Root Resorption Process Research Articles

The role of infection in signalling root resorption: Anarrative review.

Root resorption consists of complex, multistep processes that involve cell signalling caused by inflammation and stromal cells, which promotes the secretion of receptor activator of nuclear factor κB ligand/ macrophage-colony stimulating factor (RANKL/M-CSF) resulting in a resorptive process. The aim of this narrative review was to analyse the literature related to root resorption resulting from microbial infection and to comparing it with non-microbial infection. An electronic literature search was performed using the PubMed database and applying keywords of articles published in English. Eligible papers were reviewed to reveal the descriptions of bone and root resorption processes. The abstracts were searched manually to identify articles about infection-stimulating bone and root resorption. Three main types of root resorption were identified, two associated with primary bacterial infection and one secondary to bacterial infection. These include external inflammatory resorption, internal inflammatory resorption and external cervical (invasive) resorption. The magnitude of cytokine involvement that promotes resorption and M-CSF/RANKL production depends on multiple factors, including pathogen virulence, site of infection and host genetic factors that activate the inflammation at the infection site. Two mechanisms activate the resorption mechanisms-the canonical and non-canonical pathways that can activate clastic cells independently of the RANKL/RANK canonical pathways. Two pathways of root resorption co-exist in the body. When resorption is caused by infection, chronic inflammation due to bacterial infection prolongs the secretions of pro-inflammatory cytokines that intensify root and bone resorption. The second pathway is bacterial independent of the non-infection root resorption that is part of the wound healing process, which is limited in time due to its innate ability.

Interplay between dental pulp tissue osteoprotegerin and TNF-α levels with micromorphological changes in the teeth of patients with chronic pulpitis

Background/Aim. Chronic pulpitis (CP) is an inflammatory dental pulp disorder associated with various pathophysiological mechanisms in its origin. The aim of the study was to evaluate the changes in the pulp tissue of osteoprotegerin (OPG) and tumor necrosis factor (TNF)-? and establish their relationship with the histological changes of pulp tissue, as well as with the micromorphological changes, occurring in the mineralized tissue. Methods. The study examined the dental pulp of 41 patients with CP and 12 healthy individuals. The group of the diseased subjects was subdivided based on the presence of communication of the pulp with the oral cavity, i.e., open (n = 22) or closed (clausa) (n = 19) CP. Results. The levels of TNF-? were statistically significantly increased, while OPG levels were decreased in the pulp of patients with CP, compared to the control group. TNF-? levels were almost the same in the pulp of patients with closed CP and the control group, while values were significantly increased in those with open CP compared to control. Histopathological analysis showed a significant increase in the number of mononuclear inflammatory cells in the diseased pulp. Scanning electron microscopy showed distinct changes, which correlate with internal resorption. Conclusion. The results indicate a much greater and intensified process of root resorption in patients with closed CP, which is unassociated with dental pulp OPG and TNF-? level changes.

Quantitative Assessment of Dentine Sialophosphoprotein, Aspartate Aminotransferase and Lactate Dehydrogenase in Gingival Crevicular Fluid of Teeth with Root Resorption

Root resorption is a shortening of root dentine which occurs physiologically in deciduous teeth. The present study aimed to quantify dentine sialophosphoprotein (DSPP), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) in gingival crevicular fluid (GCF) during the physiological process of root resorption of deciduous teeth. A cross-sectional study was conducted with 25 children aged between 4 and 10 years old. GCF was collected from the gingival sulcus using periopaper strips from the upper first deciduous molar (n = 45). The samples were divided equally into three groups, no resorption (R0), moderate resorption (RM) and severe resorption (RS), based on the existing radiographs taken. The GCF samples were then analysed using an enzyme-linked immunosorbent assay (ELISA) kit to determine the DSPP concentration levels and BioAssays System kit for AST and LDH. One-way ANOVA was used to determine the statistical differences between the means of the DSPP, AST and LDH concentration level in the three groups. A difference was considered significant when p < 0.05. High concentration levels of DSPP were significantly noted in RS (p < 0.05), compared to RM and R0. AST also portrayed significant high activity level (p < 0.05) similar to DSPP but LDH showed no significant changes between groups (p > 0.05). The high quantification of DSPP and AST levels in the severe and moderately resorbed roots indicated the potential use of this protein as a biomarker for detecting moderate-severe stages of root resorption.

