In Vitro Fatigue and Fracture Load of Monolithic Ceramic Crowns Supported by Hybrid Abutment

In Vitro Fatigue and Fracture Load of Monolithic Ceramic Crowns Supported by Hybrid Abutment

The Open Dentistry Journal 22 Dec 2021 RESEARCH ARTICLE DOI: 10.2174/1874210602115010664



This study evaluated the performance of zirconia and lithium disilicate crowns supported by implants or cemented to epoxy resin dies.


Eigthy zirconia and lithium disilicate crowns each were prepared and assigned in four groups according to the crown material and supporting structure combinations (implant-supported zirconia, die-supported zirconia, implant-supported lithium disilicate, and die-supported lithium disilicate). Ten crowns in each group acted as control while the rest (n=10) underwent thermocycling and fatigue with 100 N loading force for 1.5 million cycles. Specimens were then loaded to fracture in a universal testing machine. Data were analysed using one-way ANOVA and Tukey multiple comparison test with a 95% level of significance.


No implants or crown failure occurred during fatigue. The mean fracture load values (control, fatigued) in newton were as follows: (4054, 3344) for implant-supported zirconia, (3783, 3477) for die-supported zirconia, (2506, 2207) for implant-supported lithium disilicate, and (2159, 1806) for die-supported lithium disilicate. Comparing the control with the corresponding fatigued subgroup showed a significantly higher fracture load mean of the control group in all cases. Zirconia showed a significantly higher fracture load mean than lithium disilicate (P=0.001, P<0.001). However, comparing crowns made from the same material according to the supporting structure showed no significant difference (P=0.923, P=0.337).


Zirconia and lithium disilicate posterior crowns have adequate fatigue and fracture resistance required for posterior crowns. However, when heavy fatigue forces are expected, zirconia material is preferable over lithium disilicate. Zirconia and lithium disilicate implant-supported crowns cemented to hybrid abutments should have satisfactory clinical performance.

Keywords: Chewing simulation, Fatigue, Fracture resistance, Lithium disilicate, Zirconia, Hybrid abutment, Dental implant.


Recent developments in computer-aided design/computer-aided manufacturing (CAD/CAD) have led to the introduction of all-ceramic restorative systems with increased strength, reliability, and aesthetic capabilities [1-3]. The earliest introduced alternatives, such as In-Ceram or Dicor, did not achieve the expected success because of inadequate mechanical properties, unacceptable fitting, or impractical manufacturing processes [4-7]. However, zirconia (Zr) and lithium disilicate (LD) ceramics are materials with desirable properties [8-12].

Currently, both LD and Zr ceramics are used to fabricate monolithic posterior restorations. A study [13] conducted in 2015 reported that monolithic Zr was the most prescribed material for posterior single crowns (32%) while LD was the top choice for anterior single crowns (54%). These preferences are obviously linked to the mechanical properties of Zr and the aesthetic properties of LD. The same survey [13] found that more aesthetically attractive choices such as PFM (31%) and LD (21%) were prescribed for posterior single crowns in high percentages. Lately, the concept of the aesthetic zone has changed, and the demand for highly aesthetic restorations even in the posterior region is evident in the rise of the use of composites in restoring posterior teeth [14] and the development of advanced all-ceramic materials that can withstand heavy occlusal loads in the posterior region. Therefore, the use of more aesthetically pleasing ceramics in the posterior region such as LD and more recently introduced zirconia reinforced lithium silicate (ZLS) restorations is expected.

Considering the present trend toward more conservative dental rehabilitation [15, 16], treatment of a missing tooth with an implant-supported single crown rather than a fixed partial denture should be a more rational treatment option [17, 18]. Implant-supported single crowns showed high survival rates [19, 20]. In addition, the results of a recent systematic review [20] found that the survival of implant-supported single crowns (93% after 5 years and 94.4% after 10 years) were higher than that of tooth‐supported all‐ceramic FPDs (86%–90%) [21], which is considered the traditional treatment option for a single tooth replacement. Although the decision of replacing a missing tooth with an implant crown can be the most reliable and conservative treatment modality, many factors can influence this decision, and in many cases, the relatively high cost of implant treatment is considered a major determinant regardless of oral health status and patient preference [22].

The application of hybrid abutment design using zirconia abutments is expected to provide both strength and aesthetics combined. However, few previous laboratory studies investigated the fracture resistance of ceramic crowns supported by hybrid abutment [23-26]. This study aimed at investigating fatigue survival and fracture load of monolithic Zr and LD crowns when supported by implants or cemented to epoxy resin dies. The study also investigated the in vitro fatigue performance of the hybrid abutment system composed of the all-ceramic crown, all-ceramic abutment and, Ti-Base. This study proposed two hypotheses:

  • Survival and fracture resistance of Zr and LD are not significantly affected by chewing simulation (1.5 million cycles) in thermocycled water.
  • Fracture resistance of implant-supported crowns is not significantly different from that of crowns cemented to epoxy resin dies within the same ceramic material groups.


