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INTRODUCTION: On rare occasions, fractures of the tibial plateau may occur after uni-compartmental knee arthroplasty (UKA) and account for 2% of total UKA failures. The purpose of this narrative review is to identify and discuss potential risk factors that might lead to prevention of this invalidating complication. MATERIALS AND METHODS: Electronic database of Pubmed, Scopus, Cochrane and Google Scholar were searched. A total of 457 articles related to the topic were found. Of those, 86 references were included in this narrative review. RESULTS: UKA implantation acts as a stress riser in the medial compartment. To avoid fractures, surgeons need to balance load and bone stock. Post-operative lower limb alignment, implant positioning, level of resection and sizing of the tibial tray have a strong influence on load distribution of the tibial bone. Pain on weight-bearing signals bone-load imbalance and acts as an indicator of bone remodeling and should be a trigger for unloading. The first three months after surgery are critical because of transient post-operative osteoporosis and local biomechanical changes. Acquired osteoporosis is a growing concern in the arthroplasty population. Split fractures require internal fixation, while subsidence fractures differ in their management depending of the amount of bone impaction. Loose implants require revision knee arthroplasty. CONCLUSION: Peri-prosthetic fracture is a rare, but troublesome event, which can lead to implant failure and revision surgery. Better knowledge of the multifactorial risk factors in association with a thorough surgical technique is key for prevention.

Background The aim of this study was to develop a mathematically valid method of assessing fracture resistance of roots. The model developed used mesial roots of lower molars instrumented using stainless steel hand files (SS) and two rotary nickel-titanium (NiTi) systems. Methods Eighty human lower molars were selected and randomly divided into four groups (n = 20). After instrumentation, the root canals were obturated using thermoplasticized gutta percha. The roots were covered with a simulated periodontal ligament and mounted vertically in autopolymerizing acrylic in PVC tubes. Using a universal testing machine, the force to fracture (N) was applied and the maximum load (FL) was recorded. Remaining dentine volume was calculated and the fracture resistance (FR) was recorded. The data were analyzed using SPSS version 22 with P Results There were no significant differences among the instrumentation methods for FL but in FR the roots instrumented using rotary NiTi showed significantly lower values than control groups and SS files (P Conclusions Considering the effect of root length, volume of the root, and volume of the instrumented canal as well as the maximum failure load may be a more objective method of reporting fracture resistance of roots.

The prevention of root fractures of pulpless teeth is an important clinical issue to maintain healthy teeth through lifetime. The aim of this study was to examine a clinically effective treatment method for strengthening vulnerable pulpless teeth using CAD/CAM (computer-aided design/computer-aided manufacturing) fiber-reinforced post-core by conducting a fracture resistance test. A post-core made with a fiber-reinforced resin disk TRINIA (TR, SHOFU, Kyoto, Japan) was fabricated using a CAD/CAM system. The fiber-layer orientation of the CAD/CAM post-core was parallel to the axis of the restored tooth. A post-core using a conventional composite and a fiber post (CF) was also prepared. A fracture resistance test of teeth restored with the post-cores and zirconia crowns was conducted using a universal testing machine, and fracture patterns were identified by micro-CT observation. The fracture load of the roots restored with TR was 1555.9 ± 231.8 N, whereas that of CF was 1082.1 ± 226.7 N. The fracture load of TR was 43.8% that was significantly higher than that of CF (Student’s t-test, p &lt, 0.05). The restored teeth with CAD/CAM resin post-core were found to be repairable even after fracture. These results suggest that the CAD/CAM indirect fiber post-core has the potential to strengthen the vulnerable pulpless teeth.

Purpose: This study investigated influence of two conditioning methods and two luting cements on the fracture load of all-ceramic crowns. Materials and methods: A total of thirty-two CAD-CAM all-ceramic crowns, (Vita Mark II) were constructed on human upper premolars indicated for extraction and collected from department of oral surgery, faculty of dentistry, Mansoura University. The intaglio surfaces of 16 crowns were treated using acid (4.9% HF) with silane application. The other 16 crowns were conditioned using Monobond Etch & prime in one step. Each group divided into 2 subgroups (n=8) according to used type of luting cements. Self adhesive resin cement (Rely X U200) or multistep adhesive resin cement (Mutilinik Automix) were used for crowns cementation to appropriate teeth. Crowns were kept in water for 3 months but after cementations by one hour. Universal testing machine was used to record the fracture load for crowns (N). Results: Means fracture load of groups luted with multistep adhesive resin cement were significantly higher than means fracture load of test groups luted using self adhesive resin cement regardless of conditioning techniques used (P 0.05). Conclusions: Two techniques used for conditioning of Vita Mark II crowns did not affect significantly fracture load of these crowns. Multilink adhesive resin cement improved fracture loads of Vita Mark II crowns compared to RelyX U200.

Background: This study investigated the influence of erbium‑doped: yttrium aluminum garnet (Er:YAG) laser on the pull‑out fracture load of fiber‑reinforced composite (FRC) posts luted to dentin with different resin cements. Materials and Methods: In this in vitro experimental study, 90 premolars were endodontically treated. The post spaces were prepared, and the teeth were divided into three groups dependent on the cement applied for luting FRC posts: Group 1: An etch‑and‑rinse system, Group 2: A self‑etch cement, and Group 3: A self‑adhesive cement. After 6 months’ storage and thermocycling, each group was divided into three subgroups (n = 10) according to the treatment applied for removing the posts; subgroup 1: Control, subgroup 2: Treatment with Er:YAG laser at 250 mJ, 20 Hz, and subgroup 3: Treatment by Er:YAG laser at 300 mJ, 10 Hz. The pull‑out load was recorded in Newton. The data were analyzed by two‑way ANOVA at P < 0.05. Results: The fracture load was significantly affected by the cementation group (P = 0.005) and treatment subgroup (P = 0.008). The pull‑out load of self‑etch cement was significantly greater than that of the self‑adhesive and etch‑and‑rinse systems (P < 0.05). Treatment with Er:YAG laser caused a significant reduction in pull‑out load of FRC posts (P < 0.05). Conclusion: The fracture load of fiber posts is influenced by the type of cement and treatment applied. Post removal would be less challenging when using a self‑adhesive or conventional etch‑and‑rinse cement or using Er:YAG laser at the FRC‑resin interface. Key Words: Lasers, post technique, resin cements, erbium

To evaluate the effects of post length, post material, and substance loss on the fracture resistance of endodontically treated mandibular premolars.A total of 96 extracted human mandibular first premolars were endodontically treated and divided into 12 test groups (n = 8 each) based on the number of residual walls (one/two), post material (glass-fiber/titanium), and post length (5 mm, 7.5 mm, and 10 mm). After luting the posts, specimens received a composite resin core and a crown preparation with a 1.5-mm ferrule. Cast cobalt-chromium crowns were cemented using glass-ionomer cement. After 1,200,000 chewing cycles with a load of 49 N and simultaneous thermocycling (5°C to 55°C), specimens were quasi-statically loaded at 30 degrees to the longitudinal axis of the tooth until fracture. Fracture loads were analyzed using three-way, two-way, and one-way analysis of variance (α = .05). Fracture modes were examined under a stereomicroscope (×25) and recorded.Fracture loads ranged from 642 ± 190 N (one wall, glass fiber, 5 mm) to 1,170 ± 130 (two walls, titanium, 7.5 mm). The mean fracture load of titanium posts was significantly higher than that of glass-fiber posts (P.001), and the 7.5-mm post length exhibited significantly higher fracture loads than groups with 5-mm and 10-mm post length (P = .008).Teeth restored with titanium posts revealed considerably higher fracture resistance than teeth restored with glass-fiber posts, especially if 7.5-mm-length posts were used.

