Intrabracket space and interbracket distance: Critical factors in clinical orthodontics

doi:10.1016/0889-5406(89)90347-8

American Journal of Orthodontics and Dentofacial Orthopedics

Volume 96, Issue 4, October 1989, Pages 281-294

https://doi.org/10.1016/0889-5406(89)90347-8 Get rights and content

Abstract

The engineers who designed the Houston Astrodome, Walter Moore and Associates, were engaged to study the effect that different edgewise appliances have on the function of orthodontic beams or wires. They were supplied with tooth width, bracket width, wire size, slot size information, and stainless steel wire specifications. With these data their computer was programmed to model each appliance as a simple beam reflecting its different support conditions. In the study the 0.018, 0.022, and 0.016-inch traditionally slotted appliances were tested in single and twin brackets. In addition the 0.016-inch bimetric appliance (0.016 inch on anterior teeth, 0.022 inch on posterior teeth) was tested. The following wires were used for testing: 0.016 × 0.022 inch, 0.017 × 0.022 inch, 0.018 × 0.025 inch (0.018 inch); 0.018 × 0.025 inch, 0.019 × 0.025 inch, (0.016 inch and bimetric). The results as stated in the conclusion statement by Rick Horn, PhD, of Walter Moore and Associates, are 91) for a given appliance and wire size, the amount of deflection allowable at permanent set decreases with decreasing size of teeth; (2) for a given appliance and wire size, the force imparted to the teeth at permanent set increases with decreasing size of teeth; (3) for a given appliance, the amount of deflection at permanent set decreases with increasing wire size; (4) for a given appliance, the force imparted to the teeth at permanent set increases with increasing wire size; (5) the amount of deflection allowable at permanent set is larger for single brackets than double brackets and larger for bimetric brackets than single brackets; (6) the force imparted to the teeth at permanent set is smaller for single brackets than double brackets and smaller for bimetric brackets than single brackets; and (7) of the six types of appliances examined, the bimetric appliance is the most flexible, allowing the most deflection at permanent set with the smallest force imparted to the teeth. This study supports the following thesis: the only way to take advantage of smaller wires and thereby have an appliance deliver maximum resiliency with lighter forces and not loose control is through differential slot sizing.

References (7)

R.C. Thurow
Edgewise orthodontics
(1982)
T.D. Creekmore
Physiologic drift
J Clin Orthod
(1975)
R.M. Ricketts
Denver: Seventy-second annual session of AAO
(1971)

There are more references available in the full text version of this article.

Cited by (15)