A total of 80 crowns were prepared for this study and assigned to four major groups according to crown material and supporting structure combinations

  • Zr crowns supported by implants (n=20)
  • Zr crowns cemented to epoxy resin dies (n=20)
  • LD crowns supported by implants (n=20)
  • LD crowns cemented to epoxy resin dies (n=20)

2.1. Implants and Tooth Preparation

For the implant-supported crowns, 40 implants (Ankylos; Dentsply, Mannheim, Germany), Titanium Base (Ti-Base) abutments (Dess; Dental Smart Solutions, Montcada, Spain) with hex screw were used. Half the implants were used with monolithic Zr, and the other half were used with monolithic LD crowns, with all being fabricated using CAD/CAM technology.

For the crowns cemented to epoxy resin dies, a typodont model (A25A; Nissin Dental Products, Kyoto, Japan) of the mandibular first molar was prepared by an experienced prosthodontist according to the preparation guidelines for all-ceramic crowns to achieve 1.5 mm occlusal reduction, 1.0 mm proximal and axial reduction and a 1 mm shoulder with rounded inner edges. Vinyl polysiloxane impression (Imprint; 3M ESPE, MN, USA) of the prepared tooth model was repeated 40 times and poured with epoxy resin material (Exakto-Form; Bredent, Senden, Germany), resulting in 40 replicas of the prepared master die.

At this stage, the implants and epoxy resin dies were prepared and embedded in an acrylic resin base to fit the specimens’ holders of the chewing simulator and the universal testing machine planned to be used for the fracture test. Therefore, the specimen’s holder of the chewing simulator was used to create acrylic resin bases of the implants, and the epoxy resin dies. These bases guaranteed a standardized location of all crowns in the chewing simulator during fatigue testing (Fig. 1).

Fig. (1). Implant and master die are fixed in a standardized position in the chewing simulator specimen’s cup, A: implant, B: master die, C: chewing simulation in thermocycled water.

2.2. Zr Abutments and Crowns Preparation

The Ankylos ScanBase was scanned (D1000; 3shape, Copenhagen, Denmark) to obtain the geometry of the Ti-Base required to design Zr abutments. Then, the monolithic Zr and LD crowns were designed with split-file technology. The crown was designed according to the manufacturer's recommendations for full-contour crowns with a circular thickness of 1.0 mm and an occlusal thickness of 1.5 mm. A 5-axis milling machine (Zenotec select; Wieland Dental, Lindenstraße, Germany) was used to produce Zr abutments (n=40) and Zr crowns (n=20) from pre-sintered Zr discs (Zenostar Zr; Wieland Dental, Lindenstraße, Germany). The LD crowns (IPS e.max CAD; Ivoclar Vivadent, Schaan, Liechtenstein)) were wet milled in a wet milling machine (Zenotec select hybrid; Wieland Dental, Lindenstraße, Germany). After the CAM process, Zr components were sintered, and LD crowns were crystallized in the recommended furnaces (Programat S1 and Programat EP 3010; Ivoclar Vivadent, Schaan, Liechtenstein) respectively. Afterward, the fitting accuracy of the abutments and monolithic crowns was confirmed, and all crowns were glazed as recommended by the manufacturer.

To construct the crowns supported by epoxy resin dies, the preparation was firstly scanned with a laboratory scanner (D1000; 3Shape, Copenhagen, Denmark). Crown was designed for full-contour crowns with 1.0 mm circular and 1.5 mm occlusal thickness corresponding to the tooth preparation applied on the typodont model. The CAD file was then sent to the dry milling machine (Zenostar Zr; Wieland Dental, Lindenstraße, Germany) to mill 20 Zr crowns and a wet milling machine (Zenotec select hybrid; Wieland Dental, Lindenstraße, Germany) to produce the LD crowns. Sintering, crystallization, and glazing were carried out according to the manufacturer's instructions in the recommended furnaces (Programat S1 and Programat EP 3010; Ivoclar Vivadent, Schaan, Liechtenstein) respectively.

2.3. Cementation

Ti-Base abutments were firstly screw tightened on the implants with a torque wrench driver (Hex Driver; Dentsply, Mannheim, Germany) to 20 N/cm, and before cementation of the different components of the implant system, a temporary restorative material was used to fill the Ti-Base access hole. Then, Zr abutment and Ti-Base were cemented using self-curing composite (Multilink Hybrid Abutment; Ivoclar Vivadent, Schaan, Liechtenstein), and crowns were adhesively luted to the zirconia abutments (Multilink Automix; Ivoclar Vivadent, Schaan, Liechtenstein). Similarly, crowns supported by epoxy resin replicas were luted to the corresponding dies using the same cementation material (Multilink Automix; Ivoclar Vivadent, Schaan, Liechtenstein). All specimens were stored in water at a constant temperature (37 °C) for 30 days until the commencement of testing.

