Clinical Performance of Endocrowns in Molars: A Scoping Review

1. Introduction

Endodontically treated teeth (ETT) are scientifically documented to be more susceptible to fracture than vital teeth. This is attributed to their significant loss of tooth structure, resulting from procedures such as caries removal, access cavity preparation, root canal preparation, irrigation, and the use of intracanal medicaments [1,2,3,4]. This process exposes the tooth to irreversible physicochemical and biomechanical changes, including dentin dehydration, collagen disruption, and reduced microhardness, conditions that compromise both structural integrity and proprioception [1,5]. Therefore, maintaining as much healthy tooth structure as possible is crucial for the long-term survival of ETT [3,6,7]. This statement is endorsed by studies demonstrating that EETs present an 80% higher risk of restoration failure compared to vital teeth [8].

Clinicians experience challenges when restoring ETT due to the increased functional and parafunctional loadings that occur on posterior teeth, which contribute to a higher risk of restoration failure [1,9]. ETT restored by post-and-core crowns exhibit higher rates of root fractures, particularly when no circumferential ferrule is obtained. Furthermore, the absence of ferrule in conjunction with the extensive removal of dentin in the core of the root canals facilitates the debonding of fiber-reinforced posts. The presence of short roots and limited restorative space is a factor associated with restoration failures [5,10]. The limitations associated with traditional restorative approaches, along with recent advancements in adhesive dentistry and dental biomaterials, have driven the development of evidence-based alternative modalities for the restoration of endodontically treated teeth (ETT) [2,3,5,9,10,11,12,13,14,15,16,17,18,19,20].

Pissis in 1995 first introduced the monobloc technique, described as a laboratory-fabricated core and crown unit designed as a single component [17]. This concept was further developed by Bindl and Mörmann in 1999, who used the term “endocrown” to describe a mono-block ceramic crown bonded to a devitalized posterior tooth [21]. The survival of these one-piece endodontic crowns is achieved through macro-mechanical retention, which serves as an anchorage for the restorative material, providing stability, and micro-mechanical retention via adhesive cementation, forming a strong bonding interface between the restoration and the tooth surface while minimizing microleakage [7,11,12,18,22]. Endocrowns have gained prominence as a minimally invasive technique compared to conventional post-and-core crowns, particularly for molars. Their anatomical design promotes minimal invasive preparation [2,12,16,23] and confines catastrophic failures commonly associated with posts [2,3,5,6,9,18,24].

Factors affecting the survival and success rates of endocrowns include, among others, the material type used and the preparation design, with emphasis on the finish line, occlusal reduction, and extension into the pulp chamber. The extent to which each factor influences the performance of endocrowns needs further investigation. While systematic reviews have focused on specific aspects such as materials or survival rates [2,7,11,12,16], the available literature on endocrown restorations remains diverse in scope, methodology, and outcomes. Given this heterogeneity and the emerging nature of adhesive and restorative techniques, a scoping review is warranted to provide a broad mapping of current evidence, clarify key concepts, and identify gaps for future research. The objective of this scoping review is to investigate and summarize the most recent data on the application of endocrowns for restoring severely damaged posterior ETT, focusing on comparing the clinical performance of endocrowns to that of post-and-core restorations, identifying the most appropriate materials and preparation techniques, and highlighting areas where additional research and standardization are needed.

2. Materials and Methods

The reporting of this review followed the recommendations of the latest PRISMA for Scoping Reviews (PRISMA-ScR) statement [25], to ensure methodological transparency and systematic reporting. The PCC (Population, Concept, Context) framework was adapted to structure the research question and facilitate the selection process (Figure 1).

2.1. Sources of Information and Search Strategy

A comprehensive search of the literature was conducted using the following electronic databases: MEDLINE through PubMed and Scopus, covering publications from inception to March 2025. The search strategy for all databases was based on the term “endocrowns” solely or combined with other keywords such as “endocrowns AND materials”, “endocrowns AND ferrule”, “endocrowns AND survival rate”, and “endocrowns AND post-and-core restorations”. Additional relevant studies were identified by manually screening the reference lists of all included articles and related reviews.

