Access Cavity Research Articles

Effect access cavity preparation and taper instrumentation on upper premolar fracture

Background : Fractures are the most undesirable thing in endodontically treated teeth. The main reason in endodontically treated teeth has a considerable risk for fractures is the loss of tooth structure. Objective : This study aims to determine the effect of access cavity preparation and instrument taper percentage on upper premolar fractures. Material and Methods : Twenty-four upper premolar samples were stored in sterile saline solution. The sample was divided into 2 large groups which were then divided into two groups for each group by random allocation. Twelve contracted endodontic cavity (CEC) preparations and the remaining twelve samples using traditional endodontic cavity (TEC) techniques. Each group was prepared with 6 samples 4% taper instrumentation and 6 samples 8% taper instrumentation. Each sample was irrigated with 5 ml of NaOCl. After that, the sample is tested using a universal testing machine. Result : The CEC group showed a significant reduction in fracture rates compared to the TEC group (p <0.05), but there was no significant difference in the fracture in the tapering instrumentation (p> 0.05). Conclusion : Preparation with the concept of minimally invasive CEC provides better resistance to fractures in the upper premolar while tapering instrumentation does not affect the fracture of the upper premolars.

How loss of tooth structure impacts the biomechanical behavior of a single-rooted maxillary premolar: FEA

To evaluate the influence of the loss of coronal and radicular tooth structure on the biomechanical behavior and fatigue life of an endodontically treated maxillary premolar with confluent root canals using finite element analysis (FEA). An extracted maxillary second premolar was scanned to produce intact (IT) 3D model. Models were designed with an occlusal conservative access cavity (CAC) with different coronal defects; mesial defect (MO CAC), occlusal, mesial and distal defect (MOD CAC), and 2 different root canal preparations (30/.04, and 40/.04) producing 6 experimental models. FEA was used to study each model. A simulation of cycling loading of 50N was applied occlusally to stimulate the normal masticatory force. Number of cycles till failure (NCF) was used to compare strength of different models and stress distribution patterns via von Mises (vM) and maximum principal stress (MPS). The IT model survived 1.5 × 1010 cycles before failure, the CAC-30.04 had the longest survival of 1.59 × 109, while the MOD CAC-40.04 had the shortest survival of 8.35 × 107 cycles till failure. vM stress analysis showed that stress magnitudes were impacted by the progressive loss of coronal tooth structure rather than the radicular structure. MPS analysis showed that significant loss of coronal tooth structure translates into more tensile stresses. Given the limited size of maxillary premolars, marginal ridges have a critical role in the biomechanical behavior of the tooth. Access cavity preparation has a much bigger impact than radicular preparation on their strength and life span.

The Effect of Traditional and Ultraconservative Access Cavities On the Increase in Surface Area of Root Canal After Instrumentation: An in Vitro Study

Introduction: In this study, we aimed to evaluate the impact of ultraconservative and traditional endodontic access cavities on the total percentage increase in the surface area of root canals. Methods: Endodontic instrumentation was performed on 30 simulated maxillary first premolars with two roots using traditional and ultraconservative access cavities via ProTaper Next rotary files. The pre- and postinstrumentation photographs of the root canals were analyzed blindly using Fiji software to determine the percentage increase in surface area. Results: A significant increase in the surface area of the root canal was observed with an ultraconservative endodontic access cavity compared to a traditional access cavity. The difference between the palatal and buccal roots was not significant, but there was a significant difference among the coronal, middle, and apical thirds of the root canal. Conclusion: Ultraconservative access cavities have a significant impact on the increase in surface area of the root canal after instrumentation.

A Comparative Evaluation of Efficacy of Various Obturating Techniques for the Presence of Voids.

Evaluation of the efficacy of different obturating techniques and assessment of the presence of voids in different regions of the canal. Sixty permanent single-rooted teeth with complete, mature root apices without any anatomic variation having straight patent root canals were included in the present study. Access cavity preparation followed by biomechanical preparation was done. Samples were divided into three groups-Group A: Single cone obturation, Group B: GuttaFlow 2, and Group C: GuttaCore, and obturation was carried out. The samples after obturation were stored at 370°C and 100% humidity in an incubator for 7 days to give adequate time for obturating materials to set. Cone beam computed tomography was performed with i-cat Cb 500 machine. The voids were checked on the root canal wall. The statistical analysis was done and the data after the statistical analysis was presented. GuttaCore obturators presented a lesser volume of voids followed by GuttaFlow 2 than the single cone techniques. All the obturation techniques presented an inadequacy of obturation when the pre- and post-obturated volume of the root canal space was calculated. However, no statistically significant obturated volume differences were found between single cone and GuttaFlow 2 or between GuttaFlow 2 and GuttaCore system.

