Rapid Palatal Expansion in the absence of posterior cross-bite to intercept maxillary incisor crowding in the mixed dentition: a CBCT evaluation of spontaneous changes of untouched permanent molars

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ABSTRACT

Aim

The aim of this study was to investigate the reaction of untouched permanent molars following RPE, anchored on
deciduous teeth in the early mixed dentition, aimed to solve maxillary anterior crowding in the absence of posterior cross-bite.

Methods

A prospective clinical trial comprised 35 consecutive patients (20 males and 15 females) treated by the same orthodontist
(MR). All patients showed crowding of the upper permanent incisors in the early mixed dentition in the absence of posterior cross-bite.
RPE was anchored on second deciduous molars and on the deciduous canines. CBCT was taken before and after the removal of the
RPE appliance. The transverse linear changes in width and the variation in the torque of the permanent molars were measured in the
coronal plane.

Results

Relief of incisor crowding was found in all patients. The transverse width between permanent molars
increased significantly. The apices of the upper permanent molars spontaneously expanded more than the crowns, while the opposite
happened on the lower permanent molars. Moreover, the untouched upper permanent molars spontaneously uprighted palatally, while
the lower permanent molars spontaneously uprighted buccally. The variation in the torque of the permanent molars mirrored transverse
normal growth. CONCLUSIONS: In the early mixed dentition and in the absence of posterior cross-bite, it is possible to expand
transversally the palate while uprighting the upper permanent molars in the opposite direction. RPE anchored on the deciduous teeth in
the early mixed dentition, in the absence of posterior cross-bite, provides an "anticipation of transverse growth" and could be indicated
to expand the anterior portion of the maxillary arch perimeter to solve upper incisor crowding.

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