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Anterior Crowding in Adult Patients

Problem

“On adult cases with minor crowding in the upper anteriors, I often strip the interproximal surfaces for space to allow improvement of the esthetics. Occasionally, this approach does not provide the space needed. What appliance do doctors prescribe most in these situations?”

Solution

When calculations indicate a deficiency in the space available through stripping, a review of the arch form may provide the key to alternate approaches. Often these cases display a pronounced collapse of the arch width anteriorly, resulting in a “V” shaped arch form. An arch width analysis shows a considerable deficiency in the first premolar and cuspid widths. By “fanning” the intercanine area, the arch length can often be increased to provide the necessary space for improvement without effecting the posterior occlusion.

When presented with minor crowding and a “V” arch form in the adult dentition, many doctors prescribe an upper Removable Expansion Appliance with a Hinge-Gear. When activated, the gear opens the appliance in the anterior while the hinge, which is placed at the distal-most portion of the acrylic, holds the posterior closed.

The patient is instructed to activate the appliance once each week. An arrow imbedded in the appliance indicates to the patient the direction in which the gear should be adjusted. Each adjustment provides one-quarter millimeter of activation. At each visit, the adjustment loops on the labial bow should be opened slightly to keep pace with the expansion.

The labial bow serves as a fulcrum for rotations and as a guide for final alignment as the anteriors are moved by the acrylic on the lingual. However, finger springs are often included to assist in improving rotations. As the case progresses, slight stripping may be considered to finish the case and flatten the contact points for long-term stability.

Expansion on adult cases often requires and indefinite retainer schedule. After active treatment, a retainer is usually worn for at least nine months and is re-inserted approximately once each month thereafter as a “check guide” against relapse. If it is difficult to seat, indefinite nighttime retainer wear is usually indicated.

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