Fracture Resistance Values Research Articles

An in vitro comparison of the fracture resistance of MOD inlay restorations using different lithium disilicates

Objective: The objective of this study was to evaluate and compare the fracture resistance of MOD inlay preparations restored with two different lithium disilicate glass ceramics. Materials and Methods: Standardized MOD inlay cavities were prepared on 64 human permanent premolar teeth and divided into two groups to be restored with lithium disilicate glass-ceramic materials, i.e. Group I with IPS e.max Press HT and Group II with Shofu Vintage LD Press T. The fracture resistance was assessed using a universal testing machine and recorded in Newtons (N). Statistical analysis was done using SPSS software (Version 17.0, IBM, USA). P <0.05 was set as a statistically significant level. Unpaired Student’s t-test was used to compare the fracture resistance values of both groups. Results: The mean fracture resistance value obtained for Group I (IPS e.max Press HT) was 565.04 N while that obtained for Group II was 732.75 N. Statistically significant difference was found in this intergroup comparison (P = 0.002). Conclusion: The fracture resistance of MOD inlay preparations restored with Vintage LD Press T (Shofu) was significantly higher than those restored with IPS e.max Press HT (Ivoclar Vivadent).

Effect of preparation design on fracture resistance of molars restored with occlusal veneers of different CAD-CAM materials: an in vitro study

BackgroundOcclusal veneer had been evaluated for mechanical properties using lithium disillicate. However, studies evaluating the mechanical properties of occlusal veneer with different preparation designs and ceramic materials are lacking. So, this in vitro study aimed to evaluate the fracture resistance of occlusal veneers with two designs fabricated from two different ceramic materials.Material and methodsFourty mandibular third molars were distributed to 2 groups (n = 20) according to preparation design: group (O) anatomical occlusal reduction and group (OA) anatomical occlusal and 1 mm axial reduction. Each group was additionally subdivided into two subgroups (n = 10) according to ceramic materials; in subgroup X, lithium disilicate (e.max CAD, Ivoclar AG, Schaan, Liechtenstein) was used, and in subgroup S, zirconia-reinforced lithium silicate (ZLS) (Vita Suprinity, VitaZahnfabrik, Bad Säckingen, Germany) was used. All specimens were cemented with a light-cure resin cement (Choice 2, Bisco, Schaumburg, USA). 5000 thermocycles were applied to all specimens with both temperatures of 5 °C and 55 °C in two water baths; the dwell time was 30s at each bath, and the transfer time was 10s. Then all specimens were subjected to a fatigue simulation under dynamic loading of 200 N for 250,000 cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to evaluate the fracture strength with a crosshead speed of 1 mm/min. All data were analyzed statistically by using a two-way ANOVA, and for some violations of assumptions, these results were compared with those obtained by the nonparametric test (Scheirer Ray Hare) (α = 0.05).ResultsA statistically significantly higher fracture resistance in the ‘OA’ (3389 N) compared to the ‘O’ (2787 N) group regardless of the ceramic material (P < .001) and a statistically significantly higher fracture resistance in the ‘X’ (3295 N) compared to the ‘S’ (2881 N) regardless of the preparation design (P = .015).ConclusionsFor occlusal veneers, all preparation designs and materials (such as Vita Suprinity and e.max CAD) had clinically acceptable fracture resistance values that were greater than the maximal biting forces. On the other hand, the e.max CAD with occlusal veneer, including axial reduction design, demonstrated the maximum fracture resistance value. Finally, no relationship between fracture strength and mode of failure was found.

Influence of final irrigation with titanium dioxide and silver nanoparticles on the fracture resistance of endodontically treated roots

