Clinical effectiveness of Zirconia versus titanium dental implants in anterior region: an overview of systematic reviews

Abstract

Background

Nowadays dental implants are commonly used and to fulfil esthetic demands, zirconia has been suggested as an implant material as an alternative to titanium. Many researchers and systematic reviews are documented on it, but the results have been often inconsistent. This overview of systematic reviews aimed to report on the factors that influence the clinical effectiveness of zirconia (Zi) versus titanium (Ti) dental implants in anterior region.

Methods

This overview of systematic reviews (Registration Number CRD42023396206) is in accordance with the Transparent Reporting of Systematic Reviews and Meta-analyses. PubMed, Cochrane, Scopus, Embase and Google Scholar databases were sourced for systematic review and meta-analyses. Joanna Briggs Institute (JBI) criteria and Measurement Tool to Assess systematic Reviews” (AMSTAR-2), evaluated the quality. The PICO-focused question of this overview of systematic reviews was “What are the various factors influencing the clinical performance of Zi versus Ti implants in the anterior area?”, Evaluations were assessed by two assessors. In case there was any uncertainty or dispute among the reviewers, the work was included for further screening. Using Cohen's kappa, the inter-reviewer reliability was evaluated.

Results

Six reviews were chosen from 57 suitable reviews for this data analysis. Although the survival and effectiveness rates backed titanium implants, there was no conclusive proof of marginal bone loss. Zirconium implants performed better in terms of aesthetics.

Conclusion

Clinical performance of zirconia could be considered at par with titanium implants in the anterior area. Titanium has exhibited greater mechanical performance but no significant difference between two recorded. In future, studies with improved design are needed to identify biological and technical factors that affect implant’s efficacy.

Novelty and relevance

This is the first overview of systematic reviews focusing specifically on the anterior region, evaluates both aesthetic and biomechanical performance of Zi and Ti Implants, offers detailed insight into material-specific advantages and limitations. In the present clinical scenario it addresses a critical gap by comparing the performance of Zi and Ti implants and evaluates patient-centred priorities, particularly in the highly visible anterior region.

Introduction

A frequent and reliable method of restoring missing teeth is dental implants [1]. Studies have shown that they had higher success rate (ScR), with long-term ScR ranging from 90 to 98% over 10 years of use [2, 3]. ScR can vary depending on various factors, like patient bone quality, the placement of the implant, and the patient's overall oral hygiene [4]. Dental implants often use zirconium (Zi) and titanium (Ti). Both demonstrate good clinical performance, but there are some differences in their properties and how they perform in the oral environment [5].

Ti dental implants have been used for over 50 years and have a proven track record of success. They have a high ScR and are considered to be unsurpassed in implant materials used in dentistry [6]. Ti is biocompatible and highly resistant to corrosion and wear. It also has good osseointegration properties, which means that it can fuse with the surrounding bone tissue and create a strong bond [7]. Ti comprises of various purity degrees (grades I to IV). Following Ti as being frequently employed, apart from these, alloys of Ti, aluminum and vanadium are also utilized due to its durability and biocompatibility [8,9,10,11].

Zi dental implants are a newer option and have been gaining popularity in recent years. Zi is a ceramic material that is highly biocompatible and has excellent esthetic properties [12]. Zi implants have a white color that can blend in with the natural teeth, making them a good option for patients with thin or translucent gums. Zi is also highly resistant to corrosion and wear, making it a durable component in them [13].

Literature observes that Ti as well as Zi dental implants have high ScR. However, there are some differences in their performance in certain situations [14,15,16,17,18]. Few studies have found that Zi implants may have a slightly higher risk of fracture compared to Ti implants, especially in areas of the mouth with high biting forces [19,20,21]. Duan et al. reported that in Zi implants high failure chances due to their mechanical weakness [18] and Morena [22] concluded that. Ti dental implants have a better survival rate and less marginal bone loss than Zr dental implants after 1 year follow-up. Additionally, some research has suggested that Zi implants could show higher implant failure risk in early stages of osseointegration compared to Ti implants [16]. Advantage of Zi implants is that they are more aesthetically pleasing than Ti implants, especially in areas where the implant is visible [20]. Zi implants may also be a better option for patients who have allergies to metals or who had a higher probability of forming metal allergies [21].

Overview of systematic reviews can reach a broader area than regular systematic reviews or meta-analyses by comprehensively surveying the available high-quality evidence. Although comprehensive under certain conditions, they are meticulously designed analysis as potential comparative effectiveness stokes guidelines we suggest to apply and for an effective comprehensive strategy on a given topic. According to our knowledge, no published overview of systematic reviews among the general dentistry cohort has concisely examined the present situation and clinical usage of zirconia dental implants and compared their effectiveness with titanium counterparts. As the topic is broadly covered in the field of dentistry, such an overview of systematic reviews seems worthwhile to be carried out.

