Light chain mutations contribute to defining the fibril morphology in systemic AL amyloidosis.

Systemic AL amyloidosis is one of the most frequently diagnosed forms of systemic amyloidosis. It arises from mutational changes in immunoglobulin light chains. To explore whether these mutations may affect the structure of the formed fibrils, we determine and compare the fibril structures from several patients with cardiac AL amyloidosis. All patients are affected by light chains that contain an IGLV3-19 gene segment, and the deposited fibrils differ by the mutations within this common germ line background. Using cryo-electron microscopy, we here find different fibril structures in each patient. These data establish that the mutations of amyloidogenic light chains contribute to defining the fibril architecture and hence the structure of the pathogenic agent.

Insights into the Structural Basis of Amyloid Resistance Provided by Cryo-EM Structures of AApoAII Amyloid Fibrils.

Amyloid resistance is the inability or the reduced susceptibility of an organism to develop amyloidosis. In this study we have analysed the molecular basis of the resistance to systemic AApoAII amyloidosis, which arises from the formation of amyloid fibrils from apolipoprotein A-II (ApoA-II). The disease affects humans and animals, including SAMR1C mice that express the C allele of ApoA-II protein, whereas other mouse strains are resistant to development of amyloidosis due to the expression of other ApoA-II alleles, such as ApoA-IIF. Using cryo-electron microscopy, molecular dynamics simulations and other methods, we have determined the structures of pathogenic AApoAII amyloid fibrils from SAMR1C mice and analysed the structural effects of ApoA-IIF-specific mutational changes. Our data show that these changes render ApoA-IIF incompatible with the specific fibril morphologies, with which ApoA-II protein can become pathogenic in vivo.

Cryo-EM Analysis of the Effect of Seeding with Brain-derived Aß Amyloid Fibrils.

Aß amyloid fibrils from Alzheimer's brain tissue are polymorphic and structurally different from typical in vitro formed Aß fibrils. Here, we show that brain-derived (ex vivo) fibril structures can be proliferated by seeding in vitro. The proliferation reaction is only efficient for one of the three abundant ex vivo Aß fibril morphologies, which consists of two peptide stacks, while the inefficiently proliferated fibril morphologies contain four or six peptide stacks. In addition to the seeded fibril structures, we find that de novo nucleated fibril structures can emerge in seeded samples if the seeding reaction is continued over multiple generations. These data imply a competition between de novo nucleation and seed extension and suggest further that seeding favours the outgrowth of fibril morphologies that contain fewer peptide stacks.

Amyloid fibril structure from the vascular variant of systemic AA amyloidosis.

Systemic AA amyloidosis is a debilitating protein misfolding disease in humans and animals. In humans, it occurs in two variants that are called 'vascular' and 'glomerular', depending on the main amyloid deposition site in the kidneys. Using cryo electron microscopy, we here show the amyloid fibril structure underlying the vascular disease variant. Fibrils purified from the tissue of such patients are mainly left-hand twisted and contain two non-equal stacks of fibril proteins. They contrast in these properties to the fibrils from the glomerular disease variant which are right-hand twisted and consist of two structurally equal stacks of fibril proteins. Our data demonstrate that the different disease variants in systemic AA amyloidosis are associated with different fibril morphologies.

Cryo-EM demonstrates the in vitro proliferation of an ex vivo amyloid fibril morphology by seeding.

Several studies showed that seeding of solutions of monomeric fibril proteins with ex vivo amyloid fibrils accelerated the kinetics of fibril formation in vitro but did not necessarily replicate the seed structure. In this research we use cryo-electron microscopy and other methods to analyze the ability of serum amyloid A (SAA)1.1-derived amyloid fibrils, purified from systemic AA amyloidosis tissue, to seed solutions of recombinant SAA1.1 protein. We show that 98% of the seeded fibrils remodel the full fibril structure of the main ex vivo fibril morphology, which we used for seeding, while they are notably different from unseeded in vitro fibrils. The seeded fibrils show a similar proteinase K resistance as ex vivo fibrils and are substantially more stable to proteolytic digestion than unseeded in vitro fibrils. Our data support the view that the fibril morphology contributes to determining proteolytic stability and that pathogenic amyloid fibrils arise from proteolytic selection.

Protease resistance of ex vivo amyloid fibrils implies the proteolytic selection of disease-associated fibril morphologies.

