A new orthodontic force delivery system for beagle dogs

A large number of experimental studies in a variety of animal species have been performed to obtain insight into the biological response to orthodontic forces. New developments in orthodontic mechanics and surgical adjuncts merit further investigations in animal model. Beagle dog is a well-established model for orthodontic research. Beagle's root cementum, periodontal ligament and alveolar bone structure and physiology closely resemble those of human. Objectives: A novel design of orthodontic appliance to achieve reliable translational bodily tooth movement with constant force for future clinical studies is tested in beagle dogs. Methods: Five beagle dogs, aged 24 to 36 months, were used in this study. All third premolars were extracted; fourth premolars were used as anchors and second premolars were moved by newly designed appliance distally towards the extracted third premolar positions. Mini-screws placed apical to buccal furcations of first molars were used to stabilize anchoring teeth and as landmarks for radiography. 1.2 N of orthodontic force was equalized with NI-TI spring coil in every appliance. Apical and coronal measurements of tooth movement were recorded weekly by measuring the distance between 2 separate indentations on the canine and second premolars with digital caliper with precision to 0.01 mm; tooth movement was followed for 8 weeks. Result: 0.05-0.4 mm of bodily movement was achieved weekly and confirmed by peri-apical X-ray monthly. No gross tipping or rotation was observed. All appliances remained intact until the end of the study. Conclusion: The design of experimental appliance permits reliable induction and maintenance of bodily tooth movement in beagle dogs with controlled amount of force and can be used in the future experiments for evaluation of various aspects of orthodontic tooth movement. (Bernard J. Schneider Fund and Edward C. Wach Fund)