Hamees Alfred Mohamed , Mona Riad And Safaa Helmy,

ABSTRACT


Aim: The Objective Of This In Vitro Study Was To Evaluate The Effect Of Load Cycling On Fracture Resistance Of A Bioactive Restorative Material And Comparing It With A Zinc Oxide Nanoparticle Containing Bulk Fill Composite

Materials & Methods: A Total Of Fiftyupper Prepared Premolars Were Randomly Divided Into Three Groups. In The Firstgroup 10 Specimens, Cavities Were Remained Unchanged (positive Control). The Remaining 40 Specimens Were Classifiedinto 2 Groups Of 20 Specimens Each According To Types Of Restorative Materials Tested (A); Group (A1) Was Restored By Bioactive Restorative Material, Group (A2) Was Restored By Fill Up Bulk Fillrestorative Material. Each Group Was Subdivided Into 2 Subgroups Of 10 Specimens Each According To The Number Of Load Cycles (T), The Firstsub Group (T1) Was Subjected To Cyclic Loading Representing 24 Hours ( 417 Cycles) And The Second Subgroup (T2) Was Subjected To Cyclic Loading Representing 6 Months (75000 Cycles ). Control Group Also Subjected To The Same Mentioned Cycles. A Mesio-Occluso-Distal (MOD) Cavity Was Prepared In All Specimens. Adhesive System As Well As Resin Composite Application Were Done According To Manufacturer?s Instructions. Mechanical Loading Was Performed Using ROBOTA Chewing Simulator Integrated With Thermo-cyclic Protocol Operated On Servomotor. Data Analysis Was Performed.

Results: Fill Up Bulk Fillcomposite Had The Highest Fracture Resistance Values. There Was A Statistically Significantdifference Between Groups That Subjected To Load Cycled Equivalent To 24 Hours And 6 Months. With All Tested Groups Cycled For 6 Months There Was A Decrease In Fracture Resistance Values.

Conclusions: Fill Up Resin Composite Has The Ability To Withstand The Mechanical And Thermal Loading And Restore The Weakened Tooth Structure Without Fracture More Than Activa. Bioactive Chewing Simulation That Subjects The Restorations To Mechanical Fatigue Has An Influenceon Their Fracture Resistance.