Fluoride as a proteolytic enzyme inhibitor in dentin

Proteolytic degradation of demineralized dentin occurs due to the catalytic activity of dentin matrix-bound matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs). This degradation process takes role in the progression of caries and erosive lesions, as well as the failure of resin-dentin adhesive interfaces. NaF has been previously shown as an effective inhibitor of salivary MMP-2 and -9. Therefore, in this thesis, NaF, KF and CaF2 were systematically screened to investigate the efficacy of fluoride on the inhibition of dentin matrix-bound MMPs and CCs in order to prevent the collagenolytic breakdown of demineralized dentin matrices, and to improve the stability of adhesive interfaces. Degradation of demineralized dentin subjected to NaF, KF and CaF2 with a wide range of concentrations has been systematically screened using total MMP activity assay, gelatin zymography, dry mass loss and the quantitative measurements of collagen degradation products involving ICTP, CTX and hydroxyproline, and scanning electron microscopy analysis. Bonding stability to phosphoric acid-etched and NaF, KF and CaF2 treated dentin surface was examined by a microtensile strength test set-up. According to the results, NaF, KF, or CaF2 did not prevent the MMP-dependent degradation of demineralized dentin. High levels of NaF and KF was effective in the long-term inhibition of dentin matrix-bound CCs. However, since MMPs are the major enzyme groups responsible from the collagen degradation in dentin, only CCinhibition was not sufficient for the prevention of demineralized dentin degradation. NaF and KF treatment of acid-etched dentin surface might be beneficial for the durability of resin-dentin adhesive interfaces by slowing down the breakdown of insufficiently resin infiltrated collagen fibrils, probably via silencing MMPs and CCs.Fluoridi proteolyyttisten entsyymien inhibiittorina dentiinissä Demineralisoituneen dentiinin proteolyyttinen hajoaminen tapahtuu dentiinin orgaaniseen matriksiin sitoutuneiden entsyymien, matriksin metalloproteinaasien (MMP) ja kysteiini katepsiinien (CC) toimesta. Tämä hajoaminen vaikuttaa kariesleesion ja eroosion etenemiseen, kuten myös hampaan ja paikka-aineen sidosaineen liitospinnan heikkenemiseen. NaF:n on aikaisemmin osoitettu estävän tehokkaasti syljen MMP-2:n ja MMP-9:n aktiivisuutta. Tässä väitöskirjatyössä kartoitettiin systemaattisesti NaF:n, KF:n ja CaF2:n dentiinimatriksin MMP- ja CCestovaikutusta, tavoitteina demineralisoituneen matriksin hajoamisen estäminen ja paikka-hammasliitoksen stabiloiminen. Lukuisilla eri NaF-, KF- ja CaF2-pitoisuuksilla käsitellyn demineralisoidun dentiinin hajoamista tarkasteltiin monipuolisesti käyttäen totaali-MMP-aktiivisuusanalyysiä, gelatiinizymografiaa, kuivamassakatoa, kollageenin hajoamistuotteiden ICTP-, CTX- ja hydroksiproliinimittauksia sekä elektronimikroskopiaa. Happoetsatun ja NaF-, KF- ja CaF2-käsitellyn dentiinin sidoslujuuden stabiilisuutta tutkittiin mikrovetolujuusmenetelmällä. Tulokset osoittivat, että NaF, KF tai CaF2 eivät estäneet MMP:ien aiheuttamaa demineralisoituneen dentiinin hajoamista. Korkeat NaF- ja KF-pitoisuudet estivät pitkäaikaisesti dentiinimatriksiin sitoutuneita CC:ja. Koska MMP:t ovat kuitenkin pääasiassa vastuussa dentiinimatriksin hajoamisesta, pelkkä CC-esto ei riittänyt estämään matriksin hajoamista. NaF- ja KF-käsittely voisi kuitenkin parantaa hampaan ja paikkamateriaalin liitosaluetta hidastamalla epätäydellisesti resiiniinfiltroituneen kollageenin hajoamista, mahdollisesti MMP- ja CC-eston kautta