Hip fracture is regarded as the most significant osteoporotic fracture in terms of health consequences, quality of life, and cost

Background The periprosthetic femoral fracture is one of the most severe complications after total hip arthroplasty and is associated with an increased mortality. The underlying causes and the patient- and implant-specific risk factors of periprosthetic femoral fractures remain insufficiently understood. The aim of this study was to gain a more profound understanding of the underlying fracture mechanisms and to provide experimental datasets for validation of computational models. Methods Six cadaveric femurs were implanted with straight hip stems (Zweymueller design) and loaded until fracture reproducing the clinically relevant load cases stumbling and sideways fall. Displacements and the strain distribution on the surface of the femurs and implants, as well as the fracture load and implant subsidence were measured. Findings For the load case stumbling the mean fracture load was 6743 N and two different mechanisms leading to fracture could be identified: high subsidence with low femoral bending and small subsidence with high femoral bending. For the load case sideways fall the mean fracture load was 1757 N and both tested femurs fractured due to a rotation of the hip stem around its own axis. The detailed datasets provided by this study can be used in future computational models. Interpretation We demonstrated that the underlying fracture mechanisms of periprosthetic femoral fractures can be fundamentally different in the load case stumbling. The seating and exact position of the hip stem in the femur may correlate with implant subsidence and therefore lead to different types of fracture mechanisms resulting in different patient-specific fracture risks.

Introduction The objective of this study was to examine the influence of instrument taper on the fracture resistance of endodontically treated roots under in vitro experimental conditions. Methods In total, 58 maxillary canines complying with the inclusion criteria were sectioned at approximately 13 mm from the apex. The roots were standardized with respect to the buccolingual-mesiodistal diameter and weight before being randomly distributed into 3 experimental groups (n = 14) and 1 control group (n = 16). The roots in group 1 were instrumented with hand files up to file 40/.02 and groups 2 and 3 with Mtwo (VDW, Munich, Germany) rotary files up to files 40/.04 and 40/.06, respectively. After mechanical preparation, the roots were obturated with gutta-percha and sealer. Roots in group 4 acted as uninstrumented controls. A vertical load was applied to each specimen using a universal testing machine until the roots fractured. Data were statistically analyzed by introducing an innovative approach integrating 1-way analysis of variance, confirmatory factor analysis, and regression analysis. Results The mean fracture load was 357.47 ± 110.54 N for the control group, 338.86 ± 105.23 N for group 1, 297.74 ± 77.31 N for group 2, and 280.10 ± 68.51 N for group 3. However, only the difference between group 3 and the control group was statistically significant (P Conclusions After instrumentation using hand files up to file 40/.02 and rotary files up to files 40/.04 and 40/.06, only the last appeared to change the fracture resistance of endodontically treated roots.

The present investigation carried out to analyze the breaking load of single lap joint using hybrid joining techniques for alloy steel AISI 4140 and mild steel as base material by experimentally and optimized by Taguchi method and neural network. The six samples of lap joints were prepared namely: bolted joint (BJ); adhesive joint (AJ); welded joint (WJ); bolted-welded joint (BWJ); adhesive-welded joint (AWJ) and adhesivebolted joint (ABJ). The breaking load of the joints in terms of breaking load and elongation were evaluated for each joint. The effect of the adjustment attached to the joint on the breaking load and elongation were evaluated. Taguchi method was applied for given input parameters and L4 design of experiments was used. The breaking load and elongation were taken as output response. The predicted values by Taguchi method were used as target values in neural network fitting curve. Neural network fitting tool was used to check whether the obtained values were near the target value or not. Based on the achieved results, the maximum breaking load and elongation were found for bolted-welded joint.

Aim The aim of this in vitro study was to evaluate the effect of accelerated artificial aging (AAA) and fatigue on the biaxial flexural strength (BFS) of three types of monolithic high-translucency zirconia restorations compared with conventional low-translucency zirconia restorations. Materials and methods Four groups of 20 disc-shaped specimens (10 × 1.2 mm) were made from the following computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia blocks: Low-translucency zirconia (Ceramill ZI-LT) as a control, and three brands of high-translucent zirconia (Lava Plus, Ceramill Zolid White, and Copran Monolithic HT). Ten discs from each group were subjected to the BFS test using the universal testing machine. The other 10 discs from each group were subjected to AAA (thermocycling, 3,500 cycles) and fatigue (250,000 cycles) before the fracture test. The definitive fracture load was recorded, and the BFS was calculated in accordance with International Organization for Standardization (ISO) 6872. The data were analyzed with one-way analysis of variance (ANOVA), Scheffe post hoc, and Mann-Whitney U test. Data analyses were evaluated at a significance level of p Results Significant differences were detected in the BFS among the four groups before AAA and fatigue. The mean BFS was highest with Ceramill ZI (935.3 ± 47.1 MPa), and least in Ceramill Zolid White (685.7 ± 32.6 MPa). After AAA and fatigue, significant differences were reported where the mean of BFS was highest with Copran Zr-i Monolithic HT (777.5 ± 21.2 MPa), and least in Ceramill Zolid White (576.0 ± 36.3 MPa). Furthermore, Mann-Whitney U test showed that AAA and fatigue significantly affect the BFS of each material individually. Conclusion The AAA and fatigue significantly affected the BFS of the monolithic high-translucency zirconia restorations. Clinical significance Although monolithic high-translucency zirconia had significantly lower BFS than conventional zirconia tested in this study, they still have sufficient strength for clinical use.