2.4. Fatigue and Fracture Testing

In each group (n=20), 10 specimens represented the control group while the other 10 underwent fatigue by means of a chewing simulator (CS-4.8; SD Mechatronik, Feldkirchen-Westerham, Germany) for 1.5 million cycles. Fatigue testing protocol involved a loading force of 100 N applied by a 6 mm diameter spherical stainless steel indenter and 1.2 Hz loading frequency. The indenter start point was confirmed at 0.5 mm lingual to the distobuccal cusp tip using articulating paper. A single loading cycle consisted of contact between the indenter and the specimen, load application, a lingual slide for 0.3 mm while the load is applied [27, 28]. Then the indenter leaves with an opening distance of 2 mm. Thermal cycling in controlled thermocycling unit (CS-4.8; SD Mechatronik, Feldkirchen-Westerham, Germany) between 5 °C and 55 °C (dwell time: 60 s, pause time: 15 s) in distilled water was carried out throughout the testing.

Specimens were checked for failure at 20 × magnification (M125; Leica Microsystems, Wetzlar, Germany). Fracture test for all crowns; fatigued and control was then carried out in a universal testing machine (Model LRX; Lloyds Instrument, West Sussex, UK) with a load cell of 5 kN loading capacity and less than 0.005% load resolution. Specimens were adjusted at a standardized location in the universal testing machine to achieve three points of contact with the indenter. The contacts were identified at the triangular ridges of the mesiolingual, distolingual, and distobuccal cusps. Vertical load with an 8 mm diameter stainless steel indenter at 1 mm/min crosshead speed was applied on the crowns until failure. Forces required to fracture the crowns were recorded in Newton.

Statistical analysis of the fracture load data was carried out using a statistical software package (SPSS, Version 23.0; IBM Analytics, Armonk, NY, USA). Normal distribution of data was confirmed using the Shapiro-Wilk test. The data was described descriptively and then analysed using a one-way analysis of variance (ANOVA) and Tukey multiple comparison test. The level of significance applied for all statistical analyses was set at 95%.

The sample size was initially chosen according to previous similar studies [28-40], which indicated that the number of specimens in subgroups ranged from 7 to 15, with a sample size of ten specimens being the most commonly used [28, 33-37]. We also conducted a post hoc power analysis using GPower [41] to ensure that our study design had enough power to detect the effect of chewing simulation and the effect of different material and supporting structure combinations on the fracture load of the crowns. Power calculation determined that a sample size of eight specimens would provide a 95% chance of finding a significant difference between the corresponding groups at the 5% level. The effect size found (1.47) indicates a large difference effect [42]. Therefore, ten crowns in each subgroup should be adequate.


No implants or crown failure occurred during fatigue testing in the chewing simulator. However, all crowns showed wear facets at the occlusal indenter contact point, which were more evident in the LD crowns.

The mean fracture load and standard deviations of all groups are presented in Table 1. Fracture load means of LD groups were statistically significantly lower than that of the corresponding Zr groups with P = 0.001 between Zr and LD groups supported by implant and P < 0.001 between Zr and LD groups cemented to epoxy resin dies. Comparing crowns made from the same crown material according to their supporting (implant or epoxy resin) showed no significant difference with P = 0.923 between the two Zr groups and P = 0.337 between the two LD groups. In all groups, chewing simulation caused a statistically significant reduction in the mean fracture load ranging from 7.6 to 16.3%.

Table 1.
Results of the fracture load mean and standard deviation.
Groups ( n=20) Sub group
( n=10)
Mean (St Dev) Reduction in Fracture Load after Fatigue
Implant-supported Zr Control 4054 (367)A 7.6%
Fatigued 3344 (547)a
Die-supported Zr Control 3783 (522)A 8%
Fatigued 3477 (426)a
Implant-supported LD Control 2506 (426)B 12%
Fatigued 2207 (395)b
Die-supported LD Control 2159 (231)B 16.3%
Fatigued 1806 (237)b
Different capital superscripts indicate heterogeneous subsets (P < 0.05).
Different small superscripts indicate heterogeneous subsets (P < 0.05).
Between control and fatigued subgroups: different case superscripts indicate heterogeneous subsets (P > 0.05)

Fracture test of the crowns (Zr and LD) resulted in cohesive bulk fractures involving all crown thickness, regardless of being supported by an implant or cemented to epoxy resin dies. Fractures observed can be generally categorized into three patterns; a straight fracture running mesiodistally following the central groove (2 fragments), fracture running mesiodistally, and along the lingual groove (3 fragments), or more catastrophic shuttering of the crowns into several pieces (Fig. 2). There was no specific fracture path for any of the materials; however, as clearly seen in Table 2, the distribution of different fracture patterns in the two materials indicates more catastrophic patterns in the LD crowns.

