|Year : 2016 | Volume
| Issue : 5 | Page : 88-93
Precision multiloop (PM Design) with space closing circles for lingual orthodontics
Mugdha P Mankar1, Achint Chachada2, Harish Atram2, Avanti Kulkarni3
1 Asst. Prof., Department of Orthodontics, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra, India
2 Associate Prof., Department of Orthodontics, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra, India
3 Department of Orthodontics, Swargiya Dadasaheb Kalmegh Smruti Dental College and Hospital, Nagpur, Maharashtra, India
|Date of Submission||28-Feb-2016|
|Date of Acceptance||06-Dec-2016|
|Date of Web Publication||18-Jan-2017|
Mugdha P Mankar
52, Netaji Society, Near Friends Colony, Katol Road, Nagpur - 440 013, Maharashtra
Source of Support: None, Conflict of Interest: None
The proficiency of ancient orthodontics has been benefitted colossally and is being continually promoted over the present, by use of multiple loop wires designed for correction of dentoalveolar malocclusions. The presented discussion provides an insight into a simple, frictionless biomechanical concept of anterior space closure in lingual orthodontics by means of precision multiloop design with incorporated space closing circles. A multiple loop wire design has been demonstrated where the entire interbracket distance is used as loop area.
Keywords: Lingual orthodontics, multiple loop wires, precision multiloop design, space closing circles
|How to cite this article:|
Mankar MP, Chachada A, Atram H, Kulkarni A. Precision multiloop (PM Design) with space closing circles for lingual orthodontics. J Indian Orthod Soc 2016;50, Suppl S1:88-93
|How to cite this URL:|
Mankar MP, Chachada A, Atram H, Kulkarni A. Precision multiloop (PM Design) with space closing circles for lingual orthodontics. J Indian Orthod Soc [serial online] 2016 [cited 2019 Apr 24];50, Suppl S1:88-93. Available from: http://www.jios.in/text.asp?2016/50/5/88/198639
| Introduction|| |
Multiple loop wires for correction of dentoalveolar malocclusions have been the cherished systems since the existence of orthodontics. Loop configurations began to be incorporated primarily with an objective to shrink the direct heavy forces from the straight aligning wires. Gradual development into the loop structures paved them a way into almost every stage of orthodontic treatment, from multiple loop initial alignment wires to individual spring designs for extraction space closures. The presented discussion is a revelation to the indisputable prerequisite of the art of wire bending into contemporary orthodontic education and practice, as well as an introduction to an innovative precision multiple loop (PM) design.
Incorporation of a loop increases length of archwire between the brackets resulting in an increase in range of action of the wire and reduction in force. A loop can be contoured as open (e.g., vertical open loop) or closed (e.g., vertical closed loop). An open or continuous loop is activated by compressing the legs and acts by pushing its horizontal extensions apart, thereby increasing the arch length. A closed or reverse loop is activated by compressing the legs and acts by pushing its horizontal extensions toward each other, thereby shortening the arch length. Force produced by a loop may be further reduced by incorporation of coils in the wire at apex; one or more times.
Traditional multiple loop wire preparations are made by arbitrarily increasing the length of wire, i.e., without considering precise discrepancy. Such wire preparations, by and large, tend to produce round tripping during treatment, i.e., frequently the teeth are moved to more than required distances to correct the initial malocclusion and are then aligned back into arches through subsequent wires. For example, an anterior crowded dentition is frequently converted to proclination and spacing, followed by correction of spacing and alignment. To overcome this drawback, a new method is presented which describes preparation of a multiple loop archwire on precise interbracket distances obtained on evaluation of total as well as indigenous space discrepancies. Another characteristic of the new design is that individual loop in the wire occupies the entire interbracket area. A further advantage of the PM design is that it could be applied to both labial as well as lingual orthodontics.
Discrepancy is being conventionally derived as the difference between the tooth material between the first permanent molars (the required arch perimeter) and estimated arch space which is present mesial to the first permanent molars (the available arch perimeter) (available arch perimeter − required arch perimeter = discrepancy in arch perimeter).
An important consideration here, which the authors would like to introduce, is the required tooth material. The term required tooth material shall henceforth refer to the amount of tooth material required to be contained in a precisely derived required arch perimeter and shall follow the keys to normal occlusion. This could be achieved if consideration be given to Bolton discrepancy in the formula for arch perimeter.
In this instance,
Discrepancy in arch perimeter − Bolton discrepancy = derived discrepancy (to be corrected).
