Abstract
Studies have reported challenges of debonding of dental zirconia crowns to from luting cement and prepared teeth. The aim of the study was to explore the application of dental glazing systems for enhancing the bonding of zirconia dental ceramics to luting resin cement. Commercial glaze powder and liquid (Vita Akzent) and experimental mica-based glaze powders were used for the study. X-ray diffraction analysis of the glaze powders (XRD) and Fourier Transform InfraRed Spectroscopy (FTIR) was done on the glaze liquid. Sandblasted sintered dental zirconia (Katana, Noritake) were the control samples. Glazed zirconia samples were coated with commercial glaze and experimental glaze powders which were further etched with 5% hydrofluoric acid. Shear bond strengths of sandblasted and glazed zirconia samples to resin composites were evaluated. XRD of commercial and experimental glaze powders revealed a broad peak confirming the amorphous nature of glass and FTIR analysis of the glaze liquid revealed symmetrical stretching (CH2-CH3) of the alcohol group indicating a mixture of iso-butane and ethanol. Glazed and etched zirconia showed significantly higher shear bond strength to resin cement compared to sand-blasted zirconia. The study confirms the glassy nature of dental glaze powders and the presence of ethanol-based mixtures in the commercial glaze liquid. Glazing systems have the potential to be explored for enhancing the bonding of non-etchable zirconia ceramics to resin cement and tooth substrates.
Keywords: Dental glazes, Dental zirconia, Mica-based glaze, Zirconia bonding, Zirconia ceramics, Ceramics, Dental Porcelain
1. Introduction
Dental ceramics are one of the most common dental restorative materials used for replacing missing teeth in the form of prosthetic crowns and bridges. Many studies have been pursued to improve dental ceramics’ cosmetic, mechanical, and physical properties. Zirconia dental crowns have been a popular dental restorative material due to their good mechanical properties and reasonable aesthetics. However, it has limitations of inadequate adhesive bonding due to the inability to etch its oxide surface unlike the etchable glass-ceramics [1,2]. Further, the bonding ability of zirconia crowns becomes much more critical when there is inadequate crown height [3,4]. In such conditions, mechanical and chemical retention methods were suggested to enhance the bonding ability of zirconia crowns to tooth substrate. The most common mechanical method had been sandblasting or air-abrasion with alumina particles. Chemical methods range from surface etching, tribochemical silica coating, and the use of ceramic primers such as MDP [5]. Laser treatment, micro-slit retention with laser beams, selective silica infiltration, and glazing followed by etching and silanization haves also been explored [6–8].
The mechanical method of sandblasting the intaglio surfaces of zirconia crowns creates stress concentrators through impact energies on zirconia and further can deteriorate its flexural strength. However, contradicting results of improved and low bond strength of zirconia crowns to resin cement have been reported. On the other hand, glaze-on techniques of zirconia crowns have been shown to be beneficial in improving their bond strength [7]. Glazing is a traditional technique of applying a glassy laminate on the external surface of bi-layered veneering ceramics or monolithic ceramic crowns. The thin glassy film is essentially formed due to viscous flow. The viscous flow occurs as glass fuses at high temperatures while sintering in the furnace. Glazing of dental ceramic crowns is typically done to heal the inherent pores occurring on the fired porcelain’s external surface, to obtain a smooth surface, and simulate natural tooth surfaces [9]. The composition of dental ceramic glaze consists of silica, porcelain, glass–ceramics or heavy crystalline solids. It is available in the form of powder and liquid, as shown in Fig. 1 or as a spray or paste [10–12]. Various commercial dental glazes are available presently in the dental market such as Vita Akzent, IPS e.max Ceram glaze, and ICE ZirkonZahn glaze, shown in Table 1. Other than glass-based glazes, a glass–ceramic glaze containing fluorapatite crystals was synthesized [13].
Fig. 1. Vita Akzent Glaze powder and liquid [12].