2.2. Eligibility Criteria

The search results were filtered by language, and articles published in English were eligible. The scoping review included systematic reviews, meta-analyses, umbrella reviews, literature reviews, in vitro studies, randomized controlled clinical trials, and retrospective clinical studies. Research studies on anterior teeth or premolars, as well as case reports, letters to the editor, patents, short communications, and conference abstracts were excluded to maintain the clinical relevance and quality of evidence within the defined scope.

2.3. Data Extraction, Screening, and Charting

The study selection process was conducted in two stages. First, titles and abstracts were screened by two independent reviewers (A.K.Z and K.T.) to identify potentially eligible studies. In the second stage, full-text articles were retrieved and assessed by the pre-established inclusion and exclusion criteria. In the presence of disagreements screening was conducted by a third reviewer (E.P.) until consensus was reached. Data charting was performed using a standardized extraction form created and implemented by the reviewers. To ensure consistency, all reviewers pre-tested the form on a sample of studies and refined it through discussion before proceeding with the complete data extraction. Each reviewer independently extracted data, and all charted items were cross verified to ensure accuracy. The information collected was organized into two Tables. The first table summarizes the results of systematic reviews and meta-analyses, synthesized descriptively, and categorizes thematically based on comparisons between endocrowns and post-and-core crowns, material selection, and survival and success rates. The second table reported the results of eligible literature reviews, umbrella reviews, in vitro studies, retrospective studies, and RCTs, giving an insight into clinical performance and long-term outcomes of endocrowns, preparation design, cementation processes, mechanical properties, and material selection. The table of systematic reviews and meta-analyses included author and year of publication, main objectives, search strategy and data screening information, and key findings, whereas the second Table included author and year of publication, study type, main objective, study design, and key findings. No assumptions or simplifications were made during this process.

Given the nature and purpose of scoping reviews, no formal critical appraisal of the included studies was performed. However, study type, study design, and methodological rigor of each study were considered during data synthesis and interpretation.

3. Results

A total of 1,406 articles were identified through comprehensive searches conducted in the MEDLINE database via PubMed and Scopus. After record removal due to duplicates, records not published in English language, lack of relevance (e.g., anterior teeth), ineligible study types (e.g., case reports, letters, short communications, conference abstracts), insufficient focus on posterior ETT, lack of direct evaluation of endocrowns to post-and-core restorations, or failure to meet design criteria, a total of 37 articles were included in this scoping review. The selection process is outlined in Figure 2.

The included studies were categorized into two primary groups based on study type and are reported in Table 1 and 2. All systematic reviews and meta-analyses (11 articles) [2,6,7,11,12,16,23,24,26,27,28] are included in Table 1, which were thematically subcategorized as described in the “Methods and Materials” section.

Table 2 reported 20 original research studies – including fifteen in vitro studies, three RCTs, and two retrospective clinical studies – and six reviews (umbrella narrative and literature reviews). These studies were categorized according to their main subject of interest: Ten studies evaluated the clinical performance and long-term out-comes of endocrowns [1,8,10,14,29,30,31,32,33,34], six studies focused on the preparation design and cementation procedure applied [15,18,35,36,37,38] , four studies examined the mechanical strength and load resistance influenced by material and preparation design [4,13,39,40], and six studies compared the different materials that are available for endocrown restorations [19,20,41,42,43,44].

A common area of interest among the included studies was the mechanical behavior of endocrowns – particularly fracture resistance – which was commonly evaluated under simulated masticatory conditions. Fifteen articles specifically compared endocrowns with traditional post-and-core crowns [6,8,10,13,19,23,24,26,27,29,30,31,34,37,40], while six articles compared them to other types of restorations, highlighting differences in performance outcomes [1,4,14,19,20,41] . In ten studies, the influence of restorative material on functional durability was investigated, by comparing materials such as lithium disilicate, zirconia-reinforced lithium silicate, and resin-based ceramics [2,11,16,20,28,32,33,39,42,43]. Additionally, ten studies examined the decisive role of preparation design on the final performance of endocrowns, evaluating the impact of pulp chamber depth and ferrule presence on the integrity of the final restoration [7,12,15,16,18,35,36,38,42,44]. Marginal adaptation described as a critical aspect in preventing microleakage and enhancing long-term durability was appraised in five articles [12,15,16,36,38].

