Microleakage in class II restorations: open vs closed centripetal build-up technique.
OBJECTIVE
This study evaluated whether a Class II restoration in a flowable resin composite has to be placed prior to (open-sandwich technique) or after (closed-sandwich technique) construction of the interproximal wall in the centripetal build-up technique in order to reduce microleakage.


METHODS
Thirty non-carious molars were selected and randomly divided into two groups (n = 15). A standardized Class H preparation was made with the cervical margin 1 mm below the cementum-enamel junction. In Group 1, flowable resin composite was applied as a 1 mm base, remaining exposed at the cervical margin. In Group 2, the hybrid resin composite was applied to the interproximal wall, followed by a layer of flowable composite on the pulpal floor, away from the margins. The restorations were then subjected to 500 thermal cycles, each with a dwell time of 20 seconds at 5 degrees C and 55 degrees C. Adaptation at the cervical margin was evaluated by dye penetration and SEM analysis using the replica technique. The data were statistically analyzed using the Mann-Whitney U-test (p < 0.05).


RESULTS
The centripetal open-sandwich technique led to significantly lower dye penetration than the centripetal closed-sandwich technique (p < 0.001).


CONCLUSIONS
Flowable resin composite placed under hybrid resin composites in Group 1 provided better marginal adaptation and fewer voids. However, neither Group 1 nor Group 2 was able to completely prevent microleakage.
University of Sheffield, Adult Dental Care, School of Clinical Dentistry, Sheffield, United Kingdom. a.pollington@sheffield.ac.uk
Andrea
A
Fabianelli
Alessandro
A
Sgarra
Cecilia
C
Goracci
Amerigo
A
Cantoro
Sarah
S
Pollington
Marco
M
Ferrari
D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification / Q000379:methods; D003739:Dental Cementum / Q000473:pathology; D003743:Dental Enamel / Q000473:pathology; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003782:Dental Pulp / Q000473:pathology; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008751:Methylene Blue; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D019237:Tooth Cervix / Q000473:pathology
D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C507124:Estelite sigma; C111840:flowable hybrid composite; C086113:palfique estelite; D008751:Methylene Blue