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

Effect of Lithium on Orthodontic Tooth Movement: a Systematic Review of Animal Studies

Objective

This study aimed to systematically review the effect of lithium on orthodontic tooth movement (OTM).

Methods

The focus question was "does lithium have an effect on OTM?" A systematic search was conducted using indexed databases and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. The quality assessment of the selected studies was performed according to the systematic review center for laboratory animal experimentation.

Results

Five of the initially identified 656 articles fulfilled the eligibility criteria and were selected for this review. The studies reported that lithium administration lowered the rate of OTM by inducing a reduction in the number of osteoclasts and possibly inhibiting osteoclastogenesis. These studies further showed an increase in bone density and bone volume by promoting the Wnt/ß-catenin signaling pathway and osteoblastogenesis. It was also noted that lithium reduced orthodontically induced root resorption during experimental OTM. Further, standardized studies are warranted to understand the impact of lithium in OTM. Overall, the risk of bias for 3 studies was very high, high in 1 study, and moderate in 1 study.

Conclusion

On an experimental level in animals, lithium decreased the rate of OTM during the active treatment phase by increasing bone density and bone volume and reducing root resorption. In addition, lithium may enhance alveolar bone formation during orthodontic retention. Clinically, this may impact the orthodontic treatment duration in patients receiving lithium, and further studies are needed to understand the true impact of lithium on OTM.

Lithium chloride stimulates bone formation in extraction socket repair in rats

PURPOSE

Previous evidence shows that lithium chloride (LiCl), a suppressor of glycogen synthase kinase-3β (GSK-3β), may enhance bone formation in several medical and dental conditions. Thus, the purpose of the current study was to assess the effects of LiCl on extraction socket repair in rats.

METHODS

Thirty rats were randomly assigned into a control group (administration of water; n = 15) or a LiCl group (administration of 150 mg/kg of LiCl; n = 15). LiCl and water were given every other day, starting at 7 days before the extraction of upper first molars until the end of each experiment period. Histological sections from five rats per group were obtained at 10, 20, and 30 days post-extractions. Histometrical analysis of newly formed bone (NB) and the levels of tartrate-resistant acid phosphatase (TRAP)-stained cells were evaluated at 10, 20, and 30 days post-extractions. Immunohistochemical staining for receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) was assessed at 10 days post-extractions.

RESULTS

The LiCl group had a greater proportion of NB than the control group at 20 days (P < 0.05). At 30 days, the rate of TRAP-stained cells was lower in the LiCl group than in the control group (P < 0.05). At 10 days, the LiCl group presented stronger staining for OPG, BSP, OPN, and OCN, when compared to the control group (P < 0.05).

CONCLUSION

Systemic LiCl enhanced extraction socket repair, stimulated an overall increase in bone formation markers, and restricted the levels of TRAP in rats.

Effects of green tea extract epigallocatechin-3-gallate (EGCG) on orthodontic tooth movement and root resorption in rats

OBJECTIVE

To study the effect of EGCG on tooth movement and root resorption during orthodontic treatment in rats.

METHODS

A total of thirty six male Wistar rats were randomly and equally divided into three groups: control, 50 mg/kg EGCG, and 100 mg/kg EGCG. During the experiment, the subjects were submitted to an orthodontic tooth movement (OTM) model, rats in the experimental groups were given the corresponding dose of EGCG, while rats in the control group were administrated with an equal volume of normal saline solution by gavage. After 14 days of OTM, the rats were sacrificed by transcardial perfusion. Micro-CT of rat maxillaes was taken to analyze OTM distance and root resorption. The maxillary samples were prepared as histological sections for H&E staining, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical (IHC) staining to be observed and analyzed.

RESULTS

The OTM distance and root resorption of rats in the dosed group decreased, and the number of TRAP positive cells in their periodontium decreased significantly. The expression level of RANKL was decreased in the EGCG group compared to the control group, while that of OPG, OCN and Runx2 was increased. Effects were more pronounced in 100 mg/kg group than in 50 mg/kg group.

CONCLUSION

EGCG reduces OTM and orthodontic induced root resorption (OIRR) in rats, and is able to attenuate osteoclastogenesis on the pressure side and promote osteogenesis on the tension side.

Targeted next-generation sequencing for comprehensive genetic analysis of external apical root resorption during orthodontic treatment with premolar extraction in the Korean population

INTRODUCTION

External apical root resorption (EARR) is one of the most common unfavorable consequences of orthodontic treatment and causes loss of tooth structure. The present study aimed to investigate the genetics of EARR using next-generation sequencing comprehensively.

METHODS

Targeted next-generation sequencing was performed for comprehensive genetic analysis of 118 Korean orthodontic patients. The patients were divided into 2 groups on the basis of their EARR value. The association of clinical and genetic parameters with EARR was assessed using the χ2 test or t test for matched pairs, followed by Bonferroni correction and linear regression analysis. In addition, haplotype analysis and in silico prediction were conducted to evaluate functional effects.

