Fiber Insertion Research Articles

Effect of Different Fiber Reinforcement Strategies on the Fracture Strength of Composite Resin Restored Endodontically Treated Premolars

Objective: To compare the effect of three different fiber reinforcement strategies on the fracture strength of composite resin restored endodontically treated premolars. Material and Methods: Seventy-two sound human premolars extracted for orthodontic reasons were divided into 6 groups (n=12) after endodontic treatment. Group 1: intact teeth (positive control); Group 2: endodontically treated teeth without restoration (negative control); Group 3: composite resin restoration; Group 4: placement of fibers at occlusal position; Group 5: splinting the buccal and palatal walls with horizontal fiber posts; Group 6: placement of fibers at the occlusal position after splinting the buccal and palatal walls with horizontal fiber posts. Then fracture strength was measured at a crosshead speed of 0.5 mm/min in a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests at α =0.05. Results: There were significant differences between the negative and positive control groups (p 0.05). Conclusion: Fiber insertion had no additional reinforcing effect on the fracture strength following composite resin restoration.

Fracture Resistance of Endodontically Treated Maxillary Premolars Restored With Different Methods.

The purpose of this in vitro study was to evaluate the resistance and patterns of fracture of endodontically treated maxillary premolars (ETPs) restored with different methods. Mesio-occluso-distal cavities were prepared in 50 extracted caries-free human maxillary premolars after endodontic treatment. The teeth were divided into five groups (n=10), according to the restorative method. G1: intact teeth (control group); G2: conventional composite resin; G3: conventional composite resin with a horizontal glass fiber post inserted between buccal and palatal walls; G4: bulk-fill flowable and bulk-fill restorative composites; and G5: ceramic inlay. For direct restorations, Filtek Z350 XT, Filtek Bulk Fill Flowable Restorative, and Filtek Bulk Fill Posterior Restorative were used. Indirect restorations were fabricated from a pressable lithium disilicate glass-ceramic (IPS e-max Press) and adhesively cemented (RelyX Ultimate). All specimens were subjected to thermocycling (5°C to 55°C/5000 cycles) and additionally submitted to cyclic loading 50,000 times in an Electro-Mechanical Fatigue Machine. Next, the specimens were subjected to a compressive load at a crosshead speed of 1 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern using a stereomicroscope, and then representative specimens were carbon coated to allow for the studying of the fracture surface under scanning electron microscopy. One-way analysis of variance (ANOVA) was used to compare fracture resistance of the groups. The results of fracture patterns were submitted to the Fisher exact test (α=0.05). All specimens survived fatigue. Mean (standard deviation) failure loads (N) for groups were as follows: G1: 949.6 (331.5); G2: 999.6 (352.5); G3: 934.5 (233.6); G4: 771.0 (147.4); and G5: 856.7 (237.5). The lowest fracture resistance was recorded for G4, and the highest ones were recorded for G2, followed by that of G1 and G3. One-way ANOVA did not reveal significant differences between groups ( p>0.05). The highest repairable fracture rates were observed in G1 (100%) and G3 (80%). ETPs restored with conventional composite resin with or without horizontal fiber post, bulk-fill composite, and ceramic inlay showed fracture resistance similar to that of sound teeth. Conventional composite resin restorations exhibited the highest prevalence of unrepairable fractures, and the insertion of a horizontal fiber post decreased this prevalence. Intact teeth showed 100% of repairable fractures. It is difficult to extrapolate the results directly to a clinical situation due to the limitations of this study.

