Effect of cyclical forces on the periodontal ligament and alveolar bone remodeling during orthodontic tooth movement

ABSTRACT Objective: To investigate the effect of externally applied cyclical (vibratory) forces on the rate of tooth movement, the structural integrity of the periodontal ligament, and alveolar bone remodeling. Methods: Twenty-six female Sprague-Dawley rats (7 weeks old) were divided into four groups: CTRL (unloaded), VBO (molars receiving a vibratory stimulus only), TMO (molars receiving an orthodontic spring only), and TMO+VB (molars receiving an orthodontic spring and the additional vibratory stimulus). In TMO and TMO+VB groups, the rat first molars were moved mesially for 2 weeks using Nickel-Titanium coil spring delivering 25 g of force. In VBO and TMO+VB groups, cyclical forces at 0.4 N and 30 Hz were applied occlusally twice a week for 10 minutes. Microfocus X-ray computed tomography analysis and tooth movement measurements were performed on the dissected rat maxillae. Tartrate-resistant acid phosphatase staining and collagen fiber assessment were performed on histological sections. Results: Cyclical forces significantly inhibited the amount of tooth movement. Histological analysis showed marked disorganization of the collagen fibril structure of the periodontal ligament during tooth movement. Tooth movement caused a significant increase in osteoclast parameters on the compression side of alveolar bone and a significant decrease in bone volume fraction in the molar region compared to controls. Conclusions: Tooth movement was significantly inhibited by application of cyclical forces.

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Effect of Curcumin on Alterations of Alveolar Bone Remodeling and Expression of Receptor Activator of Nuclear Factor-κ B Ligand in Rat Tooth During Tooth Movement

Journal of Biomaterials and Tissue Engineering ◽

10.1166/jbt.2021.2779 ◽

2021 ◽

Vol 11 (10) ◽

pp. 2058-2063

Author(s):

Yang An ◽

Zhenqiang Li ◽

Li An ◽

Qingmei Liu

Keyword(s):

Bone Remodeling ◽

Alveolar Bone ◽

Tooth Movement ◽

Volume Fraction ◽

Micro Ct ◽

Bone Volume Fraction ◽

Alveolar Bone Remodeling ◽

Receptor Activator ◽

Trabecular Density ◽

Movement Distance

Objective: To evaluate the effect of Curcumin on Alterations of Alveolar Bone Remodeling and Expression of RANKL in Rat Tooth during Tooth Movement. Methods: 64 SD rats were randomly divided into 4 groups, Model, Adrb2, Cur and Cur + Pro groups. The rat orthodontic teeth movement models were established.The rats were injected corresponding reagents according to weight and were sacrificed on day 0, 7, 14 and 21. The movement distance of first molar of rats was measured by Vernier caliper.The numbers of osteoclasts were observed through TRAP staining. The change of micro-structure of alveolar bone was evaluated by Micro-CT. Results: The trends of the distance of teeth movement and numbers of osteoclast were the same: Cur group β Adrb2 group > Model groups Cur+Pro group (P < 0.05). Micro-CT scan showed that curcumin could reduce the bone volume fraction (BV/TV), bone trabecular density (MTPD), and increase the trabecular resolution (TB. SP). When propranolol was given at the same time, the effect of curcumin disappeared. Conclusion: Curcumin could promote the resorption of alveolar bone at the pressure side and increase the osteoclast numbers so that the alveolar bone became looser which was beneficial to the movement of orthodontic tooth.

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Mechanosensitive Piezo1 in Periodontal Ligament Cells Promotes Alveolar Bone Remodeling During Orthodontic Tooth Movement

Frontiers in Physiology ◽

10.3389/fphys.2021.767136 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yukun Jiang ◽

Yuzhe Guan ◽

Yuanchen Lan ◽

Shuo Chen ◽

Tiancheng Li ◽

...