BackgroundTitanium dioxide (TiO2NP) and silver nanoparticles (AgNPs) have been recognized for their ability to enhance the structural integrity of dental materials. This study aimed to compare the influence of these nanoparticles on the structural resilience of treated root canals. Materials and MethodsThe crowns of 75 undamaged central incisors were sectioned below the cemento-enamel junction to achieve a consistent root length of 16 mm. The root canals were prepared using K3 files up to size 40 with a 6 % taper. The specimens were then divided into five groups (n = 15), each subjected to a final irrigation protocol with one of the following solutions: normal saline, 2 % chlorhexidine (CHX), 17 % EDTA combined with 2.5 % sodium hypochlorite (NaOCl), 17 % EDTA with 0.1 % silver nanoparticles (AgNPs), and 17 % EDTA with 0.1 % titanium dioxide nanoparticles (TNPs). After obturation with gutta-percha and sealer, fracture resistance (FR) was evaluated. The data were analyzed using one-way ANOVA and Tamhane’s post hoc test (p < 0.050). ResultsThe lowest fracture resistance (FR) was observed in the group treated with ethylenediaminetetraacetic acid (EDTA) combined with sodium hypochlorite (NaOCl), followed by the groups irrigated with normal saline and chlorhexidine (CHX), with no statistically significant difference between the latter two groups (p > 0.05). There was also no significant difference in FR between the CHX and saline groups (p > 0.05). In contrast, irrigation with silver nanoparticles (AgNPs) and titanium dioxide nanoparticles (TNPs) resulted in significantly higher fracture resistance compared to the other solutions tested (p < 0.050). ConclusionThe fracture resistance of endodontically treated roots was significantly improved when the final irrigation sequence included AgNPs and TNPs nanoparticles. In contrast, sodium hypochlorite (NaOCl) yielded the lowest fracture resistance value.

Comparative Evaluation of Fracture Strength of Implant Supported Crown Fabricated from CAD/CAM and 3D Printed Resin Matrix Ceramic

Objective: To compare fracture strength of screw-retained implant-supported crown of resin matrix ceramic when fabricated using CAD/CAM and 3D printing Material and method: vericom Mazic® Duro (CAD/CAM Nano Hybrid Ceramic) was used as particle-filled composite CAD/CAM material, saremco Print Crowntec (3D printable resins-based) as 3D printed composite material, and the control group was composed of IPS e.max. ZirCAD ivoclar vivadent (zirconia) was used to fabricate mandibular first molar screw-retained, implant-supported crowns. After the fabrication, the crowns were cemented with the Rely X U200 self-adhesive resin cement (3M ESPE, Germany) on stock abutments tightened to analogs embedded in acrylic resin. Finally, all crowns were subjected to a fracture resistance test. fracture strength was evaluated by using one–way ANOVA with Chi-square used for the association between the modes of fracture. Result: The results showed that there were significant differences between all the groups used, the control group (Group zirconia) was significantly higher, as the mean was equal to 6391 N. Followed by Group vericom (cad/cam) with a mean of 2558 N, then Group seramco (3D printing) with a mean of 817.92 N. Dunnett T3 test showed statistically significant differences in fracture resistance between the three groups. There was no significant difference between the modes of fracture and the methods. Conclusion: Screw-retained implant-supported crowns manufactured by CAD/CAM technique had better fracture resistance value than those of the 3D printed technique. Clinical Relevance: resin matrix ceramic is a possible substitute for zirconia in an implant-supported crown

Effect of different preparation designs and material types on fracture resistance of minimally invasive posterior indirect adhesive restorations.

To evaluate the impact of various preparation designs and the material type on fracture resistance of minimally invasive posterior indirect adhesive restorations after aging using a digital standardization method. One-hundred sixty human maxillary premolars free from caries were assigned into 16groups (n=10): bevel design on enamel substrate with mesial box only (VEM), butt joint design on enamel substrate with mesial box only (BEM), bevel design on enamel substrate with mesial and distal box (VED), butt joint design on enamel substrate with mesial and distal box (BED), bevel design on dentin substrate with mesial box only (VDM), butt joint design on dentin substrate with mesial box only (BDM), bevel design on dentin substrate with mesial and distal box (VDD), and butt joint design on dentin substrate with mesial and distal box (BDD). Each group was restored with pressable lithium disilicate (LS2) or disperse-filled polymer composite (DPC) materials. Adhesive resin cement was used to bond the restorations. The specimens were aged for 10,000 thermal cycles (5°C and 55°C), then 240,000 chewing cycles. Each specimen was subjected to compressive axial load until failure. A two-way analysis of variance (ANOVA) test followed by a post hoc Tukey test was used to analyze the data (α=0.05). The two-way ANOVA test revealed a significant difference among designs (p<0.001) and materials (p<0.001) with no interaction effect (p=0.07) between the variables. The Post hoc Tukey test revealed that the VEM group exhibited the highest mean fracture resistance value, while the BDM group had the lowest. The LS2 groups showed the highest mean fracture resistance values. The DPC groups showed a restorable fracture pattern compared to the LS2 groups. Bevel and butt joint designs with mesial or distal boxes are recommended for conservative posterior indirect adhesive restorations in premolar areas. Enamel substrate improved load distribution and fracture resistance. DPCs have restorable failure patterns, while pressed LS2 may harm underlying structures.