Detection of oral biomarkers as a diagnostic tool for orthodontically induced inflammatory root resorption: a literature review

Orthodontically induced inflammatory root resorption (OIIRR) is one of the most common complications of orthodontic treatment. Historically, only radiographic methods were available, while offering ease of use and accessibility, many limitations exist. Problems of technique, standardization, limited points of view and radiation exposure remain. Resorption can only be detected after a significant portion of the root has been lost (60% to70% mineralized tissue). Moreover, these methods are static and cannot indicate if the process of root resorption has arrested or is ongoing. Recently, oral fluids have been used as a tool for the diagnosis and monitoring of oral and systemic diseases through the detection of biomarkers. The purpose of this review is to describe the scientific evidence related to the prevalence, etiology, the traditional diagnostic methods and the advances in the detection of oral biomarkers through molecular biology for this pathology.

Comparison of surface roughness of root cementum and orthodontically induced root resorption craters from high- and low-fluoridation areas: a 3D confocal microscopy study

BackgroundFluoride has a major role in strengthening the structure of enamel against acids. Despite differences between caries and root resorption processes, both events inherently involve acidic dissolution of dental tissues. The aim of the present study was to investigate the effects of water fluoridation levels on the surface roughness of root cementum and resorption craters. The findings provided more insight into the influence of fluoride on the surfaces of intact cementum surface and resorption craters.MethodsTwenty-eight orthodontic patients were recruited from two cities in Turkey, with high (≥ 2 ppm) and low (≤ 0.05 ppm) water fluoridation. These patients needed bilateral maxillary first premolar extraction as part of their orthodontic treatment and were allocated into two study groups (n = 14 in each group) based on water fluoridation exposure level: the high-fluoride group (HF) and low-fluoride group (LF). 150 g of buccal tipping forces was applied to all maxillary first premolar teeth for 12 weeks with a beta-titanium spring which was reactivated every 4 weeks. All maxillary premolars were removed at the end of the experiment for surface roughness assessment using three-dimensional confocal microscopy and the associated software. The buccal root surface and the largest buccal resorption crater were investigated.ResultsResorption craters were significantly rougher in LF group compared to HF group (p = 0.002). Craters were rougher than the intact root surfaces (p = 0.000). Cervical and apical regions were significantly rougher than the middle region (p = 0.000 and p = 0.024, respectively).ConclusionsHigher water fluoridation level of ≥ 2 ppm resulted in significantly smoother root resorption craters than low water fluoridation level of ≤ 0.05 ppm when the teeth were subjected to 150 g of buccal tipping force. Fluoride seems to have a protective role at the interface of root resorption, and further mineral or histological studies may shed light on the exact protective process against root resorption.

Immunohistochemistry of resorption and inflammation factors in the periodontal ligament of human deciduous teeth.

The understanding of the biological mechanisms involved in root resorption in deciduous teeth is important to the future development of preventive measures and treatments of this condition. The aim of the present study was to compare the expression and immunostaining of iNOS, MMP-9, OPG and RANKL in the periodontal ligament (PDL) of deciduous teeth with physiologic root resorption (GI), inflammatory pathological root resorption (GII) and permanent teeth (GIII), the negative control. Teeth in GI (n = 10), GII (n = 10) and (GIII) (n = 10) were submitted to immunohistochemical analysis to determine the expression of iNOS, MMP-9, OPG, and RANKL. The immunostaining was analysed by optical density. Statistical analysis included one-way ANOVA, followed by Student-Newman-Keuls post hoc test (p < 0.05). The results showed that iNOS, MMP-9 and RANKL expression in the PDL was higher in GII compared to GI and GIII (p < 0.05). Moreover, RANKL expression was higher in GI compared to GIII (p < 0.001), while OPG immunolabelling was lower in GII compared to GI and GIII (p < 0.001). The PDL of deciduous teeth bearing inflammatory processed exhibited upregulation of resorption-associated factors as well as enzymes related to tissue degradation which, in turn explains the exacerbation and greater susceptibility of those teeth to root resorption process.

