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Review

Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance

by
Sohaib Fadhil Mohammed
1,*,
Mohd Firdaus Yhaya
2,
Matheel Al-Rawas
3 and
Tahir Yusuf Noorani
4,*
1
Department of Operative Dentistry, College of Dentistry, University of Anbar, Baghdad 55431, Iraq
2
Biomaterials Synthesis Laboratory, School of Dental Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu 16150, Kelantan, Malaysia
3
Prosthodontic Unit, School of Dental Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu 16150, Kelantan, Malaysia
4
Conservative Dentistry Unit, School of Dental Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu 16150, Kelantan, Malaysia
*
Authors to whom correspondence should be addressed.
Ceramics 2026, 9(5), 50; https://doi.org/10.3390/ceramics9050050
Submission received: 8 April 2026 / Revised: 29 April 2026 / Accepted: 8 May 2026 / Published: 13 May 2026
Browse Figures
Versions Notes

Abstract

The use of zirconia as a material in the base of modern restorative dentistry is due to its high strength, biocompatibility, and improved aesthetic performance. The aim of this review is to provide an integrated and coherent overview of the recent developments in zirconia crowns by focusing on the development of materials, microstructure, digital fabrication processes, optical capabilities, and clinical performance. A survey of literature in the form of a narrative literature review was conducted in the most significant databases, such as PubMed, Scopus, Web of Science, and Google Scholar, including publications published since 2000, with a focus on systematic reviews, meta-analyses, clinical studies, and materials science studies. The results show that zirconia materials have developed beyond traditional 3Y-TZP systems, characterized by high strength and fracture toughness to high-translucency and multilayer zirconia (4Y 6Y-PSZ) systems, which provide better aesthetics at the cost of lower mechanical reliability. The implementation of CAD/CAM technologies has enhanced the accuracy of fabrication, marginal fit and reproducibility and the development of sintering, surface modification and bonding protocols has enhanced clinical performance. Recent clinical results have shown high survival rates (around 85–95 percent over 5–10 years), and the results depend on the design of the restoration, the zirconia generation, and the functional loading circumstances. Despite these developments, there are still concerns about the durability of bonding, trade-offs between translucency and strength, and long-term performance of high-translucency zirconia. The development of new technologies, such as additive manufacturing, design-aided artificial intelligence, and bioactive surface modification, is a promising avenue toward improving clinical reliability and performance.

1. Introduction

The innovations in the field of dental restorative materials are preconditioned by the fact that researchers continue to seek a good balance between mechanical strength, biocompatibility, and aesthetic performance. Traditionally, the application of metal–ceramic restorations has prevailed in the use of fixed dental restorations, especially in posterior teeth, because of the high mechanical strength and long-term clinical stability of this type of restoration. However, fully ceramic systems with zirconia-based restorations are gaining popularity in the anterior dental region because of their better esthetics and increased optical characteristics [1,2,3]. The possibility of making premier dental products appeared with the appearance of zirconium dioxide (zirconia) in the dental market, which offers better mechanical properties along with better aesthetics due to its monolithic structure [4].
Mechanical properties of zirconia differ significantly because of the concentration of yttria and microstructure [5]. Traditional 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystal) has a flexural strength of 800–1200 MPa and a fracture toughness of approximately 5–10 MPa·m1/2, which is due to its transformation toughening mechanism [4,6]. On the other hand, newer generations of zirconia, such as 4Y-PSZ, 5Y-PSZ, and 6Y-PSZ, have a higher ratio of cubic phase that increases translucency but reduces mechanical strength and fracture toughness [2,7]. The good strength of zirconia can be attributed to its transformation toughening, which involves the conversion of tetragonal crystals into monoclinic crystals by tensile stress and the resultant compressive forces preventing the propagation of cracks [8].
The zirconia has also seen significant improvements in optical properties due to composition, grain size, and sintering improvements. These innovations have enabled the creation of highly translucent zirconia, allowing it to mimic natural teeth and remove the need for ceramic veneers [9,10]. At the same time, the introduction of computer-aided design and computer-aided manufacturing (CAD/CAM) has revolutionized the manufacturing of zirconia crowns in terms of precision, marginal fit, and production efficiency [11]. Additional improvements in sintering processing, surface finishing, and bonding procedures have increased the stability and durability of clinical outcomes with zirconia restorations.
Clinical and laboratory research has shown that zirconia restorations have high mechanical reliability, superior biocompatibility, and positive patient outcomes and have been widely used in modern restorative dentistry [1,5,12,13]. Observational evidence has also recently highlighted the increased importance of zirconia as a biomaterial, incorporated into biomechanical and aesthetic performance in modern prosthodontics. Moreover, zirconia is particularly advantageous to patients with metal sensitivities due to its high biocompatibility and lack of tendency to accumulate plaque [14]. Nevertheless, bonding reliability, translucency optimization, and long-term aging behavior should be further investigated.
Despite many studies carried out on zirconia, several systematic and narrative reviews have overwhelmingly focused on the individual properties of zirconia crowns, including mechanical properties, clinical survival, optical performance, or CAD/CAM fabrication technologies. To be specific, previous reviews emphasized transformation toughening mechanisms and structural reliability, but more recent studies have focused on clinical outcomes and innovations in digital dentistry [7,15]. However, such reviews often evaluate the domains separately, which provides a disconnected picture of zirconia materials and their overall use in clinical practice. This also highlights the importance of clinically oriented models that can interconnect the choice of zirconia material and the indication-specific restorative planning [16]. Moreover, the new innovations, such as high-translucency zirconia, multilayer and hybrid, artificial intelligence-driven digital workflows, and bioactive surface modifications, have not been integrated into a single analytical model. As a result, there is an apparent literature gap with regard to combining material science, manufacturing technologies, aesthetic optimization, and long-term clinical performance. In this regard, this review aims to provide a comprehensive, up-to-date review of zirconia crowns, focusing on their material development, microstructure, fabrication techniques, aesthetics, and clinical results. Also, this review outlines current limitations, compares zirconia with other indirect restorative materials, and outlines future research directions to maximize its use in modern prosthodontics. Figure 1 presents the key factors that catalyzed the development of zirconia, such as material composition, digital workflows, and clinical requirements.