Fracture Resistance of Space Maintainers Produced Using 3D Printable Materials.

This study aimed to evaluate the fracture resistance of space maintainers (SMs) produced using 3D-printable materials (metal, resin and polyetheretherketone [PEEK]) after thermal aging and compare them with conventional space maintainers. A standardised typodont model for paediatric dentistry was utilised, and band and loop space maintainers were designed digitally using computer-aided design (CAD) technology. Four groups were established: Conventional, 3D printed metal, 3D printed resin, and 3D printed PEEK. Fracture resistance was assessed after 10,000 thermal cycles, simulating oral conditions. Fracture tests were conducted using a universal testing machine, applying vertical force to the band and loop junction until fracture. Statistical analyses were performed using one-way ANOVA and the Tukey HSD test (P<0.05). Although the fracture resistance values showed that metal, resin, and PEEK 3D printed band and loop space maintainers can be acceptable clinically, the permanent resin may be preferable to printable material because of their aesthetic properties.

Phase-field modelings of fracture investigate the influence of interfacial effects on damage and optimal material distribution in brittle inclusion-matrix structures

This present work uses the phase-field modelings to investigate the influence of interfacial effects on damage and mechanical behavior, as well as the optimal distribution of the inclusion shape within brittle inclusion-matrix structures in various typical cases. These two constituent phases in the structures are assumed to be either isotropic or anisotropic. To achieve these goals, this work will: (i) use the phase-field modelings either considering or neglecting interfacial debonding, and the anisotropic phase-field modeling; (ii) determine and incorporate the strain tensor orthogonal decompositions into each specific phase-field modeling to enhance the accuracy and effectiveness of the simulation methods; (iii) combine the phase-field modelings with the BESO topology optimization algorithm to analyze the influence of interfacial effects on relationship curves and the optimal distribution of the inclusion shape. Through proposed numerical examples, it is demonstrated that the interfacial effects strongly influence crack paths, behavior curves, and optimal material distribution in structures. When considering interfacial effects, cracks are almost unable to penetrate into the inclusion phase. However, when neglecting interfacial effects, cracks propagate into the inclusion phase. This reason makes the structure more difficult to damage than when considering the interfacial effects, as evidenced by greater peak load values in behavior curves and greater total fracture resistance of the material. Especially in the example of inclusion phase optimization, the total fracture resistance value of the case neglecting interfacial effects is more than 107.9% greater than that considering interfacial effects.

The effect of different materials and cavity designs on fracture resistance of ceramic partial coverage.

Two intra-coronal preparation designs with varying extensions of cuspal coverage can perform differently regarding their fracture resistance against introral forces. Two materials (IPS e-max CAD [EX], VITA ENAMIC [EN]), and two different preparation designs (EX-D1), (EX-D2), (EN-D1), and (EN-D2) were investigated to compare their fracture resistance. A total of 40 (n = 40) caries free human mandibular molars were used. All the prepared samples were scanned using CEREC Omnicam scanner and the preparations were checked by the software for any sharpness and undercuts before restoration designing and fabrication. All restorations were milled using Cerec MCXL 4.4 milling machine. Duo-Link resin cement was used for cementation. After thermocycling and chewing simulation, all samples were loaded in the Universal testing machine in order to evaluate fracture resistance of all samples. Fracture resistance testing revealed that e-max CAD (2134 N) showed statistically significantly higher mean fracture resistance values than Vita Enamic (1728 N). On the other hand, there was no statistically significant difference between mean fracture resistances between the two tested designs. Within the confines of this investigation, it can be said that although preparation design had no appreciable impact on fracture resistance, the CAD/CAM ceramic material utilized did. When restoring compound cavitties indirectly; a conservative defect oriented approach should be used. Glass Ceramic are prefered as restorative material.

