Impact of botulinum toxin type A on tooth movement and bone remodeling in male Wistar rats

We evaluated whether the use of botulinum neurotoxin type A (BTX-A) in masticatory muscles influences tooth movement and bone remodeling.

Seventy-seven male Wistar rats were allocated to the groups: S - Saline (n=20); SM - Saline with movement (n=20); BT - Botulinum toxin (n=18); BTM - Botulinum toxin with movement (n=19). On day 1, 0.02 mL of sterile 0.9 % saline was administered to groups S and SM and BTX-A (1 U in 0.02 mL of saline) to groups BT and BTM, in the masseter and temporal muscles laterally. On day 30, a nickel titanium spring was installed to move the first maxillary molar and euthanasia was performed on days 32 and 51. Tooth displacement, maxillary and mandibular bone volumes, collagen neoformation, bone and root resorptions, and masseter morphometry were assessed. Statistical analysis was conducted (p < 0.05).

A higher percentage of type I collagen was observed in the BT than in the S group on day 51 and lower mass, length, and diameter of the masseter fibers in BT and BTM (p < 0.05). Tooth displacement, bone volume, bone and root resorptions, hyaline area, and masseter height showed no difference among groups with and without BTX-A, regardless of tooth movement (p > 0.05).

BTX-A did not interfere with tooth displacement, bone volume, and dental and periodontal tissues related to tooth movement in rats; it increased mature collagen in animals without tooth movement; and it caused a decrease in the mass, length, and diameter of the masseter fibers.