title: The effects of force magnitude on a sutural model: a quantitative approach.
abstract: In an effort to quantify the biologic effects of an orthodontic tensile force, the rat interpremaxillary suture was investigated as a model for the periodontal ligament and expanded in vivo with a helical spring across the maxillary incisors. Three levels of force were used: light (50 to 75 g), medium (150 to 175 g), and heavy (250 to 300 g). Thymidine labeling and histologic studies after 12 hours and 1, 2, and 4 days of force delivery are described (n = 48 rats), as are biochemical studies after 2 and 4 days including a 6-hour organ culture (n = 32). The percentage of labeled cells increased significantly in all force groups at 1 day, followed by a rapid decline at 2 days, to a value at 4 days not significantly different from the controls. Biochemical studies showed significant increases in proline incorporation and alkaline phosphatase activity after 2 days of heavy force application. Histologic examinations showed obvious tissue changes beginning by day 1 and involving increases in suture width, vascularity, size and number of cells, amount of osteoid production, and changes in suture morphology. The experimental system was convenient, inflammation-free, and appeared to be reliable as evidenced by characteristic, synchronous tissue and autoradiographic changes in all experimental sutures through 4 days.
authors.affiliation: Department of Orthodontics, University of Tennessee, Memphis.
authors.forename: K A
authors.initials: KA
authors.lastname: Southard
authors.forename: D P
authors.initials: DP
authors.lastname: Forbes
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D003393:Cranial Sutures / Q000033:anatomy & histology* / Q000378:metabolism; D005260:Female; D007180:Incisor; D008437:Maxilla / Q000033:anatomy & histology* / Q000378:metabolism; D009967:Orthodontic Appliances; D010513:Periodontal Ligament / Q000033:anatomy & histology* / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012886:Skull / Q000033:anatomy & histology*; D013936:Thymidine / Q000378:metabolism; D014087:Tooth Movement Techniques; D014316:Tritium
chemical_list: D014316:Tritium; D011392:Proline; D000469:Alkaline Phosphatase; D013936:Thymidine