Required arch perimeter − Bolton discrepancy = derived required arch perimeter or required tooth material.
| Derivation of Total Length of the Multiple Loop Wire by Considering the Total Space Discrepancy|| |
Three possible clinical situations have been considered.
Dental arches with space compensated discrepancies
Clinical situations where various indigenous discrepancies (individual tooth malpositions) are present, but their summations cancel out the space problem. In addition, no Bolton discrepancy exists. The total space discrepancy thus equals to zero.
For example, spacing + crowding, spacing + rotations, and spacing + proclination with no Bolton discrepancy. So,
*Length of the multiple loop (ML) wire in mm = **Equals to available arch perimeter for wire
= ***Equals to tooth material in wire.
Dental arches with spacing
Clinical situations where arch perimeter is more and/or tooth material is less, Let, (x) = arch perimeter tooth size discrepancy, i.e., arch perimeter is x mm more than tooth material or tooth material is x mm lesser than arch perimeter, If an added Bolton discrepancy exists in the above situation, let (y) = amount of space to be retained for increasing the tooth size prosthetically (here, required tooth material > available tooth material), so the amount of space discrepancy to be corrected orthodontically becomes (x − y).
So, depending on the existence of above situations,
*Length of the ML wire in mm = **Equal to (x) mm lesser or (x − y) mm lesser than available arch perimeter for wire = ***Equal to or (y) mm more than tooth material in wire.
Dental arches with crowding
Clinical situations where available arch perimeter is less and/or tooth material is more, let (x) = compensatory increase in arch perimeter possible to correct the discrepancy without reduction in tooth material (arch perimeter is x mm lesser than tooth material or tooth material is x mm more than arch perimeter; in the absence of an added Bolton discrepancy).
If an added Bolton discrepancy exists in the above situation, let (y) = possible reduction in tooth material, for example, interproximal stripping, so the amount of space discrepancy to be corrected orthodontically becomes (x − y).
So, depending on the existence of above situations,
*Length of the ML wire in mm = **Equals to (x) mm more than available arch perimeter for wire or (x − y) mm more than available arch perimeter for wire = ***Equals to tooth material or (y) mm less than tooth material in wire.
(*Length of the ML wire in mm is calculated from distal ends of bracket slots on last teeth included in the wire.
**Available arch perimeter for wire is the part of arch perimeter mesial to the distal ends of bracket slots on last teeth included in the wire.
***Tooth material in wire is the part of tooth material of all teeth included in the wire present mesial to the distal ends of bracket slots on last teeth included in the wire).
Note: PM-design allows the use of molar stops in contrast to traditional multiple loop wire where they are contraindicated. "Total space discrepancy equals the summation of indigenous space discrepancies."
A simple example is shown with indigenous space discrepancies and no Bolton discrepancy.
The indigenous space discrepancies are as follows,
S = Spacing between 12 and 11 = 1 mm, between 11 and 21 = 2 mm (total spacing = 3 mm),
R = Space required for rotation correction in 12 = 2 mm, in 22 = 1 mm (total rotation/crowding = 3 mm).
Therefore, a space compensated discrepancy exists, where space required for rotation correction is equal to space available.
Therefore, total length of wire = available arch perimeter for wire = tooth material in wire.
Multiple loop wire fabrication for the malocclusion example
- Horizontal dimension (width) of the loop between 11 and 21 equals 2 mm less than the interbracket distance between 11 and 21, for the correction of spacing
- Horizontal dimension (width) of the loop between 11 and 12 equals 1 mm more than the interbracket distance between 11 and 12.(2 mm space required for rotation correction, 1 mm space available, and 1 mm activation in loop provides for mesial movement of 11 and space creation)
- Horizontal dimension of the loop between 21 and 22 equals 1 mm more than the interbracket distance between 21 and 22 (1 mm space required for rotation correction, no space available, and so 1 mm activation in loop provides for mesial movement of 21and space creation)
- Space closing circles can be incorporated in the loops to further facilitate the tooth movement. Number of circles in the loop could be increased to two if more than one to two mm space is being closed [Figure 1]a and b.
|Figure 1: (a) One space closing circle in loop design, (b) two space closing circles in loop design|
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| Case Report|| |
A 22-year-old female reported to the Department of Orthodontics and Dentofacial Orthopedics, with a chief complaint of spaced anterior dentition. On clinical examination, an Angle's Class I Type 2 maloclusion was recognized, with proclination and spacing in anterior teeth. Full complement of teeth till the permanent second molar was present in both the arches. Rotations were present in maxillary lateral incisors and mandibular premolars. The facial profile was pleasing [Figure 2].