A Retrospective Study on the Fracture Toughness of the Coronal Restorations in Endodontically Restored Teeth. An Original Research.

The best treatment for the deeply carious tooth that cannot be restored is by the root canal therapy. This method has saved many patients from the loss of tooth. The common practice is either to deliver a full crown or close the access cavity with restoration. Hence in this study, the clinical longevity of the routine practice is tested for by analyzing the fracture toughness and the survival of the teeth that were restored endodontically with various materials. The hospital records were retrospectively evaluated from 2000 to 2010 for a decade. The demographics as well as the survival and the failure rates noted and compared for the various types of the restorations. The number of the walls of the teeth was also compared. Thousand teeth were considered in the study. Less than 7% of teeth had coronal fractures. Of the 93% teeth that had survived, the most common restoration was Individual post (+ crown) followed by GIC, amalgams, and crowns. The mean survival of the crown+ bridge & gold restoration was highest. The mean survival was 10 ± 2 years for the restored teeth without any fractures at the coronal level. The failure was greatest for the GIC followed by amalgam, and the variations when compared with other restorations were significant. There was no significant difference for the number of the walls on the crown; however, the number of walls present was proportional to the survival rate. The teeth that were covered with a crown were comparatively fracture resistant and had a better survival rate compared to other restorations. GIC showed highest fracture, and the post core with crown had the best survival. Restoration of the lost crown architecture and the reinforcement are the best methods that can be followed for the survivals.

Biomechanical Properties of Maxillary Second Molar with Different Endodontic Cavity Designs - A Finite Element Analysis.

To evaluate the biomechanical properties of maxillary second molars with three different cavity designs - Traditional, Conservative, and Extended - endodontic cavities using the finite element analysis method. Three finite element models of a maxillary second molar with three different types of endodontic cavities were designed and restored. Each model was subjected to three different force loads directed at the occlusal surface. The stress distribution patterns and the maximum von Mises (VM) stresses were calculated and compared. Vertical force of multipoint load on the occlusal surface and lateral forces to the palatal cusp showed the maximum stress values in the extensive cavity design, followed by the traditional cavity design and then the conservative cavity design. The VM stress distribution in the conservative endodontic cavity was minimal when compared to other access cavity designs.

Access Cavity Preparation and Localization of Root Canals Using Guides in 3D-Printed Teeth with Calcified Root Canals: An In Vitro CBCT Study.

Pulp canal obliteration (PCO) is a significant complication in endodontics that can occur due to various factors. Cone beam computed tomography (CBCT) is a useful diagnostic tool for identifying root canal anatomy and variations, and guided endodontics is emerging as an alternative treatment solution for teeth with partially or entirely obliterated pulpal canals. However, the accuracy of CBCT-guided 3D-printed guides on different materials and layer thicknesses is not well understood. Therefore, this study aimed to evaluate the accuracy of guides prepared using CBCT images on 3D-printed teeth with stereolithography (SLA) using three different materials and two different layer thicknesses. This study found that 3D-printed guides were accurate and reliable for accessing 3D-manufactured obliterated teeth and reaching the apical area. No significant differences in distance or angle measurements were found when different guide materials were used, suggesting that materials can be selected based on availability and cost. These findings contribute to the knowledge base regarding the effectiveness of 3D printing technology in guided endodontics and can help to identify the most suitable materials and techniques for this application.

The effects of laser and ultrasonic irrigation activation methods on smear and debris removal in traditional and conservative endodontic access cavities.

