title: Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials.
abstract: OBJECTIVE
  To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases.
  
  
  METHODS
  Twenty-four sound upper premolar teeth with Class II cavities were allocated to three groups (n=8). Restoration of the teeth involved the placement of an RBC (GrandioSO) in eight oblique increments (Group A) or Groups B and C were restored to within 2 mm of the palatal cusp in a single increment with bulk-fill flowable RBC bases (SDR and x-tra base) before the two occlusal cavity increments were placed with GrandioSO. Buccal and palatal cusp deflections were recorded postirradiation using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage.
  
  
  RESULTS
  The mean total cuspal deflection for the oblique incremental restoration technique was 11.26 (2.56) μm (Group A) and 4.63 (1.19) μm (Group B) and 4.73 (0.99) μm (Group C) for the bulk-fill flowable RBC bases. A significant increase in the mean total cuspal deflection for the incrementally filled GrandioSO compared with the SDR (P=0.007) and x-tra base (P=0.005) restored teeth was evident. No significant difference in the cervical microleakage scores was recorded between groups AC (P>0.05).
  
  
  CONCLUSIONS
  The bulk-fill flowable RBC bases significantly reduced cuspal deflection compared with a conventional RBC restored in an oblique incremental filling technique with no associated change in cervical microleakage recorded.
authors.affiliation: Materials Science Unit, Division of Oral Biosciences, Dublin Dental University Hospital, Trinity College Dublin, Ireland.
authors.forename: A
authors.initials: A
authors.lastname: Moorthy
authors.forename: C H
authors.initials: CH
authors.lastname: Hogg
authors.forename: A H
authors.initials: AH
authors.lastname: Dowling
authors.forename: B F
authors.initials: BF
authors.lastname: Grufferty
authors.forename: A R
authors.initials: AR
authors.lastname: Benetti
authors.forename: G J P
authors.initials: GJ
authors.lastname: Fleming
mesh_terms: D001641:Bicuspid / Q000502:physiology*; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental / Q000145:classification; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D012394:Rosaniline Dyes; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D019228:Tooth Crown / Q000502:physiology*
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C509998:Grandio; D008689:Methacrylates; D012394:Rosaniline Dyes; C111840:flowable hybrid composite; C100742:All-Bond 2; C025485:basic fuchsin