Five‐year survival and failure patterns of complete arch fixed implant‐supported monolithic zirconia prostheses: A retrospective analysis of 3300 laboratory cases

Abstract

Purpose

To evaluate the five‐year survival rate and complication spectrum of complete arch fixed implant‐supported zirconia prostheses (CAFIPs) fabricated by a commercial dental laboratory in Dubai, UAE, aiming to identify principal modes of failure and technical challenges.

Materials and Methods

This retrospective, cross‐sectional study analyzed 3300 screw‐retained, 3Y‐TZP monolithic zirconia CAFIPs, with veneered porcelain limited to the gingival area, manufactured using standardized protocols between August 2019 and August 2024. Data on maxillary (n = 1900) and mandibular (n = 1400) prostheses, complications, reason for lab returns, and failure events were extracted from digital laboratory records. Remakes due only to technical or material failure were included. Survival analysis employed a life table approach, strictly excluding clinician‐ or patient‐driven interventions to ensure unbiased outcomes.

Results

The five‐year cumulative survival rate was 91.67%. The life span table analysis revealed a concerning trend of 2 events in year one increasing to 14 events in year five. Framework fractures (n = 38) were the leading failure cause, especially in prostheses with insufficient vertical space, while ceramic chipping (n = 4) affected mainly mandibular prostheses with excessive ceramic layering. Importantly, no cases of titanium cylinder debonding or fracture were observed, indicating mechanical reliability. Minor prosthetic complications included localized veneer chipping. Enhanced framework design and material handling were identified as improvement targets for long‐term performance.

Conclusions

Full‐arch fixed implant‐supported zirconia prostheses exhibited excellent five‐year durability. Most failures were related to framework issues or ceramic chipping, while technical problems with titanium components were absent. Continued improvements in design, manufacturing, and clinical protocols are needed to optimize longevity and patient outcomes.

The demand for highly durable, esthetic, and biologically compatible solutions for edentulous patients has led to growing interest in complete arch fixed implant‐supported zirconia prostheses (CAFIPs). ¹ Advances in materials science and digital workflows have transformed prosthodontic rehabilitation, enabling clinicians to deliver long‐span restorations that promise functional and esthetic benefits comparable to natural dentition. ² , ³

While monolithic zirconia is now widely adopted for its favorable mechanical properties, the translation of its theoretical advantages into predictable, long‐term clinical success across diverse practice settings remains a critical area of investigation. ⁴ Previous studies have reported varying survival rates for zirconia‐based prostheses, with Cinquini et al. ⁵ documenting survival rates ranging from 88% to 100% across follow‐up periods of 1–7 years. Similarly, Tischler et al. reported a cumulative survival rate (CSR) of 99.4% for zirconia prostheses, though their study was limited by a smaller sample size and shorter follow‐up period. ⁶ Bidra et al. observed a five‐year CSR exceeding 99% for monolithic zirconia prostheses but noted that framework fractures remained the primary cause of failure. ⁷ However, mechanical complications, particularly framework fractures and ceramic chipping, continue to be clinically relevant, often resulting from limited prosthetic space, unfavorable loading, or suboptimal prosthesis design. This issue has substantial implications for patient management, maintenance requirements, and cost‐effectiveness of care. ⁷

While these studies provide valuable insights, several research gaps persist in our understanding of complete arch fixed implant supported prostheses performance. Most existing investigations involve relatively small sample sizes, limiting the statistical power to detect significant differences in complication rates. Additionally, many studies lack sufficient follow‐up duration to assess long‐term performance, particularly regarding material fatigue and aging effects. There is also a paucity of research specifically examining the influence of prosthetic design variations, such as the extent of porcelain veneering, on clinical outcomes. Furthermore, most studies originate from Western populations and lack comprehensive tracking of technical and mechanical failures; consequently, there is limited data from Middle Eastern populations where anatomical variations and cultural factors might influence prosthetic performance.

