Endocrown Restorations Research Articles

An in vitro evaluation of tensile strength of molar endocrown milled from various computer aided design and manufacturing materials

New computer-aided design and computer-aided manufacturing (CAD-CAM) materials have been reported to have suitable mechanical and physical properties for endocrown restorations. However, there is a lack of literature on evaluating the retention of endocrown using these materials. This in vitro study aimed to compare the retention of endocrowns fabricated from 3 different CAD-CAM materials. Sixty human mandibular third molars were divided into 3 groups (n = 20) according to the material used: (e.max CAD, Ivoclar AG, Schaan, Liechtenstein), (HC, Shofu, Koyoto, Japan), and (Brilliant Crios, Coltene, Altstätten, Switzerland) (n = 20). Specimens were stored in distilled water at 37 °C for 1 week and subjected to 5000 thermal cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to measure the tensile force. All results were statistically analyzed using one-way ANOVA (α = 0.05), and different failure modes were demonstrated. The results revealed that e. max CAD showed the highest mean tensile force value (402.35 ± 15.812) N, and the lowest mean tensile force value was for Brilliant Coris (118.90 ± 12.430) N (P < .001). It is concluded that e.max CAD endocrowns showed the highest tensile force values after thermocycling in comparison to other materials with a significant difference, which may have a promising impact on the survival of endocrown restorations.

A 3-year clinical evaluation of endocrown restorations with two different materials using the computer-aided design/ computer-aided manufacture system

ObjectiveTo compare the clinical efficacy of resin nanoceramic and zirconia-reinforced lithium silicate ceramic endocrowns in the treatment of endodontically treated teeth by assessing the clinical performance of restorations fabricated using a chairside computer-aided design/computer-aided manufacturing (CAD/CAM) system. Materials and methodsNinety endocrown restorations were fabricated on endodontically treated teeth using a CAD/CAM system. Fifty-two restorations were fabricated using Lava Ultimate blocks (LU, 3 M Espe, Seefeld, Germany) and 38 restorations were fabricated using Celtra Duo blocks (CD, Dentsply Sirona, York, PA, USA). The performance of the endocrown restorations was evaluated over a 3-year period using the modified United States Public Health Service (USPHS) criteria by two calibrated evaluators. The data were analyzed using Chi-square (x2) and Fisher exact tests (p < 0.05). ResultsThe restoration survival rates in the two groups were 82.7 % (LU) and 86.8 % (CD) (p = 0.6). Twelve restorations failed (8 LU, 4 CD) due to debonding (n = 4, 2 LU, 2 CD), ceramic fracture (n = 2, 1 LU, 1 CD), tooth fracture (n = 5, 4 LU, 1 CD), and secondary caries (n = 1, 1 LU) during the follow-up period. There was no statistically significant difference between the two materials according to the modified USPHS criteria (p > 0.05). ConclusionResin nanoceramic and zirconia-reinforced lithium silicate ceramic endocrown restorations fabricated using a chairside CAD/CAM system demonstrated acceptable clinical performance in the treatment of endodontically treated teeth. Clinical SignificanceResin nanoceramic and zirconia-reinforced lithium silicate ceramics are potential alternative materials for the chairside fabrication of endodontically treated teeth.

Comparison of the mechanical properties of RMC endo-crown restorations

Comparison of the mechanical properties of RMC endo-crown restorations

A Case Report of Molar Endocrown Restoration by Using KDU Endocrown Bur Set

A Case Report of Molar Endocrown Restoration by Using KDU Endocrown Bur Set

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.

Comparative evaluation of incorporation of ferrule in premolars endocrown designs to check any alterations in their fracture resistance: A pilot study.