Dental implants made of titanium are currently the most frequently used fixtures in implantology and have proven their long-term clinical efficacy [23]. The main reasons for their success are attributed to excellent osseointegration and ability to endure occlusal loads. Despite that, concerns regarding potential esthetic limitations in the anterior region drove the exploration of metal-free materials, like zirconia, among researchers and clinicians [24]. Zirconium dioxide implants were originally designed as an alternative for patients allergic to titanium or concerned about sensitivity to metal. However, the given implants—alike their predecessors, ceramics and carbon implants of the past decades—posing a controversial alternative to titanium, due to relatively poor mechanical properties. As the demand for zirconia dental implants keeps growing and there is a proven interest in this topic, it seems important to summarize the available literature under the overview of systematic reviews that have the potential to guide clinicians towards the most appropriate solutions.

Overall, both Zi and Ti dental implants are feasible tooth replacement choices for patients. Though many evaluations have been published, no clear proof is available with respect to clinical performance of implant substances as it is dependent on variables such as general health, implant placement, and cosmetic preferences. This overview of systematic reviews aimed to compare clinical performance of Zi versus Ti dental implants in the anterior area.

Materials and methods

The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) 2020 statement was employed to execute our the overview of systematic reviews (SR), as it has widespread acceptance, comprehensive structure, and emphasis on transparency and rigor. This overview of systematic reviews was conducted in accordance with Cochrane Handbook for Systematic Reviews of Interventions. This overview of SRs was registered with International Prospective Register of Systematic Reviews (PROSPERO) (Registration Number CRD42023396206). The PRISMA 2020 statement was employed to ensure transparency and rigor in reporting, as recommended by Moher et al [25]. PRISMA provides a structured approach to documenting literature searches, inclusion criteria, and data synthesis, thereby minimizing bias and enhancing reproducibility.

• Focused question

The PICO-focused question of this overview of systematic reviews was “What are various factors influencing the clinical performance of Zi versus Ti implants in the anterior area?”, focusing on:

P-Population: Healthy or diseased patients with dental implants in anterior region

I-Intervention: Zirconia or Zirconium oxide implant

C-Comparison: Titanium implant

Outcomes: Any relevant outcome of clinical performance but not limited to; implant survival rate (ISR), ScR, marginal bone loss (MBL), peri-implant soft tissue status, and biologic and functional complications of implants.

Data extraction was conducted using a pre-designed form based on the PICO framework (Population, Intervention, Comparison, Outcome). The PICO framework is a well-established approach in evidence-based medicine for structuring research questions and synthesizing data systematically [26].

• Inclusion and exclusion criteria

The criteria for the study inclusion were as follows: Systematic reviews with or without meta-analysis evaluating the analyzed outcomes of Zi and Ti implants. The exclusion criteria were as follows: Systematic review of in vitro studies, systematic reviews of animal studies, studies focused on the implant–abutment interface, studies comparing titanium and zirconia abutments and it clinical effect. Other forms of studies such as randomized control studies, case reports, laboratory studies, uncontrolled trials, duplicate reviews, comments, and editorials were excluded. Studies not meeting the inclusion criteria were excluded.

• Search Strategy

A comprehensive search of the literature was done from inception to January 15, 2025, including PubMed, Scopus, Embase and Google Scholar for systematic reviews with or without meta-analyses (MA).

There were three steps in the approach that were followed for gathering systematic data. Step 1: Two impartial reviewers evaluate and filter the data. Reviewers first examined the titles of the papers they had gathered, either electronically or manually. Step 2 comprised of examining the abstracts. The two reviewers then looked over the entire texts of the papers in step 3. In case there was any uncertainty or dispute among the reviewers, the work was included for further screening. The third evaluator then made final decision. The PRISMA 2020 Flow Diagram presented in Fig. 1 shows the method of data selection (represented in Supplementary table 1). Using Cohen's kappa, the Inter-reviewer reliability was evaluated. The K values were found for Google Scholar (K=0.82), Ebsco Host (K=0.81), and PubMed (K=0.82).

• Screening method

Fig. 1

PRISMA flowchart for the process of study selection

Two independent reviewers (S.M.A and V.M.) scanned these databases using text terms and Medical Subject Headings (MeSH) terms in the absence of any language barriers. In the search algorithm, the following keywords were used (“Titanium”[Mesh] OR “Zirconium” OR “Zirconia oxide”] AND (“Dental implants” [Mesh] OR “Crowns” [Mesh] OR “Dental Prosthesis” [Mesh]).

