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Papers by sinan şen

International Journal of Molecular Sciences, 2021

Background: Induced tooth movement during orthodontic therapy requires mechano-induced bone remod... more Background: Induced tooth movement during orthodontic therapy requires mechano-induced bone remodeling. Besides various cytokines and growth-factors, neuronal guidance molecules gained attention for their roles in bone homeostasis and thus, potential roles during tooth movement. Several neuronal guidance molecules have been implicated in the regulation of bone remodeling. Amongst them, Semaphorin 3A is particular interesting as it concurrently induces osteoblast differentiation and disturbs osteoclast differentiation. Methods: Mechano-regulation of Sema3A and its receptors PlexinA1 and Neuropilin (RT-qPCR, WB) was evaluated by applying compressive and tension forces to primary human periodontal fibroblasts (hPDLF) and alveolar bone osteoblasts (hOB). The association of the transcription factor Osterix (SP7) and SEMA3A was studied by RT-qPCR. Mechanisms involved in SEMA3A-mediated osteoblast differentiation were assessed by Rac1GTPase pull-downs, β-catenin expression analyses (RT-qPC...

Journal of Composite Materials, 2021

Polypropylene (PP)/poly (ethylene-co-vinyl acetate) (EVA) nanocomposites were prepared with use o... more Polypropylene (PP)/poly (ethylene-co-vinyl acetate) (EVA) nanocomposites were prepared with use of 3 wt% of organophilic halloysite nanotubes (Org-HNTs) and 3 types of compatibilizers in two steps. First, masterbatchs of EVA and the compatibilizers with the Org-HNT were prepared by two different preparation techniques; melt masterbatch (MM) and solution masterbatch (SM). The masterbatchs were then melt compounded with PP in the second step. Special attention was paid to effects of nature of compatibilizer and masterbatch preparation technique on morphology-mechanical property relationship for the composites. Poly(ethylene-vinyl acetate-carbon monoxide) (EVACO) and maleic anhydride grafted EVA (EVA-g-MA) were used as EVA-based compatibilizers which gave a homogeneous distribution of the nanotubes in the matrix and at the matrix-elastomer interphase as compared to maleic anhydride grafted PP (PP-g-MA). The both masterbatch techniques provided a core-shell morphology composed of nanotu...

Clinical Oral Investigations, 2020

Objectives The aim of this single-center randomized controlled trial (NCT03753256) was to assess ... more Objectives The aim of this single-center randomized controlled trial (NCT03753256) was to assess orthodontic surface sealant layer thickness and integrity in vivo during a 12-month follow-up by optical coherence tomography (OCT). Materials and methods Using a split-mouth design, quadrants of 20 patients treated with fixed orthodontic appliances were included. Quadrants were randomly assigned to the sealants Pro Seal® (PS) or Opal® Seal™ (OS). OCT scans were performed immediately after the application of the sealants and after 3, 6, 9, and 12 months. Sealant layer thicknesses and their integrity were determined at 5 regions of interest (ROIs) known for high risks of demineralization. Sealant integrity loss was determined using a self-developed scale. Results A total of 16 patients successfully completed the study. The studied sealants showed significant differences in initial layer thickness. Mean layer thickness was significantly lower for PS (67.8 μm, (95% CI, 56.1-79.5)) than for OS (110.7 μm, (95% CI, 97.3-124.1)). Layer thickness loss was significant after 3 months for PS and after 6 months for OS. Sealant integrity was compromised in more than 50% of the ROIs already after 3 months for both sealants. Conclusions Patients treated with fixed orthodontic surface sealants lost the integrity of the protective layer in more than 50% of cases after 3 months, and the layer thickness of the sealants was significantly reduced after 3-6 months. Clinical relevance The protective effect against demineralization lesions of orthodontic sealants in patients treated with fixed appliances appears to be limited in time. Further preventive measures should be investigated. Trial registration ClinicalTrials.gov (NCT 03753256