2. Materials and Methods (Literature Search Strategy)

A narrative literature review was performed to synthesize recent developments in zirconia crowns with a focus on mechanical strength, aesthetic properties, manufacturing technologies, and clinical performance. The literature search was conducted using the main electronic scientific databases (PubMed, Scopus, Web of Science and Google Scholar) to retrieve sources on dental restorations using zirconia. The main terms used in the search were zirconia crowns; CAD/CAM dentistry; yttria-stabilized zirconia; translucency; mechanical properties; clinical performance. The words were searched alone and in combination with the Boolean operators (AND, OR) to obtain a list of relevant publications. Articles published from 2000 to 2025 were selected as this spans the timeframe of zirconia materials and digital technologies development. The articles were selected from peer-reviewed journals, such as systematic reviews, meta-analyses, case reports, clinical trials and material science studies, that covered composition, microstructure, optical properties, processing and clinical performance of zirconia. Other articles were also filtered to cover the topic as fully as possible, as they are also cited in other relevant articles. Research articles were chosen on the basis of scientific relevance to zirconia crowns, such as mechanical and aesthetic characteristics, computer-aided design (CAD) and computer-aided manufacturing (CAM) for zirconia crowns, and clinical outcomes of zirconia crowns. Irrelevant papers were removed and those without sufficient scientific merit were disregarded. The selected papers were then critically analysed and grouped into several key areas that cover the evolution of zirconia materials, the fabrication process, aesthetics, clinical outcomes, challenges and questions for further research. This review process enabled a thorough compilation of the existing scientific information on zirconia crowns and their use in modern prosthodontic care.

3. Evolution of Zirconia Materials in Dentistry

Dental zirconia materials have evolved in response to recent developments in material and manufacturing technologies, as well as clinical needs. Zirconia has evolved from being a high-strength material used in frameworks to a range of restorations, with different compositions and microstructures designed for specific clinical indications. This evolution is also described in recent reviews as a continuous quest for improved structural and clinical performance among the generations of zirconia materials [17]. This improvement has resulted in a range of zirconia generations, each with a particular content of yttria, phase transformation and optical characteristics. Understanding this evolution is crucial to understanding the link between material design, physical properties, aesthetic results and clinical data. As such, this section presents the evolution of zirconia and then offers a general description of its current structures, used in prosthodontic formulations [7].
The mechanical properties, biocompatibility and esthetic properties of zirconia have seen it widely applied in dental and orthopedic devices [2,4]. Recent advances in its formulation, manufacturing and digital technologies have significantly enhanced its performance. The introduction of material science technologies combined with digital manufacturing has promoted zirconia to a strategic restorative element in modern dentistry [11].

3.1. Historical Development

Dental applications of zirconia have developed over several decades, starting as an industrial material and up to the present as a leading biomaterial in restorative dentistry, as shown in Figure 2, which represents the chronological shift of zirconia uses in industry to the contemporary digital prosthodontic systems. In 1789, Martin Heinrich Klaproth identified the element zirconium in the mineral zircon; however, the pure zirconium and its oxide compounds were defined and elaborated later [4].
Zirconia was first industrially used in the nineteenth and early twentieth centuries, due to its high thermal stability as well as chemical resistance. The biological potential of zirconia was recognized in the middle of the twentieth century, and in 1969, Helmer and Driskell suggested zirconia as a potential biomaterial. A breakthrough came in 1975, when Garvie, Hannink, and Pascoe described zirconia as a ceramic steel, highlighting its transformation toughening mechanism and increased resistance to fracture [8]. This innovativeness was a foundation for using zirconia in load-bearing situations.
Zirconia attracted increased attention in the field of dentistry in the late 1980s and 1990s because of its higher biocompatibility and mechanical properties. The first applications in dentistry primarily involved implant components and substructures of fixed prostheses. However, due to the inherent opaqueness, zirconia structures were generally overlaid with porcelain to achieve decent aesthetic outcomes [4].
The beginning of the 2000s was a time of clinical integration of zirconia due to the introduction of CAD/CAM systems in fixed dental prostheses. Procera, Lava, and Cercon (commercial) supported the creation of zirconia frameworks with more accuracy and mechanical stability, leading to the popularity of zirconia-based restorations. The development of digital manufacturing and material processing supported these improvements and enhanced marginal adaptation, structural integrity, and long-term performance of zirconia prostheses [2,11,18].
The application of zirconia in fixed dental prostheses increased significantly between 2005 and 2010, which is in line with the fast development in digital dentistry. Recently, material engineering has led to high-translucency zirconia and multilayer systems, allowing monolithic restorations to be fabricated with improved esthetics and mechanical characteristics. These inventions form the latest stage of the development of zirconia materials in modern prosthodontics [7,19].

