<prompt> Retention grooves are placed with the help of which bur?No.169 LNo.330No.245Tapered fissure  <response>: Retention grooves are prepared with a No.169 L or No.14 round bur with air coolant only to improve visualization and reduced speed to improve tactile feel and control. The bur is placed in the properly positioned axiolingual line angle and directed i.e., translated to bisect the angle approximately parallel to the DEJ. This positions the retention groove 0.2 mm inside the DEJ, maintaining the enamel support. Reference: Sturdevant operative dentistry. 7th edition, Page No:347 