Table 1. Commercial dental glaze systems available in the market.
| Commercial Dental Glaze Systems | Form/Availability | Composition |
|---|---|---|
| IPS e.max Ceram Glaze | Powder/Paste/Spray | Ceramic (Safety Data Sheet) |
| IPS e.max Ceram Fluorescent Glaze | Paste | 60−70 % ceramic powder pigments 30−40 % glycol and glycerine |
| ICE ZirkohnZan ICE Stain Liquid | Powder & liquid | 60−70 w% ceramic powder and pigments 30−40 w% glycol |Ref| |
| Ceramco PFZ Overglaze, Ceramco PFZ Stain & Glaze Liquid | Powder & liquid | 60−70 w% ceramic powder and pigments 99 w% propylene glycol |
Several studies explored the use of dental glazes to enhance the bonding of zirconia ceramic crowns to tooth substrates. A newly developed experimental glaze material was applied to the intaglio surface of leucite glass-ceramics to facilitate etching for adhesive bonding in order to increase the flexural strength of leucite glass ceramics glass-ceramics. The AN experimental overglaze significantly improved the biaxial flexural strength of the leucite glass–ceramic substrate and produced comparable shear bond strengths to etched and bonded ceramics [14]. Zirconia dental crown restoration was coated with a novel multi-phase glaze to increase the bond strength between the zirconia crown and resin cement. The multi-phase glaze material consisted of lithium disilicate and lithium orthophosphate phases [15]. The addition of a glaze layer over zirconia improved the bond strength with silane/adhesive/Variolink II but found no effect with zirconia primer/Multilink Automix group [7]. Based on the above literature, an experimental mica–based glaze was processed that had a similar coefficient of thermal expansion of zirconia [16,17]. The aim of the study was is to explore the potential of experimental mica-based glazing systems to bond to zirconia ceramics. The objectives of the study are to characterize experimental mica-based glazes with commercial dental glazing systems (Vita Akzent) and investigate glazing as an effective bonding system to zirconia dental crowns.
2. Materials and methodology
Commercial dental glaze, Vita Akzent Plus, and experimental mica-based glaze powders were used in the present study. The experimental mica-based glaze was obtained from the melt-quench technique of a fluorosilicate-based glass frit (44.5 SiO2–16.7 Al2O3–9.5 K2O–14.5 MgO–8.5 B2O3–6.3F (wt. %)) [16,17]. Both the glaze powders were subject to the characterization of X-ray diffraction (XRD). Commercial liquid glaze Vita Akzent Plus was subject to Fourier Transform Infrared Spectroscopy analysis (FTIR). Sintered and milled zirconia samples were sandblasted and glazed with commercial and mica-based glazing systems and their shear bond strength to resin cement was further evaluated. The sintering protocol for the commercial Vita Akzent was followed according to the manufacturer’s instructions. A holding period of 20 min at 1200 °C in the furnace was followed for the experimental micabased glaze. The justification for the time and temperature of the experimental glaze was based on studies reporting on repeated heat treatment of feldspathic glazing cycles that did not influence the mechanical properties and the surface microhardness of zirconia. Minor transformation from the tetragonal to the monoclinic phase was observed on the surface of zirconia following feldspathic glazing, with beneficial compressive stresses on the surface of zirconia [18]. With this background, the above sintering protocol of a single glazing cycle for experimental mica-based glass was intended. The materials used in the present study are presented in Table 2.
Table 2. Materials and their commercial brand names used in the study.
| Materials | Commercial Brand Names |
|---|---|
| Commercial Glaze Powder | Vita Akzent |
| Commercial Glaze Liquid | Vita Akzent Plus |
| Zirconia Substrate | Katana, Kuraray, Noritake |
| Hydroflouric acid and silane | CeraEtch, Prevest DenPro |
| Dual cure resin cement | Paracore, Coltene |
| Bulk resin composite | Te-Economic Plus, Ivoclar Vivadent |
2.1. X-ray diffraction analysis
X-ray diffraction analysis of commercial glaze powder (Vita Akzent Plus) and experimental mica-based glaze powders was done using Bruker D8 ADVANCE X-ray Diffractometer, 2.2 kW X-ray source of Cu anode with fine focus ceramic x-ray tube operated at 40 kV Voltage and 40 mA current at 1.6 kW power. Data was collected using a PSD High-speed SSD160-2 detector with a 500 μm sensor.
2.2. Fourier transform infrared spectroscopy (FTIR)
FTIR of Vita Akzent glazing liquid was done using the Alpha Bruker instrument with attenuated total reflectance mode.
2.3. Sample preparation
Sintered and milled zirconia samples (Katana, Kuraray, Noritake) (n = 15) of dimensions 10X5X5 mm were polished and ultra-sonicated using ethanol for 10 min and further air-dried. Five samples (n = 5) of each group were for each of the interventions of sandblasting and glazing with commercial and experimental glazes, respectively.
