Zsuzsa Oltyan, Klara Branzaniuc, Nagy Bota Monica Cristina, Mariana Pacurar
Introduction: Mandibular prognothism is a serious dento-maxillary anomaly with multifactorial etiology and complex therapeutic options characterized by insufficient development of the maxilla in the sagittal direction relative to the normal development of the mandible.
Aim of study: The authors have proposed to study the possibilities of mandibular prognothism correction by maxillary expansion using two types of stress breakers, performing measurements on orthodontic pre and posttreatment samples the maxillary transverse distances (IP, IM, palate depth).
Material and method: Our study was performed in a group of 35 patients aged between 12 14 years old (18 young female patients and 17 young male patients) suffering from mandibular prognothism, who previously did not undergo any orthodontic treatment and durimg the treatment wore two different types of stress breakers (the first group wore Huet classical stress breaker and the other group wore Leone spider stress breakers). The jaw width index was calculated (IP, IM, and palate depth) by monitoring the degree of correction of the lateral crossbite and degree of maxillary expansion before treatment, then 6 months, 1 year and 2 years after the treatment was started.
Results and discussions: The application of stress breaker is the technique of opening the midpalatal suture by attaining a transversal expansion. The suture undergoes the intervention in the state of fibrous joint. The patient should activate the appliance by turning the screw once a day (slow expansion). In the first three months after initiating the treatment we attained a 3 mm expansion at the premolar level and 4.5 mm at the molar level by using classical stress breaker and 3.5 respectively 4.5 mm by using spider stress breaker. Subsequent to one year treatment we could observe that the diameters were slightly increased and after two year of fixed treatment we noticed partial receding (loss of 1mm at the premolar level) in both group of patients.
Conclusions: Intermaxillary disjunction is an effective method in mandibular prognothism provided that the patient is discovered at the beginning of dentition, when sutures are active (12 -14 years in young females and 14-16 years in young males). The two types of stress breakers work similarly, but correction is faster in case of a spider stress breaker, because of a stronger screw positioned posteriorly.