Endocrown: An Alternative Approach for Restoring Endodontically Treated Molars with Large Coronal Destruction

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

OBJECTIVE

To investigate the fracture resistance and failure modalities of anterior endocrown restorations fabricated employing diverse ceramic materials, and bonded using various cementation methodologies.

MATERIALS AND METHODS

Forty 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.

RESULTS

The 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.

CONCLUSIONS

Combining an MDP-based primer with an MDP-based resin cement did not result in a significant effect on the anterior endocrown fracture strength.

CLINICAL RELEVANCE

Regardless 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.

Clinical performance and wear resistance of milled resin composite material versus direct nanohybrid bulk-fill resin composite in the restoration of endodontically treated posterior teeth over 1 year: Randomized clinical trial

Context

The restorative complexities associated with endodontically treated teeth surpass those encountered with vital ones. The field of adhesive dentistry experienced a significant advancement that led to a shift in treatment approach toward bonded restorations.

Aim

The aim of the study was to assess the clinical performance of using indirect Milled composite or direct bulk-fill resin composite restorations for endo-treated teeth, as well as to measure the amount of wear on the occlusal tables of both restorations using a digital scanner.

Subjects and Methods

Participants were divided into two groups, where R1 represents the endodontically treated teeth restored with Milled composite, R2 represents the endodontically treated teeth restored with direct bulk-fill composite where 13 patients in each group were treated with a total number of 26 restorations in all patients. Where each restoration was assessed immediately at baseline (T0), 6 months (T6), and 12 months (T12) using the modified United States Public Health Service criteria. Moreover, wear was measured immediately at (T0) and (T12) intraorally and extraorally using intraoral scanners and three-dimensional surface-based superimposition software.

Statistical Analysis Used

Chi-squared test, Mann-Whitney U-test, Friedman's test, Nemenyi post hoc test, Shapiro-Wilk test, paired t-tests, intraclass correlation coefficient.

Results

At all intervals, the majority of the cases in both groups had an alpha score. Some cases exhibited bravo scores in both groups at T6 and T12 regarding the color match, marginal adaptation, marginal discoloration, and marginal integrity without statistically significant difference (P > 0.05). Direct nanohybrid bulk-fill resin composite showed a greater amount of wear without a statistically significant difference (P > 0.05). Extraoral measurement was significantly higher than intraoral measurement (P < 0.001). There was no significant reliability/agreement between both methods.

Conclusions

Both milled composite and direct bulk-fill resin composite restorations in endodontically treated teeth demonstrated appropriate clinical performance and minimal wear over an 1-year follow-up period.

Effect of ceramic materials and tooth preparation design on computer-aided design and computer-aided manufacturing endocrown adaptation and retentive strength: An in vitro study

OBJECTIVES

To evaluate how various tooth preparation designs impact the adaptation-both at the margins and internally-and the retentive strength of computer-aided design and computer-aided manufacturing (CAD/CAM) produced endocrowns.

MATERIALS AND METHODS

60 extracted human mandibular first molars were endodontically treated and assigned into three groups (n = 20) according to the tooth preparation design: Group N: butt joint design, Group F and F1 received 1- and 2-mm circumferential ferrule preparation, respectively. Endocrowns were milled using either lithium disilicate glass-ceramic (IPS emax ceramic) or monolithic zirconia. The internal and marginal adaptation of the endocrowns were evaluated using the replica technique. After cementation, the endocrowns of all test groups were dislodged axially at 0.5 mm/min using a universal testing machine. A 2-way ANOVA and the independent samples t-test (α = .05) were performed to statistically analyze the data.

RESULTS

The effect of changing the design of the tooth preparation (butt joint, ferrule) on the marginal and internal gap was shown to be statistically significant (p < .05); the lower gap values were recorded at the axial followed by cervical, marginal, and pulpal floor walls in both ceramic groups regardless of the teeth preparation design. The ANOVA test revealed similar average removal forces and stresses for the two types of tested ceramic materials.

CONCLUSION

IPS emax ceramic adapted better than monolithic zirconia ceramic, regardless of the preparation design. Ferrule preparation design is more retentive than butt joint preparation, regardless of the type of ceramic material used.

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

Context

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.

Aims

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.

Subjects and Methods

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.

