Mean Fracture Resistance Research Articles

Thickness and yttria percentage influencesthe fracture resistance of laminate veneer zirconia restorations.

Mechanical properties are cardinal for the long-term clinical success of laminate veneer restorations but the selection of new restorative materials should ideally be based on clinical evidence, therefore, in vitro testing of dental materials is a good alternative to evaluate their properties and understand their behavior so this study aimed to compare and evaluate the effect of two different thicknesses and yttria percentage on the fracture resistance of laminate veneer zirconia restorations. Fortylaminate veneer restoration prepared from partial sintering zirconia of 3Y (yttria), 5Y (yttria), combined 3Y&5Y (yttria), and lithium disilicate. Specimens were assigned into four main groups according to their percentage of yttria content (n = 10) and subgrouped into two thicknesses (0.5 mm thickness and 0.3 mm thickness) (n = 5) as follows: Group I, II, III,and IV (Group I for lithium disilicate (control), Group II for 3Y zirconia, Group III for 5Y zirconia, and Group IV for combined 3Y&5Y zirconia), each of them subdivided according to their thickness into two subgroups (n = 5 for each one) and resistance to fracture for each restoration was evaluated using a universal testing machine. Data were analyzed using aone-wayanalysis of varianceand Duncan's tests at a 5% level of significance. The thickness of laminate veneer restoration significantly affects the fracture resistance value of all type of laminate veneers restorations (fracture resistance mean value was highest for 0.5 mm thickness and lower for 0.3 mm thickness restorations) and yttria percentage significantly affect fracture resistance value of zirconia laminate veneer restorations (fracture resistance mean value was highest for 0.5 mm thickness of 3Y zirconia [865 N] and combined 3Y&5Y zirconia [846 N]). Reducing the thickness of laminate zirconia veneer restorations to 0.3 mm reduces its fracture resistance and increasing yttria percentage had an adverse effect on fracture resistance of zirconia laminate veneer restorations.

Marginal and internal fit and fracture resistance of three-unit provisional restorations fabricated by additive, subtractive, and conventional methods.

To compare the marginal and internal fit and fracture resistance of three-unit provisional fixed dental prostheses (FDPs) fabricated by additive, subtractive, and conventional methods. Eighty 3-unit FDPs were fabricated on metal dies of the maxillary right second premolar and second molar by four different techniques (n = 20): The direct method by using autopolymerizing polymethyl methacrylate (PMMA), indirect method by the compression molding technique, subtractive manufacturing by using PMMA blocks, and additive manufacturing by using digital light processing technology. The adaptation of restorations at the marginal, axial, cuspal, and fossa areas was assessed by using the silicone replica technique. After thermocycling and cyclic loading, the fracture resistance was measured by a universal testing machine. Data were analyzed by atwo-wayanalysis of variance (ANOVA), ANOVA, and Tukey test (α = .05). The mean gap measured in the additive group was lower than that in all other groups at all points (p < .05); however, the difference in the marginal gap with the subtractive group was not significant (p = .995). The mean marginal and axial gaps in the subtractive group were significantly lower than the corresponding values in both conventional groups (p < .05). A significant difference existed between all groups regarding the mean cuspal and fossa gaps (p < .05). The mean fracture resistance of the additive group was significantly higher than that of indirect (p = .018) and direct (p < .001) groups, and the fracture resistance of the subtractive group was significantly higher than that of the direct group (p = .020). The digitally fabricated provisional FDPs showed superior marginal and internal fit and higher fracture resistance than the conventionally fabricated FDPs. Between the digital methods, the additive technique yielded superior internal fit.

Fracture Resistance of Custom Lithium Disilicate Implant Restorations with Two Fabrication Techniques and Two Designs.

