Effect of highpower light mechanical properties of composites

• Published in: International dental journal Vol. 74; p. S124
• Main Authors: Öztürk, Nur Selen, Demirci, Mustafa, Tuncer, Safa, Tekçe, Neslihan, Duman, Özge
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2024
• ISSN: 0020-6539
• DOI: 10.1016/j.identj.2024.07.950

The intensity and duration of the light curing unit affect the polymerization shrinkage and mechanical properties of composite resins. The aim of the present study was to evaluate the polymerization shrinkage (PS) and Vickers mikrohardness (VHN) of nanohybrid composites. Ten specimens of each nanohybrid composite (Optishade and Sonicfill 3) were prepared. The specimens were shaped in molds (8 mm diamater × 4 mm height and 8 mm diamater × 2 mm height) and cured using an LED curing light unit (Bluephase Powercure,Ivoclar,Vivadent ) at high power plus light curing (1800 mW/cm²) for 8 seconds and standard light curing (1200 mW/cm²) for 10 seconds. VHN test was used to determine the microhardness. The top and bottom surfaces of specimens were polished and microhardness measurements were made on both surfaces. A video imaging device (Acuvol Volumetric Shrinkage Analyzer; Bisco Inc,Schaumburg,IL,USA) was used to measured PS. The PS was calculated as follows: PS = (V₁− V₂) / V₁. The highest VHN was observed for Sonicfill 3 for 2 mm. The bottom/upper ratio of specimens shows values above 80% for the all composite materials. For the high power plus light curing, Optishade were significantly higher (1,85±0,1%) than Sonicfill 3 (1,72±0,08%) for PS measurement. There was no statistical significant difference in PS when using standard curing light. The layer thickness negatively affected the microhardnes of Sonicfill 3. High power plus light curing negatively affected the polymerization shrinkage of Optishade material.