In this study, it was aimed to evaluate the smear and debris removal efficiency of laser and ultrasonic irrigation activation methods in traditional and conservative endodontic access cavity preparations. 60 freshly extracted human mandibular molar teeth were randomly divided into 2 groups according to the access cavity preparation (n = 30): Traditional endodontic access cavities (TEC) and Conservative endodontic access cavity (CEC). After the access cavity preparation, the mesiobuccal root canals were prepared to 35/0.4 with the VDW Rotate file system. Teeth with completed root canal preparation were randomly divided into 3 subgroups according to the final irrigation activation protocol (n = 30): Conventional needle irrigation, passive ultrasonic activation and laser activation. The crowns of the teeth were removed and the mesiobuccal roots were divided longitudinally into two halves, mesial and distal. Samples were scanned with scanning electron microscopy. Photomicrographs in the coronal, middle, and apical thirds of each specimen were taken at a magnification of 200 for debris and 1000 for evaluation of the smear layer. Data were analysed using the three-way Robust Anova test and Bonferroni test.The effect of access cavity design on remaining smear (p = 0.057) and debris (p = 0.5) was not statistically significant. The effect of the interaction of access cavity and irrigation activation on the remaining smear and debris was not statistically significant (p = 0.556, p = 0.333). Significantly fewer smears were detected in the laser activation group than in the ultrasonic activation and control groups. Conservative access cavities did not differ from conventional access cavities in terms of debris and smear.

Effect of cleaning materials on microtensile bond strength of resin composite to primary dentin contaminated with root canal sealers

BackgroundThere have been no studies on the bond strength of adhesives with dentin surfaces contaminated with root canal sealers in primary teeth without underlying permanent teeth germs. This study investigated the cleaning materials used for primary tooth dentin contaminated with root canal sealers. The aim was to increase the success rate of root canal treatment in pedodontics clinics and retain the teeth for longer.MethodsThe occlusal enamel layer was removed, followed by the application of root canal sealers (AH Plus or MTA Fillapex) to the dentin and cleaning using different irrigation solutions (saline, NaOCl, and ethanol). The specimens were restored using a self-etch adhesive and composite. Sticks with a thickness of approximately 1 mm were obtained from each sample, and the bond strengths were measured using a microtensile testing device. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.ResultsThe control and AH Plus saline groups had the highest bond strengths. The groups cleaned using ethanol had the lowest bond strengths (p < 0.01).ConclusionCleaning the dentin with saline-soaked cotton pellets provided the best bond strengths. Therefore, saline is the most effective material for removing both epoxy resin- and calcium silicate-based root canal sealers from the access cavity.

Minimally invasive access cavities in endodontics

Background: The access cavity is a critical stage in root canal therapy and it may influence the subsequent steps of the treatment. The new minimally invasive endodontic access cavity preparation concept aims to preserve sound tooth structure by conserving as much intact dentine as possible including the pulp chamber's roof, to keep the teeth from fracturing during and after endodontic treatment. While there is great interest in such access opening designs in numerous publications, still there is a lack of scientific evidence to support the application of such modern access cavity designs in clinical practice. This review aims to critically examine the literature on minimal access cavity preparations, explain the effect of minimally invasive access cavity designs on various aspects of root canal treatment, and identify areas where additional research is required. Data: An electronic search for English-language articles was performed using the following databases: Google Scholar, PubMed, and Research Gate. The following keywords were used: "minimally invasive access cavity", "conservative endodontic cavity ", and "classification of access cavity". Study selection: 64 papers that were the most relevant to the topics in this review were selected between 1969 to 26 February 2022. Conclusions: Minimally invasive access cavities can be classified into conservative, ultraconservative, truss access, caries and restorative-driven cavities. There is a deficiency of proof that a minimally invasive access cavity maintains the resistance to fracture of endodontically treated teeth greater than traditional access cavities. There was no difference in the percentage of untouched walls and debris removal in teeth with conservative vs traditional access cavities, however, truss and ultraconservative access cavities resulted in poor irrigation efficacy compared to traditional ones. Also, the lower cyclic fatigue resistance of rotary instruments and root canal obturation with voids were associated with minimally invasive access cavities. The studies about minimally invasive access cavities still have a wide range of methodological disadvantages or register unsatisfactory or inconclusive results. Therefore, further research on this topic is needed especially with the everyday advancement of techniques and armamentarium used in endodontics.