Following the procedure set for data collection, the number of retrieved citations was noted, and duplicates were removed. The two reviewers (S.M.A. and V.M.) independently reviewed all the studies that were initially found through electronic searches. The full texts were then acquired and examined for potential inclusion and exclusion. Studies that failed to meet the requirements for inclusion were discarded. Any disagreements were resolved through discussion or by consultation of third reviewer (S.C.). The included articles were manually snowballed for any further SRs alone or without MA that might be significant. Contact with authors was done in case of missing or insufficient information.

• Data extraction

Two assessors extracted pertinent data from selected studies separately with a pre-designed data gathering form, and any inconsistencies were sorted by deliberation among the assessors. Basic information of studies (study ID, title, authors,), participants, intervention, comparison, search details (search method, databases), range of studies selected, sources searched, type of studies selected, appraisal (appraisal rating, tool employed), results (list of outcomes, results of study), significance of review and heterogeneity were the major elements of the data extraction.

• Quality assessment

For evaluating the methodological quality of this SR’s with or without MA, we used the JBI critical appraisal checklist for SRs [27]. There were 11 questions to guide appraisal of SR or MA. Every question was answered as “yes”(Y), “no”(N), or “unclear”(U). Not applicable “NA” was also an option. Scores were assigned for conformance to each of the 11 questions, with a min of 1 and a max of 11 indicating a well-conducted review. The two reviewers made decisions on research quality and eligibility, and any ambiguities were settled through discussion or by consultation of third reviewer (S.C.). The JBI critical appraisal checklist was utilized to evaluate the methodological quality of included systematic reviews (Table 1). This tool is widely recognized for its ability to assess the reliability and validity of evidence across various study designs, as highlighted by Munn et al. [28]

Table 1 Risk of bias assessment by Joanna Briggs Institute (JBI) evaluation checklist

Also, table 2 presents the appraisal tool “Measurement Tool to Assess systematic Reviews” (AMSTAR-2). AMSTAR 2 is a rating system that focuses on specific domains, encompassing seven essential domains and nine additional non-essential domains. Rather than producing a single total score, AMSTAR 2 assesses the overall quality by examining performance across both critical and non-critical domains, with each category receiving different levels of importance according to the established rating criteria, as previously used by Li et al. [29] Two reviewers, conducted an independent assessment of each study included in the review using the AMSTAR 2 online checklist. Any disagreements that arose during this process were resolved with the assistance of a third reviewer, who referenced the original AMSTAR 2 publication, its supplementary materials, and relevant sections. The critical and non-critical domains evaluated are presented in Table 2, with seven falling into critical criteria and nine into non-critical ones. The findings for all 16 domains were documented, with each response categorized as either “yes” or “no” based on AMSTAR 2 guidelines. If a more than 2 domains received a “no” response, it was deemed “low.”

Table 2 Quality assessment of included SRMAs using AMSTAR 2

Results

The flowchart of the process of selecting articles is as shown in Fig. 1. The original search in PubMed, Scopus, Embase and Google Scholar yielded 1669 studies. Following an evaluation of the duplicate records, 215 were removed and 1454 studies were chosen for screening. After examining the title, abstract, and inclusion/exclusion criteria, 1395 papers were excluded. A total of 59 full-text papers were reviewed for eligibility, with 53 of them being irrelevant. Ultimately, the overview of systematic reviews included six studies [14,15,16,17,18, 22]. Thus, a total of 6 research articles from the selected reviews, were considered for the evaluation.

All included reviews explicitly mentioned the review subject in the title, abstract, or body. Average quality score of these selected systematic reviews was 9 ± 1.58. The research sources, evaluation standards, and independent appraisal were all suitable in 75% (4) of the reviews. In addition, techniques for reducing errors and publishing bias were not addressed in 25% (2) of the studies. For 50% (3) of the reviews, the techniques used to combine papers were suitable.(Table 1).

The critical appraisal of included studies using the AMSTAR2 method revealed that two [16, 22] of them had critically low levels of evidence, while the remaining four [14, 15, 17, 18] had low levels of evidence (Table 2). The critical areas of flaws were usually because of not providing the list of excluded studies (3/6), non-reporting of funding sources (5/6), and non-reporting of publication bias (3/8).

Database sources utilized in the selected reviews were minimum of 2 and maximum of 5. Tables 3 and 4 summarize basic and clinical characteristics of the selected reviews.

