Methods of gaining space in Orthodontics - with MNEMONICS

One of the most common challenges in orthodontic treatment planning is resolving arch length-tooth material discrepancies. Whether we are managing crowding, reducing overjet, or correcting a curve of Spee, creating space within the dental arch is paramount. Today, we will systematically review the seven fundamental methods of gaining space using the mnemonic PEEPDUDe. Let’s break down the science and clinical application behind each letter.

P stands for Proximal Stripping. Also known as Interproximal Reduction, or IPR. This involves the meticulous removal of enamel from the interproximal surfaces. It is highly effective for mild to moderate crowding and helps stabilize the lower anterior segment by flattening the contact points.

E is for Expansion. This increases the arch perimeter by altering the transverse dimension. We can utilize skeletal expansion, like Rapid Maxillary Expansion, or standard dentoalveolar expansion. A general rule is that 1 millimeter of posterior expansion yields roughly 0.7 millimeters of arch perimeter space.

The second E is for Extraction. This is the most definitive method for resolving severe crowding or bimaxillary protrusion. The choice of teeth—often first or second premolars—depends heavily on anchorage requirements and the patient's soft tissue profile.

The second P is for Proclination of Anteriors, which means tipping the incisors labially. Biomechanically, for every 1 millimeter of anterior proclination, we gain approximately 2 millimeters of arch space. However, this is strictly limited by the symphyseal bone thickness and the patient's periodontal phenotype.

D stands for Distalization, which is moving the buccal segments posteriorly. Traditionally achieved with headgear, we now frequently rely on Temporary Anchorage Devices or intraoral appliances like the Pendulum to achieve bodily movement of the molars distally, preserving our anterior anchorage.

U is for Uprighting of Molars. Molars that have tipped mesially—often due to premature loss of primary teeth or early extraction of adjacent permanent teeth—encroach on the available arch length. Uprighting these molars distally not only regains lost space but also improves the periodontal architecture on the mesial aspect of the root.

Finally, De is for Derotation of Molars. Maxillary molars, due to their rhomboidal shape, occupy a greater mesiodistal space when rotated mesiopalatally. Simply applying a derotational couple to correct the molar's position can free up 1 to 2 millimeters of valuable arch length per side.

To summarize, your orthodontic space management strategy relies on PEEPDUDe: Proximal stripping, Expansion, Extraction, Proclination, Distalization, Uprighting, and Derotation. Careful cephalometric and model analysis will dictate which combination of these biomechanical strategies is appropriate for your patient.