This study investigated the flexural strength of 8 fiber posts (one carbon fiber, one carbon/quartz fiber, one opaque quartz fiber, two translucent quartz fiber and three glass fiber posts). Eighty fiber posts were used and divided into 8 groups (n=10): G1- Composipost / C-Post (RTD), G2-Aestheti-Post (RTD), G3-Aestheti-Plus (RTD), G4- Light-Post (RTD), G5- D. T. Light-Post (RTD), G6- ParaPost White (Coltene/Whaledent), G7-FiberKor (Pentron) and G8-Reforpost (Angelus). All of the samples were tested using a three-point bending test. Statistical analysis of the outcomes was conducted by means of analysis of variance and the post factor was significant (p<0.001). The critical value for comparison revealed that G2 (677.4 MPa +/18.3) and G3 (666.2 +/- 18.1) presented the highest flexural strength values. G1 (616.3 +/- 24.8) and G3 presented similar strengths. G1, G4 (607.2 +/- 19.5), G5 (608.7 +/-69.5), G6 (585.2 +/- 24.2) and G7 (562 +/- 59.6) were statistically similar. Reforpost-G8 (433.8 +/- 46.4) revealed the lowest flexural strength value compared to the other groups.

Objectives: To evaluate the flexural modulus and flexural strength of different types of endodontic post in comparison with human root dentin.
Methods: Three different types of fiber-reinforced composite (FRC) posts and three metal posts each comprising 10 specimens (n=10) and 20 dentin bars were loaded to failure in a three-point bending test to determine the flexural modulus (GPa) and the flexural strength (MPa). Three randomly selected fiber posts of each group were evaluated using a scanning electron microscope (SEM) to illustrate the differences in mode of fracture. Data were subjected to a one-way ANOVA to determine significant differences between groups and the Bonferroni t-test multiple comparison was applied to investigate which mean values differed from one another with significance levels of P<0.05.
Results: The flexural modulus recorded for the dentin bars was 17.5+/-3.8GPa. The values for posts ranged from 24.4+/-3.8GPa for silica fiber posts to 108.6+/-10.7GPa for stainless steel posts. The flexural strength for dentin was 212.9+/-41.9MPa, while the posts ranged from 879.1+/-66.2MPa for silica fiber posts to 1545.3+/-135.9MPa for cast gold posts. The ANOVA test analysis revealed significant differences between groups (P<0.05) for flexural modulus and flexural strength mean values.
Significance: FRC posts have an elastic modulus that more closely approaches that of dentin while that for metal posts was much higher. The flexural strength of fiber and metal posts was respectively four and seven times higher than root dentin.

Objectives: The aim of this study was to investigate the ultrastructure and resistance to fracture of eight different types of fiber post, and to verify the existence of a correlation between structural characteristics and flexural strength.
Methods: Eight types of fiber post were selected for this study. Fiber Kor (Jeneric-Pentron), Para Post Fiber White (Coltene), Luscent Anchor (Dentatus), Twin-Luscent Anchor (Dentatus), Style Post (Metalor), DT White-Post (VDW), DT Light-Post (VDW / RTD, St Egreve, France) and ER Dentin Post (Brasseler). Ten posts of each experimental group were selected for a three-point bending test, and one was processed for SEM evaluation. A universal testing machine loading at an angle of 90 degrees was employed for the three-point bending test. The test was carried out until fracturing of the post. After fracture testing, the posts with the highest and the lowest values of flexural strength of each system were additionally processed for SEM analysis. SEM evaluation was performed using a PC-measurement program to assess the fiber/matrix ratio and fiber dimensions.
Results: The fracture load of the tested systems ranged from 60 to 96 N and the flexural strength from 565 to 898 MPa. DT White-Post and DT Light-Post (898 and 842 MPa, respectively) had significantly higher flexural strengths than the other posts. Style Post (565 MPa) showed a significantly lower flexural strength than all other posts. The differences in fiber diameter ranged from 8.2 to 21 micron and for the fiber/matrix ratio from 41 to 76%. Of the various structural characteristics investigated, only the fiber/matrix ratio showed a significant correlation to the flexural strength (r=0.922, p=0.003).
Significance: The FRC-posts investigated displayed significant differences with regard to fracture load and flexural strength. A strong and significant linear correlation between the fiber/matrix ratio and the flexural strength was found.