3-dimensional finite element analysis of the outcomes of Alexander, Gianelly, Roth and MBT bracket prescription
2019, International Orthodontics
Citation Excerpt :
Torque is used to change the inclination of teeth, and it has a vital importance for achieving maximum aesthetics, function and stability of the orthodontic treatment results [1]. The degree of change in the buccolingual inclination of teeth depends on the bracket slot, bracket design, type of bracket system, play between bracket slot and wire, wire dimension, stiffness of wire, interbracket distance and mode of ligation [2–6]. The wide range of these combinations makes the torque of the anterior teeth a difficult decision for the specialist.
The purpose of this study was to compare the effect of a 4-bracket system including Alexander, Roth, MBT (Maxillary Transverse Bioadaptation), and Gianelly on the upper anterior tooth movement in sliding mechanics with the help of a 3-Dimensional (3D) Finite Element Method.
Displacement, stress, strain, centre of rotation and resistance on the incise edge and apex of the maxillary central incisor were calculated when 100, 200, 300, 400 grams of retraction force were applied.
The amount of incise edge displacement was 2.609 × 10⁻⁴ mm 2.682 × 10⁻⁴ mm 2.875 × 10⁻⁴ mm and 2.881 × 10⁻⁴ mm in Alexander, Gianelly, Roth and MBT respectively with 100gr of retraction force. The value of apex root movement was 3.485 × 10⁻⁴ mm 3.547 × 10⁻⁴ mm 3.852 × 10⁻⁴ mm and 3.864 × 10⁻⁴ mm in Alexander, Gianelly, Roth and MBT respectively with 400 g of retraction force.
The MBT system had the maximum apex root and incisal edge movement in all 100, 200, 300, 400 grams of retraction force. The Alexander system had the lowest apex and incisal edge movement in all retraction forces.
Le but de cette étude était de comparer l’effet d’un système de 4 attaches en technique Alexander, Roth, MBT (Maxillary Transverse Bioadaptation) et Gianelly avec mécanique de glissement sur le déplacement des dents antérieures maxillaires à l’aide de la méthode des éléments finis tridimensionnelle (3D).
Le déplacement, la contrainte, la déformation, le centre de rotation et la résistance sur le bord incisif et l’apex de l’incisive centrale maxillaire ont été calculés après application de force de rétraction de 100, 200, 300 et 400 g.
Au total, le déplacement du bord incisif a été de 2,609 × 10⁻⁴ mm, 2,682 × 10⁻⁴ mm, 2,875 × 10⁻⁴ mm et 2,881 × 10⁻⁴ mm respectivement selon les techniques Alexander, Gianelly, Roth et MBT avec une de force de rétraction de 100 g. La valeur du mouvement de l’apex a été de 3,485 × 10⁻⁴ mm, 3,547 × 10⁻⁴ mm, 3,852 × 10⁻⁴ mm et 3,864 × 10⁻⁴ mm respectivement selon les techniques Alexander, Gianelly, Roth et MBT avec 400 g de force de rétraction.
Le système MBT a eu le mouvement de version de l’apex et du bord incisif le plus grand, que la force de rétractation soit de 100, 200, 300 ou 400 g. Le système Alexander a eu le mouvement de version de l’apex et du bord incisif le plus faible quelle que soit la force de rétraction appliquée.
Wire load-deflection characteristics relative to different types of brackets
2011, International Orthodontics
Citation Excerpt :
The results of this study demonstrate the importance of interbracket distance in determining the load of a wire on a single tooth. According to the study by Schudy and Schudy [12], the deflection of an orthodontic wire is directly proportional to the interbracket distance and inversely proportional to the wire cross-section. The delivered force increases with decreasing tooth size.
To test the hypothesis that the dimension of the bracket, both in labial and in lingual orthodontics, is a relevant parameter to determine the forces acting on the teeth, and that some wires commonly used in labial orthodontics (0.016”-diameter SS, TMA and Nitinol) are not suitable for the first phase of lingual treatment.
An ideal dental cast was bonded with eight different brackets (Damon 3MX, Ovation, Time 2, Innovation and Smart Clip Clarity on the vestibular face; STB, Adenta Time and Innovation-L on the lingual). After photographic documentation, the interbracket distance was calculated for each type of bracket, using ImageJ software. The mean elasticity modulus of the tested wires was obtained from the review of the available literature. The theoretical wire load on every tooth was calculated mathematically at three different levels of deflection (0.5 mm; 1.0 mm and 1.5 mm), on both the labial and lingual sides, for all types of bracket.
The lingual arch in the anterior segment is always shorter than the vestibular arch. The different brackets, having different dimensions, have an influence on the interbracket distance, and, consequently, on the wire load. At large deflections, superelastic NiTi expresses light and continuous forces, which are significantly lower than the other examined alloys.
The initial hypothesis was supported. Because of the reduced interbracket distance, the adoption of superelastic wires is required in lingual mechanics and with smaller diameter compared to labial mechanotherapy, in particular during the first phases of treatment. The use of a bracket with reduced mesiodistal dimensions can contribute to reduce the load on the teeth.
Relative friction minimization in fixed orthodontic bracket appliances
1996, Journal of Biomechanics