As highlighted in recent reviews, there remains a need for large, retrospective studies evaluating real‐world survival and failure patterns of monolithic zirconia complete‐arch prostheses, particularly in Middle Eastern and international laboratory‐based populations.

This retrospective study was therefore designed to provide a comprehensive, real‐world assessment of CAFIP performance by analyzing a large cohort from a single, high‐volume dental laboratory in the United Arab Emirates (UAE). The specific objectives were to determine the CSR of CAFIPs over a five‐year period; identify and categorize the types and frequencies of complications encountered; analyze potential risk factors associated with prosthetic failure; and compare outcomes between maxillary and mandibular prostheses.

The significance of this study lies in its large sample size and comprehensive five‐year follow‐up, providing comprehensive data on the clinical performance of zirconia prostheses in a specific geographic population. The findings of this study can contribute valuable evidence to guide clinical decision‐making, prosthetic design, and laboratory protocols for complete arch implant‐supported restorations. Additionally, by identifying principal modes of failure and technical challenges, this research can inform improvements in materials, fabrication techniques, and clinical protocols to optimize long‐term outcomes for patients undergoing full‐arch rehabilitation with zirconia prostheses.

Therefore, the study hypothesis is that CAFIPs will demonstrate a five‐year survival rate exceeding 90%, with mechanical complications primarily associated with technical and anatomical factors, rather than material defects or component failure.

MATERIALS AND METHODS

The study protocol was reviewed and approved by the Institutional Review Board (IRB) of Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia (IRB‐2025‐02‐0760). Given the retrospective nature of the study based on anonymized laboratory records, the requirement for individual patient consent was waived by the IRB.

This retrospective cohort study was conducted at a large dental laboratory in Dubai, UAE. The study period included all CAFIPs fabricated between August 1, 2019, and August 31, 2024. The primary objective was to evaluate the five‐year CSR and characterize the spectrum of technical complications and failures.

The study sample was derived from the laboratory's complete digital database of prostheses fabricated during the specified period. Specific inclusion and exclusion criteria were applied to ensure a homogenous and relevant cohort for analysis.

Inclusion criteria:

1. Screw‐retained, complete‐arch fixed implant‐supported prostheses.

2. Prostheses fabricated predominantly from monolithic zirconia with a facial cutback for esthetic enhancement.

3. Veneered porcelain application strictly limited to the gingival region.

4. Prostheses manufactured from 3Y‐TZP (3‐mol% yttria‐stabilized tetragonal zirconia polycrystal), Dentsply Sirona HT (High Translucency) zirconia.

5. Adherence to standardized laboratory fabrication protocols involved the use of prefabricated titanium bases. Bonding to the zirconia framework was achieved through airborne‐particle abrasion of the bonding surfaces followed by the application of adhesive resin cements to ensure a stable mechanical union, as prescribed by the material manufacturer. ⁸

Exclusion criteria:

1. Prostheses remade or modified due to non‐technical reasons, such as clinician‐driven factors (shade mismatch, occlusal discrepancies, incorrect implant angulation) or patient‐driven factors (patient preference, dissatisfaction with esthetics).

2. Prostheses with incomplete digital records regarding fabrication date, arch type, or reason for return.

3. Prostheses with a follow‐up duration of less than one year, unless a failure occurred within that period.

A priori sample size calculation was performed to ensure the study was adequately powered. Using an online sample size calculator (Raosoft Inc., Herndon, Veterans Affairs, USA), with a confidence level of 95%, a margin of error of 5%, and assuming an unknown population size, a minimum sample of 385 prostheses was determined to be sufficient to estimate survival rates. The final study sample comprised 3300 prostheses, substantially exceeding the minimum required and thus providing excellent statistical power for the survival analysis.

Data Collection and Variables

Data were systematically extracted from the laboratory's proprietary digital records and warranty tracking system by a single calibrated researcher to minimize data entry errors. As all prostheses were covered by a five‐year warranty program, the laboratory provided replacement restorations to clinicians for technical or material failures identified in this cohort. This system facilitated the capture of comprehensive failure data.

