Polymerization shrinkage and depth of cure of packable composites.
OBJECTIVE
This investigation evaluated polymerization shrinkage and depth of cure of five packable composites.


METHODS
Five materials were used for the investigation: Alert, Surefil, Solitaire, P60, and Prodigy Condensable. Groups of 10 specimens of each material were made measuring either 2 or 5 mm in thickness, mounted in a testing jig, and polymerized using a dental curing light. Linear shrinkage was recorded and converted to a volumetric value. To evaluate depth of cure, ten specimens of each material were fabricated in both 2- and 5-mm thicknesses, and a Knoop hardness number was recorded on the top and bottom surfaces 5 minutes after light curing. A one-way analysis of variance statistical test was used to determine if there was a significant difference among materials. A Tukey multiple comparison test was then used to determine where significant differences existed.


RESULTS
The volumetric shrinkage for the 2-mm-thick specimens from highest shrinkage to lowest were: Solitaire (3.3%), Prodigy Condensable (1.8%), Surefil (1.4%), P60 (1.2%), and Alert (0.2%). The 5-mm-thick specimens were ranked as follows: Solitaire (2.1%), Prodigy Condensable (1.0%), P60 (0.9%), Surefil (0.8%), and Alert (0.3%). Hardness for the bottom surface of the 2-mm-thick specimens showed that P60 (48.5) and Alert (42.6) had the highest values. Solitaire (11.2) had a significantly lower value. Hardness for the bottom surface at 5-mm thickness showed Alert (16.5) and P60 (16.3) with higher values than Surefil (8.9).


CONCLUSIONS
Solitaire had the most shrinkage and Alert the least at both 2- and 5-mm depths. Depth of cure was severely compromised for all materials at 5 mm.
Herrero
Alberto A
AA
University of Michigan School of Dentistry, Department of Biologic and Materials Science, Division of Prosthodontics, Ann Arbor 48109-1078, USA.
Yaman
Peter
P
Dennison
Joseph B
JB
D003188:Composite Resins / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
C406265:Alert composite resin; D003188:Composite Resins; C443708:P60 Condensible Resin Composite; D011108:Polymers; C477351:Prodigy Condensable; C113049:Solitaire composite resin; C403464:SureFil packable composite