4. Discussion

4.1. Key Findings of This Scoping Review

4.1.1. Clinical Indications: When and Why to Choose Endocrowns

Based on the research results, endocrowns are primarily indicated for restoring posterior ETT with substantial structural loss, particularly when post-and-core methods are not feasible [13,29,41]. Therefore, endocrowns are suitable for molars with short, obliterated, calcified or divergent roots, where conventional posts may pose clinical challenges [2,9,10,12,13,15,18,29,41]. Additionally, they are recommended for restoring teeth where an adequate ferrule effect cannot be achieved and where interocclusal space is insufficient [2,9,10,12,13,18,29,41,45]. In such cases, conventional post and core crowns may fail to provide adequate material strength, thickness, and structural support, making endocrowns a more reliable treatment modality [13]. Traditional crown preparation may require the removal of 67.5–75.6% of the tooth tissue, whereas the decay-oriented design of endocrowns facilitates the preservation of tooth viability [16,38]. Simultaneously, there is no need for post-preparation into the root canals, which has been associated with an increased chance of vertical fracture [9]. The micro- and macro-mechanical retention of endocrowns relies on the adhesive cementation and stability derived from an adequate pulp chamber for bonding [8,16]. El Ghoul et al.’s findings correlate with other studies, which indicate that endocrowns provide superior fracture resistance compared to post-and-core crowns due to their single-piece design, which minimizes internal stresses and enhances strength through improved occlusal thickness, while preserving peripheral enamel for better adhesion and load distribution [40].

Thus, endocrowns are best suited for molars with extensive coronal damage, limitations in root anatomy, or reduced interocclusal space, especially when preserving tooth structure is a clinical priority.

4.1.2. The Impact of Cuspal Reduction and Intracoronal Extension on Retention and Fracture Resistance.

To ensure the longevity of endocrown restorations, efforts have been made over the years to develop proper preparation guidelines and design protocols through numerous clinical and laboratory studies. It is essential to emphasize the potential for preparation and design modifications based on individualized clinical conditions [14]. Most recommendations focus on parameters such as cuspal reduction and occlusal thickness. While no standard line on these parameters has been established, based on the majority of eligible studies, the cuspal reduction ranges between 2-3 mm [6,15,16], with Dartora et al. suggesting a slightly broader range of 1.5 to 3 mm [41]. Otto et al. demonstrated that greater occlusal thickness in endocrowns is related to increased fracture resistance, emphasizing on the mechanical advantage of thicker restorations [14,34]. While increased occlusal thickness generally enhances fracture resistance, Taha et al., and Mostafavi et al. agreed that aggressive preparations should be avoided, as these could compromise tooth structure without providing desirable clinical benefits [16,46]. Notwithstanding, it is important to consider that other factors may influence cuspal reduction, including tooth type, interocclusal space, cavity depth, remaining axial wall thickness, and the restorative material used [16,20]. Therefore, an occlusal thickness of approximately 3 mm is generally recommended to optimize fracture resistance but ashould be carefully modified based on anatomical and material-related factors to prevent excessive tooth reduction.

In general, the occlusal thickness of endocrown restorations typically ranges between 3 mm and 7 mm [20,23,46], including the cuspal reduction and the intracoronal extension [5]. Adequate pulp chamber depth is essential for macro- and micro-mechanical retention [9,10,11,22,26,35]. It is crucial for the preparation not to extent the pulpal floor through the radicular orifices, as a more complex preparation can result in insufficient marginal and internal adaptation, ultimately compromising the long-term performance of the final restoration. [5,16,24,26]. Although there is no consensus on the exact chamber depth, Zhang et al. observed that while increasing chamber depth from 1 mm to 3 mm led to higher stress on the restoration, the stress on tooth tissue remained relatively stable, except for a noticeable increase at the root furcation with 3-mm depths, particularly under horizontal loading. It was interesting to note that the 2-mm depth exhibited the best stress distribution, which was the least concentration on the restoration and on the surrounding tooth tissues[47]. This is in agreement with Hayes et al. who found that deep extensions greater than 2 mm were factors that increased the probability for catastrophic failures under oblique forces [48]. Dartora et al., however demonstrated that the mechanical resistance of the restoration depends on the extent of the pulp chamber extension, which contributes to improved stress distribution of masticatory forces and increased resistance [10,22,35]. They also emphasized that when the pulp chamber depth is only 1mm, the restoration is prone to rotational motion [10,16,35]. Thomas et al. agrees with the fact that very shallow chambers (<2 mm) may lead to debonding, which could lead to reducing the success of the endodontic therapy due to coronal microleakage [9]. Veselinova et al. strengthened this conservative approach by using a 2-mm depth for their investigation and stating that there was no significant difference between 4-mm and 2-mm depths, but deeper extensions tended to fail more seriously[20]. Alqarni et al. found that an intracoronal depth of 2 mm provided greater fracture resistance. However, a 4 mm depth resulted in more catastrophic, non-repairable fractures, while 0 mm showed failure patterns similar to those of untreated teeth [49]. Overall, these findings suggest that while both underextension and overextension carry risks, a 2-mm pulp chamber depth may provide the best balance between retention, stress distribution, and clinical safety.