The comparative study of reading comprehension achievement between students with extrovert and introvert personality at SMAN 1 Bandarlampung

Abstract.The objectives of this research is to find out whether there is any significant difference of students’ reading comprehension achievement between students with extrovert and introvert personality. The population of the research was the students of the first grade of SMAN 1 Bandar Lampung in the academic year 2019/2020 totally 287 students. The sample of this research was X MIA 2 consisting of 35 students.The result showed that there was difference between the mean score of extrovert students (78.2) and that introvert students (72.5). The researcher used 0.05 significant level in SPSS 16 to do the calculation. The result showed that the Sig. (2 - tailed) is 0.001 0.05. Due to the value of Sig. (2 tailed) is lower than 0.05, it means there is a significant difference between introvert students’ reading comprehension ability and extrovert students. Based on the result of the research, it is proved that the extrovert students have better result than introvert one in reading comprehension test. So, from this statement the researcher’s hypothesis (Hi) is accepted

EFFECTS OF THERMOCYCLING AND VARIOUS DRINKS ON THE COLOR STABILITY OF HEAT-POLYMERIZED ACRYLIC RESIN

Purpose: The discoloration of acrylic resin denture bases may lead to significant esthetic problems. The aim of this in vitro study was to investigate the effects of frequently consumed drinks on the color changes of fresh and aged, heat-polymerized, conventional acrylic resin.Materials and Methods: Eighty-four, heat-polymerized acrylic resin specimens (4 mm x 5 mm x 30 mm) were fabricated. Half of the specimens were aged by thermal cycling (between 5 degrees C and 55 degrees C, 60-second dwell time, 3000 cycles). The specimens were stored at 37 degrees C in different drinks as non-aged and aged subgroups including water (control group), black tea, green tea, sour cherry juice, coke and coffee (n=7). The discoloration of each specimen after 1 and 7 days storage in the drinks were measured by a colorimeter based on CIE Lab system. The data of colour differences (Delta E) were analyzed by ANOVA and Dunnet's tests.Results: Thermal cycling and storage in water induced a slight color change. The highest DE values were observed in the aged groups, which was also noticeable for black tea and sour cherry juice after 7 days of storage (Delta E>1.5) (p<0.05). The Delta E values of all test groups were detected within the acceptable clinical limits (Delta E<3.5).Conclusion: These results suggest that the color stability of denture base acrylic resins is influenced by ageing. Black tea, sour cherry juice and coke can cause significant discolorations on acrylic resin denture bases

Microtensile bond strength to phosphoric acid-etched dentin treated with NaF, KF and CaF2

Purpose: Fluoride compounds have been reported to play a protective role in the host-derived enzymatic degradation of demineralized dentin matrices. The objective of this study was to evaluate the effect of fluoride pretreatment on the immediate and long-term microtensile bond strength (mu TBS) of resin-dentin interfaces. Materials and methods: Mid-coronal dentin surfaces of ninety-nine teeth were etched with 32%wt phosphoric acid and randomly assigned to pretreatment with NaF, KF or CaF2 solutions (6, 24 and 179 mM F content) for 30 s before the application of bonding agent (Scothbond Multi-Purpose, 3 M ESPE). No fluoride pretreatment and a commercially available bonding agent with KF (Excite F, Ivoclar Vivadent) were used as controls. After composite built-up, the specimens were sectioned into TBS test beams, stored in artificial saliva at 37 degrees C for 24 h, 6 or 12 months and tested. Fracture types were evaluated under scanning electron microscope. The data were analyzed with ANOVA and Scheffe post-hoc tests (alpha = 0.05). Pearson Chi-Square test was used to compare the distribution of failure types. Results: Fluoride compound, fluoride concentration and storage time showed significant effect on TBS (p 0.05), except CaF2 179 mM (p <0.05). According to Chi-square test, fracture types were also significantly influenced from the test factors (p <0.05). Conclusions: NaF and KF treatment after acid-etching step of adhesive bonding procedures do not adversely influence the initial or long-term bond strength to dentin, and can improve the maintenance of bond strength durability.Peer reviewe