RETRACTED: Large Timescale Interrogation of Neuronal Function by Fiberless Optogenetics Using Lanthanide Micro-particles

Optogenetics requires implantation of light-delivering optical fibers, as current light-sensitive opsins are activated by visible light, which cannot effectively penetrate biological tissues. Insertion of optical fibers and subsequent photostimulation inherently damages brain tissue, and fiber tethering can restrict animal behavior. To overcome these technical limitations, we developed minimally invasive "fiberless" optogenetics using lanthanide micro-particles (LMPs), which emit up-conversion luminescence in the visible spectrum in response to irradiation with tissue-penetrating near-infrared light. Depolarizing (C1V1) and hyperpolarizing (ACR1) opsins were strongly activated by up-conversion luminescence from green-emitting LMPs both invitro and invivo. Using this technique, we successfully manipulated locomotive behavior ofmice by activating and inhibiting neurons in the dorsalstriatum, at a depth of 2mm from the brain surface. LMPs were retained and remained functional for >8weeks at the injection site. Fiberless optogenetics offers opportunities to control neuronal function overlonger time frames using freely behaving animals.

Modified Lemaire Lateral Extra-Articular Tenodesis Augmentation of Anterior Cruciate Ligament Reconstruction.

A modified Lemaire lateral extra-articular tenodesis (LET) is a procedure that is designed to address anterolateral complex (ALC) deficiency. The procedure is performed as an augmentation to anterior cruciate ligament reconstruction (ACLR) to reduce anterolateral rotatory laxity. Studies have demonstrated improved rotational control and reduced failure rates of ACLR when LET is added. This is particularly helpful in young patients with high-grade rotatory laxity returning to contact pivoting sport, and in the revision ACLR scenario. A 6-cm skin incision is placed just posterior to the lateral epicondyle. The subcutaneous tissue is dissected down to the iliotibial band (ITB). A 1-cm-wide by 8-cm-long strip of the posterior half of the ITB is fashioned, leaving the distal attachment at Gerdy's tubercle intact. The free end is whipstitched with number-1 Vicryl suture, tunneled deep to the fibular collateral ligament (FCL), and attached to the metaphyseal flare of the lateral femoral condyle at the insertion of the distal Kaplan fibers of the ITB. Fixation is performed with a staple, with the graft tensioned to no more than 20 N (by simply holding it taut and not "tensioned"), with the knee held at 60° of flexion and neutral rotation of the tibia. A number of procedures to address ALC deficiency have been described. The most common methods currently are variations of the ITB LET (Lemaire [ITB graft detached proximally, passed under the FCL, and attached to the femur] or Ellison [ITB graft detached distally, passed deep to the FCL, and reattached at Gerdy's tubercle]) or anterolateral ligament reconstructions. No clinical studies have been performed that demonstrate that one technique is superior to another. Current ACLR procedures focus on intra-articular graft placement to replace the ACL. Unfortunately, high rates of graft failure and persistent rotatory laxity (pivot shift) have been observed, particularly in young, high-demand individuals returning to contact pivoting sport. ALC deficiency has been shown to be a major cause of high-grade anterolateral rotatory laxity. The LET procedure is therefore designed to augment ACLR and reduce anterolateral rotation. The aim of adding LET to ACLR is to reduce the strain on the ACLR graft, reduce the prevalence of the pivot shift, and thereby potentially reduce the rate of ACLR graft failure.

Mechanical properties of 3D printed composites with ABS/ASA substrate and glass fiber inserts

3D printed specimens (ASTM D638 Type I) were manufactured from ABS and ASA material via additive manufacturing through material extrusion 3D printing (ME3DP). During manufacturing, the printing process has been paused, pre-impregnated biaxial or uniaxial glass fiber mesh has been placed onto the ABS/ASA substrate and then the printing process has been resumed. The obtained composite specimens have been subjected to tensile strength testing and results have been compared to those of specimens printed from homogenous material. The influence of raster angle, glass fiber direction and mesh density on resulting toughness has also been analyzed. It was found that inserting uniaxial glass fiber increases toughness of specimens in the axial direction, with a drop in layer adhesion if biaxial fiber is used. Test specimens manufactured with 30 uniaxial fiber strands embedded in a 0o raster angle 3D printed thermoplastic matrix match mechanical characteristics of injection-molded parts. The maximum mesh density without leading to delamination is one layer of glass fiber every two layers of thermoplastic matrix.