3.2. Classification of Zirconia

The aesthetic performance of zirconia restorations has significantly improved with the development of zirconia materials classified according to yttria content and structural configuration (3Y-TZP, 4Y-PSZ, 5Y-PSZ, and 6Y-PSZ) which determine their mechanical strength, phase composition, and optical properties [5]. Such compositional and phase-specific differences are essential to the explanation of the current opportunities and limitations of the zirconia-based dental materials [20]. Figure 3 is a schematic illustration of how zirconia is classified by yttria content and phase structure, in which the higher the translucency, the more the systems are dominated by cubic phase rather than tetragonal structures. The introduction of CAD/CAM technology has expanded the range of zirconia materials available for dental restorations, enabling improved precision, mechanical performance, and esthetic outcomes [21,22]. The first and most used zirconia material in dentistry is the conventional 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystal). It is distinguished by a major crystal structure presented as tetragonal, which gives it a high level of flexural strength of above 1 GPa and great fracture toughness due to transformation toughening processes, as summarized in Table 1 [23,24]. Nevertheless, standard 3Y-TZP is rather opaque due to the light scattering at the grain boundaries and the presence of the alumina additives in the microstructure [25].
The creation of zirconia materials has been gradually developed, as shown in Table 1, and has shown a distinct negative relationship between translucency and mechanical properties. With increasing yttria content from 3Y-TZP to 6Y-PSZ, the cubic phase of yttria-stabilized zirconia increases, resulting in greater translucency but reduced fracture toughness and flexural strength. As such, lower yttria-containing zirconia (3Y-TZP) is preferred for high-stress posterior regions, whereas higher-yttria-containing zirconia (5Y-PSZ and 6Y-PSZ) is mostly used in anterior regions where translucency is critical for esthetics. Multilayer zirconia systems aim to overcome this constraint by combining translucency and strength, thus increasing their flexibility for clinical use.
Subsequent generations of zirconia were created to enhance esthetic qualities by adding more yttria that stabilizes a larger percentage of the cubic phase. They are usually known as partially stabilized zirconia (PSZ). 4Y-PSZ zirconia offers a middle ground of mechanical strength and optical transparency, but 5Y-PSZ and 6Y-PSZ have more cubic phase, which makes them much more optically translucent but results in less transformation toughening and mechanical strength than 3Y-TZP [9,26]. CAD/CAM zirconia blocks can also be categorized structurally and optically, i.e., monochromatic zirconia with uniform composition, polychromatic multilayer zirconia with uniform composition, and polychromatic multilayer zirconia with hybrid composition [18]. Monochromatic zirconia blocks come with the same composition and shade through the material and also have the 3Y-TZP and more translucent types of zirconia, e.g., 4Y-PSZ, 5Y-PSZ. Conversely, hue-graded polychromatic multilayer zirconia involves the use of color grading between several layers but keeps the same yttria level in all the blocks and is usually referred to as M3Y, M4Y, and M5Y materials. Such multilayer systems enable a better replication of the color of natural teeth without changes in the inherent composition of zirconia [27]. A more modern evolution is the polychromatic multilayer zirconia, having a hybrid composition, where the color as well as the composition of the layer changes. In such materials, varying zirconia compositions (3Y-TZP mixed with 4Y- or 5Y-PSZ) are placed in the same block to generate gradients both on mechanical and optical properties [28]. The layers that are heavier, 3Y-rich, are usually in the cervical part, so that the fracture resistance is high, whereas the layers, which are more translucent, are in the incisal part to enhance esthetics. These multilayer hybrid zirconia systems are considered to be one of the significant developments in zirconia technology, as they could provide clinicians with a better balance between strength, translucency, and natural tooth-like appearance of monolithic restorations modeled with the help of digital CAD/CAM systems [2]. In general, the zirconia classification based on the yttria levels and the structure design indicates the ongoing evolution of zirconia ceramics with the goal of maximizing both mechanical stability and aesthetic performance in the current dental restorations.

4. Manufacturing Processes and Digital Workflow

The modern manufacturing processes with the application of CAD/CAM systems and processing technologies have significantly influenced the development of zirconia-based restoration technology. The high level of technological integration resulted in three major improvements: improved performance, increased precision, and material production, which combined to reduce the errors during the process and lead to improved clinical outcomes. The use of digital advances has made Zirconia an essential prosthodontic component with superior milling and sintering in the development of dental technology [29].

4.1. CAD/CAM Technology in Zirconia Crown Fabrication

The advent of CAD/CAM technologies has significantly revolutionized the production of zirconia crowns via standardized, reproducible, and highly precise manufacturing [11]. These digital workflows include three main steps, namely data acquisition, computer-aided design, and computer-aided manufacturing, as shown in Figure 4.
The scans are taken using intraoral or laboratory scanners, which are capable of taking high-resolution 3D data of the prepared tooth and surrounding structures. Compared to traditional impression methods, digital impressions have been shown to be less distorted and more accurate and, hence, increase the marginal adaptation of restorations [30]. The data obtained is then loaded into CAD by using DentalCAD 3.3 Chemnitz software (exocad GmbH, Darmstadt, Germany), where the restoration is planned digitally. The stage offers precise control of the occlusal morphology, proximal contacts, and the thickness of the restoration, which allows standardized design parameters and reduces variation based on the operator. The CAM step involves machining zirconia restorations out of pre-sintered zirconia blocks using multi-axis milling machines with high precision. The pre-sintered zirconia can be machined more easily and then is subjected to a final sintering step at about 1400–1500 °C to give full densification and the best mechanical characteristics [2]. The effects of sintering parameters on the long-term stability of materials are complex. Despite the strength increase with adequate densification, overly high sintering temperatures or prolonged holding times may promote abnormal grain growth, which is associated with reduced resistance to low-temperature degradation (LTD) due to a lower stability of the tetragonal phase. This means that careful optimization of sintering conditions must be conducted to balance densification, control of grain sizes, and hydrothermal aging resistance [2,6,24].
Several investigations have revealed that CAD/CAM-produced zirconia restorations exhibit clinically acceptable marginal gaps, usually less than 50–100 μm, which is associated with a reduced probability of microleakage and secondary caries [11]. In addition, digital fabrication also minimizes manual error and enhances reproducibility compared to traditional laboratory techniques.
The post-processing procedures, including polishing and glazing, play an essential role in enhancing the smoothness of surfaces and their wear characteristics. The importance of appropriate finishing guidelines has been highlighted by highly polished zirconia surfaces being shown to reduce the antagonist enamel wear in comparison with rough or glazed surfaces [31].
Recent advances in CAD/CAM systems include the use of artificial intelligence (AI) and automatic design algorithms that help optimize restoration morphology and the allocation of occlusal loads. These technologies have the potential to improve the predictability and consistency of zirconia restorations, but long-term clinical outcomes of these technologies require further research [32].

