By Duncan Y. Brown, BSC, DDS, Calgary, AB, Canada
Thomas R. Pitts, DDS, MSD, pioneered the bracket placement technique known as SAP, or Smile Arc Protection. The technique enhances smile arc aesthetics and addresses proclination concerns common to non-extraction treatment. SAP bracket placement is designed to align the contact points: As the contact point heights progress apically from posterior to anterior in the upper arch, the slot plane follows the same progression. The following are some high points of the technique:
Prebonding “positive and negative” coronoplasty is very important. When done prior to bonding, esthetic recontouring improves the ability to place brackets in the appropriate location to maximize the smile arc, optimize axial inclination, and control first- and second-order changes in tipping mechanics.
Prior to bonding, soften the cusp tips of the cuspids and first bicuspids, normalize facial irregularities, and adjust length/width ratios of the upper anterior teeth. All adjusted surfaces are smoothed with a white stone and black rubber tip in a high-speed handpiece prior to bonding. Recontouring allows the cuspid to be bonded ideally for smile arc and will establish an optimal contact point relationship with the lateral incisor, while the incisal edge of the cuspid falls on the idealized smile arc.
Assess the upper occlusal plane in a natural head position. As a smile arc develops from upper first molar to upper first molar, it is important to assess the occlusal plane of the upper arch in a natural head position. Contrary to straight-wire theory where the bracket slot must be positioned at FA, SAP follows a different approach.
In patients with “flat” occlusal planes, the progression of the wire plane created by bracket position must increase to develop the smile arc by extrusion of the upper incisors relative to the upper bicuspids. In patients with normal occlusal planes, a more modest progression in the wire plane is still advisable to protect the smile arc as the upper arch broadens with treatment. OP