Experimental studies on the compound thermo-hydraulic characteristics in a 3D inner finned tube with porous copper fiber inserts

A novel easy-to-manufacture porous copper fiber sintered cylinder insert (PCFSCI) is designed to enhance the convective heat transfer performance in a three-dimensional inner finned tube (3D-IFT). The compound heat transfer enhancement of the PCFSCI and 3D inner fins is investigated at the Reynolds number ranging from 3921 to 14,290. The results show that the combination of PCFSCI and 3D-IFT creates a synergistic effect and a maximum performance evaluation criterion (PEC) value of 2.29. Moreover, the effect of porosity, diameter and spacing of the PCFSCI on heat transfer performance is investigated. The results show that the Nusselt number and friction factor increase with the decrease of porosity. The PCFSCI with a diameter of 8 mm presents a better PEC than PCFSCI with diameters of 12 mm and 10 mm. The spacing has a slight effect on the PEC, but a great influence on the Nusselt number and friction factor. These phenomena can be attributed to the fluid mixing between the core flow and the flow in the annular region, as well as the local vortexes and the changing of velocity gradient produced in the annular region.

Behaviour of fibre-reinforced cemented sand under flexural tensile stress

In soil improvement, the insertion of cement to the soil matrix provides an increase in strength and rigidity of the material, whereas fibre addition provides an increase in ductility, reducing post-peak loss in strength. This research aims to experimentally analyse the mechanical behaviour of unreinforced and fibre-reinforced cemented sands under flexural tensile monotonic loading conditions. In order to do so, an experimental program was planned using silty sand (Arenito Botucatu), early strength Portland cement – CPIII, and polypropylene fibres 24 mm long and 0.023 mm thick. Three different dry unit weights (γd) (18, 19 and 19.7 kN/m3), three cement contents (3, 5 and 7%), and two fibre contents (0 and 0.5%) were chosen. Analysing the results, an increase in cement content generates an increase in flexural strength (qf) for all concentrations and the increase in γd generated smaller qf gains, especially for lower cement contents. The addition of fibres generated a qf increase for lower γd but at higher γd there was a reduction in the influence of fibre addition on strength gain. The reduction can be attributed to an entanglement of the fibres in higher compaction strengths, disrupting the formation of cementitious bonds. However, based on a qualitative assessment, there was a noticeable reduction in post-peak strength loss due to fibre insertion. The parameter porosity/volumetric cement content (η/Civ0.28) was considered suitable to predict the qf mechanical behaviour of the studied composite.

Mechanical Characteristics of Green Composites of Short Kenaf Bast Fiber Reinforced in Cardanol

In this experiment, thermoset cardanol resin was reinforced with short kenaf bast fibers to produce 100% green composites. Different fiber loadings based on weight ratios (0%, 30%, 40%, 50%, and 60%) were fabricated by the hand layup method followed by compression molding. The results indicated that 50UTK (untreated kenaf fibers) displays the highest mechanical properties (91.9% and 43.4% increment for tensile strength and impact strength, respectively) compared with the brittle cardanol polymer and other combinations of composite. This indicates a great load transfer mechanism by kenaf fiber reinforcement due to good fiber/matrix interface shown in scanning electron microscope (SEM) analyses. On the contrary, short kenaf fiber insertion creates a stress concentration spot at the fiber’s end causing slightly lower flexural properties. Besides, high processing temperature has caused damage to the fibers and made further reduction of flexural strength. Therefore, a better load transfer mechanism has been compensated by negative influences of kenaf fiber insertion. In conclusion, 50 wt% of kenaf fiber insertion is found to be the optimum loading for cardanol matrix.

Miniature ureteroscope distal tip designs for potential use in thulium fiber laser lithotripsy.

