*2.6. Assessment of Surface Micro Roughness (Ra)*

The average surface Ra was calculated in micrometers (μm) using 3D optical noncontact laser profilometry (LPM) (Contour GT-K 3D Optical Microscope, Bruker®, Tucson, AZ, USA). The scanning parameters included magnification of 5× with a lens with a single window of 1 mm × 1 mm, 1× scan speed, and 3% thresholding. The copings were fixed horizontally on the stage using a mold fabricated with impression material (polyvinyl siloxane, 3M ESPE, St. Paul, MN, USA). The laser beam of the optical microscope was placed on the coping surface with the help of stage movement to obtain a good-quality image. The copings were scanned at five location points and an average was identified. To manage the precision and surface roughness parameters, a Vision 64 Control and Analysis Software (Bruker®, Tucson, AZ, USA) was used.