Clinical and radiographic evaluation of caries depth, root resorption and furcation lesion in primary molars

Primary molars with furcation lesions have a negative impact on the child's quality of life. We determined the prevalence of furcation lesions and their influence on the root resorption process in primary molars. It is Cross-sectional study of patients aged 3 to 12 years that was apply a health questionnaire was applied and the teeth were submitted to physical examination using the International Caries Detection and Assessment System (ICDAS) and periapical radiography. Criteria for radiographic interpretation were established and assessments performed by three different specialists. The kappa coefficient measured interexaminer agreement and level of significance of 5% was adopted for all tests. The sample consisted of 26 patients and 50 primary molars. The second molar received ICDAS score 6 in 38.5% of the sample. The interexaminer agreement was almost perfect between the radiologist and pediatric dentist for caries depth on the mesial (K=0.97) and occlusal surface (K=0.97); In root resorption for mesial (K=0.89) and distal (K=0.93). The detection of furcation lesions was present in 42.3% of the sample; 50% of the teeth had at least 1/3 of the mesial root resorbed and 75% of the distal root and the presence of furcation lesions in primary molars influenced root resorption.

Microcracks on the Rat Root Surface Induced by Orthodontic Force, Crack Extension Simulation, and Proteomics Study.

Root resorption is a common complication during orthodontic treatment. Microcracks occur on the root surface after an orthodontic force is applied and may be related to the root resorption caused by the orthodontic process. However, the mechanisms underlying root resorption induced by microcracks remain unclear. In this study, a rat orthodontic model was used to investigate the biological mechanisms of root resorption caused by microcracks. First, the first molar was loaded with 0.5-N orthodontic force for 7 days, and microcracks were observed on the root apex surface using a scanning electron microscope. Second, to describe the mechanical principle resulting in microcracks, a finite element model of rat orthodontics was established, which showed that a maximum stress on the root apex can cause microcrack extension. Third, after 7 days of loading in vivo, histological observation revealed that root resorption occurred in the stress concentration area and cementoclasts appeared in the resorption cavity. Finally, proteomics analysis of the root apex area, excluding the periodontal ligament, revealed that the NOX2, Aifm1, and MAPK signaling pathways were involved in the root resorption process. Microcrack extension on the root surface increases calcium ion concentrations, alters the proteins related to root resorption, and promotes cementoclast formation.

Influence of anti-allergic drugs used systemically on the process of root resorption during delayed tooth replantation: A study in rats.

Anti-allergic drugs can inhibit the hard tissue resorption process, and due to similarities between root resorption and bone mechanisms, it can be inferred that these drugs may also control root resorption. The aim of this study was to analyze the effects of anti-allergic drugs used systemically on the process of root resorption following delayed tooth replantation. Thirty-two maxillary right incisors of rats were extracted and subsequently replanted. Rats were divided into four groups according to the anti-allergic drug administered: the rats in groups DEX, Q, and MO were treated systemically with dexamethasone phosphate, quercetin, and montelukast, respectively, and no systemic medication was administered to rats in group C. After 60days, the animals were euthanized, and the specimens were processed for histomorphometric and immunohistochemical analyses. Statistical significance was set at P<.05. There were no significant differences between the groups in terms of inflammatory resorption, replacement resorption, or presence of tartrate-resistant acid phosphatase. In terms of events occurring in the periodontal ligament space, there was a difference between groups Q and MO due to the presence of dental ankylosis and inflammatory connective tissue (P<.05). A difference in inflammatory cells was also observed through CD45 immunolabeling between the DEX and Q groups when compared to the C group (P<.05). The systemic administration of anti-allergic drugs did not have an effect on the process of root resorption following delayed tooth replantation.

Biomarkers in the gingival crevicular fluid used to detect root resorption in patients undergoing orthodontic treatment: A systematic review.