In this paper, first the fracture load, the crack initiation angle and the crack trajectory are experimentally measured for the round-tip V-notched Brazilian disk specimen made of polymethyl-methacrylate under compressive-shear loading. Then, the fracture load and the crack initiation angle are predicted by using the extended finite element method on the basis of the linear cohesive crack criterion. The fracture trajectory of the round-tip V-notched Brazilian disk specimens is also estimated by means of the extended finite element method and the incremental methods. Both the experimental observations and the theoretical fracture models indicate that although the notch bisector line is under compressive-shear loading, one half of the notch border still sustains tensile stresses and fracture takes place from this half. A very good agreement is shown to exist between the theoretical predictions and the experimental results for various notch opening angles and different notch radii.

The purpose of this study was to evaluate and to compare the fracture load and the fracture pattern of monolithic and veneered zirconia posterior fixed dental prostheses (FDPs). Twenty standardized steel dies were prepared to receive posterior 3-unit FDPs. Specimens were randomly divided into 2 groups (n=10): (1) Lava Zirconia, and (2) Lava Plus. All FDPs were cemented using glass ionomer cement and subjected to thermal and mechanical cycling at 5-55ºC with a 30-s dwell time for 120,000 masticatory cycles. All specimens were subjected to a three-point bending test until fracture. Data were statistically analyzed using Student's t test, paired t-test and Weibull statistics (α=0.05). No differences were observed in fracture load between the groups. Veneering ceramic fractured before than framework in veneered zirconia group. The fracture pattern was different. The tested groups demonstrated clinically acceptable fracture load values. Monolithic zirconia solves the chipping problem.

To investigate two-body wear (2BW) and fracture load (FL) of monolithic ceramics after different surface pretreatments. Zirconia (MOZ), lithium-disilicate (LIT), and leucite-reinforced (LEU) specimens (n = 60/group) were manufactured with CAD/CAM-technology and underwent (n = 15/subgroup): 1) grinding + polishing (GrPo), 2) grinding + glazing (GrGz), 3) grinding (Gr), or 4) glazing (Gz). Scanning electron microscope (n = 3/subgroup) and 3D measurements of the ceramic crowns and antagonists (N = 180) were performed to determine 2BW before and after 120,000/1,200,000 masticatory cycles. FL was examined for all specimens (N = 180). Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Scheffe post hoc, Kruskal-Wallis, Mann-Whitney-U, and Wilcoxon (p

Purpose To test three potential prosthetic material options for zirconia implants in regard to their mechanical properties, loading and retention capacity as well as to record abrasion after chewing simulation followed by thermocyclic aging. Methods Molar crowns (n = 96) of three different computer-aided design/computer-aided manufacturing (CAD/CAM) materials were produced and cemented on zirconia implants (ceramic.implant, Vita) with a diameter of 4.5 mm. Monolithic zirconia (Vita YZ [YZ] with RelyX Unicem 2 Automix [RUN], polymer-infiltrated ceramic (Vita Enamic [VE]) with Vita Adiva F-Cem [VAF] and acrylate polymer (CAD Temp [CT]) with RelyX Ultimate [RUL]. Fracture load and retentive force of the crowns were measured after 24 h water storage at 37 °C and after a chewing simulation followed by thermocyclic aging. Abrasion was recorded by matching stereolithography-data of the crowns obtained before and after chewing simulation. Additionally, the mechanical properties and bonding capabilities of the crown and cement materials were assessed. Results Fracture load values were significantly highest for YZ > VE = CT. Retention force values did not differ significantly between the materials. The aging procedure did not affect the fracture load values nor the retention force significantly. Abrasion depth of the crowns was lowest for YZ followed by VE and CT. On unpolished crowns, abrasion of YZ and VE tended to be higher than on polished specimens. Conclusions Based on the obtained in-vitro results, all tested materials can be recommended for the use on zirconia implants, although CT is only approved for temporary crowns. The loading and retention capacity of the materials were not significantly affected by aging.

Aesthetic alternatives to stainless-steel crowns for restoring primary molars attain growing interest. We studied the mechanical properties of prefabricated zirconia crowns and conventional crowns. Three brands of prefabricated zirconia crowns were compared with computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crowns, preveneered stainless-steel crowns, and conventional stainless-steel crowns regarding: (i) fracture load under each of three conditions [no pretreatment, artificial aging in saliva for 12 wk, and after chewing simulation/thermocycling (1.68 × 106 cycles/5-55°C)]; and (ii) survival rate during chewing simulation, considering decementation, fracture, chipping, fatigue cracks, and occlusal holes. Without pretreatment, the prefabricated zirconia crowns showed mean fracture load values between 893 N and 1,582 N, while the corresponding values for CAD/CAM zirconia crowns and preveneered stainless-steel crowns were 2,444 N and 6,251 N. Preveneered stainless-steel crowns showed significantly lower fracture loads after artificial aging (5,348 N after saliva aging; 3,778 N after chewing simulation) than without artificial aging, whereas the fracture load of zirconia crowns was not influenced negatively. The survival rate of the different groups of zirconia crowns and preveneered stainless-steel crowns during chewing simulation was 100%, but only 41.7% for the stainless-steel crowns. These in-vitro data suggest that prefabricated zirconia crowns are aesthetically and durable alternatives to stainless-steel crowns for primary molars.

Loss-of-Coolant-Accident (LOCA) is a design basis accident that is considered in safety analyses for LWR. This paper discusses crack formation in one-side oxidized Zircaloy-4 cladding with LOCA oxidation quench experimental data. Two types of test pins were used in these experiments. One consisted of a Zircaloy-4 cladding tube and alumina pellets. Another comprised a Zircaloy-4 cladding tube alone. The experimental results showed that the fracture load in the latter cases was larger by about 1000 N, and cracks in the oxide layer were clearly observed in the former cases but not in the latter cases. This trend suggested that the order of cracks formed in cladding during LOCA quench conditions should be, first in the α-Zr(O) layer, and then in the oxide, finally in the prior-β layer when the fracture of cladding occurs. The formation of cracks in the oxide was considered to be related to the maximum thermal stress generated in the cladding during quench. RANNS computation suggested that the maximum radial temperature difference in the former case tended to be larger than that in the latter case, and the radial temperature difference increases considerably with off-center pellets, which might also affect crack formation.

Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a univer-sal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load.

The main aim of the paper is to show that the expressions proposed for evaluation of the critical value of the J-integral in notches (Jcr) can be applied for mixed mode loading, too. So, fracture load of plates weakened by U-notches under mixed mode loading has directly been evaluated by J-integral. The J-integral for plates with different mode mixity has been evaluated by using the finite element software ANSYS. Then the fracture load has been assessed by means of J = Jcr. The results of fracture load using J-integral have been compared with experimental data for martensitic steel plates taken from the literature and good agreement was found.