Fig. (2). Most commonly observed fractures of lithium disilicate (A) and zirconia (B) crowns.

No fracture in the epoxy resin dies was observed during fatigue. Similarly, none of the zirconia abutments neither any of the Ti-Bases or implants were fractured during fatigue or after the fracture test, and no screw loosening was observed.


Despite the 100% survival of the crowns fatigued in this study, the results showed a statistically significant reduction in mean fracture load values compared to the corresponding control groups (Table 2), which rejects the first null hypothesis. These findings are in agreement with previous studies that tested LD [43-45] and Zr restorations [43, 46]. Reduction in fracture resistance can be explained by the accumulated damage of ceramic materials occurring during fatigue testing, which ultimately weakens the restorations [47]. In addition, specifically for zirconia material, accelerated aging can significantly weaken the restorations [48, 49]. Another study [50], however, reported no significant influence of thermal cycling and mechanical loading (TCML) on the fracture resistance of zirconia crowns. Though, it should be noted that the study [50] used low loading force of 50 N.

Table 2.
Distribution of fracture patterns according to material.
Material - 2 Fragments (Percentage) 3 Fragments (Percentage) 4 or more Fragments
Zirconia crowns (implant supported and die supported) Fatigued (n=20) 16 (80%) 1 (5 %) 3 (15%)
Unfatigued control (n=20) 18 (90%) 2 (10%) 0
Lithium disilicate crowns (implant supported and die supported) Fatigued (n=20) 0 3 (15%) 17 (85%)
Unfatigued control (n=20) 6 (30%) 5 (25%) 9 (45%)

Comparing the two materials (Zr and LD) as presented in Table 1 shows that the reduction in fracture resistance was more pronounced in the LD groups. Previous studies [30, 51-54] reported a significantly higher fracture load of Zr crowns than that of LD. Additionally, reviewing the fracture patterns after single load to fracture (Table 2) shows that the majority of the zirconia crowns fractured into two pieces (buccal and lingual halves), while LD crowns, especially the fatigued ones, mostly followed more catastrophic fracture pattern into several pieces. Fractures that occurred in LD crowns may indicate the formation of internal cracks during fatigue and reflect the greater effect of chewing simulation on the material. This should be considered clinically as both materials are indicated for posterior crowns. Zirconia appears to be the reasonable choice when considerable fatigue and higher occlusal load are expected.

Nevertheless, none of the LD crowns failed during fatigue testing. The mean fracture load, although significantly lower than that of Zr was well above the fracture load required for posterior restorations [55]. This agrees with previous studies as LD posterior crowns demonstrated good clinical performance with a low prevalence of mechanical failure along different follow-up periods [56-63]. The material also showed excellent in vitro fatigue survival [64-68]. The performance of LD crowns in this study might be linked to its low modulus of elasticity (63.9 GPa) compared to that of Zr abutment. This, according to previous studies [69, 70], allows better load dissipation and enhances fracture resistance of the structure. Therefore, when the expected occlusal loads are within the normal physiologic range, the use of LD material for posterior crowns might be more satisfactory for patients because it combines strength and preferable aesthetics.

The results show that the mean fracture load value of implant-supported crowns was insignificantly higher than that of the crowns supported by epoxy resin dies, confirming the second null hypothesis. Similar results were also reported in previous studies [71, 72], as tooth or implant situations can only partially influence the fracture resistance of ceramic crowns [73]. This indicates that an implant-supported posterior crown can be just as successful as a tooth-supported crown treatment. On the contrary, a recent study [53] found significantly higher fracture load values for implant-supported LD and Zr crowns compared to tooth-supported ones. The study [53] used natural teeth, which might have influenced the results because they cannot be standardized due to inevitable individual differences in shape, quality, and geometry of the human teeth. Epoxy resin was used in this study instead of natural teeth, which might be considered a limitation. However, it was chosen to overcome the inability to standardize natural teeth specimens [74]. The elastic modulus of this material (3 GPa) is close to that of dentine (11-20 GPa) [75], and therefore, it has been previously used as a comparable alternative to simulate natural teeth and to produce standardized specimens [35, 40, 76, 77].

This study used the hybrid abutment design, which was introduced to meet the increased aesthetic demand of the patients. No failure occurred in any of the implants, Ti-Bases, or Zr abutments during fatigue. In addition, failure of the specimens after the fracture test occurred only in the crowns, which proposes a good performance of this implant abutment design. These results disagree with a recent study [25] that found that Zr and LD hybrid implant-supported crowns failed in a significant number (18.8% for Zr and 43.8% for LD) during fatigue testing despite their high fracture strength. Failures in zirconia crowns occurred in the Ti-Bases, which were short (3mm), whereas failures in LD crowns occurred in both the Ti-Bases and ceramic superstructures [25]. Thus, the authors recommended that their use as posterior restorations should be considered critically [25]. In fact, the available data on the performance of this implant design is still insufficient and more laboratory, and clinical studies are required [43, 78].

