How should composite be layered to reduce shrinkage stress: Incremental or bulk filling?

Objectives. The purpose of this study was to determine the effect of different layering techniques on cuspal deflection in direct composite restorations. Methods. Aluminum blocks were used to prepare MOD cavities divided into three groups. Each cavity was restored with composite using three different filling techniques. Group 1 was filled in bulk, group 2 was restored by a horizontal increment technique, and group 3 by an oblique increment technique. Cuspal deflection was measured with LVDT probes and compared among groups using ANOVA and Scheffe's post hoc test (alpha = 0.05). Results. The cuspal deflections in groups 1-3 were 21.6 +/- 0.90 mu m, 19.3 +/- 0.73 mu m and 18.4 +/- 0.63 mu m, respectively. The bulk filling technique yielded significantly more cuspal deflection than the incremental filling techniques, while there was no significant difference between the horizontal and oblique increment methods. Significance. Cuspal deflection resulting from polymerization shrinkage can be reduced by incremental filling techniques to obtain optimal outcomes in clinical situations. (C) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.