JJOD-2351; No. of Pages 8 journal of dentistry xxx (2014) xxx–xxx

Available online at www.sciencedirect.com

ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden

Comparison of fatigue resistance and failure modes between metal-ceramic and all-ceramic crowns by cyclic loading in water Maj H. Nicolaisen a,*, Golnosh Bahrami a, Scott Finlay b, Flemming Isidor a a Section of Prosthetic Dentistry, Department of Dentistry, Aarhus University, Vennelyst Boulevard 9, Aarhus, Denmark b Department of Oral Biology, School of Dentistry, University of Leeds, Clarendon Way, Leeds LS2 9LU, UK

article info

abstract

Article history:

Objectives: To compare fatigue resistance and fracture mode of metal-ceramic crowns with

Received 27 June 2014

all-ceramic crowns containing yttria tetragonal zirconia polycrystal (Y-TZP) frameworks

Received in revised form

under compressive cycling loading in water.

13 August 2014

Methods: Twenty specimens of ivory were randomized and individually prepared to receive

Accepted 21 August 2014

anatomically shaped metal-ceramic (n = 10) or veneered Y-TZP all-ceramic crowns (n = 10).

Available online xxx

All steps in production were equivalent to clinical situations. Resistance to fatigue fracture was tested under compressive cyclic loading using a universal testing machine, with a

Keywords:

loading frequency of 12 Hz using a spherical tungsten carbide indenter (6 mm diameter) in

CAD–CAM

distilled water. The maximum compressive load was increased as the number of cycles

Cyclic loading

increased (600,000 cycles at 400 N, 200,000 cycles at 600 N, 200,000 cycles at 800 N and

Dental material

200,000 cycles at 1000 N). The specimens were inspected after each loading sequence for

Fatigue test

initial failures such as infractions. Final failure was considered as any loss of material which

Metal-ceramic

automatically ended the test and the number of cycles until final failure was recorded.

Yttria-stabilized tetragonal zirconia

Fractographic analysis of the fractured specimens was performed with scanning electron

polycrystals ceramic

microscopy (SEM). Results: The two types of crowns exhibit similar fatigue resistance (P = 0.87) to compressive cycling loading under wet conditions. The failure modes as observed with SEM were similar in the two groups and were found in the veneer ceramic, except that three veneered Y-TZP all-ceramic crowns displayed a complete framework fracture. Conclusions: Within the limitation of this study using simulated oral masticatory function, the results revealed that the fatigue resistance was similar for the two crown types. Clinical significance: In this study metal-ceramic crowns and veneered Y-TZP all-ceramic crowns showed similar fracture resistance to compressive cycling loading in water. The test conditions were simulating clinical conditions. Thus, the result may predict the long-term clinical performance of these types of crowns. # 2014 Elsevier Ltd. All rights reserved.

* Corresponding author at: Section of Prosthetic Dentistry, Department of Dentistry, Aarhus University, Vennelyst Boulevard 9, DK-8000 Aarhus C, Denmark. Tel.:+45 20936369; fax: +45 86196029. E-mail addresses: [email protected], [email protected] (M.H. Nicolaisen), [email protected] (G. Bahrami), [email protected] (S. Finlay), [email protected] (F. Isidor). http://dx.doi.org/10.1016/j.jdent.2014.08.013 0300-5712/# 2014 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8

2

journal of dentistry xxx (2014) xxx–xxx

1.

