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

OBJECTIVE

Endocrowns 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.

METHODS

The 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.

RESULTS

The 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.

CONCLUSIONS

Endocrowns 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 SIGNIFICANCE

Endocrowns made of different ceramics have been proven reliable restorations for endodontically treated molars and premolars.

Biomechanical behavior of all-ceramic endocrowns fabricated using CAD/CAM: A systematic review

PURPOSE

This study performed a systematic review to assess the biomechanical behavior of all-ceramic endowcrowns fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) for the restoration of endodontically treated teeth.

STUDY SELECTION

Three electronic databases (PubMed, Web of Science, and Scopus) were searched by operators specializing in health sciences databases searches to answer the following focused question based on the Population, Intervention, Comparison, Outcome (PICO) format: "Whether all-ceramic CAD/CAM endocrowns (Intervention) used to restore human endodontically treated teeth (Population) exhibit superior fracture resistance (Outcome) compared to non-CAD/CAM all-ceramic or non-ceramic endocrowns (Comparison)." The methodological quality assessment was performed using previously conducted systematic reviews of in vitro studies. The outcomes were expressed as the mean ± the standard deviation (SD).

RESULTS

Seventeen in vitro studies were included. The materials used in these studies were lithium disilicate glass-ceramic, polymer-infiltrated ceramic, zirconia-reinforced lithium silicate glass-ceramic, resin/hybrid nanoceramics, zirconia-reinforced lithium silicate ceramics, and feldspathic ceramic. The fracture resistance of endocrowns using different ceramics varied as follows: (i) IPS e.max CAD (2863.62 ± 51.47 N), (ii) Vita Enamic (1952 ± 378 N), (iii) Vita Suprinity (1859 ± 588 N), (iv) Cerasmart (1981 ± 169.5 N), (v) LAVA Ultimate (2484 ± 464 N), (vi) Celtra Duo (1618.30 ± 585.00 N), and (vii) Cerec Blocs (236.29 ± 32.12 N).

CONCLUSIONS

CAD/CAM all-ceramic endocrowns can withstand occlusal forces in the posterior region. All-ceramic endocrowns improve the fracture strength of endodontically treated teeth. Lithium disilicate crowns were commonly and successfully used in the included studies. More in vitro investigations that implement uniformity in material and measurement approaches are required to strengthen the evidence currently available in the literature regarding the durability of all-ceramic endocrowns.

Triple scan evaluation of internal and marginal adaptation of overlays using different restorative materials

OBJECTIVE

Problems in the confection of indirect restorations may increase the marginal and internal gap. This study aimed to quantify the marginal and the internal fit of overlays fabricated with three different materials.

MATERIALS AND METHODS

Standardized cavities were prepared on endodontically treated human third molars and digital impressions were done using an intraoral camera (Trios 3). Restorations were designed (n = 15) and fabricated with three materials: Hybrid ceramic (Cerasmart; GC Corp, EUROPE), high-strength lithium disilicate (GC Initial® LiSi Press; GC Corp, Tokyo, Japan), and zirconia reinforced Lithium Silicate Glass Ceramic (Vita Suprinity; Vita, Germany). Axial, marginal, pulpal, and gingival gaps were calculated by measuring the distance between the restoration and the tooth at several reference points. Two-Way analysis of variance was used for statistical analysis. The significance level was set at α = 0.05.

RESULTS

Mean gap was significantly influenced by the material (p < 0.001), gap localization (p < 0.001), and interaction between the factors (p = 0.002). For all materials, the highest gap was observed at gingival and pulpal surfaces (p ≤ 0.015). LiSi Press achieved the overall lowest values at axial values measurements (p ≤ 0.003).

CONCLUSIONS

The performance of a CAD/CAM system relative to marginal adaptation is influenced by the restorative material used. High-strength lithium disilicate seems to be showed the best marginal adaptation.

CLINICAL SIGNIFICANCE

Marginal and internal adaptation of CAD/CAM restorations could be influenced by the type of material chosen.

Restoration of Severely Damaged Endodontically Treated Premolars: Influence of the Ferrule Effect on Marginal Integrity and Fracture Load of Resin Nano-ceramic CAD-CAM Endocrowns

OBJECTIVES

To explore the ferrule effect on Resin Nano-Ceramic (RNC) premolar endocrown marginal integrity and fracture resistance.