Pre-Sealing of Endodontic Access Cavities for the Preservation of Anterior Teeth Fracture Resistance.

Sodium hypochlorite solution (NaOCl) is an effective canal irrigant but interferes with the mechanical features of dentin and the bonding capability of adhesives when restoring endodontically treated teeth. This study evaluated whether access cavity resin sealing before using canal irrigant would augment the resistance of endodontically treated anterior teeth against fracture. Sixty maxillary incisors underwent endodontic treatment in five groups (n = 12). Irrigation with 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) was performed in all groups except for Group 5. After root canal obturation, in Group 1, the access cavity was kept unrestored. In Group 2, immediate restoration after obturation was achieved. For Group 3, delayed restoration after 1 week was provided. In Group 4 (pre-sealed), before canal irrigation, the dentin surface of access cavities was sealed using self-adhesive composite resin (Vertise Flow) and then restored after obturation. In Group 5, which was saline irrigated, immediate restoration was performed. After storage and thermal cycling for 5000 cycles at 5°C-55°C with a dwell time of 15 s and a transfer time of 5 s, teeth were statically loaded by a universal testing machine until a fracture occurred. Data were collected as the fracture resistance (FR) and analyzed using the one-way analysis of variance and Tukey's tests. FR significantly differed between all groups (p < 0.001). The lowest FR was recorded in the unrestored group (284 ± 86 N), which was not statistically different from the immediately restored group (p = 0.065). The pre-sealed group exhibited the highest FR value (810 ± 127 N, p ≤ 0.02 vs. other groups). The FR of the saline-irrigated and delayed restored groups was almost similar (p = 0.13). NaOCl/EDTA irrigation resulted in an adverse effect on FR. Delayed restoration could reduce this adverse effect. Access cavity pre-sealing with flowable composites led to a higher FR than conventional methods and may be considered an effective step during treatment procedures.

Fracture resistance of ultratranslucent multilayered zirconia veneers with different facial thicknesses.

To assess the fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ultratranslucent multilayered zirconia (5Y-YZP) veneers with varying facial thickness. Sixty translucent zirconia veneers were designed and milled using a chairside CAD/CAM system for maxillary central incisors. The butt joint incisal veneer tooth preparations consisted of 1.00 mm incisal reduction, 0.40 mm chamfer margin, and three different facial reductions; 0.50, 0.75, and 1 mm, respectively. The ceramic veneers were cemented to printed resin dies and subjected to thermal cycling. Subsequently, the restorations were loaded with compressive loading force, and fracture occurrences were recorded. Scanning electron microscope (SEM) images of the fractured specimens were captured. The fracture resistance varied among the veneers with different facial thicknesses. Ultratranslucent zirconia veneers with a facial thickness of 1.00 mm exhibited the highest fracture resistance values (742.15 N), followed by those with 0.75 mm facial thickness (673 N). Minimally invasive veneers with 0.50 mm thickness displayed similar fracture resistance as thicker veneers with 0.75 mm. However, veneers with 1.00 mm thickness displayed the highest values. SEM fracture patterns for 0.50 and 0.75 mm display similar and fewer crack lines than 1.00 mm veneers. RESEARCH HIGHLIGHTS: Minimally invasive zirconia veneers exhibit similar fracture resistance to thicker veneers.

Effect of preparation design on the fracture resistance and fracture patterns of 3D printed one-piece endodontic crowns

Statement of problemThe impact of various preparation designs on the fracture resistance and fracture type of mandibular premolars restored with 3 dimensionally (3D) printed, 1-piece endodontic crowns remains unclear. PurposeThe purpose of this study was to investigate the effect of different preparation designs on the fracture resistance and fracture patterns of mandibular premolars restored with 3D printed 1-piece endodontic crowns after thermal aging. Material and methodsForty-five freshly extracted mandibular premolars received 3 different preparation designs: with at least 2 intact cuspal walls (2CW), with only 1 intact cuspal wall (1CW), and no cuspal wall present (NoCW). One-piece endodontic crowns were designed by using a computer-aided design (CAD) software program, 3D printed, cemented to the prepared teeth with self-adhesive resin cement, and thermocycled between 5 °C and 55 °C in artificial saliva. Subsequently, all specimens were subjected to a fracture test. The results were statistically analyzed using 1-way ANOVA (α=.05), and fracture types of all specimens were examined using a light microscope. ResultsThe analysis of fracture resistance values across separate designs revealed no statistically significant differences (P>.05). Mean fracture resistance values were 724.5 N in 2CW, 713 N in 1CW, and 861 N in NoCW. In 2CW and 1CW, the 1-piece endodontic crowns mostly displayed Type III fractures, whereas those in NoCW exhibited a combination of Type II and Type III fractures. ConclusionsThe mandibular premolar 1-piece endodontic crowns tested in this study exhibited similar fracture resistance and type of fracture with different preparation designs.

