Methods: Patients previously treated in the Orthodontics Department at Sydney University were selected based on moderate to severe OIIRR assessed via orthopantogram. Blood chemistry was assessed through collection of fasting blood samples and unstimulated saliva was collected by expectoration into polypropylene tubes with protease inhibitors for saliva chemistry. Multiplex ELISA Arrays were used to screen blood and saliva samples for Human Cytokines, chemokines and several key enzymes that may play a role in root resorption following orthodontic force application.
Results: There is a significant increase in salivary cytokines interleukin-7, interleukin-10 interleukin- 12p70 and interferon-gamma as well as a significant decrease in interleukin-4 in patients with moderate to severe OIIRR. There was a significant increase in osteocalcin and Procollagen Type I N-Terminal Peptide (P1NP) in control groups, however gender differences provided greater significance in osteocalcin and P1NP values.
Conclusions: The weak association of treatment variables and patient characteristics with the degree of root resorption suggests that increased expression of pro-inflammatory as well as anti- inflammatory cytokines may be determinants in the development of moderate to severe root resorption. However, the cytokine expression may be affected by any other potential inflammation in the body.
This study also found that saliva may be more effective in measuring changes in cytokine expression than blood.
Osteocalcin and P1NP appeared to be the only blood factors that showed a significant difference in control groups. However, gender had a greater significance on osteocalcin and P1NP levels than control or OIIRR groups.