4.2. Innovations in Manufacturing Techniques

Recent advances in the zirconia fabrication techniques focus on the control of microstructure, mechanical properties, and aesthetic features with improved processing techniques. Modern zirconia processing includes the fabrication of structured zirconia discs through different methods of material arrangement. Several layers of yttria-stabilized layering in a single block produce better mechanical strength and maintain optical clarity. Multilayer zirconia systems have much better stress distribution than single-layer systems, hence, improving fracture resistance and long-term performance [2,7].
Cold isostatic pressing (CIP) and hot isostatic pressing (HIP) are processing technologies that have significantly enhanced zirconia density and reduced internal defects. CIP helps in compacting powder and reducing porosity, and HIP eliminates remaining pores and improves the structural integrity, thus raising the mechanical strength and reliability [6,18].
Sintering in Zirconia plays a vital role in the manufacturing process. Well-designed sintering profiles are needed to achieve full densification and avoid excessive grain growth. To maintain phase stability, strength and low-temperature degradation, it is crucial to control the sintering process [6,24].
In addition to traditional processing technologies, the advent of additive manufacturing has revolutionized zirconia processing. Methods like stereolithography (SLA), digital light processing (DLP), and direct inkjet printing allow for the fabrication of complex shapes with high resolution and low material waste. These technologies enable the fabrication of personalized restorations and implant-supported frameworks with tailored macro- and microstructures, which may improve integration and function [33].
Moreover, surface treatments have become important strategies to improve zirconia bonding and clinical success. Techniques like air-abrasion, plasma activation, laser microgrooving, and selective infiltration etching (SIE) have been shown to enhance the bonding of zirconia to resin cements. These techniques enhance surface energy and provide mechanical retention, and thus, prevent debonding and failure of the restoration [34,35].
Additionally, recent digital technologies such as artificial intelligence (AI)-supported design and digital twins are being explored to enhance the manufacturing of zirconia restorations. These systems allow for stress and prosthesis performance prediction, facilitating a more tailored approach to prosthesis fabrication. However, further studies are needed to verify their long-term clinical feasibility [32]. Figure 5 shows the shift between pre-sintered milled zirconia to fully sintered restorations with a focus on the effects of sintering on mechanical strength and translucency.

5. Enhancements in Aesthetic Properties of Zirconia

Aesthetic performance of zirconia restorations has significantly increased due to the development of material processing, microstructural control, and surface finishing processes. Unlike the classification of zirconia material, which is according to yttria content and phase composition as discussed in Section 3.2, this section highlights clinically important optical performance, including translucency, light interaction, and surface-related aesthetic performance that directly influence the esthetics of the restorations. First-generation zirconia restorations showed poor translucency because of heavy scattering of light in the material, mostly at grains, alumina, and heterogeneity of the phases. As a result, zirconia was first utilized as a framework material, and veneering ceramics are required to attain appropriate esthetics. However, light transmission has improved significantly in recent years with advances in processing techniques, such as alumina content and grain size optimization during sintering to enable more aesthetically pleasing monolithic zirconia restorations [10,36].
Along with translucency, the optical performance of zirconia is determined by other effects, such as opalescence, fluorescence, and contrast ratio. The opalescence refers to the scattering effect of shorter wavelengths of light by a material to produce a bluish appearance in reflected light and a warmer appearance in transmitted light, like natural enamel. Fluorescence is the emission of visible light under ultraviolet light stimulation, imparting restorations with a vibrant appearance and a natural look under different light sources. The contrast ratio measures the masking ability of zirconia on substrates and is essential for masking discolored or metal posts. The grain size, phase distribution, and additive content play significant roles in determining these optical properties, which in turn affect the light-scattering behavior of zirconia ceramics [10,36].
Further improvements in the visual quality of zirconia restorations have been made by developing surface treatment and polishing technologies. High-gloss polishing reduces the roughness of the surface, enhances light reflection and translucency, decreases plaque accumulation, and helps in maintaining the long-term color stability. Compared to glazed surfaces, polished zirconia has a more stable optical performance and wear properties in many cases, which makes it clinically more favorable [31].
In addition, the sintering parameters play a key role in influencing the final optical properties of zirconia. Light transmission and translucency are influenced by regulated grain growth and the stability of phases during sintering. Overgrown grain development may impair mechanical stability and enhance translucency, and thus it is important to optimize processing conditions to obtain a balance between aesthetics and strength [2,37].
A combination of zirconia and digital dentistry technologies has also increased aesthetic outcomes. The CAD/CAM systems, digital smile design, and AI-assisted shade matching allow the accurate control of the restoration morphology, shade gradients, and anatomy. These technologies allow clinicians and dental technicians to produce restorations that are very similar to natural dentition and therefore enhance the overall aesthetic integration [32]. This claim is also supported by clinical case reports, which report successful aesthetic rehabilitation using layered zirconia veneers and crowns in complex cases such as spaced dentition and defective restorations, where both optical integration and functional correction are achieved [38]. Figure 6 shows the stages of a digital workflow, starting with the design and progressing to the final restoration, which are gradually advancing in morphology, surface quality, and translucency.

