Optimization of configuration of attachment in tooth translation with transparent tooth correction by appropriate moment-to-force ratios: Biomechanical analysis

Abstract

Abstract. Transparent tooth correction treatment is an esthetic alternative to traditional orthodontic treatment. Recently, attachments were introduced in transparent tooth correction treatments to improve the predictability of orthodontic movement. In order to optimize the attachment configuration, the force delivery system of attachments in orthodontic aligner treatment was analyzed. Based on mechanical principles, such as the synthesis theorem of force system, Varignon theorem, and the theorem of force translation, the force system of attachment was analyzed. How the attachments affected the orthodontic treatment was investigated. The attachments' force system F r , F t , M r and M t was determined. The optimum attachment for translation and controlled tipping movement was conceived. The attachments can be designed and placed appropriately to improve tooth movement.

Effect of three different attachment designs in the extrusive forces generated by thermoplastic aligners in the maxillary central incisor

“…4,5 Scientific reports have demonstrated that extrusion movements with aligners are the most difficult ones; 6,7 therefore, the use of movement accessories such as attachments is indicated. 8 Attachments are small structures with well-defined geometry used to generate forces or moments, increasing the capacity of orthodontic aligners to move the tooth 9,10 . Although attachments have great potential, their use in dental practice is restricted because just a few studies have evaluated its mechanical behaviour, [10][11][12] and there is a significant gap of information about the biomechanical performance of these accessories based on their size, geometry, and forces.…”

“…Attachments are small structures with well-defined geometry used to generate forces or moments, increasing the capacity of orthodontic aligners to move the tooth 9 , 10 . Although attachments have great potential, their use in dental practice is restricted because just a few studies have evaluated its mechanical behaviour, 10 - 12 and there is a significant gap of information about the biomechanical performance of these accessories based on their size, geometry, and forces. 9 , 10 Although the study of Dasy et al 11 observed higher retention force for beveled attachments than rectangular or ellipsoid ones, and Cai et al 10 optimized an attachment for tooth translation, no study evaluated the efficacy of attachments for tooth extrusion.…”

Analysis of the influences of bracket and force system in different directions on the moment to force ratio by finite element method

“…When the M/F ratio is low (0-5.6), both the maximum tensile and compressive stress concentrate on apex. With the M/F ratio increased (6)(7)(8)(9)(10)(11)(12), the locations of maximum tensile and compressive stress move from the cervical area to the midroot area on buccal and lingual sides. Figure 7 shows the stress distribution of maximum and minimum principal stresses for the PDL during the uncontrolled tipping (M/F = 0), It is found that there is Orthodontists usually apply orthodontic force and moment to the bracket.…”

“…Zhipeng Liao et al [10] proposed that an M/F ratio of approximately 10.2, 9.7, and 8.8 can generate the bodily movements of maxilla canine, incisor, and first premolar. Cai et al [11] attempted to find appropriate M/F ratio for translation and controlled tipping movement. However, they neglected the influence of a bracket and the direction of external force on the M/F ratio.…”

Optimal Position of Attachment for Removable Thermoplastic Aligner on the Lower Canine Using Finite Element Analysis

“…Eissa et al [9] have found that root resorption in the RTA was significantly lower than the conventional fixed appliances. However, an RTA shows a different orthodontic force compared to arch wire and brackets due to rebound force, making orthodontic treatment difficult in severe malocclusions because it cannot control the movement of the teeth as the orthodontist intended [10,11]. Therefore, in a treatment process using RTA alone, correct orthodontic treatment is not achieved as it is difficult to predict the movement of teeth in the course of the treatment.…”