RESULTS

No statistically significant difference was observed between clinical and treatment-related parameters and EARR. The single nucleotide polymorphisms SPP1 rs9138 (P = 0.001) and SFRP2 rs3810765 (P = 0.04) showed only nominal significance between EARR groups. However, these 2 SNPs were not significant after Bonferroni correction for multiple testing (cutoff P = 0.05/142 = 3.52 × 10-4). Variations in SPP1 rs9138 and SFRP2 rs3810765 may be related to EARR during orthodontic treatment. In summary, not only genes related to inflammatory reactions but also those related to Wnt signaling to affect the degree of EARR during orthodontic teeth movement.

Sinomenine Inhibits Orthodontic Tooth Movement and Root Resorption in Rats and Enhances Osteogenic Differentiation of PDLSCs

Purpose

To investigate the effects of sinomenine on orthodontic tooth movement and root resorption in rats, as well as the effect of sinomenine on the osteogenesis of periodontal ligament stem cells (PDLSCs).

Methods

Fifty-four male Wistar rats were randomly divided into 3 groups: control group, 20 mg/kg sinomenine group and 40 mg/kg sinomenine group. Fifty-gram orthodontic force was applied to all groups. Each group was injected intraperitoneally with corresponding concentration of sinomenine every day. After 14 days, all rats were sacrificed. Micro-computed tomography (micro-CT) scan was used to analyze tooth movement, root resorption and alveolar bone changes. The effect on periodontal tissue was analyzed by Masson, tartrate-resistant acid phosphatase (TRAP) and immunohistochemical staining. In vitro, PDLSCs were extracted and identified. The effect of sinomenine on proliferation was determined by cell-counting kit-8. The effect of sinomenine on osteogenesis was investigated by alkaline phosphatase (ALP) activity and alizarin red staining. qPCR and Western blotting were performed to explore the effects of sinomenine on the expression levels of ALP, runt-related transcription factor 2 (RUNX2), receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG).

Results

The tooth movement and root resorption of sinomenine groups were reduced. Sinomenine decreased trabecular spacing on compression side and increased alveolar bone volume and trabecular thickness on tension side. TRAP-positive cells in sinomenine groups decreased significantly. The expressions of TNF-α and RANKL were decreased, while the expressions of OPG, RUNX2 and osteocalcin were up-regulated. In vitro, 0.1 M and 0.5 M sinomenine enhanced ALP activity, mineral deposition and the expression of ALP, RUNX2 and OPG, and reduced the expression of RANKL.

Conclusion

Sinomenine could inhibit tooth movement, reduce root resorption, and exert a positive effect on bone formation in rats. Moreover, sinomenine promoted the osteogenesis of PDLSCs.

Lithium reduces orthodontically induced root resorption by suppressing cell death, hyalinization, and odontoclast formation in rats

OBJECTIVES

To examine whether lithium suppresses orthodontically induced root resorption (OIRR) via two mechanisms (prevention of hyalinization in periodontal tissue and suppression of odontoclasts) and to investigate the changes in the periodontal tissue and alveolar bone, focusing on the appearance of cell death, hyalinization, and odontoclasts.

MATERIALS AND METHODS

The maxillary first molars of 10-week-old male Wistar rats were moved mesially by a closed-coil spring for 14 days. Lithium chloride (LiCl; 0.64 mM/kg) or saline (control) was administered intraperitoneally daily. Tooth movements were measured using micro-computed tomography. Appearances of cell death, hyalinization, and odontoclasts were evaluated by histological analysis.

RESULTS

OIRR observed on day 14 in the control group was suppressed strongly by LiCl administration. Apoptotic cells observed on day 1 in the compression area were gradually diminished on days 2 and 3 and transformed to hyalinization tissue in the control group. LiCl administration remarkably suppressed this cell death and subsequent hyalinization. Also, the appearance of odontoclasts in the compression area observed on day 7 was significantly suppressed by LiCl administration. Accordingly, these degenerative processes to OIRR were suppressed substantially by LiCl treatment.

CONCLUSIONS

Lithium reduces OIRR through the suppression of periodontal ligament cell death, hyalinization, and odontoclast formation.