6. Clinical Performance and Longevity of Zirconia Restorations

Zirconia has become widely used in the modern world of restorative dentistry due to its greater biocompatibility, high mechanical strength, and durability. These properties form the basis of its application in single crowns, fixed dental prostheses (FDPs), and implant-supported restorations. Clinical performance of zirconia restorations was extensively evaluated by systematic reviews and meta-analyses that reported a high survival rate with variability associated with the type of restorations, anatomical location, and follow-up period [1,39,40]. Similar results were also documented in more general assessments of all-ceramic restorations in which both the design and the indication of the restorations significantly influenced clinical success rates. In tooth-supported fixed dental prostheses (FDPs), the survival rates with 5–10 years are generally 85–95 percent, and in the posterior areas, the performance is more reliable in the case of traditional 3Y-TZP zirconia. Retrospective clinical data also show survival rates of more than 90% with a five-year follow-up [41].
Zirconia restorations have been evaluated on a comparative basis with other types of ceramics, such as lithium disilicate. Recent retrospective cohort studies indicate that zirconia prostheses have the same survival rates with better fracture resilience in high-load situations, but lithium disilicate could offer better optical performance in anterior restorations [42,43].
Table 2 shows that zirconia restorations have high survival rates in different study designs and clinical indications, which are generally between 85 and 100 percent. The statistics indicate that single crowns and monolithic zirconia restorations are likely to have higher survival rates compared with multi-unit fixed dental prostheses and veneered systems. Moreover, tooth-supported restorations tend to exhibit more predictable performance compared to implant-supported prostheses, which is probably explained by the variations in the load distribution and biomechanical behavior. Differences in reported outcomes are mostly due to variations in zirconia production, design of restoration, and post-restoration time. In general, the data confirms the reliability of zirconia as a reliable material to be used in long-term clinical practice, while emphasizing the necessity of choosing the type of restoration and material structure to address the functional requirements. The difference in reported survival rates indicates the heterogeneity between studies, and it occurred due to differences in restoration design (crowns versus fixed dental prostheses), type of support (tooth-supported versus implant-supported), generation of zirconia, and length of follow-up. Monolithic zirconia restorations and tooth-supported crowns have a higher survival rate than veneered systems and multi-unit prostheses.
Preparation design greatly affects the clinical outcomes of zirconia restorations. In the case of monolithic zirconia crowns, the axial reduction of about 0.8–1.0 mm and the occlusal reduction of 1.0–1.5 mm are typically recommended, depending on the type of zirconia and the clinical indication. The reduction can be more substantial in the anterior areas to maximize translucency. Shoulder finish lines are desired to be chamfered or rounded, to reduce stress concentration and for marginal adaptation [2,44].
The reliability of bonding is also important in long-term success, as indicated by the above clinical outcomes. Due to the chemical inertness of zirconia, adhesion relies upon surface treatments, including airborne-particle abrasion in combination with phosphate-containing primers (e.g., 10-MDP), which significantly enhances bond strength and retention of zirconia restorations [35,45,46].
Clinical performance might also be influenced by manufacturing. Additive manufacturing techniques, such as three-dimensional gel deposition, have been investigated recently and show encouraging increases in fracture strength compared with milling technology. But these findings are still preliminary and need to be tested in long-term clinical studies before it will be possible to make definitive conclusions [33].
Surface finishing and occlusal adjustments are crucial for positive long-term outcomes. The proper polishing retains the surface integrity and decreases the occurrence of microcracks. Zirconia that has been well polished has shown to result in significantly less wear to opposing enamel than rough or glazed surfaces, which highlights the importance of post-adjustment polishing processes [31].
In general, zirconia restorations have better clinical outcomes, including high survival rates, good wear behavior, and high biocompatibility. It is expected that further development of zirconia composition, multilayer construction, surface treatment processes, and digital manufacturing processes will enhance their clinical reliability and durability.

6.1. Clinical Decision-Making Guidelines for Zirconia Restorations

Recent reviews based on clinical recommendations have highlighted the need to tailor evidence-based decision-making to include the position of the tooth, the state of the occlusal loading, and individual risk factors to maximize the clinical use of zirconia materials [47].

6.1.1. Tooth Location-Based Selection

High-strength zirconia (i.e., 3Y-TZP) is recommended in the case of posterior restorations (e.g., molars, multi-unit fixed dental prostheses) because of its better fracture toughness and occlusal force resistance. On the other hand, zirconia materials like 5Y-PSZ or 6Y-PSZ (high-translucency) are used in anterior restorations and present better optical characteristics without compromising mechanical performance at reduced functional loads [2,7].

6.1.2. Occlusal Load Considerations

Zirconia materials with the highest mechanical reliability are required in patients who have high levels of occlusal forces, such as those with bruxism or parafunctional habits. Monolithic 3Y-TZP zirconia is preferred in such situations because of its transformation-toughening process, and it is resistant to crack propagation. Conversely, zirconia with high translucency ought to be used carefully in high-load applications because an increase in cubic phase content reduces the fracture toughness [2,4].

6.1.3. Restoration Type and Span

Single crowns generally have better survival rates than multi-unit fixed dental prostheses (FDPs), and monolithic zirconia restorations are generally more reliable than veneered systems due to the absence of the risk of chipping. In the case of long-span prosthetic, zirconia (3Y-TZP or multilayer hybrid systems) with high strength is recommended to achieve structural stability [1,39].

6.1.4. Patient-Specific Risk Factors

The choice of the material should also be influenced by the conditions of the individual patients. High-translucency zirconia or multilayer zirconia systems are better applied to patients with high aesthetic expectations, i.e., when anterior restorations are needed. Bigger zirconia formulations (3Y-TZP) must be used in patients who have had restoration failures, heavy occlusion, or limited interocclusal space. Moreover, zirconia has certain benefits over patients who are allergic to metal, as it has a high biocompatibility rate [45,48].

6.1.5. Implant vs. Tooth-Supported Restorations

Zirconia restorations that are teeth-supported generally produce more predictable outcomes compared to those that are implant-supported, due to differences in the load distribution. In the case of restorations that are anchored on implants, careful choice of materials and occlusal planning is necessary to reduce stress foci and mechanical complexities [19,40].
Table 3 transforms scientific evidence in the field of material science into clinical action. According to the table, 3Y-TZP zirconia is always recommended in situations where there is a significant level of occlusal loading, like in posterior rehabilitation, bruxism and long-span prostheses due to its high fracture resistance. On the other hand, high-translucency 5Y-PSZ and 6Y-PSZ are mainly used in anterior restoration, in which esthetic considerations are paramount and the functional loads are relatively low. Hybrid multilayer zirconia systems provide a solution with a compromise between strength and translucency in one restoration to increase versatility. In general, the choice must balance mechanical requirements and aesthetics and take into consideration patient-specific risk factors, instead of one material in all clinical scenarios.
In short, the use of zirconia must be performed with a mixed approach: zirconia must be used with a greater focus on mechanical strength in the high-load areas of the posterior teeth, and with a greater focus on translucency and esthetics in anterior applications. When these characteristics are combined into a single restoration, these hybrid multilayered zirconia types can show a potential solution that will aid in accommodating more patient-oriented treatment planning.