Thulium fiber laser lithotripsy using smaller optical fibers may enable development of miniature ureteroscopes. Two ureteroscope distal tip prototypes were built and characterized. The first design was 4.5-French (Fr) [1.5-mm outer diameter (OD)], five channel tip, housing 200-μm inner diameter (ID) dedicated central channel for insertion of 100-μm core fibers and four surrounding channels, each with 1.5Fr (510-μm ID) for instrumentation, irrigation, imaging, and illumination, respectively. The second design was 6.0-Fr (2.0-mm OD), three-dimensional printed tip with larger, hemispherical common working channel and separate detection port integrated with ring lighting. Standard instruments, including optical fibers, guidewires, and stone baskets, were inserted through working channels to demonstrate feasibility. Gravitational and manual pump-assisted saline irrigation rates were measured. Luminous intensity distribution curves (LIDCs) were modeled for both ring and conventional lighting designs. Imaging was conducted using 3000, 6000, and 10,000pixel, miniature, flexible endoscopes with 0.4-, 0.6-, and 0.9-mm OD, to differentiate between urinary stones and ureter wall, for potential clinical application. The multichannel ureteroscope tip with 1.5-Fr working channel yielded a gravitational saline flow rate of 3.9 ± 0.2 mL / min compared to 31.3 ± 0.6 mL / min for standard (3.6Fr) ureteroscope channel. Manual, pump-assisted irrigation increased flow rate to 32.5 ± 3.0 mL / min. The 6000pixel, 0.6-mm OD, flexible endoscope provided a balance of clear differentiation between stones and ureter wall and sufficiently small OD. A ring lighting configuration provided more uniform illumination than conventional cross-lighting geometry as demonstrated by LIDCs. With further development, these miniature ureteroscope tip designs may be integrated into a fully functional ureteroscope to permit ureteral access with minimal trauma and improved patient safety and comfort.

In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters.

This technique combines optical fiber mediated fluorescence recordings with the precise delivery of recombinant adeno-associated virus based gene reporters. This new and easy to use in vivo fluorescence monitoring system was developed to record the transcriptional rhythm of the clock gene, Cry1, in the suprachiasmatic nucleus (SCN) of freely moving mice. To do so, a Cry1 transcription fluorescence reporter was designed and packaged into Adeno-associated virus. Purified, concentrated virus was injected into the mouse SCN followed by the insertion of an optic fiber, which was then fixed onto the surface of the brain. The animals were returned to their home cages and allowed a 1-month post-operative recovery period to ensure sufficient reporter expression. Fluorescence was then recorded in freely moving mice via an in vivo monitoring system that was constructed at our institution. For the in vivo recording system, a 488 nm laser was coupled with a 1 × 4 beam-splitter that divided the light into four laser excitation outputs of equal power. This setup enabled us to record from four animals simultaneously. Each of the emitted fluorescence signals was collected via a photomultiplier tube and a data acquisition card. In contrast to the previous bioluminescence in vivo circadian clock recording technique, this fluorescence in vivo recording system allowed the recording of circadian clock gene expression during the light cycle.

Early Return To Play After Intramedullary Screw Fixation Of Jones Fractures In Collegiate Athletes: 23 Year Experience

