Sara Yossri Ahmed, Ibrahim Hassan El Kalla And Salwa Mohamad Awad,

ABSTRACT

Objectives: Evaluate The Effect Of Air Abrasion With Different Class III Cavity Restored With Composite On Tensile Failure Load. Method: 40 Extracted Primary Incisors Were Selected Then Mounted In Self-cured Acrylic Resin In PVC Molds. Standard Cavity Preparations Were Prepared. Teeth Were Divided, According To Preparation Technique, Into Four Groups Of 10 Teeth Each. Group A (conventional Class III Cavity), Group B (modified Class III Cavity With 0.5 Mm Labial Bevel), Group C (conventional Class III Cavity With Air Abrasion), Group D (beveled Class III Cavity With Air Abrasion). Group C And D, Treated By An Air Abrasive System Using 50 �m Aluminum Oxide Particles Stream Perpendicularly To The Surface. Then Restored With Composite And St St Wire Was Looped And Embedded In Composite. The Retention Force Were Tested By Universal Testing Machine The Wire Were Grasped With Machine Jigs And Standard Load Will Be Applied Via The Wire To The Restoration At A Head Speed Of 1 Mm/minute Until Restoration Failure.

Results: Comparison Of The Mean Value Observed For All Of The Studied Groups Shows Statistically Significant Difference Between Group A And C (P=0.005), High Significant Difference Between Group A And B (P < 0.001), Between Group A And D (P < 0.001). Group B Shows High Significance Difference With Group C (P<0.001), And Significant Difference With Group D (P=0.002). Group C Shows High Significance Difference With Group D ( P < 0.001). Group D Showed The Highest Mean Tensile Failure Load . Conclusion: Labial Bevel With Air Abrasion Increase Retention Of Class III Composite Restorations.