To evaluate whether changes in the concentration of different biomarkers in the gingival crevicular fluid (GCF) can be used to detect the root resorption process in adult or adolescent patients undergoing treatment with a fixed appliance, in comparison with untreated subjects or treated patients not showing signs of root resorption. The following databases were analysed in the period between June 2017 and March 2018, without any language and initial date restrictions: PubMed, EMBASE, Scopus, Web of Science and Cochrane Library. A quality assessment instrument (QAI) was developed to establish the risk of bias. A total of 1127 articles were analysed. Based on the inclusion and exclusion criteria, seven studies qualified for the final review. The QAI tool revealed that five articles were at a moderate risk of bias and two articles were at a low risk of bias. Dentine phosphoprotein (DPP) may be considered a relatively useful marker for root resorption. Dentinal sialoprotein (DSP) could be a potential biomarker but is not highly helpful at detecting root shortening. Inflammatory cytokines (pro- and anti-resorption), osteopontin (OPN), osteoprotegerin (OPG), RANKL and alkaline phosphatase (ALP) are useful biomarkers to explain the biological mechanisms that occur during orthodontic movement but are not specific enough. Further studies are required to clarify the role of GM-CSF as a potential biomarker to distinguish subjects at a risk of severe root resorption in the early phase.

The Effect of local injection of strontium on inhibition and repair of orthodontically induced root resorption in rats (An experimental study)

Background: Strontium (Sr) is an alkaline earth trace metal cation that has a highaffinity for hydroxyapatite. This study aimed to examine the histological effect oflocally injected strontium (Sr) on prevention and repair of induced root resorptionof rat molar subjected to orthodontic tooth movement.Materials and Methods: Eighteen ten-week- old male Wister rats were randomlydivided into two groups of nine animals for two experiments. In both experiments;uniform standardized expansive springs were used to move maxillary first molarsbuccally for three weeks and then removed. In experiment No.1, at the time ofspring placement, 0.25 ml of the strontium chloride solution at a concentration 240mg/ml was injected at the sub-periosteum of the buccal side of the maxillary leftfirst molar which was the experimental side. On other hand, 0.25 ml of distilledwater was injected at the sub-periosteum of the buccal side of the right maxillaryfirst molar which was the control side. The injections repeated every other day forthree weeks whereas in experiment 2 it was begun at the day of spring removal andrepeated every other day for another three weeks. After that the animals werescarified humanly and biopsies were taken for histological examination.Results: In experiment 1 the side injected with strontium showed statisticallysignificant lesser root resorption than control side, while in experiment two thestrontium injected side showed significantly more repair.Conclusion: Results of the study suggested that local injection of strontium caninhibit root resorption process and enhance repair.

Root Resorption with Orthodontic Mechanics: Pertinent Areas Revisited.

Root resorption can occur at any time during orthodontic treatment and lead to a compromise in the prognosis of the tooth and the stability of the treatment results. Recent research has focused more on the cause and effect relationship as well as preventive or treatment options to combat this unwelcome event. Investigations have highlighted the genetic as well as molecular aspects of the process and enabled clinicians to determine which patients might be susceptible. A proper medical history, an assessment of predisposing factors, a radiographic evaluation for alterations in root morphology and careful planning and execution of orthodontic mechanics may reduce the incidence of root resorption. The current review is aimed at providing clinicians and academics with an insight into the process of root resorption, the methods of identification during its early stages and intervention at the right time to reduce its severity.

Root Resorption in Orthodontics: A Recent Update

Recently due to medico-legal factors, once again a lot of interest has been generated about the root resorption which is followed by orthodontic treatment. Newer information's are being continuously added and therefore process of root resorption have been better identified and understood.

EVALUATION OF ROOT RESORPTION FOLLOWING FORMCRESOL PULPOTOMY IN PRIMARY MOLARS

Aim: This study has been implemented in order that the prevalence and pattern of root resorption in mandibular primary molars previously treated with formcresol pulpotomy could be assessed compared with that takes place in apparently sound contralateral teeth.Subject and methods: The current retrospective cross sectional study has been fulfilled on a sample of 270 periapical radiographs of 118 children (55 females and 63 males) who have been treated at Pediatric Dentistry Department, at the Faculty of Dentistry, Cairo University. All radiographs were screned based on the method presented by Moorrees et al. for purpose of evaluating the process of root resorption . The root resorption process was divided into 5 stages.Results : It was shown by the results of study that no difference among root resorption between treated and non-treated teeth existed in most of the cases (91 cases). Whereas, accelerated and delayed root resorption were presented by 36 and 8 of cases, consecutively. Conclusion: It was concluded through investigation in this study that the prevalence of abnormal root resorption in the mandibular primary molars that was previously treated with formcresol pulpotomy was 32.6 %.