2.3.1. Sandblasting zirconia samples
In order to differentiate the preferred surface for sandblasting, the unused surfaces of the samples were covered with adhesive tapes. The exposed surface of the zirconia samples (n = 5) was sandblasted using Al2O3 particles of 110 μm at a distance of 10 mm for 10 secs at an air pressure of 4 bar [15]. The samples were further ultrasonicated in ethanol and air-dried.
2.3.2. Vita Akzent glazing of zirconia samples
A thin uniform layer of a mixture of Vita Akzent plus powder and Vita Akzent glazing liquid was applied on the polished rectangular surfaces of sintered zirconia samples (n = 5) using the brush technique in unidirectional strokes according to manufacturer’s instructions. The samples were fired at an initial temperature of 400 °C for 4 min with an increase of temperature by 80 °C/min to the sintering temperature of 780 °C according to furnace program protocols. A holding time of 1 min at 780 °C was followed by gradual cooling of the samples to room temperature [19].
2.3.3. Experimental glazing of zirconia samples
A thin layer of experimental mica-based glaze mixed with Vita Akzent glazing liquid was applied over the polished surface of the zirconia samples (n = 5) using a brush technique in unidirectional strokes. Typically, glaze liquid consists of 70% ethyl alcohol with distilled water that is used to form a slurry with the glaze powder [19]. Therefore, the experimental mica-based glaze powder was mixed with the Vita Akzent liquid. The glazed samples were fired from room temperature (27 °C) with a heating rate of 25 °C/min to 1200 °C. A holding period of 20 min at 1200 °C in the furnace was followed and the samples were further cooled down to room temperature.
2.3.4. Etching and silanization of glazed zirconia samples
Glazed surfaces of each of the glazed zirconia samples of both commercial (Vita Akzent Plus) and experimental mica-based glaze groups were etched with 5% buffered hydrofluoric acid (CeraEtch, Prevest DenPro) for 90 sec, rinsed with water and air-dried. Further, 1–2 coats of Silane-X (CeraEtch, Prevest DenPro) were applied with a brush tip applicator to the etched surfaces and allowed to dry for 30 secs.
2.3.5. Bonding of zirconia samples to resin cement
The sandblasted and glazed surfaces of each of the groups were bonded with dual cure resin cement (Paracore, Coltene) as a thin coat for cementation to the dimensions of zirconia (10X10X5mm). The manufacturer’s instructions were followed for bonding and light curing with a light-emitting diode. The samples were further built with bulk resin composites (Te-Economic Plus, Ivoclar Vivadent) of in the same dimensions of zirconia (10X10X5 mm) for shear bond strength testing.
2.4. Shear bond strength test
Each of the groups of sandblasted and glazed samples was subject to shear bond strength testing using an Instron testing machine (Mecmesin, MultiTest 10-i, UK) with a load cell of 5000 N at a crosshead speed of 2 mm/min until failure. The samples were held perpendicular to a knife-edge chisel to apply the required load. The shear bond strength (SBS) was calculated by dividing the maximum force (N) by the bonding area (length X breadth of the samples).
2.5. Statistical analysis
Statistical Package for Social Sciences (SPSS, Windows Version 22.0 Released 2013. Armonk, NY: IBM Corp.) was used to perform statistical analysis. The results of shear bond strength were will be subject to ANOVA statistical tests to determine the differences between the zirconia groups with a significance level of p-value less than 0.05.
3. Results
The results of the X-ray diffraction analysis of commercial dental glaze and the experimental mica-based glaze powders are presented in Fig. 2 and Fig. 3, respectively. FTIR analysis of the Vita Akzent glazing liquid is shown in Fig. 3. The results of the shear bond strength test are presented in Table 3.
Fig. 2. X-ray diffraction pattern of add-on dental glaze powder (Vita Akzent Powder).
Fig. 3. X-ray diffraction pattern of experimental mica based dental glaze powder.
Table 3. Shear bond strength results of zirconia samples.
| Zirconia sample groups | Shear bond strength (MPa) | |
|---|---|---|
| Mean | S.D. | |
| Sandblasting (Control) | 1.35a | 0.73 |
| Commercial Glaze (Vita Akzent) | 4.48b | 1.14 |
| Experimental Mica Glaze | 2.8c | 0.81 |
Superscript mean statistically significant differences between the groups.
