Fracture Resistance Test Research Articles

"Effect of mid-root perforation and its repair on stress distribution and fracture resistance: a 3D finite element analysis and in vitro study".

to assess and compare the effect of mid-root perforation repair using Biodentine and Portland cement in single-rooted endodontically treated mandibular premolars in terms of stress distribution using finite element analysis (FEA) and fracture resistance test. In the FEA, an extracted human mandibular premolar tooth was scanned using cone beam computed tomography, and a 3-dimensional (3D) solid model was created. A sound tooth model (ST), an endodontically treated model (ET), an instrumented and mid-root perforated and repaired by Biodentine model (BM), and perforated and repaired by Portland cement model (PCM) were the 4 models simulated. A vertical force of 300N on the occlusal plane was applied. Evaluation of von Mises stress distribution and maximum displacement were investigated. In the fracture resistance in vitro study, 28 extracted premolars were selected and randomized into 4 groups, (n = 7), (A) is the negative control intact group, (B) is the positive control of endodontically treated group, (C) is mid-root perforated and repaired by Biodentine group and (D) is mid-root perforated and repaired by Portland cement. All Teeth were instrumented except for group A, group B was obturated while groups C and D were instrumented, perforated, repaired, and obturated. All groups were restored coronally except group A. Fracture force was measured; subsequently, the fracture repairability was evaluated. Finally, the data were statistically evaluated using one-way analysis of variance (ANOVA); the significance level was set at P ≤ 0.05 and the repairability of teeth after fracture was correlated to the maximum loading using Pearson's coefficient tests. In FEA, Maximum von Mises stress was descending assorted as 121.1MPa for ET, 115.6MPa for BM and PCM, and 109MPa for ST, and in the mid-root area or perforation site were 20MPa for PCM, 16.17MPa for BM, 10.16MPa for ET and 8.1MPa for ST while the Maximum Displacement was descending assorted as 0.0179mm for ET, 0.0169mm for BM and PCM and 0.0151mm for ST. In the fracture resistance test, Group A showed higher fracture resistance than other groups significantly. There was a non-significant difference between Groups B, C, and D. There was also an insignificant correlation between the maximum loading and the repairability of the tooth after fracture. FEA and fracture resistance test showed that the 2 repair materials are acceptable and recommended in iatrogenic mid-root perforation.

Investigation of fracture resistance with different diameters of polyetherketoneketone posts and cores material: A pilot study

Objectives: The primary objective of this study is to investigate the resistance to fracture of Polyetherketoneketones PEKK, used as post and core by fabrication in different diameters in the canal, and comparing the test results for each group. Methods: Thirty extracted mandibular premolars were selected, endodontically treated and prepared to receive the post and cores milled from polyetherketoneketone disk. The specimens were randomly divided into five groups (n = 6) respectively: group 1 received pekk post with diameter = 0.70 mm, group 2 received pekk post with diameter = 0.90 mm, group 3 received pekk post with diameter = 1.10 mm, group 4 received pekk post with diameter = 1.50 mm, and group 5 received pekk post with diameter = 1.70 mm. All the posts were cemented using a self-adhesive resin cement. Fracture resistance was tested using a universal testing machine, failure patterns were then observed visually and radiographically. For the fracture resistance test, the Universal Testing machine employed the load cell of 10KN and the speed of the cross head of 1mm/min. Data was analyzed using Oneway analysis of variance (ANOVA) followed by Tukey post-hoc test in order to determine significant differences among groups and the materiality threshold was set at α = 0.05. Results: Statistical analysis revealed that the observed differences among the five groups were not significant. None of the PEKK posts caused any fracture in the root, and this observation was visually and radiographically confirmed across all groups. Conclusions: The dentist will be able to turn the diameter of the PEKK post and core as thin as 0.70mm till 1.70mm depending on the clinical requirement with no risk of root fracture, as specified by the guidelines of this research.