Repair bond strength of nanohybrid composite resins with a universal adhesive

Objective: To investigate the repair bond strength of fresh and aged nanohybrid and hybrid composite resins using a universal adhesive (UA).Materials and methods: Fresh and aged substrates were prepared using two nanohybrid (Venus Pearl, Heraus Kulzer; Filtek Supreme XTE, 3 M ESPE) and one hybrid (Z100, 3 M ESPE) composite resin, and randomly assigned to different surface treatments: (1) no treatment (control), (2) surface roughening with 320-grit (SR), (3) SR + UA (iBOND, Heraus Kulzer), (4) SR + Silane (Signum, Ceramic Bond I, Heraeus Kulzer) + UA, (5) SR + Sandblasting (CoJet, 3 M ESPE) + Silane + UA. After surface treatment, fresh composite resin was added to the substrates at 2 mm layer increments to a height of 5 mm, and light cured. Restored specimens were water-stored for 24 h and sectioned to obtain 1.0 × 1.0 mm beams (n = 12), and were either water-stored for 24 h at 37 °C, or water-stored for 24 h, and then thermocycled for 6000 cycles before microtensile bond strength (µTBS) testing. Data were analyzed with ANOVA and Tukey’s HSD tests (p = .05).Results: Combined treatment of SR, sandblasting, silane and UA provided repair bond strength values comparable to the cohesive strength of each tested resin material (p p Conclusions: Universal adhesive application is a reliable method for composite repair. Sandblasting and silane application slightly increases the repair strength for all substrate types.</p

Effect of calcium fluoride on the activity of dentin matrix-bound enzymes

Objective: Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) are two distinct enzymatic pathways responsible for the degradation of collagen fibrils in demineralized dentin. NaF and KF have been shown to inhibit salivary MMP-2, -9 and CCs. This study investigated the inhibitory effect of calcium fluoride (CaF2) on the dentin matrix-bound MMPs and CCs. Design: Phosphoric acid (10%)-demineralized dentin beams (1 x 2 x 6 mm) were incubated at 37 degrees C in an 1 ml of artificial saliva (AS, control), or AS with 6, 12, 24, 48, 120. 179 and 238 mM F containing CaF2 (n = 10/group) for 1, 7 and 21 days. All groups were further incubated in AS only for 6 months. Total MMP activity, dry mass loss, CTX and hydroxyproline (HYP) analyses were performed after each incubation. The beams were examined under scanning electron microscopy (SEM). MMP-2 and MMP-9 activities were screened with gelatin zymography. Data were analyzed by using ANOVA and Tukey HSD tests (p = .05). Results: The total MMP activity was similar for all groups after 21 days and 6 months. After 21 days, the cumulative mass loss and CTX levels were lower compared to control for the CaF2 48 and CaF2 120 mM, respectively (p .05), whereas HYP level was higher with F 24 and 238 mM groups. CaF2-like minerals were observed on the beams under SEM. There was no gelatinase inhibition in zymography. Conclusion: CaF2 does not prevent the degradation of demineralized dentin matrices due to the catalytic activity of MMPs and CCs.Peer reviewe

FAIR Metadata Standards for Low Carbon Energy Research—A Review of Practices and How to Advance

The principles of Findability, Accessibility, Interoperability, and Reusability (FAIR) have been put forward to guide optimal sharing of data. The potential for industrial and social innovation is vast. Domain-specific metadata standards are crucial in this context, but are widely missing in the energy sector. This report provides a collaborative response from the low carbon energy research community for addressing the necessity of advancing FAIR metadata standards. We review and test existing metadata practices in the domain based on a series of community workshops. We reflect the perspectives of energy data stakeholders. The outcome is reported in terms of challenges and elicits recommendations for advancing FAIR metadata standards in the energy domain across a broad spectrum of stakeholders