To compare the fracture resistance of a press-on ceramic custom implant restoration with pressed and cemented restorations. Thirty-two (32) lithium disilicate (IPS e.max Press) custom hybrid abutment restorations were fabricated. The restorations were divided into two groups (n = 16) according to the construction technique: the commercial control group (C) and the press-on group (P). For the control group, lithium disilicate restorations were pressed and cemented on titanium bases. For the press-on group, lithium disilicate pressable ceramic (IPS e.max Press) was pressed on the titanium bases with injection molding. Each group was further divided according to the restoration design, either screw- or cement-retained, into two subgroups of eight specimens each. Specimens of C group were divided into screw-retained (cemented hybrid abutment crown, CHAC) or cement-retained (cemented hybrid abutment, CHA). Specimens of the P group were also divided into screw-retained (pressed hybrid abutment crown, PHAC) and cement-retained (pressed hybrid abutment, PHA). The specimens were subjected to static loading until failure with a universal testing machine. Two-way analysis of variance (ANOVA) was used to assess the effect of different techniques and designs on the fracture resistance of the samples (P < .05), followed by one-way ANOVA and Tukey honest significant difference (HSD) test (α = .05). C group showed higher mean fracture resistance (812.443 ± 129.14 N) than P group (596.71 ± 108.83 N), and the difference was statistically significant (P < .05). Regarding restoration design, HA groups showed higher mean fracture resistance (742.621 ± 153.82 N) than HAC (666.53 ± 163.07 N) groups with no statistically significant difference. CHA showed the highest mean fracture resistance (817.65 ± 161.76 N), while PHAC showed the lowest mean fracture resistance values (525.83 ± 47.29 N). The commercial cemented lithium disilicate restorations showed higher fracture resistance than the press-on restorations, although both showed a maximum load capacity that was greater than physiologic incisal force in the anterior region, and both hybrid abutments and hybrid abutment crowns were equally efficient in withstanding occlusal loading forces.

The Influence of Ferrule on the Marginal Gap and Fracture Resistance of Zirconia Endocrowns.

To investigate the precementation mean marginal gap, fracture resistance, and mode of failure of monolithic zirconia endocrowns cemented to endodontically treated molar teeth with butt joint porcelain margins and added ferrule preparation designs. A total of 20 mandibular molars were endodontically treated and prepared to receive endocrown restorations. The teeth were randomly divided into two groups: Group B had a butt joint porcelain margin, while Group F received additional axial reduction with a shoulder finish line that added ferrule. Monolithic zirconia endocrowns were milled, and the marginal gaps were measured at four locations prior to cementation with resin cement. All samples were subjected to thermocycling, followed by compressive static loading. The maximum load causing fracture and mode of failure were recorded. The mean load to failure for Group B (5,616 ± 1,503 N) was not significantly different compared to Group F (5,762 ± 1,618 N) (P = .84). Both groups recorded high rates of irreparable fractures (P = .2699, df = 2). The mean marginal gap in Group B (48.20 ± 12.37 μm) was not statistically significantly different compared to Group F (45.14 ± 8.45 μm) (P = .527). The addition of ferrule to the preparation design had no significant effect on the precementation mean marginal gap, fracture resistance, or mode of failure of monolithic zirconia endocrowns cemented to endodontically treated molar teeth. Monolithic zirconia endocrowns failed predominantly in an irreparable manner, but these failures were at high failure loads. The precementation mean marginal gap for both groups was small in comparison to other materials.

Zirconia Cantilever Fixed Dental Prostheses Supported by One or Two Implants: An In Vitro Study on Mechanical Stability and Technical Outcomes

To evaluate the mechanical stability of highly translucent zirconia (Zr) cantilevered fixed dental prostheses (cFDPs) and to investigate the influence of the number of implants (one versus two) supporting cFDPs with different restorative materials on their mechanical stability and load-bearing capacity. Thirty-two specimens consisting of implant-supported prostheses embedded in resin blocks were fabricated. Sixteen specimens received one implant (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) to support two-unit cement-retained cFDPs with one extension unit and the other 16 received two implants (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) positioned corresponding to the missing maxillary central incisors to support three-unit cement-retained cFDPs with one extension unit. Two different prosthetic materials, chromium-cobalt (Cr-Co; Wirobond C+, Bego) and highly translucent Zr (Lava Plus, 3M ESPE) were selected to fabricate the two- and three-unit cFDPs. Standardized twoand three-unit Cr-Co frameworks (CC-I, n = 8; CC-II, n = 8) and highly translucent Zr frameworks (Zr-I, n = 8; Zr-II, n = 8) with a 6-mm cantilever extension were fabricated using CAD/CAM (EOS M 290). Following thermomechanical fatigue loading, the specimens were tested for fracture resistance under static loading. The influence of restoration material and number of supporting implants on fracture resistance were tested using two-way analysis of variance (ANOVA). The level of statistical significance was set below 5% (α < .05). All specimens survived aging. The mean (± standard deviation) fracture resistance values were 416.25 (± 42.71) N for Zr-I, 548.75 (± 75.41) N for Zr-II, 601.0 (± 41.51) N for CC-I, and 664.5 (± 37.59) N for CC-II. CC and Zr group specimens showed significantly different fracture resistance results (P < .001). The number of implants significantly influenced the fracture resistance of Zr groups (P = .001), whereas the influence was not significant for CC groups (P = .089). Within the limitations of this in vitro study, highly translucent zirconia cFDP frameworks demonstrated the potential to withstand reported physiologic occlusal forces applied in the anterior region. The increase in the number of implants supporting zirconia cFDPs significantly contributed to achieving higher fracture resistance values.

