Interproximal reduction in orthodontics: why, where, how much to remove?

Abstract

Interproximal reduction (IPR) is the deliberate removal of part of the dental enamel from the interproximal contact areas, which decreases the mesiodistal width of a tooth. This enamel may be removed for various reasons, but most commonly to create space during orthodontic treatment or to correct tooth-size discrepancies. Several authors have also encouraged its use as a method by which post-orthodontic stability might be enhanced, particularly in the lower anterior region. With the increased use of removable aligners for orthodontic treatment in which non-extraction therapy is often advocated, the use of IPR becomes a valuable tool to relieve crowding without over-expanding the dental arches. It is possible that inaccurate IPR could result in the over-reduction of enamel, the creation of ledges and notches in the proximal surfaces, increased tooth sensitivity or damage to the surrounding soft tissues. However, carefully conducted IPR performed within the recommended guidelines may be used as a safe method to gain space for the relief of crowding, to correct tooth-size discrepancies and to improve aesthetics and long-term stability in selected orthodontic patients.

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

“…The precise quantification of approximal enamel suitable for removal through IPR proves challenging due to the inherent variability in enamel width among both individuals and studies [11]. Moreover, the range of enamel thickness deemed as "safe" for removal has been observed to expand progressively over time [12]. It appears that the enamel is about 0.1 mm thicker on the distal side of the tooth [11], and there is no proven correlation between enamel thickness and tooth size [6].…”

“…After removing the desired amount of enamel and obtaining the necessary space, the enamel needs to be finished and polished by finishing strip and polishing file [8][9][10][11][12][13][14][15][16]. There is considerable variation in the reported levels of enamel roughness after IPR with or without polishing [39].…”

“…Subsequently, application of fluoride gel is recommended to encourage remineralization [8][9][10][11][12][13][14][15][16]. Alessandri Bonetti et al proved in vitro that the utilization of a toothpaste containing zinc-carbonate hydroxyapatite appears to be another effective method for safeguarding stripped enamel surfaces from demineralization [42].…”

Effects of interproximal enamel reduction techniques used for orthodontics: A systematic review

“…The maximum amount of proximal enamel that can be stripped is 50% of this tissue. However, it has been recommended to remove only a third of the enamel thickness, mainly from the interproximal enamel of the molars and premolars 4 . This occurs because the thickness of the interproximal enamel in the anterior teeth is considerably less compared with that of the enamel of the posterior teeth 1 .…”

“…However, it has been recommended to remove only a third of the enamel thickness, mainly from the interproximal enamel of the molars and premolars. 4 This occurs because the thickness of the interproximal enamel in the anterior teeth is considerably less compared with that of the enamel of the posterior teeth. 1 IPR can be performed by manual or mechanical methods using manual abrasive strips, mechanical oscillating abrasive strips, diamond-coated segmented discs or rotating diamond burs.…”