Endocrown preparation of endodontically treated teeth as final restoration has been extensively studied for different teeth. Bindl et al. questioned the application of endocrowns for premolars due to the pulp chamber space's smaller dimensions, which diminish bonding surface area. The addition of ferrule into the endocrown preparations of premolars has not been extensively studied. Comparative evaluation of incorporation of the ferrule in premolars endocrown designs to check any alterations in their fracture resistance. The sample consisted of 40 maxillary first premolars without cracks or caries, extracted for orthodontic or periodontal purposes. The teeth were individually mounted with cold-cure acrylic resin. Group A: Composite endocrown without ferrule and Group B: Composite endocrown with ferrule. An endocrown former was prepared with elastomeric polyvinyl siloxane material (GC Exaclear). Endocrowns were then prepared with dual-cure core build-up composite-Core-x flow (Dentsply Maillefer, Switzerland) using the endocrown former so that morphologically, they all were almost identical. Endocrowns are cemented by dual-cure resin cement following manufacturer instructions. The fracture resistance of endocrowns with and without ferrule was evaluated and compared. The data were tabulated in Microsoft Excel and analyzed with SPSS version 24 software. The variables were presented with mean, standard deviation, and independent t-test. The P ≤ 0.05 is considered statistically significant. Group B (with ferrule) showed higher fracture resistance (622.06 N) than Group A (537.59 N) (without ferrule). Independent t-test showed that the difference was statistically significant (P = 0.008). Comparing the failure load findings, it could be concluded that ferrule-containing endocrown needed greater loads than ordinary endocrown restorations for failure.

The effect of restorative material selection and cementation procedures on the durability of endocrowns in the anterior teeth: an in-vitro study

ObjectiveTo investigate the fracture resistance and failure modalities of anterior endocrown restorations fabricated employing diverse ceramic materials, and bonded using various cementation methodologies.Materials and methodsForty maxillary central incisors were divided into two main groups based on the ceramic materials used; GroupI (Zir): zirconia endocrwons (Zolid HT+, Ceramill, Amanngirrbach) and GroupII (E-Max): e-max endocrowns (IPS e.max CAD, Ivoclar Vivadent). Both groups were further split into two subgroups depending on the cementation protocols; subgroup IA “ZirMDP”: endocowns cemented with MDP primer + MDP resin cement, subgroup IB (ZirNon-MDP): cemented with MDP primer + non-MDP resin cement, subgroup IIA (E-maxMDP): cemented with MDP primer + MDP resin cement, subgroup IIB (E-maxNon-MDP): cemented with MDP primer + non-MDP resin cement. (n = 10/subgroup). Endocrowns were manufactured using CAD/ CAM. Teeth were subjected to 10,000 thermal cycles. The fracture test was performed at 45o with a palatal force direction until the fracture occurred. Test results were recorded in Newton. The failure mode was examined using a stereomicroscope. A One-way ANOVA test was utilized to compare different groups regarding fracture strength values. Tukey`s Post Hoc was utilized for multiple comparisons.ResultsThe comparative analysis of fracture strength across the diverse groups yielded non-significant differences, as indicated by a p-value exceeding 0.05. Nonetheless, an observable trend emerged regarding the mode of failure. Specifically, a statistically significant prevalence was noted in fractures localized within the endocrown/tooth complex below the cementoenamel junction (CEJ) across all groups, except for Group IIB, “E-max Non-MDP,” where fractures within the endocrown/tooth complex occurred above the CEJ.ConclusionsCombining an MDP-based primer with an MDP-based resin cement did not result in a significant effect on the anterior endocrown fracture strength.Clinical relevanceRegardless of the presence of the MDP monomer in its composition, adhesive resin cement achieved highly successful fracture strength when used with MDP-based ceramic primers. Additionally, ceramic materials exhibiting elastic moduli surpassing those of dentin are discouraged due to their propensity to induce catastrophic fractures within the tooth structure.

CAD/CAM Materials for Endocrown Restorations: Evaluation of Microhardness, Flexural Strength, and Surface Characterization