For each prosthesis that met the inclusion criteria, the following variables were collected:

1. Prosthesis Demographics: Type of arch (maxillary or mandibular) and date of fabrication and delivery to the clinic.

2. Follow‐up Information: Duration in situ, calculated from the date of prosthesis insertion to the date of its return to the laboratory for any reason or to the study endpoint (August 31, 2024).

3. Outcome Variables:

   • Survival: Defined as the prosthesis remaining in situ without requiring a remake due to technical failure.
   • Failure: Defined as any catastrophic technical event (framework fracture) necessitating a complete remake by the laboratory.
   • Complication: Defined as a non‐catastrophic technical event (e.g., minor veneer chipping, titanium cylinder debonding) requiring laboratory intervention but not a complete remake.

4. Reason for Laboratory Intervention: Reasons for prosthetic return were categorized into predefined objective groups: framework fracture, ceramic/veneer chipping, titanium cylinder complications (debonding/fracture), margin chipping, and other technical failures. This categorization was designed to isolate material and technical failures from clinical or patient‐related factors.

Statistical Analysis

Descriptive statistics, including frequencies and percentages, were used to summarize the distribution of prostheses by arch type and the incidence of different complications. The primary outcome, the five‐year CSR, was calculated using a life table (actuarial) analysis. This method is particularly suitable for retrospective studies with varying entry times and censored data, as it estimates survival probability at discrete time intervals. Annual interval survival rates and CSR were calculated for each year of the five‐year follow‐up period. The analysis was performed for the entire cohort and stratified by arch type (maxillary vs. mandibular) where appropriate. All statistical analyses were performed using a standard statistical software package (SPSS version 28.0, IBM Corp., Armonk, New York, USA). A significance level (α) was set at 0.05 for all statistical tests.

RESULTS

A total of 3300 screw‐retained, full‐arch monolithic zirconia bridges with facial cutback were fabricated by the dental laboratory between August 2019 and August 2024. Of these, 1900 prostheses were maxillary and 1400 were mandibular, with survival and complication data systematically analyzed (Table 1).

TABLE 1.

Descriptive data related to 3300 complete arch fixed implant‐supported zirconia prostheses.

Failure causes	Maxillary CAFIPs (1900)	Mandible CAFIPs (1400)
Prostheses remade because of framework fracture	18	20
Prostheses remade because of chipping of ceramic	2	4
Prostheses remade because of chipping in the zirconia	0	1
Prostheses remade because of chipping in zirconia margins	2	0
Prostheses with technical complications caused by debonding of the titanium cylinder	0	0
Prostheses with technical complications caused by fractured titanium cylinder	0	0
Prostheses remade because of soft tissue recession	1	0

The life span table analysis over five years indicated a notable progression in annual failures as follows: 2 in 852 prostheses during year one, 7 in 773 during year two, 12 in 732 during year three, 13 in 511 during year four, and 14 in 432 during year five. (Table 2).

TABLE 2.

Five‐year life span table survival analysis of all complete arch fixed implant‐supported zirconia prostheses.

Time interval (y)	No. of zirconia prostheses in interval	No. of failures in interval	Interval survival rate (%)	Cumulative survival rate (%)
0–1	852	2	99.77	99.77%
1–2	773	7	99.09	98.86%
2–3	732	12	98.36	97.23%
3–4	511	13	97.46	94.73%
4–5	432	14	96.76	91.67%

