الفهرس 
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Abstract
This is a case control study on 20 animal models aiming to evaluate the effects of orally ingested Atorvastatin on relapse of teeth after 3 weeks of applying 150cN of orthodontic force on the 1st premolar in 16-week-old healthy male white New Zealand rabbits weighing between 2.1 and 2.6 kg at the start of the work with normally developed dentition.
Animals were anesthetized using intramuscular injection of xylazine and ketamine, a closed coil Ni-Ti spring was inserted between the lower incisors and the lower 1st premolar, 150cN of force was measured before using ligature wire and resin cement to hold the appliance in place, the appliance was left for 3 weeks to attain the desired tooth movement, animals were kept in housing with fresh air, day and night cycles and fed a soft diet to prevent appliance breakage during the orthodontic movement period. After 3 weeks of orthodontic tooth movement the animals were anesthetized and the appliance was removed, records were taken using rubber base impression materials immediately after. Animals were split randomly into 2 groups; study group was fed 20mg/kg of Atorvastatin Calcium powder suspended in distilled water orally via gavage daily for 21 days. Control group were force fed an equal amount of phosphate-buffered saline solution via gavage also. After 21 days another record was taken using rubber base impression material and 1 animal was randomly selected from both groups for histological analysis.
Impressions were previously poured into casts with extra hard stone, models were transformed into. stl form using a 3D scanner creating 3D models for measuring the distance between the 1st and 2nd premolar at both stages of the study using View box software. Animals chosen for histological analysis had their mandibles dissected, then sliced in half, fixed, and decalcified. Nine randomly chosen sections per specimen were processed from parasagittal serial sections of 6-mm thickness. Hematoxylin and eosin was used to stain the sections. Under a light microscope, sections of the interdental space between the mandibular first and second premolars were photographed. Osteoclastic count, osteoblastic count, cortical thickness, number of bone trabeculae, bone density (intensity), and number of blood vessels were among the histomorphometric characteristics assessed.
Mean distance between 1st premolar and 2nd premolar in animals before and after relapse were calculated, also the percentage of relapse was noted, both values were compared in both control and study groups, there was a significant decrease in relapse percentage in study groups compared to control groups. Also, histological analysis showed significant difference in a number of parameters such as bone area, bone trabeculae and osteoclast cells count.
Our results show potential positive effect of atorvastatin on decreasing the percentage of relapse after orthodontic tooth movement in animal model, both in the relapse percentage and some of the histomorphometric parameters related to bone remodeling.