This research investigated the effects of vibration on the rheological properties of dental composites and the adaptation of tooth cavity-composite interfaces. A portable vibratory packing device and two composites, micro-hybrid dental composite (MC) and nano-hybrid dental composite (NC), were evaluated. The frequency and amplitude of the vibratory packing device were measured. Dynamic oscillatory shear tests were conducted with varying frequency to examine the rheological properties of the composites. Twenty identical composite teeth with a Class I cavity were prepared and filled with one of the two composites. The composite was placed into a cavity using the vibratory packing device operating in either ON or OFF mode. After light-curing of the composite, the gap between the tooth and the composite was evaluated using micro-computed tomography. Two-way ANOVA was used to evaluate the effects of vibration and composite type on tooth-composite adaptation. The frequency of the vibratory packing device was 66.8 Hz. The complex viscosity, η*, of NC was higher than that of MC, and η* of both composites significantly decreased with increasing oscillation frequency. However, the application of vibration did not enhance adaptation at the tooth-composite interface.