A comparative evaluation of different compensating curves in the lingual and labial techniques using 3D FEM 

Sang Jin Sung, Hyoung Seon Baik, Yoon Shik Moon, Hyung Seog Yu,
Young Soo Cho, Am J Orthod Dentop 2003;123;441-450

Review: Rafi Romano D.M.D., M.Sc

www.lingualnews.com, Vol1, No 3 - July 2003

Only few studies compare tooth movement of the lingual technique with that of the labial technique. In this study, human mandibular left teeth were aligned, and a 3- dimensional finite element model was made (consisting of 19382 nodes and 12150 elements). To compare the effect of compensating curves on canine retraction between the lingual and the labial orthodontic techniques, the compensating curve was increased on the .016-in stainless steel labial or lingual archwire, and a 150-g force was applied distally on the canine. The relative direction and the amount of tooth displacement of the finite element model were compared on a schematic displacement graph (magnified 10,000 times), and the compressive stress distributed on the root surface was observed. The pattern of tooth movement (with or without a compensating curve) was different between the labial and the lingual techniques. As the amount of compensating curve increased (0, 2, and 4 mm) in the archwire, the rotation and the distal tipping of the canine was reduced. The antitip and antirotation action of compensating curve on the canine retraction was greater in the labial archwire than in the lingual archwire

Conclusion:
1. As the amount of compensating curves (CC) increased (0, 2, 4 mm) in the archwire, the rotation and the distal tipping of the canine were reduced.
2. When the canine was retracted on a .016-in SS archwire with a 4-mm CC, the compressive stress on the distal root surface of the canine was reduced and distributed evenly to the level of the apical half with the labial technique, and the tensile stress affecting the apical area disappeared.
3. The antitip and antirotation action of the CC on the canine retraction was greater in the labial archwire than in the lingual archwire.

www.lingualnews.com 
Adult and Lingual Orthodontics
EDITORS:
Dr. Silvia Geron D.M.D., M.Sc
Dr. Rafi Romano D.M.D., M.Sc
Dr. Pablo Echarri D.M.D., M.Sc