Influence of Endodontic Cavity Design on Interfacial Voids, Class II Resin Composites Sealing Ability and Tooth Fracture Resistance: An In Vitro Study.

Objective: The aim of this in vitro investigation is to study the effect of endodontic cavity design on interfacial voids, class II resin composite sealing ability, and fracture resistance in mandibular premolars. Methods: A total of 48 single-rooted mandibular premolars received compound class II preparations with either traditional flare access cavities (group A) or contracted endodontic cavity preparations (group B). Each study group was subdivided according to the coronal restoration into two sub-groups as α and β. In the α group, a microhybrid composite was used after etch-and-rinse bonding technique using an MDP-containing universal adhesive. In the β group, a self-adhesive composite was used as coronal restoration after endodontic treatment (n = 12) for each subgroup. A micro-CT analysis was performed to assess the obturation interfacial voids and tracing of class II cervical interfacial adaptation. The tooth fracture resistance testing was then performed adding an extra group of 12 sound non-prepared teeth, which were tested as the control for fracture strength testing. A one-way ANOVA and post-hoc testing were used together with descriptive statistics for an analysis of the mean values of obturation interfacial voids. A two-way ANOVA was used to assess the fracture resistance test results, and to find the influence of endodontic access design and the type of composite material on the fracture resistance testing. Chi-square testing was employed to analyze the cervical interfacial seal of the class II restorations. Results: A one-way ANOVA revealed that there were no statistically significant differences between test groups in the amount of obturation interfacial voids (p > 0.05). There were no statistically significant differences between test groups in terms of cervical interfacial sealing ability (p > 0.05). A two-way ANOVA revealed that no statistically significant differences between test groups including the control group existed in terms of the fracture resistance testing (p > 0.05). Conclusions: Although it does not improve tooth fracture resistance, the contracted endodontic access cavity does not deteriorate the quality of obturation in terms of the interfacial porosity. The self-adhesive composite does not improve the efficiency of cervical interfacial adaptation or tooth fracture resistance regardless of the endodontic access cavity shape, yet it revealed a substantial load-bearing capacity.

In-vitro comparison of fracture resistance of CAD/CAM porcelain restorations for endodontically treated molars

BackgroundThis study evaluates the fracture strength and patterns of feldspathic porcelain restorations made using CAD/CAM technology for lower first molars with extensive crown destruction. The restorations include post-core and full-contour crown, composite resin core and full-contour crown, and endocrown. This research provides insights into effective restorative options to address tooth fracture risk, supporting minimally invasive procedures and CAD/CAM integration in dental practices.MethodsThis study utilized 80 permanent mandibular first molars, which were divided into four groups: Group I (Post-Core-Full-contour crown), Group II (Core- Full-contour crown), Group III (Endocrown), and Group IV (Control). Root canal treatment was performed on all samples except for the control group. Following access cavity preparation, restorations for each tooth were fabricated using the CAD/CAM system and cemented with resin cement. The specimens were embedded in acrylic blocks. After undergoing thermomechanical aging, the samples were subjected to fracture resistance testing using a universal testing machine, which applied force until fracture occurred. The fracture patterns were subsequently analyzed, and the data were statistically evaluated using the Kruskal-Wallis and Chi-Square tests (p < 0.05).ResultsA significant difference in fracture values under axial forces was observed (p < 0.05). The control group had the highest fracture strength (1830 ± 277 N), while the Core- full-contour crown group showed the lowest (1532 ± 371 N). Failure types varied significantly among the groups (χ2 = 26.886, df = 9, p = 0.001). The most common failure type was Type-2 (33.75%), characterized by restorable fractures, while Type-3 fractures, unrestorable, were the least common (12.5%).ConclusionsThe findings underscore the significance of technological advancements in CAD/CAM for effectively restoring endodontically treated teeth with extensive crown damage. This study contributes valuable insights, emphasizing the clinical relevance of selecting appropriate restorative options to mitigate the risk of tooth fracture associated with coronal restoration failures.