METHODS

Thirty-six root-canal-treated premolars were cut 2 mm above the cemento-enamel junction (CEJ). They were restored with standardized RNC computer-aided design/computer-aided manufacturing (CAD/CAM) restorations (Lava Ultimate, 3M Oral Care, St. Paul, MN, USA) and divided into three groups (n=12): endocrowns with a 3-mm endo-core (Group 1), endocrowns with a 3-mm endo-core and a 2-mm ferrule (Group 2), and conventional post-and-core crowns with a 2-mm ferrule (Group 3). All specimens were submitted to thermo-mechanical cycling loading (TMCL) (1.7 Hz, 49 N, 600 000 cycles, 1500 thermocycles). Margins were analyzed before and after the TMCL. In the second part of the experiment, the surviving specimens were submitted to unidirectional monotonic loading until fracture. Fragments were then analyzed using scanning electron microscopy (SEM) and the fracture mode was established.

RESULTS

Endocrowns of Groups 1 and 2 performed better than conventional crowns (Group 3) in terms of marginal continuity. Differences in fracture load values within all groups were not statistically significant. Most of the specimens fractured in a non-repairable way.

CONCLUSIONS

The present test failed to provide evidence of any kind of difference between endocrowns with and without a ferrule in terms of load-bearing capacity and marginal integrity after fatigue. Further studies are needed to confirm the role of the ferrule in adhesive restorations of endodontically treated teeth.

Comparing endocrown restorations on permanent molars and premolars: a systematic review and meta-analysis

Objectives The objective of this systematic review was to evaluate the success of endocrown restorations on molars in comparison with endocrown restorations on premolars.Registration number The methodology for this review is registered with the PROSPERO database (CRD42019149543).Data sources Medline, Embase, Dentistry & Oral Sciences Source and Cochrane CENTRAL were searched through January 2020, supplemented with hand searching of additional relevant journals.Data selection and data extraction Two independent reviewers screened studies against predefined inclusion criteria and extracted data.Data analysis Narrative analysis was carried out and random-effects meta-analysis was performed where possible.Results Out of the selected eight studies, reported success rate of endocrown restoration in molars varied from 72.73% to 99.57% and in premolars ranged from 68.75% to 100%, with a follow-up range of 3-19 years. The pooled odds ratio and 95% confidence intervals for failure rates in molars compared to premolars in four studies selected for meta-analysis were 1.096 (95% CI: 0.280, 4.292).Conclusions These findings showed similar success rates and no difference in the rate of endocrown failures between molars and premolars, thus suggesting that premolars may be considered suitable candidates for endocrowns. However, the findings should be interpreted with caution due to methodological limitations of the included studies. Further better quality and specifically designed controlled trials directly comparing the clinical performance of endocrowns on molars and premolars are required.

Clinical efficacy of ceramic versus resin-based composite endocrowns in Chinese adults: study protocol for a randomized controlled trial

BACKGROUND

Endocrown restoration is widely used to restore endodontically treated teeth. However, the clinical effects of different computer-aided design/computer-aided manufacturing (CAD/CAM) materials for endocrown restoration are not clear. The primary objective of this trial is to compare the clinical efficacy of resin-based bloc and ceramic endocrowns for restoring endodontically treated teeth.

METHODS

The proposed resin-based bloc and ceramic endocrown assessment trial is a parallel group-designed randomized controlled trial. We will recruit 156 adults between 18 and 75 years old with a minimum of one such molar. The inclusion criteria were good oral hygiene habits, root apex of molar without evident damage, receipt of standard endodontic treatment, need for endocrown restoration, and only one endocrown restoration performed per patient. Patients participating in another study or those with systemic diseases, disabilities, or known allergies to used materials will be excluded. All patients will be randomized and restored with resin-based bloc and ceramic endocrown according to a random number table. Clinical evaluations will be performed at baseline and after treatment at 6, 12, and 24 months, in accordance with the modified Federation Dentaire Internationale (FDI) criteria, by two independent evaluators. The primary outcome is marginal adaptation; secondary outcomes include wear, tooth integrity, fracture of material and retention, marginal staining, and patient view. All data will be analyzed by an independent statistician. Signed rank-sum tests will be used for intragroup comparisons. Wilcoxon rank-sum tests will be used for intergroup comparisons. Hierarchical logistic regression will be used to adjust the baseline and other important indicators.

