Emotional stress- and pain-related behaviors evoked by experimental tooth movement

• Published in: The Angle orthodontist Vol. 78; no. 3; pp. 487 - 494
• Main Authors: Yozgatian, Joseph H, Zeredo, Jorge L, Hotokezaka, Hitoshi, Koga, Yoshiyuki, Toda, Kazuo, Yoshida, Noriaki
• Format: Journal Article
• Language: English
• Published: United States 01-05-2008
• Subjects: Animals; Behavior, Animal - physiology; Dental Alloys; Dentistry; Escape Reaction - physiology; Exploratory Behavior - physiology; Grooming - physiology; Locomotion - physiology; Male; Nickel; Orthodontic Appliance Design; Orthodontic Wires; Pain - physiopathology; Pain - psychology; Rats; Rats, Sprague-Dawley; Stress, Mechanical; Stress, Psychological - physiopathology; Stress, Psychological - psychology; Time Factors; Titanium; Tooth Movement Techniques - instrumentation; Tooth Movement Techniques - psychology
• ISSN: 0003-3219; 1945-7103
• DOI: 10.2319/040207-165.1

To investigate by behavioral methods the relationship between emotional stress and pain during experimental tooth movement in rats.
Sixteen male Sprague-Dawley rats (210 to 250 g) were divided into two groups. The experimental group was treated with an active Ti-Ni appliance, and the control group received a passive appliance. A force of 20 gf was delivered by the active appliance between the maxillary first and second molars for 3 days. During this period the rat's behavior was evaluated eight times by means of open-field test and resistance-to-capture test. The specific parameters of animal activity were facial grooming, rearing, and locomotor activity, movement into the center of the open field, and response to capture.
Parameters related to stress and pain were higher in the group carrying active appliance, compared to the group with a passive appliance. Statistically significant differences in stress-related behavior between control and experimental groups were found 8 hours after placing the appliance and were most evident on the second day. Pain-related behavior was significantly greater in the experimental group than in the control group at 24 hours.
The increase in emotional stress evoked by orthodontic tooth movement may precede the appearance of periodontal pain.