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

Effects of minimally invasive endodontic access cavity in molar teeth on polymerization, porosity and fracture resistance

Minimally invasive access cavities have been proposed in the last decade to reduce tooth tissue loss during endodontic treatment and mitigate compromised fracture resistance of endodontically treated teeth. Fracture resistance of molars with different types of access cavity design may be affected by restorative materials and aging. Insufficient literature data exist on the effect of cavity design and type of restorative materials on restorative aspects such as material adaptation or photo-polymerization in restricted access cavities. This study analyses quality of polymerization, material adaptation and fracture resistance of molars with different types of access cavities restored with glass-ionomer, high-viscosity fiber-reinforced bulk-fill and nanofilled resin composite. Plastic molar teeth with truss (TREC) and traditional endodontic access cavity (TEC) were restored with nanofilled composite (Filtek Supreme), glass-ionomer Fuji IX and Filtek or fiber-reinforced everX Posterior and Filtek. Porosity was determined using microcomputer tomography and the degree of conversion of resin-based materals using micro-Raman spectroscopy. Human molars prepared and restored in the same way were used for fracture resistance testing at baseline and after thermocycling. The results demonstrate that high-viscosity fiber-reinforced composite was difficult to adapt in TREC cavity leading to greater porosity than Filtek or Fuji. TREC design did not affect composite polymerization and led to higher fracture resistance of restored molars compared to TEC but also more unrestorable fractures.

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.

Evaluation of fracture resistance and marginal fit of implant-supported interim crowns fabricated by conventional, additive and subtractive methods

BackgroundInterim crowns are utilized for restoring implants during and after the process of osseointegration. However, studies on adaptation and fracture strength of implant-supported interim crowns are rare.Aim of the studyThe aim of this in vitro study is evaluating marginal fit and fracture resistance of conventional, subtractive, and additive methods of fabricating implant-supported interim crowns.Materials and methodsAn implant was placed in an epoxy resin model with a missing first molar. A scan body was attached, and scanned with an intraoral scanner (IOS), the STL file was used to fabricate eighteen master models with standardized implant digital analogue spaces. The digital analogues and their corresponding abutments were attached to the master models and scanned with the IOS, the STL files were used to fabricate eighteen crowns using three different techniques (n = 6): conventional (CR); from Autopolymerizing composite resin, subtractive (SM); milled from PMMA resin blanks, and additive (AM); from 3D printed resin material. The crowns were fitted and cemented on their corresponding abutments and subjected to cyclic loading and thermocycling. The marginal fit was evaluated using a stereomicroscope. The crowns were then loaded until fractured in a universal testing machine. The Shapiro–Wilk and the Kolmogorov-Smirnov tests revealed that data of Marginal gap was non-parametric. Kruskal-Wallis test followed by the Dunn test was used (α = 0.05). While data of Fracture resistance test was parametric. ANOVA (F-test) was used followed by the Tukey test (α = 0.05).ResultsFor marginal gap, a significant difference was shown between the study groups (P = .001) according to Kruskal–Wallis test. Groups SM and AM had significantly lower marginal gap values compared to group CR (P = .003). No significant difference was found between groups SM and AM (P = .994). For fracture resistance, One-way ANOVA revealed a significant difference in fracture resistance between study groups (P < .001). Group SM had significantly higher fracture strength followed by group AM and group CR (P = .001).ConclusionsGroup SM and AM showed better marginal adaptation than group CR. Group SM showed superior fracture resistance compared to other groups. All study groups showed acceptable marginal gap and fracture resistance.

Exploring access cavity through non-carious cervical lesions: Impacts on instrumentation, obturation, and fracture resistance in mandibular incisors.

To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors. Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student's t-test, with a statistical significance level of 5%. Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008). CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.