Keyword(s):

Bone Remodeling ◽

Periodontal Ligament ◽

Alveolar Bone ◽

Tooth Movement ◽

Critical Role ◽

Orthodontic Tooth Movement ◽

Chemical Signals ◽

Periodontal Tissues ◽

Alveolar Bone Remodeling ◽

Pdl Cells

Orthodontic tooth movement (OTM) is a process depending on the remodeling of periodontal tissues surrounding the roots. Orthodontic forces trigger the conversion of mechanical stimuli into intercellular chemical signals within periodontal ligament (PDL) cells, activating alveolar bone remodeling, and thereby, initiating OTM. Recently, the mechanosensitive ion channel Piezo1 has been found to play pivotal roles in the different types of human cells by transforming external physical stimuli into intercellular chemical signals. However, the function of Piezo1 during the mechanotransduction process of PDL cells has rarely been reported. Herein, we established a rat OTM model to study the potential role of Piezo1 during the mechanotransduction process of PDL cells and investigate its effects on the tension side of alveolar bone remodeling. A total of 60 male Sprague-Dawley rats were randomly assigned into three groups: the OTM + inhibitor (INH) group, the OTM group, and the control (CON) group. Nickel-titanium orthodontic springs were applied to trigger tooth movement. Mice were sacrificed on days 0, 3, 7, and 14 after orthodontic movement for the radiographic, histological, immunohistochemical, and molecular biological analyses. Our results revealed that the Piezo1 channel was activated by orthodontic force and mainly expressed in the PDL cells during the whole tooth movement period. The activation of the Piezo1 channel was essential for maintaining the rate of orthodontic tooth movement and facilitation of new alveolar bone formation on the tension side. Reduced osteogenesis-associated transcription factors such as Runt-related transcription factor 2 (RUNX2), Osterix (OSX), and receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio were examined when the function of Piezo1 was inhibited. In summary, Piezo1 plays a critical role in mediating both the osteogenesis and osteoclastic activities on the tension side during OTM.

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Raloxifene administration enhances retention in an orthodontic relapse model

European Journal of Orthodontics ◽

10.1093/ejo/cjaa008 ◽

2020 ◽

Vol 42 (4) ◽

pp. 371-377

Author(s):

Niloufar Azami ◽

Po-Jung Chen ◽

Shivam Mehta ◽

Zana Kalajzic ◽

Eliane H Dutra ◽

...

Keyword(s):

Alveolar Bone ◽

Tooth Movement ◽

Volume Fraction ◽

Orthodontic Tooth Movement ◽

Bone Volume ◽

Resin Cement ◽

Control Group ◽

Tartrate Resistant Acid Phosphatase ◽

Bone Volume Fraction ◽

Tissue Density

Abstract Background and objectives Orthodontic relapse is a physiologic process that involves remodelling of the alveolar bone and principle periodontal ligament fibres. Raloxifene is an Food and Drug Administration (FDA)-approved selective oestrogen receptor modulator that inhibits systemic bone loss. In our study, we examined the effects of Raloxifene on alveolar bone modelling and orthodontic relapse in a rodent model. Materials and methods The efficacy of raloxifene was evaluated in 15-week-old male Wistar rats, 8 in each group (Control, Raloxifene, Raloxifene + 7-day relapse, Raloxifene + 14-day relapse) for a total of 42 days. All animals had 14 days of orthodontic tooth movement with a closed nickel–titanium coil spring tied from incisors to right first molar applying 5–8 gm of force. On the day of appliance removal, impression was taken with silicon material and the distance between first molar and second molar was filled with light-cured adhesive resin cement for retention phase. Raloxifene Retention, Raloxifene Retention + 7D, Raloxifene Retention + 14D groups received 14 daily doses of raloxifene (2.0 mg/kg/day) subcutaneously after orthodontic tooth movement during retention. After 14 days of retention, the retainer was removed and right first molar was allowed to relapse for a period of 14 days. Raloxifene injection continued for the Raloxifene + 14-day relapse group during relapse phase too. Control group received saline injections during retention. Animals were euthanized by CO2 inhalation. The outcome measure included percentage of relapse, bone volume fraction, tissue density, and histology analysis using tartrate-resistant acid phosphatase staining and determining receptor activator of nuclear factor-кB-ligand (RANKL) and osteoprotegerin expression. Results Raloxifene Retention + 14D group had significantly less (P < 0.05) orthodontic relapse when compared with other groups. There was a significant increase (P < 0.05) in bone volume fraction and tissue density in the Raloxifene Retention + 14D group when compared with other groups. Similarly, there was significant decrease in number of osteoclasts and RANKL expression in Raloxifene Retention + 14D group when compared with Raloxifene Retention + 7D group (P < 0.05). Conclusion Raloxifene could decrease post-orthodontic treatment relapse by decreasing bone resorption and indirectly enhancing bone formation.

