GD566 - Effect of immediate vs delayed polishing on the surface roughness of microhybrid and nanohybrid composite resins-GD566

GD566 - Article

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This in vitro study compared the surface roughness of microhybrid and nanohybrid composite resins after immediate polishing or polishing delayed for 24 hours. Researchers prepared 60 disc-shaped specimens—30 of each material—and finished all specimens immediately after curing. Half of each material group was polished at once; the rest were stored in distilled water at 37°C for 24 hours before polishing. Surface roughness (Ra) was measured with a profilometer.<br /><br />Nanohybrid specimens were significantly smoother than microhybrid specimens under both polishing schedules. Mean Ra values were 0.60 μm for immediately polished nanohybrid and 0.53 μm for delayed polishing, compared with 0.76 μm and 0.68 μm, respectively, for microhybrid. For both materials, delayed polishing significantly lowered roughness compared with immediate polishing.<br /><br />The authors suggest that the nanohybrid material’s filler characteristics contribute to better polishability, while the improvement after 24 hours may reflect continued polymerization and maturation of the resin matrix. These findings indicate that, in this laboratory setting, nanohybrid composite and delayed polishing produced the smoothest surfaces.<br /><br />The study was limited to in vitro testing and may not represent clinical conditions such as saliva exposure and chewing. Further clinical research is needed to assess long-term surface performance and confirm the results.

Keywords

microhybrid composite resin

nanohybrid composite resin

surface roughness

polishing delay

in vitro study

profilometer

polymerization

resin matrix

filler characteristics

surface polishability