title: [Efficacy of flowable composite resin as stress-absorbing liners in Class I cavity restorations].
abstract: OBJECTIVE
  To evaluate the efficacy of flowable composite resin(FCR) as stress-absorbing liners in Class I cavity restorations in vitro.
  
  
  METHODS
  Thirty Class I cavities of 4 mm in diameter and 2 mm in depth were prepared in polycarbonate (PC) plates and divided into three groups, ten each. After application of an adhesive, cavities in each group were restored using one of the following methods: A: restored with Charisma without any lining of FCR; B: lined with Revolution Formula 2 twice before restoration with Charisma; C: lined with Teric Flow twice before restoration with Charisma. All cavities were observed under a photoelastic microscope and photoelastic images were recorded at 3 min and 24 h after curing and the shrinkage stresses on the cavity wall were calculated. The polymerization shrinkage(v%) of the three composite resins was measured using bonded discs method and their elastic moduli were measured according to ISO standard.
  
  
  RESULTS
  The shrinkage stresses at 3 min and 24 h of the three methods were as follows,A: (4.93 ± 0.28), (5.87 ± 0.40) MPa, B: (4.90 ± 0.30), (5.84 ± 0.33) MPa, and C: (4.76 ± 0.28),(5.83 ± 0.37) MPa.No significant difference was found in results among different groups. The polymerization shrinkage(v%) in group A,B, and C were (2.63 ± 0.04)%, (4.56 ± 0.06)%, and (3.98 ± 0.02)%. The elastic modulus in group A, B, and C were (9.59 ± 0.65), (4.25 ± 0.51), and (5.41 ± 0.79) GPa.
  
  
  CONCLUSIONS
  Under present study condition, using a FCR as stress-absorbing liner under composite resin restoration does not significantly decrease the polymerization shrinkage stresses at the cavity wall.
authors: Department of Dental Materials, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China. Email: zhaoxinyi@fmmu.edu.cn.
authors: Xin-yi
authors: XY
authors: Zhao
authors: Wen-yan
authors: WY
authors: Zhang
authors: Shi-bao
authors: SB
authors: Li
authors: Ya-ping
authors: YP
authors: Li
authors: Xu
authors: X
authors: Gong
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003736:Dental Cavity Lining; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D008422:Materials Testing; D058105:Polymerization
chemical_list: C084111:Charisma composite resin; D003188:Composite Resins; C111840:flowable hybrid composite