Comparative evaluation of the fracture resistance of three different recent composite systems in large class II MOD cavities

Background: For severely mutilated teeth, this research evaluated the most contemporary restorative material. Aim: Repair of Class II MOD cavities in premolars with Ever X posterior in the recent past, Beautifil restorative, and the Universal TetricEevoCream composite systems will be evaluated and compared in this research. “Materials and Methods:” Sixty human maxillary premolars were chosen for the study. As a check, we utilised a group of fifteen healthy teeth (Group 1). The remaining 45 teeth were fitted with MOD cavities of standardised dimensions and randomly assigned to one of three groups (Groups 2, 3, and 4) (n = 15). They used Beautifil restoratives for teeth in Group 2, GC Ever X posterior for teeth in Group 3, Universal Tetric EvoCream for teeth in Group 4. Newtons were used to measure the strength of a material (N). Results: Group 4 exhibited the greatest mean fracture resistance of the four groups, followed by Groups 3, 1, and 2 and finally Group 4. Conclusion: It was found that the Universal Tetric EvoCream composite had the greatest fracture resistance among the test groups. There was a substantial statistical difference between all of the groups.&#x0D;

The Effect of Chloroquick on Fracture Resistance of Root Filled Teeth- An In-Vitro Study

Aim: To evaluate and compare the fracture resistance of endodontically treated teeth irrigated with different irrigating solutions under instron testing machine. Materials and Methodology: Hundred extracted, human, single rooted mandibular premolars, recently extracted from patients for orthodontic purpose were selected. All the teeth were decoronated upto a standardised length of 12 mm. All the teeth were then biomechanically prepared upto size F4 and chemomechanically irrigated with different combinations of irrigants : Group 1: Chloroquick, Group 2: 5% EDTA(ethylenediamine tetra acetic acid) and 2.5% NaOCl(so, Group 3: 17% EDTA and 2.5% NaOCl, Group 4: 5% EDTA, Chloroquick and 2% Chlorhexidine and Group 5: 17% EDTA, Chloroquick and 2% Chlorhexidine followed by insertion of F4 gutta percha cones and application of AH Plus 26 sealer. All teeth irrespective of the groups were stored at 370C and 100% relative humidity for 14 days to allow sealer to set and each group was subjected to instron testing machine to evaluate their fracture resistance. The force required to fracture each specimen was recorded in Newtons and data were analysed statistically using analysis of variance ( ANOVA) test and Post- Hoc Tukey test. Results: The mean fracture resistance of Group 5 was highest followed by Group 3, Group 1, Group 4 and Group 2. (Group 2&lt;Group 4&lt;Group 1&lt;Group 3&lt;Group 5). The mean fracture resistance of Group 5 was significantly higher than rest of the groups (P&lt;0.001) and also of Group 3 was significantly higher than other groups. Conclusion: In context to all the irrigating solutions used for chemomehanical preparation, Chloroquick and it’s combination with 17% EDTA and 2% Chlorhexidine showed higher fracture resistance.

Comparative evaluation of the fracture resistance of newly developed prefabricated fibreglass crowns and zirconium crowns.

Prefabricated fibreglass crowns (PFCs) require less tooth structure reduction than prefabricated zirconium crowns (PZCs) for restoring primary molars. Little is known, however, about their mechanical properties. To investigate the fatigue survival and fracture resistance of PZCs and PFCs cemented with two different types of luting cement [glass-ionomer cement (GIC) and resin-modified GIC (RMGIC)]. One hundred and twenty extracted human primary molars were randomly divided into subgroups (n=15) according to the crown type (PFCs/PZCs), the luting cement (GIC/RMGIC) and crowns subjected to the chewing simulation test with thermocycling mechanical loading (CSTTML). The surfaces of the teeth were reduced by approximately 2mm in the PZC group and 1mm in the PFC group. All the samples were subjected to fracture tests. None of the samples subjected to CSTTML exhibited signs of surface damage, fracture or premature debonding. The forces required to fracture PFCs were higher than those required for PZCs in all groups (p=.001). The highest mean fracture resistance values were obtained from the group of PFCs cemented with GIC that were subjected to the CSTTML (2515.8N±619.2N). PFCs presented high fatigue survival and could be used as alternatives to PZCs as they require less tooth structure reduction. Crowns cemented with GIC had a similar fracture resistance value when compared with RMGIC.