Lithium chloride promotes osteogenesis and suppresses apoptosis during orthodontic tooth movement in osteoporotic model via regulating autophagy

Osteoporosis is a widely distributed disease that may cause complications such as accelerated tooth movement, bone resorption, and tooth loss during orthodontic treatment. Promoting bone formation and reducing bone resorption are strategies for controlling these complications. For several decades, the autophagy inducer lithium chloride (LiCl) has been explored for bipolar . In this study, we investigated the autophagy-promoting effect of LiCl on bone remodeling under osteoporotic conditions during tooth movement. Ovariectomy was used to induce osteoporosis status in vivo. The results showed that LiCl rejuvenated autophagy, decreased apoptosis, and promoted bone formation, thus protecting tooth movement in osteoporotic mice. Furthermore, in vitro experiments showed that LiCl reversed the effects of ovariectomy on bone marrow-derived mesenchymal stem cells (BMSCs) extracted from ovariectomized mice, promoting osteogenesis and suppressing apoptosis by positively regulating autophagy. These findings suggest that LiCl can significantly decrease adverse effects of osteoporosis on bone remodeling, and that it has great potential significance in the field of bone formation during tooth movement in osteoporosis patients.

Systemic Lithium Chloride Administration Improves Tooth Extraction Wound Healing in Estrogen-Deficient Rats

The purpose of this investigation was to evaluate the effects of lithium chloride (LiCl) on the socket healing of estrogen-deficient rats. Seventy-two rats were allocated into one of the following groups: Control, Ovariectomy and LiCl (150 mg/kg/2 every other day orally) + Ovariectomy. Animals received LiCl or water from the 14th day post-ovariectomy, until the completion of the experiment. On the 21st day after ovariectomy, the first molars were extracted. Rats were euthanized on the 10th, 20th and 30th days following extractions. Bone healing (BH), TRAP positive cells and immunohistochemical staining for OPG, RANKL, BSP, OPN and OCN were evaluated. The Ovariectomy group presented decreased BH compared to the LiCl group at 10 days, and the lowest BH at 20 days (p<0.05). At 30 days, the Ovariectomy and LiCl-groups presented lower BH than that of the Control (p<0.05). The number of TRAP-stained cells was the lowest in the LiCl group at 20 days and the highest in the Ovariectomy group at 30 days (p<0.05). At 10 days of healing, the LiCl group demonstrated stronger staining for all bone markers when compared to the other groups, while the Ovariectomy group presented higher RANKL expression than that of the Control (p<0.05). LiCl enhanced bone healing in rats with estrogen deficiency, particularly in the initial healing phases. However, as data on the effects of lithium chloride on bone tissue are still preliminary, more studies related to its toxicity and protocol of administration are necessary before its application in clinical practice.

Effects of systemic medication on root resorption associated with orthodontic tooth movement: a systematic review of animal studies

BACKGROUND

Theoretically, root resorption could be modulated by any medication taken that exhibits possible effects on the implicated molecular pathways.

OBJECTIVES

To systematically investigate and appraise the quality of the available evidence from animal studies, regarding the effect of commonly prescribed systemic medication on root resorption associated with orthodontic tooth movement.

SEARCH METHODS

Search without restrictions in eight databases (PubMed, Central, Cochrane Database of Systematic Reviews, SCOPUS, Web of Science, Arab World Research Source, ClinicalTrials.gov, ProQuest Dissertations and Theses Global) and hand searching until April 2018 took place. One author developed detailed search strategies for each database that were based on the PubMed strategy and adapted accordingly.

SELECTION CRITERIA

Controlled studies investigating the effect of systemic medications on root resorption associated with orthodontic tooth movement.

DATA COLLECTION AND ANALYSIS

Following study retrieval and selection, relevant data were extracted and the risk of bias was assessed using the SYRCLE's Risk of Bias Tool.

RESULTS

Twenty-one studies were finally identified, most of which at unclear risk of bias. Root resorption was shown to increase in Vitamin C treated animals in comparison with the control group, whereas a comparative decrease was noted after the administration of the alendronate, ibuprofen, growth hormone, low doses of meloxicam, simvastatin, lithium chloride and strontium ranelate. No difference was noted for acetaminophen, aspirin, fluoxetine, atorvastatin, misoprostol, zoledronic acid and zinc. Finally, inconsistent effects were observed after the administration of celecoxib, prednisolone and L-thyroxine. The quality of the available evidence was considered at best as low.

CONCLUSIONS

The pharmaceutical substances investigated were shown to exhibit variable effects on root resorption. Although the overall quality of evidence provides the clinician with a cautious perspective on the strength of the relevant recommendations, good practice would suggest that it is important to identify patients consuming medications and consider the possible implications.

REGISTRATION

PROSPERO (CRD42017078208).