The retention of the restoration depends on the surface available for adhesion; thus, smaller pulp chambers lead to higher failure rates and debonding [7,11,13,20,21,23,26]. When endocrowns have a disadvantageous height-to-width ratio, greater leverage forces are generated, and a higher risk of restoration displacement due to adhesive rupture may occur [10,13,23,26]. In the molar region, the orientation and concentration of axial forces play a critical role in the clinical performance of endocrowns [6,23]. Another important factor is the relationship between bone height and the pulp chamber floor, which significantly influences the mechanical behavior of the restoration. Ribeiro et al. [18] demonstrated that when the pulp chamber floor is positioned above the crestal bone level, the risk of mechanical failure increases due to unfavorable stress distribution. Clinically, achieving an adequate pulp chamber depth and maintaining a favorable height-to-width ratio are essential to reduce debonding and stress concentrations—particularly in molars and in cases with limited bone support .

4.1.3. Pulp Chamber Cavity Preparation: Balancing Retention, Resistance, and Bond Strength

In addition to considerations related to the pulp chamber cavity, meticulous internal preparation is essential to ensure accurate placement and optimal adaptation of the final restoration. [10,16]. A flat surface floor with an axial wall divergence of approximately 6 degrees without undercuts but with rounded angles, increases precision in internal fit [5,16,41]. To further optimize clinical outcomes, the immediate dentin sealing (IDS) technique using flowable composite resins can be employed to cover irregularities in the pulp chamber walls [5,10]. This approach not only eliminates retentive zones that hinder the adjustment of the restoration but also improves adhesion to dentin, reduces microleakage and strengthens the bond in ETT where dentin adhesion is weaker than enamel [3,5,10,11,29]. Additionally, the cementation protocol plays a critical role in the performance of endocrowns, as optimal adhesion between the restoration and tooth structure directly influences stress distribution and fracture resistance [23]. Inadequate cementation may compromise micromechanical retention, increasing the risk of debonding [5,7]. Resin cements are the material of choice due to their excellent bonding capabilities, color adaptability, adequate mechanical properties, and resistance to dissolution [5]. However, polymerization shrinkage poses drawbacks including an increased risk of microleakage, resulting in a higher susceptibility to adhesive failure, especially when marginal gaps or insufficient retentive height occur. These conditions aggravate stress accumulation at the tooth-cement interface [7,36]. Thus, optimal internal preparation, use of immediate dentin sealing, and careful resin cementation are essential to prevent microleakage, improve retention and minimize stress at the tooth-restoration interface in endocrown restorations.

4.1.4. The Effect of Finish Line Design on Flexural Strength, Stress Distribution, and Internal Adaptation

Another major factor influencing the clinical outcome of endocrown restorations is the finish line design [7,50]. The circumferential 90-degree butt-joint margin, typically 1–2 mm in width, remains the most commonly used configuration. However, several studies have shown a growing preference for shoulder finish lines and the incorporation of a ferrule effect [5,6,15,16,24,38].

The shoulder margin design has been associated with improved flexural strength and stress distribution compared to the butt-joint margin [16,46,50,51]. Incorporating a ferrule—a short axial wall in the cervical area—acts as a bracing mechanism, enhancing both structural integrity and the surface area available for adhesion [1,13,16,23,26,28]. Einhorn et al. [15] reported that a 1 mm ferrule significantly reduced the incidence of irreparable fractures compared to a 2 mm ferrule or no ferrule. Similarly, Taha et al. [46] recommended the preconditioning of a short axial wall with a shoulder finish line to improve mechanical strength. In situations where a ferrule is absent, Mostafavi et al. and Govare et al. [16,26] suggested adding a beveled margin to enhance adhesive potential. Zeng et al. [38] evaluated stress distribution among butt-joint, 90-degree shoulder, and 135-degree shoulder designs. While the general stress patterns were similar, the 135-degree shoulder demonstrated lower stress concentration and improved biomechanical viability.