7. Limitations, Controversies, and Comparison with Other Indirect Aesthetic Restorative Materials

Although significant progress has been made in the development of zirconia crowns, many limitations and controversies continue to exist about their mechanical properties, bonding strength, aesthetic qualities and clinical longevity. One of the most common and well-known limitations is the balance between translucency and mechanical strength. A prominent and widely discussed constraint is the trade-off between translucency and mechanical strength. Enhancing translucency by increasing yttria content raises the cubic phase fraction, but this simultaneously diminishes the transformation-toughening mechanism that underpins high fracture resistance. As a result, highly translucent zirconia materials, such as 5Y-PSZ and 6Y-PSZ, display lower fracture toughness than conventional 3Y-TZP zirconia, potentially restricting their use in high-load posterior restorations [2,4,7].
As mentioned in Section 6, bond reliability remains one of the key factors of long-term clinical outcome; however, its optimization is still debated due to the inconsistency in surface treatment and cementation procedures. These techniques significantly increase bond strengths and retention, but are technique-sensitive, and contamination of surfaces can adversely affect clinical outcomes [35,45].
Moreover, low-temperature degradation (LTD), also known as hydrothermal aging, has been associated with the long-term stability of zirconia. This can be achieved through the gradual transformation of tetragonal grains of zirconia to the monoclinic form in the presence of moisture and medium temperature, leading to the surface roughening and possible formation of microcracks. Nevertheless, the clinical importance of LTD is still dependent on the material. Although the tendency of traditional 3Y-TZP zirconia is more prone to such transformation, modern high-yttria zirconia (5Y-PSZ and 6Y-PSZ) exhibits insignificant vulnerability to LTD because the cubic phase is predominant, and it is thermodynamically stable and not subjected to transformation under hydrothermal conditions [2,6,7]. Therefore, the results of LTD cannot be generalized to all zirconia generations. Although the optical advancement in Section 5 has been explained, there are still some limitations to its optical characteristics. As much as high-translucency zirconia materials have a higher level of light transmission, they do not necessarily mimic the optical depth, fluorescence and opalescence of glass ceramics in challenging anterior restorations. Thus, lithium disilicate ceramics can still be a better choice in situations when the best optical performance of the enamel is needed [2,41].
Several features of zirconia restorations remain controversial in the literature, which mirror different experimental outcomes and clinical interpretations. One of the key debates is the clinical relevance of low-temperature degradation (LTD), with previous studies giving priority to the negative effect of this process on long-term mechanical stability, whereas the recent findings have shown that the modern zirconia formulations are highly resistant to this degradation. The best cementation protocol is another controversial question: in some studies, adhesive bonding with MDP-containing systems is advised, but in other studies, using traditional cementation can be satisfactory based on the design of preparation and mechanical retention. Moreover, the wear of zirconia in contact with opposing enamel is not completely resolved. Despite the early warnings of over-wear of enamel owing to the hardness of zirconia, more recent studies show that highly polished zirconia surfaces wear considerably less than rough or glazed surfaces, highlighting the need to follow proper finishing and polishing regimens [2,31].
In comparison to other indirect aesthetic restorative materials, zirconia has its particular benefits and shortcomings, as highlighted in Table 4. These comparisons show the current trend in the research of restorative biomaterials, which is focused on the attainment of the balance between the functional durability and esthetic integration [49]. Compared to lithium disilicate, zirconia shows significantly greater flexural strength and fracture resistance, which means that it is particularly suitable for posterior crowns and fixed dental prostheses. Nevertheless, lithium disilicate has a better translucency and bonding property because of the glass–ceramic microstructure that allows the etching of hydrofluoric acids and the adhesive bond strength [50]. Zirconia has significantly greater mechanical strength and fracture resistance than feldspathic porcelain, whereas feldspathic porcelain offers a better optical depth and esthetic layering. Compared to metal–ceramic restorations, zirconia offers better esthetic appearance due to its lack of metals and high biocompatibility; however, metal–ceramic systems still show good long-term clinical outcomes, particularly in the high-load areas [1,4].
Despite the benefits of wear of polished zirconia as highlighted in Section 6, its behavior with opposing enamel is controversial, particularly in various clinical settings and surface treatments. To this end, proper finishing and polishing procedures are crucial to achieving positive clinical results in the long term [31].
Overall, zirconia crowns represent an important development of modern prosthodontics, due to their high strength, good aesthetics, and long-term clinical results. Nonetheless, close attention to the choice of materials, appropriate bonding techniques, and appropriate surface finishing is needed to maximize clinical performance. Moreover, existing controversies suggest that the clinical performance of zirconia restorations depends on material composition, surface treatment, and applied clinical protocols, rather than their inherent limitations.
Table 4 compares some of the commonly used indirect restorative materials in terms of their mechanical properties and aesthetic characteristics. Zirconia displays the best mechanical properties and longevity, making it the material of choice for posterior crowns and fixed partial dentures. In comparison, lithium disilicate has higher translucency and bonding ability, so it can be used in more aesthetic anterior restorations. Feldspathic porcelain is still limited to low-stress applications because of its low fracture strength, and metal–ceramic restorations have predictable long-term performance with poor aesthetics. Resin-based and hybrid ceramics are helpful in enhancing handling and repairability, but with lower long-term durability. These differences help highlight the importance of the selection of material as an integration of mechanical, esthetic, and clinical needs.