The biomechanical and mathematical analysis of friction on an arch wire/bracket combination and the wire supports has demonstrated that there is an optimal relationship, i.e. minimal friction forces, between the bracket width and the distance between the adjacent brackets on the neighboring teeth. With this optimal situation, less force will develop for a given deflection of the arch wire. This, in turn, will lead to fewer frictional effects when the friction forces are assumed to be proportional to the concentrated perpendicular forces on the arch wire. As long as the contacting surface can be regarded as a point, Coulomb's law of friction can be applied in its simplest form. Relative friction minimization can thereby be qualitatively and quantitatively obtained by linear theory for any specified angulation, wire properties and coefficients of friction. Literature stating that narrow brackets will lead to less friction for specified angulation cannot be confirmed according to the presented analysis. The other extreme statement ‘Use the widest bracket possible’ also cannot be used in principle. Since the analysis shows a mathematical relationship between most of the relevant design variables of an arch wire/bracket combination and the magnitude of friction forces, empirical results can be sorted and ranked by their physical figures instead of by statistical distribution. In addition, it is possible to make recommendations about the appropriate bracket sizes for various cases. The dependences of the coefficients of friction themselves on material, surface roughness, lubrication, etc. are not investigated here. These factors are also very relevant, especially in reduction of the absolute magnitude of frictional forces, but this problem is left to tribologists.
Bending stiffness of two aesthetic orthodontic archwires: An in vitro comparative study
1994, Clinical Materials
The aims of the study were to quantify the transverse stiffness of two aesthetic orthodontic archwires (0·018 inch Teflon-coated stainless steel and 0·017 inch Optiflex) in a simulated clinical setting and to assess the influence of deflection direction on the bending stiffness. The aesthetic archwires were randomly divided into three equal groups: group 1, lingual deflection; group 2, labial deflection; and group 3, occlusal deflection. Each group consisted of six archwires of the same type. The control group consisting of eighteen 0014 inch stainless steel archwires were also subjected to the same grouping. A total of 54 archwires were tested in the study. The deflection of the archwires was measured with a travelling microscope and the load measured with a calibrated strain gauge ring transducer. The mean stiffnesses of the archwires in the lingual, labial and occlusal deflection groups were found to be 2·9, 0·8 and 2·5 mN/mm respectively for 0·017 inch Optiflex (r = 0·9, P < 0·001), 13·2, 10·5 and 24·5 mN/mm respectively for 0·018 inch Teflon-coated stainless steel (r = 0·9, P < 0·001) and 26·6, 16·4 and 32·3 mN/mm respectively for the control (r = 0·9, P < 0·001). Springback was found to be poor for Optiflex and the archwire remained bent upon deactivation. ANOVA showed that the influence of arch curvature on the bending stiffness was significantly different for Optiflex (P < 0·05), Teflon-coated stainless steel (P < 0·005) and the control group (P < 0·005). Stiffness for the Teflon-coated archwire was found to be higher and more in line with the stiffness for the control. Both the Teflon-coated and stainless steel archwires displayed good springback property. However, Optiflex was found to have low stiffness and resilience. Owing to the poor springback, the clinical efficacy of Optiflex is probably limited.
The influence of bracket design on moment production during axial rotation
1993, American Journal of Orthodontics and Dentofacial Orthopedics
The interaction between the bracket of an axially rotated tooth and arch wire produces a moment. This moment influences tooth movement and rotational control and is itself influenced by bracket width and bracket ligation. Self-ligating spring clip brackets fasten to and interact with arch wires differently than conventionally ligated brackets. An in vitro study with a simulated orthodontic model was undertaken to evaluate the effects of bracket width and ligation technique on the moment production of conventional and self-ligated brackets during axial rotation. Bracket widths ranged from 1.890 mm (0.0744 inch) to 2.809 mm (0.1106 inch). Steel tie, elastomeric, and self-ligating spring clip ligation techniques were used. Empirically, both bracket width and ligation technique significantly effect the moment produced during axial rotation. For the range of bracket widths and types evaluated, ligation technique was found to have a greater influence on moment production than did bracket width. The self-ligated spring clip bracket delivered the least force over the greatest range of axial rotation.
Change in crown inclination accompanying initial tooth alignment with round archwires
2022, Dental Press Journal of Orthodontics

View all citing articles on Scopus

View full text

Original articleIntrabracket space and interbracket distance: Critical factors in clinical orthodontics

Abstract

Edgewise orthodontics

Physiologic drift

J Clin Orthod

Denver: Seventy-second annual session of AAO

Original article
Intrabracket space and interbracket distance: Critical factors in clinical orthodontics