Comparison of the effectiveness of skeletal and tooth-borne protraction methods with or without alternate rapid maxillary expansion and constriction protocol in patients with Class III malocclusion.

Background: This study aimed to compare the efficiency of maxillary protraction achieved through facemask treatment with either a hybrid-hyrax (HH) or an acrylic cap splint (ACS) appliance when used in conjunction with alternate rapid maxillary expansion and constriction (Alt-RAMEC) or conventional rapid maxillary expansion (RME) protocols.

Methods: This study analyzed a total of 60 patients in 4 groups of 15 patients each and treated with HH-Alt-RAMEC protocol (HH-Alt, aged 10.38 ± 1.19 years), ACS-Alt protocol (aged 10.43 ± 0.99 years), HH-RME protocol (aged 9.74 ± 1.05 years) and ACS-RME protocol (aged 10.70 ± 0.98 years). Lateral cephalograms were taken before and after the facemask were compared. A 1-way analysis of variance with a Tukey honest significant difference post-hoc test was used for intergroup comparisons, whereas a paired sample t test was employed for intragroup comparisons.

Results: Correction of Class III skeletal malocclusion was achieved in all groups. HH-Alt showed significantly more maxillary protraction with an increase in AVRP of 4.02 mm compared with 2.65 mm in ACS-Alt and 2.3 mm in ACS-RME (P <0.001). HH-RME also showed a significantly more maxillary protraction in AVRP of 3.58 mm compared with 2.3 mm in ACS-RME (P <0.001). The rate of protraction was higher in HH-Alt (0.61 ± 0.16) and HH-RME (0.56 ± 0.29) than in ACS-RME (0.31 ± 0.12). The maxilla showed significantly more rotation in ACS-Alt (-1.66° ± 1.13°) and ACS-RME (-1.97 ± 1.75°) than in HH-Alt (-0.49° ± 1.18°) and HH-RME (-0.35° ± 1.86°), whereas the mandible showed significantly more clockwise rotation in ACS-RME (2.08 ± 1.71) than in HH-Alt (0.80 ± 0.94) and HH-RME (0.63 ± 1.82). The maxillary skeletal effect in the overjet correction was greater in HH-Alt (71.0%).

Conclusions: All treatment options achieved maxillary protraction. In the short term, hybrid groups (HH-Alt and HH-RME) provide more effective maxillary skeletal protraction than ACS-RME and demonstrate superior control in the vertical dimension than in tooth-borne groups. The Alt-RAMEC protocol improved the amount of maxillary protraction of the tooth-borne appliance group. The choice of anchorage of the appliance (skeletal or tooth-borne) is found to be more critical than the expansion method (RME or Alt-RAMEC).