The effect of thermomechanical aging on the fracture resistance of additively and subtractively manufactured polyetheretherketone abutments

ObjectivesTo evaluate the fracture resistance (FR) of polyetheretherketone (PEEK) abutments produced by additive and subtractive methods compared to milled zirconia abutments. MethodsCustom abutments were designed on Ti-base abutments and produced from three different materials, namely additively manufactured PEEK (PEEK-AM), subtractively manufactured PEEK (PEEK-SM), and zirconia (N = 60). PEEK-AM abutments were printed using PEEK filaments (VESTAKEEP®i4 3DF-T, Evonik Industries AG) on a M150 Medical 3D Printer (ORION AM) by fused filament fabrication (FFF). All surface treatments were carried out according to the manufacturer's instructions. All abutments were cemented on Ti-bases with hybrid abutment cement and then restored with milled zirconia crowns. Each subgroup was divided into non-aged and aged subgroups (n = 10). The aged groups were subjected to thermomechanical aging (49 N, 5–55 °C, 1.2 million cycles). FR tests were performed by using an universal testing machine. Data were statistically analyzed with one-way and two-way ANOVA and t-test. ResultsThe survival rate of the specimens after aging was determined as 100%. It was found that both the material and aging had a significant effect on the FR (p<.001). There was a statistical difference among the fracture values of the groups (p<.001). In both the aged and non-aged groups, PEEK-AM showed the statistically lowest FR, while the highest FR was seen in the zirconia group, which was significantly higher than the PEEK-SM (p<.001). ConclusionHybrid abutments were successfully manufactured, and extrusion-based processed PEEK seems to be a good alternative to subtractive processed PEEK. However, since subtractive manufacturing still appears to be superior, further developments in additive manufacturing are needed to further improve the quality of 3D-printed PEEK parts, especially in terms of accuracy and bonding between adjacent layers. Clinical SignificanceAdditively manufactured PEEK abutments have the potential to be an alternative for implant-supported restorations in the posterior region.

Applications of Finite Element Analysis in Endodontics: A Systematic Review and Meta-Analysis

ABSTRACT Background: Endodontics increasingly uses finite element analysis (FEA) to evaluate stress distribution, fracture resistance, and temperature changes in treated teeth. FEA’s endodontic uses, benefits, and drawbacks are examined in this systematic review and meta-analysis. Methods: A PubMed systematic search found relevant studies published up to January 2022. Original endodontic research articles utilizing FEA to quantify stress distribution, fracture resistance, or temperature changes in treated teeth were eligible. The systematic review comprised 30 publications, 15 of which were meta-analyzed. Data were extracted using a standard form, and the “Newcastle-Ottawa Scale (NOS)” for observational studies and the Cochrane risk of bias tool for randomized controlled trials assessed quality. Random-effects models calculated pooled effect sizes and 95% confidence intervals in RevMan 5.4 meta-analysis. Results: Meta-analysis shows FEA-guided endodontic treatment improves stress distribution (P &lt; 0.001) and fracture resistance (P &lt; 0.05) compared to conventional treatments. The temperature did not vary significantly (P = 0.12). Stress distribution had an effect size of 0.75 (95% CI: 0.65–0.85), fracture resistance 0.42 (95%: 0.12–0.72), and temperature variations -0.18. Conclusion: In conclusion, FEA is a valuable technique in endodontics for stress distribution study and fracture resistance testing. FEA models’ accuracy, dependability, and clinical applicability were questioned, underlining the need for more research and development to maximize their endodontics clinical use.

