Ahmed Mohamed Hamed Khalaf*, Ahmed Emad Fayyad** And Maha Wagdy Elkerdawy***,

ABSTRACT


Aim: The Aim Of This In-vitro Study Was To Evaluate The Fracture Pattern And Strength Of Temporary Fixed Dentures Made FromAcetal On Four Mandibular Implants Compared To PMMA.Methodology: The Present Study Was Conducted On 6 Temporary Fixeddentures Made From Same Design On CAD Software By Milling From Acetal And PMMA Blocks; 3 From Each Group. These Fixeddentures Were Cemented On The Same Mandibular Model Containing 4 Implants Alternatively. Each Fixedrestoration Was Tested By Applying Load From A Universal Testing Machine Using A T Shaped Load Applicator At Cross-head Speed Of 5mm/min. The Load At Failure Manifested By An Audible Crack And Confirmedby Sharp Drop At Load-deflectioncurve Recorded Using The Computer Software. The Load Required To Fracture Was Recorded In Newton. All These Parameters Were Subjected To Statistical Analysis.

Results: The Highest Mean Value Was Found In (Acetal) (5366.67 ? 10.69)N, The Lowest Mean Value Was Found In (PMMA) (1128.00?13.89)N With A Statistical Significantdifference Between The 2 Groups. Also The Fracture Pattern In The PMMA Group Was More Extensive.

Conclusions: Acetal Showed To Be Stronger And Withstood Higher Stress Than The PMMA When Used At The Cantilevered Part Of The Prosthesis With More Favorable Pattern Of Failure.