8 research outputs found
Behaviour of flexible/elastic materials under quasi-static force
Elasticity and stress absorption are present in many different materials in our daily life. Understanding how materials behave under pressure (whether that is constant or dynamic), and how and when they deform can be fundamental in terms of their success or longevity. Elastic behaviour is present in many different forms in different materials, e.g.: meats or other food. Interestingly, elasticity is also a major issue in the oral cavity, when talking about healthy dental tissues, such as dentin or even special dental restorative materials. The article focuses on the general mechanical behaviour of elastic and viscoelastic materials and measurements performed on them
Rövid ĂĽvegszál megerĹ‘sĂtĂ©sű kompozit által kifejtett polimerizáciĂłs stressz. ElĹ‘zetes tanulmány [Polymerization shrinkage-stress of short fiber-reinforced composite. Pilot study]
BevezetĂ©s: Kutatásunkban arra kerestĂĽk a választ, hogy kĂ©t eltĂ©rĹ‘ tömĂ©stechnika esetĂ©ben van-e kĂĽlönbsĂ©g a rövidĂĽvegszál megerĹ‘sĂtĂ©sű kompozit (short fiber-reinforced composite, SFRC) tömĹ‘anyag zsugorodása miatt kialakult repedĂ©sekszámában.Anyag Ă©s mĂłdszer: KĂ©t csoportban, 20-20 extrahált bölcsessĂ©gfogba standardizált nagyságĂş MOD ĂĽreget preparáltunk,majd a fogakat az alábbiak szerint restauráltuk SFRC-vel: 1. csoportnál bulk, rĂ©tegzĂ©s nĂ©lkĂĽli technikával, 2. csoportbanpedig ferde rĂ©tegzĂ©ssel 2 mm vastag rĂ©tegekben. Mindegyik minta esetĂ©n az SFRC-t 1 mm kompozittal fedtĂĽk.A tömĂ©s elkĂ©szĂtĂ©sĂ©t követĹ‘en D-Light Pro lámpával megvizsgáltuk a fogzománcot, Ă©s a keletkezett repedĂ©sek számátrögzĂtettĂĽk. Az összrepedĂ©sszámot egy hĂ©t elteltĂ©vel is rögzĂtettĂĽk.EredmĂ©nyek: A kĂ©t tömĂ©stechnika között az eltĂ©rĂ©s nem szignifikáns a repedĂ©sszám tekintetĂ©ben. 1 hĂ©ttel kĂ©sĹ‘bba bulk, rĂ©tegzĂ©s nĂ©lkĂĽli csoportban 4,95 (340%-os növekedĂ©s), a rĂ©tegzĂ©ses csoportban 4,30 (410%-os növekedĂ©s) voltaz átlagos repedĂ©sszám. Ez a korábbi adatokhoz kĂ©pest szignifikáns eltĂ©rĂ©s (p = 0,000). A kĂ©t tömĂ©stechnika közötta vĂ©gsĹ‘ összrepedĂ©sszám tekintetĂ©ben nem tapasztaltunk szignifikáns eltĂ©rĂ©st.KövetkeztetĂ©sek: SFRC anyag esetĂ©n a vizsgált kĂ©t tömĂ©stechnikával közel azonos mĂ©rtĂ©kű repedĂ©skĂ©pzĹ‘dĂ©s jönlĂ©tre, Ă©s mindkĂ©t esetben jelentĹ‘sen megnĹ‘ a repedĂ©sek száma a posztpolimerizáciĂłs idĹ‘szakban
Rövid ĂĽvegszál megerĹ‘sĂtĂ©sű kompozit által kifejtett polimerizáciĂłs stressz. ElĹ‘zetes tanulmány
BevezetĂ©s: Kutatásunkban arra kerestĂĽk a választ, hogy kĂ©t eltĂ©rĹ‘ tömĂ©stechnika esetĂ©ben van-e kĂĽlönbsĂ©g a rövidĂĽvegszál megerĹ‘sĂtĂ©sű kompozit (short fiber-reinforced composite, SFRC) tömĹ‘anyag zsugorodása miatt kialakult repedĂ©sekszámában.Anyag Ă©s mĂłdszer: KĂ©t csoportban, 20-20 extrahált bölcsessĂ©gfogba standardizált nagyságĂş MOD ĂĽreget preparáltunk,majd a fogakat az alábbiak szerint restauráltuk SFRC-vel: 1. csoportnál bulk, rĂ©tegzĂ©s nĂ©lkĂĽli technikával, 2. csoportbanpedig ferde rĂ©tegzĂ©ssel 2 mm vastag rĂ©tegekben. Mindegyik minta esetĂ©n az SFRC-t 1 mm kompozittal fedtĂĽk.A tömĂ©s elkĂ©szĂtĂ©sĂ©t követĹ‘en D-Light Pro lámpával megvizsgáltuk a fogzománcot, Ă©s a keletkezett repedĂ©sek számátrögzĂtettĂĽk. Az összrepedĂ©sszámot egy hĂ©t elteltĂ©vel is rögzĂtettĂĽk.EredmĂ©nyek: A kĂ©t tömĂ©stechnika között az eltĂ©rĂ©s nem szignifikáns a repedĂ©sszám tekintetĂ©ben. 1 hĂ©ttel kĂ©sĹ‘bba bulk, rĂ©tegzĂ©s nĂ©lkĂĽli csoportban 4,95 (340%-os növekedĂ©s), a rĂ©tegzĂ©ses csoportban 4,30 (410%-os növekedĂ©s) voltaz átlagos repedĂ©sszám. Ez a korábbi adatokhoz kĂ©pest szignifikáns eltĂ©rĂ©s (p = 0,000). A kĂ©t tömĂ©stechnika közötta vĂ©gsĹ‘ összrepedĂ©sszám tekintetĂ©ben nem tapasztaltunk szignifikáns eltĂ©rĂ©st.KövetkeztetĂ©sek: SFRC anyag esetĂ©n a vizsgált kĂ©t tömĂ©stechnikával közel azonos mĂ©rtĂ©kű repedĂ©skĂ©pzĹ‘dĂ©s jönlĂ©tre, Ă©s mindkĂ©t esetben jelentĹ‘sen megnĹ‘ a repedĂ©sek száma a posztpolimerizáciĂłs idĹ‘szakban
Behaviour of flexible/elastic materials under quasi-static force
Elasticity and stress absorption are present in many different materials in our daily life. Understanding how materials behave under pressure (whether that is constant or dynamic), and how and when they deform can be fundamental in terms of their success or longevity. Elastic behaviour is present in many different forms in different materials, e.g.: meats or other food. Interestingly, elasticity is also a major issue in the oral cavity, when talking about healthy dental tissues, such as dentin or even special dental restorative materials. The article focuses on the general mechanical behaviour of elastic and viscoelastic materials and measurements performed on them
Crack propensity of different direct restorative procedures in deep MOD cavities