Aims: This study aims to evaluate the effective method for restoring badly mutilated primary anterior teeth, by comparing the fracture load resistance of polyethylene fiber post with composite resin short post containing omega-shaped stainless steel wire. Subjects and Methods: Sixty carious deciduous incisors, with 2/3 root length remaining, were endodontically treated and divided into two groups. Group I consisted of thirty samples of Ribbond fiber post and Group II consisted of thirty samples of resin short post with omega-shaped stainless steel wire. They were tested under the universal testing machine for fracture resistance, and the fracture site was noted under the stereomicroscope. Statistical Analysis Used: Data were statistically analyzed using Windows IBM SPSS 8.0 and Student's t-test. Results: Resin short post with omega-shaped stainless steel wire showed a statistically significant high fracture resistance and retention when compared with Ribbond fiber post. Conclusions: Insufficient fiber length and shape of the fiber post had reduced its resistance to fracture, whereas resin short post and omega-shaped wire have got synergistic action when they are used together resulting in increased resistance and retention to fracture.

Background: The aim of this in vitro study was to examine the fracture load of composite veneers using three different preparation designs. Material and methods: Fifteen extracted, intact, human maxillary central incisors were selected. Teeth were divided into three groups with different preparation design: 1) feather preparation, 2) bevel preparation, and 3) incisal overlap- palatal chamfer. Teeth were restored with composite veneers, and the specimens were loaded to failure. The localization of the fracture was recorded as incisal, gingival or combined. Results: Composite veneers with incisal overlap – palatal chamfer showed higher fracture resistance compared to feather preparation and bevel preparation. The mean (SD) fracture loads were: Group 1: 100.6±8.0 N, Group 2: 107.4±6.8 N, and Group 3: 122.0±8.8 N. The most common mode of failure was debonding for veneers with feather preparation and fracture when incisal edge is reduced. The most frequent localization of fracture was incisal. Conclusion: The type of preparation has a significant effect on fracture load for composite veneers. This study indicates that using an incisal overlap– palatal chamfer preparation design significantly increases the fracture resistance compared to feather and bevel preparation designs. Key words: composite veneers, preparation design, fracture resistance

In this work, the unified constraint-based FAD (failure assessment diagram) assessment methodology has been investigated and developed for ductile fracture in cracked pipes. Two unified constraint parameters Ap and Ad are utilized to incorporate both in-plane and out-of-plane constraints. The results show that the FAD approaches based on two-parameter K-Ap and K-Ad can predict similar fracture initiation loads. With decreasing crack length and depth, the constraint level decreases and fracture toughness increases, thus the predicted fracture load increases. For some shallow and short pipe cracks with lower constraints, the unified constraint-based FAD assessment can reduce conservatism degree of the conventional FAD assessment. For some deep and long cracks, their constraint levels may be higher than the standard plane strain specimen, and the application of the unified constraint-based FAD assessment approaches may eliminate non-conservative assessment in the conventional FAD approach. The unified constraint-based FAD approaches and CDF (crack driving farce) approaches using parameters Ap and Ad can produce similar fracture prediction results, thus they are basically equivalent.

To determine the effect of veneering material and framework design on fracture loads of implant-supported zirconia molar fixed dental prostheses (FDPs).Sixty-six zirconia FDPs were manufactured onto two implants and classified as uniform thickness (UT) or anatomic design (AD). These framework design groups were then further divided into three subgroups (n=11): feldspathic porcelain-veneered zirconia FDPs (PVZ), indirect composite-veneered zirconia FDPs (IVZ), and metal-ceramic FDPs (MC). The FDPs were luted on the implant abutments and underwent fracture load testing. Significant differences were assessed by the Kruskal-Wallis test and Mann-Whitney U-test (α=0.05).For UT group, median fracture load was significantly higher for the IVZ (1.87kN) and MC (1.90kN) specimens than for the PVZ specimens (1.38kN) (p0.05). In the AD group, the IVZ specimens had the highest median fracture load (4.10kN) of the three groups tested. The AD group exhibited higher median fracture loads than the UT group in all subgroups.Indirect composite appears to be a useful alternative to feldspathic porcelain as the layering material for implant-supported zirconia FDPs. The AD group had higher fracture loads than UT group. In addition, implant-supported indirect composite-veneered zirconia-based FDPs appear to be clinically feasible.

Indirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated from three particle-filled composite CAD/CAM materials and one 3D-printed composite material. Lava Ultimate, Cerasmart and Brilliant Crios were used as particle-filled composite CAD/CAM material and els-3D Harz as 3D-printed composite material. For each group, crowns with three different material thicknesses (0.5/1.0/1.5 mm) were fabricated. Control group was composed of ceramic-based CAD/CAM materials e.max CAD and Enamic. Totally, n = 180 crowns were fabricated and adhesively seated on SLA fabricated dies. Thermomechanical loading and fracture testing were performed. The data for fracture loading force were statistically analyzed by two-way ANOVA followed with multiple comparisons by post hoc Tukey’s test (α = 0.05). In contrast to ceramics, all particle-filled composite crowns with 0.5-mm thickness survived fatigue testing. Forces varied statistically significantly. Brilliant Crios showed highest maximum loading force with 1580.4 ± 521.0 N (1.5 mm). Two-way ANOVA indicated that both the material and the thickness affected the fracture load (p

The aim of the current investigation was to evaluate the fracture resistance of one-piece zirconia oral implants with and without all-ceramic incisor crowns after long-term thermomechanical cycling. A total of 48 implants were evaluated. The groups with crowns (C, 24 samples) and without crowns (N, 24 samples) were subdivided according to the loading protocol, resulting in three groups of 8 samples each: Group “0” was not exposed to cyclic loading, whereas groups “5” and “10” were loaded with 5 and 10 million chewing cycles, respectively. This resulted in 6 different groups: C0/N0, C5/N5 and C10/N10. Subsequently, all 48 implants were statically loaded to fracture and bending moments were calculated. All implants survived the artificial aging. For the static loading the following average bending moments were calculated: C0: 326 Ncm, C5: 339 Ncm, C10: 369 Ncm, N0: 339 Ncm, N5: 398 Ncm and N10: 355 Ncm. To a certain extent, thermomechanical cycling resulted in an increase of fracture resistance which did not prove to be statistically significant. Regarding its fracture resistance, the evaluated ceramic implant system made of Y-TZP seems to be able to resist physiological chewing forces long-term. Restauration with all-ceramic single crowns showed no negative influence on fracture resistance.

