Comparison of Rate of En masse Retraction and Anchorage Loss in Conventional Labial Appliance with Labial and Lingual Force: A Clinical Study

Abstract

The rate of en masse retraction and anchorage loss were compared between labial appliance with lingual force and conventional labial appliance. Subjects and Methods: The sample consists of 14 patients and they were divided into two groups. In Group 1 -labial appliance with lingual force, elastomeric chain was placed from the palatal surface of the canines to the palatal surface of the molars. In Group 2 -labial appliance with labial force, elastomeric chain was placed from the crimpable hook distal to lateral incisor to the molar tube hooks. The rate of en masse retraction and anchorage loss was calculated for both the groups during retraction in dental casts (R 0 , initial; R 1 , 4 weeks; R 2 , 8 weeks; and R 3 , 12 weeks). Statistical Analysis Used: Student's paired t-test. Results: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, i.e., Group 1. The difference of anchorage loss in Group 1 and Group 2 shows t = 4.824 and P value= 0.000, which is statistically highly signifi cant. The difference of rate of retraction in Group 1 and Group 2 shows t = 3.573 and P value = 0.004, which is statistically signifcant. Conclusions: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, thus indicating that this new technique of space closure utilizes biomechanical advantage of lingual force in conventional labial appliance.

Evaluation of the Rate of En-masse Retraction in Orthodontic Patients with Maxillary Protrusion Using Friction versus Frictionless Mechanics: A Randomized Clinical Trial

“…Sample size calculation was done using the comparison of rate of space closure between labial force method and T-loop spring method. As reported in previous publication 17,18 . The mean ± SD of rate of space closure in labial force method group was approximately 0.88 ± 0.05 mm, while in T-loop spring method group it was approximately 0.708 ± 0.157 mm.…”

Maxillary canine retraction rate using two different orthodontic mechanics (A prospective clinical study)

“…(17) In lingual orthodontics, the point of force application is on the lingual side and this difference in the aspect of point of force application and its varying distances from the center of resistance in both sagittal and vertical planes, are the key reasons why teeth respond differently to lingual technique (11,18) . Quraishi et al, (14) compared between labial appliance with lingual force and conventional labial appliance. The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, thus indicating that this new technique In the present study, the canine retraction rate was measured clinically using dental vernier at monthly intervals.…”

“…As a consequence, torque is more difficult to control in lingual orthodontics (4,9,11,12) . This limitation of torque control during retraction in lingual orthodontics has been overcome by the use of labial appliance with lingual force instead of lingual appliance with lingual force (6,14) . Takemoto (6,8) compared the anchorage loss in bimaxillary protrusion subjects treated with labial and lingual appliances and concluded that a minimal amount of 0.1-0.5 mm of anchorage loss was observed with retraction of up to 7.9 mm with lingual appliances (6,8,13) .…”