Objectives:There is a general consensus that Jones fractures should be treated operatively with an intramedullary screw in high-level athletes. However, there is disagreement among team physicians, without conclusive evidence as to when the athlete should be allowed to return to play. The objective of this study is to report our experience of early return to sport in collegiate athletes after intramedullary screw fixation of Jones Fractures.Methods:All skeletally mature collegiate athletes with a true Jones fracture of the base of the fifth metatarsal that was treated by one of two orthopaedic surgeons with operative intramedullary screw fixation over a 23 year period (1994-2016) were identified and records reviewed retrospectively. All return to play and complication data was obtained from the athletic trainer database at the two universities. Fixation consisted of a single intramedullary screw (10 partially threaded cannulated screws, 13 cannulated variable pitch screws, 3 solid screws). The athletes were allowed to weight bear as tolerated in a CAM boot immediately postoperatively, and return to play with a carbon fiber insert as soon as they could tolerate activity. In 2016, patients were contacted to complete patient reported outcome scores that included the Foot and Ankle Ability Measure (FAAM) score and a brief survey specific to our study, as well as follow-up radiographs if possible.Results:26 Jones Fractures were treated in 25 collegiate athletes. The average age was 20 years (18-23). Overall, athletes returned to play or training at an average of 3.5 weeks (1.5-6). All in-season athletes returned to play within 4.5 weeks (1.5-4.5). Off-season athletes returned to play within 4-6 weeks. There were no cases of nonunion (clinically or radiographically). Three screws were removed due to symptomatic skin irritation. There was one re-fracture following screw removal after documented radiographic and clinical fracture union. This patient was treated with repeat cannulated percutaneous screw fixation. The athlete returned to play in 2 weeks. One screw was noted to be broken on an ankle radiograph 1 year post-op, but the fracture was healed and the athlete was playing division 1 sports without symptoms, and continued professionally without symptoms. 18/25 athletes completed patient reported outcome scores at an average of 7.95 years (range 1.2-17) follow-up. The average estimated percent of normal for activities of daily living was 93.8% (70-100%, and for athletic participation was 90.3% (40-100%). Follow up radiographs were obtained on 13/26 fractures at an average of 6.48 years (range 1.2-16) with no nonunion, malunion, or additional hardware complications identified.Conclusion:Athletes with Jones fractures can safely be allowed to return to play after intramedullary screw fixation as soon as their symptoms allow without significant complications. In our experience, this is usually within 4 weeks from injury.

Photothrombotically induced unilateral selective hippocampal ischemia in rat

IntroductionThe vulnerability of hippocampal formation to ischemic insult has been documented in both humans and animal models. Ischemic injury induction through photothrombosis is an invasive and reproducible model of ischemic stroke which provides the ability to induce ischemia selectively in any desired area. In this study, we describe a method to induce selective unilateral hippocampal ischemia in rat through modified photothrombotic model. MethodsMale wistar rats (n = 66) were subjected to stereotaxic surgery to insert a guide cannula just above the ascending part of hippocampal fissure. After recovery femoral vein was cannulated and rats were mounted in stereotaxic frame to optical fiber insertion in guide cannula and illumination of hippocampal fissure for 25 min. Rose Bengal dye was slowly injected through femoral vein during the first two-minute of illumination. Twenty-four hours later, infarct volume and histological change were evaluated in rat hippocampus. Cognitive function was also evaluated 48 h after ischemia induction. ResultsThis procedure caused significant neuronal necrosis and infarct formation in the right hemisphere hippocampus. The infarct size was consisted in different subjects and was paralleled to cognitive impairment. The mean volume of infarction was 6.5% which affected whole right hippocampus and caused significant cognitive impairment compared to sham group (P < 0.001). DiscussionThe method described in this study provides the ability of selective hippocampal ischemia induction and study of hippocampal injury consequences following ischemia or other neurodegenerative disease that affect hippocampus.

Reconstruction of a Deformed Tumor Based on Fiducial Marker Registration: A Computational Feasibility Study

