Unilateral Upper Molar Distalization In A Severe Case Of Class II Malocclusion. Case Presentation

This presentation is uppon pacient C.C., female, age 9 years and 5 month, from Hârlău, Iași; initial appointment was în 2009 for esthetic imbalance. The chief complain of the pacient was the protrusion of anterior maxillary teeth. The diagnosis was skeletal class II, dental class II/1 Angle malocclusion, with crowding and no space for the eruption of second premolar due to the premature loss of decidous teeth, severe proclination of lower incisors, midline shift and increased overjet and overbite. For this severe case we used a class II mechanics based on the increasing upper arch lenght in the posterior region, using upper molar distalization combined in a second phase of treatment with four premolar extraction

THE ETIOLOGICAL FACTORS INVOLVED IN DENTAL ARCH PERIMETER SHORTENING

The main purpose of the study was to highlight the causes that may lead to reduction of arches: early loss of deciduous teeth, with consecutive dental drifting on the arch, followed by narrowing of the space necessary for the eruption of successional teeth, caries of the deciduous teeth or ectopic eruption of the first permanent molars. The mesial position of M1 had a frequency of 19.31% of the total number of analysed cases; maximum frequencies have been registered for the localization on the lower arch; M1 ectopia has rarely occurred on the studied batch; the frequency of lateral group mesial position was of 10.34% on the studied batch, registering maximum values for the localisation on the upper arch. The early loss of deciduous teeth was identified in almost 30% of the analysed cases, while the reduction of the space necessary for the eruption of successional teeth was registered in almost 39% of cases, space narrowing resulting both from the caries of deciduous teeth and from their early loss

STRESS DISTRIBUTION AS A FUNCTION OF THE POINT OF FORCE APPLICATION ON THE UPPER FIRST PERMANENT MOLAR DURING DISTALIZATION

Starting from the premise that the tooth is a structure that may be deformed under stress, the study followed the distribution of stresses at the level of the upper first permanent molar, when using some distalization forces with palatinal, respectively vestibular application point, and evaluated the size and type of dental shifts. The investigation alsoevaluated the efficiency of the various devices of molar distalization, by means of a mathematical pattern and by applying a force with a constantpalatinal magnitude 3N and, subsequently, vestibularly, at the level of the upper first permanent M1, for simulating a real clinical situation. The study applies the method of finite elements for demonstrating the existence of molar tipping, as well as for analyzing the level of coronary/radicular stresses as a function of the application point of the distalization force. The mathematical pattern used in the study, created with SolidWorks2006 and COSMOS X PRESS programs, showed that, when thedistalization force is applied vestibularly, a larger coronary shifting, comparatively with a palatinally-applied distalization force, is observed