Handgun bullets fired toward the windshield of an automobile sometimes ricochets. In such a case, we must estimate the type of bullet and direction of shooting from the damaged windshield. The purpose of this study is to obtain a method to estimate the fired direction of a handgun bullet from the fractured windshield. We test fired bullets to an automobile windshield with various incidence angles. The thickness of the windshield is slightly different from model to model of the automobiles. In the beginning, we examined the strength of the automobile windshield of various car models. First, we examined the static failure strength of the windshield by an indentation test. In this test, fracture load and the amount of indentation were measured on windshield samples cut from ten models of Japanese automobiles. Next, we test fired a handgun in order to examine the relation between the trajectory of a bullet and the collision marks on the windshield. The cartridges used in these test firings were 38SPL. lead round nose (LRN) bullet and full metal cased (FMC) bullet. In the results of static indentation test for different car models, there was found to be almost no differences in the relationship between fracture load and indentation depth. With the LRN bullet, bullets perforated the windshield when the incidence angle was less than 45 degrees and ricocheted when the incidence angle was greater than 60 degrees. In these cases, a characteristic damage was left on the windshield. On the other hand, FMC bullets of 38SPL. perforated the windshield when the incidence angle was less than 60 degrees and ricocheted when the incidence angle was greater than 70 degrees. Based on these results, we proposed a method to estimate the direction of shooting in criminal cases in which a bullet was fired on an automobile windshield.

Objective: To evaluate the fracture resistance of endodontically treated teeth reinforced with cast titanium posts and prefabricated glass-fiber posts with different diameters. Materials and Methods: 50 recently extracted human maxillary central incisors were endodontically treated and randomly divided into 5 groups of 10 specimens each: Group A: 1.35mm diameter of cast titanium post; Group B: 1.5mm diameter of cast titanium post; Group C: 1.375mm diameter of prefabricated fiber post; Group D: 1.5mm diameter of prefabricated fiber post; Group E: resin restoration. All specimens were subjected to fracture resistance testing in a universal testing machine, statistical analysis was performed and the fracture modes were analyzed. Results: The mean fracture resistance of five groups as follows: 404.22±73.92N for group A, 488.17±78.68N for group B, 280.32±45.23N for group C, 317.53±50.87N for group D, 222.76±38.67N for group E. The fracture resistance of restored teeth between group C and group D had no significant difference (P>0.05). The fracture resistance of the rest pairwise group comparisons had significant difference (P

Objective: This study aimed to evaluate the fracture load of endocrown restorations and fiber-reinforced composites (FRCs) fabricated through computer-aided design/computer-aided manufacturing (CAD-CAM) for post–cores of anterior teeth. Materials and Method: Forty post–core-supported crowns and endocrowns were fabricated through CAD-CAM on a canine root zirconia model (Ice Zirconia, ZirkonZahn GmBH, Bruneck, Italy). The static load-bearing capacity was measured on the following restoration groups: Group 1: zirconia crown (Prettau anterior, ZirkonZahn GmBH) retained with CAD-CAM one-piece FRC post-core crown system (experimental CAD-CAM FRC block); Group 2: zirconia crown (Prettau anterior) retained with FRC post (GC Corp., Tokyo, Japan) with discontinuous fiber composite (EverX posterior, GC Corp) core; Group 3: zirconia endocrown (Prettau anterior); and Group 4: lithium disilicate ceramic endocrown (IPS e.max CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein) (n = 10/per group). After the adhesive cementation of crowns/endocrowns to the zirconia root model, a load was applied at 45° to the long axis of the teeth and measured using a universal testing machine. The fracture modes were visually examined. The statistical analyses were performed using one-way ANOVA and Tukey post-hoc tests (p < 0.05). Results: The fracture load significantly differed among the groups (p < 0.05) and was ranked as follows: Group 3 (1168 ± 141 N) > Group 4 (721 ± 96 N) ≥ Group 1 (680 ± 86 N) > Group 2 (534 ± 36 N). Conclusion: Endocrown monoblock restorations can be used as an alternative to fiber-reinforced post–core supported crown restorations.

Estimating the risk of osteoporotic fractures is an important diagnostic step that needs to be taken before medicinal treatment. Densitometry-based criteria are normally used in clinical practice for this purpose. However, densitometry-based techniques could not explain all low-energy fractures. As patient-specific finite element (FE) models allow for consideration of other parameters (e.g. load conditions) that are known to be associated with fracture, they are considered promising candidates for more accurate fracture risk estimation. Nevertheless, they are often time consuming, expensive, and complex to build and may need the type of expertise that is not normally available in clinical settings. In this study, we report the development of an automated platform for estimating proximal femur fracture loads using patient-specific 2D FE models generated using dual-energy x-ray absorptiometry (DXA) scans. First, a statistical shape and appearance model (SSAM) is built using DXA scans of patients screened for osteoporosis following a low energy fracture. SSAM is then used together with Active Appearance Models (AAM) for automated segmentation of the proximal femur from new unseen DXA scans. The mean point-to-curve error of the automated procedure, i.e. 1.2-1.4 mm, is shown to be only slightly larger than the intra-observer variability of manual segmentation, i.e. 1.0 mm. Moreover, the developed platform automatically meshes the segmented shape, assigns density-based mechanical properties, assigns loads and boundary conditions, submits the 2D FE model for solution, and performs post-processing of the 2D FE simulation data to determine fracture loads. The fracture loads predicted using the manually generated and automatically generated 2D FE models are shown to be very close with a mean difference of around 8.8%. Repeated measures ANOVA showed no significant differences between the fracture loads calculated using FE models manually generated by three independent observers and those calculated using the automatically generated FE models (p > 0.05). (C) 2014 Elsevier Ltd. All rights reserved.

SUMMARY Purpose To evaluate the fracture load and survival rate of weakened and non-weakened roots restored with different intracanal posts. Methods Eighty teeth (16 mm) were prepared to a length of 10 mm with a custom drill. Fifty roots were weakened with a tapered diamond drill, and 30 roots were not. The specimens were embedded with acrylic resin up to 3 mm from the coronal aspect, and the periodontal ligament was simulated. The 50 weakened roots were restored with (n=10) CPC-gold (cast post and core made of gold alloy), CPC-Ni (cast post and core made of Ni-Cr alloy), FP (glass fiber posts), FP-W (glass fiber posts with a wider coronal diameter), and FP-CR (fiber posts relined with composite resin). The 30 nonweakened roots were restored with (n=10) CPC-gold, CPC-Ni, and FP. All of the posts were adhesively cemented. All of the specimens were mechanically cycled (37°C, 45°, 130 N, 2.2 Hz, and 1.5 million pulses) and evaluated after every 5 × 104 cycles to evaluate the presence of cracks as a primary outcome (event). The specimens that survived cycling were subjected to a fracture load test (load application on the palatal aspect at a 45° inclination). Failure mode was classified as favorable (above the simulated bone level) and catastrophic (below the simulated bone level). Survival rates were estimated using the Kaplan-Meier method. Fracture load data were analyzed using the Kruskal-Wallis test (α=0.05) for weakened roots, one-way analysis of variance, and Tukey test (p Results For the preliminary survival results, FP-W showed a higher survival rate when compared with CPC (gold/Ni). For the fracture load (N), the statistical analysis (p FP (282.2) = FP-W (274.1) = FP-RC (216.6). No differences were observed for the groups that were nonweakened (majority of favorable failures): CPC-gold (459.3) = CPC-Ni (422.0) = FP (347.9). Weakened roots restored with CPC-gold promoted high values of load fracture and unfavorable failure rates. Conclusion Cast post and cores or fiber posts can be used for restoring nonweakened roots. However, for weakened roots, a fiber post with a wider cervical emerging diameter appears to be a better alternative when compared with cast post and cores.