Table 3 Baseline characteristics of systematic reviews

Table 4 Clinical characteristics of systematic reviews

Comisso study selected using Cochrane Central Register of Controlled trials and MEDLINE via Pub-Med [14]. Elnayef study inspected with MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Cochrane Oral Health Group Trials Register [15]. Fernandes studys creened in MEDLINE/PubMed and Web of Science, whereas Sales study extracted from Medline, Central Cochrane, Scopus, LILACS and Google Scholar [16, 17]. Apart from these databases, to ensure comprehensive search, all the studies had performed manual search of the references from the included studies or the dental journal. Duration for which literature was screened was available in all the selected reviews. Comisso study and Fernandes study selected studies from 2010 to 2020 [14, 16]. Elnayef study included studies till 2015, Duan reported studies from 2014 to 2021 [18], Sales involved till 2022 [15, 17] and Morena 2014–2024 [22] (Table 3).

Both retrospective and prospective studies were part of the selected reviews. Randomized clinical trials (RCTs), Cohort and case series were evaluated. Fernandes study reviewed 7 RCTs, Sales study reviewed 3 RCTs, however, in Comisso study, out of 15 articles, 5 articles were prospective cohort studies, 3 articles retrospective cohorts, 2 retrospective case series, 2 RCTs and 3 prospective case series, whereas in Elnayef study, among the 21 articles, 5 prospective cohort studies, 8 prospective case series and 4 RCTs and 4 retrospective clinical studies, Duan study contained 4RCTs with 6 with six records [14,15,16,17,18].

The participants in Comisso study were partially edentulous in the upper-anterior sextant, Elnayef study, Fernandes study and Sales study studied comprised of partial or completely edentulous healthy patients acquiring one or more implants. The intervention group in Comisso et al., Elnayef study and Sales study papers were Zi implants, whereas Fernandes study included Ti–Zi implants along with Zi implants. Comparator group in all the studies were Ti implants. The Duan study comprised of total of 109 participants with 248 implants with both Zi and Ti implants comparison [14,15,16,17,18].

Among the outcome parameters assessed in these reviews, Comisso study mainly included aesthetic benefits along with clinical benefits such as white and pink aesthetic scores, peri-implant, crown indices, bleeding on probing (BOP) plaque index (PI), and probing depth (PD), MBL, papilla height, ISR and ScR; while Duan study included success rate, marginal bone loss (MBL), and probing pocket depth (PPD); secondary outcomes included plaque index (PI), bleeding on probing (BOP), pink aesthetic score (PES), and reasons for failure. The study design (S) of interest was randomized controlled trials (RCT) [14,15,16,17,18].

Elnayef study considered clinical benefits that contained ISR, ScR and MBL [15]. Apart from these, confounding factors were also assessed. Whereas Fernandes, Duan and Sales study included clinical benefits similar to Elnayef study BOP, PD and confounding factors that is implant features and patient habits were also included by Fernandes study [15,16,17,18].

Evaluation of quality of RCTs was done with Cochrane collaborations’ tool in all studies, and other than RCTs was done with Newcastle–Ottawa Scale [30]. The majority of the studies examined by Comisso study did not compare Ti implants to Zi implants, but rather examined the attributes of Zi dioxide implant [14]. Hence, the study design was not consistent. Duan included studies comparing the Zi and Ti implants. He reported that the success rates were downgraded to moderate, the survival rate, PPD, BOP, and PES were low, and the MBL and PI were very low. Eighteen of the selected articles in Elnayef review were discarded as they had no comparison between Zi implants and Ti implants [15].

Table 4 summarizes the major results (clinical aspect) of the systematic reviews. The number of papers that comprised those systematic reviews ranged from 3 to 21. There were 2020 participants in total from all the four reviews, as the gender and age differentiation were not available for Elnayef study and Sales study had 329 males and 339 females with an average 54.45 years of age, with a follow-up ranging between 12 and 84 months [14,15,16,17]. Duan study had total of 109 subjects with 248 implants [18] and Morena study had 6 RCTs; 152 patients (90 males and 62 females) and 448 implants (267 Zi and 181 Ti).

Ti implants showed better ISR than Zi implants in 75% of reviews. According to current research, conventional all-Ti implants had a longer ISR, whereas all-Zi implants have a short ISR. Elnayef study concluded that ISR of Zi was considerably lower than Ti [15]. Comisso study found a statistically insignificant variation between the two categories [14]. Regardless of the follow-up time, all trials examined by Fernandes et al. resulted in higher ISR with Ti compared to Zi [16]. According to Sales study Ti has a higher ISR percentage than Zi [17]. While Sales' total ISR was poor, compared to other systematic reviews [17].

