Shrinkage Stresses of Several Light Cured Resin-based Composites

Objectives: New universal and flowable resin based composite have been used for a few decades. However, with more demand of bulk fill, the shrinkage stress is still a concern in restoration longevity.
Methods: Eleven composite resins, seven flowable composites, 1) Filtek Supreme Ultra Flowable Restorative (3M ESPE), 2) NOVAPRO Flow (Nanova Biomaterials), 3) SureFil SDR Flow (DENTSPLY Caulk), 4) G-ænial Universal Flo (GC America), 5) Herculite Ultra Flow (KERR Restoratives), 6) Dentex Flow, (Dentex Dental Materials), and 7) Prime Dent flowable (Prime Dental), and four universal composites 8) Filtek Supreme Ultra Universal (3M ESPE), 9) Beautifil II Universal (Shofu Dental), 10) NOVAPRO Fill Universal (Nanova Biomaterials), and 11) Herculite Ultra Universal (KERR Restoratives) were tested in this study.
Two fused silica glass rods with flat surfaces were used to make a composite resin cylinder of 5mm in diameter and 1mm in height. The rod ends were roughened with 100 grit sand paper and treated with bonding agent Optibond Solo Plus and light cured. The two rods were fixed vertically with two chucks attached to a universal testing machine (INSTRON 5566A). Tested composite resins were injected into the cylindrical gap and carefully shaped, then uniformly cured for 20s. The contraction load during polymerization were recorded by attached 100N load cell in Bluehill 3 software. Peak load was acquired at 5 mins after the curing light stopped and calculated into shrinkage stress. One-way ANOVA post hoc Tukey HST (JMP Pro 12.0.) was used for analyze the difference of shrinkage stresses among groups (significance level = 0.05).
Results: The shrinkage stress results are shown in Table 1 below.
Conclusions: Tested composites showed significant different shrinkage stress during polymerization. In general flowable composite showed higher shrinkage stresses than universal composite. Surefil showed the lowest shrinkage stress.