Store Modellıng Of Flammable, Combustıble And Explosıve Materıals

Dünyada ve ülkemizde, parlayıcı, patlayıcı sıvı ve gazların depolanmasında gerekli ve yeterli önlemler alınmazsa, patlamaların sebep olduğu mal ve can kayıpları artacaktır. Bu patlamalar, yakıt tanklarının alev alması, LPG taşıyıcı tanker patlamaları, petrol boru hatlarında meydana gelen felaketler şeklinde ortaya çıkmaktadır. Ancak, patlama üçgeni olarak adlandırılan alev alabilen madde, oksijen (hava) ve ateş kaynağının aynı anda bir arada bulunmaması halinde patlama meydana gelmemektedir. Bu sebeple, bu girdilerden birinin ortamdan uzak tutulması, bu tip felaketlerin oluşmasını engellemek için bir anahtar halindedir. Bu amaçla, bu tez çalışmasında, depo içinin alüminyum yüzük veya perfore edilmiş küreler ile doldurulması veya depo iç çeperinin, kaplama malzemesi ile 3600 kaplanması şeklinde depo modelleme sistemleri irdelenmektedir. İkinci sistem ancak depo imalatı sırasında uygulanabildiğinden, mevcut depolara uygulanması mümkün olmadığından ve kullanılan depoların değiştirilmesi ve ciddi bir maliyet oluşturması sebepleriyle birinci depo modelleme sistemine odaklanılmıştır. Standart depolar ile modellenen depolardaki yakıtların laboratuvar testleri yapılmıştır. Bu testlere ilaveten depolara uygulanan test ve analizlerde, depolarda BLEVE oluşması için yakıt buharı ile dolu tankere G 3 tüfeği 7,62x51 kalibre mermiyle ateş edilmiş, UEL ve LEL değerleri arasında kalacak şekilde yakıt doldurulmuş depo jet taşı ile kesilmiş, oksijen kaynağı ile doldurulmuş ve yangın ortamında bırakılmıştır. Depo modelleme sistemi 1 ile gerçekleşmesi beklenen BLEVE patlaması engellenmiştir. Ayrıca, taşıma sırasında yakıtın depo içinde çalkalanmasıyla tankerlerde denge sorunu yaratan ve işletme hızını düşüren olumsuzluklar depo modelleme sistemiyle minimuma indirilmektedir. Böylece, yakıt tankerlerinin şehir içi 30 km/saat, şehirlerarası 50 km/saat ve otoyollarda 60 km/saat olan seyir hızı artırılabilmektedir.It is very clear that, if the necessary precautions are not taken about the storage conditions of flammable and explosive liquids and gases, it will cause disasters such as explosion of a pressure vessel or from natural gas, solvent, fuel station, air craft accidents and oil transfer lines. When those events are examined, it is obvious that there will be no explosion if any of the flammable material, oxygen (air) and ignition source is absent. Keeping one of those inputs away is the key to prevent those kinds of disasters. There are two storage modeling systems: filling the storage with rolls of aluminum and coating the inner wall of the storage with 3600 coating material. Coating at the second system is not possible or applicable for existing or currently used tanks unless it is made during manufacture. Therefore, the former system of storage modelling is focused in this study. In addition to laboratory tests of fuels stored, tank filled with fuel was shot by G 3 rifle 7,62x51 calibre bullets, fuel tank was cut by abrasive wheel and the cut is welded with a source of oxygen successively in order to generate BLEVE explosion,. It is demonstrated that the tank filled with fuel to ensure that the values remain between LEL and UEL subjected to fire environment. This storage modeling system has prevented the realization of the expected explosion BLEVE at all tests and analyzes. Moreover turbulance in the tank while transporting creates balance problems and reduces the operating speed of the tanker can be minimized by this modelling. Thus fuel tankerzs operating speed which is 30 km/hr in urban, 50 km/hr in long distance and 60 km/hr in motorways can be increased