Effect of resin-composite filler particle size and shape on shrinkage-strain.
OBJECTIVE
The aim of this study was to investigate the effect of variations in filler particle size and shape on the polymerization shrinkage-strain kinetics of resin-composites.


METHODS
A model series of 12 VLC resin-composites were studied. The particulate dispersed phase volume fraction was 56.7%: these filler particles were systematically graded in size, and further were either spherical or irregular. The bonded disk method was used to determine shrinkage-strain kinetics. Displacement was recorded following 40s irradiation (600mW/cm(2)) at 23 degrees C (n=3). All data were captured for 60min and the final shrinkage-strain calculated.


RESULTS
For materials with spherical filler, shrinkage-strain was 2.66% (SD 0.18) for those with irregular filler it was 2.89% (SD 0.11). These differences were statistically significant (p<0.001): the Scheffé test identified two subsets, those with irregular filler (including materials with a multimodal mix) and those with spherical filler (including materials with a multimodal mix). Additionally, there was a trend for higher shrinkage-strain values with decreasing filler particle size which was apparent for both those composites with spherical filler particles and those with irregular filler particles. For irregular filler particles, linear regression gave a high correlation (r(2)=0.99).


CONCLUSIONS
Statistically significant differences were identified in the shrinkage behavior of resin-composites with differing filler size and shape.
School of Dentistry, University of Manchester, Higher Cambridge Street, Manchester M15 6FH, UK. julian.satterthwaite@manchester.ac.uk
Julian D
JD
Satterthwaite
Karin
K
Vogel
David C
DC
Watts
D017609:Barium Compounds / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D005459:Fluorides / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry / Q000528:radiation effects; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry / Q000528:radiation effects; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000528:radiation effects; D011140:Polyurethanes / Q000737:chemistry / Q000528:radiation effects; D011829:Radiation Dosage; D012821:Silanes / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013729:Terpenes / Q000737:chemistry / Q000528:radiation effects; D013997:Time Factors; D015018:Ytterbium / Q000737:chemistry
D017609:Barium Compounds; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; D011140:Polyurethanes; D012821:Silanes; D017640:Silicates; D013729:Terpenes; C121818:Tetric ceram; C415406:barium borosilicate; C102738:barium glass filler; C029824:urethane dimethacrylate luting resin; C102799:ytterbium fluoride; C020946:triethylene glycol dimethacrylate; C017492:methacryloxypropyltrimethoxysilane; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C048339:camphoroquinone; D012822:Silicon Dioxide; D015018:Ytterbium; D005459:Fluorides