DISCUSSION

This study will investigate endocrowns of two CAD/CAM materials for endodontically treated molars. The results may help clinicians choose the better CAD/CAM material option and explain to patients the advantages and disadvantages of these two materials with evidence-based support. For patients, the results may lead to improvement in long-term restoration.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04033380. Registered on 24 July 2019.

Fracture Toughness Comparison of Three Indirect Composite Resins Using 4-Point Flexural Strength Method

Objectives  The advantages of indirect composite restorations such as less crack formation during their computer-aided design/computer-aided manufacturing process, compared with ceramic restorations, have resulted in their growing popularity. However, restoration failure is a major concern with regard to the long-term clinical success of restorations and may occur as the result of propagation of a crack originated from an internal flaw in the restoration. This study aimed to compare the fracture toughness of three indirect composite resins.

Materials and Methods In this in vitro experimental study, 10 specimens measuring 3 × 3 × 18 mm were fabricated of Gradia, Crios, and high impact polymer composite indirect composites. A single edge notch with a diameter < 0.3 mm and 0.3 mm length was created in the 9 mm longitudinal dimension of specimens using a no. 11 surgical scalpel. The specimens were then subjected to 4-point flexural strength test in a universal testing machine with a crosshead speed of 0.1 mm/s until failure.

Statistical Analysis  Data were analyzed using IBM SPSS Statistics via one-way analysis of variance (ANOVA) and Tukey’s HSD (honestly significant difference) test. The statistical power was set at p ˂ 0.05.

Results  One-way ANOVA showed a significant difference in fracture toughness of the three composite groups ( p = 0.000). According to the Tukey HSD analysis, the fracture toughness of HIPC was significantly higher than that of the other two composites. The fracture toughness of Gradia was significantly lower among all.

Conclusions  Within the limitations of this study, the results showed that high temperature-pressure polymerization can increase resistance to crack propagation and subsequently improve the clinical service of indirect composite restorations. Although we do not know the filler volume percentage of HIPC, it seems that filler volume percentage of the composite is inversely correlated with fracture toughness.

Marginal gap and fracture resistance of CAD/CAM ceramill COMP and cerasmart endocrowns for restoring endodontically treated molars bonded with two adhesive protocols: an in vitro study

Endocrowns represent a conservative and esthetic restorative alternative to full coverage crowns. They can be constructed using various CAD/CAM materials that can provide a modulus of elasticity similar to that of teeth. The ability to use of such materials in composite blocks that can be easily repaired is also an advantage, provided appropriate bonding performance is ensured. This study, therefore, evaluated the marginal gap and fracture resistance of two CAD/CAM endocrown materials using two bonding protocols. Thirty-two mandibular molars were evaluated in two groups based on the material type: a Cerasmart group (GC America Inc; n = 16) acting as the control and a Ceramill COMP group (Amann Girrbach, Germany; n = 16). These groups were then classified according to the bonding protocol used: a total-etch bonding protocol (n = 8) and a self-etch bonding protocol (n = 8) implemented using RelyX ultimate adhesive resin cement (3M ESPE). The samples were then subjected to aging by simulating a 1-year thermo-mechanical process. The marginal gap results were statistically insignificant across the material and bonding protocol groups before thermo-mechanical aging. Thermo-mechanical aging significantly reduced the marginal gap distance for Ceramill COMP endocrowns cemented using the total-etch protocol (p = 0.002). No statistically significant difference was recorded for the fracture resistance in either the material or bonding protocol groups (p ≥ 0.05). Both materials and bonding protocols can, therefore, be used in the posterior region providing conservative treatment, adequate marginal gap and fracture resistance.

Effect of different CAD-CAM materials on the marginal and internal adaptation of endocrown restorations: An in vitro study

STATEMENT OF PROBLEM

Recent resin-based and ceramic-based computer-aided design and computer-aided manufacturing (CAD-CAM) materials have been used to restore endodontically treated teeth. Adaptation of the restoration is important for clinical success, but studies evaluating the effect of these materials on the adaptation of endocrowns are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of resin-based and ceramic-based materials on the marginal and internal adaptation of endocrowns.

