Search results for "VITRO"
showing 10 items of 2786 documents
In vitro investigation of the impact of remaining tooth structure on the tensile failure loads of overdenture copings
2019
Background The purpose of this in vitro study was to evaluate the impact of the remaining tooth structure on the retention of overdenture cast metal copings. Material and Methods A freshly extracted intact mandibular human canine (length 25 mm) was selected and endodontically treated. An incisal reduction of 4 mm with no ferrule preparation was performed and a post space of 12 mm was created. By using polyvinyl siloxane duplication material and autopolymerizing polymethylmethacrylate resin, ten resin teeth analogs (control group) were obtained. A second set of ten resin teeth analogs (group 1) was created by preparing on the original natural tooth a 360o ferrule design of 1 mm in height and…
Evaluation of accuracy of various impression techniques and impression materials in recording multiple implants placed unilaterally in a partially ed…
2018
Background Various factors like implant angulation, type of impression material and tray type affects the implant impression accuracy. To date limited in-vitro studies were carried out on the implant impression accuracy of unilateral partially edentulous arches. The aim of this research was to evaluate the effects of 0o, 15o and 25o implant angulations on impression accuracy in simulated master casts of unilateral partially edentulous situation using different impression materials and tray selections. Material and Methods 30 replicas (N = 30) of a resin matrix (control) containing four implant analogues placed unilaterally from the midline till the region of second molar at an angulation of…
Comparison of Shaping Ability of 10 Rotary and Reciprocating Systems: an In Vitro Study with AutoCAD
2017
Cilj: Usporediti reznu površinu, očuvanje anatomije korijenskog kanala i neinstrumentiranu površinu nakon instrumentacije sustavima F360®, F6SkyTaper®, HyflexEDM®, iRace®, Neoniti®, O.Shape®, P.Next®, Reciproc®, Revo-S® i WaveOneGold® s veličinom instrumenta 25. Materijali i metode: Tristo zubi s jednim ravnim korijenom i okruglim ili eliptičnim presjekom korijenskog kanala podijeljeno je u 10 skupina (1-F360®, 2-F6SkyTaper®, 3-HyflexEDM®, 4-iRace®, 5-Neoniti®, 6-O Shape®, 7-P.Next®, 8-Reciproc®, 9-Revo-S® i 10-WaveOneGold®) i poprečno prerezano na trećine ultrafinim reznim diskovima. Uzorci su fotografirani pod stereomikroskopom i provedena je predinstrumentacijska analiza prije ponovnog s…
The accuracy of the Raypex5 electronic apex locator using stainless-steel hand K-file versus nickel-titanium rotary Mtwo file
2009
Objectives: Today many clinicians use both stainless-steel hand K-files and nickel- titanium rotary files during endodontic treatment. It is of great importance for the clinician to have confidence in the accuracy of an apex locator even if these files were used interchangeably. The purpose of this in-vitro study was to evaluate the accuracy of the Raypex5 electronic apex locator using stainless-steel hand K-file versus nickel-titanium rotary Mtwo file. Study design: Twenty straight and single canals of maxillary central teeth were used. Access cavities were prepared; actual working length were determined and compared with electronic working length obtained by means of apex locator Raypex5 …
Radiographic Investigation of Location and Angulation of Curvatures in Human Maxillary Incisors
2008
The aim of this radiographic study was to evaluate the degree and location of root canal curvatures of human maxillary incisors. A total of 286 extracted human maxillary incisors (145 central and 141 lateral incisors) were included in this investigation. Exclusion criteria were teeth with extensive carious lesions, restorations, and root canal treatment. For this in vitro study, the teeth were fixed in a special device and digitally x-rayed with the parallel technique. The distances from the cementoenamel junction (CEJ) to the first curvature and the according angle were recorded. The results were analyzed descriptively, and p values were calculated with the Wilcoxon Mann-Whitney test. The …
Association between maxillary and mandibular apical base lengths and severity of dental crowding or spacing in Class II malocclusion subjects: An
2018
Background Anterior crowding/ spacing are one of the major problems that inspire patients to undergo orthodontic treatment. Several factors associated with anterior crowding/ spacing includes arch width and length, mesio-distal tooth diameter and proportions. The aim of the present study was to evaluate the relationship of maxillary and mandibular base lengths to the amount of anterior dental crowding/ spacing in patients with complete class II malocclusions. Material and methods A retrospective study was done with 152 patients who were divided into four groups according to the severity of pre-treatment dental crowding/spacing present in the mandibular arch. Measurements were performed on t…
Influence of the Geometrical Cross-Section Design on the Dynamic Cyclic Fatigue Resistance of NiTi Endodontic Rotary Files—An In Vitro Study
2021
The aim of this study was to analyze and compare the influence of the geometrical cross-section design on the dynamic cyclic fatigue resistance of NiTi endodontic rotary files. Materials and Methods: Forty sterile endodontic rotary files were selected and distributed into the following study groups: A: 25.06 double S-shaped cross-section NiTi alloy endodontic rotary files (Mtwo) (n = 10)
Intramedullary nailing vs. palmar locked plating for unstable dorsally comminuted distal radius fractures: A biomechanical study
2010
Abstract Background The purpose of this study was to compare the stability of a 2.4 mm palmar locking compression plate and a new intramedullary nail-plate-hybrid Targon DR for dorsally comminuted distal radius fractures. Methods An extraarticular 10 mm dorsally open wedge osteotomy was created in 8 pairs of fresh frozen human radii to simulate an AO–A3-fracture. The fractures were stabilized using one of the fixation methods. The specimens were loaded axially with 200 N and dorsal-excentrically with 80 N. 2000 cycles of dynamic loading and axial loading-to-failure were performed. Findings Axial loading revealed that intramedullary osteosynthesis (Targon DR: 369 N/mm) was significantly ( p …
Vesicle formation in the membrane of onion cells (Allium cepa) during rapid osmotic dehydration
2009
BACKGROUND AND AIMS Optimization of osmotic dehydration in different plant cells has been investigated through the variation of parameters such as the nature of the sugar used, the concentration of osmotic solutions and the processing time. In micro-organisms such as the yeast, Saccharomyces cerevisiae, the exposure of a cell to a slow increase in osmotic pressure preserves cell viability after rehydration, while sudden dehydration involves a lower rate of cell viability, which could be due to membrane vesiculation. The aim of this work is to study cytoplasmic vesicle formation in onion epidermal cells (Allium cepa) as a function of the kinetics of osmotic pressure variation in the external…
The Wnt/beta-Catenin Pathway Attenuates Experimental Allergic Airway Disease
2014
Abstract Signaling via the Wnt/β-catenin pathway plays crucial roles in embryogenesis and homeostasis of adult tissues. In the lung, the canonical Wnt/β-catenin pathway has been implicated in remodeling processes, development of emphysema, and fibrosis. However, its relevance for the modulation of allergic responses in the lung remains unclear. Using genetically modified mice with lung-specific inducible (doxycycline) Wnt-1 expression (CCSP-rtTA × tetO-Wnt1), the impact of Wnt on the development of allergic airway disease was analyzed. Overexpression of Wnt during the allergen challenge phase attenuated the development of airway inflammation in an acute model, as well as in a more therapeut…