4. Discussion
The results of XRD and FTIR of commercial glazing systems, Vita Akzent, and experimental mica-based glaze will be discussed with the shear bond strength results of zirconia samples in the following paragraphs.
4.1. X-ray diffraction (Vita Akzent powder and experimental mica-based glaze powder)
The results of X-ray diffraction analysis reveal a hump confirming the amorphous nature of Vita Akzent and experimental mica-based glaze as shown in Fig. 2 and Fig. 3, respectively. Glass typically shows a broad hump in the XRD pattern compared to the sharp peaks seen in crystalline materials. The hump observed is due to the short-range order of atoms in the glass network [20].
4.2. FTIR analysis of glazing liquid (Vita Akzent Liquid)
The first peak of the plot in Fig. 4, at 643 represents C–C–C skeletal vibrations which range from 720 to 750 cm−1. The second peak at 1031 represents the C-O bond stretching ranging from 1075 to 1350 cm−1 The peak at 1452 in Fig. 4 confirms C–H deformation bending vibrations absorptions with a significant double peak ranging from 1470 to 1365. The peak at 2860, points to C–H stretching vibration, ranging from 2845 to 2975 for isobutane, the peak at 2929 depicts ethanol at 2850–3010 and the peak at 3319 depicts O–H vibrations ranging from 3230 to 3500. The symmetrical stretching (CH2-CH3) of the alcohol group is seen in Fig. 4. Based on the above interpretations, it could be deduced that Vita Akzent liquid has a mixture of isobutane and ethanol.
Fig. 4. FTIR spectrum of add-on dental glaze liquid (Vita Akzent).
4.3. Shear bond strength testing of zirconia samples
Statistically significant differences in shear bond strength values between the groups (p value = 0.00) with the commercially glazed zirconia samples showing the highest shear bond strength value followed by experimental mica-based glaze and sandblasted groups, respectively in Table 3. Commercial glaze Vita Akzent due to its glassy nature would have facilitated an effective etching with micro-mechanical retention compared to the experimental mica-based glaze. This would further require scanning electron microscopy analysis to substantiate the results with the etched surfaces of commercial and mica-based glazing systems on zirconia. The differences in the shear bond strength between commercial and experimental glazes in the present study could be due to the difference in their glass compositions, the occurrence of voids or spaces between the glazes and zirconia, and the possibility of thermal residual stresses across their interfaces. As reported in previous studies, the low shear bond strength of sandblasted zirconia samples could be corroborated by the insufficient micro-mechanical retention required for adhesive bonding [15]. The adhesive mode of failure was evident in sandblasted zirconia samples, while a cohesive mode of failure was observed in glazed zirconia samples. These observations further support the high shear bond strength of glazed zirconia compared to sandblasted zirconia samples. A number of commercial glazes have been applied on the intaglio surfaces of zirconia substrates to improve their bond strength as shown in Table 4. As can be seen from Table 3, studies on glazed zirconia showed high shear bond strength values compared to the values obtained from the present study [21-25]. Hydroxyapatite and multi-phase glass–ceramic glaze showed higher shear bond strength with zirconia ceramic substrates (Ntala, 2010). The addition of a glaze layer (ICE, ZirkonZahn glaze powder, and liquid) over zirconia improved the bond strength with silane/adhesive/Variolink II but found no effect with the zirconia primer/Multilink Automix group [7]. Other than zirconia ceramics, the experimental over-glaze was developed for application to the fit surface of leucite glass–ceramic restoration to facilitate adhesive bonding and increase the flexural strength of the ceramic substrate [14]. Vita Akzent glaze used with 9% hydrofluoric acid showed a higher shear bond strength value compared to the results of the present study, with 5% hydrofluoric acid [24]. This variance in the shear bond strength values across the studies in Table 4, could be due to different brands of zirconia, resin cement, the concentration of hydrofluoric acid etchants, and glazes used. Limitations of the study are the narrow sample size and the design of the Schmitz-Schulmeyer method for the shear bond strength test could have been followed to hold the zirconia substrate [23]. Glazing of experimental mica-based at temperatures below 1200 °C and its effect on phase transformation, microstructural analysis of dental zirconia, and shear bond strength can be further investigated in the future.