Cervical margin placement should also be carefully considered. Supragingival positioning is preferable [6,10,15,24,26,41], particularly for preserving enamel near the cementoenamel junction, which is essential for optimal bond strength [16,23,26,38]. In such scenarios, the butt-joint margin may be advantageous as a less invasive technique—preserving tooth structure, offering resistance to compressive forces, and reducing marginal leakage [16,38,46]. Taha et al. [46] demonstrated that CAD/CAM polymer-infiltrated ceramic endocrowns—whether with a butt-joint or shoulder margin—can resist forces exceeding typical axial masticatory loads in the molar region, which generally range between 600–900 N [20], with some studies reporting up to 850 N [46]. Interestingly, Einhorn et al. [15] noted that the simpler preparation associated with butt-joint designs may lead to better internal adaptation compared to configurations incorporating a ferrule.

To sum up, while the butt-joint margin remains a minimally invasive and effective option, shoulder finish lines with short ferrules may enhance fracture resistance and stress distribution Individual anatomical characteristics, enamel availability, and material choice should all be taken into consideration when choosing a margin in clinical practice.

4.1.5. Choosing the Right Material: Mechanical and Esthetic Considerations in Endocrown Performance

The advancement of biomaterials has introduced new indirect restorative materials with an elastic modulus like that of dentin, while simultaneously providing superior fracture resistance. It is well known that the elastic modulus of enamel and dentin is 84,1 GPa and 18,6 GPa, respectively [36]. As the restoration's physicomechanical characteristics get closer to that of the dentin, the risk of catastrophic fractures decreases [26]. The monoblock design of endocrowns, which minimizes material interfaces, improves stress distribution compared to conventional post-and-core restorations that combine materials with different elastic moduli [9,23]. Several studies have compared lithium disilicate-based ceramics (LD/LDS/LDSB) or lithium disilicate glass ceramics (LDGC) with different types of zirconia (monolithic zirconia, zirconia-reinforced lithium silicate/ ZLS), indirect resin-based materials (RB), or resin nanoceramics (RNC) in terms of restoration's adaptation, bond capacity, fracture resistance, optical and biomechanical properties, biocompatibility, and wear (Table 3).

Lithium disilicate based ceramics have been considered as the material of choice for endocrown restoration due to their superior adhesive properties and resistance to displacement [2,13,40]. Strong bonding is achieved through micromechanical “interlocking” between the etchable ceramic material and the resin cement, enhancing the stability of the restoration [13,26,35,40]. Additionally, its high esthetic quality and superior fracture resistance make it a promising choice for dental applications [26]. However, there are several limitations associated with LDS. The high elastic modulus of lithium disilicate ceramics, approximately 90GPa, often increases the risk of tooth fractures, which could result in irreparable fractures under excessive stress [19]. Furthermore, the material’s stiffness may induce wear on opposing natural teeth, while its brittle nature often results in restoration failure due to porcelain fracture [2,11].

Monolithic zirconia has a modulus of elasticity above 200 GPa, which is significantly higher than that of dentin and thus is prone to catastrophic failures [42]. When Veselinova et al. examined monolithic zirconia and CAD/CAM lithium disilicate endocrowns, they found that the latter exhibited higher fracture strength and less catastrophic failures compared to the former, which mainly fractured beneath the cementoenamel junction [20,52]. When Alwadai et al. examined the lithium disilicate glass ceramics versus zirconia-reinforced lithium disilicates for optimal marginal adaption, they found that both were within the range of values deemed clinically acceptable [12]. An in vitro study by Kumar et al. showed that endocrowns made from monolithic zirconia exhibited a larger internal gap compared to those made from lithium disilicate (LDS) [53]. In contrast, Falahchai et al. found that zirconia endocrowns exhibited superior marginal and internal fit compared to LDS and ZLS, with the most significant gaps consistently observed in the pulpal area and the smallest at the margins [54].

