Comparison between rapid and mixed maxillary expansion through an assessment of dento-skeletal effects on posteroanterior cephalometry

Abstract

BackgroundThe aim of this study is to compare the dento-skeletal effects of rapid maxillary expansion (RME) and mixed maxillary expansion (MME), assessed on posteroanterior (PA) cephalograms.MethodsTreatment groups consisted of 42 patients; mean age in RME group (n = 21,13 female and 8 male subjects) was 8.8 years ± 1.37 at T0 and 9.6 years ± 1.45 at T1 and mean age in MME group (n = 21, 12 female and 9 male patients) was 8.9 years ± 2.34 at T0 and 10.5 years ± 2.08 at T1. Seventeen bilateral anatomic landmarks, 16 linear (12 skeletal and 4 dental) and 4 angular measurements were assessed for each patient at T0 and T1. Data from the two groups were compared using independent sample t test (p < 0.05).ResultsAt T0, the groups were similar for all examined variables (p > 0.05). Significant and equal increase of lateronasal and maxillary and upper and lower molar widths (p < 0. 01) occurred in both groups at T1. Significant but different increases were observed for maxillary incisal, upper left first molar-lateroorbitale, and maxillary first molar angles (p < 0.001 vs. p < 0.05). Significant increases were reported for upper inter-incisal width apex (p < 0.001) and upper right first molar-lateroorbitale angle (p < 0.05) only in the RME group. At T1, differences in maxillary incisal angle (p < 0.05), upper left first molar-lateroorbitale, and maxillary first molar angles (p < 0.001) were noted.ConclusionsRME and MME were both effective to increase skeletal transverse dimensions by opening mid-palatal suture in growing patients, while MME was associated with minor dental side effects than RME.

Comparison between rapid and mixed maxillary expansion through an assessment of arch changes on dental casts

“…However, as previously reported, the expansion obtained with MME presents minor dental side effects [22–24]. We may thus speculate that, although comparable at T1 in both groups, the increase in transverse diameters in the upper arch following MME is due to skeletal basal expansion rather than dental tipping.…”

“…The difference in upper intercanine width is likely a result of the greater anterior opening of the mid-palatal suture, a consequence of increased skeletal expansion obtained by MME, as shown in our previous studies [22–24]. …”

“…A further research comparing the arch changes on dental casts, using the same sample and treatment procedures, confirmed the validity of MME as a useful alternative protocol for improving transverse arch dimensions and correcting posterior crossbite, as well as for gaining arch space to relieve mild-to-moderate tooth-size/arch discrepancies [23]. A third paper compared the dento-skeletal changes on postero–anterior cephalograms in two groups of pre-pubertal patients treated with MME or RME [24, 25]. Both expansion procedures proved effective in increasing skeletal transverse dimensions by opening the mid-palatal suture in growing patients.…”

“…Maxillary expansion can be performed with different methods: rapid maxillary expansion (RME) [15–17], semirapid maxillary expansion (SRME) [18], slow maxillary expansion (SME) [19–21] and mixed maxillary expansion (MME) [22–24]. Each treatment protocol is based on a different rationale, but all produce both skeletal and dental changes.…”

Comparative Study of Maxillary Expansion by Alternate Rapid Maxillary Expansion and Constriction Versus Hyrax Expansion

“…It increased by (3.5°) in RME group and by (3.7°) in Alt-RAMEC group. This result is in agreement with the result of a previous study (26) that stated an increase in Mfma of about 4.15° after RME. In a previous systematic review (27) ,it was stated that at the end of expansion the buccal inclination of the anchored teeth was increased by using a heavy force.…”