טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentHazan-Molina Hagai
SubjectThe Influence of Extraorporeal Shock Waves Therapy on
Inflammatory Mediators: The Orthodontic Tooth
Movement Model for Sterile
Inflammation
DepartmentDepartment of Medicine
Supervisors Clinical Professor Dror Aizenbud
Professor Abraham Reznick
Full Thesis textFull thesis text - English Version


Abstract

Shock wave therapy is used in medicine due to its ability to stimulate healing processes. Orthodontic force (OF) application evokes an inflammatory reaction resulting in orthodontic tooth movement. The aim of this thesis was to investigate the effect of extra corporeal shock wave therapy (ESWT) on orthodontic tooth movement in a rat model.

In conjunction with orthodontic force commencement, rats were treated by ESWT. The expressions and concentrations of several inflammatory cytokines were evaluated during the first 3 days. In addition, after 3 weeks, the amount of tooth movement was measured along with different microarchitectural parameters by microcomputed tomography.

Furthermore, a compressive force of several magnitudes was applied to human periodontal ligament (PDL) cells along with ESWT. Relative wound density and the expression of mRNA RANKL were evaluated. 

The concentration of all cytokines in the gingival crevicular fluid peaked on the first day and declined thereafter in both the shockwave treated and non-treated groups. In all cases the different cytokines concentrations in the shockwave treated group were smaller compared to the non-treated, however a statistical significant differences was found only in regard to sRANKL.

The percentage of cells expressing all inflammatory cytokines during the study's first two days was reduced in a statistically significant manner in the shock wave treated group compared to the non-treated group. On the first day, the percentage of cells expressing IL-1β and RANKL in the pressure side peaked in both groups, with a sequential rise in TRAP positive cells' number.

After 3 weeks, the addition of ESWT to the OF further stimulated tooth movement by 45%. In the pressure side, the effect of OF? was associated with a similar effect on porosity (as in OF alone) but ESWT also induced a significant decrease in volumetric bone mineral density, whereas OF alone did not. In the tension side, according to the accelerated tooth movement, a difference was observed in the newly formed bone between the groups. The number of blood vessels/root and TRAP positive cells were higher after the application of ESWT.

Compression force increased RANKL expression in human PDL cells in a force magnitude dependent manner. The addition of ESWT before pressure application resulted in a decrease in mRNA RANKL expression and an increase in the relative wound density in a magnitude dependent manner up to almost a half the time compared to the pressure group.

In light of the above, it may be concluded that the induction of shockwave therapy during orthodontic tooth movement alternate the expression of different inflammatory cytokines in the PDL. This change might have caused the increase in the rate of tooth movement by accelerating bone resorption in the pressure side and possibly enhancing bone formation in the tension side.

PDL cells under mechanical stress may induce osteoclastogenesis through upregulation of RANKL during orthodontic tooth movement. The addition of ESWT before force application improved cell migration and might have a positive effect on bone formation.