Zirconia-reinforced lithium silicate (ZLS) ceramics combine zirconia’s mechanical strength and the aesthetic properties of lithium disilicates, offering an improved alternative for endocrown restorations [43]. Jalalian et al. in their in vitro study demonstrated that ZLS has better margin adaption and higher fracture resistance than LDS, but they also ZLS have increased amounts of irreparable fractures [42]. In contrary, El Ghoul’s et al. study demonstrated that LDS exhibits the highest fracture resistance under lateral loading compared to RNC and ZLS, related to its superior adhesive properties and crystalline structure [40]. In adhesive interfaces, lateral forces are more hazardous than axial ones, because stresses are concentrated in the cervical region rather than distributed along the long axis, increasing the risk of irreparable fractures [20,40]. However, the high elastic modulus of lithium disilicate (LDS, 95 GPa) exerts greater stress on weaker surfaces, increasing the risk of irreparable fractures, whereas more flexible materials like resin nano-ceramics (RNC, 20 GPa) and zirconia-reinforced lithium silicate (ZLS, 70 GPa) distribute stress more homogeneously [40]. Manziuc et al. reported that zirconia-reinforced lithium silicate (ZLS) exhibited superior mechanical properties compared to feldspathic ceramics, lithium disilicate ceramics, and resin nano-ceramics, but demonstrates inferior esthetics due to the presence of tetragonal zirconia particles [43].

Resin-based materials, including resin nanoceramics (RNC), polymer-infiltrated ceramic networks (PICN), and millable composite resins, are emerging as reliable alternatives for endocrown restorations [2,19,37]. PICN consists of a 25% by volume polymer network and a 75% by volume ceramic network that combines the long-term aesthetic stability of ceramics with the preferred elastic modulus of resin composites [2,55]. RNC are composed of a resin-based matrix with dispersed fillers (nanoceramic particles), with the exact composition varying according to the specific product [2]. The materials exhibit high fracture resistance and an elastic modulus similar to that of dentin (18.6 GPa), thereby preventing catastrophic fractures. They tend to deform more before failing by changing the stress distribution and the contact with the surface of the restorative assembly [2,26,39,41]. Dartora et al. showed that PICN offers comparable fatigue failure load to LD restorations over the same number of loading cycles [41]. Beji Vijayakumar et al. concluded that RNCs have increased resilience to fractures compared to ZLS, although ZLS outperforms PICN in fracture resistance [2]. Keskin et al. reported survival rates of 82.7% for RNC and 86.8% for ZLS over a 3-year evaluation period, with no statistically significant difference between the two materials [32]. Resin-based materials experience fewer catastrophic failures, especially under axial loading, since they have the ability to absorb and distribute stresses homogeneously. Furthermore, these materials can be easily repaired intraorally [2]. Although their lower modulus of elasticity may reduce stress within the dentin, it can increase stress at the adhesive interface, thereby raising the risk of debonding [2,19,26,41]. The success of restorations depends on both internal and marginal fit, which is influenced by the material used. Taha et al. found that while LDGC, RNC, and resin-modified ceramics showed acceptable margin gaps, only RNC achieved a clinically acceptable fit [44].

To support clinical decision-making in the restoration of endodontically treated posterior teeth, a decision tree was developed based on the findings of this scoping review (Figure 3). This visual guide summarizes key criteria for selecting endocrown restorations, including remaining tooth structure, pulp chamber depth, presence of ferrule, available interocclusal space, material choice (LDS, ZLS, RNC), and adhesive technique. The aim is to assist clinicians in making evidence-based, case-specific restorative decisions that enhance the predictability and long-term success of treatment outcomes.

4.1.6. CAD/CAM-Fabricated Endocrowns: Precision, Efficiency, and Material Compatibility

The continuous use of CAD/CAM technology in restorative dentistry for milling endocrown restorations enables chairside treatment in a single appointment [36,56]. One of the main advantages demonstrated is the superior fracture resistance of CAD/CAM all-ceramic endocrowns, which surpasses that of non-CAD/CAM all-ceramic restorations [4,11,36]. According to Kuang et al. CAD/CAM all-ceramic endocrowns had a 5-year survival rate of 93.0% [33]. Fages et el. in their seven-year clinical trial observed a 98,66% survival rate of chairside CAD/CAM feldspathic ceramic endocrowns [30]. Similarly, Otto and Morman’s 12-year clinical study on chairside CAD/CAM feldspathic ceramic endocrowns revealed high survival rates, with 90.5% for molars and 75% for premolar [34]. Even though CAD/CAM endocrowns have extremely high survival rates and seem a successful long-term alternative, careful case selection and proper bonding techniques are essential to minimize risks and ensure successful outcomes.

