The objective of this study was to measure the linear polymerisation shrinkage of a range of composite resin restorative materials, of varying particle type, using a dilatometer modified from the design of Watts and Cash (1991).
Methods:
The materials used were; Filtek Supreme, Z250, Z100 (3M ESPE), Venus (Heraeus-Kulzer), Vitalescence (Ultradent), Nulite F (NSI), and Grandio (VOCO). Approximately 135mm3 of composite was positioned on a glass slide, covered with a cover slip, and compressed to approximately 1.5mm thickness. The resin was cured in the apparatus for 180 seconds using an ESPE Elipar II curing light while the shrinkage was continuously recorded. Final thickness was measured (Mitutoyo Digimatic Indicator -resolution 1 micron),the measured change was added and percent change calculated.
Results: Mean percent shrinkages at 40 and 120 seconds were; Filtec Supreme (FS) 1.19 and 1.68; Z250 1.63 and 1.75; Z100 2.01 and 2.20; Grandio (G) 1.6 and 1.54; Nulite F (NF) 1.95 and 2.35; Venus (VE) 2.40 and 2.69 and Vitalesce (VI) 2.93 and 3.3. Statistically (p > 0.05) at 120 seconds, FS, Z250 and G were not statistically different but did differ from NF, Z100, VE and VI. VI differed from all others. No difference existed between NF, Z100 andVE.
Conclusions: The use of the laser-triangulation sensor allows continuous monitoring, is non-contact, simple to use and clearly differentiates comparative polymerization shrinkage.