This study used a testing protocol to simulate the challenging conditions in the oral cavity, including cyclic mechanical loading, wet environment, and fluctuating temperatures [79]. Therefore, fatigue forces were applied with a simultaneous thermocycling in water between 5 °C and 55 °C all through the testing period [80] to produce the effect of these challenging conditions. In addition, a 0.3 mm lateral movement while the load is applied should mimic the lateral movement of the jaw during function and its evident destructive effect on the restorations strength [81, 82]. Nevertheless, the simulation of the periodontal ligaments in the groups cemented to epoxy resin dies was not considered in this study, which might produce some effects on the results. Further, examining the fatigued crowns under 20 × magnification is considered a limitation as Scanning Electronic Microscopy (SEM) could offer a great advantage by detecting micro-cracks and defects. It should also be noted, however, that the results of in vitro investigations have to be interpreted cautiously and cannot be transformed directly to clinical conditions; clinical studies are always crucial to judge materials and designs performance.


Within the limitations of this in vitro study, it can be concluded that both Zr and LD posterior crowns have adequate fatigue and fracture resistance required for posterior crowns. However, when heavy fatigue forces are expected, Zr material is preferable over LD. Zirconia and LD implant-supported crowns cemented to hybrid abutments should have satisfactory clinical performance under physiologic masticatory forces. The hybrid-abutment design appears as an adequate approach in implant-supported restorations.


Not applicable.


Not applicable.


Not applicable.


The data supporting the findings of the article is available from corresponding author [N. N] upon reasonable request.


This research was funded by the Deanship of Research, Jordan University of Science and Technology, Jordan and School of Medicine and Dentistry, Griffith University, AUS.


The authors declare no conflict of interest, financial or otherwise.


Declared none.


