Scanning electron microscopic analysis of the sealing ability of GuttaFlow and Acroseal endodontic sealers

Introduction: The sealing ability of endodontic sealers to dentinal surfaces of root canals is an important feature of these materials. Root canal sealers are necessary to seal the spaces between the dentinal walls and the obturating core material. Aim: The aim of this study was to examine the sealing ability of two endodontic sealers to dentin walls and guttapercha cones using scanning electron microscopic analysis-SEM. Materials and Methods: 24 recently extracted human single-rooted teeth were instrumented and allocated to two groups; root canals were filled with either GuttaFlow (Roeko,Germany), a new endo-sealer (group 1), or Acroseal (Septodont, France), a calcium hydroxide based sealer, (group 2). The sealing ability and adhesion properties of the sealer-dentin interface were studied using SEM. Results: The specimens filled with GuttaFlow showed smooth contact lines at the sealer-dentin interface, and this material also showed strong bonding and good adaptation to guttapercha cones. Acroseal showed good adhesion to dentin walls, and bonding surface was represented as a slightly curved contact line, with some gaps on material-dentin walls and guttapercha cones interface. Conclusion: New GuttaFlow material possesses strong sealing ability and excellent adhesion to dentin walls and guttapercha cones. Acroseal showed good bonding to dentin and slightly weaker adhesion to guttapercha cones, in comparison to GuttaFlow

Uticaj doze na prolaz fluorida kroz placentu u kunića

Placental transfer of fluoride was investigated by fluoride determination in the bones and teeth of newborn rabbits whose mothers had been treated with fluoride during pregnancy. The mothers were given doses of 0, 0.10, 0.52 and 1.05 mmol fluoride per kg body weight as sodium fluoride, from the 16th day after conception to the end of pregnancy. All the doses produced a significant increase of fluoride level in the bones and teeth of newborn rabbits, indicating that the placenta was no barrier for the passage of fluoride.Prolaz fluorida kroz placentu ispitivan je određivanjem koncentracije fluorida u kostima i zubima mladunaca gravidnih ženki kunića tretiranih fluoridima. Primenjene su doze 0, 0,10, 0,52 i 1,05 mmol F- /kg telesne mase u obliku vodenog rastvora natrijum-fluorida, od 16. dana posle začeća do kraja graviditeta. Pri svim ispitivanim dozama dolazi do porasta koncentracije fluorida u kostima i zubima mladunaca, što pokazuje da placenta ne predstavlja barijeru za prolaz fluorida

Impact of the geographic factors on the transport of lead and cadmium in the air

The aim of this study is to describe the effect of geographical varieties on the transport of lead and cadmium in the air. During period between 1997- 2006, the concentrations of lead in suspended in the air at 5 measuring sites in Serbia were measured. The minimal measured daily concentrations of lead ranged from 0,42 μg/m3 (2002.) in Kraljevo. The maximal measured daily concentrations of lead to 251,8 μg/m3 (2004.) in Belgrade. During the period between 1997-2006., the concentrations of cadmium in suspended in the air at 5 measuring sites in Serbia were measured. The minimal measured daily concentrations of cadmium ranged from 0,1 μg/m3 (1999) in Kraljevo. The maximal measured daily concentrations of lead to 42,0 μg/m3 (2000) in Belgrade. Results from our experiments demonstrated that when rapid infiltration conditions or a rainstorm exist, particle-facilitated transport of contaminants is likely to the dominant metal transport pathway influenced by acid rain.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Application of Generalized Taper Model of Norway Spruce Tree in Forestry Practice

U radu je prikazan jedinstveni model oblika debla smreke, razvijen primjenom modificirane Brinkove funkcije, za područje Bosne i zapadne Srbije. Cilj istraživanja je izvršiti prilagođavanje jedinstvenih modela (Model 1 i Model 2) oblika debla prikazanih u radu Matovića, i dr.(2007) za jednostavnu praktičnu primjenu u šumarstvu. Jedinstveni model dobiven u ovome radu (Model 3) pokazuje nešto manju preciznost procjene promjera duž debla i volumena stabla od jedinstvenih Modela 1 i 2, ali je još uvijek dovoljno precizan, pa se uspješno može rabiti u šumarskoj praksi. U radu je izvršeno i uspoređenje jedinstvenih modela oblika debla s klasičnim dvoulaznim volumnim tablicama. Model 3 ima značajnu praktičnu primjenu i može se koristiti za procjenu volumena cijelog ili dijelova debla, promjera na bilo kojemu dijelu debla i neposredno visina stabla na kojima se nalaze karakteristični (traženi) promjeri.By applying modified Brink’s function, this paper presents the unique generalized taper model of Norway spruce tree, developed for the area of Bosnia and west Serbia. The objective of this research is adapt generalized taper models (Models 1 and 2) for trees presented in the paper Matović, et al. (2007), for practical use in forestry. The significant quality of the modified Brink’s function is the correlation of the characteristics of individual trees and stands and the function parameters, so in this way generalized taper models can be calculated for the use in a definite geographic region. The study of Norway spruce taper is based on the data collected from 86 even-aged stands in the region of Bosnia and west Serbia, which is adjacent to Bosnia. The total number of model trees is 156, and the number of data pairs (diameter-height) is 2028. The original parameters i, p and q of the modified Brink’s function were first calculated for all model trees by the optimisation method - equations (1). By applying the multiple regression method, a link has been established between original values of parameters i, p and q, and characteristics of individual trees (diameter at breast height and tree height), i.e. Model 3 has been obtained. Model 3 is consisted of three functions used for determining the parameters of generalized taper model i, p and q. Unknown parameters of the three functions a1, a2, a3,...,.a15 are determined on the basis of available data, by applying multiple regression – equations (2), (3) and (4). In order to test the estimation of taper volume, on the material used for the development of generalized taper models of spruce trees by applying multiple regression, dual input volume tables were created. For that purpose Näslund and Schumacher-Hall functions were used – equations (6) and (7). This research confirms that Model 3 shows less accuracy in estimating the diameter along the taper and volume than Models 1 and 2, which besides using the diameter at breast height and tree height, also require using the stand quadratic mean diameter. However, such difference, from the aspect of practical use, is not important, so Model 3 that applies only the diameter at breast height and tree height (in fact, reduced to the level of dual input volume tables) can be successfully used in forestry practice. Obtained Model 3 is the superior substitute for conventional dual input volume tables, because besides the total volume it enables the volume estimation for particular parts of the standing tree, and also estimation of the diameter along the taper. Model 3 indirectly enables the calculation of tree heights with some diameters characteristic for forestry practice. Model 3, with all above mentioned practical possibilities, can be very simply used by applying one EXCEL application. Because of the dimensions of trees used for Model 3 design, it can be reliably used in practice for Norway spruce trees with diameters at breast height of 10 to 60 cm and height of 6 to 37 m

