Methods: We used Brown-Norway (BN) rats, which are known as high IgE producers after sensitization that develop late airway response after antigen challenges. Six-week-old male BN rats were actively sensitized by ovalbumin. Seven days after the sensitization, a stretched closed-coil spring as an orthodontic appliance was placed between the maxillary right first molar and the incisors moving the molar mesially with a force of 10g. After 7 or 14 days of tooth movement, the animals were fixed and sacrificed. The molars with alveolar bone were dissected and processed for tartrate-resistant acid phospatase (TRAP) histochemistry. The levels of inflammatory cytokines were measured by enzyme linked immunoassay (ELISA). The control group was also applied with the coil spring without antigen challenge. The effect of peroral administration of aspirin was also investigated.
Results: The root resorption lacuna in the pressure zone was wide and deep. The number of odontoclasts and osteoclasts was significantly elevated in the sensitized group compared with that of the control group. The expression levels of TNF-α, IL-1β and IL-6 were increased in the sensitized group. Aspirin administration diminished the resorption area, the number of osteoclasts and odontoclasts and the level of inflammatory cytokines.
Conclusion: Our results suggest that a systemic allergy is one of the risk factors for orthodontic root resorption and aspirin administration could be a new therapeutic approach.