Journal of Orofacial Orthopedics / Fortschritte der Kieferorthopädie, 2020

Purpose Surface sealants are widely used as a prevention strategy and are indicated for young pat... more Purpose Surface sealants are widely used as a prevention strategy and are indicated for young patients with insufficient oral hygiene who also need plaque removal by professional tooth cleaning. The aim of this study was to evaluate discoloration of surface sealants by plaque disclosing solutions and to test to what extent this discoloration can be reduced again by professional tooth cleaning. Methods In all, 96 extracted lesion-free human teeth were randomly assigned to treatment with either Pro Seal ® (PS; Opal Orthodontics, South Jordan, UT, USA) or Opal ® Seal™ (OS; Reliance Orthodontic Products, Itasca, IL, USA). Color evaluations after application of the plaque disclosing solution Mira-2-Ton ® (Hager & Werken, Duisburg, Germany) were performed using a clinical spectrophotometer. Staining and polishing were repeated once. Color differences (E) above 3.77 were regarded as clinically relevant. Results All sealants showed high, clinically relevant E values after the first staining. Polishing led to significantly decreased E values on PS-treated teeth; however, the median E value remained above the clinically relevant threshold. Polishing on OS-treated teeth only slightly reduced E values. After professional tooth cleaning both PS and OS showed clinically relevant E values. Conclusion Surface sealants show clinically relevant discoloration after exposure to plaque disclosing solution under in vitro conditions. Such discolorations could not be removed by professional tooth cleaning. Thus, in clinical practice, plaque disclosing solutions might cause esthetic deficits in surface sealant-treated teeth. The impact of plaque disclosing solutions under clinical conditions (e.g., in the presence of saliva and by various aspects of a person's nutrition) should be investigated in clinical studies.

BioMed Research International, 2020

Objectives. Bilateral sagittal split osteotomy (BSSO) is a common surgical procedure to correct d... more Objectives. Bilateral sagittal split osteotomy (BSSO) is a common surgical procedure to correct dentofacial deformities that involve the mandible. Usually bicortical bone fixation screw or miniplates with monocortical bone fixation screw were used to gain stability after BSSO. On the other hand, the use of resorbable screw materials had been reported. In this study, our aim is to determine first stress distribution values at the temporomandibular joint (TMJ) and second displacement amounts of each mandibular bone segment.Methods. A three-dimensional virtual mesh model of the mandible was constructed. Then, BSSO with 9 mm advancement was simulated using the finite element model (FEM). Fixation between each mandibular segment was also virtually performed using seven different combinations of fixation materials, as follows: miniplate only (M), miniplate and a titanium bicortical bone fixation screw (H), miniplate and a resorbable bicortical bone fixation screw (HR), 3 L-shaped titanium...

Clinical Oral Investigations, 2019

Objectives Demineralizations such as white spot lesions are among the most prevalent side effects... more Objectives Demineralizations such as white spot lesions are among the most prevalent side effects during orthodontic treatment. Fluorescence devices, including quantitative light-induced fluorescence (QLF), exploiting the intrinsic fluorescence of enamel and teeth and most recently optical coherence tomography (OCT) were introduced for early demineralization detection. In addition to near-infrared OCT scanning, multicolor modules allow for imaging with different laser wavelengths and the detection of reflective-and fluorescent light. The aim of this study was to evaluate a modified multicolor ophthalmic OCT device for the detection of early carious lesions in vitro and in vivo. Materials and methods Twenty-seven extracted lesion free human teeth were randomly assigned to three different demineralization protocols. Carious lesion detection was performed using macrophotography, OCT, and reflectance/fluorescence imaging using green laser and blue laser light. In addition, teeth of 5 orthodontic patients were OCT scanned, and fluorescence imaging using blue laser light was performed to assess demineralization after orthodontic therapy. Results Both in vitro and in vivo, OCT allowed for precise determination of lesion depth and enamel loss. Fluorescence imaging using blue laser light was most sensitive for the detection of early demineralization in vitro and in vivo. However, established and severe demineralizations were also reliably detected by macrophotography in vitro and in vivo. Conclusion Demineralization can be detected with high sensitivity using blue fluorescence imaging with multicolor OCT devices. Clinical relevance In the future, OCT fluorescence imaging might be considered for longitudinal monitoring of dental hard tissue during orthodontic treatment in clinical trials.

Journal of Thermoplastic Composite Materials, 2019

Poly(styrene -b-ethylene- co-butylene -b-styrene) (SEBS)/organophilic halloysite nanotube (Org-HN... more Poly(styrene -b-ethylene- co-butylene -b-styrene) (SEBS)/organophilic halloysite nanotube (Org-HNT) nanocomposites were prepared by solution mixing and then compression molded. Maleic anhydride grafted SEBS (SEBS- g-MA) was also used as a compatibilizer in preparation of SEBS/SEBS- g-MA/Org-HNT ternary nanocomposites. Surface morphologies and both static and dynamic mechanical analyses as well as thermal stabilities of the nanocomposites were carried out. Both the binary and ternary nanocomposites exhibited higher tensile moduli, tensile strength, and toughness values compared to neat SEBS. The elastic modulus was found to increase about 385% and 320% with addition of 3 and 5 phr Org-HNT into the SEBS matrix, respectively, while the maximum toughness was achieved via SEBS-5H composite with an increase of 45%. The ternary nanocomposite having 3 phr Org-HNT and 10 phr SEBS- g-MA (3H10SMA) gave about a 325% and 103% increase in the elastic modulus and toughness, respectively, together ...