Multimethod Analysis of a Novel Multi-coloured Heat-treated Nickel-Titanium Rotary System: Design, Metallurgy, Mechanical Properties, and Shaping Ability

IntroductionThis study aimed to compare a new multicolored rotary system with four heat-treated rotary instruments using the multimethod approach. MethodsThree-hundred instruments of RCS Rainbow, Rotate, RaCe EVO, OneCurve, and ProTaper Ultimate systems were evaluated regarding their design (stereomicroscopy, scanning electron microscopy, and 3D surface scanning), metallurgy, and mechanical performance (cyclic fatigue, torsional resistance, bending and buckling resistance, and cutting ability). Unprepared surfaces after canal preparation of maxillary molars were evaluated using micro-computed tomography. Kruskal-Wallis and one-way analysis of variance post hoc Tukey tests were used for statistical comparisons (α = 5%). ResultsInstruments exhibited variations in active blade length, number of spirals, and cross-sectional designs. RCS Rainbow showed specific phase transformation temperatures, highest bending (400.5gf) and buckling (286gf) resistance values, and lowest mean angle of rotation (529°) (P < .05). OneCurve exhibited superior cutting ability (8.4 mm) and longer time to fracture (112s). RaCe EVO displayed the lowest time to fracture (51s), maximum torque (1.2 N.cm), buckling (174gf), and bending resistance (261gf) values (P < .05). ProTaper Ultimate showed the highest torque (1.6 N.cm) and angle of rotation (611°) (P < .05), while its bending load (262gf) was comparable to RaCe EVO (P > .05). Rotate instrument showed intermediate values in the mechanical tests. No difference was observed regarding the unprepared canal surfaces (P > .05) ConclusionsRCS Rainbow demonstrates a trade-off between flexibility and other mechanical properties. Its dimensions exceeded those of other instruments, affording it higher torque resistance, yet concurrently reducing its flexibility, angle of rotation, and cutting ability. OneCurve stands out as a well-balanced choice by integrating geometric design and mechanical performance.

In Vitro Assessment of the Fracture Resistance of Different Prosthodontic Materials for Fixed Dental Prostheses.

Fixed dental prostheses (FDPs) are commonly used in prosthodontics to restore missing teeth and improve oral function and esthetics. The selection of prosthodontic materials significantly impacts the fracture resistance of FDPs, thus influencing their clinical success. This study aimed to assess the fracture resistance of different prosthodontic materials commonly used in FDPs through in vitro testing. Thirty standardized FDP specimens were fabricated using three different materials: Monolithic zirconia, heat press lithium disilicate, and metal ceramic. Each group consisted of ten specimens. The specimens were subjected to standardized loading using a universal testing machine until fracture occurred. Fracture resistance values were recorded in Newtons (N) and statistically analyzed using one-way analysis of variance (ANOVA) followed by post-hoc Tukey tests. The mean fracture resistance values for the three materials were as follows: zirconia, 1450 N; lithium disilicate, 1200 N; and metal ceramic, 950 N. Statistical analysis revealed a significant difference among the groups (P < 0.05). Post hoc Tukey tests indicated that zirconia exhibited significantly higher fracture resistance compared to lithium disilicate and metal ceramic (P < 0.05). However, there was no significant difference in fracture resistance between lithium disilicate and metal-ceramic groups (P > 0.05). Within the limitations of this in vitro study, zirconia demonstrated the highest fracture resistance among the tested materials for FDPs, followed by lithium disilicate and metal ceramic. The findings highlight the importance of material selection in achieving optimal clinical outcomes and longevity of fixed dental prostheses.