Aim The present in-vitro study aimed to compare the fracture resistance of mandibular premolars, obturated after instrumentation by Self-Adjusting File (SAF), ProTaper NEXT (PTN) and WaveOne (WO). Method Sixty extracted mandibular premolars were decoronated to obtain the root length of 15 mm. The samples were divided into 4 experimental groups: Group 1 without instrumentation (control), Group 2 instrumented with SAF, Group 3 with PTN (X1 and X2) and Group 4 with WO (primary). Following instrumentation, the samples were obturated by cold lateral compaction technique using gutta-percha and AH Plus sealer. A week later, after the sealer was completely set, a vertical load was applied to the specimen's canal until fracture. Statistical analysis was performed. Results The mean fracture load exhibited significant difference (p 0.05), but a significant difference with group 4 (p Conclusion Teeth instrumented by SAF exhibited a better fracture resistance.

The fracture of zirconia abutments has been reported relative to different amounts of reduction. Data are not available to demonstrate whether the apical vertical reduction of a zirconia abutment at different levels can be achieved while maintaining an acceptable load-to-fracture value.The purpose of this study was to evaluate in vitro the effect of different levels of preparation of zirconia implant abutments on the fracture load.Twenty-seven zirconia abutments (NobelProcera Abutment Zirconia) and 27 implant analogs (NobelReplace Implant Replicas) were divided into 3 groups of 9 abutments and 9 implant analogs. The Zu group (n=9) without any modification and with a chamfer margin width of 0.8 mm served as the control. The Zp1 group (n=9) was prepared with a chamfer margin width of 0.8 mm and with a 1-mm step in the labial margin. The Zp2 group (n=9) was prepared with a chamfer margin width of 0.8 mm and with a 1.5-mm step in the labial margin. The zirconia abutment was attached to the implant analog and fixed in a customized steel mounting table. The abutment-implant complex was immersed in saliva substitute to simulate the clinical oral environment. A 250 000 cycle sinusoidal fatigue load that ranged between 10 N and 210 N was applied to the specimens by using a universal testing machine. Subsequently, the specimens were loaded to fracture. One-way ANOVA and the Tukey post hoc test were used to compare the groups statistically (α=.05).The mean (standard deviation) values of the abutment load to fracture were as follows: Zu group = 567.3 ± 35.4 N; Zp1 group = 445.4 ± 41.0 N; Zp2 group = 430.5 ± 39.4 N. The lowest abutment load-to-fracture value was in the Zp2 group (408.6 N), whereas the highest abutment load-to-fracture value was in the Zu group (591.4 N). A significant (P.05) difference was found between the Zu group and the other groups, but no significant difference was found between the Zp1 group and the Zp2 group. The primary mode of fracture (67%) was at the abutment-analog interface.Preparation of prefabricated zirconia abutments had a statistically significant negative effect on the abutment load-to-fracture values.

The purpose of this paper is to develop clinching technology using AC servo direct-drive device. The control systems of AC servo direct-drive device are designed to control the clinching. It could accurately control the connection of aluminum alloy 6061 sheets with the round joint. The joint quality is evaluated by the tensile tests. The results of the tensile tests shown that fracture load satisfied the required joint strength. Meanwhile, AC servo direct-drive device also could ensure the efficiency and quality of clinching process.

Background Current clinical methods for fracture prediction rely on two-dimensional imaging methods such as dual-energy X-ray absorptiometry and have limited predictive value. Several researchers have tried to integrate three-dimensional imaging techniques with the finite element (FE) method to improve the accuracy of fracture predictions. Before FE models could be used in clinical settings, a thorough validation of their accuracy is required. In this paper, we try to evaluate the current state of accuracy of subject-specific FE models that are used for prediction of the fracture load of proximal femora. Methods All the studies that have used FE for prediction of fracture load and have compared the predicted fracture load with experimentally measured fracture loads in vitro are identified through a systematic search of the literature. A quantitative analysis of the results of those studies has been carried out to determine the absolute prediction error, percentage error, and linear correlations between predicted and measured fracture loads. Findings The reported coefficients of determination (R2) vary between 0.773 and 0.96 while the percentage error in prediction of fracture load varies between 5 and 46% with most studies reporting percentage errors between 10 and 20%. Interpretation We conclude that FE models, which are currently used only experimentally, are in general more accurate than clinically used fracture risk assessment techniques. However, the accuracy of FE models depends on the details of their modeling methodologies. Therefore, modeling procedures need to be optimized and standardized before FE could be used in clinical settings.

Objectives: To test the fracture strength of weakened bovine incisors endodontically treated with mineral trioxide aggregate (MTA), cal- cium phosphate bone cement (CPBC) or fibre reinforced composite (FRC) posts, and to evaluate the fracture mode. Methods: Weakened bovine incisors (n = 75), standardized according to the dentinal wall thickness at the cervical area, were randomly assigned to one control group and three experimental groups. Unfilled teeth were assigned to group 1 (n = 20) and served as control group. Group 2 (n = 17) consisted of teeth filled with MTA. In group 3 (n = 18), the incisors were filled with CPBC and in group 4 (n = 20) with FRC posts. All specimens were subjected to load at a cross-head speed of 60 mm min 1 until fracture occurred. The initial (IL) and final fracture (FL) loads (N) were recorded, and the failure mode among the different groups was evaluated. Results: ANOVA showed a sta- tistically significant difference in fracture load among the groups. Tukey's test revealed a significant difference for the IL between the control group and the experimental groups with exception of the MTA group. The FL was not significantly different among the experimental groups. A high per- centage of favourable fractures was seen in the FRC and CPBC groups. Conclusion: FRC posts and CPBC could be promising materials to strengthen non-vital structurally compromised teeth.

