Knowledge and Practice of Endocrown Restorations Among Dental Students and Dentists in Sirte, Libya

Background Restoring endodontically treated teeth has long posed a challenge for clinicians. The endocrown (EC) is an innovative and conservative restoration designed for teeth with severely damaged coronal structures. ECs offer performance that is equivalent to or even exceeds that of traditional post-core-crown treatments. Purpose This web-based cross-sectional survey aimed to evaluate the level of knowledge and practical experience regarding ECs as post-endodontic prostheses among dental students and practitioners in Libya. Methods A 22-item structured questionnaire was created using Google Forms and distributed to final-year students, interns, faculty at the College of Dentistry at Sirte University, and practicing dentists in Libya. The sample comprised 290 participants. The questionnaire was divided into three sections: the first assessed demographic variables such as gender, education level, country of graduation, and workplace; the second evaluated knowledge of ECs through 11 questions; and the third focused on EC practice, also comprising 11 questions. Statistical analysis was conducted using IBM SPSS Statistics for Windows, Version 21.0 (Released 2012; IBM Corp., Armonk, NY, USA). Results A total of 50.7% of participants indicated that EC restorations are suitable for molar teeth, 41.4% noted that a butt joint finish line is used for EC preparation, and 66.9% preferred all-ceramic materials for ECs. Nearly 72.8% reported that computer-aided design/computer-aided manufacturing technology is employed for EC fabrication. Additionally, 61.7% agreed that EC designs offer higher fracture resistance compared to conventional crowns. Despite this, 64.5% of participants had not cemented an EC in their clinic in recent years. Significant differences in knowledge and practice regarding ECs were observed across various factors, including gender, education level, country of graduation, and workplace. Conclusion Most participants demonstrated an acceptable level of knowledge and practical experience with EC restorations. Therefore, incorporating ECs as a major topic in the postgraduate prosthodontics curriculum is recommended.


Introduction
Restoring endodontically treated teeth has long posed challenges for clinicians.These teeth undergo physiological changes in dentin microstructure and composition, making them susceptible to increased brittleness, reduced retention and stability, compromised substrate adhesion, and, ultimately, prosthesis failure [1].The endocrown (EC) is a modern, conservative solution designed to address extensively damaged coronal structures in endodontically treated teeth [2].Introduced by Bindl and Mörmann [3], ECs are indirect ceramic monoblock restorations that gain retention from the pulp chamber.These restorations adhere to the pulp chamber using the micromechanical retention features of its borders [4].ECs are particularly effective for cases involving significant tooth structure loss in posterior areas [2].They demonstrate superior performance in molars or teeth with larger pulp chambers [5][6][7] compared to maxillary [8][9][10] or mandibular premolars [11][12][13].ECs often provide equivalent or even superior outcomes compared to traditional postcore-crown treatments, which involve intra-radicular posts (metal or fiber), cores (composite, amalgam, or glass ionomer), and crowns (ceramic or porcelain fused to metal) [14].Metal posts, with a higher modulus of elasticity than dentin, can increase the risk of root fractures and failures [15].In contrast, fiber posts, with mechanical properties similar to dentin, offer a more uniform stress distribution [16].Compared to traditional posts, cores, and crowns, ECs require less clinical time, simpler preparation, fewer appointments, and offer excellent esthetic results [17].They are also an ideal option when posts are contraindicated due to short or narrow canals [18].
Several guidelines have been established for the proper preparation of teeth to receive an EC.An occlusal reduction of 2-3 mm is required.It is recommended to use a 90-degree butt-joint margin with a width of 1-1.2 mm [2].Whenever possible, cervical margins should be placed supragingivally and smoothly transitioned internally to the flat pulpal floor.Additionally, an occlusal divergence of 5-7 degrees is necessary for the endodontic access hole and coronal pulp cavity, ensuring continuous preparation.The depth of the pulp chamber should be adequate to provide retention and resistance [9,19,20].EC restorations can be fabricated using either computer-aided design/computer-aided manufacturing (CAD/CAM) systems or conventional heat-pressing ceramics.Currently, CAD/CAM technology is preferred for its ability to deliver high-quality restorations with reduced chairside time [18].
Dental students and dentists must be well informed about various treatment options to meet patient expectations and ensure the long-term success of prosthetic restorations.To date, no research has specifically evaluated the knowledge and practice of EC restorations in Libya.Therefore, this web-based cross-sectional survey was conducted to assess the current state of knowledge and practice regarding ECs as a post-endodontic prosthesis among Libyan dental students and dentists.