MATERIAL AND METHODS

Forty mandibular molars were divided into 4 groups (n=10); each group was restored with a different CAD-CAM material: group C: hybrid nanoceramic (Cerasmart; GC Corp), group T: fiber-composite material (Trilor; Bioloren Srl), group E: lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent AG), and group V: zirconia-reinforced lithium silicate glass-ceramic (Vita Suprinity; VITA Zahnfabrik GmbH). A digital scan was made with an intraoral digital scanner (TRIOS 3; 3Shape A/S), and endocrowns were milled with a 5-axis milling machine (Coritec 250i; imes-icore GmbH). The replica technique and a stereomicroscope (×70) were used to measure the marginal and internal adaptation of the endocrowns at 32 points. All data were statistically analyzed using 1-way ANOVA and the Tukey honestly significant difference test (α=.05).

RESULTS

Statistical tests showed significant differences among the tested groups (P<.001). The resin-based groups displayed larger discrepancies than the ceramic-based groups. The resin-based groups showed a mean marginal gap larger than the mean internal gap C (P=.009), T (P<.001), whereas the ceramic-based groups showed similar gaps, V (P=.396), E (P=.936). The largest gap was observed at the pulpal floor (P<.001).

CONCLUSIONS

All materials had clinically acceptable internal and marginal gaps (≤150 μm), except for the marginal gap of the Trilor group.

Endocrown restorations for extensively damaged posterior teeth: clinical performance of three cases

The restoration of endodontically treated teeth (ETT) with more than one cusp missing and thin remaining walls is challenging for the general practitioner. The use of posts combined with full coverage restorations is a well-established approach, yet not following the minimal invasive principles of adhesive dentistry. Endocrowns are indirect monoblock restorations that use the pulp chamber of the ETT for retention. In this study the fabrication of 4 endocrowns and their clinical performance will be discussed. Two clinical cases include computer-aided design/computer-aided manufacturing manufactured molar endocrowns (one feldspathic ceramic and one hybrid composite-ceramic restoration) and the other two are dental laboratory manufactured resin composite premolar endocrown restorations. The modified United States Public Health Service criteria were used to assess the clinical behavior of the restorations at different follow up periods. Endocrown restorations present a satisfactory clinical alternative, either by the use of resin composite or glass ceramic and hybrid materials. Specific guidelines with minimal alterations should be followed for an endocrown restoration to be successful. Due to limited evidence regarding the long term evaluation of this restorative technique, a careful selection of cases should be applied.

Strength comparison of anterior teeth restored with ceramic endocrowns vs custom-made post and cores

PURPOSE

The aim of the study was to compare strength of the anterior teeth restored with ceramic endocrowns versus custom-made post and core.

METHODS

The investigation used the finite element analysis. Three 3-D models of maxillary central incisor were created: model A-tooth restored with metal post and core with ceramic crown; model B-tooth with leucite ceramic endocrown; model C-tooth with lithium disilicate ceramic endocrown. Each model was subjected to a 100N force applied at a distance of 5mm from the incisal edge, at the angle of 130° to the long axis of the tooth. The modified von Mises failure criterion was used to evaluate the strength of the dentin, ceramic and resin cement, and Huber-Mises-Hencky failure criterion for cast alloy. Contact stresses in the cement-tissue adhesive interface were calculated.

RESULTS

The lowest stresses occurred in the anterior tooth restored with custom post and core (model A). The mvM stress of 47.5MPa concentrated in leucite ceramic endocrown (model B) and its value was close to the tensile strength of this material. The maximal mvM stresses in the lithium disilicate ceramic endocrown (model C) were 4 times lower than tensile strength of this material. In all cases contact stresses in the adhesive interface under restorations did not exceed the resin cement bond strength to dentin.

CONCLUSIONS

Leucite ceramic endocrowns in incisors may fracture during physiological loading. Endocrowns made of lithium disilicate ceramic are resistant to failure. Posts and prosthetic crowns are still recommended for anterior teeth restorations.