Objectives: The objective of this study is to evaluate, in vitro, the thickness of immediate dentin sealing (IDS) materials on full crown preparations and its effect on the fracture load of a reinforced all-ceramic crown. Materials and Methods: Sixty premolars received full crown preparation and were divided into the following groups according to the IDS technique: G1-control; G2-Clearfil SE Bond; and G3-Clearfil SE Bond and Protect Liner F. After the impressions were taken, the preparations were temporized with acrylic resin crowns. IPS empress 2 restorations were fabricated and later cemented on the preparations with Panavia F. 10 specimens from each group were submitted to fracture load testing. The other 10 specimens were sectioned buccolingually before the thicknesses of Panavia F, Clearfil SE Bond and Protect Liner F were measured in 10 different positions using a microscope. Results: According to analysis of variance and Tukey′s test, the fracture load of Group 3 (1300 N) was significantly higher than that of Group 1 (1001 N) (P < 0.01). Group 2 (1189 N) was not significantly different from Groups 1 and 3. The higher thickness of Clearfil SE Bond was obtained in the concave part of the preparation. Protect Liner F presented a more uniform range of values at different positions. The thickness of Panavia F was higher in the occlusal portion of the preparation. Conclusions: The film thickness formed by the IDS materials is influenced by the position under the crown, suggesting its potential to increase the fracture load of the IPS empress 2 ceramic crowns.

Aim To determine whether the use of oval posts increases fracture resistance of root canal treated teeth with oval-shaped canals. Methods Extracted mandibular premolars with similar dimensions were decoronated. After root canal treatment, standardized post space preparations were performed to simulate the presence of oval-shaped root canal morphologies. Specimens were randomly assigned to 3 groups (n = 3 × 24). In group SFP (small fiber post), circular posts with a cervical diameter of 1.5 mm were used without additional form-congruent post space preparation. In group LFP (large fiber post), a circular post space preparation was performed to adapt posts with a cervical diameter of 1.9 mm. In group OFP (oval fiber post), oval posts with a long cervical diameter of 1.9 mm and short cervical diameter of 1.3 mm were utilized without additional post space preparation. Posts were cemented with dual-cure resin. All specimens were restored with standardized direct composite crowns. After thermo-mechanical loading in a computer-controlled masticator, all specimens underwent fracture resistance testing. Means and standard deviations were calculated. Data were analyzed using the Kruskal–Wallis test (α = 0.05). Results The highest mean fracture load was observed in group OFP (273N ± 51), the lowest in group LFP (258N ± 72). Kruskal–Wallis indicated no significant differences in fracture resistance among the three experimental groups. Conclusions Within the limitations of this laboratory study, oval posts did not reveal increased fracture resistance of root canal-treated premolars with oval-shaped root canals compared with circular posts.

A set of mixed-mode I/II fracture tests was carried out on a polyurethane material. Using a single edge notched bend (SENB) type specimen, containing straight and respectively inclined U notches, the full range from pure mode I to dominant mode II was achieved. Two different fracture criteria were employed for the prediction of the fracture conditions: the UMTS criterion and the averaged SED criterion. Using these two criteria a set of curves were derived in terms of the fracture load vs. notch radius. The agreement between the experimental results and those predicted based on these two criteria is discussed finally.

The tensile strength of a tablet is an important attribute as the tablet needs to be mechanically strong enough to withstand further handling such as film–coating, packaging, transport and end-use by the patient, but to be weak enough to break apart in the human body and so release its contents. Mathematical solutions to calculate tensile strength are known for flat-faced and convex-faced circular tablets. The work described here aims to extend this knowledge to capsule-shaped and oval-shaped tablets by means of 2-dimensional (2D) and 3-dimensional (3D) Finite Element Analysis (FEA). The stress analysis showed that as the tablet was elongated from a standard circular tablet to become that of an extended tablet shape, the peak principal tensile stress reached a limiting value. This limiting value was reached as the ratio of the length to width dimensions exceeded 1.7:1, which encompasses most modern pharmaceutical tablets. In addition the stress analysis shows that this limiting value approximated to 2/3 that calculated for circular tablets. Hence for a convex-faced elongated tablet the calculation for tensile strength generated by Pitt et al. [1] would become: σ t = 2 3 10 P π D 2 2.84 t D − 0.126 t W + 3.15 W D + 0.01 where σt is the tensile strength, P is the fracture load, D is the length of the short axis, t is the overall thickness and W is the wall height of the tablet, as shown in Fig. 1c. The solution was then checked by applying it to commercial tablets of differing shapes to demonstrate its utility.

This paper presents an experimental and analytical study into the strengthening and toughening of sandwich composite joints by z-pinning. Cleats connecting the vertical stiffener and horizontal base panel to T-shaped sandwich joints were reinforced in the through-thickness direction with pins. Tensile (stiffener pull-off) tests revealed that pinning increased the ultimate fracture load and fracture energy by resisting crack growth along the cleat–skin and skin–core interfaces, which were the weakest points in the unpinned joint. The peak fracture load and fracture energy increased with the volume content of z-pins. The strengthening and toughening effect of the pins was analysed using multiple pin pull-out tests performed on the sandwich composite material. It is shown that elastic deformation, debonding and pull-out of the pins from the face skins to the sandwich composite is the primary toughening mechanism of the pinned T-joints. The pin pull-out process, which is the cause for the high strengthening and toughening of the T-joints, is analysed using bridging traction modelling.

OBJECTIVES To evaluate marginal adaptation, fracture load and failure types of CAD/CAM polymeric inlays. METHODS Standardized prepared human molars (48) were divided into four groups (n=12): (A) PCG (positive control group); adhesively luted glass-ceramic inlays, (B) TRX; CAD/CAM polymeric inlays luted using a self-adhesive resin cement, (C) TAC; CAD/CAM polymeric inlays luted using a conventional resin cement, and (D) NCG (negative control group); direct-filled resin-based composite restorations. All specimens were subjected to a chewing simulator. Before and after chewing fatigue, marginal adaptation was assessed at two interfaces: (1) between dental hard tissues and luting cement and (2) between luting cement and restoration. Thereafter, the specimens were loaded and the fracture loads, as well as the failure types, were determined. The data were analysed using three- and one-way ANOVA with post hoc Scheffe test, two sample Student's t-test (p

Wire rope in elevators can become disconnected by tensile stress from friction between the rope and sheave, and by repeated stress including bending stress from various effects formed during contact between the rope and sheave. It is known that in designing wire rope, its strength is affected when wire disconnection occurs. However, insufficient related data is available. Therefore, fracture strength reduction and the effect of bending fatigue on wire rope life is difficult to evaluate. We considered the effects of wire rope diameter and tensile stress on fracture strength and wire rope life. We observed that fracture strength rapidly decreased when bending fatigue accumulated at the same time that the wire became disconnected. Moreover, bending fatigue was shown to be a crucial factor in decreased wire rope life.