Fracture resistance of endodontically treated root obturated with different root canal sealers( A comparative in vitro study)

Aim: The aim of this study is to evaluate and compare the fracture resistance of endodontically treated root obturated with four different root canal sealers.. Methods: Sixty extracted palatal root of upper molars were collected and sectioned to get a 11mm root length. All root canals were instrumented using edge endo X7 system rotary files and 35# size was the final size used to finish all the canals. After instrumentation the samples were divided into four groups of 15 samples in each according to the type of sealer used, a single cone obturation technique was used: Group 1: obturated with AH Plus sealer and gutta-percha. Group 2: obturated with Neosealer BC sealer and gutta-percha. Group 3: Obturated with MTA-Fillapex sealer and gutta-percha. Group 4: Obturated with OneFill BC sealer and gutta-percha. After incubation period of 7 days at 37°C and 100% humidity the samples covered with thin layer polyvinylsiloxane impression material to simulate a periodontal membrane and then molded in acrylic blocks so as to set the samples ready for fracture resistance test using universal testing machine at a cross head speed of 0.5mm/min., One-way ANOVA and Posthoc tests assessed the data statistically. Results: The results showed that fracture resistance was significantly higher in those canals that were filled with Neosealer BC sealer (69.90N) in comparison to the other different sealers used in the study (p≤0.05). Conclusion: Under the condition of this study, the following conclusions can be derived: The application of any root canal sealers resulted in an enhancement of the resistance to fractures in teeth that have undergone endodontic treatment. Neosealer Bioceramic sealer group showed the highest fracture resistance than other groups. Followed by Onefill bioceramic, MTA Fillapex and Ah plus.

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.

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.

Fracture resistance and failure mode of three esthetic CAD-CAM post and core restorations

BackgroundThe rising demand for improved aesthetics has driven the utilization of recently introduced aesthetic materials for creating custom post and core restorations. However, information regarding the fracture resistance of these materials remains unclear, which limits their practical use as custom post and core restorations in clinical applications.Aim of the studyThis study aimed to evaluate the fracture resistance of three non-metallic esthetic post and core restorations and their modes of failure.Materials and methodsThirty-nine single-rooted human maxillary central incisors were endodontically treated. A standardized post space preparation of 9mm length was performed to all teeth to receive custom-made post and core restorations. The prepared teeth were randomly allocated to receive a post and core restoration made of one of the following materials (n=13): glass fiber-reinforced composite (FRC), polyetheretherketone (PEEK) and polymer-infiltrated ceramic-network (PICN). An intraoral scanner was used to scan all teeth including the post spaces. Computer-aided design and computer-aided manufacturing (CAD-CAM) was used to fabricate post and core restorations. Post and core restorations were cemented using self-adhesive resin cement. All specimens were subjected to fracture resistance testing using a universal testing machine. Failure mode analysis was assessed using a stereomicroscope and SEM. The data was statistically analyzed using One-Way ANOVA test followed by multiple pairwise comparisons using Bonferroni adjusted significance level.ResultsCustom PEEK post and core restorations displayed the least fracture load values at 286.16 ± 67.09 N. In contrast, FRC exhibited the highest average fracture load at 452.60 ± 105.90 N, closely followed by PICN at 426.76 ± 77.99 N. In terms of failure modes, 46.2% of specimens with PICN were deemed non-restorable, while for PEEK and FRC, these percentages were 58.8% and 61.5%, respectively.ConclusionsWithin the limitation of this study, both FRC and PICN demonstrated good performance regarding fracture resistance, surpassing that of PEEK.

Fracture Resistance and Push-Out Bond Strength of Three Post Types in the Restoration of Anterior Primary Teeth - A In Vitro study.