Abstract Endocrowns have emerged as a promising option for restoring endodontically treated teeth, offeringa restorable fracture scenario. However, regarding the choice of material and its fracture resistance, there are gaps in the literature regarding the best indication. The objective of this research was to evaluate and compare the effect of restorative materials for CAD-CAM in the manufacture of endocrown restorations, through an in Vitro study on hardness and fracture resistance. For the study, CAD-CAM blocks were transformed into discs 12 mm in diameter and 1.2 mm thick (specimens). Three restorative materials were evaluated and distributed into experimental groups (N=12 specimens): Leucita- Reinforced Ceramic/ IPS Empress CAD (MRleu), Lithium Disilicate/ IPS Emax CAD (MRdis) and Nanoceramic Resin /Lava Ultimate (MRres). These restorative materials were evaluated for morphology (N=1) by Scanning Electron Microscopy (SEM) and surface chemistry (N=1) by dispersive energy spectroscopy (EDS). The specimens were evaluated when the Vikers micro hardness (N=1) with a load of 1kg and 10 indentations, as well as the resistance to biaxial flexion (N=10) at a test speed of 0.5 mm/min. After the fracture occurred, the fragments were examined under a stereomicroscope. The results were tabulated and analyzed using the Minitab statistical program. The results showed that the MRdis material demonstrated superior results in relation to hardness (P=0.000) and biaxial bending resistance (P=0.000), followed by MRleu and finally the MRres. The presence of inorganic particles on an organic matrix and the presence of Zirconium (Zr) stands out in Lava Ultimate. It was concluded that restorative materials for CAD-CAM in the manufacture of Endocrowns restorations have a significant effect on hardness and mechanical strength. Keywords: Ceramics. CAD-CAM. Hardness. Flexural Strength. Resumo As endocrowns surgiram como uma alternativa favorável para a restauração de dentes tratados endodonticamente, e se apresentam em um cenário de fratura restaurável. No entanto, em relação ao material de escolha e sua resistência à fratura existem lacunas na literature sobre a melhor indicação. O objetivo dessa pesquisa foi avaliar e comparar o efeito de materiais restauradores para CAD-CAM na confecção de restaurações endocrowns, através de um estudo in vitro sobre dureza e resistência à fratura. Para realização do estudo, blocos para CAD-CAM foram transformados em discos com 12 mm de diâmetro e 1,2 mm de espessura (espécimes). Três materiais restauradores foram avaliados e distribuídos em grupos experimentais (N=12 espécimes): Cerâmica Reforçada por Leucita/ IPS Empress CAD (MRleu), Dissilicato de Lítio/ IPS Emax CAD (MRdis) e Resina Nanocerâmica /Lava Ultimate (MRres). Estes materiais restauradores foram avaliados quanto à morfologia (N=1) através de Microscopia Eletrônica de Varredura (MEV) e química superficial (N=1) pela Espectroscopia de energia dispersiva (EDS). Os espécimes foram avaliados quanto à microdureza Vikers (N=1) com uma carga de 1kg e 10 indentações, como também em relação a resistência à flexão biaxial (N=10) em uma velocidade de ensaio de 0,5 mm/min. Os fragmentos após a fratura foram observados em estereomicroscópio. Os dados obtidos foram tabulados e analisados no programa estatístico Minitab. Os resultados observados mostraram que o material MRdis obteve resultados superiores em relação a dureza (P=0,000) e a resistência à flexão biaxial (P=0,000), seguido pelo MRleu e por fim o MRres. Destaca-se na Lava Ultimate a presença de partículas inorgânicas sobre uma matriz orgânica, além da presença de Zircônio (Zr). Conclui-se que materiais restauradores para CAD-CAM na confecção de restaurações Endocrowns apresentam efeito significativo quanto a dureza e resistência mecânica. Palavras-chaves: Cerâmica. CAD-CAM. Dureza. Resistência à Flexão.

Comparison of clinical efficacy of CAD CAM Endocrowns made of feldspathic ceramic, zirconia lithium silicate, and lithium disilicate: A two-year mixed cohort study

