Buccal Bone Changes Around First Permanent Molars and Second Primary Molars after Maxillary Expansion with a Low Compliance Ni-Ti Leaf Spring Expander.

Vestibular bone thickness changes and dento-alveolar buccal tipping of second primary molars and of first molars after maxillary expansion performed with a slow maxillary expansion protocol was investigated. Twenty patients (mean age 7.3 ± 0.9 years old; 9 male and 11 female) were treated according to the Leaf Expander protocol. Buccal alveolar bone thickness (BT), buccal alveolar bone height (BH), inter-dental angle (TIP), and inter-molar width (IW) regarding first molars and second primary molars were calculated before and after expansion on cone beam computed tomography (CBCT) images. Descriptive statistics and paired t-tests were used to assess changes between the pre-treatment and post-treatment measurements. Bone thickness vestibular to second primary molars and intermolar width of both teeth were the only variables that showed statistically significant changes. It appears that buccal bone thickness vestibular to first molars was not significantly reduced after maxillary expansion with the Leaf Expander. The clinical use of a slow maxillary expander with Ni-Ti springs appears efficient and safe in in the correction of maxillary hypoplasia during mixed dentition.