Methods for enamel reduction

Interproximal tooth reduction is a common practice in orthodontic treatment whether it is in conjunction with fixed or clear plastic appliances. Known by many terms such as slenderizing, stripping, or reproximation, IPR is done by reducing the mesiodistal dimensions of the teeth and is intended to improve tooth alignment. By maintaining enough space, orthodontists attempt to resolve moderately crowded dentitions or change teeth morphology in a way to better malocclusion.

While the process of enamel reduction sounds fairly uncomplicated, there are certain key principles that are required to be followed in order to minimize damage to the teeth and associated tissues. It is now widely accepted that 50% of the proximal tooth enamel is the maximum limit to be stripped without causing dental and periodontal risks.

Principles of tooth stripping

According to a report in the Journal of Dentofacial Anomalies and Orthodontics, the fundamentals of tooth stripping as proposed by Sheridan and Fillion are:

• Do not reduce tooth enamel before bonding attachments to the tooth.
• Fully align rotated teeth before stripping them.
• Do not strip all the teeth in a single appointment.
• Separate the teeth, by putting separators in place on a previous appointment, before stripping them so as to improve access
• Always strip from the posterior to the anterior to prevent any loss of the space being gained from slippage.
• Always protect adjacent soft tissue with cotton rolls and wooden wedges.
• Always reshape the stripped teeth to their proper form and restore the remaining enamel surface to its original smoothness, polishing being essential.
• Prescribe a fluoride solution that patients can use to increase the potential for remineralization

Techniques of enamel reduction

Stripping techniques include the use of one of the following instruments:

• Diamond discs

These discs are covered with standard or extra-fine diamond grains on one or both surfaces.

Diamond discs of thickness 0.1 mm are mounted on a blue ring contra-angle and used to remove the enamel. The orthodontist then uses round or triangular diamond burs (#8833, Komet) to round off any angularities left on the enamel surface.

However, it is important to exercise caution when using diamond discs, especially at high speed because they can injure the patient’s tongue, cheeks, or lips.

• Burs

Special burs with “deactivated” points (IDEAL burs) can also be used to strip the tooth enamel. These burs are relatively safer than diamond discs in the sense that they will not create ridges in the proximal enamel. Tungsten carbide burs can be used in the posterior and lateral sectors whereas diamond burs can be used in the anterior regions.

• Special kits
  • KaVo O-drive oscillating contra-angle combined with Komet O-Stripper discs

This is a segmented 60° oscillating diamond disc. Its pivot angle is 30°.

It can be fixed in the contra-angle at the desired angulation, which facilitates access to the site and improves visibility and can safely be manipulated without risk of cutting into soft tissue.

The discs have variable thicknesses of .15 mm, .30 mm, and .45 mm. The orthodontists operate from the occlusal to the cervical area of the tooth under a cooling water jet.

• The Orthofile system (SDC)

In this system, we use mini-stripping bands that are mounted on special contra-angles that oscillate from buccal to lingual. Their thickness varies from 15 um to 150 um and the maximal amount of enamel that can be removed per tooth is .3 to .5 mm.

With this system, there is no risk of cutting into soft tissue but patients can feel vibrations.

• Polishing

While polishing helps restore teeth to their original anatomical form and remove roughness from the tooth surfaces, it can also help remove some enamel substance from the interproximal regions. However, it is important to remember not to go beyond a certain limit when polishing.

This can also include stripping by hand using a thin metal strip covered on one or both sides with an abrasive material. Hand stripping can be laborious and ineffective.

While dental stripping is widely practised in orthodontic treatment, we must keep in mind the potential biological consequences on the teeth and the periodontal tissues caused due to this abrasive practice.