8. Future Perspectives and Research Directions for Zirconia Restorations

Despite significant advances in zirconia material and digital fabrication technology, there are significant gaps in the existing evidence base that need to be filled to maximize the clinical performance and long-term reliability of zirconia restorations.
One of the research priorities is the long-term and properly designed clinical trials to test the modern zirconia systems, especially focusing on high-translucency (5Y-PSZ and 6Y-PSZ) and multilayer zirconia systems. Even though short- to medium-term outcomes seem promising, there is a lack of clinical data with follow-up of over 10 years. Future studies ought to standardize outcome measures, such as the survival rates, nature of complications, and patient-reported outcomes, to facilitate a meaningful cross-study comparison [7,18,39].
The other critical area that requires standardization is that of low-temperature degradation (LTD). Current research utilizes heterogeneous experimental environments, which differ in terms of temperature, humidity, and aging time, making it difficult to compare across studies. Further studies are needed to develop standard in vitro and in vivo tests to assess the hydrothermal aging and its clinical significance, especially in various generations of zirconia [2,6,24].
The perfect cementation protocol refinement remains an important field of study. Even though enhanced bond strength is observed in MDP-based adhesive systems, the most effective surface treatment and cementation approach in different clinical contexts remains unknown. Evidence-based guidelines need to be determined through comparative clinical trials of adhesive versus conventional cementation, and long-term durability of bonded interfaces [34,35,45].
In addition, more studies are needed to comprehend the wear behavior of zirconia restorations and their wear behavior in contact with opposing enamel. Even though recent research has indicated that polished zirconia has minimal impact on the antagonist wear, variations in surface finishing, occlusal adjustment, and material composition can have an impact on clinical outcomes. Prolonged clinical studies that relate surface roughness to enamel wear are necessary to make uniform finishing guidelines [2,31].
In terms of the materials science perspective, further studies in this area should focus on the microstructural engineering approaches to overcome the inherent trade-off between translucency and mechanical strength. Designs like gradient microstructures, grain size distribution, and yttria content can be used to achieve an improved combination of optical and mechanical properties in new zirconia materials [2,7,37].
The advent of digital dentistry and artificial intelligence (AI) is also a potential research direction. Modelling of stress, thickness of prosthesis, and occlusal forces, potentially aided by AI-powered CAD/CAM systems and digital twins, may allow more individualised and optimised designs. But these technologies require further clinical studies to evaluate their clinical performance and long-term durability [11,32].
In addition, the creation of bioactive and multifunctional zirconia surfaces is an emerging field. Such modification can be performed through techniques like laser activation, plasma activation, and nano-coatings, which can improve bonding and biointegration. Specifically, the use of bioactive agents such as hydroxyapatite or multifunctional platforms such as zeolite coatings has shown promise to enhance the antimicrobial and ion-release characteristics of zirconia, thereby increasing the bioactivity of zirconia restorations [37,52].
Finally, future research should focus on newer processing technologies, including additive manufacturing and advanced sintering techniques, to increase microstructure homogeneity, reduce processing time, and increase mechanical properties. These technologies are promising, but their potential needs to be assessed in systematic studies [25,33].
In summary, future research on zirconia restorations should focus on more stringent standardization of test methods, clinical long-term verification, and development of multifunctional materials. This trend is in line with the modern biomaterials studies, which are aimed at transferring the principles of advanced ceramics into practical restorative systems used in the clinic [29,53], so that the next generation zirconia systems will be characterized by an improved mechanical performance, aesthetics, and biocompatibility in the framework of contemporary prosthodontics in summary, as in Figure 7, which shows new research directions and technology.

9. Conclusions

Zirconia has become a multifunctional restorative material with increased mechanical strength and aesthetic performance. Available evidence shows that clinical success is not merely about the material properties, but also about the proper selection of cases, restoration design, and surface treatment regimen. The traditional 3Y-TZP has better fracture resistance and can be used in the posterior and high-load bearing areas, whereas 5Y-PSZ (high-translucency zirconia) would be more appropriate in the anterior restorations where esthetics is a priority. Monolithic designs and adequate polishing are significant to improve long-term results by decreasing the chipping and wear of the opposite dentition. There are still some issues with bonding durability, the trade-off between translucency and strength, and long-term performance of new generations of zirconia, despite favorable survival rates. Future studies ought to focus on clinical validation over time, standard testing procedures, and the creation of superior zirconia systems that combine optimized microstructure and digital manufacturing technologies to enhance predictability and clinical dependability.

Funding

This research received no external funding.

