Interproximal Enamel Reduction (Stripping)
Space creation is an important part of orthodontic treatment. Interproximal enamel reduction is a long-established alternative treatment to extraction. A number of terms are used in the orthodontic literature to describe this technique, and this can sometimes be confusing: interproximal reduction (IPR) of enamel, stripping, tooth size reduction, recontouring, reshaping, slenderizing, slicing, and trimming of teeth are all used to describe this technique.
Contemporary orthodontics has moved away from the very clearly defined extraction and nonextraction approaches that were predominant for many years. Symmetrical extraction of two premolars, which creates between 14 and 16 mm of space, often leaves the balance heavily lopsided towards space creation. This can in turn lead to prolonged residual space closure, retroclination of incisors, and sometimes the creation of a tooth-sized discrepancy, leading to small extraction spaces remaining at the end of fixed-appliance treatment. However, interproximal enamel reduction can deal with a number of space requirements in a predictable way.
Advantages and Disadvantages
Interproximal enamel reduction has several advantages:
There is only minimal loss of tooth substance (in comparison with extraction treatment in particular)
Less overall tooth movement is often necessary (in comparison with space closure in an extraction approach).
Treatment times are usually shorter.
There is potentially better stability of the arches (due to establishment of contact surfaces rather than contact points).
Residual extraction spaces after orthodontic treatment are avoided.
Although some of the potential side effects are not confirmed in the scientific literature, it is important to carefully inform patients and obtain their consent, in view of the following potential issues associated with tooth size reduction:
Interproximal cleaning can be more difficult following the procedure and special adjuncts may become necessary in order to maintain good oral hygiene.
There may be cosmetic issues such as a squarer appearance of the teeth.
There is a potential for all the enamel to be removed down to the dentine, with subsequently increased sensitivity of the teeth.
There is potentially an increased risk of decay (caries).
It is advisable to document the patient consultation, with special emphasis on the discussion of IPR.
Indications and Amount of Space Creation
IPR is particularly useful in patients with primary or secondary crowding. It is also used in patients with significant tooth size discrepancies between the arches and those with abnormally shaped teeth and to reduce or eliminate triangular-shaped spaces in the gingival tissues in patients with an increased distance from the dental contact point to the alveolar crest. The overall space that is made available has been extensively described in the literature, but with significant variations between authors. Most references suggest removing no more than 50%of the existingenamel thickness. This will lead to space creation between 6.5 and 9 mm per arch.5 , 6 , 10 , 23 , 24 Up to 11 mm of space may be created if all of the teeth including the second molars are slenderized.26 Table 8.5 gives an indication of the values for amounts of enamel that can be reduced for each individual tooth. The lower incisors should only be slenderized by approximately 0.2mm on each side, so that no more than 50% of the enamel is reduced.8 , 11 , 25