Background and Aim: Considering flexural strength of FIBER-reinforced COMPOSITEs (FRC) and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar.Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195) with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and 1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on COMPOSITE facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T test a significant statistical difference was observed between two groups (P<0.001). The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

Background and Aim: The purpose of this study was to assess the fracture resistance of two different designs of tooth preparation and FIBER placement in FIBER-reinforced COMPOSITE restorations replacing a missing mandibular lateral incisor.Materials and Methods: Forty newly extracted human mandibular intact teeth (20 centrals and 20 canines) were selected for fabrication of twenty FRC inlay bridges. A box preparation design with straight FIBERs and a slot design preparation with curved FIBERs were implemented. After preparation, the teeth were mounted in self-cured acrylic resin with 6.5 mm distance from each other. PDL was simulated with polyether material. After taking impressions with polyether material, the impressions were poured with dental stone. The two groups of bridges were fabricated and bounded to teeth with panavia F2. The cyclic load of 1.2×106×20N×1.66HZ was applied with 130O angle. The samples were stored in 37oC water for seven days and then thermo cycled (2000 cyles, 5-55oC). The fracture strength was tested by a universal testing machine (Instron 1195) at a speed of 1 mm/min. The mode of fracture was observed under stereomicroscope. The data was analyzed by using independent sample T-test.Results: The mean fracture resistance for the box design and direct FIBER group was 1411.07 N and in the slot and curved FIBERs group was 377.33 N. The group difference was statistically significant (P=0.012).Conclusion: It could be concluded that in FIBER-reinforced COMPOSITE restorations, box design with straight FIBER has more fracture resistance than slot design with curved FIBER.

Background and Aim: Over there past few years, the use of FIBER reinforced COMPOSITEs has increased in dentistry. The type of FIBER used for reinforcement plays an important role in the structural strength of COMPOSITEs. This in vitro study compares the fracture resistance of posterior reinforced COMPOSITE inlay bridges with two different FIBER types.Materials & Methods: This experimental, in vitro study was performed on 20 FRC bridges which replaced maxillary second premolars. The abutment teeth were prepared with proximal box design and the samples were divided in to two groups of 10 (n=10). For the first group polyethylene FIBER reinforced COMPOSITEs (FIBER span/ NSI/ Australia) were used directly. In second group pre impregnated glass FIBER (INTERLIG/ Angelus/ Brazil) were applied the same. After thermo cycling process (5000 cycles, 5°c / 55°c, dwell time 30s, interval 2s) fracture testing was performed in a universal testing machine (Zwick/ Roell/ Germany, 1 mm/ min) applying direct vertical force to the center of the pontic. The One Sample Kolmogorov Smirnov Test showed a normal distribution. Data analysis was done using independent sample T-test.Results: The mean fracture strength and the standard deviation of the FRC Inlay Bridge was 469 ± 247 N for polyethylene FIBER group and 541 ± 206 N for glass FIBER group. The result of Independent Sample Test was not statistically significant (P=0.491). The most failure mode observed, was crack and fracture on the surface of FPDs in distal part of the pontics. Frameworks remained with no damage in all samples. There was no stateside difference between two groups of FPDs.Conclusion: Direct application of each FIBER reinforced COMPOSITE (glass or polyethylene FIBER) with the same architecture (Braided) of FIBERs is comparable in posterior region of maxilla so the structural design of the FIBER is more important than the FIBER type itself, in fracture resistance of FPDs.

Introduction: In orthodontic treatment, adequate anchorage is necessary to move the intended teeth. In some cases, just anterior teeth are malaligned, while posterior occlusion is acceptable. Therefore, the posterior teeth could be integrated by FIBER-reinforced COMPOSITE (FRC) to provide a rigid anchorage. This method proved advantageous since brackets are bonded just to anterior segment, while posterior segments remain intact. Case description: The current article presents the orthodontic treatment of an adolescent girl with malalignment and rotation of upper incisors and canines. Posterior occlusion was admissible. Posterior anchorage was provided by FRC bars, while anterior teeth alignment was performed by routine fixed orthodontic appliances. Orthodontic treatment was completed within six months. It is worthy to note that the posterior occlusion was maintained as before treatment.

In the present study, a new method for retrofitting reinforced concrete beam is introduced in which steel-concrete COMPOSITE jackets containing steel FIBER is used. For this purpose, 75% of the peripheral surface of reinforced concrete beams was initially reinforced using steel plates and bolts, and steel FIBER reinforced concrete was used between the steel plates and the peripheral surfaces of the beam. Thus, due to the relatively high tensile strength of concrete reinforced with steel FIBERs, not only the cross-section and moment of inertia of the beam will increase, but the tensile strength of the beam will also increase. The variables studied were steel FIBER value (0, 1 and 2% by volume of concrete) and type of retrofitting (concrete jacket, steel-concrete COMPOSITE jacket, and carbon FIBER reinforced polymer (CFRP) sheet). Thus, 8 reinforced concrete beams were constructed and their response to four-point loading was compared by examining the parameters such as crack load, yield load, ultimate load, ductility, stiffness, and energy absorption capacity. The results showed that steel FIBER-reinforced COMPOSITE jackets delay the formation of the first crack in concrete and the yield of steel rebars with confinement and they result in an increase in energy absorption capacity of the beams by 89 to 129% depending on the amount of steel FIBER. On the other hand, the use of steel-concrete COMPOSITE jackets, due to their higher flexural stiffness, exhibits higher flexural capacity compared to steel-reinforced concrete jackets and CFRP sheets. They have a much better performance in terms of ductility.

