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ThomasConventional NiTi, Super Elastc NiTi and Beta Titanium arch wires of cross sectional dimension, 0.016 inch,0.016x0.022 inch and 0.017x0.025 inch on two different inter bracket widths of 5 mm and 6.5 mm.MATERIALS & METHODThe sample for the study consists of archwires of different cross section, dimension and composition asgiven in table 1.Table:1 Sample of arch wires for the study.Group No of Sample Composition Dimension Cross Section1a 10 Stainless steel 0.016” round1a 10 Stainless steel 0.016”x0.022” rectangular1c 10 Stainless steel 0.017”x0.025” rectangular2a 10 NiTi 0.016” round2b 10 NiTi 0.016”x0.022” rectangular2c 10 NiTi 0.017”x0.025” rectangular3a 10 Super elastic NiTi 0.016” round3b 10 Super elastic NiTi 0.016”x0.022” rectangular3c 10 Super elastic NiTi 0.017”x0.025” rectangular4a 10 TMA 0.016” round4b 10 TMA 0.016”x0.022” rectangular4c 10 TMA 0.017”x0.025” rectangularAll the wires were from the same manufacturer(Ormco Sybron dental specialities) to minimize thevariation of the mechanical properties due to differentmanufacturing process, chemical composition and heattreatment of the alloy. Samples were divided into12 groups based on composition, cross section anddimension. 30 mm of wire from the distal end ofpreformed arches were utilized for the study. Testswere carried on 5 wires from each group with twodifferent interbracket span of 5 mm and 6.5 mm andthus a total of 120 wires.Acrylic BlockTwo acrylic blocks were fabricated using selfcure acrylic. A cut was made in the 1st block to a depthof 10x10 mm and 13x10 mm in the centre of the 2ndblock to allow deflection. A row of four pre-adjustededgewise stainless steel brackets of Roth prescriptionof manufacturer GAC were embedded on to the acrylicblocks. In first partial acrylic block (Fig:1), 4 bracketswere embedded in position representing both thelower central incisors, canines and 1st premolar, withthe load cell acting as the displaced lateral incisor.The inter bracket width between central incisor andcanine is 10 mm and load cell (acting as lateral incisor)in-between at 5 mm. In second Partial acrylic block(Fig:2), 4 brackets were embedded in the positionsrepresenting both upper central incisors, canines and1st premolar, with the load cell acting as the displacedlateral incisor. The inter bracket width between centralincisor and canine is 13 mm and load cell (acting aslateral incisor) in-between at 6.5 mm.Figure 1: 1st partial acrylic block.Figure 2: 2nd Partial acrylic block.29 Malaysian Dental Journal Jan-Jun 2011 Vol 32 No 1
The Loading And Unloading Properties Of Various Arch Wires As A Function Of Cross Sectional Dimension And Inter Bracket Span WidthModified Three - Point BendingA modified three point bending test enumeratedby Wilkinson was carried out on various wires withan Instron 4500 universal testing machine (Fig:3)fitted with a 100N load cell calibrated on 2 kg rangeand a deflecting rod (Fig:4) of 2mm diameter steelwith a groove. 10 The testing machine was operatedat a crosshead speed of 2 mm/min and the analogueoutput was passed through computer and digitaldisplay.Figure 3: Instron 4500 universal testing machine.The wire was loaded in buccolingual directionin the brackets on flat acrylic block model by elasticmodules. The wires were deflected upto 3 mm in theloading deflection test. The loading and unloadingforce value measured in Newton for all the 120samples were recorded in the computer and subjectedto statistical analysis.Statistical AnalysisThe values tabulated were subjected to analysisof variance. One way ANOVA was used to comparethe mean values between different study groups.Mean, standard deviation and test of significance werecalculated between different types of wires withineach group and enumerated in tables. P value ≤ 0.05denoted the statistical significance.RESULTSFigure 4: Deflecting rod.Loading and unloading of 0.016” arch wires at 5mm and 6.5 mm inter bracket Span.On loading of 0.016 inch wires on deflectionof 1 mm to 3 mm with 5 mm inter bracket width(Graph:1,Table:2). Stainless steel required the highestforce for deflection from 14.54N for 1 mm to 21.9Nfor 3 mm deflection and stainless steel had a lesserforce value (8.6N-15.2N) for 6.5 mm interbracket width(Graph:1,Table:3). Conventional NiTi had force valuesthat were linearly increasing for 5 mm inter bracketspan (2.8N-6.7N) and (2.1N-5.2N) for 6.5 mm interbracket span. Super elastic NiTi had a force value of3.16N on 1 mm and 5.9 N on 3 mm deflection for 5mm inter bracket span. For 6.5 mm inter bracket span,Super elastic NiTi did not linearly progress from 2 mmto 3mm (2.6N-3.6N). For TMA wires the force valuewere (5.0N-12.8N) on deflection of 1 mm to 3 mm.Malaysian Dental Journal Jan-Jun 2011 Vol 32 No 130
Page 2 and 3: Malaysian Dental Journal Editorial
Page 6: Delivery Time Of Orthodontic Applia
Page 9: Delivery Time Of Orthodontic Applia
Page 12: Loke / Tan30-40 appliances a year w
Page 15 and 16: Fracture Resistance Tests Validatio
Page 17 and 18: Fracture Resistance Tests Validatio
Page 19 and 20: An Audit Of The Caseload And Waitin
Page 21 and 22: An Audit Of The Caseload And Waitin
Page 23 and 24: Prosthodontic Considerations In The
Page 29: The Loading And Unloading Propertie
Page 34 and 35: ThomasX axis -- forces in Newton. -
Page 37 and 38: The Loading And Unloading Propertie
Page 43 and 44: Surgical Reconstruction Of The Lost
Page 45 and 46: Surgical Reconstruction Of The Lost
Page 47 and 48: Single Tooth Odontodysplasia- Case
Page 53: Distinguish yourselfGraduate study

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