Data Availability Statement

The data set used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Key factors influencing the development of zirconia dental restorations.
Figure 1. Key factors influencing the development of zirconia dental restorations.
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Figure 2. Major advances in the development of zirconia in dentistry.
Figure 2. Major advances in the development of zirconia in dentistry.
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Figure 3. Dental zirconia (yttria-stabilized) structural schematic diagram and classification.
Figure 3. Dental zirconia (yttria-stabilized) structural schematic diagram and classification.
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Figure 4. CAD/CAM system fabrication of crown-bridge restorations.
Figure 4. CAD/CAM system fabrication of crown-bridge restorations.
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Figure 5. Innovations in manufacturing techniques for zirconia crowns (A) Pre-sintered zirconia crown after CAD/CAM milling, showing the initial fabrication stage, (B) Fully sintered and polished zirconia crown placed on a dental model, illustrating the final restoration with improved strength and translucency.
Figure 5. Innovations in manufacturing techniques for zirconia crowns (A) Pre-sintered zirconia crown after CAD/CAM milling, showing the initial fabrication stage, (B) Fully sintered and polished zirconia crown placed on a dental model, illustrating the final restoration with improved strength and translucency.
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Figure 6. Digital workflow and manufacturing stages of zirconia restorations (A) Digital model of zirconia restorations. (B) Milled zirconia bridge before sintering, showcasing the pre-finalized form. (C) Final sintered zirconia restoration showing completed surface characteristics and translucency.
Figure 6. Digital workflow and manufacturing stages of zirconia restorations (A) Digital model of zirconia restorations. (B) Milled zirconia bridge before sintering, showcasing the pre-finalized form. (C) Final sintered zirconia restoration showing completed surface characteristics and translucency.
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Figure 7. Future directions in optimizing zirconia restorations for dentistry.
Figure 7. Future directions in optimizing zirconia restorations for dentistry.
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Table 1. Comparison of zirconia generations.
Table 1. Comparison of zirconia generations.
GenerationYttria ContentDominant Phase CompositionStrength (MPa)Fracture Toughness (MPa·m1/2)TranslucencyRecommended ApplicationsReferences
1st Gen (3Y-TZP)3 mol%
Y2O3		Predominantly tetragonal~1000–12008–10LowPosterior crowns, long-span bridges (FDP frameworks), implant abutments[18,21]
High-Translucent 3Y-TZP3 mol% Y2O3 (reduced alumina)Tetragonal with improved optical phase distribution~900–11006–8ModerateMonolithic crowns, short-span bridges[18,25]
2nd Gen (4Y-PSZ)4 mol%
Y2O3		Mixed tetragonal–cubic~800–10004–6Moderate–HighMonolithic crowns, anterior and posterior restorations[2,26]
3rd Gen (5Y-PSZ)5 mol%
Y2O3		Increased cubic phase (~40–50%)~600–8002–4HighVeneers, anterior crowns, esthetic applications[2,26]
Ultra-Translucent Zirconia (6Y-PSZ)6 mol% Y2O3Mostly cubic phase~400–6002–3Very HighHighly esthetic anterior restorations[2]
Polychromatic Multilayer Zirconia (Uniform Composition: M3Y, M4Y, M5Y, M6Y)Same yttria throughout blockSame phase composition across layers~700–11004–8Gradient color translucencyMonolithic crowns with natural shade gradient[27]
Hybrid Multilayer Zirconia (e.g., M3Y–5Y, M3Y–4Y, M4Y–5Y)Mixed (3Y–5Y)Layered tetragonal–cubic gradient~700–11004–8Variable (incisal high translucency)Full-contour crowns, full-arch prostheses, esthetic monolithic restorations[2,27]
Table 2. Summary of clinical studies on zirconia restorations.
Table 2. Summary of clinical studies on zirconia restorations.
StudyDesignParticipants (Studies/Patients)Restoration TypeSupport TypeFollow-UpSurvival RateKey Notes (Heterogeneity)
[39]Meta-analysis30+ studies (~1000+ pts)FDPsTooth-supported3–10 yrs85–95%Variation due to zirconia type and design
[1]Systematic review 40 studiesMultiple-unit FDPsTooth-supported5yrs~94% survivalHigher complication rates in all-ceramic FDPs compared with metal-ceramic FDPs
[40]Review of systematic reviewsMultiple reviewsFDPs and crownsTooth + ImplantLong-term85–95%Complication variability (chipping, failure)
[41]Retrospective studyClinical cohortCrowns and FDPsTooth-supported5 yrs>90%Higher survival in single crowns
Table 3. Evidence-based clinical selection of zirconia materials.
Table 3. Evidence-based clinical selection of zirconia materials.
Clinical ScenarioRecommended ZirconiaSupporting Evidence
Posterior molars, high load3Y-TZP[2,4]
Anterior crowns5Y-PSZ/6Y-PSZ[2,7]
Bruxism/high occlusal force3Y-TZP (monolithic)[2,4]
Esthetic multilayer crownsHybrid multilayer zirconia[7]
Long-span FDPs3Y-TZP/hybrid zirconia[1,39]
Implant-supported restorationsHigh-strength zirconia (3Y-TZP)[40]
Table 4. Comparison of zirconia and other indirect aesthetic dental restorative materials.
Table 4. Comparison of zirconia and other indirect aesthetic dental restorative materials.
MaterialAesthetic PropertiesMechanical StrengthClinical PerformancePatient Acceptance and BiocompatibilityAdvantagesDisadvantages/LimitationsReferences
Zirconia (3Y–6Y, monolithic or multilayer)Moderate-high translucency; multilayer zirconia provides improved shade gradientsVery high strength (≈700–1200 MPa for 3Y-TZP; lower for highly translucent zirconia)>90% survival (5–10 yrs)High biocompatibility; low plaque accumulation; high patient satisfaction reported in clinical studiesHigh fracture resistance; suitable for posterior crowns and bridges; durableBonding more complex; translucency still lower than glass ceramics; strength decreases as translucency increases[2,4,39]
Lithium Disilicate Glass CeramicVery high translucency and enamel-like optical propertiesModerate strength (≈360–500 MPa)~85–95% survival (5–10 yrs)Excellent soft tissue response; high esthetic satisfaction in anterior restorationsExcellent esthetics; strong adhesive bonding capabilityLower fracture resistance than zirconia; limited use for long-span prostheses[50]
Feldspathic PorcelainExcellent translucency and natural optical depthLow strength (≈60–120 MPa)Limited to veneersHigh biocompatibility; favorable gingival responseSuperior optical appearance; ideal for veneersVery brittle; high fracture risk under functional loads[2]
Metal–Ceramic (Porcelain Fused-to-Metal)Good esthetics but limited translucency due to metal frameworkVery high mechanical strength>95% survival (10–15 yrs)Good biocompatibility; lower patient acceptance in esthetic zones due to metalReliable mechanical performance; suitable for bridgesDifficult detection of secondary caries; gray margins; possible metal allergy[4]
Resin-Matrix Ceramics/Hybrid CeramicsGood translucency and polishabilityModerate strength (≈150–250 MPa)Acceptable short-medium termGood patient comfort; elastic modulus similar to dentinEasy milling and repair; conservative preparationsLower wear resistance and strength compared with zirconia or lithium disilicate[51]
Indirect Composite ResinsAcceptable esthetics but limited translucencyLow-moderate strengthModerate longevity; mainly for conservative restorationsGood patient comfort; repairableEasy adjustment and repairHigher wear and discoloration; lower long-term durability[51]
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Mohammed, S.F.; Yhaya, M.F.; Al-Rawas, M.; Noorani, T.Y. Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance. Ceramics 2026, 9, 50. https://doi.org/10.3390/ceramics9050050

AMA Style

Mohammed SF, Yhaya MF, Al-Rawas M, Noorani TY. Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance. Ceramics. 2026; 9(5):50. https://doi.org/10.3390/ceramics9050050

Chicago/Turabian Style

Mohammed, Sohaib Fadhil, Mohd Firdaus Yhaya, Matheel Al-Rawas, and Tahir Yusuf Noorani. 2026. "Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance" Ceramics 9, no. 5: 50. https://doi.org/10.3390/ceramics9050050

APA Style

Mohammed, S. F., Yhaya, M. F., Al-Rawas, M., & Noorani, T. Y. (2026). Advances in Zirconia Crowns: A Comprehensive Review of Strength, Aesthetics, Digital Manufacturing, and Clinical Performance. Ceramics, 9(5), 50. https://doi.org/10.3390/ceramics9050050

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