In-vitro evaluation of fracture resistance of teeth restored with different high-viscosity glass ionomer restorative materials and bulk-fill composite resins

ObjectivesThis study aimed to evaluate the effect of restorations made with a glass-hybrid restorative system (GHRS), a high-viscosity glass ionomer restorative material (HVGIC), a high-viscosity bulk-fill composite resin (HVB), a flowable bulk-fill composite resin (FB), and a nanohybrid composite resin (NH), which are commonly preferred in clinical applications on the fracture resistance of teeth in-vitro.Materials and methodsOne hundred intact human premolar teeth were included in the study. The teeth were randomly divided into ten groups (n = 10). No treatment was applied to the teeth in Control group. Class II cavities were prepared on the mesial surfaces of the remaining ninety teeth in other groups. For restoration of the teeth, a GHRS, a HVGIC, a HVB, a FB, and a NH were used. Additionally, in four groups, teeth were restored using NH, GHRS, and HVGIC with open and closed-sandwich techniques. After 24 h, fracture resistance testing was performed. One-way ANOVA and Tukey HDS tests were used for statistical analysis of the data.ResultsThe fracture resistance values of Control group were statistically significantly higher than those of GHRS, HVGIC, FB, NH, HVGIC-CS, GHRS-OS, and HVGIC-OS groups(p < 0.05). There was no statistically significant difference observed between the fracture resistance values of Control, HVB, and GHRS-CS groups (p > 0.05).ConclusionIt can be concluded that the use of HVB and the application of GHRS with a closed-sandwich technique may have a positive effect on the fracture resistance of teeth in the restoration of wide Class II cavities.Clinical relevanceThe use of high-viscosity bulk-fill composite resin and the application of glass-hybrid restorative system with the closed-sandwich technique in the restoration of teeth with wide Class II cavities could increase the fracture resistance of the teeth.

The Effect of Thermocycling and Mechanical Loading on the Fracture Resistance of Graphene and All-Ceramic Anterior Crowns.

Introduction Fixed prosthodontic treatment involves the replacement of missing tooth structures with a variety of materials. Several newer metal-free ceramics have been developed in recent years to meet patients' aesthetic needs. The long-term performance of all ceramics, however, is unknown, necessitating a continuous evaluation of the materials' strength. Aim The aim of this study was to compare and evaluate the fracture resistance of IPS E max pressable crowns and graphene crowns, which are luted with Rely X U200 self-adhesive resin cement on the respective dies, as well as thermocycling of IPS E max pressable crowns and thermocycling of graphene crowns. The current review was conducted as an in vitro examination at the Division of Prosthodontics, GSL Dental School, Rajahmundry, Andhra Pradesh, India. Materials and methods On a typodont tooth, a shoulder finish line design was prepared and incisal reduction was performed. The tooth was scanned, designed, and milled to produce 18 metal dies made of cobalt-chrome alloy. These metal dies produced a total of (n=36) all-ceramic crowns, which were divided into two groups based on crown type: 18 IPS E max crowns and 18 graphene crowns. The participants were once again divided into two subgroups within each group, with the purpose of assessing fracture resistance. This evaluation was conducted using a universal testing machine both before and after subjecting the specimens to thermocycling. The obtained data were sent for statistical analysis. Results Fracture resistance values were reduced after thermocycling of both IPS E max and Graphene crowns. Without thermocycling, the fracture resistance values of IPS E max crowns were higher than those of graphene crowns. Conclusions The fracture resistance of IPS E max crowns exhibited a statistically significant increase when compared to graphene crowns. Additionally, it was shown that the fracture resistance of both materials was reduced upon exposure to thermocycling.

