Ribbon-wise customized lingual appliance and orthodontic anchor screw for the treatment of skeletal high-angle maxillary protrusion without bowing effect

Lever arm on bracket vs. lever arm on archwire: A 3D finite element method study of mechanics of miniscrew-supported lingual en-masse retraction of maxillary anterior teeth

OBJECTIVE

To compare the deformation of the main archwire and 3D movements of maxillary anterior teeth during miniscrew-supported en-masse retraction with the lever arm on the archwire and on the brackets in lingual orthodontic treatment in finite element analysis (FEM) simulation.

MATERIAL AND METHODS

A 3D dental-alveolar model with bonded 0.018×0.025-inch slot lingual brackets and a 0.017×0.025-inch dimension stainless-steel archwire was created. Four FEM models were created based on a 3D dental-alveolar model: in Models A and C, the lever arms were attached to the lingual bracket, while in Models B and D, the lever arms were attached to the archwire. Meanwhile, in Models A and B, the miniscrews were placed in between the molars, while in Models C and D, the miniscrews were positioned on the palatal roof. After a 1.5N retraction force was applied from the miniscrew to the end of the lever arm, the initial movements in the sagittal, transversal, and vertical planes were recorded and analysed for maxillary anterior teeth.

RESULTS

In Models B and D, smaller deformation of the main archwire and less prominent bowing effect were noticed in both sagittal and vertical directions compared to their counter groups. In Models C and D, the central incisors showed less torque loss in the sagittal direction and more canine intrusion vertically.

CONCLUSIONS

For the same lever arm-miniscrew retraction configuration, the lever arm on the bracket showed less deformation of the main archwire and more body movement of the teeth than the lever arm on the archwire group. With the same level arm height, the transverse and vertical bowing effect is reduced when the lever arm was placed distal to the central incisor and the miniscrews placed next to the palatal suture.

Torque control with set-up and auxiliary spring in an adult severe class II case treated by lingual straight-wire appliance, premolar extractions and orthognathic surgery

This case report describes a complex full-step class II high angle case in an adult patient treated with lingual straight-wire appliance, premolar extractions and orthognathic surgery. With the twofold aim of obtaining ideal occlusal relationship and aesthetic improvement, surgical treatment with appropriate biomechanical strategies, including extraction choice and torque control during space closure, are needed to achieve the planned results. This case report demonstrates the possibility of solving successfully severe sagittal, transverse and vertical discrepancies in an adult patient with surgical treatment by means of an invisible technique. This report also underlines the need for precise biomechanical control, including set-up overcorrections and an auxiliary spring to manage teeth inclination, in lingual orthodontics extraction cases.

Digital lingual appliance combined with micro-screws for the treatment of a skeletal bimaxillary protrusion and ‘gummy’ smile

This case report describes the lingual orthodontic treatment of a 28-year-old female patient who presented with a bimaxillary protrusion malocclusion, a hyperdivergent facial pattern, mentalis strain, and a ‘gummy’ smile. To achieve favourable occlusal and facial results, the four first premolars were extracted, and micro-screws utilised to provide maximum anchorage. With the widespread application of three-dimensional technology, a digital goal-oriented treatment plan was applied for its predictability and precision. A fully customised lingual appliance system with preset torque in the anterior teeth combined with ribbon-wise arch wires was placed to prevent excessive lingual inclination of the incisors during retraction. As a result, an attractive facial profile and a well-aligned dentition with ideal intercuspation was obtained.

The Effect of Ligature Type on Lateral Tooth Movement during Orthodontic Treatment with Lingual Appliances—An In Vitro Study

(1) Background: One of the most challenging parts in lingual orthodontics is the control and correction of the tip of anterior teeth, due to the occlusal open vertical slot of the incisors in lingual systems. The presented experimental in-vitro study was performed to determine the maximal tipping moment of the anterior teeth between two types of lingual brackets, the Incognito™ Appliance System (Incognito, TOP-Service, Bad Essen, Germany) and Tip-Bar™ system (Incognito, TOP-Service, Bad Essen, Germany). Furthermore, twelve different ligation methods and two different ligature materials were investigated. (2) Methods: The measurement was performed by assessing the stiffness and ultimate strength of the ligature in a uniaxial material testing machine (Instron, Norwood, MA, USA) using a 0.025 × 0.018 inch stainless steel wire. (3) The results showed that the highest precision for control tipping of anterior teeth was determined for the 0.010 inch Stainless Steel Tie (Pelz and Partner). Furthermore, the Tip-Bar™ brackets increased the maximal moment by 33.8% for elastic and steel ligatures. (4) Conclusions: The lateral tooth movement is highly dependent on the type of ligature and applied material during orthodontic treatment with lingual appliances. The use of 0.010 inch steel ligatures and the Tip-Bar™ bracket design results in better alignment in the anterior teeth segment.

