Surgically assisted maxillary expansion; about a clinical case.

INTRODUCTION: By means of orthopedics, orthognathic surgery or orthodontics, the management of the maxillary transverse defisciency is a key element of the orthodontic treatment plan, and the guarantee of its stability. the following work aims to support, through a clinical case, the management and the progression of the treatment of the maxillary transverse deficiency associated to a class III skeletal anomaly. OBSERVATION: The authors report the case of a 15-year-old patient with a severe class III    malocclusion, with severe maxillary transverse deficiency. The objectives of the treatment were, first, to solve the transverse disharmony by surgically assisted rapid maxillary expansion (SARME), then, secondly, to remove the dentoalveolar compensations and a bimaxillary orthognathic surgery, was carried out to correct the sagittal and vertical disharmony. CONCLUSION: Surgically assisted rapid maxillary expansion (SARME) appears to be advantageous, both functionally and aesthetically to overcome transverse maxillary deficiency. The agreement between the orthodontist, the maxillofacial surgeon and / or the plastic surgeon, both in the schedule and in the choice of surgical interventions, remains decisive concerning ortho-surgical treatments.

Relationship between electrochemical corrosion and the tribologic properties of orthodontic alloys.

The aim of this study was to investigate the electrochemical properties of orthodontic alloys (SS, CuNiTi and TMA) and the impact of corrosion on their friction coefficient. Twelve pairs of 5-cm long 017×.025 rectangular wires (SS/SS, CuNiTi/SS, TMA/SS) were formed and SEM observations and friction tests were conducted on the surface of each pair of wires. Then, each type of alloy was dipped in artificial saliva during different immersion times (24h, 48h, 72h and 1week). Following the electrochemical tests, the samples were recovered for a second series of SEM observations and a second friction test. After 24h of immersion, we observed corrosive attacks on the surface of the alloys and a reduction of the friction coefficients. After 1week, we observed surface passivation and an increased friction coefficient which attained values identical to those prior to immersion. One can conclude that, at the onset of corrosion, the friction coefficient decreases but that this advantage diminishes after passivation of the alloy surfaces.