In this research work, the effects of natural FIBERs such as date palm FIBER (DF) and jute FIBER (JF) on bending properties of polypropylene (PP) / ethylene-propylene-diene-monomer (EPDM) thermoplastic elastomers are investigated. For this purpose, the date palm and jute FIBERs at five levels of FIBER weight fractions (0, 5, 10, 20 and 30 wt. %) are utilized during COMPOSITE fabrication. Maleic anhydride grafted to polypropylene (MAPP) is used as coupling agent to increase the interfacial adhesion between the polymer and the FIBERs.Results show that by adding FIBER to the matrix, the bending properties are increased, but elongation at break is decreased.

Introduction: The purpose of this in vitro study was to introduce the FIBER reinforced COMPOSITE bridges and evaluate the most suitable site and position for placement of FIBERs in order to get maximum strength.Methods: The study included 20 second premolars and 20 second molars selected for fabricating twenty FIBER reinforced COMPOSITE bridges. Twenty specimens were selected for one FIBER layer and the remaining teeth for two FIBER layers. In the first group, FIBERs were placed in the inferior third and in the second group, FIBERs were placed in both the middle and inferior third region. After tooth preparation, the restorations were fabricated, thermocycled and then loaded with universal testing machine in the middle of the pontics with crosshead speed of 1 mm/min. Data was analyzed by Kolmogorov-Smirnov test, Independent sample t test and Kaplan-Meier test. Mode of failure was evaluated using stereomicroscope.Results: Mean fracture resistance for the first and second groups was 1416±467 N and 1349±397 N, respectively. No significant differences were observed between the groups (P>0.05).In the first group, 5 specimens had delamintation and 5 specimens had detachment between FIBERs and resin COMPOSITE. In the second group, there were 4 and 6 delaminations and detachments, respectively. There was no fracture within the FIBER.Conclusion: In the FIBER reinforced fixed partial dentures, FIBERs reinforce the tensile side of the connectors but placement of additional FIBERs at other sites does not increase the fracture resistance of the restoration.

Background and Aim: One of the most important factors for increasing flexural strength of FIBER-reinforced COMPOSITE (FRC) restorations is the orientation, volume and geometry of reinforcement FIBERs. The aim of this study was to determine the effect of FIBER position and orientation on the flexural strength of FRC specimens.Materials and Methods: In this experimental-laboratory study, five groups (N=8) of test specimens made of one indirect COMPOSITE were reinforced with pre-impregnated FIBERs in different positions, orientations or geometry into the rectangle cube specimens (3×3×25 mm3). The control group did not contain FIBER reinforcement. The test specimens were stored in distilled water for 1 week at 37oC before testing in a three-point loading test with 1 mm/min cross head speed. Data were statistically analyzed at 0.05 significance level with Kruskal-Wallis and Mann-Whitney tests.Results: The mean flexural strength of six experimental groups had significant differences (p1=0.005 and p2<0.001). The control group showed the lowest initial and final values. The maximum initial flexural strength was seen in the tension group (76.2 MPa) and the maximum final flexural strength was seen in the middle horizontal group (173.9 MPa).Conclusion: Within the limitations of this study, it may be concluded that the position and orientation of the FIBERs influenced the flexural strength of the FIBER-reinforced COMPOSITEs and the most effective position of the FIBERs was tension side reinforcement.

In the present study, comparative study on the damage behaviour of Glass-Epoxy (GE), Jute-Epoxy (JE) laminates with [0/90]s orientation and Jute-Rubber-Jute (JRJ) sandwich is carried out using ABAQUS/CAE finite element software. The GE, JE laminate and JRJ sandwich with thickness of 2 mm is impacted by a hemispherical shaped impactor at a velocity of 2. 5 m/s. The mechanisms in which the brittle laminate gets damaged are analyzed using Hashin’ s 2D failure criteria and flexible COMPOSITEs are analysed by ductile damage mechanism. The energy absorbed and the incipient point of each laminate was compared. It was observed from the results that there is no evidence of delamination in JRJ as opposed to GE and JE. The compliant nature of rubber contributes in absorbing more energy and it is slightly higher than GE. Also it was observed that there is no incipient point in JRJ sandwich which means there is no cracking of matrix since rubber is elastic material. Thus the JRJ material can be a better substitute for GE laminate in low velocity applications. The procedure proposed for the analysis in the present study can serve as benchmark method in modelling the impact behaviour of COMPOSITE structures in further investigations.