Materials And Methods
The study was approved by the Biomedical Research Ethical Committee of the National Center for Disease Control (NCDC), Ministry of Health, Libya, and conducted in accordance with the principles of the Helsinki Declaration [21].
A structured questionnaire was developed using Google Forms and was accessible via PCs, mobiles, or tablets.It was distributed from December 2023 to January 2024 to assess participants' knowledge and practice regarding EC restorations.The questionnaire was sent to all final-year students, interns, and faculty at the College of Dentistry, Sirte University, as well as to dentists across Libya.All participants provided informed consent.
The 22-item closed questionnaire was based on the 2023 study by Al Moaleem et al., with minor modifications [22].Respondents selected one answer per question using checkboxes, and each participant was allowed to respond only once.All questions were mandatory, and Google Forms recorded the responses.
The questionnaire consisted of three sections (Appendix 1).The first section collected demographic information, including gender, level of education, country of graduation, and workplace.The second section assessed knowledge of ECs with 11 questions, while the third section focused on EC practice with another 11 questions.

Study design
This cross-sectional study aimed to establish a baseline level of awareness and management of endodontically treated teeth restored with ECs among oral health practitioners in Sirte, Libya.

Ethical consideration
The study adhered to the guidelines set forth by the World Medical Association Declaration of Helsinki.Ethical approval was granted by the Biomedical Research Ethics Committee of the NCDC, Ministry of Health, Libya (approval number NBC: 002.H-23.22).Informed consent was obtained from all participants prior to the study.

Participants
A questionnaire survey was conducted among dental students, interns, faculty members, and practitioners in public hospitals and private clinics in Sirte, Libya.The sample size was calculated according to the formula used for the whole population: n = Z2 × p × q / e2, where n = the required sample size, q = 1 -p, with a 95% level of confidence and sample error ±5%.Assuming q = 0.5 to achieve the maximum sample size, a total of 290 participants were surveyed.
The questionnaire, designed to assess dentists' knowledge and practice of ECs, was distributed from December 2023 to April 2024.It included questions relevant to understanding EC restorations, ensuring the study's goals were met.The survey targeted undergraduate students, general dentists, specialists, and consultants working in both academic and clinical settings.
To assess the reliability of the questionnaire, the test-retest method was employed.Ten participants from the Faculty of Dentistry, Sirte University who were not involved in the main study completed the questionnaire twice within a two-week interval.Pearson's correlation coefficient (Pearson's r) indicated a significant stability coefficient, suggesting good test-retest reliability.Internal consistency was measured using Cronbach's alpha, with a value of α = 0.767, indicating adequate internal consistency between items [23].

Statistical analysis
Statistical analysis was conducted using IBM SPSS Statistics for Windows, Version 21.0 (IBM Corp., Armonk, NY, USA), and results were visually presented using GraphPad Prism version 8 (GraphPad Software, Inc., San Diego, CA, USA).Nominal and categorical variables were described using simple descriptive statistics, including counts and percentages.The significance level was set at 0.05.Comparisons of results between groups defined by participants' characteristics were performed using the chi-square test.

Variables
Frequency Percent   Regarding the practice of ECs in their clinics, 188 (64.5%) of participants reported not having cemented ECs in recent years.Only 125 (43.1%) consistently used rubber dams during EC cementation, while 150 (51.7%) always utilized X-rays to verify the extension of ECs in the pulp chamber.The predominant cause of failure, identified by 190 (65.5%), was the debonding of ECs.For tooth preparation, 177 (61%) found it no more difficult than conventional post, core, and crown preparations, and 165 (56.9%) felt that EC preparations and impression-making were not more time-consuming.Additionally, 187 (64.5%) believed that the presence of an enamel margin enhanced fracture resistance and bonding strength (Table 3).

Question
Frequency Percent Q12: How many ECs did you cement in the clinic in previous years?Using the chi-square test, no significant association was found between knowledge and gender (p > 0.05) (Table 4).However, significant differences in responses were observed based on education level for questions Q1, Q6, Q8, Q10, and Q11 (p < 0.05) (Table 5).Differences were also significant for the country of graduation concerning questions Q1, Q4, Q5, and Q8 (Table 6).Additionally, significant variations were noted in responses related to the workplace of participants for questions Q1, Q2, and Q3 (Table 7).There was no significant association between practice and gender or country of graduation (p > 0.05) (Table 8, Table 9).Significant differences were observed in practice related to the level of education for questions Q13 (p = 0.001), Q14 (p = 0.006), and Q15 (p = 0.021) (Table 10).Regarding the workplace, a significant difference was found for question Q16 (p = 0.019), while no significant differences were observed for other questions (p > 0.05) (Table 11).