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Comparison of the effects of three surgical techniques on the rate of orthodontic tooth movement in a rat model

The Angle Orthodontist ◽

10.2319/123016-940.1 ◽

2017 ◽

Vol 87 (5) ◽

pp. 717-724 ◽

Cited By ~ 10

Author(s):

Zachary Librizzi ◽

Zana Kalajzic ◽

Daniel Camacho ◽

Sumit Yadav ◽

Ravindra Nanda ◽

...

Keyword(s):

Rat Model ◽

Alveolar Bone ◽

Tooth Movement ◽

Volume Fraction ◽

Surgical Techniques ◽

Orthodontic Tooth Movement ◽

Tartrate Resistant Acid Phosphatase ◽

Bone Volume Fraction ◽

Bone Response ◽

Mucoperiosteal Flap

ABSTRACT Objective: To evaluate the effect of corticotomy and corticision, with and without a full mucoperiosteal flap, on the rate of tooth movement and alveolar response in a rat model. Materials and Methods: Sixty male, 6-week-old Wistar rats were divided into five groups based on surgical procedure, as follows: control (no tooth movement), orthodontic tooth movement (OTM) only, corticotomy, corticision, and corticision with full mucoperiosteal flap (corticision + flap). A force of 10–15g was applied from the maxillary left first molar to the maxillary incisors using nickel-titanium springs. Surgery was performed at the time of appliance placement (day 0), and tooth movement occurred for 21 days. Micro–computed tomography was performed on day 21 to evaluate the amount of tooth movement and alveolar bone parameters. Histomorphometry, including tartrate-resistant acid phosphatase staining, was performed to quantify the osteoclast parameters at day 21. Results: No statistical differences in the amount of OTM, bone volume fraction, and tissue density and the osteoclast parameters were found among all experimental groups. Conclusions: Corticotomy and corticision, with or without a full mucoperiosteal flap, did not show a significant effect on either the OTM magnitude or alveolar bone response.

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The effect of differential force system and minimal surgical intervention on orthodontic tooth movement and root resorption

European Journal of Orthodontics ◽

10.1093/ejo/cjaa065 ◽

2020 ◽

Author(s):

Anjali Nanda ◽

Po-Jung Chen ◽

Shivam Mehta ◽

Zana Kalajzic ◽

Eliane H Dutra ◽

...

Keyword(s):

Wistar Rats ◽

Alveolar Bone ◽

Tooth Movement ◽

Root Resorption ◽

Volume Fraction ◽

Orthodontic Tooth Movement ◽

Primary Objective ◽

Tartrate Resistant Acid Phosphatase ◽

Bone Volume Fraction ◽

Force System

Summary Objective The primary objective of this study was to quantify the orthodontic tooth movement (OTM) and orthodontically induced root resorption (OIRR) with differential force system in conjunction with minimal surgical insult. Material and methods 15-week-old, 48 male Wistar rats were used in the research and were randomly divided into six groups: 1. Group 1 (8 Wistar rats): OTM for 14 days with 8-g force; 2. Group 2 (8 Wistar rats): OTM for 14 days with 25-g force; 3. Group 3 (8 Wistar rats): OTM for 14 days with 100-g force; 4. Group 4 (8 Wistar rats): OTM for 14 days with 8-g force and alveolar decortications (ADs); 5. Group 5 (8 Wistar rats): OTM for 14 days with 25-g force and ADs; 6. Group 6 (8 Wistar rats): OTM for 14 days with 100-g force and ADs. A nickel–titanium spring was used to protract the molar mesially using maxillary incisors as an anchorage. ADs (minimal surgical insult) were done using a hand piece and a round bur, adjacent to the left first maxillary molar on the palatal alveolar bone. After 14 days of OTM, Wistar rats were killed and microfocus computed tomography and histological analysis were performed. Results The 100-g group showed significant increase (P < 0.05) in OTM. However, with ADs, the OTM was significantly higher (P < 0.05) in 8 and 100 g. In addition, with ADs, there is significant increase (P < 0.05) in OIRR and significant decrease (P < 0.05) in bone volume fraction. Histological quantification of tartrate-resistant acid phosphatase indicated a significant increase (P < 0.05) in the number of osteoclasts with ADs when compared without ADs. Conclusions Light force in conjunction with ADs are optimal to accelerate the OTM. Additionally, ADs increases the OIRR.