Statistical Analysis Used

This study used descriptive statistics, including mean, standard deviation, and 95% confidence intervals. Data were processed using STATA version 14.0 (StataCorp LLC, USA).

Results

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.

Conclusions

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.

Knowledge and Awareness of Dental Practitioners About the Utilization of Endocrown in Post-endodontic Management

BACKGROUND

The objective of this study was to evaluate the knowledge, and awareness of dentists in Ha'il, Kingdom of Saudi Arabia, regarding the use of endocrown as post-endodontic restorations, utilizing an online questionnaire.

METHODS

A cross-sectional study was carried out among dental practitioners working in Ha'il, Kingdom of Saudi Arabia. Dentists who practice in the Ha'il were included in the current study. The survey study involved a sample size of 245 participants. The researchers employed the snowball sampling technique in this investigation. The validated, closed-ended questionnaires were disseminated to the entire sample of selected dental practitioners using electronic mail. The initial section of the survey encompassed inquiries pertaining to the demographic characteristics of the participants, encompassing variables such as gender, years of professional experience, and workplace. The subsequent section of the survey focused on assessing the participants' knowledge and opinions regarding the endocrown technique. The Chi-square test was employed to assess the associations between categorical variables.

RESULTS

The most of participants 228 (93.1%) had knowledge about endocrown and 94 (38.4%) of them received information from their educational institutions. Among the responses of the participants, 232 (94.7%) expressed their preference for utilizing endocrown restorations specifically for molar teeth. Moreover, 183 (74.7%) of respondents indicated that the endocrown is preferred when there is a restricted amount of inter-arch space available. A majority of respondents 152 (62.0%) indicated that the ferrule does not exert any influence on the endocrown. A majority of participants 135 (55.1%) expressed a preference for utilizing lithium disilicate ceramic in the fabrication of endocrown. The most of participants 209 (85.3%) opted to use resin cement for the purpose of cementation. The characteristics of gender, experience, and working place were found to have a significant relationship with the knowledge of the participants about endocrown (p <0.05).

CONCLUSIONS

The study participants need to enhance their knowledge and awareness pertaining to the utilization of endocrowns as a post-endodontic treatment.

In-Vitro Investigation of Marginal Adaptation and Fracture Resistance of Resin Matrix Ceramic Endo-Crown Restorations

The aim of this study was to evaluate the fracture resistance and marginal adaptation of endo-crown restorations produced from different resin-matrix ceramics (RMS) and the effects of these materials on marginal adaptation and fracture resistance. Three frasaco models were used by preparing (first) premolar teeth in three different margin preparations: butt-joint, heavy chamfer and shoulder. Each group was further divided into four subgroups according to the type of restorative material used: Ambarino High Class (AHC), Voco Grandio (VG), Brilliant Crios (BC) and Shofu (S) (n = 30). Master models were obtained using an extraoral scanner and fabricated with a milling machine. Marginal gap evaluation was performed with a silicon replica technique using a stereomicroscope. Replicas of the models (n = 120) were produced with epoxy resin. The fracture resistance of the restorations was recorded using a universal testing machine. The data were statistically analyzed using two-way ANOVA, and a t-test was applied for each group. Tukey's post-hoc test was performed to compare significant differences (p ≤ 0.05). The highest marginal gap was observed in VG, and the best marginal adaptation and the highest fracture resistance were found in BC. The lowest fracture resistance in Butt-joint preparation design was found in S. In addition, the lowest fracture resistance value in the heavy chamfer preparation design was found in AHC. The heavy shoulder preparation design displayed the highest fracture resistance values for all materials.

A composite resin core with a new zirconia tube reduces the surface strain at the cervical area of a mandibular molar: A model tooth study

PURPOSE

This study aimed to evaluate the surface strain at the cervical area of endodontically treated molars with a large pulp chamber restored using a composite resin core with three different types of core build-up systems.

METHODS

Reproduction models of human mandibular molars with prepared post spaces were used in this study. Roots duplicated with a composite resin were used as the experimental teeth. Three types of core build-up systems were used: composite resin core(RC), composite resin core with fiber posts (FC), and composite resin core with a prefabricated zirconia tube (ZC). Each group comprised eight specimens. Crowns made of yttria partially stabilized zirconia were cemented with dual-cure resin cement. Four strain gauges were attached to the surfaces of each specimen: the cervical area of the root and crown, on the buccal and lingual sides. The surface strain at each cervical area was measured using a static loading test and statistically analyzed.

