Materials&Methods: Using the Loop software program (dHal, orthodontic loop simulator 1.7.0.0) force and moment and their ratios were calculated at various positions and for various activations for a standard design of T loop (.017 × .025 TMA) given by Kuhlberg&Burstone. The values were then compared with the corresponding values determined by manual spring tester method. Statistical analysis was done using Independent t-test and multivariate regression analysis.
Results: The results showed that the alpha/beta moment ratio was dependant only on the spring position and independent of spring activation. The force system produced by a spring placed 1 mm closer to alpha attachment with 3.5 mm activation provided for bodily movement of anterior segment with M/F ratio of 9.7. This was lesser than that determined by spring tester by 0.7 for same amount of activation and same position.
Conclusion: The comparison of the two methods for designing T loop showed statistically insignificant differences in M/F values. The loop software provided for good simulation of T loop design similar to manual method. The values determined by software and manual methods were highly correlated.
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