Framework fracture was the most prevalent complication, prompting the remake of 38 prostheses (18 maxillary and 20 mandibular). These fractures were linked to insufficient vertical prosthetic space, impression discrepancies, and the presence of micro‐cracks during laboratory fabrication. Mandibular fractures also occasionally resulted from bone flexure. Six prostheses (two maxillary and four mandibular) were reconstructed due to ceramic layering chipping, predominantly attributed to excessive stacking. One mandibular case required a remake for a thin zirconia framework at the incisal edge, while two maxillary prostheses were remade because of margin chipping, typically arising from deep implant placements and reduced gingival height abutments used with angled screw channels. Notably, mandibular prostheses did not exhibit this complication. No technical issues were observed regarding debonding or fracture of titanium cylinders, confirming the mechanical stability of these components. One maxillary prosthesis was replaced due to significant gum recession, which precluded ceramic application.​

DISCUSSION

This retrospective study evaluated the five‐year performance of 3300 CAFIPs fabricated in a single laboratory setting. The principal finding was a CSR of 91.67%, which aligns with the study's primary hypothesis of high long‐term durability for these restorations. Consequently, the null hypothesis of the study was accepted. This large sample size, representing one of the largest cohorts reported in the literature to date, offers real‐world performance of CAFIPs across diverse clinical settings and practitioners. The most prevalent mode of failure was framework fracture, followed by ceramic chipping. Notably, the complete absence of technical complications related to titanium cylinder debonding or fracture underscores the mechanical reliability of the prosthetic components.

The 91.67% five‐year CSR demonstrated in this large cohort is clinically significant and confirms the viability of CAFIPs as a long‐term treatment modality for edentulism, especially considering the study's criteria that included only failures attributable to technical or material issues, thereby providing an unbiased assessment of the prostheses themselves. The 91.67% five‐year CSR demonstrated in this study falls within the 88%–100% range as reported by Cinquini et al., ⁵ reinforcing the general consensus on the high success of zirconia prostheses. The findings validate the growing trend toward all‐ceramic solutions in prosthodontics and support the material choice for complete arch rehabilitation. However, in the current study, the survival rate was slightly lower than the >99% rates reported by Tischler et al. ⁶ and Bidra et al. ⁷ This discrepancy could be explained by the substantial difference in sample size and study scope. The present study, with 3300 prostheses from numerous clinics, represents a more pragmatic, “real‐world” scenario that likely captures a broader spectrum of clinical challenges, including variations in surgical placement, patient selection, and impression quality. In contrast, smaller cohorts might originate from single centers or highly experienced clinicians, which may involve more stringent case selection and controlled conditions, thereby potentially inflating survival rates.

However, the fact that approximately 8.3% of prostheses failed over five years indicates that while zirconia is highly durable, it is not infallible. The data suggests that failures were predominantly related to a triad of factors: clinical execution, laboratory protocols, and the inherent material response to long‐term stress, rather than a single inherent material deficiency. A particularly concerning observation was the trend of increasing failures in the fourth and fifth years. This temporal pattern suggests the onset of material fatigue and subcritical crack growth, which are well‐documented phenomena in brittle ceramic materials under sustained cyclic loading. This finding warrants a cautionary warning: the five‐year survival rate of 91.67% may not be indicative of the long‐term (10‐year or greater) performance. Clinicians should be aware of this potential for late‐term failures and incorporate this into patient counseling and maintenance protocols. This trend emphasizes the need for even longer‐term surveillance studies to fully understand the aging behavior of these large‐span prostheses.

The identification of framework fracture as the principal cause of prosthesis failure (38 cases) warrants a detailed examination of its etiological factors. The findings suggest that insufficient vertical prosthetic space is a critical predisposing factor, often stemming from the clinical phase of treatment. When the occlusal‐gingival dimension is limited, the zirconia framework must be fabricated thinner to accommodate restorative space, compromising its flexural strength and resistance to fatigue under cyclic masticatory loads. This aligns with the principles of materials science and engineering, where the thickness of a brittle material is directly proportional to its load‐bearing capacity. ⁹ This explanation is supported by Skjold et al., who emphasized the critical relationship between zirconia thickness and fracture resistance in laboratory studies of dental crowns. ¹⁰ Furthermore, the data point to laboratory fabrication errors, such as the introduction of micro‐cracks during milling or sintering, and clinical inaccuracies like impression discrepancies, as significant contributors. These flaws act as stress concentration points, from which fractures can propagate under functional load. ¹¹ In the mandibular arch, the unique phenomenon of bone flexure during function may also contribute to non‐axial loading of the rigid prosthesis, ¹² further increasing the risk of fracture, a concept related to the complex biomechanics discussed by Vinhas et al. ¹³ regarding implant‐abutment connections. This aligns with the retrospective studies by both Bidra et al. ⁷ and Tischler et al., ⁶ who also found that framework fracture was the most significant technical complication. This consistency across different study designs and populations strengthens the conclusion that framework integrity is the Achilles' heel of CAFIPs.