Variables
Q16: Tooth preparation steps to receive EC are more difficult than post, core, and crown.Yes

Discussion
ECs are employed to restore extensively damaged, endodontically treated teeth.They depend on the remaining tooth structure for support, with retention provided by the pulp chamber and surrounding dentine [7].EC restorations present an effective and conservative approach for restoring severely destructed endodontically treated teeth.However, they require careful case selection, precise preparation, and accurate cementation techniques to ensure long-term success.This cross-sectional study aimed to assess the level of knowledge, awareness, and beliefs about ECs among dental students and practitioners in Sirte, Libya.It found that approximately half of the dentists obtained their information about ECs from college (51.7%), while 23.4% sourced their knowledge from the media.The remainder came from a combination of methods, including workshops and emails.
In our study, half of the participants believed that ECs are used exclusively for molars, while 26.9% reported using them for both premolars and molars.Sevimli et al. [17] suggested that ECs can effectively restore endodontically treated incisors, premolars, and molars.However, Bindl et al. [24] concluded that a small pulp chamber in premolars can negatively impact resin-cement adhesion.Additionally, Lander and Dietschi [25] found that the greater length compared to the width of most premolars increases the risk of fracture and displacement of ECs.Therefore, it is recommended to limit the use of ECs to molar teeth, particularly those with shorter crowns and narrow or calcified root canals [23,26].
Preparing teeth to receive ECs is a straightforward procedure that is not time-consuming.In our study, most participants (61%) reported that EC procedures are not difficult.Additionally, 56.9% found that tooth preparation and impression-making for ECs are less time-consuming compared to conventional post, core, and crown procedures.Deepak and Nivedhitha [27] conducted a cross-sectional study on dentists in Chennai, India, and concluded that ECs can serve as a practical alternative for restoring mutilated teeth.The preparation for ECs involves creating a 1.0-1.2mm circumferential butt margin with a central retention cavity inside the flat pulp chamber.This design does not rely on support from the root canals but is constructed as a single monoblock unit that integrates both the crown and core [3,28].A butt-joint margin, also known as a cervical sidewalk, is a 90-degree circumferential enamel margin with a width of 1-2 mm [19,29].In our survey, 41.4% of participants indicated that this is their preferred margin for EC preparation.
Compared to the shoulder margin with the ferrule effect, the butt-joint margin is simpler and provides better internal adaptation and marginal integrity [30].
The enamel margin improves bonding and enhances the strength of the restoration by providing a horizontal surface that can withstand compressive stresses [29,31].In our study, 66.9% of participants reported that the materials used for ECs are ceramics, specifically monolithic zirconia or lithium disilicate.Lithium disilicate is often preferred due to its adhesion properties, imparted by its silica content and its ability to be etched [32,33].Composite resin materials, on the other hand, are weaker, less durable, and prone to microleakage [34,35].Therefore, careful consideration of the preparatory design and material selection is essential during the preparation of ECs [5,36,37].Similar preferences for ceramic materials were observed by Wahab et al. [38] and Al Moaleem et al. [22], who noted the preference for ceramic materials among Jordanian and Saudi dentists, respectively.Zaki et al. [23] reported that 82.5% of participants believed ECs could be fabricated using pressable ceramic technology.However, our study found that 72.8% of participants preferred using CAD/CAM technology for EC fabrication.Regarding the fracture strength of EC restorations, Biacchi and Basting [39] demonstrated that ECs have significantly higher fracture strength compared to conventional crowns supported by glass fiber posts.In our study, 68.3% of participants agreed that ECs can serve as a substitute for post-and-core systems.Lin et al. [40] found that ECs transfer force to the pulp chamber's wall and periodontal tissue rather than to the root canal wall and geometrically reduce the rotation center of the restoration compared to post-core and full crown systems.Despite this, 42% of participants in our survey noted that ECs might sometimes increase the incidence of tooth fractures.Ghoul et al. [6] found that 90% of EC failures were due to tooth fractures and restoration dislodgement occurring on the side opposite the stress.
Al Moaleem et al. [22] found that only 6% of participants had cemented more than 10 ECs, with the majority (42.02%) reporting they had never used ECs based on their training experience.This aligns with our findings, as most participants (64.5%) had never cemented ECs in their clinics.This is likely due to the prevalence of prefabricated post-core procedures, followed by ECs and cast post-core.During the cementation of ECs, a rubber dam was employed to ensure proper isolation.The tooth surface was etched with 37% phosphoric acid for 15 seconds, then rinsed and dried.A bonding agent was subsequently applied and polymerized with a curing light for 20 seconds [26].In our study, 43.1% of participants used rubber dams during EC cementation.Postoperative radiographic evaluation is crucial for long-term success; in this study, about half of the participants (51.7%) performed post-cementation radiographs of ECs.
The difference in modulus of elasticity between dentine and ceramic can lead to debonding of the restoration and potential root fractures.Therefore, proper case selection is crucial for the long-term success of ECs [23].Most dental professionals (80.0%) identified debonding as the primary failure mode for ECs [41].This finding is consistent with our study, where 65.5% of participants also cited debonding as a major cause of EC failure.Based on the current study, dental practitioners generally demonstrate adequate theoretical knowledge and clinical performance regarding ECs.However, the varied responses suggest a need for a clear protocol outlining the indications, diagnosis, preparation, and cementation of ECs.This need is evident for both experienced and less experienced dentists, as regular application of these materials and procedures in practice is essential to align with the associated knowledge.
This study has several limitations, including a limited sample size from a single population and a short study duration.