Comparing the Fracture Resistance and Modes of Failure in Different Types of CAD/CAM Zirconia Abutments with Internal Hexagonal Implants: An In Vitro Study.

Three groups of zirconia abutments (n = 5) consisting of different connection designs or manufacturers were investigated (All-Zr, ASC-Zr, and AM-Zr groups). All-electric dynamic test instruments were used to place static loading on a specimen with a crosshead speed set at 1 mm/min. A Kruskal–Wallis test and a post hoc Mann–Whitney U test were used for statistical evaluation. The mean fracture resistance was 252.37 ± 82.79 N for the All-Zr group, 384.62 ± 45.24 N for ASC-Zr group, and 361.83 ± 90.31 N for the AM-Zr group. The difference of fracture resistance between the three groups was marginally significant (Kruskal–Wallis test, p = 0.054), with the ASC zirconia abutment tending to have higher fracture resistance than the full zirconia abutment. The modes of failure among the three types of abutments are different. The All-Zr group showed an oblique fracture line starting from the buccal aspect at the region of the implant platform. While the ASC-Zr and AM-Zr groups showed a relatively horizontal fracture line with a greater distance from the implant platform. The titanium inserts cannot significantly improve the fracture resistance of the zirconia abutment. However, they may alter the modes of failure, allowing buccal fracture surfaces of the zirconia abutments to be placed away from the implant platform, thereby protecting the implant–abutment connection.

Fracture resistance to treated teeth using known endodontics techniques in Indian patients.

Teeth with crown structure less than 50% can be restored. Therefore, it is of interest to evaluate an in vitro efficacy of Zirconia post, Glass fiber post, polyethylene-woven fiber posts, and Quartz posts. Forty eight recently extracted mandibular first premolar teeth were randomly grouped in to 4 different groups with 12 samples in each group. After endodontic treatment samples in all groups underwent post preparation followed by restoration with respective posts. The mean fracture resistance (Newton) were 463.5 ± 14.3 (Group I) 425.2± 23.5 (group II), 410.4± 18.6 (Group 3) and 385.2 ± 14.2 (group 4). Data shows that Zirconia post had highest fracture resistance compared to other tested groups.

Evaluation of fracture resistance of FRC posts, zirconia post and Parapost in endodontically-treated teeth

Objectives: To evaluate the fracture resistance efficacy of FRC posts and photo core, zirconia post and Parapost in endodontically treated teeth. Materials and Method: Thirty recently extracted mandibular first premolar teeth were randomly grouped in to 3 different groups with 10 samples in each group: FRC posts and photo core, zirconia post and Parapost. Fracture resistance in each group was estimated and compared. Results: The fracture resistance was 428.2, 432.1 and 232.5 for group I, II and III. The difference was statistically significant. The mean fracture resistance between group I to Group III and II with III was statistically significant (0.01). The fracture resistance between Group I and II was not significant (P&gt;0.65). Conclusion: Authors found that zirconia and FRC posts exhibited higher fracture resistance as compared to paraposts.

Survivability and fracture resistance of monolithic and multi-yttria-layered zirconia crowns as a function of yttria content: A mastication simulation study.