Ceramic chipping, while a less frequent complication (8 cases), presented a distinct pattern, primarily affecting mandibular prostheses with excessive ceramic layering. This finding is consistent with previous studies on the vulnerabilities of bilayered all‐ceramic systems. ¹⁴ The chipping occurs due to a combination of factors, including the inherent brittleness of the veneering porcelain, the thermal coefficient of expansion (CTE) mismatch with the zirconia substructure, ¹⁵ and the development of tensile stresses within the veneer, especially in areas of high functional demand like the mandible. ¹⁶ Labis et al. highlighted ceramic chipping as a notable complication in complete‐arch zirconia restorations. ¹⁷ The lower incidence of this complication reported here, compared to previous studies, may be directly attributed to the prosthetic design philosophy, which utilized a predominantly monolithic zirconia structure with porcelain veneering strictly limited to the gingival area. This approach minimizes the volume of the weaker veneering material, thereby reducing the overall risk of chipping, a conclusion supported by previous studies. ¹⁸ , ¹⁹ , ²⁰

The complete absence of prefabricated titanium cylinders debonding or fracture is a remarkable observation that refers to the efficacy of the standardized bonding protocol including; the airborne‐particle abrasion of the titanium/zirconia interface followed by application of an MDP‐containing adhesive resin cement. ²¹ This protocol ensures a durable micromechanical and chemical bond between the titanium base and the monolithic zirconia framework capable of withstanding long‐term masticatory forces. However, this contrasts with some earlier studies that occasionally cited this as a technical issue. ²² , ²³ Calderon et al. ²⁴ reported that debonding at the titanium/zirconia was a frequent complication; however, this was related to suboptimal titanium base geometry.

While this study included a large sample size and a five‐year observation period, some limitations must be acknowledged when interpreting the results. The analysis was confined to information available in the laboratory's digital records, which, while comprehensive for technical outcomes, lacked crucial patient‐level variables. Factors such as parafunctional habits, smoking status, bone quality, oral hygiene compliance, and individual occlusal forces, known significant confounders for prosthetic survival, could not be assessed. The single‐laboratory, single‐material nature of the study may affect the generalizability of the findings. All prostheses were fabricated using 3Y‐TZP HT zirconia and according to one laboratory's specific protocols. The outcomes might differ with other zirconia compositions or fabrication techniques in different laboratory settings.

CONCLUSION

Within the limitations of this retrospective study, it can be concluded that CAFIPs demonstrated a favorable five‐year CSR of 91.67%, confirming their viability as a long‐term treatment modality for edentulism. Framework fracture was the predominant mode of failure, often associated with insufficient vertical prosthetic space, impression discrepancies, and micro‐cracks introduced during laboratory fabrication. The increasing trend of failures in later years warrants a caution regarding potential material fatigue over the long term. Ceramic chipping, while less frequent, was a significant complication, particularly in mandibular prostheses with excessive porcelain layering. The zirconia‐titanium cylinder interface demonstrated excellent mechanical reliability, with no instances of debonding or cylinder fracture observed throughout the study period. The long‐term success of CAFIPs is highly dependent on meticulous prosthetic design, precise clinical execution, and controlled laboratory protocols to mitigate technical failures.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.