Objectives: The aim of this study was to investigate the ultrastructure and resistance to fracture of eight different types of fiber post, and to verify the existence of a correlation between structural characteristics and flexural strength.
Methods: Eight types of fiber post were selected for this study. Fiber Kor (Jeneric-Pentron), Para Post Fiber White (Coltene), Luscent Anchor (Dentatus), Twin-Luscent Anchor (Dentatus), Style Post (Metalor), DT White-Post (VDW), DT Light-Post (VDW / RTD, St Egreve, France) and ER Dentin Post (Brasseler). Ten posts of each experimental group were selected for a three-point bending test, and one was processed for SEM evaluation. A universal testing machine loading at an angle of 90 degrees was employed for the three-point bending test. The test was carried out until fracturing of the post. After fracture testing, the posts with the highest and the lowest values of flexural strength of each system were additionally processed for SEM analysis. SEM evaluation was performed using a PC-measurement program to assess the fiber/matrix ratio and fiber dimensions.
Results: The fracture load of the tested systems ranged from 60 to 96 N and the flexural strength from 565 to 898 MPa. DT White-Post and DT Light-Post (898 and 842 MPa, respectively) had significantly higher flexural strengths than the other posts. Style Post (565 MPa) showed a significantly lower flexural strength than all other posts. The differences in fiber diameter ranged from 8.2 to 21 micron and for the fiber/matrix ratio from 41 to 76%. Of the various structural characteristics investigated, only the fiber/matrix ratio showed a significant correlation to the flexural strength (r=0.922, p=0.003).
Significance: The FRC-posts investigated displayed significant differences with regard to fracture load and flexural strength. A strong and significant linear correlation between the fiber/matrix ratio and the flexural strength was found.

Objectives: a) To evaluate the effects of storage time, storage condition, and type of fiber post on the posts fracture strength b) To morphologically evaluate the post structure before and after storage and mechanical stress.
Methods: GC posts (GC Co), DT Light Posts (RTD), and FRC Postec Plus posts (Ivoclar-Vivadent) were divided in different groups (n=14) depending on storage time (1, 6, 12 months), storage condition (air at room temperature, saline water at 37°C, silicon oil at 37°C and inserted inside the roots of extracted canines having the apex sealed by gutta percha; an adhesive restoration was provided coronally, and the samples were immersed in water). All specimens were loaded in a universal testing machine with a compressive load (N) applied at an angle of 45° degrees to the axis of the specimen at a crosshead speed of 1 mm/min until fracture. Fracture loads (N) were recorded. A 3-way ANOVA and Tukey's test (á=.05) were used to compare the effect of the experimental factors on the fracture strength. Two posts of each group were observed before and after the storage and after the mechanical tests using a scanning electron microscope (Joel).
Results: Statistical analysis revealed that type of post, storage time, and storage conditions had a significant effect on the fracture strength (p<0,05). The interaction between these factors was significant (p<0,05). Water storage significantly decreased the mean fracture strength for each type of post regardless of the storage time. Storage inside roots, oil, and air did not significantly affect post fracture strength. SEM micrographs revealed voids and discontinuities between fibers and resin matrix for posts stored in water. Posts stored under the other conditions showed a compact matrix without porosities.
Conclusion: Water storage decreases fiber posts mechanical properties. Fiber posts stored into root canals are not affected by water uptake.

Aim: The aim of the present study was to assess the fatigue resistance of several types of fiber posts by using a 3-point bending test and to observe their ultrastructure through Scanning Electron Microscopy (SEM) before and after undergoing the fatigue test.
Methods: Six types of fiber posts were selected for this study, EasyPost (Group 1), ParaPost Fiber White (Group 2), FiberKor (Group 3), D. T. Light-Post (Group 4), Lucent Anchors (Group 5), and SnowPost (Group 6). Each group contained 15 posts; 5 posts in each group were observed with SEM, the other ten were used for the fatigue test. A three-point bending machine, loading at an angle of 90 degrees and a frequency of 3 Hz, was employed for fatigue testing. The test was carried out until 2 million cycles were completed or until the post fractured. After the fatigue test had been completed, further evaluations were carried out with SEM on the fractured posts and the posts that went to the end of the fatigue cycles.
Results: The fatigue test showed statistically significant differences among the different posts. Group 4 (D.T. Light-Post) performed better than all the other groups, withstanding the entire load cycles without fractures.
Conclusions: There are great variations in the responses of different kinds of fiber posts to a fatigue resistance test. Structural integrity is already very different even before undergoing the fatigue test, and this proves that many of the performance differences noted are due to the differences in the manufacturing processes of the fiber posts.