Introduction

The increasing demand for aesthetically pleasing restoration of teeth, and concerns about metal containing restorations, have been the force behind the evolution of new materials and techniques, such as all-ceramic materials for crowns and fixed dental prostheses (FDPs).1,2 Metal-ceramic restorations have been used for more than four decades and are considered reliable.3,4 For many dentists this represents the gold standard for restoring teeth with single crowns and small gaps in the dental arch with FDPs.5,6 When replacing metal-ceramic restorations with all-ceramic systems, especially posteriorly in the mouth, a key aspect to consider is their susceptibility to fracture.7 Fractures are often preceded by the propagation of subcritical cracks in the material and this is accelerated in the presence of water.7,8 The propagating crack reduces the strength of the ceramic, leading to failure at occlusal loading which normally would not have been expected to induce failure.1 Fatigue degradation caused by cyclic loading enhances the water-assisted subcritical crack propagation.7–10 Clinical studies concerning metal-ceramic and veneered Y-TZP all-ceramic posterior crowns and FDPs are available.4,11–20 Some studies report an increased occurrence and severity of fractures of veneering ceramic with veneered Y-TZP all-ceramic restorations compared to metalceramic restorations, especially in the posterior areas.12,15,18,20 Yttria tetragonal zirconia polycrystal (Y-TZP) is a ceramic core material with excellent mechanical properties such as high toughness and strength.9 Stress induced phase-transformation of Y-TZP from the tetragonal crystalline structure to the more voluminous monoclinic structure limits crack propagation and enhances the strength and toughness of Y-TZP ceramics.21 Y-TZP is the strongest and toughest of all dental ceramics and is widely used as framework material for posterior crowns and FDPs.9,22 The appearance of Y-TZP and metal frameworks is not aesthetically pleasing; consequently, both frameworks must be veneered with a more translucent ceramic to obtain the appearance of a natural tooth.7,22 The ceramic veneer is predisposed to chipping.7 Despite these clinical drawbacks, there has been an increase in the use of all-ceramic systems in the last two decades in the posterior region of the mouth, owing to significant improvement in their mechanical properties, especially the development of the Y-TZP framework material. Several previous in vitro studies have investigated the failure modes, failure origins and crack propagation of the veneer and framework material separately, thus providing valuable information on the parameters for crack growth of the individual components of a crown or a FDP.23 However, lifetime prediction of a restoration requires a knowledge of the properties and behaviour when all components are assembled and treated as the finished restoration would be for clinically use. Studies on veneer-framework compositions can give information regarding failure mode, fracture origin and overall combined strength, which cannot be assessed by investigating the materials separately.23 Furthermore, crown-shaped test specimens cemented on preparations of tooth-like material10 may bring the test conditions even closer to the clinical situation.

Many in vitro tests have been based on static loading, where the loads that ultimately caused failure generated contact stresses much higher than those experienced in the oral cavity under occlusal loading, mastication and parafunctional behaviour.24 On the other hand, cyclic loading causes failure of the material at loads lower than static loading of the same material.25 Thus, fatigue tests with lower loads (using compressive cyclic loading) can prove more clinically relevant, since this test better imitates some of the stresses a material will be exposed to during a lifetime in function.7,8 Additionally, the aqueous environment of the mouth and cyclic loading during mastication are evidently favourable conditions for subcritical crack propagation in ceramic restorations.8 Thus, the evaluation of crack propagations and fracture behaviour in dental ceramics under such conditions is desirable. Consequently, the aim of this study was to compare the fatigue resistance and fracture mode of high-precious gold metal-ceramic crowns with veneered Y-TZP all-ceramic crowns when subjected to compressive cyclic loading in water.

2.

Materials and methods

2.1.

Specimen preparation

Twenty cylinders in the approximate size of a human molar (height 21 mm, diameter 9 mm) were cut from the same piece of elephant tusk. The ivory was kept moist in distilled water throughout the preparation and testing of the samples. Ten cylinders were randomized to receive metal-ceramic crowns and ten to receive veneered Y-TZP all-ceramic crowns with a CAD–CAM Y-TZP framework. Preparation was carried out by the same operator using standard approaches and following the manufacturer’s guidelines. A high-speed hand-piece with copious water irrigation and new diamond burrs were used for each preparation. The angle of convergence was 15o, namely 7.5o to the long axis of the cylinder. For the metal-ceramic crown preparations, a 1 mm shoulder was prepared on the facial aspect and a 0.6 mm deep chamfer on the remaining axial walls. The veneered Y-TZP all-ceramic crown preparations were made with a circumferential 0.8 mm deep chamfer. The height of the preparation was 4 mm on the walls representing the proximal surfaces and 5 mm on the walls representing the buccal and lingual surfaces (Fig. 1). The finish line was given a curvature similar to a molar crown preparation, with the finish line 1 mm more occlusally placed on the proximal surfaces than on the buccal and lingual surfaces. Impressions of the prepared specimens were made with a single-step, two-phase technique with silicone impression materials (Extrude, Kerr, KaVo Kerr Group, Romulus, MI, USA). The impression materials were mixed in accordance with the manufacturer’s instructions. The impressions were poured in stone (Nova Die Stone, BK Giulini, Ludwigshafen, Germany). The metal frameworks were cast from high noble Au–Pt alloy (BioPontoStar, BEGO, Bremen, Germany) using the lost wax technique. To facilitate the CAD–CAM fabrication of the Y-TZP frameworks, the stone dies of the veneered Y-TZP all-ceramic crown preparations were