Notch Signaling Induces Root Resorption via RANKL and IL-6 from hPDL Cells

In this study, we first investigated the expressions of Jagged1, Notch2, the receptor activator of nuclear factor–kappa B ligand (RANKL), and interleukin (IL)-6 in areas of root resorption during experimental tooth movement in rats in vivo. We then assessed the effects of compression force (CF) with or without GSI (an inhibitor of Notch signaling) on Jagged1, RANKL, and IL-6 release from human periodontal ligament (hPDL) cells. Twelve male 6-wk-old Wistar rats were subjected to an orthodontic force of 50 g to induce mesially tipping movement of the upper first molars for 7 d. The expression levels of tartrate-resistant acid phosphatase, Jagged1, Notch2, IL-6, and RANKL proteins in the dental root were determined using an immunohistochemical analysis. Furthermore, the effects of the CF on Jagged1, IL-6, and RANKL production were investigated using hPDL cells in vitro. The effects of the cell-conditioned medium obtained from the hPDL cells subjected to CF (CFM) and Jagged 1 on osteoclastogenesis of human osteoclast precursor cells (hOCPs) were also investigated. Under the conditions of experimental tooth movement in vivo, resorption lacunae with multinucleated cells were observed in the 50 g group. In addition, immunoreactivity for Jagged1, Notch2, IL-6, and RANKL was detected on day 7 in the PDL tissue subjected to the orthodontic force. In the in vitro study, the compression force increased the production of Jagged1, IL-6, and RANKL from the hPDL cells, whereas treatment with GSI inhibited the production of these factors in vitro. The osteoclastogenesis increased with the CFM and rhJagged1, and the increase in the osteoclastogenesis was almost inhibited by GSI. These results suggest that the Notch signaling response to excessive orthodontic forces stimulates the process of root resorption via RANKL and IL-6 production from hPDL cells.

The Effect on Proliferation and Differentiation of Cementoblast by Using Sclerostin as Inhibitor

Cementogenesis is of great importance for normal teeth root development and is involved in the repair process of root resorption caused by orthodontic treatment. As highly differentiated mesenchymal cells, cementoblasts are responsible for this process under the regulation of many endogenous agents. Among these molecules, sclerostin has been much investigated recently for its distinct antagonism effect on bone metabolism. Encoded by the sost gene, sclerostin is expressed in osteocytes and cementocytes of cellular cementum. it is still unclear. In the current study, we investigated the effects of sclerostin on the processes of proliferation and differentiation; a series of experiments including MTT, apoptosis examination, alkaline phosphatase (ALP) activity, gene analysis, and alizarin red staining were carried out to evaluate the proliferation and differentiation of cementoblasts. Protein expression including osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) were also checked to analyze changes in osteoclastogenesis. Results show that sclerostin inhibits cementoblasts proliferation and differentiation, and promotes osteoclastogenesis. Interestingly, the monoclonal antibody for sclerostin has shown positive effects on osteoporosis, indicating that it may facilitate cementogenesis and benefit the treatment of cementum related diseases.

Deciduous dental pulp stem cells are involved in osteoclastogenesis during physiologic root resorption