Several studies recently showed that ex vivo fibrils from patient or animal tissue were structurally different from in vitro formed fibrils from the same polypeptide chain. Analysis of serum amyloid A (SAA) and Aß-derived amyloid fibrils additionally revealed that ex vivo fibrils were more protease stable than in vitro fibrils. These observations gave rise to the proteolytic selection hypothesis that suggested that disease-associated amyloid fibrils were selected inside the body by their ability to resist endogenous clearance mechanisms. We here show, for more than twenty different fibril samples, that ex vivo fibrils are more protease stable than in vitro fibrils. These data support the idea of a proteolytic selection of pathogenic amyloid fibril morphologies and help to explain why only few amino acid sequences lead to amyloid diseases, although many, if not all, polypeptide chains can form amyloid fibrils in vitro.

Anesthesiologists' airway management expertise: Identifying subjective and objective knowledge gaps.

BACKGROUND: Failure in airway management continues to cause preventable patient harm, and the recommended continuing education is challenged by anesthesiologists' unknown knowledge gaps. This study aimed to identify anesthesiologists' subjective and objective knowledge gaps as well as areas where anesthesiologists are incorrect and unaware. METHODS: An adaptive E-learning program with 103 questions on adult airway management was used for subjective and objective assessment of anesthesiologists' knowledge. All anesthesiologists in the Capital Region of Denmark were invited to participate. RESULTS: The response rate was 67% (191/285). For preoperative planning, participants stated low confidence (subjective assessment) regarding predictors of difficult airway management in particular (69.1%-79.1%). Test scores (objective assessment) were lowest for obstructive sleep apnea as a predictor of difficult airway management (28.8% correct), with participants being incorrect and unaware in 33.5% of the answers. For optimization of basic techniques, the lowest confidence ratings related to patient positioning and prediction of difficulties (57.4%-83.2%), which agreed with the lowest test scores. Concerning advanced techniques, videolaryngoscopy prompted the lowest confidence (72.4%-85.9%), while emergency cricothyrotomy resulted in the lowest test scores (47.4%-67.8%). Subjective and objective assessments correlated and lower confidence was associated with lower test scores: preoperative planning [r = -.58, P < .001], optimization of basic techniques [r = -.58, P = .002], and advanced techniques [r = -.71, P < .001]. CONCLUSION: We identified knowledge gaps in important areas of adult airway management with differing findings from the subjective and objective assessments. This underlines the importance of objective assessment to guide continuing education.

[Advanced life support for cardiac arrest beyond the algorithm].

In an advanced emergency medical service all parts of the advanced life support (ALS) algorithm can be provided. This evidence-based algorithm outlines resuscitative efforts for the first 10-15 minutes after cardiac arrest, whereafter the algorithm repeats itself. Restoration of spontaneous circulation fails in most cases, but in some circumstances the patient may benefit from additional interventional approaches, in which case transport to hospital with ongoing cardiopulmonary resuscitation is indicated. This paper has summarized treatments outside the ALS algorithm, which may be beneficial, but are not supported by firm scientific evidence.

Cleaning effectiveness of implant prophylaxis instruments.

PURPOSE: The aim of this study was to evaluate the cleaning effectiveness of implant prophylaxis instruments on polished and acid-etched implant surfaces. MATERIALS AND METHODS: Biofilm layers of Streptococcus mutans were grown on a total of 80 titanium disks; 40 disks were polished and 40 were acid-etched. Five disks of each surface were cleaned using each of seven implant prophylaxis instruments: (1) manual plastic curette, (2) manual carbon fiber-reinforced plastic (CFRP) curette, (3) sonic-driven prophylaxis brush, (4) rotating rubber cup with prophylaxis paste, (5) sonic-driven polyether ether ketone (PEEK) plastic tip, (6) ultrasonic-driven PEEK plastic tip, and (7) air polishing with amino acid (glycine) powder. Ten disks (five of each surface type) served as controls. After cleaning, the surfaces with remaining bacteria were assessed by light microscopy. Statistical analyses of the results were performed with one-way and two-way analyses of variance with Bonferroni-Dunn multiple comparisons post hoc analysis (α = .05). RESULTS: The cleaning effectiveness of the plastic curette was significantly lower than those of all machine-driven instruments on the polished surface. Significantly lower cleaning effectiveness occurred with the CFRP curette compared to the prophylaxis brush and to both oscillating PEEK plastic tips on the polished surface. The rubber cup provided less cleaning effectiveness compared to the ultrasonic PEEK plastic tip and air polishing on the acid-etched surface. Superior results, with less than 4% of the biofilm remaining, were obtained for both oscillating PEEK plastic tips and air polishing on both implant surfaces. The cleaning ability of the prophylaxis brush, rubber cup, and ultrasonic PEEK plastic tip differed significantly between both surface structures. CONCLUSIONS: Cleaning effectiveness, ie, less than 4% of the biofilm remaining, was not observed with all tested implant prophylaxis instruments. The cleaning ability of the devices depended on the implant surface structure.