ObjectiveEndocrowns can be fabricated from various materials as a treatment option for endodontically treated teeth. This mixed cohort study aimed to demonstrate the clinical efficacy of Endocrowns made of feldspathic, zirconia lithium silicate, and lithium disilicate ceramics using a chairside CAD/CAM system. MethodsThe present study compared the clinical outcomes of 141 Endocrown restorations in posterior teeth of 85 patients in a two-year follow-up. The efficacy of restorations was evaluated in three aspects: esthetics, biological response, and function, with the aid of the FDI guideline, and presented as descriptive analyses. Additionally, the data were analyzed using Chi-square and Spearman correlation tests. The significance level was set at p = 0.05. ResultsThe study findings revealed that the type of restorations (feldspathic ceramic, zirconia lithium silicate, and lithium disilicate) (p > 0.05) and underlying teeth (molars and premolars) (p > 0.05) play no part in restorations’ failure. Caries' recurrence is primarily responsible for the failure of the endocrowns. Secondary caries and radiolucency were observed in four teeth (2.83 %). The clinical efficacy of 126 restorations (89.36 %) fell into the category of “clinically excellent” and “clinically good.” Ten restorations (7.09 %) were classified as “clinically sufficient/satisfactory,” and only five restorations (3.54 %) needed replacement due to having “clinically unsatisfactory” and “clinically poor” quality. ConclusionsEndocrowns showed a high success rate and durability in the short term, therefore can be considered a safe choice for restoring endodontically treated teeth. It is worth noting that caries were the most common reason for the failure of the restorations. Clinical significanceEndocrowns made of different ceramics have been proven reliable restorations for endodontically treated molars and premolars.

Effect of inlay, onlay, and endocrown restorations on the mode of failure and fracture resistance of endodontically treated maxillary premolar teeth. An in vitro study

Effect of inlay, onlay, and endocrown restorations on the mode of failure and fracture resistance of endodontically treated maxillary premolar teeth. An in vitro study

Influence of Cervical Marginal Elevation with Composite Resin and Biodentine on Vertical Marginal Gap of CAD/CAM Endocrown Restorations : An in vitro study

Influence of Cervical Marginal Elevation with Composite Resin and Biodentine on Vertical Marginal Gap of CAD/CAM Endocrown Restorations : An in vitro study

Marginal and internal gaps evaluation of endocrown restoration fabricated of different CAD/CAM materials using CBCT: An In vitro study

Marginal and internal gaps evaluation of endocrown restoration fabricated of different CAD/CAM materials using CBCT: An In vitro study

The Influence of Ferrule Design and Pulpal Extensions on the Accuracy of Fit and the Fracture Resistance of Zirconia-Reinforced Lithium Silicate Endocrowns.

The study aimed to assess the marginal, axial, and internal adaptation, as well as the fracture resistance of zirconia-reinforced lithium silicate (ZLS) endocrowns with varying pulpal inlay extensions and marginal geometry. Sixty extracted maxillary first molar teeth were divided into six groups (n = 10) according to pulpal inlay extension and marginal configuration. The first three groups (J2, J3, and J4) utilized prepared teeth for endocrowns without ferrule design and 2 mm, 3 mm, and 4 mm pulpal extensions, respectively. The second three groups (F2, F3, and F4) utilized prepared teeth with 1 mm shoulder margins and 2 mm, 3 mm, and 4 mm pulpal extensions. The endocrowns were fabricated from ZLS blocks using CAD/CAM milling technology. After cementation, the specimens underwent thermal aging for 5000 cycles and were evaluated for marginal adaptation. Using a universal testing machine, the fracture resistance was tested under quasistatic loading (1 mm/min). Two-way ANOVA and the Tukey's post hoc test were employed for data analysis (p ≤ 0.05). The results of this study revealed that endocrowns without ferrule exhibited superior fracture strength than a 1 mm ferrule design p < 0.05, irrespective of the inlay depth. All designs with and without ferrule and all inlay depths showed clinically acceptable marginal and internal fit. The conventional endocrown design without ferrule and 2 mm inlay depth showed the lowest surface gap. The pulpal surface showed the highest discrepancy among all groups compared to the other surfaces. Endocrowns without ferrule are more conservative and have higher fracture strength than 1 mm ferrule designs; extending the inlay depth showed a significant increase in fracture resistance of the 1 mm ferrule design, but not for the conventional design without ferrule and 2 mm inlay depth. All groups exhibited a high auspicious fracture strength value for molar endocrown restorations.

Fracture resistance of CAD/CAM endocrowns made from different materials in maxillary premolar interproximal defects.