Inhibitory Effects of 4-Hexylresorcinol on Root Resorption Induced by Orthodontic Tooth Movement

Root resorption during orthodontic tooth movement (OTM) is caused by an imbalance between the bone turnover rate and applied mechanical stress. The administration of 4-hexylresorcinol (4HR) increases the bone turnover rate and factors associated with bone formation. Thus, 4HR may show protective activity against root resorption during orthodontic tooth movement (OTM). A total of 40 rats (male: 20; female: 20) were included in this study, and the mandibular first molar was subjected to excessive orthodontic force. The experimental group (n = 20) received 12.8 mg/kg of 4HR every 2 weeks. The controls (n = 20) received a solvent without 4HR. Both groups had the same sex distribution. On Day 28 after the initiation of OTM, all the animals were sacrificed for micro-computed tomography analysis, Western blot analysis, and immunohistochemistry. The ratios of the root length and root volume to the total volume were significantly higher in the experimental group compared to those in the control group (p < 0.05). The expression levels of OPG, RANKL, alkaline phosphatase, and Runx2 in the experimental group according to Western blotting were significantly higher in the experimental group compared to those in the control group (p < 0.05). Their expression was mainly found in the periodontal ligament area. In conclusion, the administration of 4HR decreased the root resorption caused by OTM and increased the expression levels of OPG, RANKL, alkaline phosphatase, and Runx2.

Baicalin inhibits root resorption during tooth movement in a rodent model

OBJECTIVE

Baicalin mediates bone metabolism and has shown protective activity against periodontal tissue damage in a rat model of periodontitis. Therefore, we hypothesized that baicalin may inhibit the root resorption that occurs during orthodontic tooth movement and examined its effect on the histological changes in periodontal tissue that occur during tooth movement.

METHODS

First molars of rats were subjected to traction using excessive orthodontic force to produce a root resorption model. Rats in the baicalin group received baicalin for 3 weeks during tooth movement, and the amount of first molar movement on day 21 after the initiation of traction was measured by three-dimensional micro-computed tomography analysis. After tooth movement, tissue samples from the mesial and tension sides were collected, and successive horizontal sections were prepared and examined using hematoxylin-eosin and tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical staining for the receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG). The severity of root resorption was also determined by histological analysis.

RESULTS

There was no significant intergroup difference in tooth movement during the experimental exaggerated tooth movement. In comparison with the control group, the baicalin-treated group showed increased OPG expression, suppressed RANKL expression, and significantly fewer TRAP-positive cells in the first molars. The root resorption area was significantly smaller in the baicalin group.

CONCLUSIONS

Treatment with baicalin prevented root resorption without preventing tooth movement. Baicalin may be useful for the management of root resorption during orthodontic treatment.

Lithium chloride attenuates suppressed differentiation induced by mechanical strain in cementoblasts

Aim: The purpose of this study was to investigate the influence of mechanical strain on OCCM-30 cementoblast differentiation and Wnt/β-catenin pathway activity. Materials and Methods: Mechanical tension in the form of 2500-µ strain was applied to the cells using the Forcel four-point bending system, with or without the Wnt signaling activator, lithium chloride. Changes in cell differentiation and the expression of Wnt/β-catenin pathway components in response to strain and lithium chloride were assessed by real-time PCR, immunofluorescence, and western blotting. Results: The mRNA expression levels of the cementoblastogenesis-related genes alkaline phosphatase, runt-related transcription factor 2, and collagen 1, were decreased with mechanical strain. Similarly, the Wnt signaling pathway component genes LRP5, AXIN2, and LEF1 were decreased. The immunofluorescence assay demonstrated that scant β-catenin underwent nuclear translocation after the cells were subjected to mechanical strain. Moreover, western blotting showed that the protein levels of both β-catenin and phosphorylated β-catenin were increased after mechanical strain. In the presence of lithium chloride, the differentiation that was suppressed by mechanical strain was attenuated. Conclusions: 2500-µ strain mechanical strain inhibited cementoblast differentiation activity in vitro, which could be alleviated by actviating Wnt/β-catenin signaling using lithium chloride.

Effect of the software binning and averaging data during microcomputed tomography image acquisition

This study describes the effect of the software binning and data averaging during micro CT volume acquisition, on the assessment of root resorption volumes. The mesial roots (n = 9), after orthodontic tooth movement during 14 days, were scanned, using a micro CT system (9 µm/pixel). All roots were reconstructed and the volumes of the resorption lacunae evaluated. The height and width of the pixels vary according to the parameters (A1, A2, A3, A4, A5, A6, A7, A8, A9) used during the scan. In the root #1 the mean volumes of resorption were similar in A4 and A7; in the root #2 there was no similarity in the mean volumes of resorption in any of the parameters; in root #3 only A4 presented mean volume different from zero (3.05 × 10°). In the root #5, the A1 and A7 presented similar mean volumes and in the A6 and A9 presented near mean volumes. In the root #9 the A1, A4, and A7 presented similar mean volumes and A6 and A9 also had similar mean volumes. Significant difference was detected in the volume of resorption among the roots #2, #5 and #9 (p = 0.04). When analyzing delicate structures such as the roots of rats’ molars, the variation of such parameters will significantly influence the results.