Restoration fractures and displacement are the two main causes of failure after the rehabilitation of severely worn primary anterior teeth. Compare the effect of three post types on the fracture and push-out bond strength. Sixty undamaged maxillary anterior primary teeth were allocated into three groups according to post type: (I) Tetric N Ceram composite post, (II) prefabricated glass fiber post, and (III) high viscous glass ionomer post. Each group was further subdivided into two sub-groups depending on the test used: fracture resistance test and push-out bond strength test. The all specimens were mounted in acrylic resin blocks and tested using a universal testing machine. The fracture and failure mode were determined by a stereomicroscope inspection of all the specimens. Data were analyzed by one-way analysis of variance (ANOVA) and the Bonferroni post hoc test ( P < 0.05). There was a statistically significant difference between fracture resistance and push-out bond strength values for the experimental groups ( P < 0.05). The most significant fracture resistance value was in Group II and core/post fracture (restorable fracture) was the most obvious fracture in the three groups with the highest percentage in Group I. The most significant push-out bond strength value was in Group I and adhesive failure between dentin and luting cement/post was the most common type in the groups. The fracture resistance and push-out bond strength were affected by the type of post ( P = 0.000). Prefabricated glass fiber posts showed the highest fracture resistance in this study. However, Tetric N Ceram composite posts had the most restorable fracture. Tetric N Ceram composite posts had the highest bond strength with adhesive failure mode.

Effectiveness of Chitosan Oligosaccharide as Chelating agent in Smear Layer Removal and The effect on Fracture Resistance of Endodontically Treated Teeth

One factor affecting root canal treatment's success is the cleanliness of root canal systems. Smear layer removal is needed to ensure the cleanliness of root canals. Fracture resistance is also essential things in endodontic-treated teeth. Chitosan is one of the irrigant alternatives in dentistry that is biocompatible. The study aimed to investigate the effect of chitosan oligosaccharide as a root canal chelating alternative in the cleaning smear layer and its impact on fracture resistance of endodontic treated teeth.Experimental research with 56 mandibular premolar teeth with a single canal was used. For the smear layer cleanliness test, 24 teeth were used and divided into four treatment groups. Statistical analysis used was the one‑way analysis of variance and LSD Post Hoc test. Thirty-two teeth were divided into two treatment groups for the fracture resistance test. The statistical analysis used was the Independent T-test. There was no significant difference between smear layer removal in chitosan oligosaccharide 2% and EDTA 17% groups. There was a considerable difference between fracture resistance of endodontic treated teeth in chitosan oligosaccharide 2% and EDTA 17% groups. Chitosan oligosaccharide 2% can be used as an alternative in the final irrigation of root canal treatment.

Evaluation of mechanical properties of anatomically customized fiber posts using E-glass short fiber-reinforced composite to restore weakened endodontically treated premolars

ObjectiveThis study was conducted to assess the influence of combining different forms of fiber-reinforced composites (FRC) on the mechanical behavior and bond strength of compromised endodontically treated teeth (ETT).Materials and methodsEighty extracted human premolar teeth were randomly divided into five experimental groups according to the type of intra-radicular restoration and the canal preparation design which was either non-flared (Group 1), flared (Groups 2–5), closed-apex (Groups 1,3,5) or open-apex (Groups 2,4). Standard prefabricated fiber posts were used as intra-radicular restoration for Groups 1–3 while Groups 4–5 were restored with anatomically customized relined fiber posts. After composite core fabrication, all samples were sent for an artificial aging process. Fracture resistance and push-out bond strength tests were then carried out through a universal testing machine followed by mode of failure analysis via a stereomicroscope and scanning electron microscope.ResultsPairwise Log-Rank comparisons revealed that the survival rate of Group 2 and Group 3 was significantly lower than all other groups after artificial aging. The highest fracture resistance value (1796 N) was recorded in Group 5 and was significantly higher than that of the other groups (p < 0.05), while Group 2 exhibited the lowest fracture resistance (758 N), which was significantly lower compared to the other groups. Group 5 and Group 4 demonstrated a significantly higher push-out bond strength, at all root thirds, than Group 3, Group 2, and Group 1 (p < 0.05). The most frequently observed failure mode in the tested groups occurred between the resin cement and radicular dentin.ConclusionThe use of short fiber-reinforced composite (SFRC) to reline the prefabricated FRC post has been proven to have superior fracture resistance with favorable failure patterns and increased push-out bond strength values compared to standard prefabricated FRC posts.

Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study.