RESULTS

In the case of static loading to the buccal cusp inner slope, ZC showed a significantly lower strain than RC in the crown on the buccal side and in the root and FC in the root. In the central fossa, ZC showed a significantly lower strain than FC in the root on the lingual side.

CONCLUSIONS

The prefabricated zirconia tube reduced the surface strain at the cervical area of the buccal/lingual root in molars; however, the effect was small in the cervical area of the crown.

Monolithic Endocrown Vs. Hybrid Intraradicular Post/Core/Crown Restorations for Endodontically Treated Teeth; Cross-sectional Study

The gold standard for restoring Endodontically Treated Teeth (ETT) with successful clinical longevity requires having minimal invasive preparations and maximal tissue conservation. Many dentists still consider hybrid post/core/crown to be the first choice for restoring ETT. Endocrown is a viable alternative treatment modality to hybrid post/core/crown. This study aims to assess the proper judgment of dentists working in Riyadh, Saudi Arabia on the use of monolithic endocrown versus hybrid post/core/crown for restoring ETT. The IRB of Princess Nourah Bint Abdulrahman University (PNU) Institutional Review Board reviewed this study. The questionnaire was validated and electronically distributed. The participants were pre-informed that their responses are completely anonymous and used for professional purposes only. The questionnaire surveyed dentists working in Riyadh, Saudi Arabia, about their preference for different ETT restorative modalities at various clinical scenarios. Data were analyzed using One-way ANOVA and t-test. All P-values of < 0.05 were considered statistically significant. A total of 275 responses were collected; 61.45% were females and 38.55% males. 56% of them were general practitioners, while 16% were consultants. Prefabricated post/core was the most preferred technique among the participants (18.55%), followed by endocrown (12.36%), and lastly, cast post/core (8.73%). The amount of remaining tooth structure was the most influential in the treatment selection (30.18%), followed by the presence or absence of 1–2 mm ferrule (17.82%). Interocclusal space (12.36%) was the least influential factor. Endocrown recorded 63.27% as the most preferred line of treatment in case of insufficient inter-occlusal space. 40.36% preferred endocrown for patients with occlusal risk factors. The amount of the remaining tooth structure and the tooth position significantly affect the treatment options of the participants. Endocrown was the most preferred treatment modality for restoring ETT for patients with occlusal consideration.

Comparative evaluation of marginal and internal fit of endocrowns using lithium disilicate and polyetheretherketone computer-aided design - computer-aided manufacturing (CAD-CAM) materials: An in vitro study

Purpose:

To evaluate the marginal and internal fit of endocrowns with different computer-aided design/computer-aided manufacturing (CAD-CAM) materials by measuring them with a stereomicroscope (μm).

Materials and Methods:

A mandibular first molar typodont tooth was prepared to receive an endocrown. The preparation was scanned using an extra-oral scanner. Endocrowns (n = 20) were fabricated using lithium disilicate (IPS e. max CAD LT block; CEREC Ivoclar Vivadent, Liechtenstein) and polyetheretherketone (PEEK) (breCAM. BioHPP^®; Bredent, UK) using CAD-CAM technique. Marginal gap was evaluated using a stereomicroscope at the midpoint of all four surfaces (mid buccal, mid lingual, mid mesial, mid distal). This was followed by sectioning of the endocrowns in a sagittal plane along with the prepared tooth to evaluate the internal fit at four different points (A, B, C, D) using a stereomicroscope. Statistical analysis was performed using one-way analysis of variance test.

Results:

Mean values of marginal gap of lithium disilicate and PEEK endocrowns are 56.6 ± 6.1 μm and 81.3 ± 10.1 μm, respectively. Mean value internal gaps of lithium disilicate and PEEK endocrowns are 158.2 ± 11.1 μm and 199.1 ± 13 μm, respectively. Results in the present study have shown that the marginal and internal fits of lithium disilicate endocrowns are superior to that of PEEK endocrowns.

Conclusions:

Based on the outcomes of this in vitro study, the marginal and internal fit of lithium disilicate endocrowns is better than PEEK endocrowns. The marginal gap clinically acceptable is <120 μm. The marginal gap values recorded in this study are within the acceptable range for both materials.

