Analisi degli effetti della terapia con distalizzazione molare

Objectives

The aim of the present study was to use published data to evaluate quantitavely the skeletal and dental effects of extraoral and intraoral molar-distalizing appliances in individuals with Class II malocclusion.

Materials and methods

We conducted a literature search that identified 37 prospective or retrospective clinical studies that met our predefined inclusion and exclusion criteria. The data reported in these publications (SNA°, SNB°, FMA°, LFH, SN-PP°) were analyzed to identify the skeletal changes (sagittal and vertical) produced by the molar distalization appliances.

Results

Use of extraoral distalizing devices (Kloehn headgear) produced changes in the sagittal plane that consisted in reduced maxillary protrusion (SNA° -1.88°). Instead this value tends to increase (albeit nonsignificantly) in subjects treated with intraoral devices (+0.14°).

Neither the extraoral nor intraoral distalizing appliances had any significant effects on the SNB° angle, which ranged from -0.55° to -0.35°, or on the inclination of the mandibular (FMA°) or palatal (SN-PP°) plane (which were +0.36° and +0.45°, respectively). Anteroinferior facial height (ANS-Me) tended to increase (mean +1.05 mm).

In subjects treated with Kloehn headgear, significant distalization of the molars (3 mm) was associated with secondary distalization of the maxillary premolars and upper incisors, whereas in subjects treated with intraoral appliances, significant loss of anchorage was observed at the levels of the first and second premolars (mean 1.5 mm and 2.17 mm, respectively) and the central incisors (mean 1.43 mm).

Conclusions

Both the extra- and intraoral appliances were efficient in achieving a Class I molar relationship. Use of the Kloehn headgear allowed the maxillary molars to be distalized without altering the flaring of maxillary incisors. Noncompliant intramaxillary appliances (Pendulum, First Class, Distal-Jet And Jones-Jig) produced distalization of the molars that was inevitably associated with loss of anchorage, reflected by mesial movement of the incisor and premolars. This adverse effect of the intraoral appliances and the longer treatment times and high dependence on patient compliance of extraoral distalization should be considered.