The effect of bone morphometric changes on orthodontic tooth movement in an osteoporotic animal model

Abstract

Objective: To elucidate the effect of bone morphometric changes on orthodontic tooth movement (OTM) in zoledronic acid-treated ovariectomized rats. Materials and Methods: Twenty-one 10-week-old female Wistar rats were divided into ovariectomy (OVX), OVX with zoledronic acid administration (OVX + ZOL), and sham operation (control) groups. Two weeks after OVX, ZOL administration was initiated. Twelve weeks after OVX, a nickel-titanium closed-coil spring of 25-g force was applied mesially to the maxillary left first molar. In vivo micro-computed tomography (CT) of the left proximal tibia was performed for bone morphometric analysis every 2 weeks after OVX. In addition, OTM was investigated using micro-CT at 0, 12, and 14 weeks after OVX. Results: There were significant differences in the bone mineral content (BMC), bone volume (BV), BMC to tissue volume ratio (BMC/TV), and BV to TV ratio of trabecular bone between the control and OVX groups and also between the OVX + ZOL and OVX groups. In the OVX + ZOL group, increased BMC and BV in the cortical bone and increased bone mineral density (BMD) in the trabecular bone were observed. Interestingly, OTM in the OVX group was almost two times more than that in the control and OVX + ZOL groups. Moreover, OTM was correlated with BMD, BMC, BV, and BMC/TV in the trabecular bone. Conclusions: OVX accelerated OTM, while ZOL suppressed it. OTM demonstrated a significant negative relationship with trabecular bone mass. (Angle Orthod. 2013;83:766-773.)

Metformin as an add‐on to insulin improves periodontal response during orthodontic tooth movement in type 1 diabetic rats

“…In contrast, a lower rate of tooth displacement and alveolar bone turnover in T1D rats without treatment was reported. These studies do not agree with the substantial evidence linking T1D to osteopenia, osteoporosis, and related cellular and molecular mechanisms, or with studies showing a higher rate of tooth displacement and root resorption in T1D individuals . Therefore, our results suggest that T1D induces fragile bone that cannot support light forces that in turn become too excessive for the periodontal structures leading to breakdown and a different OTM pattern.…”

“…These studies do not agree with the substantial evidence linking T1D to osteopenia, 3 osteoporosis, 12 and related cellular and molecular mechanisms, 3,34 or with studies showing a higher rate of tooth displacement and root resorption in T1D individuals. 46,47 Therefore, our results suggest that T1D induces fragile bone that cannot support light forces that in turn become too excessive for the periodontal structures leading to breakdown and a different OTM pattern. Generally, the impaired bone metabolism in T1D children and adolescents reduces peak bone accrual, predisposing the adult to osteopenia and osteoporosis.…”

The effects of binge-pattern alcohol consumption on orthodontic tooth movement

“…The device used to induce OTM consisted of a nickel-titanium closed coil spring (G&H (r) Wire - Franklin, Indiana, USA) attached to maxillary right first molar and central incisors of all animals, which produced a 25-cN reciprocal force 14. Measurement of the force produced by the coil spring was standardized by means of a calibrated dynamometer (Haag-Streit AG, Switzerland Koeniz, Switzerland).…”

Lithium chloride reduces orthodontically induced root resorption and affects tooth root movement in rats

“…Various factors have been reported to influence OTM. 6,7 Hashimoto et al 8 reported a negative correlation between OTM and bone morphometric measurements, such as trabecular bone structure in ovariectomized rats. It was also reported that tooth movement increased and the optical density of bone decreased on administration of fluoxetine to the rats.…”