AU - Khanna, Bharat AU - Sharma, Vineet TI - An in vitro evaluation of biomechanical characteristics of the “pendulum” appliance PT - ORIG DP - 2015 Jan 1 TA - Journal of Integrative Nephrology and Andrology PG - 29-34 VI - 2 IP - 1 4099- http://www.journal-ina.com/article.asp?issn=2394-2916;year=2015;volume=2;issue=1;spage=29;epage=34;aulast=Khan;type=0 4100- http://www.journal-ina.com/article.asp?issn=2394-2916;year=2015;volume=2;issue=1;spage=29;epage=34;aulast=Khan AB - Objective: The objective of the study was to determine the optimum preactivation angle of the pendulum spring depending on the force required for molar distalization and to develop a patient recall protocol depending on the amount of force decay in the pendulum spring. Materials and Methods: A test jig was fabricated using 5 mm thick plexiglass sheets representing the maxillary arch. Forty identical pendulum springs were fabricated according to the specifications by Hilgers. The springs were divided into four groups according to the preactivation angle of the active arm of springs from the line perpendicular to the midpalatal line. Force exerted by the pendulum spring was measured with the help of the spring tester at 0, 30, 60, and 90 days. Results: There was significant force decay in different angle groups with time except in 45° and 60° angle group from 60 to 90 days. Conclusion: Force delivered by the pendulum spring with 45° preactivation angle is optimum for maxillary molar distalization if the design of the spring given by Hilgers is adhered to. The force exerted by the spring with 45° preactivation angle remains optimum for maxillary molar distalization till 60 days.