Conclusions
ECs can effectively replace conventional post-core-crown systems for restoring endodontically treated teeth, particularly when dealing with severely damaged dental tissues.Our study found that most participants demonstrated a good level of knowledge and practical experience with EC restorations.Therefore, incorporating ECs as a major topic in the postgraduate prosthodontics curriculum is recommended.

Section 2 : 3 : 10 Q13:
et al.Cureus 16(8): e66211.DOI 10.7759/cureus.66211Knowledge about endocrown Q1: From where did you get the information about endocrown?goal of using endocrown is to achieve minimal invasive preparations and preserve the existing tooth structure.True False I don't know Q4: Which type of finish line is used during endocrown preparation?Shoulder Chamfer Buttjoint I don't know 2024 Abu Sittah et al.Cureus 16(8): e66211.DOI 10.7759/cureus.6621119 of 25Q5: The material of choice for endocrown is all ceramic.fracture resistance of endocrown is higher than that of conventional crowns.TrueFalse I don't know Q8: The ideal extension of endocrown in the pulp chamber is: the floor of the pulp chamber is irregular, the failure of endocrown is increased.2024 Abu Sittah et al.Cureus 16(8): e66211.DOI 10.7759/cureus.endocrownbe a substitute for a conventional post, core, and crown?Practice about endocrown Q12: How many endocrowns did you cement in the clinic in previous years?How often do you use a rubber dam during endocrown cementation?2024 Abu Sittah et al.Cureus 16(8): e66211.DOI 10.7759/cureus.66211Always Sometimes Never Q14: How often do you use a radiograph to check the endocrown extension in the pulp chamber?Always Sometimes Never Q15: The most common "failure mode" of endocrown is debonding.Yes No I don't know Q16: Tooth preparation steps to receive endocrown are more difficult than post, core and crown.Yes No I don't know Q17: Tooth preparation and impression to receive endocrown are more time-consuming than post, core, and crown.Yes No I don't know 2024 Abu Sittah et al.Cureus 16(8): e66211.DOI 10.7759/cureus.6621122 of 25

TABLE 1 : Distribution of subjects according to gender, level of education, country of graduation, and working place (demographic parameters)
Q10: Does EC increase the rate of tooth fracture?

TABLE 2 : Distribution of subjects based on their EC knowledge
CAD/CAM, computer-aided design/computer-aided manufacturing; EC, endocrown

TABLE 5 : Knowledge association with education level
The goal of using EC is to achieve minimal invasive preparations and preserve existing tooth structure.If the floor of the pulp chamber is irregular, the failure of EC is increased.
CAD/CAM, computer-aided design/computer-aided manufacturing; EC, endocrown Q7: The fracture resistance of EC is higher than that of conventional crowns.

TABLE 7 : Knowledge association with place of work
CAD/CAM, computer-aided design/computer-aided manufacturing; EC, endocrown

TABLE 8 : Practice association with gender
Q13: How often do you use a rubber dam during EC cementation?