Journal of Composite Materials, 2019

A series of polypropylene (PP)/poly(ethylene- co-vinyl acetate) (EVA) blend nanocomposites was pr... more A series of polypropylene (PP)/poly(ethylene- co-vinyl acetate) (EVA) blend nanocomposites was produced by utilizing different amounts of organophilic halloysite nanotube (Org-HNT) and EVA-based compatibilizers/tougheners. They were prepared by using either only EVA elastomer or using EVA with the compatibilizers which are maleic anhydride grafted EVA (EVA-g-MA) and poly(ethylene-vinyl acetate-carbon monoxide) (EVACO) as well as maleic anhydride grafted PP (PP-g-MA). The morphology–mechanical property relationship was investigated as a function of nature of the compatibilizer and the amount of aluminosilicate nanotube/compatibilizer. The composites prepared without using the EVA-based compatibilizers in all nanotube loading degrees (1%, 3%, 5%) exhibited nanotube aggregates as evidenced by scanning electron microscope analyses. On the other hand, EVA-g-MA and EVACO provided a good dispersion of HNTs at both PP–EVA interface and in the PP matrix. The use of compatibilizers together w...

Polymer International, 2018

Synthesis and characterization of a novel toughener-compatibilizer for polypropylene (PP)-montmor... more Synthesis and characterization of a novel toughener-compatibilizer for polypropylene (PP)-montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride-grafted polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS-g-MA). Special attention was paid to emphasize the effect of PEO-grafted SEBS (SEBS-g-PEO) against SEBS-g-MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X-ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS-g-PEO-containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS-g-MA-containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS-g-PEO toughener-compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating.

Journal of Composite Materials, 2018

Polypropylene (PP)/maleic anhydride grafted polystyrene-b-poly (ethylene/butylene)-b-polystyrene ... more Polypropylene (PP)/maleic anhydride grafted polystyrene-b-poly (ethylene/butylene)-b-polystyrene (SEBS-g-MA)/organophilic halloysite nanotube clay ternary nanocomposites were produced by using HNT/SEBS-g-MA masterbatches at different nanotube loadings (1 wt%, 3 wt%, and 5 wt%). The masterbatches with different ratios of HNT/SEBS-g-MA (1/1, 1/2, and 1/3) were prepared via a revolution/rotation type mixing-assisted masterbatch process. All nanocomposites showed higher storage moduli and damping at low temperatures as compared to neat polypropylene. The nanocomposites having HNT/SEBS-g-MA ratio of 1/3 were found to act as effective dampers with their relatively higher damping values. In terms of short-term creep performance, 1 wt% and 3 wt% organophilic halloysite nanotube loaded systems with low amount of SEBS-g-MA (<9 wt%) enhanced dimensional stability of polypropylene with their lower creep strain and permanent deformation values. More specifically, among the nanocomposites, 3 w...

Clinical oral investigations, Jan 9, 2018

Optical coherence tomography (OCT) is a clinical standard in ophthalmology. Currently, its applic... more Optical coherence tomography (OCT) is a clinical standard in ophthalmology. Currently, its application in dentistry is gaining increasing interest. In this study, we tested the possibility to use a modified commercially available spectral domain OCT (SD-OCT) to assess the layer thickness of orthodontic surface sealants. Reference samples of surface sealants for calibration and repeatability testing were measured using a micrometer screw. SD-OCT measurements were compared with micro-CT and light microscopic analyses. After validating the calibration of the SD-OCT, surface sealant layer thickness after aging (thermo cycling) and simulation of professional tooth cleaning (PTC) was assessed using the SD-OCT on 45 extracted teeth assigned to three test groups (n = 15 each): Light Bond™ Sealant, Pro Seal®, and Opal® Seal. SD-OCT showed excellent repeatability and accuracy for measurements of surface sealant layer thickness. Compared with micro-CT, SD-OCT showed better accordance with the ...

Polymer Engineering & Science, 2017

Styrene/divinyl benzene-based macroporous polyHIPE composites were prepared from water-in-oil (w/... more Styrene/divinyl benzene-based macroporous polyHIPE composites were prepared from water-in-oil (w/o) high internal phase emulsion (HIPE) templates by using both organo-modified montmorillonite (MMT) and a nonionic surfactant. For this purpose, Spirulina (Sp) microalgae was immobilized onto Na-MMT clay by using two different modification techniques. They are based on conventional adsorption in solution (SOL) and novel cryoscopic expansion (C-XP) assisted adsorption. Highly porous nanocomposites were prepared by using different percentages of modified nanoclays (SpSOLM/SpXPM) with a constant internal phase volume of 80%. The emulsion stability, morphology, and dye adsorption capacities were discussed by paying attention to nanoclay immobilization techniques, clay loading degree and surfactant concentration. The critical amount of nonionic surfactant for formation of the stable neat HIPE template was found to be only 5 vol% with respect to volume of organic phase. However, this amount was further reduced to much less value (2 vol%) with Sp immobilized nanoclays via help of cooperative interactions of Sp and MMT nanoclay. The C-XP assisted modification of clay led to nanocomposites with 580% higher adsorption capacity for cationic dye. This remarkable benefit was obtained with even 0.5% clay loading and only 2% surfactant concentration. POLYM.

