Slumping during sculpturing of composite materials.
OBJECTIVE
This study investigated the slumping characteristics of four composite materials during sculpturing prior to their polymerization.


METHODS
Four different composite materials were used to measure shape deformation due to slumping. Silicon impressions of the occlusal plane of three different molars were used as a mould for the composite samples. The surface of the samples was digitized with a laser scanner (400 slices, lateral resolution: 25 microm). Scans were made after 1-4 min. The 3D data sets were numerically superimposed with matching software and differences were calculated relative to the baseline measurement.


RESULTS
The amount of surface deformation increases with increasing observation time. The average coefficient of variation was 0.2. The largest mean amount of slumping was observed for ELS with tooth mould 1 (150.0 microm), and for Clearfil Majesty with tooth mould 2 (98.3 microm) and mould 3 (42.8 microm). Miris 2 Dentin and Synergy D6 Enamel were rather similar and seem to exhibit little deformation. The slump flow of ELS and Clearfil Majesty was up to 400% higher than the formers. The deformation could be sorted in the following order "mould 3"<"mould 2"<"mould 1" for all materials and all observation time. There was a significant influence (p<0.05) of the three factors, time, mould and composite type (ANOVA).


CONCLUSIONS
This specific method provides a reproducible approach for the assessment of the handling characteristics of composite materials. The results can identify slumping differences and assist in collecting information about the feasibility of a material for certain indications.
Chiang
Yu-Chih
YC
School of Dentistry and Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan.
Knezevic
Alena
A
Kunzelmann
Karl-Heinz
KH
D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D008422:Materials Testing; D008963:Molar; D053761:Nanocomposites; D010316:Particle Size; D012212:Rheology; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
D003188:Composite Resins