Table 4. Shear bond strength values of glaze-on technique on zirconia for bonding to resin cement.
| Author (Year) | Glaze | Ceramic Substrate | Resin Cement | Bond Strength (MPa) |
|---|---|---|---|---|
| Cheung (2014) | Pre-fired overglaze (Cercon Ceram Kiss) | Zirconia (Cercon) | Panavia F 2.0 | 17.3 ± 1.7 |
| Paste liner | 18 ± 2.6 | |||
| Sandblasting | 3.9 ± 0.7 | |||
| Vanderlei (2014) | Vita Glaze Spray with 9% HF acid | Zirconia (VITA InCeram) | Panavia F 2.0 | 13.3 ± 4.1 |
| Vita Akzent with 9% HF | 9.3 ± 2.7 | |||
| Without surface conditioning | 0.01 ± 0.0 | |||
| Ntala (2010) | Experimental 10 wt% of Hydroxyapatite | Zirconia (Kavo) | Variolink II | 5.6 ± 1.7 |
| 20 wt% Empress glass-ceramic/glaze | 11 ± 3 | |||
| Everson (2011) | Vitadur Alpha with 10% HF | Zirconia (3 M Lava) | Z100 resin based composites | ~ 25 |
| Emax Ceram | ~ 22 | |||
| Noritake Cerabien | ~ 28 | |||
| Vita VM9 | ~ 18 | |||
| Lava Ceram | ~ 20 | |||
| Cura (2012) | ICE Glaze with silane | Zirconia (ICE Zirkon Zahn) | Variolink II | 9 ± 1.3 |
| ICE Glaze with silane | Zirconia primer | 4.9 ± 1.1 | ||
| Valentino (2012) | Cercon Ceram Kiss glaze with silane | Zirconia (Cercon) | Enforce | 25.7 ± 8.7 (Microshear) |
| Cattel (2009) | Experimental alumina-silicate glass powder | Leucite Glass Ceramic | Marathon-v | 9.8 ± 1.9 |
| Present study | Vita Akzent with 5% HF | Zirconia (Katana) | Paracore | 4.4 ± 1.1 |
| Mica-based glaze with 5% HF | 2.8 ± 0.81 | |||
| Sandblasted | 1.3 ± 0.75 |
HF is hydrofluoric acid and ~ SD was not placed due to the graphical representation.
5. Conclusions
The study confirms the glassy nature of commercial dental glaze powder. FTIR of dental glaze liquid reveals the presence of ethanol-based mixtures in the commercial glaze liquid. The glazing systems have shown the potential for enhancing the bonding of non-etchable zirconia ceramics with the resin cement and thus, the durability of zirconia crowns can be improved.
Acknowledgments
We thank Wellcome Trust DBT India Alliance for funding the project under Early Career Fellowship for Clinicians and Public Health with the grant number IA/CPHE/18/1/503943.
Footnotes
CRediT authorship contribution statement
Kumar Sarthak: Investigation, Methodology, Writing – original draft. Karina Singh: Investigation, Methodology, Writing – original draft. Kumari Bhavya: Investigation, Methodology, Writing – original draft. Sivaranjani Gali: Conceptualization, Supervision, Methodology, Writing – review & editing.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Data availability
No data was used for the research described in the article.