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8 journal of dentistry xxx (2014) xxx–xxx

2.2.

Fig. 1 – Schematic drawing of the experimental set up to apply compressive cyclic loading to test specimens. (A) Loading column connected to an ElectroPulsTM E3000 universal testing machine (Instron) that was free to move in the transverse to loading direction. (B) Spherical indenter (Ø = 6 mm). (C) Metal-ceramic or veneered Y-TZP all-ceramic crown cemented onto (D) ivory preparation. (E) Embedding resin surrounding the ivory to aid installation into (F) specimen holder. (G) Distilled water at 36 W 1 8C.

scanned with a dental laboratory scanner (3Shape A/S, Copenhagen, Denmark). Fully anatomically shaped molar crowns were made using a manufacturing process similar to a clinical situation. The BEGO Medical Scan- und Designcenter (BEGO, Bremen, Germany) manufactured the Y-TZP frameworks. The Y-TZP frameworks were milled from presintered Y-TZP blocks (BeCe CAD Zirkon+, Bego, Bremen, Germany). Thickness of the metal–alloy and Y-TZP framework materials were both 0.5 mm. The crowns were veneered following the multi-layering/firing technique performed by hand layering by the same dental technician. The veneering ceramics VITA VM 13 and VITA VM 9 (VITA Zahnfabrik, Bad Sa¨ckingen, Germany) were used for the metal-ceramic and veneered Y-TZP all-ceramic crowns, respectively. The veneering ceramic had an overall thickness of 1–1.5 mm on the axial walls and 1.5–2.0 mm occlusally, as measured with an Ivanson Measuring Caliper at 10 points and additionally controlled with 2 digital radiographs (Digora1 Optime Imaging Plate, size 2/Digora Optime Plus, Soredex PaloDEx Group, Tuusula, Finland) for each crown, namely one in buccal–lingual direction and one in mesio-distal direction. The crowns were cemented on their respective ivory preparations using a resin-enhanced glass-ionomer cement (Ketac Cem+, 3M ESPE AG, Seefeld, Germany) using static finger pressure for 7 min, removal of excess cement and polishing the marginal area with a slow-speed rubber polisher. After 30 min, the samples were stored in distilled water at room temperature until fatigue testing. The storage time varied from 18 to 60 days before compressive cyclic loading. All materials were handled according to the manufacturer’s instructions.