The paper deals with the minimum value of a fracture load, with respect to the notch root radius, in plates weakened by U-notches under Mode I loading. It has been found that the fracture load has a minimum value at a critical value of the notch root radius ( ρ ), using four criteria, namely, Mean Stress (MS), maximum tangent stress or Point Stress (PS), Critical Strain-Energy (CSE) and Averaged Strain-Energy Density (ASED). Using a characteristic length ( l c h ), which is a function of material properties, the results showed that the dimensionless critical notch root radius ( ρ / l c h ) c r depended on w / a ratio (the specimen width to the notch depth), Poisson ratio, and loading condition (tensile or bending loading) under Mode I loading. In other words, according to these criteria, a notch root radius different from zero exists, providing a minimum fracture load. Therefore, a crack is not more dangerous rather than a U-notch under Mode I loading. This critical notch root radius is important for a quasi-brittle material, but may not be significant for brittle ones in practical engineering situations. Good agreement was found between theoretical predictions and experimental results on Al356-T6.

International audience; Twenty-one excised femurs were studied using (1) a high-resolution digital X-ray device to estimate three textural parameters, (2) dual-energy X-ray absorptiometry (DXA) to measure bone mineral density (BMD), and (3) mechanical tests to failure. Textural parameters significantly correlated with BMD (p < 0.05) and bone strength (p < 0.05). Combining texture parameters and BMD significantly improved the fracture load prediction from adjusted r (2) = 0.74 to adjusted r (2) = 0.82 (p < 0.05). Introduction The purpose of this study is to determine if the combination of bone texture parameters using a new high-resolution X-ray device and BMD measurement by DXA provided a better prediction of femoral failure load than BMD evaluation alone. Methods The proximal ends of 21 excised femurs were studied using (1) a high-resolution digital X-ray device (BMA (TM), D3A Medical Systems) to estimate three textural parameters: fractal parameter Hmean, co-occurrence, and run-length matrices, (2) DXA to measure BMD, and (3) mechanical tests to failure in a side-impact configuration. Regions of interest in the femoral neck, intertrochanteric region, and greater trochanter were selected for DXA and bone texture analysis. Every specimen was scanned twice with repositioning before mechanical testing to assess reproducibility using intraclass correlation coefficient (ICC) with 95% confidence interval. The prediction of femoral failure load was evaluated using multiple regression analysis. Results Thirteen femoral neck and 8 intertrochanteric fractures were observed with a mean failure load of 2,612 N (SD, 1,382 N). Fractal parameter Hmean, co-occurrence, and run-length matrices each significantly correlated with site-matched BMD (p < 0.05) and bone strength (p < 0.05). The ICC of the textural parameters varied between 0.65 and 0.90. Combining bone texture parameters and BMD significantly improved the fracture load prediction from adjusted r (2) = 0.74 to adjusted r (2) = 0.82 (p < 0.05). Conclusion In these excised femurs, the combination of bone texture parameters with BMD demonstrated a better performance in the failure load prediction than that of BMD alone.

Purpose: This study evaluated the load bearing capacity of anatomically designed canines restored with FRC posts and experimental short fiber composite resin (FC). The effect of using three different types of tooth preparation and woven net on the fracture load was also investigated. Further aim was to evaluate the failure mode of each restoration. Material and methods: 80 maxillary frasaco-canines were divided into 10 groups (n=8). The anatomic crowns were cut perpendicular at CEJ of the tooth. Group 1 was composed of teeth with flattened surface. Groups 2, 3 & 4 were prepared of teeth with 2 mm ferrule. In the third group, everStick Net was applied above the ferrule. Group 5 was composed of teeth with large box type preparation. The root canals were enlarged, sandblasted and then surface treated with Stick resin for 5 min. Two types of FRC root canal posts were used. The crowns were prepared either with composite resin or with FC. A static load until failure was applied to the crowns at a 45 degrees angle. Failure modes were visually examined. Results: ANOVA revealed that use of FRC-post and tooth preparation (p0.001). Chi-square test revealed that both, crown design and existence of FRC-post effected significantly fracture types (p

Eight pairs of fresh frozen human femora were prepared for hip resurfacing. One side of each pair was impacted gently, the other side vigorously. After implantation procedure, specimens were loaded in a material testing machine to the ultimate fracture load. Median impaction loads on the vigorously implanted side were 11,298N compared to 1374N on the gently implanted side. Failure loads in the high-impact group (median, 8873N) were significantly (P = .0078) reduced when compared with the low-impact group (median, 9237N). The study stresses that meticulous reaming of the femoral head and the pinhole is of tremendous importance. Remaining obstacles can lead to excessive loads, while attempting to enforce the correct seating of the implant. Only careful, slight tapping should be applied to ensure final seating.

The purpose of this study was to evaluate the fracture loads of post-and-core systems with two different individually formed fibre post designs and polymerization conditions.Totally seventy-two (n=8/group) bovine teeth were cut and made up the root length of 15.0mm. They were divided into 3 main groups (Group A, B, C). A: one glass fibre post was light-cured before cementation, B: fibres were bundled to fill the entire root canal opening and light-cured before cementation, C: one unpolymerized glass fibre post was inserted into cement-filled root canal and light-cured with luting cement (ParaCem). Moreover specimens of each group were divided into 3 subgroups according to the post length: subgroup 1: 10mm; subgroup 2: 7.5mm; subgroup 3: 5.0mm. After cementation, the core was built up, and then made the composite resin crown (Filtek Z250). Fabricated specimen was loaded from 45° of palatal side at a crosshead speed of 1.0mm/min. The first load drop and maximum fracture loads were statistically analyzed by ANOVA and Tukey's test.Maximum fracture load of Group B (433 N) and C (418 N) are significantly higher than Group A (284 N) (p0.01). Short post (5mm) provided higher fracture loads in all main groups, especially in Group C.Using short and thick fibre post system (the same diameter as the root canal) showed higher strength than one fibre post only. In addition, by curing the cement and the fibre material simultaneously, the strength of the restored tooth was increased.

The purpose of this study is to propose the design method of mechanical clinching tools, which is used to join aluminium alloy sheets in automobiles. Based on the analytical model used to predict the strength of the mechanical clinched joint, the design method of clinching tools that can satisfy the required joint strength is proposed. The analytical model has been defined as a function of the neck-thickness and the undercut, which are the presented mechanical clinched joint geometry. And joint geometry is defined by the shape parameters of the clinching tools. To obtain the desired joint strength, the required neck-thickness and undercut are inversely calculated from the analytical model. The mechanical clinching tools that join Al6063 alloy sheets are designed by the proposed method. FE-analysis and mechanical clinching test were performed for optimal conditions obtained from the proposed design method. The result of the FE-analysis and that of the mechanical clinching test showed good agreement of the clinched joint geometry. The H-type tensile test for mechanical clinched joint was carried out to evaluate the strength of the mechanical clinched joint designed by the proposed design method. The result of the tensile test showed that the fracture load satisfied the required joint strength. Also, the top-hat impact test was performed to evaluate the feasibility of using mechanical clinching for automotive component assembly. The result of impact test showed that mechanical clinching was able to produce similar crash resistance as self-piercing riveting.