title: Longitudinal quantitative evaluation of the mid-palatal suture after rapid expansion using in vivo micro-CT.
abstract: New bone formation is known to occur between the opened palatal bones after rapid mid-palatal expansion (RME), although the time-dependent changes in the mid-palatal suture after RME have not been fully examined. Thus, we investigated time-dependent morphological changes in the mid-palatal suture using in vivo micro-computed tomography (mCT) and the expression of bone morphogenetic factors. RME was performed by inserting a 1.5-mm-thick circular metal ring between the maxillary incisors of rats, and morphological changes in the mid-palatal suture were investigated using in vivo mCT imaging after RME. Bone morphogenetic protein 2 (BMP-2) and insulin-like growth factor-I (IGF-I) expression in the suture were also examined using reverse-transcription polymerase chain reaction and immunohistochemistry. The bone volume of the mid-palatal suture decreased after RME to a minimum of -0.34mm(3) on day 12, then increased with bone formation over time and reached -0.13mm(3) on day 24. Significant increases in BMP-2 and IGF-I mRNA expression after RME were found on day 3 compared with day 0. By immunohistochemistry, BMP-2 and IGF-I were detected in osteoblasts on days 5 and 7, in endothelial cells of blood vessels, and fibroblasts on day 7. Expansion of the mid-palatal suture continues for 12 days after a single RME, and restoration requires more than 30 days. Additionally, BMP-2 and IGF-I may play important roles in the restoration process.
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takenouchi
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; Division of Clinical Research, Dental Research Center, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Kotoe
authors.initials: K
authors.lastname: Mayahara
authors.affiliation: Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Arai
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Karasawa
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; Division of Clinical Research, Dental Research Center, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. Electronic address: shimizu.noriyoshi@nihon-u.ac.jp.
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D003393:Cranial Sutures / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional; D007124:Immunoenzyme Techniques; D008297:Male; D023421:Models, Animal; D010155:Palatal Expansion Technique; D021362:Palate, Hard / Q000000981:diagnostic imaging*; D012313:RNA / Q000032:analysis; D011857:Radiographic Image Interpretation, Computer-Assisted; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D055114:X-Ray Microtomography
chemical_list: D012313:RNA
keywords: BMP-2; IGF-I; Micro-CT; Mid-palatal suture; Rapid expansion