Biomechanical analysis of anchorage reinforcement by intrusion arch

Abstract

Objective To determine the suitable anchorage bend in intrusion arch for anchorage reinforcement while retracting canines.Methods According to Burstone segmental arch wire technique,intrusion arch were fabricated by 0.017” × 0.025” beta titanium alloy( TMA),and working arch wire were fabricated by 0.016” × 0.016” stainless steel archwire,meanwhile canines were retracted distally by spring coil with 150 g force.OMSS were used to imitate the situation in clinic.Force and moments were measured three dimensionally at incisor segment,canine segment and posterior segment with 20,30,40 degree bite-opening bend in the intrusion arch separately.Results OMSS test showed that molar segment tipped mesially by 10 degree without intrusion arch,and molar segment tipped mesially by 5 degree while canine retracted distally when intrusion arch were activated by 20 degree tip back,and molar segment tipped distally by 5 degree while canine retracted and translated distally and with the aid of intrusion arch activated by 30 degree tip back,molar segment tipped distally by more than 10 degree while canine retracted and tipped distally with the aid of intrusion arch activated by 40 degree tip back.Conclusions Intrusion arch activated by 30 degree is preferred for the best anchorage reinforcement while canine retracted distally. Key words: Intrusion arch; Anchorage bend