Properties of Halococcus salifodinae, an Isolate from Permian Rock Salt Deposits, Compared with Halococci from Surface Waters.

Halococcus salifodinae BIpT DSM 8989T, an extremely halophilic archaeal isolate from an Austrian salt deposit (Bad Ischl), whose origin was dated to the Permian period, was described in 1994. Subsequently, several strains of the species have been isolated, some from similar but geographically separated salt deposits. Hcc. salifodinae may be regarded as one of the most ancient culturable species which existed already about 250 million years ago. Since its habitat probably did not change during this long period, its properties were presumably not subjected to the needs of mutational adaptation. Hcc. salifodinae and other isolates from ancient deposits would be suitable candidates for testing hypotheses on prokaryotic evolution, such as the molecular clock concept, or the net-like history of genome evolution. A comparison of available taxonomic characteristics from strains of Hcc. salifodinae and other Halococcus species, most of them originating from surface waters, is presented. The cell wall polymer of Hcc. salifodinae was examined and found to be a heteropolysaccharide, similar to that of Hcc. morrhuae. Polyhydroxyalkanoate granules were present in Hcc. salifodinae, suggesting a possible lateral gene transfer before Permian times.

Effects of 10 cleaning instruments on four different implant surfaces.

PURPOSE: The aim of this study was to evaluate the effects of a variety of implant cleaning instruments on different implant surfaces, specifically surface roughness and cleaning efficacy. MATERIALS AND METHODS: Biofilm layers of Streptococcus mutans were cultivated on titanium disks with four different surface structures (polished, grit-blasted, acid-etched, and acid-etched/grit-blasted). Five disks each were cleaned using nine mechanical implant cleaning instruments or an erbium:yttrium-aluminum-garnet laser. Surface roughness (average, Ra; maximum, Rz) and waviness (Lr) were evaluated by two-dimensional laser profilometry. Surface structure damage and cleaning scores were assessed by scanning electron microscopy. Statistical analyses of the results were performed with one- and two-way analyses of variance and Bonferroni-Dunn multiple-comparison post hoc analysis (α = .05). RESULTS: Ra and Rz values for the acid-etched surfaces and Ra, Rz, and Lr values for the polished and the grit-blasted surfaces showed no significant differences between the different cleaning methods or cleaning instruments compared to the control (not cultured, not cleaned) groups. Significantly lower Ra and Rz values on grit-blasted/acid-etched implant surfaces were found following use of the Sonic-Flex clean with prophylaxis brush and the plastic curette compared to Satelec ProphyMax with Periosoft curette. Ra and Rz values of the different implant structure surfaces before cleaning were significantly different between all implant surfaces except for the polished compared to the acid-etched surfaces. CONCLUSIONS: Cleaning effect and alterations of the implant surfaces were strongly dependent on the implant cleaning method used.

The effect of changes in head position on enlargement of structures during panoramic radiography.

PURPOSE: Accuracy of panoramic radiographs is essential for distance measurements during implant planning, but it might be compromised by various factors. The aim of the present study was to evaluate the effect of vertical and horizontal head positioning on area-dependent enlargement ratios of digital panoramic radiography. MATERIALS AND METHODS: The mandible of a dry skull was marked with small steel globes. The skull was moved 1 to 4 degrees in 1-degree increments to the left and right and up and down. A series of 17 panoramic radiographs was obtained with the same digital radiographic device. For the rotated skull, horizontal and vertical distances, indicated by the steel globes, were compared to the distances with the ideal positioning of the skull. The results were analyzed statistically. RESULTS: Head positioning and angulation, anatomical site, and distance orientation influenced horizontal measurements. Enlargement ratios of horizontal distances of the right canine and first molar regions (skull rotation to the right 2 to 4 degrees) were significantly lower than those for the corresponding anatomical sites on the left side. Horizontal distance measurements of the different anatomical sites of the left and the right jaw did not differ significantly from each other when the skull was moved downward. When the skull was rotated upward, no significant differences were obtained for corresponding anatomical sites of the right and left arches. Enlargement ratios of vertical distances of different anatomical sites, as well as within the same anatomical site, were not significantly different from each other for the given skull rotations. CONCLUSIONS: Ideal head positioning for digital panoramic radiographs is mandatory to avoid improper enlargement ratios of horizontal distances, which can be important in implant dentistry.