Kapos T, Evans C. CAD/CAM technology for implant abutments, crowns, and superstructures. Int J Oral Maxillofac Implants 2014; 29(Suppl.): 117-36.
Ozcan M. Fracture reasons in ceramic-fused-to-metal restorations. J Oral Rehabil 2003; 30(3): 265-9.
Adell R, Lekholm U, Rockler B, Brånemark P-I. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981; 10(6): 387-416.
Aldegheishem A, Ioannidis G, Att W, Petridis H. Success and survival of various types of all-ceramic single crowns: A critical review and analysis of studies with a mean follow-up of 5 years or longer. Int J Prosthodont 2017; 30(2): 168-81.
Ho GW, Matinlinna JP. Insights on ceramics as dental materials. Part I: Ceramic material types in dentistry. Silicon 2011; 3(3): 109-15.
Scherrer SS, De Rijk WG, Wiskott HW, Belser UC. Incidence of fractures and lifetime predictions of all-ceramic crown systems using censored data. Am J Dent 2001; 14(2): 72-80.
Sulaiman F, Chai J, Jameson LM, Wozniak WT. A comparison of the marginal fit of In-Ceram, IPS Empress, and Procera crowns. Int J Prosthodont 1997; 10(5): 478-84.
Larsson C, Vult von Steyern P. Five-year follow-up of implant-supported Y-TZP and ZTA fixed dental prostheses. A randomized, prospective clinical trial comparing two different material systems. Int J Prosthodont 2010; 23(6): 555-61.
Larsson C, Vult von Steyern P. Ten-year follow-up of implant-supported all-ceramic fixed dental prostheses: A randomized, prospective clinical trial. Int J Prosthodont 2016; 29(1): 31-4.
Larsson C, Wennerberg A. The clinical success of zirconia-based crowns: A systematic review. Int J Prosthodont 2014; 27(1): 33-43.
Fasbinder DJ, Dennison JB, Heys D, Neiva G. A clinical evaluation of chairside lithium disilicate CAD/CAM crowns: A two-year report. J Am Dent Assoc 2010; 141(S2)(Suppl. 2): 10S-4S.
Etman MK, Woolford MJ. Three-year clinical evaluation of two ceramic crown systems: A preliminary study. J Prosthet Dent 2010; 103(2): 80-90.
Makhija SK, Lawson NC, Gilbert GH, et al. Dentist material selection for single-unit crowns: Findings from the National Dental Practice-Based Research Network. J Dent 2016; 55: 40-7.
Alcaraz MGR, Veitz-Keenan A, Sahrmann P, et al. Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth. Cochrane Database Sys Rev 2014; 3.
Edelhoff D, Sorensen JA. Tooth structure removal associated with various preparation designs for anterior teeth. J Prosthet Dent 2002; 87(5): 503-9.
Edelhoff D, Sorensen JA. Tooth structure removal associated with various preparation designs for posterior teeth. Int J Periodontics Restorative Dent 2002; 22(3): 241-9.
Adell R, Eriksson B, Lekholm U, Brånemark PI, Jemt T. Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac Implants 1990; 5(4): 347-59.
Buser D, Janner SF, Wittneben JG, Brägger U, Ramseier CA, Salvi GE. 10-year survival and success rates of 511 titanium implants with a sandblasted and acid-etched surface: a retrospective study in 303 partially edentulous patients. Clin Implant Dent Relat Res 2012; 14(6): 839-51.
Jung RE, Zembic A, Pjetursson BE, Zwahlen M, Thoma DS. Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years. Clin Oral Implants Res 2012; 23(Suppl. 6): 2-21.
Rabel K, Spies BC, Pieralli S, Vach K, Kohal RJ. The clinical performance of all-ceramic implant-supported single crowns: A systematic review and meta-analysis. Clin Oral Implants Res 2018; 29(Suppl. 18): 196-223.
Pjetursson BE, Sailer I, Makarov NA, Zwahlen M, Thoma DS. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part II: Multiple-unit FDPs. Dent Mater 2015; 31(6): 624-39.
Al-Quran FA, Al-Ghalayini RF, Al-Zu’bi BN. Single-tooth replacement: Factors affecting different prosthetic treatment modalities. BMC Oral Health 2011; 11(1): 34.
Honda J, Komine F, Kamio S, et al. Fracture resistance of implant-supported screw-retained zirconia-based molar restorations. Clin Oral Implants Res 2016.
Elshiyab SH, Nawafleh N, Walsh L, George R. Fracture resistance and survival of implant-supported, zirconia-based hybrid-abutment crowns: Influence of aging and crown structure. J Investig Clin Dent 2018; 9(4)e12355
Nouh I, Kern M, Sabet AE, Aboelfadl AK, Hamdy AM, Chaar MS. Mechanical behavior of posterior all-ceramic hybrid-abutment-crowns versus hybrid-abutments with separate crowns-A laboratory study. Clin Oral Implants Res 2019; 30(1): 90-8.
Al-Zordk W, Elmisery A, Ghazy M. Hybrid-abutment-restoration: effect of material type on torque maintenance and fracture resistance after thermal aging. Int J Implant Dent 2020; 6(1): 24.
Nawafleh N, Bibars AR, Al Twal E, Öchsner A. Influence of antagonist material on fatigue and fracture resistance of zirconia crowns. Eur J Dent 2020; 14(2): 200-5.
Elshiyab SH, Nawafleh N, Khan U, Öchsner A, George R. Impact of coping veneering techniques on the survival of implant-supported zirconia-based-crowns cemented to hybrid-abutments: An in-vitro study. Bioengineering (Basel) 2020; 7(4): 117-30.