Fracture resistance of additively or subtractively manufactured resin-based definitive crowns: Effect of restorative material, resin cement, and cyclic loading

ObjectiveTo evaluate how restorative material, resin cement, and cyclic loading affect the fracture resistance of resin-based crowns fabricated by using additive or subtractive manufacturing. MethodsA right first molar crown standard tessellation language (STL) file was used to fabricate 120 crowns from one subtractively manufactured polymer-infiltrated ceramic network (SM) and two additively manufactured resin composites (AM-B and AM-S) (N = 40). These crowns were randomly divided into 4 groups within each material according to the dual-polymerizing resin cement to be used (RX and PN) and the aging condition (n = 10). After cementation, the crowns without cyclic loading were subjected to fracture testing, while the others were first cyclically loaded (1.7 Hz, 1.2 million cycles, and 49-N load) and then subjected to fracture testing. Data were analyzed with generalized linear model analysis (α = .05). ResultsFracture resistance of the crowns was affected by material, resin cement, and cyclic loading (P ≤ .030). However, none of the interactions significantly affected fracture resistance of tested crowns (P ≥ .140). Among tested materials, SM had the highest fracture resistance, whereas AM-B had the lowest (P ≤ .025). RX led to higher fracture resistance, and cyclic loading decreased the fracture resistance (P ≤ .026). SignificanceTested materials can be considered reliable in terms of fracture resistance in short- or mid-term (5 years of intraoral simulation) when used for single molar crowns with 2 mm occlusal thickness. In the long term, polymer-infiltrated ceramic network crowns cemented with RelyX Universal may provide promising results and be less prone to complications considering higher fracture resistance values obtained.

Fracture resistance of endodontically treated maxillary premolars using indirect and direct composite onlays: A comparative study

ABSTRACT Aim: To evaluate and compare the fracture resistance of endodontically treated maxillary teeth using the same material as indirect and direct composite onlays and their modes of fracture. Materials and Methods: Ninety maxillary premolars were divided into six groups (n = 15) out of which 15 teeth were kept intact (negative control, Group 1). In the remaining 75 teeth, endodontic treatment was done and standardized mesio-occlusal-distal cavities were prepared. Fifteen teeth were kept unrestored (positive control, Group 2). The rest of the teeth were divided according to the type of restorations and the restorative material; Group 3: Ceram X sphereTEC™ one direct composite onlay, Group 4: Ceram X sphereTEC™ one indirect composite onlay, Group 5: Filtek Z 350 XT direct composite onlay, and Group 6: Filtek Z 350 XT indirect composite onlay. All the specimens were subjected to thermocycling and cyclic loading. The fracture resistance test was performed with the help of a universal testing machine and their modes of fracture were evaluated. Results: Mean fracture resistance values in the decreasing order are as: 1487.33N for Group 6, 1104.57N for Group 4, 933.87N for Group 1, 799.13N for Group 5, and 688.73N for Group 3, 265.23N for Group 2. Mean fracture resistance of Groups 6 and 4 was found to be significantly higher than Groups 1, 2, 3, and 5. Furthermore, there was a significant difference between Groups 1 and 3. Groups 1, 3, 4, 5, and 6 showed more number of favorable/restorable fractures, whereas Group 2 showed more unfavorable/unrestorable fracture. Conclusion: The indirect technique of fabrication of onlays improved the fracture resistance of endodontically treated maxillary premolars.

Effect of different intracanal medicaments combined with chitosan nanoparticles on microhardness and fracture resistance of root dentin – An in vitro study

Abstract Introduction: Chitosan nanoparticles (CSN) are widely used for endodontic disinfection; however, their combination with other intracanal medicaments is least studied; therefore, this study aims to evaluate the effect of various intracanal medicaments incorporated with 0.2% CSN on root dentin microhardness and fracture resistance. Materials and Methods: Fifty extracted human single-rooted premolars were cleaned, decoronated, and standardized to 13 mm root length. After access opening and working length determination, specimens were instrumented with ProTaper rotary files till apical size F3 and alternatively irrigated with 5 ml of 2.5% sodium hypochlorite and normal saline (NS). Final irrigation was done with 5 ml of 1% phytic acid. The specimens were allocated randomly into five groups (n = 10), followed by placement of intracanal medicament for 1 week as follows. Group 1 – 0.2% CSN, Group 2 – Calcium hydroxide (Ca[OH] 2) + 0.2% CSN, Group 3 – Triple antibiotic paste (TAP) + 0.2% CSN, Group 4 – Propolis + 0.2% CSN, and Group 5 – Chlorhexidine gluconate (CHX) + 0.2% CSN. The specimens were then rinsed with NS and 3 mm coronal portion of each specimen was horizontally sectioned to create dentin blocks that were further split vertically and tested for Vickers microhardness (n = 10). The remaining root segment of each specimen was then vertically embedded in an acrylic block and evaluated for fracture resistance (n = 10) under a universal testing machine. The data acquired were statistically assessed using one-way ANOVA and posthoc Tukey tests (P &lt; 0.05). Results: Propolis incorporated with 0.2% CSN showed the highest microhardness and fracture resistance values followed by CHX + 0.2% CSN, TAP + 0.2% CSN, Ca(OH)2 + 0.2% CSN, and least in 0.2% CSN alone. Conclusion: Intracanal medicaments incorporated with 0.2% CSN exhibited a synergetic effect on microhardness and fracture resistance of endodontically treated teeth; however, propolis with 0.2% CSN exhibited higher microhardness and fracture resistance of root dentin.