References
- [1].Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. J Prosthet Dent. 2003;89:268–274. doi: 10.1067/mpr.2003.50. [DOI] [PubMed] [Google Scholar]
- [2].Blatz MB, Sadan A, Arch GH, Lang BR. In-vitro evaluation of long-term bonding of Procera AllCeram alumina restorations with a modified resin luting agent. J Prosthet Dent. 2003;89:381–387. doi: 10.1067/mpr.2003.89. [DOI] [PubMed] [Google Scholar]
- [3].Thompson JY, et al. Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now? Dent Mater. 2011;27:71–82. doi: 10.1016/j.dental.2010.10.022. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [4].Mombeini M, Dibazar S, Gholizadeh S. Evaluation of shear bond strength of zirconia to composite resin using different adhesive systems. J Clin Exp Dent. 2019;11:e257. doi: 10.4317/jced.55428. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [5].Usumez A, et al. Bond strength of resin cement to zirconia ceramic with different surface treatments. Lasers Med Sci. 2013;28:259–266. doi: 10.1007/s10103-012-1136-x. [DOI] [PubMed] [Google Scholar]
- [6].Asadzadeh N, Ghorbanian F, Ahrary F, Rajati Haghi H, Karamad R, Yari A, et al. Bond strength of resin cement and glass ionomer to Nd: YAG laser-treated zirconia ceramics. J Prosthodont. 2019;28:e881–e885. doi: 10.1111/jopr.12651. [DOI] [PubMed] [Google Scholar]
- [7].Cura C, et al. Comparison of alternative adhesive cementation concepts for zirconia ceramic: glaze layer vs zirconia primer. J Adhesiv Dent. 2012;14(1):75. doi: 10.3290/j.jad.a21493. [DOI] [PubMed] [Google Scholar]
- [8].Iwaguro S, et al. Effect of microslit retention on the bond strength of zirconia to dental materials. Dent Mater J. 2019;38(6):1043–1052. doi: 10.4012/dmj.2018-351. [DOI] [PubMed] [Google Scholar]
- [9].Al-Wahadni A, Martin DM. Glazing and finishing dental porcelain: a literature review. J Can Dent Assoc. 1998;64(8):580–583. [PubMed] [Google Scholar]
- [10].Craig JP, Ronald S. Book of Craig’s Restorative Dental Materials. 12th edition Elsevier; 2006. [Google Scholar]
- [11].Anusavice KJ. Phillip’s Science of Dental Materials. First South Asia edition. Elsevier; 2014. [Google Scholar]
- [12].VITA AKZENT® Plus - Optimizes everything. Effortlessly. ( vita-zahnfabrik.com)
- [13].Abolfathi G, Eftekhara YB. Synthesis of dental fluorapatite glass-ceramic glazes. Ceramics-Silikáty. 2011;55(4):394–400. [Google Scholar]
- [14].Cattell MJ, Chadwick TC, Knowles JC, Clarke RL. The development and testing of glaze materials for application to the fit surface of dental ceramic restorations. Dent Mater. 2009;25(4):431–441. doi: 10.1016/j.dental.2008.09.004. [DOI] [PubMed] [Google Scholar]
- [15].Ntala P, Chen X, Niggli J, Cattell M. Development and testing of multi-phase glazes for adhesive bonding to zirconia substrates. J Dent. 2010;38(10):773–781. doi: 10.1016/j.jdent.2010.06.008. [DOI] [PubMed] [Google Scholar]
- [16].Gali S, Ravikumar K, Murthy BVS, Basu B. Zirconia toughened mica glass ceramics for dental restorations. Dent Mater. 2018;34:e36–e45. doi: 10.1016/j.dental.2018.01.009. [DOI] [PubMed] [Google Scholar]
- [17].Macor - Wikipedia.
- [18].Hjerppe J, Fröberg K, Lassila LVJ, et al. The effect of heat treatment and feldspathic glazing on some mechanical properties of Zirconia. Silicon. 2010;2:171–178. doi: 10.1007/s12633-010-9042-y. [DOI] [Google Scholar]
- [19].Kumar NK, Nair A, Thomas PM, Hariprasad L, Brigit B, Merwade S, Shylaja V. Zirconia surface infiltration with low-fusing glass: A surface treatment modality to enhance the bond strength between zirconia and veneering ceramic. J Conserv Dent. 2022 Sep-Oct;25(5):492–497. doi: 10.4103/jcd.jcd_247_22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [20].X-Ray Diffraction (XRD) (iitk.ac.in)
- [21].Cheung Guy CK, et al. Effect of surface treatments of zirconia ceramics on the bond strength of resin cement. J Adhev Dent. 2014;16:49–56. doi: 10.3290/j.jad.a30753. [DOI] [PubMed] [Google Scholar]
- [22].Vanderlei A, et al. Evaluation of resin bond strength to yttria-stabilized tetragonal zirconia and framework marginal fit: comparison of different surface conditioning. Operat Dent. 2014;39–1:50–63. doi: 10.2341/12-269-L. [DOI] [PubMed] [Google Scholar]
- [23].Everson P, et al. Improved bonding of zirconia substructures to resin using a “glaze-on” technique. J Dent. 2012;40:347–351. doi: 10.1016/j.jdent.2011.12.011. [DOI] [PubMed] [Google Scholar]
- [24].Guess PC, Kulis A, Witkowski S, et al. Shear bond strengths between different zirconia cores and veneering ceramics and their susceptibility to thermocycling. Dent Mater. 2008;24(11):1556–1567. doi: 10.1016/j.dental.2008.03.028. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
No data was used for the research described in the article.