Inflammatory responses in two commonly used rat models for experimental tooth movement: comparison with ligature-induced periodontitis.
OBJECTIVE
To compare two often used rat models for experimental tooth movement, namely the elastic band, and the coil spring model. They were compared with a silk-ligature-induced periodontitis model.


METHODS
Thirty six, 6-weeks-old rats were used. In a split mouth design four experimental conditions were allocated by permutation: (1) insertion of an orthodontic elastic band between the maxillary first and the second molar, (2) placement of a silk ligature around the cervix of the upper second molar, (3) a 10cN NiTi coil spring for mesial movement of the three maxillary molars as one block, and (4) Control. After 1, 3, and 5 days, rats were killed and immunohistochemical staining for ED1, cathepsin K, and MMP9 was performed.


RESULTS
A time-dependent increase in the inflammatory infiltration of the interdental papilla was found in the elastic band and the ligature model, but not in the spring model. The disruption of the epithelium of the interdental papilla and the transseptal fibers was less severe in the spring group than in the other two experimental groups. All three experimental groups showed a time-dependent resorption of the interdental bony septum. However, this started faster and was more severe in the elastic band and the ligature than in the spring group. The numbers of cathepsin K+ and MMP9+ cells were higher in the elastic band and the ligature group than in the spring group.


CONCLUSIONS
Elastic bands yield similar periodontal effects as ligatures. The spring model is to be preferred for experimental tooth movement studies.
Xie
Rui
R
Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, 309 Dentistry, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Kuijpers-Jagtman
Anne Marie
AM
Maltha
Jaap C
JC
D000704:Analysis of Variance; D000818:Animals; D001862:Bone Resorption; D004195:Disease Models, Animal; D007124:Immunoenzyme Techniques; D008026:Ligation; D008297:Male; D008963:Molar; D010518:Periodontitis / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000379:methods*