Resistance against pull-out force of prefabricated coated FRC posts.

PURPOSE: To investigate the effect of a prefabricated tribochemical coating of FRC (fiber-reinforced composite) posts with and without aging on the pull-out forces compared to posts without conditioning. MATERIALS AND METHODS: Post space preparations were performed on 108 extracted anterior teeth. Thirty-six uncoated FRC posts (DentinPost) and 72 prefabricated tribochemically coated FRC posts (DentinPost Coated) were used at a length of 12 mm. Thirty-six of the coated posts were thermally aged. FRC posts (n = 9) were placed using DentinBuild or MultiCore Flow foundation composite resins or Panavia F2.0 or RelyX Unicem resin cements. Following water storage (37°, 24 h) and thermocycling (5000 cycles, 5° to 55°C, 30 s), pull-out force testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 3-way ANOVA, Bonferroni-Dunn correction, α = 0.05). RESULTS: Significantly higher pull-out forces of posts luted with Panavia F2.0 were observed for the coated and coated/aged FRC posts compared to the unconditioned posts (control group, p < 0.001). The pull-out forces of tribochemically coated FRC posts luted with MultiCore Flow were significantly lower than of coated posts luted with Panavia F2.0 (p < 0.001). Coated/aged FRC posts exhibited similar pull-out forces for the tested luting composite resins (p > 0.05). Except for DentinBuild (coated posts), more mixed or cohesive fractures were assessed for coated and coated/aged FRC posts than for unconditioned FRC posts. CONCLUSION: Prefabricated tribochemical coating of FRC posts provided a stable interface between coating and post and remained stable over time.

Accumulation of antioxidants in apricot fruit through ripening: characterization of a genotype with enhanced functional properties.

Two apricot genotypes, 'Gonci magyarkajszi' and 'Preventa' were assayed at three ripening stages for flesh color indices (L*, a*, b*, C* and Hº), contents of total phenolics and vitamin C, and both water- and lipid-soluble antioxidant capacities (ferric reducing antioxidant power; 2,2'-diphenyl-1-picrylhydrazyl scavenging activity; total radical scavenging activity; and Photochem lipid-soluble antioxidant capacity) to compare their dynamics in the accumulation of antioxidant compounds and capacities through ripening. The increase in a*, b* and C* and decrease in Hº during ripening represented a color shift from green to yellow and orange due to carotenoid accumulation. Parallel to carotenoid accumulation, contents of total phenolics and vitamin C and antioxidant capacity increased significantly (p < 0.05) from unripe to fully ripe fruits. More phenolics and vitamin C accumulated in fully ripe fruits of 'Preventa' than 'Gönci magyarkajszi'. The accumulation patterns of these compounds were different: while the vitamin C contents in unripe fruit of 'Preventa' and 'Gönci magyarkajszi' were identical (approx. 6 mg/100 g fresh weight), unripe 'Preventa' contained even more phenolics (approx. 12 mmolGA/l) than fully ripe 'Gönci magyarkajszi' (8 mmolGA/l). Our results confirm that fully ripe 'Preventa' fruits are characterized by outstanding functional properties due to the increased accumulation of vitamin C and phenolics throughout the ripening process.

Accumulation of Antioxidants in Apricot Fruit through Ripening: Characterization of a Genotype with Enhanced Functional Properties

Two apricot genotypes, 'Gonci magyarkajszi' and 'Preventa' were assayed at three ripening stages for flesh color indices (L*, a*, b*, C* and Hº), contents of total phenolics and vitamin C, and both water- and lipid-soluble antioxidant capacities (ferric reducing antioxidant power; 2,2'-diphenyl-1-picrylhydrazyl scavenging activity; total radical scavenging activity; and Photochem lipid-soluble antioxidant capacity) to compare their dynamics in the accumulation of antioxidant compounds and capacities through ripening. The increase in a*, b* and C* and decrease in Hº during ripening represented a color shift from green to yellow and orange due to carotenoid accumulation. Parallel to carotenoid accumulation, contents of total phenolics and vitamin C and antioxidant capacity increased significantly (p < 0.05) from unripe to fully ripe fruits. More phenolics and vitamin C accumulated in fully ripe fruits of 'Preventa' than 'Gonci magyarkajszi'. The accumulation patterns of these compounds were different: while the vitamin C contents in unripe fruit of 'Preventa' and 'Gonci magyarkajszi' were identical (approx. 6 mg/100 g fresh weight), unripe 'Preventa' contained even more phenolics (approx. 12 mmolGA/l) than fully ripe 'Gonci magyarkajszi' (8 mmolGA/l). Our results confirm that fully ripe 'Preventa' fruits are characterized by outstanding functional properties due to the increased accumulation of vitamin C and phenolics throughout the ripening process.