Mitsias M, Koutayas SO, Wolfart S, Kern M. Influence of zirconia abutment preparation on the fracture strength of single implant lithium disilicate crowns after chewing simulation. Clin Oral Implants Res 2014; 25(6): 675-82.
Baladhandayutham B, Lawson NC, Burgess JO. Fracture load of ceramic restorations after fatigue loading. J Prosthet Dent 2015; 114(2): 266-71.
Liu Y, Gao S, Han Y, Yang Q, Arola D, Zhang D. Bearing capacity of ceramic crowns before and after cyclic loading: An in vitro study. J Mech Behav Biomed Mater 2018; 87: 197-204.
Hosseini M, Kleven E, Gotfredsen K. Fracture mode during cyclic loading of implant-supported single-tooth restorations. J Prosthet Dent 2012; 108(2): 74-83.
Bankoğlu Güngör M, Karakoca Nemli S. Fracture resistance of CAD-CAM monolithic ceramic and veneered zirconia molar crowns after aging in a mastication simulator. J Prosthet Dent 2018; 119(3): 473-80.
Johansson C, Kmet G, Rivera J, Larsson C, Vult Von Steyern P. Fracture strength of monolithic all-ceramic crowns made of high translucent yttrium oxide-stabilized zirconium dioxide compared to porcelain-veneered crowns and lithium disilicate crowns. Acta Odontol Scand 2014; 72(2): 145-53.
Nawafleh N, Hatamleh MM, Öchsner A, Mack F. The impact of core/veneer thickness ratio and cyclic loading on fracture resistance of lithium disilicate crown. J Prosthodont 2018; 27(1): 75-82.
Homaei E, Farhangdoost K, Pow EHN, et al. Fatigue resistance of monolithic CAD/CAM ceramic crowns on human premolars. Ceram Int 2016; 42(14): 15709-17.
Obermeier M, Ristow O, Erdelt K, Beuer F. Mechanical performance of cement- and screw-retained all-ceramic single crowns on dental implants. Clin Oral Investig 2018; 22(2): 981-91.
Garoushi S, Säilynoja E, Vallittu PK, Lassila L. Fracture-behavior of CAD/CAM ceramic crowns before and after cyclic fatigue aging. Int J Prosthodont in press
Wang R-R, Lu C-L, Wang G, Zhang D-S. Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns. Int J Oral Sci 2014; 6(2): 99-104.
Nawafleh NA, Hatamleh MM, Öchsner A, Mack F. Fracture load and survival of anatomically representative monolithic lithium disilicate crowns with reduced tooth preparation and ceramic thickness. J Adv Prosthodont 2017; 9(6): 416-22.
Faul F, Erdfelder E, Buchner A, Lang A-G. Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behav Res Methods 2009; 41(4): 1149-60.
Cohen J. Statistical power analysis. Curr Dir Psychol Sci 1992; 1(3): 98-101.
Elshiyab SH, Nawafleh N, Öchsner A, George R. Fracture resistance of implant- supported monolithic crowns cemented to zirconia hybrid-abutments: Zirconia-based crowns vs. lithium disilicate crowns. J Adv Prosthodont 2018; 10(1): 65-72.
Zhao K, Wei YR, Pan Y, Zhang XP, Swain MV, Guess PC. Influence of veneer and cyclic loading on failure behavior of lithium disilicate glass-ceramic molar crowns. Dent Mater 2014; 30(2): 164-71.
Seydler B, Rues S, Müller D, Schmitter M. In vitro fracture load of monolithic lithium disilicate ceramic molar crowns with different wall thicknesses. Clin Oral Investig 2014; 18(4): 1165-71.
Aboushelib MN, Wang H, Kleverlaan CJ, Feilzer AJ. Fatigue behavior of zirconia under different loading conditions. Dent Mater 2016; 32(7): 915-20.
Kelly JR. Clinically relevant approach to failure testing of all-ceramic restorations. J Prosthet Dent 1999; 81(6): 652-61.
Sato T, Shimada M. Control of the tetragonal-to-monoclinic phase transformation of yttria partially stabilized zirconia in hot water. J Mater Sci 1985; 20(11): 3988-92.
Sato T, Shimada M. Transformation of yttria-doped tetragonal ZrO2 polycrystals by annealing in water. J Am Ceram Soc 1985; 68(6): 356-56.
Mitov G, Anastassova-Yoshida Y, Nothdurft FP, von See C, Pospiech P. Influence of the preparation design and artificial aging on the fracture resistance of monolithic zirconia crowns. J Adv Prosthodont 2016; 8(1): 30-6.
Choi JW, Kim SY, Bae JH, Bae EB, Huh JB. In vitro study of the fracture resistance of monolithic lithium disilicate, monolithic zirconia, and lithium disilicate pressed on zirconia for three-unit fixed dental prostheses. J Adv Prosthodont 2017; 9(4): 244-51.
Zhang Y, Mai Z, Barani A, Bush M, Lawn B. Fracture-resistant monolithic dental crowns. Dent Mater 2016; 32(3): 442-9.
Preis V, Behr M, Rosentritt M. In vitro fatigue and fracture testing of implant-supported anterior ceramic crowns. Int J Prosthodont 2018; 31(3): 264-6.
Pereira GKR, Graunke P, Maroli A, et al. Lithium disilicate glass-ceramic vs translucent zirconia polycrystals bonded to distinct substrates: Fatigue failure load, number of cycles for failure, survival rates, and stress distribution. J Mech Behav Biomed Mater 2019; 91: 122-30.
Chitmongkolsuk S, Heydecke G, Stappert C, Strub JR. Fracture strength of all-ceramic lithium disilicate and porcelain-fused-to-metal bridges for molar replacement after dynamic loading. Eur J Prosthodont Restor Dent 2002; 10(1): 15-22.
