title: Effects of flowable composite lining and operator experience on microleakage and internal voids in class II composite restorations.
abstract: BACKGROUND
  When inexperienced clinicians perform class II composite restorations, improper placement techniques can lead to problems, including marginal adaptation and void formation.
  
  
  OBJECTIVE
  The aim of this study was to determine the influence of flowable composite linings on marginal microleakage and internal voids in class II composite restorations performed by practitioners with different levels of experience.
  
  
  METHODS
  Eighty extracted molars were prepared with mesial and distal class II cavity preparations and divided into 4 groups. Each group was restored separately with the following materials: Prodigy/Revolution lining (group I), Prodigy (group II), Tetric Ceram/Tetric Flow lining (group III), and Tetric Ceram (group IV). Each group was equally divided and restored by 2 practitioners, one experienced and another untrained in composite restorations. After restoration, all teeth were stored for 24 hours, thermocycled (at 5 degrees C to 60 degrees C) 1500 times, and soaked in 2% basic Fuchsin dye for 24 hours. After soaking, the teeth were sectioned, and gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Kruskal-Wallis test.
  
  
  RESULTS
  There was no significant reduction in microleakage for either practitioner. There were fewer interface voids within pairs with or without flowable composite linings made by the experienced practitioner (P<.05).
  
  
  CONCLUSIONS
  When flowable composite lining was placed at the gingival floor of a class II composite restoration by an experienced practitioner, voids in the restored interface were reduced. Gingival marginal sealing was not improved by the same technique.
authors.affiliation: Department of Dentistry, National Cheng Kung University Hospital, Tainan, Taiwan. lfen@mail.ncku.edu.tw
authors.forename: S F
authors.initials: SF
authors.lastname: Chuang
authors.forename: J K
authors.initials: JK
authors.lastname: Liu
authors.forename: C C
authors.initials: CC
authors.lastname: Chao
authors.forename: F P
authors.initials: FP
authors.lastname: Liao
authors.forename: Y H
authors.initials: YH
authors.lastname: Chen
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003736:Dental Cavity Lining; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D012394:Rosaniline Dyes; D013499:Surface Properties; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C099128:Prodigy; C102735:Revolution (composite resin); D012394:Rosaniline Dyes; C090969:Tetric; C121818:Tetric ceram; C111840:flowable hybrid composite