Our findings indicated that systematic studies primarily led to Ti implants showing greater ScR than Zi implants. Elnayef study conducted a comprehensive analysis and discovered a statistically insignificant difference for Zi and Ti implants ScR [15]. Morena et al. [22] reported in their review that Ti dental implants have a better survival rate and less marginal bone loss than Zr dental implants after 1-year follow-up. Fernandes study and Sales study both found similar findings in their comprehensive reviews [16, 17]. In comparison, a study by Comisso study found Zi to be superior to Ti, but the difference was statistically negligible [14]. However, in terms of aesthetics, both Zi and Ti were similar, in few studies’ Zi was better than Ti. Ti implants were found to be superior in terms of peripheral MBL in 75% of reviews. Elnayef reported higher MBL for Zi [15]. In Comisso study, no conclusive evidence is obtained regarding MBL [14]. MBL of Ti and Zi implants remained constant in follow-ups of the papers reviewed by Fernandes study but, all the study had a short follow-up time [16]. Significant difference in MBL was reported by sales study that favoured Ti implants [17]. As an outcome, no definitive evidence pertaining the MBL was obtained in the present comprehensive analysis.

Discussion

With the growing number of recently published systematic reviews, an evaluation of these reviews is an essential next step in providing a high-level evidence base for clinical practice. This overview of systematic reviews was conducted to summarize the findings of systematic reviews and meta-analyses investigating clinical endpoints of zirconia dental implants. This is the first comprehensive review of this type which compared the efficacy of Zi and Ti dental implants in the anterior area. By conducting an overview of systematic reviews, we would like to less the bias and variance in the adopted literature sources and evidence. This motivation is consistent with what Ioannidis et al. noted for evidence-based medicine: observable associations do not identify causal ones, overwhelmingly, suggests that surprising and challenging results often suffer from the high bias and the low-positive prediction value. By this limitation, we searched electronically and manually and could retrieve only 4 articles based on inclusion and exclusion criteria. This caused a smaller sample size. Still, this could show clinical efficacy of Zi and Ti dental implants in the anterior area.

The results of this overview of systematic reviews demonstrate that zirconia implants offer a viable treatment modality for replacing missing teeth in the anterior region. Notably, zirconia implants exhibit similar marginal bone loss to titanium implants for a single restoration with good patient satisfaction, sufficient survival and success rates, and comparable prevalence of peri-implant diseases compared to titanium implants [31]. An important point to underscore is that zirconia implants were more often associated with mechanical and technical complications compared to titanium implants. This overview of systematic reviews revealed a longer treatment time and possibly greater prosthodontic complications with zirconia implants despite no significant difference in implant survival between the two materials.

A study from Linkevicius et al., 2015 was excluded in the present study as the review considered only soft tissue biotypes [32]. Another systematic review by Cao et al., 2019 was also excluded as it was focused on the implant–abutment interaction specifically, the survival rate of titanium implants with zirconia abutments and clinical trials reporting the effects of implants with zirconia abutments [33].

Comisso study identified 1109 papers, after removing duplicates 1104 were screened, of which 633 were evaluated as suitable, but after full text screening only 15 were chosen for the final analysis [14]. Elnayef study identified 193 studies, 117 were screened, and 58 were found eligible, out of which 21 were eligible for analysis [15]. Fernandes study identified 415 records, but 217 were duplicates, so 198 were screened for eligibility and 7 were eligible and included for analysis [16]. Sales study identified 3235 articles,and eliminated 3211 were eliminated at the screening stage, 24 articles were assessed for eligibility, and 3 RCTs were considered for analysis [17].

In paper by Comisso study Zi dioxide implants had higher ScR and ISR, ranging 50% to 100% which could be because heterogenic studies in all reviews or a variation of the time for estimating the ScR and ISR [14]. Elnayef study found Zi implants ScR was 91.6 percent [15]. There were no significant variations about efficacy of Zi and Ti implants. Even though Zi implants do not have as much history as Ti implants. Dental implants made of Ti have an exceptionally high ScR (96.4%) over 10 years, in contrast to 87% and 100% ISR from the latest literature on Zi implants, where post evaluation period ranged from one to eight years [34].