3

Fatigue testing

Resistance to fatigue fracture was tested with compressive cyclic loading, thereby simulating accelerated mastication (Fig. 1). Following storage in distilled water the specimens were mounted in an embedding resin (Tecnovit 5071, Heraeus Kulzer GmbH, Wehrheim, Germany) to facilitate their attachment to the universal testing machine, leaving the crown and 2 mm apically of the marginal finish line free of the embedding resin. The crowns were subjected to compressive cyclic loading in a universal testing machine with a 5 kN load cell (Instron Electropuls E3000 Testing System, Instron Corp, Canton, Massachusetts, USA) using a Variable Angle Dental Implant Fixture (Instron) and a spherical tungsten carbide (KVJ A/S, Nykøbing F. Denmark) indenter (6 mm diameter) at a loading frequency of 12 Hz. The specimens were loaded uniaxially in line with the centre of the central fossa. Load was applied so that at least 3 cusps were loaded. The maximum compressive load increased as the number of cycles increased, namely 600,000 at 400 N, 200,000 at 600 N, 200,000 at 800 N and 200,000 at 1,000 N. Minimum compressive loading was 20 N during each loading series. The tripod balance of the indenter and cusps could be consistently reproduced to ensure the load was applied in the same location in each of the loading series. To prevent a spike in applied load at the initiation of each loading series, the stiffness of the specimen was measured and inputted into the controlling software of the testing machine, in addition to an envelope at the start of the waveform that gradually increased the peak load over 0.2 s to the desired magnitude. During the loading cycles the samples were submerged in distilled water kept at 36  1 8C with a water circulator (Compenstat, Gallenskamp, London, UK). The testing machine was programmed to end the test and unload the sample if a change in the digital position increased beyond 0.50 mm indicating that a sudden change in surface level had occurred. Between each series of cycles the crowns were inspected in order to identify surface wear, localised crushing at impact sites, infractions, cracks, crack evolution, chippings and fractures. The water tank was drained, the crown surface was cleaned with alcohol and photographs were taken using a digital SLR camera (Nikon D80, Nikon Corporation, Tokyo, Japan) with a AF 90 mm f/2.8 macro lens (Tamron, Saitama City, Japan) and a Metz 15 MS ring flash (Zirndorf, Germany). The criterion for the end of the test was either completion of 1.2  106 cycles or final failure of the test specimen. Final failure was designated as any chipping of the surface veneering or fracture of veneering and/or framework. Infractions or surface wear was designated as initial failure. The number of cycles to final failure along with failure location and mode were recorded for each specimen.

2.3.

Secondary electron imaging (SEM)

After cyclic testing, the samples were carefully cleaned with alcohol and dehydrated in a desiccator for 24 h; then mounted on aluminium stubs with double-sided adhesive carbon tape and silver paint. They were gold sputtered (Agar Auto Sputter Coater, Stansted, UK) to provide a conducting surface layer

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8

4

journal of dentistry xxx (2014) xxx–xxx

6 nm thick, thus preparing them for scanning electron microscopy (SEM). Secondary electron imaging was performed using SEM taken at an accelerating voltage of 15–20 kV and 50 mA probe current, on a Hitachi S3400N (Hitachi HighTechnologies, Tokyo, Japan) variable pressure SEM with either the secondary electron or back scattered detectors using the native software. Quantitative fractographic analysis was performed following the recommendations in a NIST recommended practice guide for fractography of ceramics and glasses.26

2.4.

Statistical analyses

Statistical difference in number of loading cycles to failure between the two groups was analysed by t-test. Differences in the initial failures (infractions) after 600,000 loading cycles were analysed with a Fisher Exact Test. Life tables were developed with the Kaplan–Meier Survival Analysis and survival curves were derived from life table analysis. The significance level was set to 0.05. The computer-programme package SigmaPlot 11 (Systat Software, San Jose, CA, USA) was used for the statistical analyses.

3.

Fig. 2 – Kaplan–Meier survival curve for metal-ceramic (MC) and veneered Y-TZP all-ceramic (AC) crowns. The maximum compressive load increased as the number of cycles increased, namely 600,000 at 400 N, 200,000 at 600 N, 200,000 at 800 N and 200,000 at 1,000 N. The symbols *, ~ and & denote cohesive failure, adhesive failure and framework fracture, respectively.

