Kliničko ispitivanje kompozitnih zalivača fisura

Sistemic fluoride ingestion has been found to be more effective in its caries- reducing benefits on the smooth surfaces than on the pit and fissures. A greater vulnerability to pit and fissure caries determines the need for occlusal surface specific protection. The objective of this study was to investigate clinical effectiveness of 5 different composite sealants during an 18- month observation period. Tested materials were: Superlux Seal-opak (composite with filler particles), Superlux Seal-transparent Estiseal and Fissurit (clear), and Fissurit F (composite with fluoride). They were evaluated according to modified Cvar&Ryge criteria for: retention (R), marginal adaptation (MA), marginal discoloration (MD), surface texture (ST), and secondary caries (SC). The materials were applied in 87 children 6-7 years of age, on 215 first permanent molars, two different materials for each patient. The results were tested for statistical significance by .2 and Fisher's T-test. The results showed good clinical performance of all tested materials with no statistically significant differences. High effectiveness in occlusal caries prevention rated from 97,30% for Fissurit F, and 98% for Superlux Sealopak, to 100% for all other tested sealants. Pit and fissure sealing is an effective prophylactic measure which should be part of the preventive program.Sistemska primena fluorida značajno je doprinela smanjenju incidence karijesa glatkih površina zuba, ali ne i fisura i jamica. Specifičnost okluzalne morfologije zahteva dodatnu profilaktičku meru u vidu zalivanja fisura i jamica specijalno formulisanim materijalima. Cilj ovoga rada bio je ispitivanje kliničke efikasnosti 5 različitih kompozitnih materijala za zalivanje fisura u opservacionom periodu od 18 meseci. Testirani su sledeći materijali, predstavnici tri podvrste kompozitnih zalivača: Superlux Sealopak, (opakni, sa puniocem); Superlux Seal-transparent, Estiseal, i Fissurit (transparentni) i Fissurit F (sa fluorom). Modifikovanim Cvar&Ryge kriterijumima praćeni su retencija (R), marginalna adaptacija (MA), ivična prebojenost (IP,)površinska hrapavost (PH), i pojava sekundarnog karijesa (SK). U ispitivanje je uključeno 87 dece uzrasta 6-7 godina. Svakom pacijentu su na prve stalne molare aplikovana po dva različita materijala na ukupno 215 zuba. Na kraju opservacionog perioda svi testirani materijali pokazali su dobre kliničke osobine bez značajnosti statističkih razlika testiranih.2 i Fisherovim T-testom i visok stepen zaštite od karijesa (od 97,30% za Fissurit F, 98% za Superlux Seal-opak,do 100% za ostale ispitivane materijale). Zalivanje fisura je efikasna profilaktička mera i treba da bude sastavni deo preventivnog programa

Microtensile bond strength of self-etching adhesives to dentin

The aim of this study was to determine micro tensile bond strength of two and one-step self-etching adhesive systems to dentin. 25 intact human third molars were used. Flat surfaces of mid-coronal dentin were exposed and the teeth were divided into 5 groups (n=5). Composite build-ups were made using the following self-etching systems / composite materials: 2-step self-etching system Contax / Ecusphere Carat (DMG), 2-step self-etching system AdheSE / Tetric Ceram (Ivoclar Vivadent), 1-step 2-components self etching system Futurabond NR / Grandio (Voco) and 1-step 1-component self-etching adhesive G Bond / Gradia Direct (GC Corp.). Two-step etch-and-rinse system PQ Clear with Amelogen Universal composite resin (Ultra dent) was used in the control group. Bond strength was assessed with the non-trimming micro tensile technique. Statistical analysis was performed using the 1-way ANOVA, followed by the Tukey test for post-hoc comparisons (p lt 0.05). Investigated self-etching systems showed satisfactory values of micro tensile bond strength to dentin after 24 hours. Two-step self-etching system AdheSE resulted in significantly higher bond strength than all the other groups (p lt 0.001). Micro tensile bond strength of self-etching systems Contax, Futurabond NR and G Bond was comparable to the etch-and-rinse system PQ Clear. .Cilj rada bio je da se odredi jačina veze dvofaznih i jednofaznih samonagrizajućih adhezivnih sistema sa dentinom. Površine dentina su eksponirane na 25 intaktnih trećih molara i zubi su podeljeni u 5 grupa (n=5). Izrađene su kompozitne nadogradnje korišćenjem sledećih samonagrizajućih adheziva / kompozitnih materijala: dvofazni samonagrizajući sistem Contax / Ecusphere Carat (DMG), dvofazni samonagrizajući sistem AdheSE / Tetric Ceram (Ivoclar Vivadent), jednofazni dvokomponentni samonagrizajući sistem Futurabond NR / Grandio (Voco) i jednofazni jednokomponentni samonagrizajući sistem G Bond / Gradia Direct (GC Corp.). Dvofazni adhezivni sistem sa potpunim nagrizanjem PQ Clear sa Amelogen Universal kompozitnim materijalom (Ultradent) korišćen je u kontrolnoj grupi. Jačina veze određena je testom otpornosti mikrouzoraka na kidanje. Rezultati su statistički analizirani jednofaktorskom analizom varijanse (ANOVA) i Tukey testom (p lt 0.05). Ispitivani samonagrizajući sistemi pokazali su zadovoljavajuće vrednosti jačine veze sa dentinom nakon 24 časa. Jačina veze dvofaznog samonagrizajućeg sistema AdheSE bila je značajno viša nego jačina veze u ostalim grupama (p lt 0.001). Jačine veze samonagrizajućih sistema Contax, Futurabond NR i G Bond nisu se statistički značajno razlikovale od jačine veze sistema sa potpunim nagrizanjem PQ Clear.