Effect of Preparation Depth on the Marginal and Internal Adaptation of Computer-aided Design/Computer-assisted Manufacture Endocrowns

The aim of the study was to evaluate the effect of preparation depth and intraradicular extension on the marginal and internal adaptation of computer-aided design/computer-assisted manufacture (CAD/CAM) endocrown restorations. Standardized preparations were made in resin endodontic tooth models (Nissin Dental), with an intracoronal preparation depth of 2 mm (group H2), with extra 1- (group H3) or 2-mm (group H4) intraradicular extensions in the root canals (n=12). Vita Enamic polymer-infiltrated ceramic-network material endocrowns were fabricated using the CEREC AC CAD/CAM system and were seated on the prepared teeth. Specimens were evaluated by microtomography. Horizontal and vertical tomographic sections were recorded and reconstructed by using the CTSkan software (TView v1.1, Skyscan).The surface/void volume (S/V) in the region of interest was calculated. Marginal gap (MG), absolute marginal discrepancy (MD), and internal marginal gap were measured at various measuring locations and calculated in microscale (μm). Marginal and internal discrepancy data (μm) were analyzed with nonparametric Kruskal-Wallis analysis of variance by ranks with Dunn's post hoc, whereas S/V data were analyzed by one-way analysis of variance and Bonferroni multiple comparisons (α=0.05). Significant differences were found in MG, MD, and internal gap width values between the groups, with H2 showing the lowest values from all groups. S/V calculations presented significant differences between H2 and the other two groups (H3 and H4) tested, with H2 again showing the lowest values. Increasing the intraradicular extension of endocrown restorations increased the marginal and internal gap of endocrown restorations.

Endocrowns: review

The ideal restoration of endodontically treated teeth (ETT) has been widely and controversially discussed in the literature. Prevention of healthy dental structure is essential to help mechanical stabilization of tooth-restoration integrity, increase the amount of suitable surfaces for adhesion and thus positively affect the long-term success. ETT are affected by a higher risk of biomechanical failure than vital teeth. With the development of adhesive systems, the need for post-core restorations is also reduced. Especially for restoration of excessively damaged ETT, endocrowns have been used as an alternative to the conventional post-core and fixed partial dentures. Compared to conventional methods, good aesthetics, better mechanical performance, and less cost and clinic time are the advantages of endocrowns.

Influence of proximal box elevation on the marginal quality and fracture behavior of root-filled molars restored with CAD/CAM ceramic or composite onlays

OBJECTIVES

This study investigated the influence of proximal box elevation (PBE) with composite resin when applied to deep proximal defects in root-filled molars with mesio-occluso-distal (MOD) cavities, which were subsequently restored with computer-aided designed/computer-aided manufacturing (CAD/CAM) ceramic or composite restorations.

MATERIALS AND METHOD

Root canal treatment was performed on 48 human mandibular molars. Standardized MOD cavities were prepared with the distal box located 2 mm below the cemento-enamel junction (CEJ). The teeth were randomly assigned to one of four experimental groups (n = 12). In groups G1 and G2, the distal proximal box was elevated up to the level of the CEJ with composite resin (PBE). No elevation was performed in the remaining two groups (G3, G4). CAD/CAM restorations were fabricated with feldspathic ceramic (Vita Mark II, CER) in groups G1 (PBE-CER) and G3 (CER) or with resin nano-ceramic blocks (Lava Ultimate, LAV) in groups G2 (PBE-LAV) and G4 (LAV). Replicas were taken before and after thermomechanical loading (TML; 1.2 Mio cycles; 49 N; 3,000 thermocycles between 50 °C and 5 °C). Following TML, load was applied until failure. Fracture analysis was performed under a stereomicroscope (×16). Marginal quality before and after TML (tooth restoration, composite restoration) was evaluated using scanning electron microscopy (×200).

RESULTS

After TML, lower percentages of continuous margins were observed in groups G1-G3 compared with pre-TML assessments; however, the differences were not statistically significant. For group G4-LAV, the marginal quality after TML was significantly better than in any other group. The highest mean fracture value was recorded for group G4. No significant difference was found for this value between the groups with PBE compared with the groups without PBE, regardless of the material used. The specimens restored with ceramic onlays exhibited fractures that were mainly restricted to the restoration while, in teeth restored with composite onlays, the percentage of catastrophic failures (fractures beyond bone level) was increased.

CONCLUSION

PBE had no impact on either the marginal integrity or the fracture behavior of root canal-treated mandibular molars restored with feldspathic ceramic onlays. CAD/CAM-fabricated composite onlays were more favorable than ceramic onlays in terms of both marginal quality and fracture resistance, particularly in specimens without PBE.

CLINICAL RELEVANCE

Composite onlays with or without PBE may be a viable approach for the restoration of root-filled molars with subgingival MOD cavities.