Results

3.1. Fatigue testing and failure modality of the metalceramic and veneered Y-TZP all-ceramic crowns All crowns failed before 1.2  106 cycles of the increasing loading regimen. The mean number of loading cycles leading to the final failure, fracture of veneering ceramic or framework, for metal-ceramic (X¯  SD; 772,746  133,024) and veneered Y-TZP all-ceramic (785,279  202,468) crowns was similar and the difference was not statistically significant ( p = 0.87). Furthermore, the log-rank test statistics for the survival curves did not reveal a statistically significant difference (Fig. 2). After the first sequence of loading (600,000 loading cycles at 400 N) surface damage such as localized crushing at the indenter impact site was evident on all specimens in both groups. Furthermore, infractions were seen on all of the veneered Y-TZP all-ceramic crowns, but only on four metalceramic crowns (Fig. 3A). This difference was statistically significant ( p = 0.01). In the metal-ceramic group five crowns failed cohesively (Figs. 2 and 3B) and five crowns failed adhesively (Fig. 3C). No metal-ceramic crowns showed framework fractures. Threeveneered Y-TZP all-ceramic crowns failed with a complete framework fracture, where two frameworks fractured in two equally sized pieces and one failed in three pieces (Fig. 3D). All framework failures occurred between 800,000 and 1,000,000 cycles. Aside from these three framework failures, three adhesive failures and four cohesive failures were found.

3.2. Secondary electron imaging of the fractured specimens (SEM) The findings from the visual inspection were verified by SEM and the failures modes as observed with SEM were similar in

the two groups. The crack origin in the veneer ceramic was located at the point of contact of the indenter during cyclic loading (Fig. 4A). In this zone, radiating cone cracks, regions with hackles (Fig. 4B) and arrest lines (Fig. 4C) were observed, indicating the direction of crack propagation. Furthermore, a compression curl (Fig. 4D) was observed in all specimens most distantly from the point of contact of the indenter. In other words, crack propagation started from the surface of the veneer and propagated towards the interface between the veneer and framework material and then deflecting towards the surface. A mirror at crack origin was not evident on any of the specimens due to localized crushing at the point of contact (Fig. 4A). Some of the fractures remained solely in the bulk of the veneer ceramic, while others reached the framework, as observed macroscopically. For the three veneered Y-TZP all-ceramic crowns with fracture of the framework, flaws were detected on the inner surface of the occlusal part of the framework and compression curls were observed on the outer surface at the corner between the occlusal and axial walls. Therefore, it is reasonable to assume that the origin of the crack was on the inner surface and in relation to a flaw.

4.

Discussion

In the present study, no significant difference in the number of compressive loading cycles leading to failure was observed between veneered Y-TZP all-ceramic and cast high-precious gold alloy metal-ceramic molar-like crowns. Similar to our study, comparable fracture strength of the veneer ceramic on veneered Y-TZP all-ceramic and metal-ceramic crowns has been observed in a study by Silva et al.27 when the Y-TZP frameworks were anatomically contoured. On the other hand, with an even thickness of the Y-TZP framework (as per conventional design) significantly lower fracture strength was

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8 journal of dentistry xxx (2014) xxx–xxx

5

Fig. 3 – Photographs of four molar-like crowns cemented on preparations of ivory. (A) Metal-ceramic crown with an initial failure (infraction) after 600,000 compressive loading cycles. (B) Veneered Y-TZP all-ceramic crown with a cohesive fracture (framework not exposed). (C) Metal-ceramic crown with an adhesive fracture (exposed framework). (D) Veneered Y-TZP allceramic crown with a complete framework fracture.

noticed. In the above-mentioned study27 the failures were mostly chipping of veneer ceramics as were also in this study. These results, therefore, indicate that the risk of veneer chipping of veneered Y-TZP all-ceramic crowns is related to the design of the framework. In contrast, it has been reported that the flexural strength is significantly higher for metal-ceramic than veneered Y-TZP all-ceramic when testing on rectangular test specimens28 and a similar result was also observed concerning the shear bond strength between veneer and framework material of cylindrical specimens. The differences between these results compared to our findings and those of Silva et al.27 may be explained by factors such as differences in applied load and shape of test specimens. Due to the complex geometry of molar-like crowns, mere changes in the contour of the framework of veneered Y-TZP all-ceramic crowns, as shown by Silva et al.27 can change the fracture strength significantly. Flaws in the materials related to the manufacturing process can act as the initiating point for a failure of the ceramic