Influence of inner crown thickness on the bonding strength of porcelain fused to Co-Cr alloy endocrown

PURPOSE

The purpose of this study was to investigate the influence of inner crown thickness on the bonding strength of porcelain fused to Co-Cr alloy endocrown by shear strength test.

METHODS

According to the molar average anatomical data to obtain a simplified model for endocrowns, porcelain fused to Co-Cr alloy endocrowns were fabricated with four inner crown thicknesses: 0.3 mm, 0.5 mm, 0.8 mm, and 1.0 mm group, eight specimens were fabricated for each thickness group. Shear bond strength test was used to observe the metal-porcelain bonding strength, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis were performed after the test to evaluate the interface of metal-porcelain.

RESULTS

The shear bond strength means (in MPa) were: 10.50 ± 2.55 (0.3 mm), 13.21 ± 2.27 (0.5 mm), 14.47 ± 1.46 (0.8 mm), and 15.78 ± 2.81 (1.0 mm), one-way ANOVA showed that there was a statistically significant difference among the thicknesses (P < 0.05). The SEM observation showed tight bonding, and the EDS analysis showed element diffusion phenomenon at the metal-porcelain interface.

CONCLUSION

The bonding strength of porcelain fused to Co-Cr alloy endocrown varied according to the different thickness of inner crown and the thinner inner crown was recommended for tooth defects with limited prosthodontic space.

Survival Rate of CAD-CAM Endocrowns Performed by Undergraduate Students

OBJECTIVES

This study aimed to evaluate the success of computer-aided design-computer-aided manufacturing (CAD-CAM) endocrown restorations of endodontically treated teeth (ETT) performed by supervised undergraduate students. The study also intended to identify possible factors that may lead to failures.

METHODS AND MATERIALS

This observational open cohort study was based on clinical data from endocrown restorations performed by residents and undergraduate students in their 4th, 5th, and 6th year from July 2011 to May 2018. The presence of a tooth with an endocrown on the arch was the main criteria used to calculate the survival rate of restored teeth. The quality of the remaining endocrowns was evaluated referring to the FDI criteria. The cases of failure were categorized into either favorable or unfavorable.

RESULTS

A total of 343 ETT were restored with endocrowns in 315 patients. Among them, 199 patients encompassing 225 endocrowns were followed during a 56 ± 26 month period. The survival rate of restored teeth was found to be 81.8%, the estimated Kaplan-Meier survival rate being 71.8% at 9 years. Among the 41 failed cases, 32 were favorable (debonding and/or ceramic fractures) and 9 were unfavorable.

CONCLUSION

Endocrown restorations of posterior ETT using CAD-CAM technologies could be carried out by undergraduates with a low risk of failure. Teacher supervision could be reinforced, covering all steps of each endocrown procedure in order to avoid failures due to insufficient thickness or loss of retention.

Fracture resistance of resin based and lithium disilicate endocrowns. Which is better? - A systematic review of in-vitro studies

Objectives: The primary objective of this systematic review is to compare the fracture resistance of lithium disilicate (LDS)-based endocrowns and resin-based (RB) endocrowns of in-vitro studies, and the secondary objective is to compare their catastrophic failures.

Materials and Methods: The review protocol was registered in the P ROSP ERO database (CRD42020166201). A comprehensive literature search was done in PubMed, Cochrane, EBSCOhost and Google Scholar using key terms. Only in-vitro studies that compared fracture resistance of LDS-based endocrowns and indirect RB endocrowns in molars were included. Data extraction, risk of bias assessment and qualitative analysis of the included studies were performed.

Results: Five studies were included in this systematic review. The overall risk of bias for the included studies was moderate. Under axial loading, RB endocrowns showed similar fracture resistance when compared with LDS endocrowns. However, they showed better fracture resistance when compared with zirconia reinforced lithium silicate (ZLS) endocrowns. Furthermore, RB endocrowns showed fewer catastrophic failures than LDS-based endocrowns.

Conclusions: RB endocrowns have similar or better fracture resistance and fewer catastrophic failures when compared to LDS-based endocrowns.

