Mona E. Shabana, Salma H. Al-Ashry And Ahmed M. Ghobashy,

ABSTRACT
Objective: The Aim Of The Current Study Was To Compare Between Rotation Motion (ProTaper Universal And ProTaper Gold) And Reciprocation Motion (WaveOne And WaveOne Gold) In Shaping Ability Of Curved Root Canal By Assessment Of Canal Transportation, Centering Ability And Remaining Dentin Thickness And Changes In Canal Curvature Using CBCT Methods: Forty Extracted Human Mandibular First Molars With Mesiobuccal Canal Curvature Ranged 20-35 Degrees Were Used In The Study. Decoronation Of The Teeth At 15 Mm Length Each Tooth Was Radiographed From The Buccal View With #15 K-file Inside The Mesio-buccal Canal Adjusted To The Apical Foramen Using Vista Scan Digital X-ray Machine And Schneider Angle Was Measured. Teeth Will Be Classified Into Two Main Groups Group I With 20 Teeth For Rotation Motion And Group II For Reciprocation Motion. Each Group Will Be Further Subdivided Into Two Subgroups According To The Type Of File System .Sub Group A For Universal System And Group B For New System. Group I: Ten Teeth Were Shaped Using PU For Subgroup A And Another Ten Teeth Were Shaped Using PTG For Subgroup B According To The Manufacture Instructions And Ending Up To File F2. Group II Subgroup A And Subgroup B Ten Teeth Were Shaped Using Primary WO 25/.07 With X Smart Plus Motor In Subgroup A, Another Ten Teeth Were Shaped Using Primary WOG 25/.08 With X Smart Plus Motor With Wave One Gold Setting In Subgroup B. Both Systems Were Used According To Manufacturer Instruction. Using Cone Beam Computed Tomography With Fused Image, Subtracting The Un-instrumented Dentin From The Instrumented Canal Using On Demand3D Software, Axial Cuts Were Carried Out At 3mm, 5mm And 7mm In The Root. Assessment Of Degree And Direction Of Transportation, Centring Ability And Change In Canal Curvature Was Done Using CBCT. Data Were Collected, Tabulated And Statistically Analyzed In Tables And Figures. Friedman�s Test Was Used To Compare Between The Different Levels Within Each System. Dunn�s Test Was Used For Pair-wise Comparisons When Friedman�s Test Is Significant.

Results: In BL Direction, At 5 Mm Root Level, ProTaper Gold Showed The Statistically Significantly Highest Mean Centering Ratio, While ProTaper Universal Showed The Statistically Significantly Lowest Mean Centering Ratio. There Was No Statistically Significant Difference Between The Four Systems Regarding Change In Canal Curvature Conclusion: The Two Motions Were Comparable As Regards To The Amount Of Dentin Removal, Except At 7 Mm, Reciprocation Revealed Lower Mean Value.As Regards Transportation Direction, The Four Systems Had A Tendency Toward Transportation To The Mesial Direction.Reciprocation Motion Exhibited Superior Performance Compared With The Rotation Motion In Transportation At 7 Mm The Four Different File Systems Straightened Root Canal Curvature Similarly.