This in vitro study aims to compare the fracture resistance of three CAD/CAM materials used in endocrown restoration of interproximal defects in maxillary premolars. 45 maxillary premolars extracted as part of orthodontic treatment were included. Following standardized root canal treatment, all teeth were prepared into Mesial-Occlusal (MO) cavity types. The samples were then randomly divided into three groups: LD [repaired with lithium disilicate glass ceramics (IPS e.max CAD)], VE [treated with polymer-infiltrated ceramics (Vita Enamic)], and LU [repaired with resin-based nanoceramics (Lava Ultimate)]. Axial static loading was applied using a universal testing machine at 1mm/min until fracture, and fracture resistance and failure modes were recorded. Regarding Fracture Resistance Values (FRVs), the LD group exhibited significantly higher values than the other two groups, VE (P = 0.028) and LU (P = 0.005), which showed no significant difference (P = 0.778). On the other hand, regarding failure modes, the LD group had a higher prevalence of irreparable fractures compared to the other two groups, VE (P < 0.001) and LU (P < 0.001), which showed no significant difference. Although lithium disilicate glass ceramics exhibited higher FRVs, they had a lower repair probability. In contrast, polymer-infiltrated ceramics and resin-based nanoceramics contributed to tooth structure preservation. For maxillary premolars with interproximal defects following root canal treatment, resin ceramic composites are recommended for restoration to enhance abutment teeth protection.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns.

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.

Clinical performance of computer-aided design/computer-aided manufacture lithium disilicate ceramic endocrown restorations: A 2-year study.

Optimal restoration methods for endodontically treated teeth (ETTs) have always remained an ongoing discussion among physicians in this day and age. ETTs have a tendency to fracture when chewing, compared to initial teeth. From the perspective of biology, preserving and restoring tooth structure is critical to maintaining biomechanical, functional, and esthetic harmony. Dental bonding techniques have lessened the necessity for post-and-core restorations in ETTs with severe substance loss. A minimally invasive endodontic restoration technique called "endocrown" was initially introduced by Bindl and Mörmann in 1999. The aim of the study was to clinically evaluate all-ceramic mandibular molar endocrowns made using computer-aided design/computer-aided manufacturing (CAD/CAM) following 2 years of follow-up. This unblinded study contains 56 patients with 56 mandibular molars, which had severe substance loss. After teeth preparation, lithium disilicate ceramic endocrowns were manufactured with the CEREC CAD/CAM system, and cementation was performed using a composite luting agent. The endocrowns were assessed using the modified United States Public Health Service criteria at baseline, 6 months, 1 year, and 2 years following placement. Patient satisfaction was evaluated using a questionnaire. This study used descriptive statistics, including mean, standard deviation, and 95% confidence intervals. Data were processed using STATA version 14.0 (StataCorp LLC, USA). Two endocrowns (3.6%) failed throughout the period of observation. The high clinical rating criteria (96.4%, count of 54) and the increased satisfaction percentage (94.6%, count of 53) remained practically stable during the follow-up assessments at 6 months and after 1-2 years. Endocrown offers a less invasive treatment option that may be a better method for endodontically treated mandibular molars. With contemporary CAD/CAM technology and new materials, time in the chair and esthetics optimally improved, bringing satisfaction to the patient.

Fracture Toughness of Monolithic Zirconia and Lithium Disilicate CAD/CAM Endocrown

&#x0D; Introduction: Endocrown is an indirect restoration following the endodontic treatment made of ceramic material as a substitute for post core crown. The endocrown is cemented to the inner wall of the pulp chamber and to the cavity margins to increase the macromechanical retention. Material commonly used are monolithic zirconia and lithium disilicate; both can be obtained using the CAD/CAM technique. Good endocrown restoration must be able to handle the chewing workload especially on the posterior tooth. Objective: To determine the difference in fracture toughness of monolithic zirconia and lithium disilicate CAD/CAM endocrown. Methods: This study used 6 endocrown CAD/CAM samples, attached to typodont prototype in 3D resin printing model produced by the printing machine. Samples were divided into 2 groups. Group A were monolithic zirconia endocrowns and group B were lithium disilicate endocrowns. The fracture toughness was calculated using the Universal Testing Machine (UTM). Results: Fracture toughness of the monolithic zirconia endocrown were 2.747 N and lithium disilicate were 769 N. The unpaired t test showed that there was significant difference in fracture toughness between groups (p &lt; 0,05). Conclusion: Monolithic zirconia endocrown has a higher fracture toughness compared to the lithium disilicate endocrown, but lithium disilicate is more recommended as an endocrown restoration material because its fracture toughness is closer to masticatory load of posterior teeth.

