Objectives. Handling characteristics and application modes of resin co
mposites are important factors to achieve proper placement of the rest
orative materials. The present study was undertaken to assess the infl
uence of the consistency of composite materials and the mode of applic
ation on voids and porosities in Class I adhesive restorations. Method
s. One hundred medium-sized Class I preparations with an adhesive desi
gn were restored with three composites of various consistencies using
three different application modes. The restorations were sectioned, an
d each section of a restoration was inspected for the presence of void
s. The total surface and the percentage of the cavity wall occupied by
voids as well as the total number of voids in the sections were recor
ded. A Krusal-Wallis analysis of variance was carried out on the data.
Differences between individual composite materials for each mode of a
pplication and between individual application modes for each composite
material were analyzed using a Mann-Whiiney U-test at p < 0.05. Resul
ts. The injection technique with a Hawe Neos Centrix tip was the best
mode of application. Both smearing and the condensation of composites
appeared to produce unreliable results. Furthermore, there were more p
roblems with voids and wall adaptation for the thicker-consistency com
posite than for the medium- and thin-consistency material. Significanc
e. The thick-consistency composite had more problems related to voids
and wall adaptation than the medium- and thin-consistency composites.