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Expression of Connexin 43 in Rat Mandibular Bone and Periodontal Ligament (PDL) Cells during Experimental Tooth Movement

Journal of Dental Research ◽

10.1177/00220345970760070501 ◽

1997 ◽

Vol 76 (7) ◽

pp. 1357-1366 ◽

Cited By ~ 62

Author(s):

M. Su ◽

J.L. Borke ◽

H.J. Donahue ◽

Z. Li ◽

N.M. Warshawsky ◽

...

Keyword(s):

Bone Remodeling ◽

Periodontal Ligament ◽

Connexin 43 ◽

Alveolar Bone ◽

Tooth Movement ◽

Cdna Probe ◽

Periodontal Ligament Cells ◽

Alveolar Bone Remodeling ◽

Junction Protein ◽

Experimental Tooth Movement

Bone remodeling in response to force requires the coordinated action of osteoblasts, osteoclasts, osteocytes, and periodontal ligament cells. Coordination among these cells may be mediated, in part, by cell-to-cell communication via gap junctions. This study tests the hypothesis that the regulation of expression of connexin 43, a gap junction protein, is part of the transduction mechanism between force as applied to bone during orthodontic tooth movement and bone remodeling. To test this hypothesis, we examined connexin 43 expression in a rat model system of experimental tooth movement. To establish the model, we extracted maxillary first molars to initiate supra-eruption of opposing mandibular molars. The rats were killed at 0, 6, 12, 24, and 48 hrs post-extraction. The mandibles were removed, demineralized, and embedded in paraffin. To localize connexin 43 protein and mRNA, we used a specific antibody for immunohistochemistry and a specific cDNA probe for in situ hybridization. Western and Northern blot analyses were used to assess the specificity of the connexin 43 antibody and cDNA probe, respectively. We found connexin 43 protein expressed by osteoclasts (++++) and periodontal ligament cells (+++) in compression zones, and by osteoblasts (++++) and osteocytes (++++) in tension zones of the periodontal ligament. In addition, connexin 43 mRNA was found in some bone and periodontal ligament cells. Connexin 43 protein was found, by densitometric analysis, to be higher in the periodontal ligament after exposure to force compared with controls (P < 0.001). The number of osteocytes expressing connexin 43 48 hrs after molar extraction was also significantly greater in bone subjected to tension when compared with controls (P < 0.001). The results of this study support the hypothesis that connexin 43 plays a role in the coordination of events during experimentally induced alveolar bone remodeling.

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Orthodontic Force–Induced BMAL1 in PDLCs Is a Vital Osteoclastic Activator

Journal of Dental Research ◽

10.1177/00220345211019949 ◽

2021 ◽

pp. 002203452110199

Author(s):

Y. Xie ◽

Q. Tang ◽

S. Yu ◽

W. Zheng ◽

G. Chen ◽

...

Keyword(s):

Bone Remodeling ◽

Alveolar Bone ◽

Tooth Movement ◽

Orthodontic Tooth Movement ◽

Nuclear Factor Κb ◽

Periodontal Ligament Cells ◽

Orthodontic Force ◽

Periodontal Tissues ◽

Alveolar Bone Remodeling ◽

Biomechanical Stimuli

Orthodontic tooth movement (OTM) depends on periodontal ligament cells (PDLCs) sensing biomechanical stimuli and subsequently releasing signals to initiate alveolar bone remodeling. However, the mechanisms by which PDLCs sense biomechanical stimuli and affect osteoclastic activities are still unclear. This study demonstrates that the core circadian protein aryl hydrocarbon receptor nuclear translocator–like protein 1 (BMAL1) in PDLCs is highly involved in sensing and delivering biomechanical signals. Orthodontic force upregulates BMAL1 expression in periodontal tissues and cultured PDLCs in manners dependent on ERK (extracellular signal–regulated kinase) and AP1 (activator protein 1). Increased BMAL1 expression can enhance secretion of CCL2 (C-C motif chemokine 2) and RANKL (receptor activator of nuclear factor–κB ligand) in PDLCs, which subsequently promotes the recruitment of monocytes that differentiate into osteoclasts. The mechanistic delineation clarifies that AP1 induced by orthodontic force can directly interact with the BMAL1 promoter and activate gene transcription in PDLCs. Localized administration of the ERK phosphorylation inhibitor U0126 or the BMAL1 inhibitor GSK4112 suppressed ERK/AP1/BMAL1 signaling. These treatments dramatically reduced osteoclastic activity in the compression side of a rat orthodontic model, and the OTM rate was almost nonexistent. In summary, our results suggest that force-induced expression of BMAL1 in PDLCs is closely involved in controlling osteoclastic activities during OTM and plays a vital role in alveolar bone remodeling. It could be a useful therapeutic target for accelerating the OTM rate and controlling pathologic bone-remodeling activities.