restoration in clinical use.7 They can be related to the pressing of the material or from incorrect handling in the manufacturing process by the technician or by the dentist at try-in, occlusal adjustment or cementation.7 Another important aspect influencing the strength of the veneering ceramic is the relative coefficient of thermal expansion of the veneering material and the framework material. Consequently, it is important that these properties are taken into account and their application adjusted accordingly.7,29 In this study, after 600,000 compressive loading cycles at 400 N the specimens were inspected and significantly more veneered Y-TZP all-ceramic crowns were found with infractions in the veneer ceramic than metal-ceramic crowns. Since the survival analysis and the mean number of loading cycles to final failure were similar for the two groups, this difference in number of crowns exhibiting early failures (such as infractions) seems not to have bearing on the final failure, fracture of veneer ceramic or framework. For the metal-ceramic crowns all failures were chipping of the veneer ceramic. In contrast,

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8

6

journal of dentistry xxx (2014) xxx–xxx

Fig. 4 – Four SEM micrographs representing various fractographic features in the veneer ceramic. (A) SEM of the crack origin in the veneer ceramic located at the point of contact of the indenter and also radiating cone cracks. (B) SEM of a region with hackle. (C) SEM of arrest lines. (D) SEM of a compression curl. The magnification is given on the individual image.

three of the final failures in the veneered Y-TZP all-ceramic crown group were of a more catastrophic failure mode with a complete fracture of the framework and, consequently, also the veneer. The present study showed that the starting point of fractures in the veneer ceramic was caused by crushing at the indenter impact site for both types of crowns. This finding has also been observed previously.27 The hard contact generated by the tungsten carbide indenter would produce a higher stress concentration and potentially lead to a failure mechanism different from that of a clinical situation where enamel or porcelain would be the opposing material.10,24 However, cyclic loading with a tungsten carbide indenter of similar size has shown to reproduce clinically relevant fractures.27,30–32In previous studies, SEM analyses have indicated that the crack propagation in the veneer material starts in the area of occlusal loading.7,27,30 A similar finding was observed in this study. In contrast, the fractures of the Y-TZP frameworks in this study seem to start at flaws on the inner (cementation) surface of the occlusal part of the framework, as also observed in other laboratory studies28 and in studies dealing with clinical failures of alumina frameworks.33,34 Y-TZP as a framework material has been considered a possible substitute for metal-alloys due to its superior mechanical properties. However, chipping of the veneering ceramic is a common concern mentioned in clinical studies on veneered Y-TZP all-ceramic crowns and FDPs.12,15,18,20 On the other hand, based on the result from the present in vitro study,

veneered Y-TZP all-ceramic crowns with an anatomical contoured Y-TZP framework can endure fatigue loading just as well as metal-ceramic crowns. Different kinds of laboratory tests are widely used to test the strength of ceramic systems for dental restorations, such as three and four point bending tests as well as static, dynamic, and cyclic loading.1,22,24 Since these tests never reproduce the clinical situation completely, clinicians must bear in mind that such studies may provide useful initial information for selecting ceramic materials and techniques, but they do not directly predict the long-term clinical performance of crowns or FDPs.22 For this purpose welldesigned clinical studies are needed. On the other hand, the clinical failures of ceramic restorations are complex and involve both patient and material related variables.22 A controlled laboratory study can eliminate the inter-subject variables that are inherent in a clinical trial. Therefore, a combination of laboratory and clinical studies may yield the most comprehensive information. All specimens in our study were tested under conditions selected to simulate oral masticatory function, and the fracture mode observed was in many aspects similar to what is observed in the clinic. In contrast to the clinical situation, all failures started with crushing of veneer material in the area of contact with the indenter during loading. This difference may be explained by the hardness of the tungsten carbide indenter and the size of the contact area being different than opposing occlusal surfaces during function. Furthermore, the set-up in this study with the crown

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

JJOD-2351; No. of Pages 8 journal of dentistry xxx (2014) xxx–xxx

specimens loaded vertically and uniaxially at the center of the occlusal surface does not accurately simulate the direction of forces that can be generated during masticatory function or during parafunctional behavior. The direction, location and type of applied force can alter the resulting survival time and failure mode.

