Effect of psychological stress on orthodontic tooth movement in rats

Assessment of salivary interleukin-1β (IL-1β), prostaglandin E2 (PGE2) levels and pain intensity in children and adults during initial orthodontic treatment

OBJECTIVES

To investigate pain intensity, interleukin-1β and prostaglandin E₂ values in saliva during initial orthodontic treatment among varying age groups and their correlation between these mediators.

MATERIALS AND METHODS

Twenty healthy patients distributed equally in age and gender groups were chosen. Unstimulated saliva was collected before the placement of orthodontic fixed appliance (T₀), 1 hour after the placement of the appliance with 0.014" nickel titanium archwire (T₁), 1 month after the first visit (T₂), and 1 hour after the placement of 0.016" nickel titanium archwire (T₃). The saliva samples were then analyzed for prostaglandin E₂ and interleukin-1β using enzyme-linked immunosorbent assay. Pain intensity was measured using a numerical rating scale.

RESULTS

Prostaglandin E₂ and interleukin-1β levels had increased at T₁ followed by a drop at T₂ and a subsequent increase at T₃. The prostaglandin E₂ and interleukin-1β levels were higher in adults than children. There was an insignificant correlation between the interleukin-1β and prostaglandin E₂ changes in all the patients. No significant differences were seen in pain scores between adults and children. Insignificant correlation was seen between pain scores and prostaglandin E₂ and interleukin-1β.

CONCLUSION

Prostaglandin E₂ and interleukin-1β can be detected in saliva and are increased in during the initial orthodontic treatment but are higher in adults than children. Pain intensity was not significantly different between adults and children.

The effect of pregnancy on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250±25 gr were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05). Conclusion: Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy.

Key words:Pregnancy, rat, orthodontic tooth movement, osteoclast.

The effect of oral contraceptives on orthodontic tooth movement in rat

INTRODUCTION

The purpose of this study was to investigate the effect of ethinyl estradiol/norgestrel - used in some oral contraceptives- on orthodontic tooth movement in Wistar rats.

MATERIAL AND METHODS

Forty eight female three-month old Wistar rats with an average weight of 250 ± 25 gr were divided into two experimental and control groups. One week prior to appliance insertion and during the appliance therapy period, 100 mcg/kg/day of ethinyl estradiol and 1 mg/kg/days of norgestrel were administered to the experimental group by gavage; meanwhile the control group received an equivalent volume of Sodium Chloride 0.9 % (Saline). Maxillary central incisors were tipped distally by insertion of springs exerting 30 g force. Two, seven and fourteen days after spring insertion animals were sacrificed. The mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared for histomorphometric studies.

RESULTS

14 days after force application the orthodontic tooth movement was significantly lower in the experimental group (p<0.05). The number of osteoclasts were significantly lower in the experimental group 2, 7 and 14 days after spring insertion (p<0.05).

CONCLUSION

Ethinyl estradiol/norgestrel (oral contraceptives) can significantly decrease the amount of tooth movement in the linear phase.