Stress distribution analysis in anterior teeth caused by several retraction mechanics

Abstract

Introduction: Orthodontic retraction of the anterior teeth is indicated when the patient has a malocclusion with protrusion of the incisors. Several mechanics are indicated to perform this retraction. Objective: The objective of this study was to compare the strains generated by four different types of retraction mechanics along the roots of the anterior teeth. Methods: A photoelastic model simulating an arch with first premolars extraction was made. Sixty retraction archwires were prepared, including fifteen for each type of mechanics evaluated: sliding, teardrop loop spring, T-loop spring and double key loop archwire. The strains were observed in two perspectives: occlusal and oblique. In the occlusal perspective, strains were compared among the six anterior teeth. From the oblique perspective, strains were compared among the thirds of the left canine root. Results: In the occlusal perspective, the teardrop loop spring mechanics presented greater strains, followed by T-loop spring, double key loop archwire and sliding mechanics. In all mechanics, strains were more concentrated in the canines than in the incisors. From the oblique perspective, the teardrop loop mechanics generated greater strains in the cervical regions of the canine, and in the apical regions, no differences were found in strains among the four types of mechanics. In the same mechanics, greater strains were present in the cervical zones. Conclusion: The teardrop loop spring retraction mechanic presented the greatest mean strain, and the sliding retraction mechanic presented the lowest mean strain on the root of anteroinferior teeth in the occlusal and oblique perspectives.

A Comparative evaluation of stress distribution in bone and mini-implant during en-masse retraction of anterior teeth in maxilla using forces from anchorage units (mini-implants and molar hook) to both canine hook and arch wire hook. An FEM study

“…From the above-mentioned study, we can say that Figure 1 where retraction was carried out from mini-implant to the arch wire hook can help in achieving bodily tooth movement without the loss of anchorage, can be achieved. Domingos et al 14 found that stress was concentrated on the canine region. Lee et al 15 in their study stated that an absolute anchorage tends to decrease the stress on the posterior aspect of the teeth and concentrates on the roots of the anterior teeth as well.…”

Recent Advances in Orthodontic Archwires: A Review

“…Added advantages of this type of archwires are that it prevents the undesirable tilting of the molars and rotation of the premolars and it has a mild impact on the anterior teeth that will not cause pain to patients. Aside from that, the 3D control over these wires is available since the start of treatment [27][28][29][30].…”