12.

13.

5.

Conclusions

Within the limitations of this in vitro study, metal-ceramic crowns with high noble gold alloy frameworks and veneered Y-TZP all-ceramic crowns with Y-TZP frameworks exhibit similar fatigue resistance to compressive cycling loading under wet conditions.

14.

15.

16.

Conflict of interest The authors declare no conflicts of interest to declare.

Acknowledgement

17.

18.

This study was partly funded by a grant from the Danish Dental Association FORSKU. 19.

references 20. 1. McLean JW, Hughes TH. The reinforcement of dental porcelain with ceramic oxides. British Dental Journal 1965;119:251–67. 2. Raigrodski AJ. Contemporary materials and technologies for all-ceramic fixed partial dentures: a review of the literature. Journal of Prosthetic Dentistry 2004;92:557–62. 3. Al-Amleh B, Lyons K, Swain M. Clinical trials in zirconia: a systematic review. Journal of Oral Rehabilitation 2010;37: 641–52. 4. Behr M, Winklhofer C, Schreier M, Zeman F, Kobeck C, Brauer I, Rosentritt M. Risk of chipping or facings failure of metal ceramic fixed partial prostheses — a retrospective data record analysis. Clinical Oral Investigations 2012;16: 401–5. 5. Rosenstiel SF, Land MF, Rashid RG. Dentists’ molar restoration choices and longevity: a web-based survey. Journal of Prosthetic Dentistry 2004;91:363–7. 6. Heintze SD, Rousson V. Survival of zirconia- and metalsupported fixed dental prostheses: a systematic review. International Journal of Prosthodontics 2010;23: 493–502. 7. Zhang Y, Sailer I, Lawn BR. Fatigue of dental ceramics. Journal of Dentistry 2013;41:1135–47. 8. Studart AR, Filser F, Kocher P, Gauckler LJ. In vitro lifetime of dental ceramics under cyclic loading in water. Biomaterials 2007;28:2695–705. 9. Denry I, Kelly JR. State of the art of zirconia for dental applications. Dental Materials 2008;24:299–307. 10. Kelly JR, Rungruanganunt P, Hunter B, Vailati F. Development of a clinically validated bulk failure test for ceramic crowns. Journal of Prosthetic Dentistry 2010;104: 228–38. 11. Walter M, Reppel PD, Boning K, Freesmeyer WB. Six-year follow-up of titanium and high-gold porcelain-fused-to-metal

21. 22.

23.

24.

25.

26. 27.

28.

29.

