Rapid palatal expander: Maxillary and mandibular measurements using manual and digital methods

OBJECTIVES To evaluate the existence of a cor-relation between rapid palatal expansion and changes in width, length and perimeter of the upper arch, as well as changes in width, length and perimeter of the lower arch, as a natural consequence of those of the maxillary complex over time. MATERIALS AND METHODS This study was conducted on a sample of 19 patients treated with RPE, rapid palatal expansion. The entire group was divided in two samples: in the first sample data were recorded before the start of treatment for rapid palatal expansion and at 6 months follow-up from the end of the activation period; in the second group information was acquired at the start and at 3 month follow-up. Each patient was treated with an orthodontic-ortho-pedic expansion device Hyrax type, with a central screw, with an activa-tion protocol of a quarter turn of the screw performed two times a day for the first three days and once a day until the control appointment. After the control appointment it has been prescribed to proceed with the daily activations of a quarter turn personalized for every single patient, until the planned expansion is reached. The data were examined with two different methods, then a comparison between them was made: the measurements were taken manually, directly on the cast models, with a caliber and then with digitally using intraoral scanner GC Aadva IOS (GC Europe N.V., Leu-ven, Belgium). For each group the following data were recorded at time zero and at the post-expan-sion follow-up time at maxillary and mandibular level: inter-canine width, inter-joint width, inter-mo-lar width, antero-posterior length, perimeter of the arch. Finally, the correlation index be-tween transverse expansion of the palate and variation of the arch perimeter following ortho-dontic-orthopedic therapy is evaluated. RESULTS AND CONCLUSIONS Manual and digital acquisitions showed comparable results. The data show that there are no statistically significant differences between the two groups at time zero, for both arches. The results show a greater variation for all the variables examined in favor of the group with a six month follow-up, due to the greater possibility of growth of the jaw, directly proportional to the greater period of time elapsed between evaluations; by the statistical point of view, however, there are values that are not significantly different as inter-canine, inter-premolar and arch pe-rimeter parameters, opposed to inter-molar and antero-posterior data that are statistically signifi-cant. CLINICAL SIGNIFICANCE The examination of two groups with different follow-up showed non-homogeneous variations for all the dental elements, in particular at molar level a longer period of time is necessary for the achievement of an optimal expansion. The results of this study can be exploited by the clinician to correct unilateral or bilateral posterior cross bites, dental crowding, especially in patients with unfavorable tooth-arch relationships, thus allowing alignment, restoring correct occlu-sal shape and function, correcting asymmetries, as well as planning an orthodontic treatment.