Effect of celecoxib on emotional stress and pain-related behaviors evoked by experimental tooth movement in the rat.

OBJECTIVE: To test the efficacy of an animal model of pain and stress and evaluate the effects of celecoxib administered when orthodontic force is applied. MATERIALS AND METHODS: A 20-g reciprocal force was applied via an orthodontic appliance to the maxillary left first and second molars of 7-week-old male Sprague-Dawley rats. Rat behavior was evaluated at 5, 24, and 48 hours after the appliance was set. Behavior was assessed in a test field by the number of lines crossed in the first 30 seconds and 5 minutes following force application; number of lines crossed to the center; rearing time; and facial grooming time. Experimental group 1 received intraperitoneal administration of 30 mg/kg celecoxib before every behavioral test. Experimental group 2 received 90 mg/kg before the first behavioral test, and physiologic saline was administered before the remaining behavioral tests. Control groups received saline before every behavioral test and were given passive (passive control group) and active (active control group) appliances, respectively. RESULTS: Parameters related to pain increased in the active controls, whereas the parameters in the experimental groups decreased to the level seen in the passive controls. Statistically significant differences in pain-related behavior between control and experimental groups were found at 5 and 24 hours after placing the appliance. Stress-related behavior was significantly less in the experimental groups compared to the active control group during experimental periods. CONCLUSIONS: The administration of celecoxib relieves pain- and stress-related behavior evoked by orthodontic tooth movement in the rat. This model might be a useful tool for the evaluation of pain and stress.

Effects of steroidal and nonsteroidal drugs on tooth movement and root resorption in the rat molar.

OBJECTIVE: To test the hypothesis that the administration of aspirin, acetaminophen, meloxicam, celecoxib, and prednisolone have no effect on root resorption and tooth movement. MATERIALS AND METHODS: A mesial force of 50 g was applied to the left maxillary first molars of sixty 10-week-old male Wistar rats using nickel titanium closed coil springs attached to the cervical area of the incisors. The rats were randomly divided into 12 groups of 5 each. High and low doses of aspirin, acetaminophen, meloxicam, celecoxib, and prednisolone were administered via drinking water for 2 weeks. The experimental control group had tooth movement but received no drug. The negative control group received neither tooth movement nor drugs. The amount of tooth movement was measured on digitized lateral cephalometric radiographs. Rats were sacrificed after 2 weeks. Mesial and distal roots (distobuccal and distopalatal) were examined using scanning electron and three-dimensional (3D) scanning laser microscopes. The surface area, depth, volume, and roughness of the root resorption craters were measured. RESULTS: When compared with experimental control rats, only prednisolone- and high-dose celecoxib-treated groups showed significantly less root resorption and less tooth movement. Although low dose celecoxib-treated group significantly decreased the tooth movement, root resorption was similar to the control group. Furthermore, resorption craters showed a smoother surface in the prednisolone-treated rats. CONCLUSIONS: The hypothesis was rejected. Administration of prednisolone and high-dose celecoxib reduces root resorption and interferes with tooth movement in rats. Both drugs may interfere in the arachidonic acid cascade depending on dose thresholds.

Experimental determination of optimal force system required for control of anterior tooth movement in sliding mechanics.

INTRODUCTION: This study was designed to determine the optimum vertical height of the retraction force on the power arm that is required for efficient anterior tooth retraction during space closure with sliding mechanics. METHODS: Three adults (1 man, 2 women) with Angle Class II Division 1 malocclusions were selected for this study. In each subject, the maxillary right central incisor was the target tooth. Initial tooth displacements of that tooth with sliding mechanics with various heights of retraction forces were measured in vivo by a 2-point 3-dimensional displacement magnetic sensor device. The tooth's motion trajectories on the midsagittal plane were studied. RESULTS: The location of the center of rotation of the target tooth varied according to the different heights of the retraction forces. Controlled anterior tooth movement (ie, lingual-crown tipping, lingual-root movement) can be predicted, simulated, or even manipulated by different heights of retraction forces on the power arm in the sliding mechanics force system. A power arm length of 3 to 5 mm is estimated to produce controlled lingual-crown tipping (with the apex as the center of rotation) for efficient anterior tooth retraction during sliding space closure in adults with Angle Class II Division 1 malocclusion. CONCLUSIONS: Knowing and applying the correct height of retraction force on the power arm is the key to efficient anterior tooth retraction.