Comparison on Surface Roughness and Its Effect on Bonding between Conventional Bur and Laser Cut Cavities: An in vitro Study

Buccal surfaces of human extracted molars were obtained and divided into three groups for cavity preparation.Class V cavities were prepared using diamond bur for Group 1, tungsten carbide bur for Group 2, and Er,Cr:YSGG laser for Group 3. The surface roughness was measured using a 3D noncontact profilometer.The samples were subdivided into subgroups A and B, where subgroup B underwent additional acid-etching procedure.The temperature rise during cavity preparation was recorded using a digital thermostat.The samples were then restored with composite resin following application of bonding agent and light cured for 20 seconds for bond strength evaluation under Universal Testing Machine at a cross speed of 0.5 mm/minutes.The data obtained were finally statistically analyzed.On surface roughness evaluation, laser group (G3) produced maximum surface roughness when compared to conventional bur groups (G1 and G2).On depth of surface roughness evaluation, additional acid etching increased surface roughness of all three groups with laser group (subG3B) followed by acid etching exhibiting maximum surface roughness.On bond strength evaluation, diamond group (G1) exhibited increased bond strength when compared to laser (G3) and tungsten carbide group (G2).On thermal change estimation, all the three groups (G1, G2, and G3) produced minimal temperature rise which was below 5.5.Despite increased surface roughness produced by laser, conventional diamond bur (G1) produced highest bond strength when compared to laser (G3) and tungsten carbide groups (G2).