The lack of radiopacity found with some nonmetallic prefabricated radicular posts in combination with the luting cement can make radiographic interpretation difficult. Objective: This study evaluated the radiographic density of nine cements and eleven posts. Methods: Cements tested were: ZnPO4 (Z) Mizzy; Duolink (DL), Hi-X (HX) Bisco; Ketac Cem (KC); Rely X ARC (RA), Rely X Luting (RL), Rely X Unicem (RU) 3M ESPE; Panavia F (PF) Kuraray; Variolink (V) Ivoclar. Posts tested were: DT Light Post (DT) ; Twin Luscent Anchor (TLA) Dentatus; Parapost XP steel (XP); Parapost XT titanium, (XT); Fiber White (FW), Whaledent; Achromat (A) Axis; Fiberkor (FK) Pentron,; FRC Postec (FRC) Ivoclar. Individual radiographs of each specimen and a continuous aluminum ramp were made using D-speed film (Kodak). These films were scanned and analyzed with NIH Image software. Data were analyzed with a one-way ANOVA and Tukey-Kramer at α=0.05. Results: The mean (sd) density of the cements in terms of equivalent thickness of aluminum were: Z 4.50 (0.45)a, V 3.82 (0.19)b, HX 3.42 (0.27)c, RU 1.57 (0.23)d, RA 1.07 (0.10)e, KC 1.06 (0.17)e, RL 1.02 (0.21)e, DL 0.64 (0.14)f, PF 0.60 (0.24)f. The density of the posts were: XP 11.12 (0.15)a, XT 5.56 (0.18)b, A 1.74 (0.07)c, DT 1.65 (0.12)c, FRC 1.34 (0.12)d, FK 1.05 (0.14)e, FW 0.61 (0.10)f, TLA 0.38 (0.10)g, Means of groups with the same superscript were not significantly different. Conclusion: ISO 4049 (2000) for polymer-based materials stipulates that a material must exhibit the radiopacity of an equivalent thickness of aluminum to be deemed radiopaque. Seven of the nine cements and six of the eight posts were found to meet the criteria.

This study evaluated the degree of conversion of one dual-cured resin cement when used to lute fiber posts with different translucencies. To measure the degree of conversion, polyvinylsiloxane molds were prepared to simulate root canals. The posts, Aestheti-Post or Light-Post, were cemented in these molds and, after photoactivation, were removed to obtain the resin cement spectrum by FT-Raman spectroscopy. Spectra were acquired at three depths: superficial, medium, and deep. For Light-Post, the resin cement at deep depth showed the lowest degree of conversion and no significant difference in degree of conversion was found between the other depths. For Aestheti-Post, the superficial depth presented a higher degree of conversion values than those in the medium and deep depths, which were not significantly different from each other. Light-Post exhibited a higher degree of conversion than that of Aestheti-Post only at medium depth. Light-Post effectiveness regarding the degree of conversion is dependent on the depth.

Objectives: During the last few years fiber reinforced composite (FRC) root canal post has been introduced to market. However, there still remains question of possible problem with the adhesion between highly crosslinked polymer matrix of FRC-posts and filler-composite. An alternative to resolve this problem FRC post simultaneously with the surrounding filler composite. The aim of this study was to determine the degree of conversion (DC) of resin matrix of FRC post polymerzed by light initiation in a simulated root canal.
Methods: Four different lengths (7,12,18,24 mm) of cylinders were used as a model of root canal. Two groups of cylinders where used: cylinders in Groups 1 were filled only with dimethacrylate resin (StickResin, StickTech, Finland) only. Cylinders in Groups 2 were filled with continuous unidirectional E-glass fibers (StickClassics) that have been further impregnated with resin. Specimens were light-cured (Elipar, ESPE, Germany) for 40 sec from the top of the cylinders. The bottom of the cylinder was fixed on FTIR/ATR (Fourier Transform Infrared spectroscopy/Attenuated Total Reflectance) (Spectrum One, Perkin Elmer) sample accessory and polymerisation process was analysed. Degree of conversion (DC%) was calculated from the aliphatic C=C peak at 1638 cm-1, normalised against the aromatic C=C peak at 1582 cm-1: DC% = (1-C/U)x100%, where C=absorption peak of the cured specimen, where U=absorption peak of the uncured specimen. Spectra of the sample was recorded every 2.5 min up to 5 min. Each IR-spectra was recorded with 8 scans using a resolution of 4 cm-1.
Results:

DC%/Length of cylinder(mm)
Group	7	12	18	24
1. Resin	69.2	67.3	63.9	57.0
2. Resin+glass fibers	66.8	66.0	59.0	56.1

DC%/Length of cylinder(mm) Group 7 12 18 24 1. Resin 69.2 67.3 63.9 57.0 2. Resin+glass fibers 66.8 66.0 59.0 56.1
Regression line was fitted into both models with regression coefficients of 0.946 (resin, p=0.027) and 0.938 (fibers+resin, p=0.031).
Conclusions: This in vitro study showed that sufficient degree of conversion could be achieved by exposing light from other end of glass fiber post.

Objectives: In addition to their dentinoid biomechanical properties, glass-fiber-reinforced resin posts offer advantageous optical properties because of their translucency. The study aims at comparing the translucency of four different factory-made glass-fiber-reinforced posts for visible light at a wavelength of 420 mm.
Methods: In a first step, the transfer of light through the post was documented fotographically. The following three post systems were compared: - FRC Postec™ (Ivoclar Vivadent, Schaan/Liechtenstein) - Twin Luscent Anchors™ (Dentatus, Hägersten/Sweden) - Para Post™ FIBER WHITE (Coltène Whaledent, Konstanz, Germany) In a second step, the degree of light polymerisation was qualified by measuring the hardness of the surrounding composite cement in dependence of the exposure time with the Knoop hardness test (14.000 measurements). The horizontal and vertical distances between the measuring points were 0,2 mm. The reference value was the hardness of composite cement having directly been exposed to light.
Results: Whereas the photographs of the light transfer in the FRC Postec™ and the Twin Luscent Anchors™ system show a slightly decreasing intensity of the emitted light from the head of the post to its apex, in the Para Post™ system an emission of light is found only in the head region. The results of the Knoop hardness test show that under 60 sec. of light exposure, the reference value of hardness ist reached up to an apical depth of 5 mm. Under 120 sec. of light exposure, the reference value is reached up to a depth of 7,8 mm (Twin Luscent Anchors™ ) respectively 7,4 mm (FRC Postec).
Conclusion: The results show, that the different geometrical shapes of the post systems have no significant influence on the polymerisation process. The crucial factor for the polymerisation depth is the duration of exposure to light, which should be at least 100 seconds.

Objectives: The purpose of this study was to investigate light transmission of a glass fiber post (GFP LIGHT-POST #3; RTD/Bisco) from the shape of polymerized dental resins.
Methods: The GFP was inserted into composite resins (LITE-FIL II A Shade E1 and LITE-FIL II P Shade A3 (Shofu) in a 1.5ml microtube. The upper end of the post was irradiated with a visible light generator (Griplight II, Shofu) for 20, 40 or 60 seconds. After polymerization, the unpolymerized resin around the GFP was measured. The length (A) of the polymerized resin, the diameter (B) of the upper surface and the diameter (C) of the resin 10mm below (B) were measured. Three samples were measured for each set of conditions. The data were statistically analyzed by Student’s t-test.
Results: Results showed that irradiation for 20 seconds was insufficient for polymerization, and the measurements of the samples were not possible. In the E1 resin, the value for (A) after irradiation for 60 seconds (15.5 +/- 0.3mm) was significantly larger than after 40 seconds (13.7 +/- 1.1mm) (p<0.05). In addition, the diameters of (B) were 3.7 +/-0.3 (40 seconds) and 5.3 +/- 0.3 (60 seconds), and the diameters of (C) were 6.7 +/- 0.7 (40 seconds) and 8.8 +/- 0.2 (60 sec). In the A3 resin, the extent of the resin polymerization was smaller than that in E1, although the value for (A) in the A3 resin was not significantly different from that in E1.
Conclusions: Consequently, it was concluded that the composite resins were photopolymerized using the GFP. These results suggest that irradiation of a GFP (LIGHT-POST #3) for over 40 seconds can effectively polymerize a highly translucent resin in clinical practice.