Orthodontic patients have reported the use of analgesics during therap
y. However, common anti-inflammatory analgesics, such as aspirin and i
buprofen, have been shown to slow the rate of tooth movement. Acetamin
ophen, another common analgesic, does not possess anti-inflammatory pr
operties. The effect of acetaminophen on tooth movement was studied us
ing New Zealand white rabbits. Experimental animals were matched to a
control animal of the same sex and weight. Under anesthesia, springs w
ere ligated between the lower first molar and incisor, resulting in ap
proximation of these teeth. Under blinded conditions, seven of the rab
bits received 1000 mgs of acetaminophen daily. Seven control animals r
eceived water. The animals were sacrificed after 21 days. The movement
of incisors and molars was measured. Results showed considerable move
ment within both the experimental and control groups, but no significa
nt difference in tooth movement between them. Acetaminophen has no eff
ect on the rate of tooth movement in rabbits undergoing orthodontic tr
eatment.