International Journal of Polymer Science, 2016

As an alternative resin to conventional synthetic unsaturated polyesters (UPEs), epoxidized malei... more As an alternative resin to conventional synthetic unsaturated polyesters (UPEs), epoxidized maleinated castor oil (EMACO) was synthesized in two steps. For this purpose, castor oil was reacted with maleic anhydride at 70°C to obtain maleinated castor oil (MACO). Then, epoxidation of MACO was carried out by using a mixture of formic acid and hydrogen peroxide at 0–5°C. Then, the free carboxyl groups of the synthesized EMACO were further reacted with free epoxide groups of EMACO at 90°C. At the end of the reaction, an unsaturated polyester precursor-prepolymer was obtained (P-EMACO). FTIR and1H NMR spectroscopic techniques were used to characterize the monomers synthesized. The P-EMACO was then mixed with styrene and cross-linked in the presence of AIBN at 50°C. Thermal and mechanical properties of the final cross-linked product were investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The degradation onset temperature of the material at w...

e-Polymers, 2011

Exfoliated and toughened polypropylene nanocomposites prepared by an introduction of a rubber in ... more Exfoliated and toughened polypropylene nanocomposites prepared by an introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene based rubber grafted with maleic anhydride (EPDM-g-MAH) were studied in terms of weld line properties and morphology. Effects of addition of rubber and nanolayer on weld line strength under tensile loading condition of polypropylene matrix were investigated. Data showed that in the absence of either EPDM or nanolayers, a sharp decrease in weld line strength cannot be avoided whereas in the presence of each in optimum ratio, the drastic increase in both toughness and weld line strength values can be easily reached. The beneficial effect is believed to come from the selective placing of nanolayers around the rubber droplets and making them smaller in size which contributes to diffused weld line regions with high mechanical strength.

Journal of Polymer Science Part A: Polymer Chemistry, 2015

INTRODUCTION Polyisobutylene (PIB), one of the best, arguably the best, synthetic rubbery biomate... more INTRODUCTION Polyisobutylene (PIB), one of the best, arguably the best, synthetic rubbery biomaterials, is superbly bio-and hemocompatible, chemically resistant, and sterilizable. 1-3 Further, the PIB molecule can be readily shaped (linear, starshaped, branched, etc.), its molecular weight can be easily controlled from the dimer to many thousands of monomer units, and it can be fitted with a great variety of functional groups. 4,5 And, as the cost of the monomer is rather low (~$ 0.80/lb. as of this writing), the cost of the bundle of properties represented by PIB is relatively low. Some time ago we theorized that homonetworks of 3-arm star-shaped PIBs fitted with terminal cyanoacrylate (CA) groups [Ø(PIB-CA) 3 ], and co-network of Ø(PIB-CA) 3 plus 2-octyl cyanoacrylate (OctCA) could be starting materials for clinically useful flexible topical occlusive wound closure adhesives. Figure 1 shows the structures of these starting materials.

Polymer Composites, 2015

ABSTRACT

Polymer-Plastics Technology and Engineering, 2014

ABSTRACT Polacrylamide nanocomposite hydrogels were prepared by in situ free radical polymerizati... more ABSTRACT Polacrylamide nanocomposite hydrogels were prepared by in situ free radical polymerization reaction in presence of Spirulina microalgae, which is immobilized in montmorillonite clay (Sp-MMT). The nanocomposite hydrogel having 1 wt.% Sp-MMT clay was found to have desired exfoliated structure, maximum swelling and improved thermal stability. It also showed maximum metal adsorption capacity, which is about 312% higher than that of neat PAAm hydrogel at the highest metal concentration. The presence of Spirulina’s porous network structure where all potential binding sites are under receptive position was found to be responsible for the dramatic increase in the metal adsorption and swelling behavior.

Journal of Applied Polymer Science, 2014

Porous polymer composites have been synthesized by polymerizing the continuous phase of styrene/d... more Porous polymer composites have been synthesized by polymerizing the continuous phase of styrene/divinylbenzene high internal phase emulsions in the presence of organophilic montmorillonite clay having a novel oil-based intercalant which is a reactive methacryl derivative of quaternized methyl oleate. The morphological features, thermal stability and mechanical properties, namely compression modulus and crush strength of the resulting composites have been investigated as a function of degree of nanoclay loading. All the composites reinforced with the clay were found to have improved thermal and mechanical properties as well as desired porous and interconnected structural morphology, as compared with the bare polyHIPE matrix. V