The fracture strength and the failure mode of lithium disilicate or resin nano ceramics as a crown, overlay, or endocrown restoration on endodontically treated teeth.

Different materials and restorative concepts have been proposed over the years to restore endodontically treated teeth (ETT). Monolithic ceramic and composite restoration can be lute to the tooh, without the use of a post. However, little is known how the material stiffness and presence of a composite core will affect the survival and failure mode. The objective of this in-vitro study was to evaluate the fracture strength and failure mode of endodontically treated molars, restored with ceramic or hybrid composite monolithic restoration, in the presence of absence of a composite core. Sixty depulped molars were restored with a lithium-disilicate (e.max CAD) or hybrid composite (Cerasmart) restoration. Both materials were used in a monolithic approach, but with 3 different designs: (a) monolithic endocrown, (b) crown with a separate composite core, and (c) overlay without core buildup or pulpal extension. Ten sound teeth were used as control group. All groups were thermocycled (10,000 cycles), subsequently loaded in a chewing simulator (100,000 cycles) and finally loaded until fracture. Peak fracture loads and failure modes were registered. No significant differences were seen between the groups in terms of fracture load. Failure modes were statistically significantly different among groups with significant correlation between restoration type and material. (p < 0.001 and p = 0.033, respectively). No group presented significantly higher fracture resistance. Although ceramic crowns and overlays presented the highest repairability, all restored ETT were within the range of the intact tooth' fracture strength. No restoration presented significant different fracture loads. However, the type of restoration and material choice were correlated to the fracture mode.

Overview on Restoration with Endocrown

Endocrown restorations are single prostheses that are made of reinforced ceramics and may be acid etched; they are recommended for endodontically treated molar teeth that have suffered a considerable loss of coronal structure. In order to provide a strong foundation for the restoration and strengthen the restored tooth structurally, the quality and integrity of the residual tooth structure should be carefully preserved. For this reason, Endocrown is used as a minimally invasive technique. Endocrowns are particularly recommended for molars with short, destroyed, dilacerated, or unstable roots. They may also be utilized when it is unable to achieve an acceptable thickness of the ceramic coating on the metal or ceramic substructures due to significant coronal dental tissue loss and constrained interocclusal space. Endocrowns provide a more beneficial choice than conventional and post- and core-retained restorations because of the little and simple preparation required. This favorable outcome can be attributable to a number of variables, including the preparation method, occlusal thickness, and elastic moduli. When it comes to material selection it is impossible to create what is called the material of choice since new material is constantly being introduced.

Effect of Thermomechanical Fatigue Loading on the Internal and Marginal Adaptation of Endocrowns Utilizing Different CAD/CAM Restorative Materials

To assess the impact of fatigue loading on the internal and marginal fit of CAD/CAM-fabricated endocrowns for restoring endodontically treated molars using different machinable blocks. A total of 72 mandibular first molars were prepared using a standardized method and were divided into four groups (n = 18), each restored with a different CAD/CAM material: group V = polymer-infiltrated ceramic (Vita Enamic); group K = partially stabilized tetragonal zirconia (Katana); group E = lithium disilicate ceramic (IPS e.max CAD; and group B = polyetheretherketone (BioHPP). Endocrowns were subjected to thermomechanical fatigue loading. Internal and marginal adaptation of the endocrowns were examined at 66 points using the sectioning technique and a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey post hoc test (α = .05). Statistical tests showed that adhesive cementation resulted in significantly increased marginal and internal gap values in all regions in all four tested groups (P < .001). After thermomechanical fatigue loading, all regions in groups B and K showed a statistically significant difference, while no significant differences were found in the regions in group V (P > .05). In group E, the marginal (F = 71.00) and pulpal (F = 28.065) regions showed statistically significant differences (P < .001). Polymer-infiltrated ceramics showed the lowest gap even after thermomechanical fatigue loading and may therefore provide enhanced clinical survival of the restored tooth, favoring the use of this material for fabricating endocrown restorations.