Interstitial photodynamic therapy has shown promising results in the treatment of locally advanced head and neck cancer. In this therapy, systemic administration of a light-sensitive drug is followed by insertion of multiple laser fibers to illuminate the tumor and its margins. Image-based pretreatment planning is employed in order to deliver a sufficient light dose to the complex locally advanced head-and-neck cancer anatomy, in order to meet clinical requirements. Unfortunately, the tumor may deform between pretreatment imaging for the purpose of planning and intraoperative imaging when the plan is executed. Tumor deformation may result from the mechanical forces applied by the light fibers and variation of the patient’s posture. Pretreatment planning is frequently done with the assistance of computed tomography or magnetic resonance imaging in an outpatient suite, while treatment monitoring and control typically uses ultrasound imaging due to considerations of costs and availability in the operation room. This article presents a computational method designed to bridge the gap between the 2 imaging events by taking a tumor geometry, reconstructed during preplanning, and by following the displacement of fiducial markers, which are initially placed during the preplanning procedure. The deformed tumor shape is predicted by solving an inverse problem, seeking for the forces that would have resulted in the corresponding fiducial marker displacements. The computational method is studied on spheres of variable sizes and demonstrated on computed tomography reconstructed locally advanced head and neck cancer model. Results of this study demonstrate an average error of less than 1 mm in predicting the deformed tumor shape, where 1 mm is typically the order of uncertainty in distance measurements using magnetic resonance imaging or computed tomography imaging and high-quality ultrasound imaging. This study further demonstrates that the deformed shape can be calculated in a few seconds, making the proposed method clinically relevant.

Molding of Polymeric Composite Reinforced with Glass Fiber and Ceramic Inserts: Mathematical Modeling and Simulation

This work provides a numerical study of a polymer composite manufacturing by using liquid composite material molding. Simulation of resin flow into a porous media comprising fiber perform (reinforcement) inserted in a mold with preallocated ceramic inserts has been performed, using the Ansys FLUENT® software. Results of resin volumetric fraction, stream lines and pressure distribution inside the mold, and mass flow rate (inlet and outlet gates) of the resin, as a function of filling time, have been presented and discussed. Results show that the number of inserts affects the filling time whereas the distance between them has no influence in a process.

Anatomical variant of the meniscus related to posterior junction: a case report

BackgroundThere are several reports on anatomical differences of the meniscus. However, there are only a few reports on abnormalities in both menisci and anatomical differences in anterior cruciate ligament insertions.Case presentationThis is a case report of a 36-year-old Hispanic man presenting symptoms, including knee pain, locking, and effusion, with an anatomical abnormality of the menisci corresponding to the fusion of the posterior horns of the menisci in tandem with the insertion of the posterior meniscus fibers in the anterior cruciate ligament.ConclusionsThis is the first study describing a meniscus anatomical variant with isolated posterior junction of the posterior horn with an anomalous insertion to the anterior cruciate ligament. The recognition of meniscus variants is important as they can be misinterpreted for more significant pathology on magnetic resonance images.

EFFECT OF SHORT FIBERS ORIENTATION ON MECHANICAL PROPERTIES OF COMPOSITE MATERIAL – FIBER REINFORCED CONCRETE

Traditional fiberconcrete structures have fibres in the mix oriented in all spatial directions, distributed in the struc­tural element volume homogenously, what not easy to obtain in practice. In many situations, structurally more effective is the insertion of fibres into the concrete structural element body by forming layers, with a predetermined fibre concentration and orientation in every layer. In the present investigation, layered fibre concrete is under investigation. Short steel fibres were at­tached to flexible warps with the necessary fibres concentration and orientation. Warps were placed into the prismatic mould separating them by concrete layers without fibres. Prisms were matured and tested under four-point bending. The bending-affected mechanical behaviour of cracked fibre concrete was simulated numerically by using a developed struc­tural model. Comparing the simulation results with experimental data, material micromechanical fracture mechanisms were analysed and evaluated.

Zoledronate Impairs Socket Healing after Extraction of Teeth with Experimental Periodontitis