Cephalometric analyses revealed a Class II skeletal relationship; maxilla as well as mandible was forwardly placed. Patient had an average growth type and both maxillary and mandibular incisors were proclined [Table 1].
Study models revealed a space compensated discrepancy (malocclusion example), i.e., space available in the arch as a result of spacing was compensated by space required for the correction of rotations.
Facial profile of the patient was impeccably pleasing, and this guided toward the decision of nonextraction even after considering the furthered proclination of anterior teeth as well as the inherent Class II skeletal relationship. Treatment objectives were eventually determined as closure of spaces and correction of presented rotations.
Patient opted for an invisible appliance, so a lingual appliance was prescribed. STb Lingual System was used with a 0.022 inches bracket slot. PM design was fabricated as described in the malocclusion example. [Figure 3] shows the design and ligation of the multiple loop wire with space closing circles incorporated in the loop design, prepared from an 0.016 inches round stainless steel (SS) which was heat treated after complete fabrication for stress relaxation.
During ligation of the wire in areas of severe discrepancies (rotations) loose ties were provided, to curtail the amount of force acting on the tooth. During the subsequent appointments, more precise ligations into the bracket slots were done progressively. The technique thus provided correction of entire discrepancy with a single multiple loop wire.
Space closure was observed after 3 months, when a plain mushroom archwire in 0.016 inches round SS was ligated after heat treatment. During finishing of the occlusion, bends as required were gradually incorporated in an 0.016 inches round SS wire, in consecutive appointments. [Figure 4] shows the finished occlusion after debonding.
Comparison of the pre- and post-treatment lateral cephalometric radiographs and their superimpositions has been shown in [Figure 5] and [Figure 6], showing improvement in incisor proclination and lip profile.
|Figure 5: Pretreatment cephalogram (left), posttreatment cephalogram (right)|
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|Figure 6: Ricketts superimposition (a: chin, b: maxilla, c: maxillary incisor and molar, d: mandibular incisor and molar, and e: soft tissue)|
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| Discussion|| |
Lingual appliance observes a reduced interbracket distance. The wire thus becomes several times stiffer as compared to the same wire when used with a labial appliance., The resultant reduction in the range of activation as well as constancy of force has been a reason for the use of resilient wires with reduced modulus of elasticity or lesser cross-section wires.,
Previous literature provides enormous documentation on multiple loop wire structures having been used for occlusal corrections in labial orthodontics., The field of lingual orthodontics has, however, witnessed the use of loops simply for extraction space closures and a sparse usage during alignment. Documentation in the previous literature expressing difficulties in introduction of multiple loop archwires with lingual appliance has been revealed; relating them to the small interbracket distance in the appliance. This may well be the reason for zone of anterior space closure in lingual orthodontics has been largely governed by the elastomerics. Since these are also being used for ligations, there has been an indication in the literature of an impression that tooth movement slows down because of the friction generated by the dual elastic force on a single tooth, i.e., presence of space closing elastomeric chains and the elastic overties. Thus, elucidating a demand for alternative wire preparations to speed up the orthodontic treatment.
An innovative multiple loop wire design which has been introduced, where the entire interbracket distance is used as the loop area, i.e., vertical legs of all the incorporated loops shall start immediately from the proximal ends of bracket slots. In other words, length of the horizontal portion of the wire between any two loops shall be only and exactly equal to the mesiodistal dimension of the bracket slot present between the concerned loops. This has led to an immense increase in the range of action of the wire.
Supporting the presented concept are previous studies on the effect of dimensional change of vertical loops which have suggested that increasing the loop height and width, results in reduction in loop stiffness in vertical as well as radial directions.
Width of an individual loop has been derived as the precise corrected interbracket distance while the length has been taken as 6 mm. The following discussion justifies the same. Distance between the point of application of force and center of resistance of tooth is reduced in the lingual technique. This distance as calculated from the cingulum to the center of resistance has been reported as 6.4 mm., Space closing circles have been incorporated to increase the range of action at the loop bases. Irritation to the tongue caused by the additional wire structure was expected to be less (and confirmed on clinical observation) as compared to traditional vertical loop designs owing to the wide bases which conform the total interbracket dimensions.
The PM design is hereafter primed for further exploration and in all probability shall enhance the contemporary knowledge on orthodontic wire preparations.
| Conclusions|| |
PM design provides a simple, frictionless mechanism for correction of malocclusion by a single multiple loop wire. In the era of precision, knowledge of discrepancy elucidating a precise wire preparation shall facilitate the treatment in varied aspects.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]