Effect of surface conditioning on the retentive bond strengths of fiberreinforced composite posts.

STATEMENT OF PROBLEM: Debonding is a common cause of failure encountered with fiber-reinforced composite (FRC) posts, and usually occurs along the post space-dentin adhesive interface. Surface conditioning of posts is expected to increase the chemical and mechanical bond between the luting composite resin and the post, but the best method has not been definitively determined. PURPOSE: The purpose of this in vitro study was to compare the effects of 3 surface-conditioning methods on the retentive bond strengths of FRC posts using 5 composite resin materials, and compare results to those of unconditioned FRC posts as well. MATERIAL AND METHODS: Post space preparations (DentinPost ER root post system, length of 12 mm) were performed on 200 human anterior teeth. Groups of 50 FRC posts (ISO size 90) each were treated using 1 of the following conditioning methods: silanization, etching with 5% hydrofluoric acid, tribochemical coating (CoJet system), or were left untreated (control group). FRC posts (n=10) in each group were placed using 1 of 5 composite resin materials (Calibra or RelyX Unicem resin cements or Build-It, MultiCore Flow, or Rebilda DC foundation composite resins). Following water storage (37 degrees C, 24 hours) and thermal cycling (5000 cycles, 5 degrees -55 degrees C, 30-second dwell time), tensile strength testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 2-way ANOVA, Bonferroni-Dunn correction, alpha=.05). RESULTS: Retentive bond strengths of FRC posts luted with MultiCore Flow in combination with the CoJet system, and of posts inserted with Rebilda DC in combination with hydrofluoric acid (HF) etching as well as with the CoJet system, were significantly higher than those of the corresponding unconditioned FRC posts (P<.001). No significant differences were noted between the bond strength values of RelyX Unicem with CoJet, MultiCore Flow with CoJet, and Rebilda DC with either CoJet or HF etching (P>.05). Retentive bond strengths were significantly lower for HF etching (Calibra, RelyX Unicem, Build-It), and for the treatment with the CoJet system in combination with Build-It compared to the corresponding control groups (P<.001). Fracture modes were primarily adhesive at the post surface or cohesive within the composite resin layer or within the FRC post. CONCLUSIONS: The retentive bond strengths differed significantly with respect to the tested combinations of conditioning method and luting composite resin.

Clinical evaluation of ceramic inlays compared to composite restorations.

This study compared the clinical performance of indirectly manufactured ceramic Evopress inlays with those of directly placed, fine particle hybrid Filtek Z250 composite restorations in posterior teeth. From January 2000 to October 2003, 109 patients received 264 Evopress (Wegold) ceramic inlays and 68 patients received 145 Filtek Z250 (3M ESPE) composite restorations in a dental office. Two-hundred and fifty ceramic inlays (95%) and 135 composite restorations (93%) were re-examined up to 57 months after placement. Modified USPHS criteria were used for the study. The worst finding of all the assessments was the overall assessment of individual restorations. On the basis of these criteria, 220 (88%) Evopress ceramic inlays were assessed as Alpha at the time of clinical re-examination, 26 (10%) were judged Beta and four ceramic inlays (2%) were rated Delta in the re-examination interval and thus categorized as failures. At the time of re-examination, 91 of the 135 composite restorations (67%) were judged Alpha, 36 restorations (26%) were rated Beta and three restorations (2%) were judged Charlie. Five restorations (4%) were categorized as failures (Delta). In two cases, there were marginal gap formations; there were also two cases of secondary caries after 28 and 35 months, as well as a fracture after 13 months. According to Kaplan and Meier, the survival rate after 57 months was 94% for ceramic inlays and 93% for composite restorations. The log rank test showed no significant differences in the survival curves. The current study showed that indirectly manufactured Evopress ceramic inlays performed better than direct Filtek Z250 composite restorations in marginal adaptation, color match and anatomic form. However, with regard to survival probability, there was no significant difference.