Prosthetics in paediatric dentistry

Premature loss of teeth in children may lead to both functional and esthetic problems. Missing teeth in both anterior and posterior regions may cause malfunctions in mastication and proper pronunciation. If the missing teeth are not replaced, further complications may occur, including adjacent tooth migration, loss of alveolar bone, and irregular occlusion. Considering the sensitive nature of children, loss of teeth may cause the development of insecurities and low self esteem problems. Due to dynamic nature of growth in children and adolescents, prosthetic appliances must not hinder development of orofacial system, and must meet adequate esthetic and functional standards. Dental prosthetic appliances in paediatrics must be planned with respect to the special conditions that led to tooth loss or damage. Multi-disciplinary approach is needed, under constant supervision of paediatric dentist and orthodontist, as well as regular checkups with clinical and radiographical examinations

Mechanical properties of welded pipes produced by high frequency welding of the steel API J55

Izbor čelika, dimenzija i načina proizvodnje zaštitnih zavarenih cevi je deo procesa konstruisanja, jer je u uskoj vezi sa funkcijom cevi kao konstrukcijske celine u određenim uslovima eksploatacije za predviđeni vek trajanja. Kvalitet zavarenih spojeva u procesu proizvodnje cevi definiše se karakteristikama koje one moraju posedovati da bi zadovoljile određene zahteve, što se postiže izborom odgovarajućih postupaka i parametara zavarivanja, sprovođenjem programa kontrole svih tehnoloških operacija u njihovoj izradi i mehaničkim i tehnološkim ispitivanjima otpornosti i deformacije osnovnog materijala i zavarenih spojeva cevi. U radu su prikazani rezultati ispitivanja mehaničkih osobina uzdužno zavarenih cevi, izrađenih visokofrekventnim kontaktnim zavarivanjem od čelika povećane čvrstoće API J55.Selection of the steel, dimensions and manufacturing methods for protective welded pipes is part of the design process, because it is closely related to the function of tube construction as a whole under certain conditions, for a calculated service life. The quality of welded joints in the process of tubes production is defined by characteristics that they must have to meet certain requirements, which are achieved by choosing appropriate procedures and welding parameters, by controlling all unit operations in their preparation and mechanical and engineering stress and strain tests and base material of welded joints. This paper presents the results of the mechanical properties of longitudinally welded pipes. Casing welded pipe intended for oil and gas wells are made by high frequency contact welding of steel API J55, with increased strength

Kombinovana metoda izrade privremenih mostova

Perfect temporary care guarantees us the complete trust of our patients. From a chemical standpoint Luxatemp or Acrytemp can be classified as bis-acrylic materials. This class of materials has numerous advantages that give us many possibilities for successful clinical use: compatibility with the pulp, lowest setting temperatures, good flexural strength, low shrinkage and high abrasion resistance. The purpose of this paper is to present method of fabrication fixed provisional restorations using a vacuum formed tray matrix with new generation of temporary materials.Adekvatno izrađene privremene nadoknade nam obezbeđuju između ostalog i sticanje pacijentovog poverenja. Luxatemp ili Acrytemp pripadaju grupi bis-akrilatnih kompozita. Ovi materijali imaju brojne prednosti: kompatibilnost sa pulpo-dentinskim kompleksom, nisku temperaturu polimerizacije, dobru otpornost na savijanje, malu kontrakciju i dobru otpornost na abraziju. Cilj ovog rada je bio da prikaže kombinovanu metodu izrade privremenih mostova upotrebom transparentnih plastičnih kalupa u kombinaciji sa novom generacijom materijala za izradu privremenih nadoknada