[Correlation between the lower first permanent molar axis and the premature loss of temporary molars]

The aim of our study was to determine the impact of premature loss of temporary molars upon the longitudinal axis of the first permanent molar.

The study sample was formed by 94 orthopanthomografies of child patients with premature loss of lower temporary molars (first or second) after clinical eruption of the first permanent molar. All panoramic radiographs have been realized with the same panoramic unit with 1.4% magnification coefficient and were analyzed using a standardized technique of tracing the images of teeth and bone on matte acetate paper. It was evaluated the angle between longitudinal axis of first permanent lower molar and occlusal plane.

It was observed that premature loss of lower second deciduous molar modifies greater the vertical axis of first permanent molar (between 61 degrees and 79 degrees) then premature loss of first lower primary molar. This is perhaps because the loss of space in the case of premature exfoliation of first primary molar is due more to distal drift of canine then mesial drift of molars.

The drift to mesial of first permanent molar is more accentuated proportional with the age at which appeared premature loss and so it is loss of leeway space.