Yield strength of fiber-reinforced composite posts with coronal retention.

STATEMENT OF PROBLEM: Currently, glass fiber-reinforced composite (FRC) posts with shank heads are only recommended for moderate coronal defects. Restoring endodontically treated teeth with large coronal defects remains a challenge, requiring posts with coronal retention and high bending resistance. PURPOSE: The purpose of this in vitro study was to investigate the yield strengths of FRC posts and titanium posts (TI) with coronal retention for core foundations compared to FRC and TI posts without coronal retention. MATERIAL AND METHODS: Tapered posts (ER root post system) of 4 diameters (ISO 50, 70, 90, 110), 2 lengths (tapered part: 9 and 12 mm) of identical shape, 2 materials (FRC, titanium), and 2 head designs (shank without retention (SH) and post head with horizontal retention (RET)) were evaluated (n=9). Titanium posts (TI-SH, TI-RET) served as the control. The 0.2% yield strengths (R(0.2)) of all specimens were tested in a universal testing machine. Three-way and 1-way ANOVAs with Bonferroni-Dunn's multiple comparison tests were performed (alpha=.05). RESULTS: The yield strengths of the control groups TI-RET were significantly higher for ISO 110 with a 9-mm length and for ISO 70 and 110 with a 12-mm length, compared to the respective FRC-RET posts (P<.001), whereas in all other groups, TI-RET and FRC-RET showed no significant differences. FRC-SH groups did not differ from FRC-RET groups. TI-SH showed significantly lower yield strength for ISO 70 compared to TI-RET, but significantly higher values for ISO 90 and 110 (P<.001). CONCLUSIONS: Head design of the tested FRC posts does not improve the yield strength, compared to FRC posts with a shank design. The diameter of the posts had a significant effect on the yield strengths of RET as well as SH groups.

Influence of oversized dowel space preparation on the bond strengths of FRC posts.

This study compared the bond strengths of fiber-reinforced composite (FRC) posts luted into oversized dowel spaces with FRC posts luted into precisely fitting dowel spaces using five different resin cements or build-up composites. The hypotheses examined were that bond strength does not present vast variations according to the width of the gap between the root canal and post and that bond strength increases for FRC posts luted with build-up composites compared with FRC posts luted with resin cements. Dowel space preparations (ER post-restoring system, 12 mm in length) were performed on 100 human anterior teeth up to ISO 90 and ISO 110 of 50 roots each. FRC posts, all ISO size 90, were inserted into the precisely fitting as well as into the oversized dowel spaces (n = 10) using five composite materials (Calibra, Multicore Flow, Rely X Unicem; resin cements and Build-It, Rebilda DC; build-up composites). The manufacturers' instructions of the composite materials were strictly followed except for Rebilda DC, which was used with Adhese for dentin bonding. Following water storage (37 degrees C, 24 hours) and thermocycling (5000 cycles, 5 degrees C-55 degrees C, 30 seconds) tensile strength testing was performed and fracture modes were assessed using SEM. Data were analyzed statistically (one-way and two-way ANOVA, Bonferroni/Dunn correction, alpha < 0.05). The retentive bond strengths of FRC posts in oversized dowel spaces decreased significantly for all luting composites except for Rebilda DC, compared with the respective groups with precise fitting (p < 0.011). Yet, the bond strengths of RelyX Unicem (454 N +/- 64 N), Build-It (422 N +/- 43 N) and Calibra (408 N +/- 50 N) showed significantly higher values for the precisely fitting posts than Rebilda DC (267 N +/- 54 N). RelyX Unicem revealed significantly higher values than Multicore Flow (296 N +/- 73 N). The bond strengths of FRC posts in oversized dowel spaces varied from 301 N +/- 78 N for Build-It to 152 N +/- 37 N for Calibra. The values of Build-It were significantly higher compared with Calibra, Multicore Flow (180 N +/- 47 N) and Rebilda DC (186 N +/- 52 N), as well as those of RelyX Unicem (256 N +/- 115 N) were significantly higher than Calibra. Fracture modes were shown to be mainly adhesive at the post surface or cohesive for precisely fitting posts and to occur between post and composite except for RelyX Unicem with cohesive fractures for the oversized dowel spaces. The build-up composite Build-It showed superior bond strengths in oversized canals, which were still not as high as those of posts in precisely fitting dowel spaces using common resin cements.