4.2. Survival and Success Rates: Long-Term Outcomes and Clinical Predictability of Endocrowns

In terms of survival and success rates, endocrowns and post-and-core crowns appear to offer comparable outcomes for restoring endodontically treated molars [1,3,6,12,16,26,31]. Studies have shown that endocrowns demonstrate similar or even greater survival rates under repeated and static loads, generally due to their distinctive design and adhesive bonding mechanism, which promote better stress distribution and load transmission [4,23,27]. For instance, Fathi et al. reported a 5-year survival rate of 91.4% for endocrowns and 98.3% for post-core crowns, with no significant clinical differences [31], while Al-Dabbagh et al. demonstrated a 5-year survival rates of 89.1% for endocrowns and 98.2% for conventional crowns in molars [6]. In a 4-year retrospective study by Ayata et al. endocrowns demonstrated complete survival during follow-up period[57]. Belleflamme et al. highlighted impressive survival rates of up to 99% for endocrowns in posterior teeth, with Qamar emphasizing that this is the only long-term study providing a 10-year survival rate over in such an extended period [24,29]. Govare et al. mentioned that endocrowns had only 6% of root fractures and 71% of failures were due to loss of retention, whereas the root fracture rate for post or no post crowns was at 29% [26]. The success rate of endocrowns varies across different studies but consistently remains high, making them an excellent conservative option for restoring endodontically treated teeth.

4.3. Limitations of This Scoping Review

While this scoping review provides a broad overview of the available literature on endocrown restorations in endodontically treated molars, it is important to acknowledge several limitations associated with its methodological framework. Firstly, unlike systematic reviews, scoping reviews typically do not include an assessment of the quality of the eligible studies or an evaluation of the risk of bias using critical appraisal tools. As a result, the reliability and internal validity of the included sources were not critically appraised, which limits the ability to draw definitive conclusions or make evidence-based clinical recommendations. Additionally, although efforts were made to comprehensively search two major databases (PubMed and Scopus) and screen reference lists, relevant grey literature and unpublished data may have been missed. The variability in study designs, outcome measures, and reporting standards posed a significant challenge for data synthesis and meaningful comparison. These limitations highlight the need for future systematic reviews and meta-analyses to provide more definitive guidance based on rigorous appraisal and quantitative synthesis.

5. Conclusions

This scoping review provides a comprehensive synthesis of the current literature on the use of endocrowns for restoring extensively damaged posterior endodontically treated teeth. Based on the available evidence, endocrowns are particularly indicated in cases of significant coronal tooth structure loss, limited interocclusal space, and root canals with complex or atypical morphology. Notably, the presence of enamel along the majority of the restoration margins is a critical factor for ensuring long-term clinical success.Additionally, endocrown restorations are time-efficient, involving fewer procedural steps, reduced chairside time, and overall lower treatment costs compared to conventional post-and-core restorations. Furthermore, the use of resin-based materials and lithium disilicate ceramics has emerged as the most preferable choice, owing to their advancements in fracture resistance and aesthetic properties.

Multiple parameters influence the clinical and laboratory performance of endocrown restorations in endodontically treated teeth (ETT). Among others, the amount of the remaining tooth structure, the presence or absence of a ferrule, and the tooth’s location within the dental arch are the most critical factors for choosing a specific type of restoration. . Despite growing clinical acceptance, there is a continued need for standardization in both preparation protocols and material classification. The current literature reveals significant heterogeneity, primarily due to inconsistent descriptions of tooth preparation techniques for endocrowns.. While short-term findings are encouraging and support endocrowns as a viable alternative to conventional post-and-core restorations, the lack of robust long-term evidence limits definitive conclusions regarding their superiority in molars. Further well-designed, randomized clinical trials are necessary to resolve these discrepancies and to establish standardized treatment protocols.