To compare four different types of monolithic zirconia crowns in terms of survival rate and fracture resistance after thermocycling and/or thermo-mechanical loading in a chewing simulator. Partially stabilized zirconia (PSZ) crowns with fiber-reinforced resin die assemblies (n=80) were fabricated using: multi-yttria-layered 5Y-PSZ/3Y-PSZ, multi-yttria-layered 5Y-PSZ/4Y-PSZ, monolithic 4Y-PSZ, and monolithic 3Y-PSZ as control (n=20). Half of the samples in each group were subjected to thermo-mechanical loading under 110N, 1.4Hz, 1.2 million cycles with simultaneous thermocycling (10,000cycles, 5-55°C). The other half were subjected to thermocycling alone. The samples were loaded to failure to measure their fracture resistance. The data were analyzed using by two-way ANOVA and Tukey's HSD post-hoc test (α=0.05). All specimens survived the aging protocols. The yttria content significantly affected the fracture resistance of the crowns (p<0.0001). The mean fracture resistance, from highest to lowest: 3Y-PSZ, 4Y-PSZ, followed by the two multi-yttria-layered systems. The mean difference between the two multi-yttria-layered systems were not statistically significant (p=0.98). The mechanical loading protocol did not affect the mean fracture resistance within each group (p=0.18). Within each group, there was no difference in fracture resistance after thermocycling alone and thermo-mechanical loading. However, increasing the yttria concentration at the occlusal third of the crown decreased its fracture resistance. The term "monolithic zirconia" alone without specifying the actual yttria content is misleading. This term represents different materials with different mechanical properties. The yttria content has an inverse relationship with the fracture resistance of zirconia crowns. The fracture resistance of multi-layer zirconia crowns is determined by the amount of the weaker zirconia phase at the occlusal part of the restoration rather than enforced by the stronger zirconia at the cervical part of the crown.

Fracture Resistance in Non-Vital Teeth: Absence of Interproximal Ferrule and Influence of Preparation Depth in CAD/CAM Endocrown Overlays-An In Vitro Study.

There is ample evidence to support the use of endocrowns to restore endodontic teeth. However, the influence of the position of the interproximal margins on fracture strength has not yet been studied. The aim was to determine the relationship between the apicocoronal position of the interproximal restorative margins and fracture resistance in nonvital teeth restored with CAD/CAM endocrown overlays. Forty extracted human maxillary premolars were prepared for endocrown overlay restorations without ferrule on the interproximal aspects and classified according to the position of the interproximal restoration margins in relation to the alveolar crest: 2 mm (group A), 1 mm (group B), 0.5 mm (group C), and 0 mm (group D). Fracture strength was measured using a universal testing machine applying a compressive force to the longitudinal tooth axis. Group A had a mean fracture resistance of 859.61 (±267.951) N, group B 1053.9 (±333.985) N, group C 1124.6 (±291.172) N, and group D 780.67 (±183.269) N, with statistical differences between groups. Group C had the highest values for fracture strength compared to the other groups (p < 0.05). The location of the interproximal margins appears to influence the fracture resistance of CAD/CAM endocrown overlays. A distance of 0.5 mm between the interproximal margin and the alveolar crest was associated with increased fracture resistance.

Fracture Resistance of Teeth Restored with Newer Methacrylate-Based Dental Composite Materials: An In Vitro Study

Introduction: Composite have evolved significantly due to the increase in the demand for a more esthetic and conservative approach in dentistry. Modifications have been made on the filler particle size and loading, followed by alterations in the resin matrix substance. Methacrylate-based composite with the addition of nanoparticles to the filler has been introduced in the market, providing improved esthetics and lower polymerization shrinkage. The present study was done to compare the fracture resistance of teeth restored using two newer methacrylate-based composite materials, along with the flexural strength of the composites. Methods: Sixty mandibular premolars were divided into two control groups of 10 teeth each and two experimental groups of 20 teeth. Group I − intact teeth with no preparations (n = 10), Group II − prepared but unrestored teeth (n = 10), Group III − teeth prepared and restored with a stackable nanohybrid methacrylate-based composite material (IPS Empress DirectTM), and Group IV − teeth prepared and restored with a packable submicron methacrylate-based composite material (Brilliant EverglowTM), respectively. The teeth were embedded in resin-filled PVC rings, and a compressive loading test was carried out for all groups at a cross-head speed of 0.5 mm/min. The flexural strengths of the two composite materials were also analyzed using three-point bending test using Universal Testing Machine. The statistical significance (P < 0.05) of the differences between the experimental groups was analyzed by ANOVA and Tukey post hoc test. Results: The mean fracture resistance was highest in Group IV (1877.37 ± 494.79) followed by Group III (1763.69 ± 392.51), Group I (1607.08 ± 283.48), and Group II having the least (1442.08 ± 373.66). The mean fracture resistance overall differed significantly between the four groups (P = 0.048). Tukey test showed fracture resistance differed significantly between Group II and Group IV (P = 0.042) and no significance among other groups. Conclusion: Fracture resistance was highest in the group restored with the packable submicron hybrid composite material. The packable submicron methacrylate-based composite material also showed higher flexural strength than stackable nanohybrid composite material.