A Comparison of the Ligation Torque Expression of a Ribbonwise Bracket-Archwire Combination and a Conventional Combination: A Primary Study

OBJECTIVE

To assess the effect of the third-order mechanics of a new ribbonwise bracket-archwire combination using an orthodontic torque simulator. Material and Methods. An orthodontic torque simulator was used to measure the third-order moment of a maxillary central incisor as it changed from a neutral position to a 40° rotation in 1° increment. A new ribbonwise bracket (Xinya, China) was compared with a conventional ligation bracket (American Orthodontic, U.S.A.). The effects of different archwire sizes (i.e., 0.017″ × 0.025″ and 0.019″ × 0.025″) and materials (i.e., nickel-titanium, titanium-molybdenum alloy, and stainless steel) were analyzed. Paired sample t-tests were conducted to compare the moments between the two bracket types corresponding to each of the archwires. The effects of the stiffness of the bracket-archwire complexes were also assessed.

RESULTS

Statistically significant differences (P=0.05) between the moments from the two brackets were found. The ribbonwise bracket-archwire complex generated larger moments when the rotation angle was lower than 30°. The ribbonwise brackets produced moments that could reach a threshold of 5 Nmm more quickly as the angle was increased. The higher the stiffness of the complex, the larger the moment.

CONCLUSION

The ribbonwise bracket-archwire complex reached the moment threshold limits earlier than the conventional complex. When the rotation angle is less than 30°, the ribbonwise bracket-archwire complex generated a greater torque moment in comparison with the conventional complex.

The cross-sectional effects of ribbon arch wires on Class II malocclusion intermaxillary traction: a three-dimensional finite element analysis

BACKGROUND

The application of intermaxillary traction is often accompanied by the unexpected movement of dentition, especially anchorage teeth. The aim of this study was to comprehensively compare the influence of cross-sectional shape of ribbon arch wires with edgewise and round wires on intermaxillary traction in Class II malocclusion treatment using FEA simulation.

METHODS

The dentofacial structure was simulated in finite element software. A retraction force of 1.5 N was applied to different cross-sectional orthodontic arch wires: a ribbon wire (0.025 × 0.017-in. and 0.025 × 0.019-in.), a rectangular wire (0.017 × 0.025-in. and 0.019 × 0.025-in.) and a round wire (Φ 0.018-in. and Φ 0.020-in.).

RESULTS

Among the three groups, ribbon wire (0.025 × 0.017-in. and 0.025 × 0.019-in.) exhibited the lowest displacement in the X-axis (12.61 μm and 12.77 μm, respectively) and Z-axis (8.99 μm and 9.06 μm, respectively). However, the 0.025 × 0.017-in. ribbon wire showed the highest Y-axis displacement. In the round wire group, Φ 0.020-in. wire displayed less rotation than Φ 0.018-in. wire, where the sagittal, frontal and occlusal rotation of Φ 0.020-in. wire was almost half of that of Φ 0.018-in. wire. The movement of the first molar region was intermediate between the ribbon arch group and the round wire group. Notably, the values of the 0.025 × 0.017-in. arch wire displacement, which were higher than those of any other group, peaked at 0.019 mm in the central incisor region with a spike-like shape. The deformation range of the Φ 0.018-in. wire group was the largest in this study.

CONCLUSIONS

The cross-section of the arch wire influenced force delivery in Class II intermaxillary traction. With the same shape, a larger cross-sectional area led to less mandibular dentition movement. For the rectangular arch wire and ribbon arch wire groups, since the height and width were inverted, the vertical displacement of anchorage teeth in the ribbon wire group was reduced, but the possibility of buccal tipping in mandibular anterior teeth also increased.

Comparative study of effect of different lever arm positions and lengths on transverse and vertical bowing in lingual orthodontics - An FEM study

OBJECTIVE

To assess the influence of changing the size and position of lever arm on transverse and vertical bowing effects during retraction in lingual biomechanics.

METHODS

A three dimensional 3D finite element method was used to simulate en masse anterior teeth retraction using lingual appliance with sliding mechanics. Two groups were made, 1st group had lever arm mesial to canine while 2nd group had distal to canine. Each group had 4 subgroups with lever arm height varying from 0mm to 12mm. Displacements of the maxillary anterior teeth were noted in each group.

RESULTS

As the Lever Arm Height (LAH) increased in group I, the vertical bowing effect reduced while the transverse bowing increased with respect to canines. In group II, both vertical and transverse bowing effects increased but transverse bowing was less as compared to group I.

CONCLUSION

Strategic location of the lever arm is required in different clinical situations during en-mass retraction, keeping in mind the location of Centre of Resistance (CRes) as well as the vertical and the transverse bowing effects.

Quality in orthodontics: The role of customized appliances

Orthodontics as well as dentistry are undergoing a technological revolution with advances in medical imaging, 3D printing and customization of appliances and devices. Digital orthodontics can be defined as the process of manufacturing customized appliances based on a target setup which incorporates tooth positioning in six-degrees-of-freedom. Three-dimensional medical imaging provides better diagnostic tools and allows for fabrication of orthodontic appliances based on the coordinates system of the occlusal plane within the facial anatomy. This article describes the state-of-the-art in goal-driven orthodontic treatment, warns against the commercialization of our profession, and highlights the advantages of lingual orthodontics in terms of protection of the enamel.