Effect of aging on the fracture resistance and microleakage of CAD-CAM-produced ceramic inlays

Aim: The aim of the study was to evaluate the fracture resistance and microleakage of different CAD-CAM inlay restorations. Methodology: Inlay restorations from nine restorative materials as monolithic zirconia (TZI), resin nano ceramic (LU), hybrid ceramic (VE), feldspathic ceramic (CB), zirconia reinforced lithium silicate (VS), lithium disilicate (e.max), leucite reinforced glass ceramic (Emp), resin ceramic (GCS), and conventional composite resin (CR) were used (n=10). For evaluating the fracture resistance, restorations were cemented to resin teeth and subjected to thermomechanical aging. The data of fracture resistance were analyzed using One-way Analysis of Variance (ANOVA) and Games-Howel tests (a=0.05). For evaluating the microleakage, restorations were cemented on human teeth and subjected to thermocycling. The teeth were vertically sectioned into two parts and microleakages were assessed as yes or no. Results: The highest and lowest fracture resistance values were found in TZI and LU groups, respectively (p&gt;0.05). The most frequent microleakage was observed in TZI and CR groups, and the least microleakage was seen in the VE group. Microleakage was frequently found in cervical surfaces and followed by occlusal, axial, and pulpal surfaces. Conclusion: Hybrid ceramics showed similar fracture resistance with the monolithic zirconia; besides, the lowest microleakage was observed for these ceramics. Hybrid ceramics may be a good alternative for inlay restorations. How to cite this article: Bankoğlu Güngör M, İnal CB, Hürbağ M, Toksoy B, Turhan Bal B, Karakoca Nemli S. Effect of aging on the fracture resistance and microleakage of CAD-CAM-produced ceramic inlays. Int Dent Res 2024;14(1):10-18. https://doi.org/10.5577/intdentres.324

Fracture resistance of CAD/CAM milled versus direct hand-made interim laminate veneers

BackgroundComparative studies of interim veneer restorations crafted using subtractive computer-aided manufacturing (s-CAM) milling technology and traditional direct hand-made approaches are needed. PurposeThis comparative in vitro study evaluated the fracture resistance of two types of provisional veneer restorations for maxillary central incisors: milled (s-CAM) and traditional direct hand-made bis-acryl veneers. Materials and methodsFifty maxillary right central incisor veneers (25 specimens per group) were fabricated and divided according to the fabrication method: (1) s-CAM milled (Structure CAD, VOCO Dental); and (2) hand-made (Protemp Plus, 3M). The restorations were cemented onto 3D-printed resin dies using temporary cement and subjected to 1000 cycles of thermal cycling between 5° and 55 °C. These restorations subsequently were subjected to compressive loading until fracture occurred. Images of the fractured samples were captured using a scanning electron microscope (SEM). Statistical analysis was performed using the one-way ANOVA test and the Mann-Whitney U test. ResultsSignificant differences (p < 0.001) in the fracture resistance were observed between the two groups. s-CAM milled interim veneers displayed higher fracture resistance values (439.60 ± 26 N) compared to the traditional method (149.15 ± 10 N). ConclusionThe manufacturing method significantly influences the fracture resistance of interim veneer restorations. s-CAM interim laminate veneer restorations for maxillary central incisors exhibit a fracture resistance superior to that of the traditional method using bis-acryl.Clinical relevanceClinicians should consider CAD/CAM milled veneers for scenarios demanding long-term interim restoration and the withstanding of high occlusal forces.