Osteonecrosis of the jaws (ONJ) is a rare but severe complication of antiresorptive medications, such as bisphosphonates, used in the treatment of bone malignancy or osteoporosis. Tooth extraction and dental disease have been strongly associated with ONJ development. Here, we investigated molecular and cellular markers of socket healing after extraction of healthy or teeth with experimental periodontitis (EP) in Wistar-Han rats treated with zoledronic acid (ZA). We included 4 experimental groups: vehicle-treated animals with extraction of healthy teeth or teeth with ligature-induced EP and ZA-treated animals with extraction of healthy teeth or teeth with EP. Animals were pretreated with vehicle or ZA for a week, and EP was induced. Four weeks later, the second maxillary molars were extracted; sockets were allowed to heal for 4 wk; animals were euthanized; and maxillae were isolated. Radiographically, extraction sockets in groups 1, 2, and 3 demonstrated normal healing. Contrary incomplete socket healing was noted after extraction of teeth with EP in ZA-treated rats of group 4. Histologically, persistent inflammation and extensive osteonecrosis were seen in group 4. Disorganization of the collagen network, collagen type III predominance, and lack of collagen fiber insertion in the necrotic bone were associated with impaired socket healing. Cells positive for MMP-9, MMP-13, and α-SMA expression were present at the areas of epithelial invagination and adjacent to osteonecrotic bone. Importantly, human biopsies from patients with ONJ showed similar findings. Our data emphasize the importance of dental disease and tooth extraction in ONJ pathogenesis and help delineate an altered profile in wound-healing markers during ONJ development.

In vivofiber photometry of neural activity in response to optogenetically manipulated inputs in freely moving mice

In vivo fiber photometry is a powerful technique to analyze the dynamics of population neurons during functional study of neuroscience. Here, we introduced a detailed protocol for fiber photometry-based calcium recording in freely moving mice, covering from virus injection, fiber stub insertion, optogenetical stimulation to data procurement and analysis. Furthermore, we applied this protocol to explore neuronal activity of mice lateral-posterior (LP) thalamic nucleus in response to optogenetical stimulation of primary visual cortex (V1) neurons, and explore axon clusters activity of optogenetically evoked V1 neurons. Final confirmation of virus-based protein expression in V1 and precise fiber insertion indicated that the surgery procedure of this protocol is reliable for functional calcium recording. The scripts for data analysis and some tips in our protocol are provided in details. Together, this protocol is simple, low-cost, and effective for neuronal activity detection by fiber photometry, which will help neuroscience researchers to carry out functional and behavioral study in vivo.

Effects of the incorporation of ε-aminocaproic acid/chitosan particles to fibrin on cementoblast differentiation and cementum regeneration.

Cementum, the mineralized layer on root dentin surfaces, functions to anchor fibrous connective tissues on tooth-root surfaces with the collagenous Sharpey's fibers integration, of which are essential for periodontal functioning restoration in the complex. Through the cementum-responsible fiber insertions on tooth-root surfaces, PDLs transmit various mechanical responses to periodontal complexes against masticatory/occlusal stimulations to support teeth. In this study, periodontal tissue regeneration was enhanced by use of modified fibrin biomaterial which significantly promoted cementogenesis within the periodontal complex with structural integration by collagenous Sharpey's fiber insertions in vivo by controlling fibrin degradation and consequent cementoblast apoptosis. Furthermore, the modified fibrin could improve repair and regeneration of tooth roof-of-furcation defects, which has spatial curvatures and geometrical difficulties and hardly regenerates periodontal tissues.

Poly(lactic acid) foams reinforced with cellulose micro and nanofibers and foamed by chemical blowing agents

Biodegradable polymeric foams have gained increasing attention as an alternative to conventional polymeric foams, whose recycling is economically unviable due to its low density. Based on this, this article discusses the development of poly(lactic acid) foams produced with the insertion of four and eight parts hundred resin (phr) of long and short cellulose fibers and nanofibers. Short fibers of nanocellulose were obtained by mechanical defibrillation and dried by lyophilization, and long fibers by CO2 supercritical fluid extraction. The poly(lactic acid) foams were produced by adding a chemical blowing agent with a pressure-free expansion method. In general, short fibers of cellulose act as nucleating agents during the expansion of the foam, which is observed by its greater number of smaller-size cells than the non-reinforced poly(lactic acid) foams. The insertion of long fibers of cellulose restricts the mobility of the polymer matrix during the expansion, thus hindering the foam its growth and formation of bubbles.