title: Bulk fill restoratives: to cap or not to cap--that is the question?
abstract: OBJECTIVE
  To assess the cuspal deflection and cervical microleakage scores of standardised large mesio-occlusal-distal (MOD) cavities filled with different restoration protocols: (1) conventional resin restoratives, (2) bulk fill flowable base materials 'capped' with a conventional dimethacrylate resin-based composite (RBC) or (3) bulk fill resin restorative materials.
  
  
  METHODS
  Standardised MOD cavities were prepared in sixty-four sound maxillary premolar teeth and randomly allocated to eight groups. Restorations were placed in conjunction with a universal bonding system and resin restorative materials were irradiated with a quartz-tungsten-halogen light-curing-unit. Restoration protocol (eight oblique increments of conventional resin restorative, bulk fill flowable base and two occlusal 'capping' RBC increments (three increments in total) or bulk fill resin restorative (two increments)) was the dependent variable. A twin channel deflection measuring gauge measured the buccal and palatal cuspal deflections. Teeth were thermally fatigued, immersed in a 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage score.
  
  
  RESULTS
  Post hoc Tukey's tests highlighted significant differences in the mean total cuspal deflection values between resin restoratives (p < 0.0001) and restoration protocol (p < 0.005). In general (albeit product dependently), an increase in mean total cuspal deflection and concomitant decrease in cervical microleakage score was evident for bulk fill flowable base materials with occlusal 'capping' RBC increments (restoration protocol 2) compared with bulk fill resin restoratives (restoration protocol 3).
  
  
  CONCLUSIONS
  Not all bulk fill flowable materials or bulk fill resin restoratives behave in a similar fashion when used to restore standardised MOD cavities in maxillary premolar teeth and material selection is vital in the absence of clinical data.
  
  
  CONCLUSIONS
  Poorly performing bulk fill flowable materials or bulk fill restoratives can be identified using the cuspal deflection and cervical microleakage protocol which could save the complications encountered clinically when restoring Class II restorations.
authors.affiliation: Department of Medical Education, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Iwona M
authors.initials: IM
authors.lastname: Tomaszewska
authors.affiliation: Materials Science Unit, Dublin Dental University Hospital, School of Dental Science Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Jennifer O
authors.initials: JO
authors.lastname: Kearns
authors.affiliation: Department of Restorative Dentistry, Dental School of the Ludwig Maximilians University, Goethestr 70, Munich 80336, Germany.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Ilie
authors.affiliation: Materials Science Unit, Dublin Dental University Hospital, School of Dental Science Trinity College Dublin, Dublin 2, Ireland. Electronic address: garry.fleming@dental.tcd.ie.
authors.forename: Garry J P
authors.initials: GJ
authors.lastname: Fleming
mesh_terms: D003188:Composite Resins / Q000627:therapeutic use; D003763:Dental Leakage; D003793:Dental Restoration, Permanent / Q000379:methods; D006801:Humans; D019228:Tooth Crown
chemical_list: D003188:Composite Resins
keywords: Bulk fill flowable base materials; Bulk fill resin restorative; Cervical microleakage score; Cuspal deflection measurement; Resin-based composite; Restoration protocol