MATERIALS AND METHODS: Sixteen New Zealand white rabbits were randomly divided into four groups. Modified Hyrax expanders were placed across the midsagittal sutures and secured with miniscrew implants with the following activations: group 1 (control), 0.5 mm expansion/day for 12 days; group 2, 1 mm instant expansion followed by 0.5 mm expansion/day for 10 days; group 3, 2.5 mm instant expansion followed by 0.5 mm expansion/day for 7 days; and group 4, 4 mm instant expansion followed by 0.5 mm expansion/day for 4 days. After 6 weeks, sutural expansion and new bone formation were evaluated histomorphometrically. Statistical analysis was performed using Kruskal-Wallis/Mann-Whitney U tests and Spearman's rho correlation (p
METHODS: Sixteen New Zealand white rabbits, 20 to 24 weeks old, were randomly divided into 4 experimental groups. Modified hyrax expanders were placed across their interfrontal sutures and secured with miniscrew implants located bilaterally in the frontal bone. The hyrax appliances were activated as follows: group 1 (control), 0.5-mm per day expansion for 12 days; group 2, 1-mm instant expansion followed by 0.5 mm per day for 10 days; group 3, 2.5-mm instant expansion followed by 0.5 mm per day for 7 days, and group 4, 4-mm instant expansion followed by 0.5 mm per day for 4 days. After 6 weeks of retention, sutural separation and sutural bone modeling were assessed by microcomputed tomography and quantified. Statistical analysis was performed using Kruskal Wallis and Mann-Whitney U tests and the Spearman rho correlation (P <0.05).
RESULTS: Median amounts of sutural separation ranged from 2.84 to 4.41 mm for groups 1 and 4, respectively. Median bone volume fraction ranged from 59.96% to 69.15% for groups 4 and 3, respectively. A significant correlation (r = 0.970; P <0.01) was observed between the amounts of instant expansion and sutural separation.
CONCLUSIONS: Pending histologic verifications, our findings suggest that the protocol involving 2.5 mm of instant expansion followed by 0.5 mm per day for 7 days is optimal for accelerated sutural expansion. When 4 mm of instant expansion was used, the sutural bone volume fraction was decreased.
MATERIALS AND METHODS: An electronic search of the scientific literature from January 2005 to June 2016 was done using Web of Science, Dentistry & Oral Sciences Source and PubMed databases. A combination of search terms "rapid maxillary expansion", "nasal", "airway" and "breathing" were used. Studies that involved surgical or combined RME-surgical treatments and patients with craniofacial anomalies were excluded.
RESULTS: The initial screening yielded a total of 183 articles. After evaluation of the titles, abstracts and accessing the full text, a total of 20 articles fulfilled both inclusion/exclusion criteria and possessed adequate evidence to be incorporated into this review.
CONCLUSIONS: Non-surgical RME was found to improve breathing, increase nasal cavity geometry and decrease nasal airway resistance in children and adolescents.
MATERIALS AND METHODS: Sixteen male New Zealand white rabbits (20 to 24 weeks old) were randomly divided into 4 experimental groups (n = 4): group 1, conventional rapid sutural expansion; group 2, accelerated sutural expansion; group 3, accelerated sutural expansion with continuous ostectomy; and group 4, accelerated sutural expansion with discontinuous ostectomy. All sutural ostectomies were performed using a piezoelectric instrument (Woodpecker DTE, DS-II, Guangxi, China) before expander application with the rabbits under anesthesia. Modified hyrax expanders were placed across the midsagittal sutures of the rabbits and secured with miniscrew implants located bilaterally in the frontal bone. The hyrax expanders were activated 0.5 mm/day for 12 days (group 1) or with a 2.5-mm initial expansion, followed by 0.5 mm/day for 7 days (groups 2 to 4). After 6 weeks of retention, the bone volume fraction, sutural separation, and new bone formation were evaluated using micro-computed tomography and histomorphometry. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests and Spearman's rho correlation (P