Separators in Orthodontics : A Review

Placement of bands on the posterior teeth are preferred to bonding due to heavy masticatory forces. Placement of bands needs interdental separation of 0.2 mm, which requires prior placement of separators for couple of days. Various types of separators are commercially available in the market, with their own advantages and disadvantages. A scientific review of this most useful armamentarium in orthodontics was lacking and therefore a search was undertaken to gather information on separators. This article deals with various aspects of separators in detail Review Article


INTRODUCTION
Placement of bands in posterior region is preferred over bonding, as posterior teeth experience larger masticatory force than the anteriors. The average periodontal ligament (PDL) space is 0.25 mm and placement of a 0.16 mm thick metal band without proper tooth separation can lead to contraction of the alveolar bone which in turn shall produce hyalinization areas in the PDL 1 and evoke pain. 2,3 Separation of teeth to create interproximal space is the first step in banding. 4 It is important to remember that, as separator placement is the done in the first appointment a painless procedure proves to be an important step in building trust with the patient. Separation is an orthodontic procedure aiming at slightly loosening the tight interproximal contacts between teeth to create space for the fitting of orthodontic brands by forcing or wedging the teeth apart usually for one week. 5 Orthodontic separators though used daily in orthodontic practice is the least researched auxiliary till date.

History of Separators
In 1907, Angle first discussed the need to separate the teeth for placement of bands. He used brass wire for this purpose.
The brass wire was passed under the contact point, then carried on over the contact. The two ends of the wire were then tightly twisted together and tucked into the interdental area. He stated "Such a ligature will not give annoyance from displacement so liable in the use of wedges, and if worn a few hours, it will be found that ample space has been gained for the accommodation of the band." 6 In 1921, Calvin Case advocated the use of separating tape, which was flax waxed tape wrapped around the contact. He said that the tape should be left on for only 24 hours and then changed if separation was insufficient. 7 Oliver 8 explained the reasons for separation in the following manner. • To reduce physical pain to the lowest possible degree.
• To prevent injury to the tooth structure from excess pressure.
• To reduce physical and mental tension of the patient by having the band material conveniently carried to place.
• To prevent distortion of the band material by not having to force it unduly to position during band construction.
Graber 9 suggested that duration of the placement of separation should be as per the personal preference.
However, no mention was made about the length of time the separators are to be placed or amount of space that has to be gained.
Thurow 10 was the first to mention rubber separators. He considered its use when rapid separation is required. He suggested to remove these separators as early as possible.
He suggested that the action of these separators is not selflimiting and its extended placement should be avoided.
The Begg technique introduced separating springs. Anderson used it for rapid separation within few hours. Begg used these separators for few days. Begg suggested that the springs should be left in place till the discomfort ceases; whereas they should not be left for so long that they fall off on their own. 11 The initial elastomer used was natural rubber (or caoutchouc) collected from the sap of Heveabrasiliensis tree. Elastomer is a general term that includes macromolecular material, which after deformation returns to its original dimensions. 12 The natural rubber was of less use until the introduction of the McGann in 1991. 15 Brosius and Sim introduced rectangular wire separator using the same principle in 1994. 16 The most recent separator is Kansal separator introduced by Kansal in 2012. It is a self-secured two-in-one separator of an advantage of no dislodgement; carrying out separation on both mesial and distal aspects simulatenously. 17

Ideal requirements of separators
The separator should provide adequate separation for proper band fitting and yet comfortable to the patient. It should be easy to insert in tight contacts without breakage during the insertion. It Should not dislodge while chewing food and remain till it is removed by the orthodontist. 18,19 It should be autoclavable and hygienic; and should not make teeth sensitive to band seating pressure. It is passed around the tooth contact and the ends are twisted tightly together using Mathieu pliers or hemostat. The end is made short (about 3mm) and then tucked between the teeth. The separating force created is based on the patient's response or clinician's experience.

Uses of separators
These separators are easy to place as no special instrument is required for its placement and removal. However they have poor patient acceptance as they may irritate the soft tissue.

Dumb-bell shaped separator
Dumb-bell shaped (Mexican) elastic separator is dumb-bell in shape. This type of separator resembles a wide rubber band with thick rolled edges. They are obtained in strips and cut to size by the operator to accommodate various teeth.
It is stretched and passed through the contacts between adjacent teeth. These separators are used for carrying out rapid separation. They are recommended to be placed 30 minutes before band fitting, but can be painful to the patient.
Special pliers are not required for its placement. 25

Elastic ring separator (Donut separator)
Small elastic rings made up of polyurethane are used for separation. Rings of varying thickness are placed around the

Safe-T separator
These are ring separators with additional knob on either side of each ring. They extend beyond the interproximal area over the gingiva thus preventing the separator from submerging into the sub-gingival area. They are available in two designs: viz standard (purple) and slim (blue). 26 The slim separator is thinner with less force requiring only minimal space as in anterior region.

Kansal separator
It is also known as "2-in-1" self-secured orthodontic spring separator ( Figure 3). It is a single separator which separates both mesial and distal aspects of tooth simultaneously, individually, yet efficiently. It has a self-locking connecting bar Kansal separators are the most beneficial to the patient as they greatly reduce patient appointments, are highly comfortable, cause no gum swelling and reduced pain.

Pain associated with separators
Ngan et al 27   Bondemark et al 28 obtained the mean separation of 0.3mm from spring type and 0.4mm from elastomeric separators and they concluded that the separation effect of two separators was clinically equivalent.