is going to have a very balanced blend of strength and translucency. To further explore the variations of zirconia, download this whitepaper. When it comes to dental materials, trusting in the science is the surest path to clear understanding.

In the recipe for restorative success, you need the right ingredients — and that means monomers that work together to…. You have a lot of options to treat missing teeth — but what about cemented implant restorations? Zirconia exhibits mechanical properties comparable with those of metal dental materials, has a color similar to that of teeth, and has several physical and biocompatible advantages [ 1 ].

Many studies investigating adhesion with zirconia have been performed, and some adhesion enhancement has been confirmed using several different surface treatments. Examples of such surface treatments for zirconia include airborne-particle abrasion AB [ 2 — 4 ], silica coating [ 5 , 6 ], selective infiltration etching [ 7 ], and laser etching [ 5 , 6 ], among others. However, other studies have reported limitations in such methods.

For instance, silica coatings are reportedly insufficient for long-term stability due to the hydrolytic degradation of silica coatings [ 8 , 9 ]. Selective infiltration etching has a couple of clinical problems, including its complexity and the high costs that are associated with the application process. Laser etching is also reportedly less efficient at altering the surface of zirconia than is AB, exhibits lower adhesive strength when dental resin cements are applied, and causes phase transformation into the excessive monoclinic phase [ 10 , 11 ].

It is expected that if AB and methacryloyloxydecyl dihydrogen phosphate- MDP- containing luting agents are used adequately for cementing zirconia, then this will yield successful long-term clinical bonding [ 12 — 16 ].

However, it has also been suggested that the surface roughness of zirconia varies according to the particle size, distance, and duration of AB, which are manual processes and may affect the bonding strength of the resin adhesive [ 17 ].

In addition, a few studies have reported a decrease in the physical strength of zirconia depending on the flaws caused by AB [ 18 — 20 ]. Recently, studies examining the efficacy of employing chemical etching as a surface treatment for zirconia have been published [ 21 , 22 ]. Especially, hydrofluoric acid has been reported to be useful for surface treatment of zirconia and resin cement bonding [ 23 — 25 ]. However, extensive investigations of this approach are lacking still.

Accordingly, the aim of the present study was to investigate changes in the microstructure and phase transformation of zirconia surfaces using etching and AB, and in each case, it was determined whether it affected the shear bond strength of dental resin cements to zirconia.

The null hypothesis was that a strong-acid solution would not be able to appropriately etch the zirconia surface for improving the shear bond strength of dental resin cements to zirconia. These four groups were then classified into two subgroups each according to the resin cement used for bonding, i. A total of 8 groups were designated according to the zirconia surface treatment method and the resin cement used for bonding zirconia and the composite resin block.

A total of 88 specimens were fabricated Table 1 , with 11 specimens per group for the shear bond strength testing. It has recently been reported that strong acid can be used to alter the surface of zirconia [ 21 , 23 — 26 ].

In this study, the fabrication and application of strong acids were devised based on the results of previous studies investigating the etching of zirconia. Alternatively, after applying Clearfil ceramic primer Kuraray in the same manner, adhesion was performed using Panavia F 2. The cementation jig was made from putty 3M ESPE , and resin blocks were bonded to the center of the zirconia block using the cementation jig Figure 1. Immediately after the artificial aging process, the shear bond strength was measured using a universal testing device Instron ; Instron Corporation, Seoul, Korea with a crosshead speed of 0.

The zirconia surfaces were assessed using a scanning electron microscope Hitachi SN; Hitachi Co. The adhesion failure mode of the zirconia surface was assessed at a magnification of 40x. X-ray diffraction XRD experiments were performed to investigate the phase transformation of zirconia surface particles following the surface treatments. For this purpose, eight zirconia disks 1. One untreated disk and seven disks from each of the surface treatments were observed and analyzed.

For the comparison of the shear bond strengths, one-way analyses of variance with the Dunnett T3 validation method were performed using PASW version Differences were considered statistically significant at. The mean and standard deviation of the shear bond strength between the dental resin cement and zirconia according to the surface treatment method are summarized in Table 3.

According to the results of our analyses of variance, the shear bond strengths were different according to the zirconia surface treatment for both cements Table 3. When Panavia F 2. Our SEM evaluations revealed that the surface roughness of the zirconia was greater when the surface was treated with etching and AB than it was when zirconia did not undergo surface treatment.

The appearances of the etched and airborne-particle-abraded surfaces were different from each other. And the irregularity of the etched surface was more uniform than that of the AB surface at 2,x magnification Figure 2.

After the shear bond strength testing of the dental resin cements to zirconia, the zirconia surface was observed at 40x magnification using SEM Figure 3. According to the results of this study Table 3 , the null hypothesis stating that zirconia surfaces cannot be appropriately etched using strong-acid solutions for improving the shear bond strength of dental resin cements to zirconia was rejected. The etching process involves chemically dissolving particles on the zirconia surface by applying a strong acid, which may be advantageous because it permits a more-objective application and yields more-consistent results than AB.

Similar to previous studies, our SEM images confirmed that morphological changes occurred on the surface of zirconia following etching with a strongly acidic solution. The surface irregularities of samples that were etched with acid were more uniform and detailed than those in the samples that were treated with AB alone Figure 2. In addition, the surfaces of ET30 samples were over-etched compared with those of ET15 samples, and the surface roughness of ET30 samples was lower than that of ET15 samples, likely leading to the lower shear bond strength of the ET30 vs.

ET15 group. The shear bond strength of the AB group in the present study was rather low compared to that reported in other studies [ 3 , 4 , 8 , 27 ]. This seemed to be due to the fact that the initial surface condition of the zirconia before surface treatment and the distance between the crosshead of Instron and zirconia surface was different from those of previous studies [ 28 ]. In previous experiments, zirconia in a semisintered state was cut into blocks of a specific shape using a diamond bur or milling machine, and the surfaces of the block for bonding were prepared using sandpaper processing; then, the block was fully sintered.

However, in clinical practice, it is believed that sandpaper could not be applied to the inner surface of the prosthesis for bonding, and thus, we thought that using computer numerical control milling would be more suitable for preparing the surface, as this approach is similar to that used in clinical situations.

However, methodological verification of this approach to surface preparation is necessary. It was speculated that the flexural strength of ABET zirconia may be enhanced by the transformation toughening [ 29 , 30 ]. The average shear bond strength of samples on which Rely-X U was used was higher than that of samples on which Panavia F 2. The authors speculated that this was because the self-adhesive cement penetrates more easily through gaps in the roughened surface to form microchemical interlocks and because the inorganic filler of the self-adhesive resin cement is more resistant to hydrolysis and plays an important role in cement formation.

Magne et al. There are some advantages of the etching of zirconia beyond more objectively and consistently increasing bond strength of cement. One-time procedure of etching zirconia with strong acid s can be used not only for bonding with resin cement but also for increasing the bonding strength with porcelain veneers at the same time, and there will be no need to perform airbone-particle abrasion in the clinic before cementation.

Within the limitations of the present study, the following conclusions were drawn: 1 strong-acid etching of zirconia caused significant surface changes that increased the shear bond strength of resin cement, and 2 the shear bond strength of resin cements was higher when zirconia was etched with strong acid than when AB was used alone.

The authors declare that there are no conflicts of interest regarding the publication of this paper. Special thanks are due to the research institute director Mr. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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