Analysis in Elnayef review revealed the mean ISR for Zi ones was 74.8% (OR = 1.89; 95% CI 1.00–3.56), substantially lower than mean ISR for Ti implants (85.7%) [15]. Zi implants have an 89% higher failure rate than Ti implants. Following a mean post op period of 42.37 months, Zi implants had a 91.5% ISR and a 91.6% ScR, according to the Elnayef study MA [15]. After 12 and 21 months, Andreiotelli study demonstrated a ISR of 98% and 84%, respectively [35]. In Fernandes review, ISR for Zi was 87.5–91.2%, for Ti-Zi 95.8–100%, and for Ti 92.6–100% [16]. Ti implants outperformed Zi implants in terms of ISR. Ti-Zi implants have a similar ISR to Ti implants but a higher ISR than Zi implants. Ti-Zi implants were taken into consideration since they are a mixture of both of the materials that were researched and typically consist of 85% Ti and 15% Zi, which enables a direct comparison. These findings need to be supported by research conducted over extended time periods with extensive follow-ups. According to studies, Ti implants have ISR of over 95% after 10 years; therefore, Ti is preferred as the primary implant material [36,37,38]. In Sales review, ISR of Ti (87.4%) was better than Zi (78.1%), however, with a statistically insignificant variance [17]. One potential explanation for the paradox is the mechanical weakness of Zi implants. Narrow implants have worse ISR than standard-diameter implants [39]. However, the increased rate of failure could be attributed to the research approach instead of the material.

Survival rate is a fundamental parameter for the evaluation of the clinical performance and acceptance of different implant biomaterials. In our overview of systematic reviews, survival rate ranged from 65.0 to 100.0% for Zirconia implants and 90.0 to 100.0% for Titanium implants. This result indicates that both Titanium and Zirconia implants have high stability in the anterior part of the dental arch after a 1–5 years follow-up period. Good survival rate is an essential standard to evaluate the clinical use of Zirconia implants, which could decrease concerns due to the premium price of the material. The Duan reported the ISR of Zi implants as 92.77, 98.58, and 86.38% at one, two and five follow-up years, respectively, while the success rate was 84.89, 80.78, and 66.38%, respectively [18].

There is a visible display of the metal components due to MBL and minor recession of tissue [40]. However, it is stated that it was related to the cementation [14, 41,42,43]. Radiographic bone loss is not clearly reported by Comisso study but overall clinical benefits support Zi [14]. In Elnayef study analysis, statistically noteworthy difference for the marginal bone loss for Zi implants (0.89 ± 0.18 mm), more compared to MBL for Ti implants (mean difference = 0.14 mm) was reported [15]. In Fernandes review, MBL for Ti ranged between 0.125–1.17, for Zi 0.25–1.38 and for Ti-Zi 0.32–0.60 [16]. Koller's research exhibited the highest MBL for Ti, which might be due to the longer duration of analysis and the method of restoration [44]. MBL of Ti and Zi implants remained constant postoperatively. Trials were noted to have shorter postoperative durations. Even though the MBL for Ti-Zi implants was similar to Ti and Zi, It ought to be mentioned that only a limited number of Ti-Zi ones were tested, which may make it difficult to draw definitive conclusions [16]. In Sales review, favorable difference was seen in Ti with respect to MBL [17]. The meta-analysis by Morena et al. [22] reported an effect size of − 0.61 (95% CI [− 0.83; − 0.39]), which was statistically significant (p < 0.001), indicating that MBL outcomes were notably lower in titanium implants than in zirconium implants across the studies reviewed. Additionally, Cochran’s Q value was found to be p = 0.59 and I [2] = 0%, leading to the conclusion that there was no heterogeneity among the studies regarding this parameter.

Zirconia is an esthetic alternative to titanium for dental implants [45]. Zirconia dental implants have shown similar clinical outcomes to titanium implants in terms of aesthetics, plaque control, and peri-implant bone level. A recent meta-analysis stated that survival rates for short Zr implants were lower than long ones but these differences were not statistically significant [46]. The success rate of Zr implants is 95 to 97%. The Morena et [22]al stated that the success of Ti implants after one year was statistically significant compared to Zi implants in the analyzed studies. Based on the results, Cochran’s Q (p = 0.77) and I2 = 0%, there was homogeneity among studies for this parameter in their review. The prevalence (12.92%) of technical complications associated with Zr implants is comparable to or lower than those for Ti implants, while biological complications are primarily caused by peri-implantitis and seem to be higher (14.1%) compared to 5 to 10% for Ti implants [47]. Most of the technical complications are screw loosening, abutment fractures, and ceramic veneer chipping. Other authors found higher technical and biological complications for Zr implants, including fracture of implant body, higher inflammation grades, and mechanical complications compared with Ti implants. Titanium implants demonstrated superior survival and success rates in most studies, underscoring their well-documented mechanical reliability and osseointegration properties [16, 22]. Despite these strengths, titanium’s esthetic limitations and potential for metal allergies necessitate exploring alternatives like zirconia. The higher failure rates and increased risk of mechanical complications with zirconia implants, as reported in the included studies [16], emphasize the need for caution when selecting zirconia for load-bearing or high-biting-force regions. In Comisso review [14], different research has found that Ti implants had lower values for pink, white aesthetics, and the peri-implant and crown index [48,49,50]. Zi implants have a superior colour perception than Ti implants, but the distinction is only noticeable in thinner, soft tissue biotypes [35, 49]. In the selected studies, different indices are reported for the aesthetic outcome. This shows the esthetic assessment’s complexity in the reviews. In vitro experiments have revealed that the texture of the implant material has a significant impact on the cells' adherence [51]. Also, it is speculated that PD around implants could be reduced if the cells adhere better [32]. Sales study reported statistically insignificant difference for pink aesthetic score [17].