Ispitivanje kvaliteta opturacije kanala korena zuba metodom gasne propustljivosti

Introduction. Prognosis of root canal treatment is highly dependent on the quality of endodontic space obturation. The main task of successful root canal treatment is to achieve adequate reparation processes in the apical periodontium. The aim of this study was to evaluate the quality of root canal obturation using the method of gas (argon) penetration through three different endodontic materials. Material and Methods. Thirty recently extracted human single-rooted teeth after root canal instrumentation were divided into three identical groups and obturated with three different endodontic materials: group I - GuttaFlow (RSA, Germany), group II - AH Plus (DeTray, Germany), group III - Acroseal (Septodont, France). The quality of root canal obturation was evaluated using the method of gas permeability. Results. The best results were obtained with GuttaFlow. The average penetration rate of argon was 186.7 seconds. Slightly higher gas porosity had AH Plus, 179.9 seconds, while the highest gas permeability was observed after the application of Acroseal, 178.5 seconds. However, there was no statistically significant difference in gas penetration among these endodontic materials (p>0.05). Conclusion. All three endodontic materials showed gas permeability in a given time interval. The best quality of obturation was achieved with GuttaFlow, while the lowest quality was obtained with Acroseal.Uvod. Prognoza lečenja kanala korena zuba umnogome zavisi od kvaliteta opturacije endodontskog prostora. Uspešno izvedeno endodontsko lečenje omogućava i stimuliše odgovarajuće reparacijske procese u apikalnom periodoncijumu, što je osnovni zadatak svakog lečenja kanala korena zuba. Cilj ovog rada je bio da se metodom merenja prodora gasa (argon) kroz tri različita endodontska materijala utvrdi i uporedi dobijeni kvalitet opturacije kanala korena zuba. Materijal i metode rada. Trideset sveže ekstrahovanih jednokanalnih humanih zuba je nakon endodontske instrumentacije svrstano u tri identične grupe, nakon čega su opturisani primenom tri različita endodontska materijala: I grupa - GuttaFlow (Roeko, Nemačka), II grupa - AH Plus (DeTray, Nemačka), III grupa - Acroseal (Septodont, Francuska). Kvalitet dobijene opturacije kanala korena zuba ispitivan je metodom merenja gasne propustljivosti. Rezultati. Najbolje rezultate pokazao je endodontski materijal GuttaFlow, sa prosečnom brzinom prodora gasa argona od 186,7 sekundi. Nešto veću gasnu poroznost imala je pasta AH Plus, 179,9 sekundi, dok je najveća gasna propustljivost uočena nakon primene paste Acroseal - 178,5 sekundi. Međutim, između samih endodontskih materijala nije utvrđena statistički značajna razlika u brzini propuštanja gasa (p>0,05). Zaključak. Dobijeni rezultati su pokazali da je kod sva tri endodontska materijala došlo do propuštanja gasa argona u određenom vremenskom intervalu. Najbolji kvalitet opturacije ostvaren je primenom GuttaFlow, dok je najslabiji rezultat dobijen nakon primene paste Acroseal

Sintetičke studije analoga paklitaksela sa modifikovanim D-prstenom

A synthetic sequence has been developed for the preparation of 9,10-di-O-diacetyl-4-desmethylene-4 beta-(3-butenyl)-4 alpha-hydroxy-5-O-mesyltaxicin I-1,2-carbonate 3, an intermediate in an attempted synthesis of a cyclobutane paclitaxel analogue. A series of reactions of 3 were investigated, including the protection of the sterically hindered C-4 alpha-hydroxy group and the oxidative cleavage of the terminal double bond. Cyclization of 13 to the cyclobutane-containing intermediate failed due to the unexpected instability of the dimethylsilane protecting group under basic conditions.Razvijena je sintetička sekvenca za dobijanje 9,10-di-O-acetil-4-desmetilen-4β-(3-butenil)-4α-hidroksi-5-O-meziltaksicin I-1,2-karbonata (3), intermedijera u pokušanoj sintezi ciklobutanskog analoga paklitaksela. Ispitivana je mogućnost dalje hemijske transformacije jedinjenja 3, kao što je zaštita sterno izrazito zaštićene C-4α hidroksilne grupe i oksidativna fragmentacija terminalne dvostruke veze. Ciklizacija jedinjenja 13 nije dala željeni rezultat - intermedijer sa ciklobutanovim prstenom, što je posledica neočekivane nestabilnosti DMS-zaštitne grupe u baznim reakcionim uslovima