Assessment of LuxaCore, Photo Core, and Core Max II on Fracture Resistance of Endodontically Treated Teeth Restored with ParaPosts and Fiber-Reinforced Composite Posts.

Objectives:The objective is to evaluate the efficacy of LuxaCore, Photo Core, and Core Max II on fracture resistance of endodontically treated teeth restored with ParaPosts and fiber-reinforced composite (FRC) posts.Materials and Methods:Ninety extracted mandibular first premolar teeth were randomly grouped into nine different groups with ten samples in each. I-FRC posts, II-FRC with Photo Core, III-FRC with LuxaCore, IV-FRC with composite core, V-FRC with Core Max II, VI-para Post (PP), VII-PP with Luxa core, VIII-PP with photo Core, IX-PP with Core Max II were compared for fracture resistance.Results:The mean fracture resistance (Newton) in group I was 452± 61.5, in group II was 412.6± 42.4 (higher from group I to group V), and lower in group VI to group IX (288 to 246.5). The mean fracture resistance of group II to V was 380.1±72.1 and group VI to IX was 62.8±70.6. The difference was statistically significant (0.001).Conclusion:FRC posts exhibited higher fracture resistance as compared to ParaPosts, and fracture resistance was not dependent on the type of material used.

Analysis of Fracture Resistance of Endodontically Treated Teeth with Different Restorative Materials: An In vitro Study.

Objectives:The objective of the study is to compare the fracture resistance of endodontic treated tooth restored with GIC, amalgam, and composite cements.Materials and Methods:Forty teeth were divided into 4 groups of 10 teeth each. Group I teeth were restored with silver amalgam. Group II teeth were restored with GIC. Group III teeth were restored with composite and Group IV teeth were control in which no alteration was performed. Testing machine applied force on teeth to detect fracture resistance.Results:The mean fracture resistance was maximum in Group IV (1050.2 N) followed by Group III (956.2 N), Group I (836.4 N), and Group II (766.4 N). The difference was statistically significant (P < 0.05). The mean difference of fracture resistance was significant (P > 0.05).Conclusion:Composite resin possesses highest fractures resistance as compared to GIC and silver amalgam.

Comparative evaluation of fracture resistance of anterior provisional restorations fabricated using conventional and digital techniques - An in vitro study.

Comparative evaluation of the fracture resistance of anterior provisional crowns fabricated by conventional and digital techniques. Department of Prosthodontic, PGIDS, Rohtak, An in-vitro - Comparative study. Thirty recently extracted maxillary central incisors were handpicked. Tooth preparation was done according to the principles of tooth preparation. A single-step impression technique was used for impression making of the prepared tooth and stone models were poured. Extracted teeth were divided into 3 groups (n = 10 each) based on provisional crown fabrication technique. A bis-acryl-based (Protemp 4 3M ESPE) resin was used to fabricate the provisional crowns by the conventional indirect technique. The rest of the stone models (20) were scanned using lab scanner (Dentsply Sirona InLab EOS X5). CAD/CAM provisional material (Dentsply Sirona multilayer PolyMethyl Methacrylate) PMMA disc was used for fabrication of provisional restoration through milling technique. 3D printed temporary provisional material (NextDent C&B resin) was utilized for 3D printed provisional crowns. Cementation of provisional crowns was done using eugenol free temporary luting cement (Templute, Prime dental). All cemented provisional crowns were subjected to load under Universal Testing Machine. The maximum load to produce fracture for each specimen was recorded in Newton (N). Shapiro-Wilk test was employed to test the normality of data. Kruskal- Wallis Test was used to compare the mean fracture resistance between all the groups. For intergroup comparison Mann-Whitney U Test was used. The mean fracture resistance of group I (Conventional technique) was found to be 558.8459700 ± 22.33 N; for group II (CAD/CAM technique) 960.8427200 ± 37.49 N and for group III (3D Printed technique) 1243.1774000 ± 68.18 N. Group I had the least fracture resistance value while group III showed maximum value. Provisional crowns fabricated using 3-D printing technique showed higher fracture resistance followed by CAD/CAM technique and conventional technique. Additive manufacturing of provisional crowns using 3-D printing technique could be considered a reliable and conservative method for the fabrication of stronger provisional restorations.

Comparative Evaluation of Fracture Resistance of Fiber-Reinforced Composite and Alkasite Restoration in Class I Cavity.

