Removable Sagittal appliances are frequently prescribed for patients requiring development of the premaxilla and/or distal movement of posterior segments. Many of these patients exhibit buccally displaced cuspids, usually due to a lack of arch length. Most Doctors suggest adjusting the gears one-quarter turn each four days. The patient is instructed to wear the appliance twenty-four hours a day, including at meal time. Wearing during meals is often recommended to take advantage of the forces of mastication on the occlusal bite planes usually included in these appliances. Although models can frequently be marked or occluded to determine the patient’s dental occlusion, a bite registration is recommended for appliance construction. This avoids the necessity of most in-office occlusal adjustments to the appliance.
The Sagittal to advance the premaxilla includes four clasps, two Sagittal gears, occlusal acrylic bite plane, cuspid retractors and/or labial bow. With the models articulated to the Doctor’s construction bite, the lower posterior cusps are deeply imbedded into the acrylic occlusal coverage of the upper appliance. The posteriors are thus anchored and provide the stability necessary for the appliance forces to be directed toward premaxilliary development.
Sagittal for Anterior development
capabilities can be included into the appliance. A midline expansion gear is placed in the appliance with the usual sectioning of the acrylic. Most Doctors find that alternating the Sagittal gear and transverse gear adjustments maintains appliance fit and function. Periodic reduction of palatal acrylic is usually recommended to relieve appliance impingement on soft tissue as the case develops. A second midline screw can be included if survey indicates.
Sagittal appliance for distal
movement of one or both posterior segments is similar to the Sagittal to advance the premaxilla. The anchorage units are altered to maximize anterior anchorage and remove anchorage posteriorly. The posterior acrylic coverage is polished flat while the lower cuspids are indexed into the anterior section of acrylic. Individual color coding of arrows allows the patient to follow the sequence of adjustments when the gears are adjusted alternately, left then right each four days.
Lower Sagittal appliances
are also prescribed for anterior/posterior arch length discrepancies in the mandibular arch. If occlusal coverage is already included on an upper appliance, it will not be included on the lower Sagittal. Otherwise, the occlusal will be covered to once again take advantage of masticatory forces. As with the transverse development appliances, the appliance may be returned periodically for update to the current condition of the case and adjustment of the expansion gears. A new model is required.