Student\'s confidence level in performing root canal treatment and its correlation with encountered errors

This study aims to investigate the confidence level of undergraduate final-year dental students in performing root canal treatment (RCT) and the relationship to the problems encountered during RCT. A validated online questionnaire was distributed to final-year dental students at Universiti Teknologi MARA. The questionnaire utilized both scaled responses and closed-ended questions to gain data regarding students’ confidence levels in performing root canal treatment. : In this study, 93.4% of the students were confident in placing a rubber dam, 90.8% were confident in injecting local anesthesia and root canal irrigation. Procedures that were rated as least confident were access cavities and management of interappointment flare-ups. For the mean rate of self-confidence in performing RCT in the dentition, maxillary anterior teeth (4.24±0.63) ranked highest followed by mandibular premolars (4.11±0.72), whereas the least confidence was in treating maxillary molars (3.38±0.69). Higher scores of self-confidence were in the management of necrotic pulp (4.22±0.65), followed by vital pulp treatments (3.95±0.61). The main mishaps that students encountered were canal blockage (57.9%) and underestimation of length (52.6%). There is no statistically significant correlation between the confidence level and encountered errors. . : The mean overall confidence score of different endodontic procedures was high, which is 80%. Examining the confidence level of students is a crucial part of this study, which can help to enhance the quality of endodontic education in areas that need improvement.

Evaluation of the anxiety among the undergraduates during endodontic treatment

To evaluate the anxiety level among the undergraduate dental students during and after endodontic treatment. In this study questionnaire was prepared with 15 questions based on stress level, anxiety, and work load among dental undergraduates during endodontic treatment. The questionnaire were circulated and filled by participants in a self-report method.: 70% of students reported that canal location is the reason for the fear of endodontic treatment, but their anxiety starts before the treatment begins. Around 60% of students have moderate level of anxiety before starting the treatment and 70% manifest sweating during the endodontic treatment. Access cavity preparation of the posterior teeth and oral fluid control were considered as the factors to feel stressed during the procedure among 51% and 29% of the undergraduates respectively.: According to this study, higher level of anxiety were seen among the undergraduates and therefore, the stress control must be focused before starting the procedure, access cavity preparation and while handling endodontic instruments.

A Novel Self-Assessment Method for Training Access Cavity on 3D Printed Endodontic Models.

New technologies can facilitate the transition from pre-clinical to clinical settings. We investigate students' satisfaction with a novel learning method adopted in access cavity exercises. Students performed their access cavity on inexpensive, in-house 3D printed teeth. Their performances were evaluated by scanning the prepared teeth with an intraoral scanner and visualized using a mesh processing software. Then, the same software was used to align the tooth prepared by the student and the teacher's one for self-assessment purposes. Students were asked to answer a questionnaire about their experiences with this new learning method. From the teacher's perspective, this novel learning approach was easy, straightforward and affordable. Overall, student feedback was positive: 73% found that access cavity assessment by scanning was more useful compared to a visual inspection under magnification and 57% reported that they had a better understanding of errors and mishaps. On the other hand, students pointed out that the material used to print teeth was too soft. The use of in-house 3D printed teeth in pre-clinical training is a simple way to overcome some of the drawbacks associated with extracted teeth, such as limited availability, variability, cross-infection control, and ethical constraints. The use of intraoral scanners and mesh processing software could improve student self-assessment.

Ex-vivo and in-vivo validation of a novel measuring protocol for guided endodontics

ObjectivesTo (1) validate the use of a post-operative intraoral scan (IOS) versus Cone Beam Computed Tomography (CBCT), gold standard, on its ability to measure the accuracy of guided endodontics, and (2) present clinical data on the accuracy of guided endodontics. MethodsFour models, including 10 extracted teeth each, were created. Forty guided access cavities were planned on dentin to simulate pulp canal obliteration (PCO). Two operators performed guided access cavities. A post-operative CBCT and IOS were acquired. The coronal, apical, and angular deviations were measured with CBCT and IOS. Clinical accuracy was measured using an IOS acquired immediately after drilling the access cavity with the aid of a guide. Data analysis was performed using multiway Anova and corrected for simultaneous hypothesis testing according to Tukey. P ≤ 0.05 was considered statistically significant. Descriptive statistics on the clinical accuracy of guided endodontics were performed. ResultsThirty-eight cavities were assessed with a mean length of 13.8 mm. No statistical difference between operators and methods was found for all parameters (P > 0.05). Thirty-three patients were treated with guided endodontics and measured using an IOS. Results show an average coronal, apical, and angular deviation of 0.2 mm, 0.45 mm, and 1.91° respectively. The average length of the access cavities was 12.5 mm. ConclusionsAn IOS can be used to measure the accuracy of guided endodontics. Clinical data showed high accuracy of guided endodontics with a mean apical deviation smaller than 0.5 mm and a mean angular deviation of less than 2°. Clinical significanceThe use of an IOS does not involve additional radiation exposure. A safety margin of at least 1 mm around the planned trajectory should be respected when planning the case to minimize the possibility of root perforation.

