Factores pronósticos del crecimiento espontáneo y del resultado del tratamiento con mentonera en Clases III

Resum

The aim of this study was to identify cephalometric predictive variables for the growth and for the results of early chincap treatment of class III malocclusion in the deciduous-mixed dentition. Two class III samples were studied: a group of 31 non-treated cases (mean age: 7.21±1.67 years) with a period of observation of 2.06 ± 0.96 years, and a group of 42 patients (mean age: 7.11±1.32 years) treated with a chincap as the only appliance for a period of 2.31 ± 1.04 years. Those patients were chosen among 110 because they presented a narrowing of the symphysis as sure sign of compliance. The two samples were divided into two subgroups according to a Cluster analysis, in the basis of the changes of the Wits appraisal: bad or worse growing cases, and excellent or poor results after chincap therapy. Discriminant analysis was applied between subgroups at the time of the first observation to identify cephalometric predictive variables. Discriminant analysis selected 3 predictive variables for the spontaneous growth in the non-treated group: Wits appraisal, lower incisor inclination and ANS-PNS distance. In the chincap treated group, 4 predictive variables were identified to predict excellent or poor results with chincap therapy: Wits appraisal, lower incisor inclination, incisor overjet and cranial deflection. The important role of lower incisor inclination in Class 111 prognosis was emphasized.