Effect of bulk/incremental fill on internal gap formation of bulk-fill composites.
OBJECTIVE
To examine the effects of composite type (bulk-fill/conventional) and placement (4-mm bulk/2-mm increments) on internal marginal adaptation of Class I preparations.


METHODS
Cylindrical, Class I, 4-mm×4-mm preparations were made on 50 recently extracted human molars and restored using either a bulk-fill (SureFil SDR Flow (SDR), Quixx (QX), SonicFill (SF), Tetric EvoCeram Bulk (TEC)) or a conventional composite designed for 2-mm increments (Filtek Supreme Ultra (FSU)). Restorations were placed in 1 or 2 increments using the manufacturer's bonding agent and curing light (n=5). Teeth were sectioned occluso-gingivally and dye was placed on the internal margin and visually examined by 3 observers. Gap-free marginal lengths were analysed within three different regions of the sectioned tooth: enamel, mid-dentine, and pulpal floor.


RESULTS
Marginal integrity was unaffected by placement method. Bulk-placement demonstrated significantly fewer gap-free margins at the pulpal floor than in enamel, for all materials except SDR. Greater percentages of gap-free margins were found within the mid-dentine than at the pulpal floor for FSU. QX had more gap-free margins in enamel compared with the mid-dentine. Proportion of gap-free margins within enamel and mid-dentine was not significantly different for any incrementally placed product. Excluding FSU, gap-free margins within enamel were significantly greater than at the pulpal floor. Notably, significantly more gap-free margins were found within mid-dentine than at the pulpal floor for SF.


CONCLUSIONS
No significant differences in gap-free margins were found between placement methods within a given product per location. Except for SDR, percentage of gap-free margins was significantly lower at the pulpal floor interface than at the enamel interface for bulk-fill.
Department of Oral Rehabilitation, College of Dental Medicine, United States. Electronic address: afurness@gru.edu.
Alan
A
Furness
College of Dental Medicine, United States.
Marko Yousef
MY
Tadros
Department of Biostatistics and Epidemiology, Medical College of Georgia, United States.
Stephen W
SW
Looney
Department of Oral Rehabilitation, College of Dental Medicine, United States.
Frederick A
FA
Rueggeberg
D000134:Acid Etching, Dental / Q000379:methods; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D003737:Dental Cavity Preparation / Q000145:classification*; D003743:Dental Enamel / Q000648:ultrastructure; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003782:Dental Pulp / Q000648:ultrastructure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011897:Random Allocation; D013499:Surface Properties
D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C000590992:Filtek Supreme Ultra; C553871:Surefil SDR Flow; C501891:Tetric EvoCeram
Bulk-fill; Composites; Margin adaptation