Pulpal anesthesia of maxillary first molars using 4% articaine infiltration in patients with symptomatic irreversible pulpitis: a randomized controlled clinical trial.

This study aimed to compare the anesthetic efficacy of 1.8mL (one cartridge) and 3.6mL (two cartridges) buccal infiltration and buccal plus palatal infiltration of 4% articaine in maxillary first molar teeth with symptomatic irreversible pulpitis. This randomized single-blind clinical trial was conducted on 45 patients with symptomatic irreversible pulpitis of maxillary first molars (Trial Registration No: IRCT2015011020238N2_2015). The patients were randomly divided into three groups (n = 15) for buccal infiltration of 1.8mL articaine plus 1:100,000 epinephrine (group 1), buccal infiltration of 3.6mL articaine (group 2), and buccal infiltration of 1.8mL articaine plus palatal infiltration of 0.5mL articaine (group 3). The pain intensity was measured by the Heft-Parker visual analog scale (VAS) during injection and during access cavity preparation. No pain or mild pain during treatment was considered as successful anesthesia. Data were analyzed by the Tukey's post hoc test. The three groups had a significant difference in frequency of the perceived pain during injection (P = 0.01). A higher volume of 4% articaine and injection of articaine in both buccal and palatal sides provided a significantly higher anesthesia success rate (P = 0.049 and P < 0.01, respectively). The highest success rate was recorded in group 3 (93.33%) followed by group 2 (80%) and then group 1 (53.33%). Increasing the administered volume of 4% articaine with 1:100,000 epinephrine and addition of palatal infiltration to buccal infiltration of articaine can significantly increase the success of anesthesia in maxillary first molars with symptomatic irreversible pulpitis. Achieving deep anesthesia in teeth with irreversible pulpitis is a critical parameter in management of patients who are in urgent need of root canal treatments.

Analysis of Temperatures Generated during Conventional Laser Irradiation of Root Canals-A Finite Element Study.

The success of endodontic treatment is dependent on the removal of bacteria. A modern strategy to reduce bacterial load is laser irradiation. During this procedure, there is a local increase in temperature with possible side effects. The aim of this study was to determine the thermal behavior of a maxillary first molar when performing the conventional irradiation technique using a diode laser. For this study, a 3D virtual model of a maxillary first molar was created. The preparation of the access cavity, the rotary instrumentation of the palatal root canal and the laser irradiation protocol were simulated. The model was exported in a finite element analysis program where the temperature and heat flux were studied. Temperature and heat flux maps were obtained, and the temperature increase on the internal wall of the root canal was analyzed. The maximum temperature value exceeded 400 °C and was maintained for less than 0.5 s. The obtained temperature maps support the bactericidal effect of diode laser and the limitation of damage to surrounding tissues. On internal root walls, the temperature reached several hundred degrees Celsius, but for very short durations. Conventional laser irradiation is an adjuvant method of decontamination of the endodontic system.

In Vitro Evaluation of the Accuracy of Three Electronic Apex Locators Using Different Sodium Hypochlorite Concentrations.

Background and Objectives: The aim of this study was to compare the accuracy of three types of electronic apex locators (EALs) when two different concentrations of NaOCl irrigation solutions are used by two operators. Materials and Methods: After creating the access cavities for 20 single rooted extracted teeth, the actual canal length (ACL) of each canal was determined visually using a #10 file and magnification. The teeth were subsequently inserted in plastic molds filled with alginate. The electronic measurement of root canal length (EWL) was performed using three different electronic apex locators: Root ZX II, Apex ID, and Dual Pex. Two independent operators, an endodontic specialist with 20 years practice and an undergraduate student in the final year of study, performed the irrigation procedures with two different concentrations of NaOCl (2% and 5.25%), and then measured the EWL using each of the EALs. The accuracy of all EALs, was determined in each case by subtracting the EWL from the ACL. Statistical analyses were performed using one-way ANOVA test. Results: In the presence of 2% NaOCl solution, for a margin error of ±0.5 mm, Root ZX II, Apex ID, and Dual Pex presented an accuracy of 90%, 80%, and 85% respectively. The increase in the concentration of the irrigation solution affected the accuracy of Root ZX II and Apex ID for both operators, diminishing it to 75% for the same margin error, but improved Dual Pex's accuracy to 100%. Conclusions: The best accuracy in working length determination was obtained by Root ZX II for 2% NaOCl solution and by Dual Pex for 5.25% NaOCl solution with no significant statistical difference when compared.

