Effects of functional jaw orthopedics with maxillary expansion on palatal morphology, mandibular growth, airway dimensions, and oral function in Class II malocclusion: A randomized controlled trial

Abstract

Objective The skeletal pattern of a Class II malocclusion can increase the probability of problems with oronasal function. This study aimed to analyze the relationship between the clinical effects of dentofacial orthopedics and oral function in deficient mandibles with proclined maxillary incisors during puberty. Methods Of 120 randomized participants, 63 with complete records were included in the final analysis (median age 12 years; 38% females). Subjects were treated with the Sander bite jumping appliance (BJA; n = 34) or the twin block appliance (TB; n = 29) with a maxillary expansion jackscrew. The growth effect was monitored by comparisons with the findings in 63 historical untreated Class II cases. Palatal scans and cephalograms were analyzed before and at one-year intervals after treatment. Both the children and their parents reported oral symptoms and functional limitations (FLs). Results Palatal volume increased in both appliance groups (BJA 860.3 mm3 [95% confidence interval (CI) 481.6–1,150.1] and TB 958.9 mm3 [95% CI 555.1–1,446.3]) in comparison with the untreated group (287.0 mm3 [95% CI 193.4–426.5]; P < 0.001). However, the treatment did not affect airways. In comparison with the untreated group, the treated groups showed greater mandibular length and reduced overjet (P ≤ 0.002). No linear correlations were found between changes in dentofacial, palatal, or airway characteristics and changes in oral function. However, the palatal volume of the treated children who experienced improvement in FLs increased more than that of those who showed no FL improvement (1,220.6 mm3 [95% CI 772.6–1,616.4] and 760.5 mm3 [95% CI 491.6–1,002.1]; P = 0.035). Conclusions Both appliances promoted mandibular growth and increased oral space, but did not significantly influence the measured upper airway widths.