Kern M, Sasse M, Wolfart S. Ten-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic. J Am Dent Assoc 2012; 143(3): 234-40.
Pieger S, Salman A, Bidra AS. Clinical outcomes of lithium disilicate single crowns and partial fixed dental prostheses: A systematic review. J Prosthet Dent 2014; 112(1): 22-30.
Reich S, Schierz O. Chair-side generated posterior lithium disilicate crowns after 4 years. Clin Oral Investig 2013; 17(7): 1765-72.
Malament KA, Natto ZS, Thompson V, Rekow D, Eckert S, Weber HP. Ten-year survival of pressed, acid-etched e.max lithium disilicate monolithic and bilayered complete-coverage restorations: Performance and outcomes as a function of tooth position and age. J Prosthet Dent 2019; 121(5): 782-90.
Rauch A, Reich S, Dalchau L, Schierz O. Clinical survival of chair-side generated monolithic lithium disilicate crowns:10-year results. Clin Oral Investig 2018; 22(4): 1763-9.
Mobilio N, Fasiol A, Catapano S. Survival rates of lithium disilicate single restorations: A retrospective study. Int J Prosthodont 2018; 31(3): 283-6.
Aziz A, El-Mowafy O, Tenenbaum HC, Lawrence HP, Shokati B. Clinical performance of chairside monolithic lithium disilicate glass-ceramic CAD-CAM crowns. J Esthet Restor Dent 2019; 31(6): 613-9.
Malament KA, Margvelashvili-Malament M, Natto ZS, Thompson V, Rekow D, Att W. Comparison of 16.9-year survival of pressed acid etched e.max lithium disilicate glass-ceramic complete and partial coverage restorations in posterior teeth: Performance and outcomes as a function of tooth position, age, sex, and thickness of ceramic material. J Prosthet Dent 2021; 126(4): 533-45.
Altamimi AM, Tripodakis AP, Eliades G, Hirayama H. Comparison of fracture resistance and fracture characterization of bilayered zirconia/fluorapatite and monolithic lithium disilicate all ceramic crowns. Int J Esthet Dent 2014; 9(1): 98-110.
Carvalho AO, Bruzi G, Giannini M, Magne P. Fatigue resistance of CAD/CAM complete crowns with a simplified cementation process. J Prosthet Dent 2014; 111(4): 310-7.
Nawafleh N, Hatamleh M, Elshiyab S, Mack F. Lithium disilicate restorations fatigue testing parameters: A systematic review. J Prosthodont 2016; 25(2): 116-26.
Ferruzzi F, Ferrairo BM, Piras FF, Borges AFS, Rubo JH. Fatigue survival and damage modes of lithium disilicate and resin nanoceramic crowns 2019; 27.
Camatta HP, Ferreira RM, Ferrairo BM, et al. Mechanical behavior and fracture loads of screw retained and cement-retained lithium disilicate implant supported crowns. J Prosthodont 2021; 30(8): 690-7.
Datte CE, Tribst JP, Dal Piva AO, et al. Influence of different restorative materials on the stress distribution in dental implants. J Clin Exp Dent 2018; 10(5): e439-44.
Tribst JPM, Dal Piva AMO, Borges ALS, Bottino MA. Different combinations of CAD/CAM materials on the biomechanical behavior of a two-piece prosthetic solution. Int J Comput Dent 2019; 22(2): 171-6.
Preis V, Hahnel S, Behr M, Bein L, Rosentritt M. In-vitro fatigue and fracture testing of CAD/CAM-materials in implant-supported molar crowns. Dent Mater 2017; 33(4): 427-33.
Rosentritt M, Hahnel S, Engelhardt F, Behr M, Preis V. In vitro performance and fracture resistance of CAD/CAM-fabricated implant supported molar crowns. Clin Oral Investig 2017; 21(4): 1213-9.
Preis V, Hahnel S, Behr M, Rosentritt M. In vitro performance and fracture resistance of novel CAD/CAM ceramic molar crowns loaded on implants and human teeth. J Adv Prosthodont 2018; 10(4): 300-7.
Cho L, Song H, Koak J, Heo S. Marginal accuracy and fracture strength of ceromer/fiber-reinforced composite crowns: Effect of variations in preparation design. J Prosthet Dent 2002; 88(4): 388-95.
Kinney JH, Marshall SJ, Marshall GW. The mechanical properties of human dentin: A critical review and re-evaluation of the dental literature. Crit Rev Oral Biol Med 2003; 14(1): 13-29.
Nakamura K, Ankyu S, Nilsson F, et al. Critical considerations on load-to-failure test for monolithic zirconia molar crowns. J Mech Behav Biomed Mater 2018; 87: 180-9.
Badran N, Abdel Kader S, Alabbassy F. Effect of Incisal Porcelain Veneering Thickness on the Fracture Resistance of CAD/CAM Zirconia All-Ceramic Anterior Crowns. Int J Dent 2019; 20196548519
Honda J, Komine F, Kamio S, Taguchi K, Blatz MB, Matsumura H. Fracture resistance of implant-supported screw-retained zirconia-based molar restorations. Clin Oral Implants Res 2017; 28(9): 1119-26.
Alessandretti R, Borba M, Della Bona A. Cyclic contact fatigue resistance of ceramics for monolithic and multilayer dental restorations. Dent Mater 2020; 36(4): 535-41.
Gale MS, Darvell BW. Thermal cycling procedures for laboratory testing of dental restorations. J Dent 1999; 27(2): 89-99.
Kim B, Zhang Y, Pines M, Thompson VP. Fracture of porcelain-veneered structures in fatigue. J Dent Res 2007; 86(2): 142-6.
Kim J-W, Kim J-H, Thompson VP, Zhang Y. Sliding contact fatigue damage in layered ceramic structures. J Dent Res 2007; 86(11): 1046-50.