The purpose was to evaluate the crack formation associated with different direct restorative procedures of the utilized resin composites (RC) right after and 1 week later of the restoration.Eighty intact, crack-free third molars with standard MOD cavities were included in this in vitro study and randomly divided into four groups of 20 each. After adhesive treatment, the cavities were restored either with bulk (group 1) or layered (group 2) short-fiber-reinforced resin composites (SFRC); bulk-fill RC (group 3); and layered conventional RC (control). Right after the polymerization and a week later, crack evaluation on the outer surface of the remaining cavity walls was performed with a transillumination method utilizing the D-Light Pro (GC Europe) with the "detection mode." Between- and within-groups comparisons Kruskal-Wallis and Wilcoxon tests were used, respectively.Post-polymerization crack evaluation showed significantly lower crack formation in SFRC groups compared to the control (p<0.001). There was no significant difference within SFRC groups and non-SFRC groups (p=1.00 and p=0.11, respectively). Within group comparison revealed significantly higher number of cracks in all groups after 1 week (p≤0.001), however, only the control group differed significantly from all the other groups (p≤0.003).Post-polymerization shrinkage induced further crack formation in the tooth 1 week after the restoration. SFRC was less prone to shrinkage-related crack formation during the restorative procedure; however, after 1 week, besides SFRC, bulk-fill RC also showed less prone to polymerization shrinkage-related crack formation than layered composite fillings.SRFC can decrease the shrinkage stress-induced crack formation in MOD cavities
Fatigue failure load of immature anterior teeth: influence of different fiber post-core systems
The aim was to explore the fracture-behavior, survival and marginal-microgaps within the root-canal of immature anterior teeth restored with different fiber-reinforced post-core composites (FRCs). 180 bovine-incisors were randomly divided into 6 groups (n=30). One group served as control (group 6). The rest of the teeth were prepared to an internal diameter of 1.6 mm and the apex was sectioned. After application of an MTA-plug, teeth were restored with FRC materials: Group 1: Bioblock technique with short fiber-reinforced composite (SFRC); Group 2: Bioblock technique with flowable SFRC; Group 3: Individually-made FRC post; Group 4: Conventional FRC post; Group 5: dual-cure core build-up composite. After restorations were completed, teeth (n=5/group) were sectioned and then stained. Specimens were viewed under a stereo microscope and the percentage of microgaps within the root-canal was calculated. Fatigue-survival was measured using a cyclic-loading testing machine in the rest of the specimens. Flowable SFRC application in the root-canal (Group 2) did not differ from intact-teeth regarding fatigue-survival (p>0.05). The rest of the groups produced significantly lower survival (p</p
Crack propensity of different direct restorative procedures in deep MOD cavities
The purpose was to evaluate the crack formation associated with different direct restorative procedures of the utilized resin composites (RC) right after and 1 week later of the restoration.Eighty intact, crack-free third molars with standard MOD cavities were included in this in vitro study and randomly divided into four groups of 20 each. After adhesive treatment, the cavities were restored either with bulk (group 1) or layered (group 2) short-fiber-reinforced resin composites (SFRC); bulk-fill RC (group 3); and layered conventional RC (control). Right after the polymerization and a week later, crack evaluation on the outer surface of the remaining cavity walls was performed with a transillumination method utilizing the D-Light Pro (GC Europe) with the "detection mode." Between- and within-groups comparisons Kruskal-Wallis and Wilcoxon tests were used, respectively.Post-polymerization crack evaluation showed significantly lower crack formation in SFRC groups compared to the control (p<0.001). There was no significant difference within SFRC groups and non-SFRC groups (p=1.00 and p=0.11, respectively). Within group comparison revealed significantly higher number of cracks in all groups after 1 week (p≤0.001), however, only the control group differed significantly from all the other groups (p≤0.003).Post-polymerization shrinkage induced further crack formation in the tooth 1 week after the restoration. SFRC was less prone to shrinkage-related crack formation during the restorative procedure; however, after 1 week, besides SFRC, bulk-fill RC also showed less prone to polymerization shrinkage-related crack formation than layered composite fillings.SRFC can decrease the shrinkage stress-induced crack formation in MOD cavities