fixed partial dentures. Journal of Oral Rehabilitation 1999;26: 91–6. Sailer I, Gottnerb J, Kanelb S, Hammerle CH. Randomized controlled clinical trial of zirconia-ceramic and metalceramic posterior fixed dental prostheses: a 3-year followup. International Journal of Prosthodontics 2009;22: 553–60. Rinke S, Schafer S, Lange K, Gersdorff N, Roediger M. Practice-based clinical evaluation of metal-ceramic and zirconia molar crowns: 3-year results. Journal of Oral Rehabilitation 2013;40:228–37. Molin MK, Karlsson SL. Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs. International Journal of Prosthodontics 2008;21:223–7. Vult von SP, Carlson P, Nilner K. All-ceramic fixed partial dentures designed according to the DC-Zirkon technique. A 2-year clinical study. Journal of Oral Rehabilitation 2005;32:180–7. Crisp RJ, Cowan AJ, Lamb J, Thompson O, Tulloch N, Burke FJT. A clinical evaluation of all-ceramic bridges placed in patients attending UK general dental practices: three-year results. Dental Materials 2012;28:229–36. Schmitter M, Mussotter K, Rammelsberg P, Stober T, Ohlmann B, Gabbert O. Clinical performance of extended zirconia frameworks for fixed dental prostheses: two-year results. Journal of Oral Rehabilitation 2009;36:610–5. Sailer I, Feher A, Filser F, Gauckler LJ, Luthy H, Hammerle CH. Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. International Journal of Prosthodontics 2007;20:383–8. Beuer F, Edelhoff D, Gernet W, Sorensen JA. Three-year clinical prospective evaluation of zirconia-based posterior fixed dental prostheses (FDPs). Clinical Oral Investigations 2009;13:445–51. Raigrodski AJ, Yu A, Chiche GJ, Hochstedler JL, Mancl LA, Mohamed SE. Clinical efficacy of veneered zirconium dioxide-based posterior partial fixed dental prostheses: five-year results. Journal of Prosthetic Dentistry 2012;108: 214–22. Kelly JR. Dental ceramics: current thinking and trends. Dental Clinics of North America 2004;48:513–30. White SN, Miklus VG, McLaren EA, Lang LA, Caputo AA. Flexural strength of a layered zirconia and porcelain dental all-ceramic system. Journal of Prosthetic Dentistry 2005;94: 125–31. Studart AR, Filser F, Kocher P, Luthy H, Gauckler LJ. Cyclic fatigue in water of veneer-framework composites for all-ceramic dental bridges. Dental Materials 2007;23: 177–85. Kelly JR, Benetti P, Rungruanganunt P, Bona AD. The slippery slope: critical perspectives on in vitro research methodologies. Dental Materials 2012;28:41–51. Jung YG, Peterson IM, Kim DK, Lawn BR. Lifetime-limiting strength degradation from contact fatigue in dental ceramics. Journal of Dental Research 2000;79:722–31. Quinn GD. Guide to practice for fractography of ceramics and glasses. NIST Special Publication SP 960-16. 2007. Silva NRFA, Bonfante EA, Rafferty BT, Zavanelli RA, Martins LL, Rekow ED, Thompson VP, Coehlo PG. Conventional and modified veneered zirconia vs. metalloceramic: fatigue and finite element analysis. Journal of Prosthodontics 2012;21: 433–9. Ashkanani HM, Raigrodski AJ, Flinn BD, Heindl H, Mancl LA. Flexural and shear strengths of ZrO2 and a high-noble alloy bonded to their corresponding porcelains. Journal of Prosthetic Dentistry 2008;100:274–84. Saito A, Komine F, Blatz MB, Matsumura H. A comparison of bond strength of layered veneering porcelains to zirconia and metal. Journal of Prosthetic Dentistry 2010;104:247–57.

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

7

JJOD-2351; No. of Pages 8

8

journal of dentistry xxx (2014) xxx–xxx

30. Silva NRFA, Bonfante EA, Zavanelli RA, Thompson VP, Ferencz JL, Coelho PG. Reliability of metalloceramic and zirconia-based ceramic crowns. Journal of Dental Research 2010;89:1051–6. 31. Kim B, Zhang Y, Pines M, Thompson VP. Fracture of porcelain-veneered structures in fatigue. Journal of Dental Research 2007;86:142–6. 32. Schmitter M, Mueller D, Rues S. Chipping behaviour of all-ceramic crowns with zirconia framework and CAD/CAM

manufactured veneer. Journal of Dentistry 2012;40: 154–62. 33. Scherrer SS, Quinn GD, Quinn JB. Fractographic failure analysis of a Procera AllCeram crown using stereo and scanning electron microscopy. Dental Materials 2008;24:1107–13. 34. Oilo M, Gjerdet NR. Fractographic analyses of all-ceramic crowns: a study of 27 clinically fractured crowns. Dental Materials 2013;29:78–84.

Please cite this article in press as: Nicolaisen MH, et al. Comparison of fatigue resistance and failure modes between metal-ceramic and allceramic crowns by cyclic loading in water. Journal of Dentistry (2014), http://dx.doi.org/10.1016/j.jdent.2014.08.013

Comparison of fatigue resistance and failure modes between metal-ceramic and all-ceramic crowns by cyclic loading in water.

To compare fatigue resistance and fracture mode of metal-ceramic crowns with all-ceramic crowns containing yttria tetragonal zirconia polycrystal (Y-T...
1MB Sizes 0 Downloads 5 Views