Microleakage Evaluation of Temporary Restorations Used in Endodontic Treatment-An Ex Vivo Study.

(1) Background: Coronal microleakage can lead to endodontic treatment failure. This study aimed to compare the sealing ability of different temporary restorative materials used during endodontic treatment. (2) Methods: Eighty sheep incisors were collected, uniformized in length, and access cavities were performed, except for in the negative control group, where the teeth were left intact. The teeth were divided into six different groups. In the positive control group, the access cavity was made and left empty. In the experimental groups, access cavities were restored with three different temporary materials (IRM®, Ketac™ Silver, and Cavit™) and with a definitive restorative material (Filtek Supreme™). The teeth were submitted to thermocycling, and two and four weeks later, they were infiltrated with 99mTcNaO4, and nuclear medicine imaging was performed. (3) Results: Filtek Supreme™ obtained the lowest infiltration values. Regarding the temporary materials, at two weeks, Ketac™ Silver presented the lowest infiltration, followed by IRM®, whereas Cavit™ presented the highest infiltration. At four weeks, Ketac™ Silver remained with the lowest values, whereas Cavit™ decreased the infiltration, comparable to IRM®. (4) Conclusion: Regarding temporary materials, Ketac™ Silver had the lowest infiltration at 2 and 4 weeks, whereas the highest infiltration was found in the Cavit™ group at two weeks and in the IRM® group at 4 weeks.

Effect of Traditional and Conservative Endodontic Access Cavities on Instrumentation Efficacy of Two Different Ni–Ti Systems: A Micro-CT Study

This study aims to compare the shaping efficiency of the nickel–titanium instrument systems, One Reci and ProTaper Ultimate, using micro-CT (micro-computed tomography) in traditional and conservative endodontic access cavities. The experimental groups were formed according to the type of access cavity and Ni–Ti file system to be used. Sixty mandibular molar teeth were randomly divided into two main groups, the conservative access cavity (CAC) group and the traditional access cavity (TAC) group, and randomly divided into two subgroups according to the file system. The groups were compared with a two-way ANOVA analysis in terms of volume change, surface area, non-instrumented area transportation, and thickness of the dentin in the danger zone area after root canal preparation. The groups showed no statistically significant differences in terms of volume change, surface area, or the thickness of the dentin in the danger zone area after root canal preparation (p &gt; 0.05). However, in the percentage of non-instrumented areas post-instrumentation between groups, the percentage of non-instrumented areas was statistically higher in specimens with CAC compared to TAC (p &lt; 0.05). Canal transportation was higher in CAC at all distances from the apical region (p &lt; 0.05). Within the limitations of this study, CAC can also be used with some precautions as an alternative to TAC.

Endocrown Feasibility for Primary Molars: A Finite Element Study.

To study the possibility of using pediatric endocrowns to restore the second primary molar using three-dimensional (3D) finite element analysis. A 3D finite element model was built for a pediatric mandibular molar, starting with laser scanning a naturally extracted tooth. The access cavity had an elliptic shape with 6 mm width, 4 mm height, and 2 mm depth with a wall taper angle of 5 degrees.Two materials (Zr and E-max) were tested for the endocrown and two cementing materials (glass ionomer and resin cement) with 20 to 40 μm thickness. Twelve case studies were reported within this research as the applied load of 330 N was tested with three angulations vertical, oblique at 45 degrees, and laterally. Twelve linear static stress analyses were performed. The resultant stresses and deformations' distribution patterns did not alter much, and values were within the threshold of physiological tolerance. Deformations were negligibly changed with changing endocrown and cement materials. In contrast, endocrown stresses indicated zirconia endocrown would have a long lifetime, while E-max one will have a relatively short lifetime. Analysis results indicated that bone was negligibly affected by changing endocrowns and cementing materials. Both tested endocrown materials can be used safely. Zirconia endocrowns may have a much longer lifetime than E-max.