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Effects of sialoadenectomy and exogenous EGF on molar drift and orthodontic tooth movement in rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1994.266.5.e731 ◽

1994 ◽

Vol 266 (5) ◽

pp. E731-E738 ◽

Cited By ~ 2

Author(s):

C. Dolce ◽

J. Anguita ◽

L. Brinkley ◽

P. Karnam ◽

M. Humphreys-Beher ◽

...

Keyword(s):

Bone Formation ◽

Bone Remodeling ◽

Alveolar Bone ◽

Tooth Movement ◽

Orthodontic Tooth Movement ◽

Alveolar Bone Remodeling ◽

Tooth Roots ◽

Epidermal Growth ◽

Tetracycline Labeling ◽

Distal Aspect

Effects on bone remodeling have been attributed to epidermal growth factor (EGF). Sialoadenectomy (SX) removes the major source of EGF in rodents and decreases both salivary and serum EGF levels. EGF effects on rat alveolar bone remodeling manifested by molar drift (MD) and orthodontic tooth movement (OTM) were examined using the following two approaches: 1) EGF depletion by SX and replacement by orally administered EGF (50 micrograms.animal-1.day-1); 2) sham rats supplemented with matching amounts of EGF. MD and OTM were measured using cephalometric radiographs; bone formation was measured histomorphometrically using tetracycline labeling. Normal MD was not detected after SX, and alveolar bone formation was significantly reduced both around the tooth and in nondental sites. Replacement EGF given to SX rats and supplemental EGF administered to sham rats changed the direction and enhanced the rate of MD. A mesially directed orthodontic force applied to the molars of SX animals increased bone formation on the distal aspect of the tooth roots. Supplemental EGF did not significantly affect OTM. EGF affects alveolar bone remodeling, as manifested clinically by alterations in normal maxillary MD.

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Effects of different force magnitudes on corticotomy-assisted orthodontic tooth movement in rats

The Angle Orthodontist ◽

10.2319/103117-736.1 ◽

2018 ◽

Vol 88 (5) ◽

pp. 632-637 ◽

Cited By ~ 4

Author(s):

Kriangkrai Kraiwattanapong ◽

Bancha Samruajbenjakun

Keyword(s):

Alveolar Bone ◽

Tooth Movement ◽

Root Resorption ◽

Volume Fraction ◽

Micro Ct ◽

Histomorphometric Analysis ◽

Bone Volume Fraction ◽

Bone Response ◽

Significant Difference ◽

Light Force

ABSTRACT Objectives: To investigate the effects of light and heavy forces with corticotomy on tooth movement rate, alveolar bone response, and root resorption in a rat model. Materials and Methods: The right and left sides of 40 male Wistar rats were randomly assigned using the split-mouth design to two groups: light force with corticotomy (LF) and heavy force with corticotomy (HF). Tooth movement was performed on the maxillary first molars using a nickel-titanium closed-coil spring delivering either 10 g (light force) or 50 g (heavy force). Tooth movement and alveolar bone response were assessed by micro–computed tomography (micro-CT) at day 0 as the baseline and on days 7, 14, 21, and 28. Root resorption was examined by histomorphometric analysis at day 28. Results: Micro-CT analysis showed a significantly greater tooth movement in the HF group at days 7 and 14 but no difference in bone volume fraction at any of the observed periods. Histomorphometric analysis found no significant difference in root resorption between the LF and HF groups at day 28. Conclusions: Heavy force with corticotomy increased tooth movement at days 7 and 14 but did not show any difference in alveolar bone change or root resorption.

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