To investigate six different strengthening mechanisms for three-unit implant-supported provisional restorations. Six techniques of provisional fixed prostheses (PFP) reinforcement were investigated and were assigned to different groups (n = 10): group (ZP) zirconia powder, group (SK8) silk thread wrapped as a figure-of-8 pattern around middle third of abutment, group (RC8) size 00 retraction cord wrapped as a figure-of-8 pattern around middle third of abutment, group (RF8) Resin impregnated glass fiber ribbon wrapped as a figure-of-8 pattern around abutment, group (KV8) Kevlar 29 cord wrapped as a figure-of-8 pattern around middle third of abutment, group (KV) Kevlar 29 strands incorporated in resin mix. Compared against unenforced bis-acryl as control group (CL). Seventy Metal Dies were 3D printed having Soft Tissue Gingiva Mask. Using a custom-made silicone Index, 70 PFP were fabricated (10 of each group) and were cemented to their corresponding metal dies using zinc polycarboxylate cement. All specimens were thermal cycled for 1000 cycles using order of 20 seconds at 55°C and 20 seconds at 5°C with 10 seconds transport. Fracture resistance test was done using universal testing machine. All specimens were loaded to failure. Data were collected, tabulated and statistically analyzed. Kolmogorov-Smirnov normality test showed no significant difference between data in each group. So, data are normally distributed in each group. Descriptive statistics showed higher mean values of CL group (780.8 ± 164) followed by RF8 group (614.2 ± 158.2), followed by RC8 group (550.2 ± 339.2), followed by KV8 group (442.1 ± 198.4), followed by KV group (403.9 ± 306), followed by SK8 group (175.9 ± 90.8), and finally ZP group (136.5 ± 135.7). One-way ANOVA revealed significant difference between the tested groups (p = 0.036). Bis-acryl provisional restorations had better mean fracture resistance values than all other strengthening mechanisms. Bis-acryl provisional restorations did not gain more strength by any of the added materials. One-way ANOVA revealed significant difference between all tested groups. Provisional restorations over implant should be strong enough to serve for the long period of bone and tissue healing. Current materials alone cannot survive for long. It serves as temporization between steps of fixed restorations construction. How to cite this article: Rayyan M, Sayed M, Hujeiry AM et al. Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study. J Contemp Dent Pract 2023;24(11):840-846.

Effect of Clinical Sandblasting on the Surface Roughness of Zirconia Cores for all Ceramic Crowns and their Fracture Resistance after the Addition of Repair.

Objective: This in vitro study aims to evaluate the effect of clinical sandblasting with 50 μm aluminum oxide and 30 μm silica-coated particles on the surface roughness of zirconia cores and the subsequent effect on their fracture resistance after veneering with composite using a specific repair kit. Materials and Methods: Zirconia cores (n=21) were digitally designed and milled from ZirCAD LT B1 (IPS e.max ZirCAD ) blocks using arum 5x-300 Pro (ARUM DENTISTRY). These cores were randomly divided into three groups: Group A: n=8, sandblasted with 50 μm aluminum oxide, and veneered with packable Z350 composite. Group B: n=8, sandblasted with 30 μm silicacoated particles and veneered with packable Z350 composite. Group C: control group (n=5), sandblasted in the laboratory with 110 μm aluminum oxide and veneered with porcelain (Vintage Zr PRO - SHOFU Dental GmbH). All the specimens were tested for surface roughness by the TAYLOR-HOBSON profilometer. After adding veneering material, all the specimens were subjected to a fracture resistance test through a universal testing machine. Results: One-way ANOVA test showed a significantly higher surface roughness in group B compared to group A. Fracture resistance values showed no significant difference between all the groups. Conclusion: Silica-coated particles produced higher surface roughness than aluminum oxide alone. The fracture resistance values of all the groups were above the acceptable clinical limit. Keywords: Aluminum-oxide, Intra-oral repair, Sandblasting, Silica, Surface Roughness, Zirconia