Bimaxillary protrusion is a condition characterized by proclined upper and lower incisors with an increased prominence of the lips. This is a case of a 18-year-old with bimaxillary protrusion, mild crowding on the maxilla and mandible, and mandibular dental midline shift to the left by 1 mm. The four first premolars were extracted using a pre-adjusted bracket. This bracket had in-built prescriptions of torque, tip, and in-out for orthodontic cases. There were three pre-adjusted orthodontic bracket systems: Andrews, Roth, and MBT. T-loop was also used to achieve controlled space closure. After 26 months of orthodontic treatment, the patient’s profile was straighter and a pleasant smile was achieved at the end of treatment.

Background: Orthodontic tooth movement occurs due to bone resorption and apposition on the pressure and tension side of the PDL. The transcription factors associated with osteoclast differentiation are NFATc1 while osteoblast differentiation is associated with RUNX2. The optimum force of orthodontic tooth movement can move the teeth to the desired position, without causing discomfort and tissue damage to the patient. Objective: This study aims to analyse the effect of gradually increasing force on orthodontic tooth movement (by evaluating the NFATc1 and RUNX2 expression) in rats. Methods: This research is an in vivo experimental study with a post-test control group design. Twenty-eight healthy male adult Wistar rats (Rattus novergicus) aged 4-5 months with body weights 200-250 g rats were divided into seven study groups. Treatment groups in this study are given the force (by applying a closed coil spring between the maxillary central incisor and the maxillary first molar) of 5 g, 5-10 g, 10 g, and 10-20 g with the duration of treatment in 14 and 28 days. After the treatment day was finished, the alveolar bone tissue was isolated and investigated by immunohistochemical methods. Results: Indicate a significant difference between the control and all treatment groups of NFATc1 (p=0.003; p=0.000; p:0.010; p=0.001; p=0.001; p=0.000) and RUNX2 with groups of 10 g/14 days, 10 g/28 days, 5 g/28 days, 10 g/14 days,10-20 g/28 days (p=0.001; p=0.000; p=0.000; p=0.017; p=0.014; p=0.000) values. Conclusion Gradually increasing force affects orthodontic tooth movement by inducing bone resorption (high expression of NFATc1) in the pressure area and bone apposition (high expression of RUNX2) in the tension area. Applying heavy force by initially applying light force could inhibit hyalinization.
Orthodontic Tooth Movement ; Tooth Movement Techniques