Background and Aim: Tooth-colored restorative materials for the restoration of decayed posterior teeth continue to gain popularity both among dental practitioners and patients. These materials have undergone a number of improvements in recent years to enhance their physical properties and diversify their use as a restorative material relevant to clinical practice. The aim of this study was to evaluate and compare the fracture resistance of two such advanced restorative materials, namely EverX Posterior, a fiber-reinforced composite and Cention N, an alkasite material in a Class I Cavity.Materials and Methods: Forty intact, caries-free human maxillary premolar teeth extracted for orthodontic purposes were divided randomly into four groups of 10 teeth each. Group I were unprepared teeth (intact teeth); Group II were unrestored teeth with class I cavity; Group III were teeth restored with fiber-reinforced composite (EverX Posterior); and Group IV were teeth restored using alkasite material (Cention N). Fracture resistance was recorded for all samples using a universal testing machine.Results: Higher fracture resistance was recorded in intact teeth group followed by EverX Posterior, Cention N and unrestored teeth, respectively. The teeth restored with EverX Posterior showed higher mean fracture resistance to fractures than those restored with Cention N. Teeth restored with EverX Posterior showed no significant difference in mean fracture resistance from Intact teeth while restored teeth with Cention N and unrestored teeth did.Conclusion: Fracture resistance of EverX Posterior was comparable to that of the natural tooth and was higher as compared to Cention N.

Comparative evaluation of the effect of adhesive restorative composite resins on the reinforcement of peri-cervical dentin: An in vitro study.

Background:Peri-cervical dentin (PCD) and its reinforcement play a crucial role in the fracture resistance of root canal-treated teeth.Aims:The aim of this study was to compare the fracture resistance of dual-cure, nano-hybrid, and short-fiber reinforced composite resins restored PCD with conventional hybrid composite (CHC) resin restored endodontically treated mandibular premolars.Settings and Design:Academic, in vitro study.Materials and Methods:The prepared mandibular premolar samples were randomly divided into five groups of 10 each. In Group 1, teeth were left intact. The remaining 40 teeth were endodontically treated and obturated as follows: In Group 2, teeth were obturated with gutta-percha till cementoenamel junction and restored with CHC. Teeth in Groups 3, 4, and 5 were obturated to a depth of 5 mm from the cervical line and restored with dual-cure, nano-hybrid, and short-fiber reinforced composite resins, respectively. Fracture resistance was tested using a universal testing machine.Statistical Analysis Used:One-way analysis of variance and post hoc Tukey's test.Results:Short-fiber reinforced composite resin showed a significantly higher mean fracture resistance value compared with other experimental groups. The mean fracture resistance values were obtained as Group 1 > Group 5 > Group 4 > Group 3 > Group 2.Conclusions:Reinforcement with short-fiber reinforced composite showed significantly higher fracture resistance compared with nano-hybrid and dual-cure composite resins.

Review of Marginal Adaptation and Fracture Resistance of Computer Aided Design/Computer Aided Manufacturer (CAD‐CAM) Fabricated Endo-crowns

Background: Zirconia-based restorations have become more popular in dentistry during the last two decades. Patients choose metal-free restorations, preferring materials with similar attributes to natural teeth and similar light scattering characteristics, resulting in a nice esthetic appearance. Restoring a root canal treated teeth is one of the hot topics today. endo crown materials can be either; feldspathic, glass-ceramic, monolithic hybrid ceramic or composite material. Considering the marginal gap of endocrown, an important cause of failure of treatment, the current study evaluated the marginal gap of CAD‐CAM concocted endo-crowns.&#x0D; Materials and Methods: This research is an analysis systemic review study was conducted between January 2020 and October 2021. We followed the PRISMA principles and recorded this systematic review using the PROSPERO database to find and identify published literature related to the marginal adaptation of CAD-CAM-fabricated endocrown. The search will include all relevant articles through the end of 2021. Finally, 24 papers on marginal clearance and fracture resistance in coronary arteries were reviewed.&#x0D; Results: The electronic database search yielded 98 studies that were relevant. After cross-referencing, further seven studies were added. After a full-text analysis and duplicate reduction, 74 of the 98 articles were eliminated. 5 clinical (prospective) studies, 19 in vitro studies were found.&#x0D; Conclusion: This analysis of the recent literature on the marginal seating integrity and fracture resistance of CAD/CAM made-up endo-crowns showed that the endo-crown had superior marginal seating integrity than classical full crown. CAM/CAM showed statistically significant higher mean fracture resistance than MAD/MAM.