Morena et al. emphasized the exceptional aesthetic qualities of zirconia implants, especially when used in cases involving thin or translucent gum types. The color of zirconia closely resembles that of natural teeth, which significantly lowers the chances of visible metal near the front of the mouth. This characteristic is vital for individuals who place a great emphasis on visual appeal, particularly in situations with noticeable smiles [18, 22]. Furthermore, zirconia is known for its biocompatibility, making it an attractive option for patients who might have sensitivities or allergies to metallic materials, thus expanding its accessibility to a larger patient base. Nevertheless, these advantages come with the necessity to consider the mechanical drawbacks of zirconia, particularly its lower resistance to fractures when subjected to significant biting forces [9]. Clinicians must also keep in mind the specific techniques required when utilizing zirconia implants. Due to its brittle composition, careful surgical and prosthetic methods are essential to reduce the likelihood of fractures occurring during installation or use.

Due to lesser affinity of the Zi dioxide surface, there was less plaque buildup, allowing for a reduced likelihood of inflammation and infections [14, 52]. Researchers discovered that Zi implants had less bacterial attachment than Ti implants, that could result in less inflammation, eventually, in a lesser cases of mucositis, peri-implantitis, or both [53]. But in Elnayef study, due to study heterogeneity, peri-implant parameters like BOP, PI, and PDs could not be statistically assessed [15]. As reported in Fernandes review, mucositis and peri-implantitis was neither reported nor noticed in the two investigations [6, 15, 53]. Three other studies did not investigate if mucositis was present [44, 54,55,56,57]. Only two investigations looked for mucositis: Ioannidis study found 10 Ti implants and 8 Ti-Zi implants afflicted, and Siddiqi study found no implants impacted [57, 58]. Five researchers looked at peri-implantitis. Koller study removed 1 Ti implant owing to peri-implantitis, whereas Al-Nawas study and Müller study removed 1 Ti and one Ti-Zi implant [44, 57, 58]. Ioannidis study reported two Ti-Zi implants with peri-implantitis, however, Siddiqi study reported no afflicted implants [57, 58]. Zi implants have a lesser bacterial affinity than Ti implants do when compared to the same conditions, also, consequently a lower occurrence of mucositis [59]. In addition, research that did not assess the occurrence of mucositis noted some limitations in the information obtained. Similar conclusions have been documented for peri-implantitis involving Ti and Zi implants in Fernandes review [16]. As reported by Pjetursson study in 2012, new surface technologies, materials, micro and macro designs, and significantly recognising variables impacting MBL and peri-implantitis, resulted in a sharp rise in Ti implant longevity (up to 97.2% after 5 years) [60]. Smoking was linked with significantly greater failure rates i.e. ISR, ScR and MBL [61]. However, patient habits were not reviewed in any of the included reviews.

The evidences regarding marginal bone level (MBL) do not provide definitive support for one type of implant material over the other. Even though the Titanium implants generally display slightly lower MBL, which may be attributed to their longer duration of use and improved surface treatments. This slight edge could also be the result of significant advancements in titanium implant surface modifications that enhance osseointegration and reduce bone remodeling. On the other hand, zirconia implants, although similar in MBL, have a notable advantage concerning peri-implant health due to their smoother surface and reduced bacterial attraction [62, 63]. These characteristics may help diminish plaque buildup and the associated risks of peri-implantitis and mucositis. Clinical evidence indicates that zirconia implants are associated with lower levels of inflammatory markers [16, 22], suggesting they may be more supportive of soft tissue health in specific situations. Nonetheless, the limited evidence on the long-term effects of zirconia implants on peri-implant health signifies the necessity for further investigation. Additionally, factors related to patients, including oral hygiene, smoking habits, and systemic health conditions, play a crucial role in MBL and peri-implant health [14]. Although zirconia implants may offer resistance to bacterial colonization, inadequate patient adherence to maintenance procedures could diminish these advantages. Therefore, educating patients and ensuring regular follow-up visits are essential for achieving optimal outcomes.

