Evaluation of root resorption associated with orthodontic movement in stressed rats.
OBJECTIVE
The aim of this study was to investigate the effects of acute and chronic systemic stress response on orthodontically induced root resorption.


METHODS
Male Wistar rats were restrained during 1 hour a day by stress models of short (3 days) and long duration (40 days), while control group was not submitted to restraint (N.=10/group). The upper left first molars of all rats were moved mesially by a fixed orthodontic appliance exerting 50 g force upon insertion during the last 14 days of the experiment. Then, animals were killed for blood collection and mensuration of plasmatic corticosterone by radioimmunoassay; the tissues around mesial root of the first molar were processed for histological and histochemical techniques with tartrate-resistant acid phosphatase. The degree of root resorption and the number of odontoclasts were evaluated, being the contralateral side of each animal serving as its control (split-mouth design).


RESULTS
The results revealed that the plasmatic levels of corticosterone were significantly higher in both the stressed groups than in the control one. There were no significant differences in the degree of root resorption and in the number of odontoclasts on the root between the 3 groups studied.


CONCLUSIONS
These results indicate that systemic stress alone can not be considered a risk factor for root resorption induced by orthodontic tooth movement.
Hauber Gameiro
G
G
Division of Orthodontics Piracicaba Dental School State University of Campinas - UNICAMP Piracicaba, Brazil. gustavo@gameiro.pro.br
Nouer
D F
DF
Borges De Araújo Magnani
M B
MB
Duarte Novaes
P
P
Bovi Ambrosano
G M
GM
Da Silva Andrade
A
A
Ferraz De Arruda Veiga
M C
MC
D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D015415:Biomarkers; D002452:Cell Count; D003345:Corticosterone / Q000097:blood; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008963:Molar / Q000201:enzymology / Q000473:pathology; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances / Q000009:adverse effects*; D010010:Osteoclasts / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D012391:Root Resorption / Q000097:blood / Q000209:etiology* / Q000473:pathology; D013315:Stress, Psychological / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000009:adverse effects* / Q000379:methods
D015415:Biomarkers; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D003345:Corticosterone