Lithium Disilicate Ceramic Endocrown Biomechanical Response According to Different Pulp Chamber Extension Angles and Filling Materials

The purpose of this study is to evaluate the effect of pulp chamber extension angles and filling material mechanical properties on the biomechanical response of a ceramic endocrown. A 3D model of maxillary molar that underwent endodontically treatment was exported to computer aided design software to conduct finite element analysis (FEA). The endocrown model was modified considering different pulp chamber extension angles (right angle; 6°, 12° and 18° of axial divergence). The solids were imported into the computer aided engineering software in Standard for the Exchange of Product Data (STEP) format. Nine different filling materials were simulated to seal the orifice of the root canal system under each endocrown restoration (resin composite, bulk-fill resin composite, alkasite, flowable resin composite, glass ionomer cement, autocured resin-reinforced glass ionomer cement, resin cement, bulk-fill flowable resin composite, zinc oxide cement), totaling 36 models. An axial load (300 N) was applied at the occlusal surface. Results were determined by colorimetric graphs of von-Misses stress (VMS) and Maximum Principal Stress (MPS) on tooth, cement layer, and endocrown restorations. VMS distribution showed a similar pattern between the models, with more stress at the load region for the right-angled endocrowns. The MPS showed that the endocrown intaglio surface and cement layer showed different mechanical responses with different filing materials and pulp chamber angles. The stress peaks plotted in the dispersion plot showed that the filling material stiffness is proportional to the stress magnitude in the endocrown, cement layer and tooth adhesive surface. In addition, the higher the pulp chamber preparation angle, the higher the stress peak in the restoration and tooth, and the lower the stress in the cement layer. Therefore, 6° and 12° pulp chamber angles showed more promising balance between the stresses of the adhesive interface structures. Under the conditions of this study, rigid filling materials were avoided to seal the orifice of root canal system when an endocrown restoration was planned as rehabilitation. In addition, the pulp chamber axial walls were prepared between 6° and 12° of divergence to balance the stress magnitude in the adhesive interface for this treatment modality.

Effect of Restorative Material on Mechanical Response of Provisional Endocrowns: A 3D-FEA Study

The goal of this study was to evaluate the stress distribution in an endocrown restoration according to different provisional restorative materials. An endodontically treated maxillary molar model was selected for conducting the finite element analysis (FEA), with a determined amount of dental remnant of 1.5 mm. The model was imported to the analysis software (ANSYS 19.2, ANSYS Inc., Houston, TX, USA) in STEP format. All contacts were considered perfectly bonded. The mechanical properties of each structure were considered isotropic, linear, elastic, and homogeneous. Three different provisional restorative materials were simulated (acrylic resin, bis-acrylic resin, and resin composite). An axial load (300 N) was applied at the occlusal surface in the center of the restoration. Results were determined by colorimetric stress maps of maximum principal stress, maximum shear stress, and total deformation. The different materials influenced the stress distribution for all structures; the higher the material’s elastic modulus, the lower the stress magnitude on the cement layer. In the present study, all provisional restorative materials showed similar stress patterns in the endocrown and on the cement layer however, with different magnitude. Based on this study limitation, the use of resin composite to manufacture provisional endocrowns is suggested as a promising material to reduce the stresses in the cement layer and in the dental tissue surfaces.

A Combination of Full Pulpotomy and Chairside CAD/CAM Endocrown to Treat Teeth with Deep Carious Lesions and Pulpitis in a Single Session: A Preliminary Study

A higher chance of carrying out a successful full pulpotomy may depend on whether the coronal restoration can be completed within a single appointment. The development of chairside CAD/CAM (Computer Aided Design and Manufacturing) technology has made it possible to carry out indirect restoration of endodontically treated teeth in a single session. This study aimed to evaluate the long-term outcome of a full pulpotomy with Biodentine™ immediately covered with a chairside CAD/CAM endocrown on teeth affected by pulpitis and deep carious lesions. The investigation involved a cohort of 30 molars that were treated by pulpotomy and CAD/CAM endocrown. Clinical and radiological examinations were scheduled at 1, 6, and 12 months postoperatively. Overall, all treatments were effective at any time during the follow-up. The results of this study need to be confirmed with a longer-term follow-up to allow for comparison with the literature. This original combination of endodontic and restorative treatments provides an Endo-prosthetic continuum in a single session, with the objective of long-term success in terms of tooth health.