Fernandes study reviewed the failed implants throughout the follow-up period [16]. There were in total 24 Ti (8.48%), 1 Ti-Zi (1.03%), and 44 Zi (26.03%) implants reported. However, none of the other reviews taken this feature into assessment in their review. As the sample s less, they could not conclude if Ti, Ti-Zi and Zi variants had greater, similar or lower BOP. However, PD of Ti, Ti-Zi and Zi implants, on the other hand, appeared to be similar. Sales study, reported Ti and Zi showed statistically insignificant variations for BOP [17]. Height of the papilla was assessed only by Comisso study who reported an increase in height for Zi implants [14].

This current review finds statistically insignificant variations between Zi and Ti as implant materials with respect to ISR, SR, MBL and aesthetics. It is not feasible to make a conclusive analysis because of the wide range of studies. More trials are needed for assessing design impact and surface characterization of implant material on therapeutic efficacy and to uncover all the technical as well as biological variables that influence implant effectiveness and user contentment. However, clinical practitioners should consider both feasible, reliable, and cosmetic effectiveness when selecting implants.

Clinical performance of dental implants relies on several factors, like the patient's overall health, the clinician’s ability placing implants, and the patient's willingness to follow post-operative care instructions.

Limitations of the study

This overview of systematic reviews is subject to several limitations that warrant careful consideration. Firstly, the systematic reviews incorporated in this analysis display significant variability in terms of study designs, participant populations, and assessed outcomes, leading to a notable heterogeneity among the selected studies. Variations in inclusion criteria, techniques for implant placement, follow-up durations, and outcome metrics may have influenced the results and interpretations of this overview of systematic reviews.

Consequently, the findings necessitate cautious interpretation in light of this heterogeneity. Another noteworthy limitation is the relatively limited number of high-quality systematic reviews that conformed to the inclusion criteria. Despite an exhaustive search process, only a small subset of reviews was found eligible for this analysis, which could constrain the robustness and comprehensiveness of the overall findings. Additionally, the exclusion of non-English studies might result in the omission of pertinent research, thereby introducing potential language bias into the review.

A further concern arises from the predominantly short follow-up periods characterizing many of the included reviews, which may inadequately reflect the long-term performance dynamics of zirconia and titanium implants. Comprehensive long-term data concerning implant survival rates, marginal bone loss, and peri-implant health are critical to facilitate a more definitive comparison between these two materials. Moreover, a significant proportion of the studies examined in the included reviews failed to distinguish between various implant systems, designs, and surface treatments, all of which could substantially impact clinical outcomes.

Additionally, inconsistencies in the reporting of specific outcomes, such as peri-implant soft tissue health and patient satisfaction, were evident across the assessed reviews. This variability hinders the capacity to arrive at conclusive judgments regarding the overall clinical performance of zirconia as opposed to titanium implants. Furthermore, the absence of standardized criteria for aesthetic assessment complicates the interpretation of aesthetic outcomes, thereby limiting the thorough evaluation of this dimension in the review process.

Ultimately, the methodological robustness of the systematic reviews included in this analysis showed considerable variation. Certain reviews exhibited a heightened risk of bias, primarily attributable to insufficient transparency regarding their appraisal methods, the processes employed for data extraction, and the strategies implemented for synthesizing studies. This inconsistency in methodological rigor could have influenced the overall reliability of the findings articulated in this overview of systematic reviews.

Conclusion

This overview of systematic reviews concluded that –

• The clinical performance of zirconia (Zi) implants is comparable to titanium (Ti) implants in the anterior area, with no significant difference recorded between the two.

• Titanium implants demonstrate greater mechanical performance than zirconia; however, most studies do not report a significant difference in the frequency of mechanical failures.

• Marginal bone loss is not significantly influenced by the implant material.

• Decision-making should consider the benefits and drawbacks of each material, based on individual requirements and clinical scenarios.

This overview of systematic reviews provides valuable insights for clinical decision-making, considering patient-specific factors such as: Aesthetic priorities; Biocompatibility requirements; Functional demands. Potential applications of these findings include: Customized treatment planning; Development of patient education tools; Material advancements and design improvements.

In future, studies with improved design are needed to identify biological and technical factors that affect implant’s efficacy. The long-term studies including biomechanical analysis with patient-centric outcomes on aesthetic evaluations, biological responses, cost-effectiveness associated with advanced surface treatments and coatings for both zirconia and titanium implants that could yield details into improving osseointegration, reducing bacterial adhesion, and long-term clinically beneficial results.