Skeletal Anchorage for Orthopedic Correction of Growing Class III Patients

Bong-Kuen Cha, Peter W. Ngan

Maxillary protraction headgear in conjunction with expansion appliances have been widely used in the treatment of Class III malocclusion with maxillary deficiency. However, there are problems associated with protracting the maxilla with conventional tooth-borne anchorage. These include the loss of dental anchorage, which is of concern, especially in situations in which preservation of arch length is necessary. In addition, tooth borne anchorage alone does not allow the application of orthopedic force directly to the maxillary sutures. The latter effects can be eliminated or minimized by the use of absolute intraoral anchorage devices, such as miniplates. Several reports have been published in the literature on the use of miniplates for maxillary protraction. However, the skeletal and dental changes in response to maxillary protraction using miniplates as anchorage have not been reported. The purpose of the present study was to quantify and compare the effects of maxillary protraction when using a facemask in conjunction with a rapid maxillary expansion appliance (RME) with a second group treated with a facemask together with a surgical miniplate as anchorage.

 Schematic illustration shows a curvilinear-type miniplate fixed with 3 self-tapping miniscrews on the zygomatic buttress area. The end of the miniplate was exposed between the canine and first premolar area, located over the keratinized attached gingiva to prevent gingival irritation. Protraction force is approximately 300∼400 gm per side and the line of force is 30° to the occlusal plane.

Pretreatment records of 11-year, 4-month-old male patient (THC) with Skeletal Class III malocclusion and anterior crossbite, crowding. The concave profile is shown in the lateral photograph. 

Patient (T.H.C.) treated with a face mask with the skeletal anchorage system for 11 months. 

Facial and intraoral photographs of patient T.H.C. after 10.5 months of protraction treatment. After protraction with miniplate, Class III malocclusion has been corrected.

 Superimposition of pre- and posttreatment tracings of cephalometric radiographs of T.H.C. SNA and ANB angle increased 2.1°, 4.0°, respectively attributable to down and forward maxillary movement. Note that there was little dentoalveolar movement.

Pretreatment records of a 10-year, 8-month-old female patient (J.E.C.) with skeletal Class III malocclusion and anterior crossbite. Loss of space for upper right second premolar attributable to mesial movement of right first molar. Showing concave profile in lateral photograph.

Facial and intraoral photographs of J.E.C. during the maxillary protraction with miniplates. Pendulum appliance was used simultaneously to gain space for the right second premolar.

Facial and intraoral photographs of J.E.C. after 9 months maxillary protraction and pendulum appliance. Class III malocclusion has been corrected and right second premolar has erupted successfully.

Superimposition of pretreatment and after maxillary protraction tracings of cephalometric radiographs of J.E.C. SNA and ANB angle increased 1.5°, 2.6°, respectively attributable to down and forward maxillary movement. Maxillary molar moved distally as the result of the pendulum appliance treatment.

Posttreatment facial and intraoral photographs after treatment by multiband system. 

Dental measurements on the coordinate system.

 Sagittal maxillary dentoalveolar changes in miniplate group and RME group. Mesial dentoalveolar movement in upper dentition can be absolutely prevented using surgical mini-plate
18 December 2014 - Category: Adult Orthodontics
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