Multipotent mesenchymal stem cells are derived from the dental pulps of permanent teeth and exfoliated deciduous teeth, and are known to induce bone and dentin generation. However, the role of deciduous dental pulp stem cells (DDPSCs) in physiologic root resorption remains unclear. In this study, dental pulp stem cells (DPSCs) in permanent teeth (P) were retrieved and compared to DDPSCs from deciduous incisors at different root resorption stages: stable (S), middle (M), and final (F). Decalcified teeth sections showed that osteoclasts and resorption lacunae were most prevalent in the M resorption stage. DDPSC proliferation rate was also highest in the M stage. DDPSCs in the F stage produced more calcified nodules than those in the S or M stages. Alkaline phosphatase (ALP) expression was highest in the F stage, indicating that DDPSCs promote mineralization. In addition, the ratio of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) expression was significantly higher in the M stage, indicating that DDPSCs promote resorption. Dickkopf 1 (Dkk1) expression was remarkably higher in the F and P groups, suggesting that the Wnt pathway is inhibited during the resorption process. Interestingly, despite the fact that Wnt3a down-regulated OPG in osteogenic induction medium and up-regulated RANKL in medium with 1,25-dihydroxy vitamin D3 (VD(3) ), the RANKL/OPG ratio was reduced only with VD(3) . Collectively, our data indicate that DDPSCs influence osteoclastogenesis during the physiologic root resorption process, and that the canonical Wnt pathway can change the RANKL/OPG expression ratio in DDPSCs.

A Histopathological Comparison of Pulpal Response to Chitra-CPC and Formocresol used as Pulpotomy Agents in Primary Teeth: A Clinical Trial.

ABSTRACTPreventive measures have helped to minimize the occurrence of dental caries. However, premature loss of primary teeth on account of dental caries still remains a common problem among children. The pulpotomy technique has been the choice for treating vital primary and young permanent teeth with carious, mechanical and traumatic pulp exposures. The ideal pulpotomy medicament should be bioinductive or at least biocompatible, bactericidal and harmless to the pulp and surrounding structures. It should also promote healing of the radicular pulp and prevent bacterial microleakage with the least interference in the physiological process of root resorption. Since the best criteria for judging the effectiveness of a medicament when used for vital pulp therapy is the response that it produces in the pulp. The purpose of the present study was to evaluate and compare the response of human pulp tissue to recently developed Indian material, Sree Chitra-Calcium Phosphate Cement (Chitra-CPC) and formocresol, used as pulpotomy agent in deciduous teeth. Chitra-CPC has been compared with formocresol, taking into account that formocresol is still considered the gold standard in primary tooth pulpotomy. The study was conducted among 10 children in the age group of 8 to 12 years focusing on 20 noncarious primary canines indicated for serial extraction. Each patient received two different pulpotomy procedures—one in each of the primary canines using formocresol and the other with Chitra-CPC as pulpotomy agents. After 70 days, the teeth were extracted and subjected to histological examination. The results did not reveal statistically significant difference between the two groups. But Chitra-CPC gave more favorable results, in respect of pulpal inflammation, dentin bridge formation, quality of dentin bridge and connective tissue in dentin bridge.How to cite this article: Ratnakumari N, Thomas B. A Histopathological Comparison of Pulpal Response to Chitra- CPC and Formocresol used as Pulpotomy Agents in Primary Teeth: A Clinical Trial. Int J Clin Pediatr Dent 2012;5(1):6-13.

The Isolation of Stem Cells from Human Deciduous Teeth Pulp Is Related to the Physiological Process of Resorption

Introduction The aim of this study was to isolate and grow cells from sound human deciduous teeth pulp with different levels of resorption and evaluate stem cell parameters. Methods Pulp tissue was removed from 30 different patients, aged from 6 to 12 years. From all the teeth, 21 were in advanced levels of resorption (group 1), and the remaining nine teeth did not show any visible resorption (group 2). Pulp tissue was removed and dissociated, and the suspension was seeded onto 12-well plates. The phenotype of the cells (n = 5) was analyzed on fifth and tenth passages by flow cytometry for clusters of differentiation (CD)29/PE, CD34/PE, CD44/FITC, CD45/FITC, CD90/FITC, CD117/PE, CD133/PE, CD146/FITC, CD184/PE, Stromal Cell Surface Marker 1 (STRO-1)/FITC and human leukocyte antigen major histocompatibility complex class II surface receptor (HLA-DR)/FITC, and by reverse transcription–polymerase chain reaction (RT-PCR) for octamer-binding transcription factor 4 (OCT-4). On the same passages, cells were differentiated into adipocytes, osteoblasts, and chondrocytes. Results Cell isolation was successful in 25 samples, but only 17 of these reached 90% confluence. It was not possible to establish cell culture from group 2. Cells on both fifth and tenth passages were positive for CD29, CD44, and CD90 and also for the expression of OCT-4. Moderate labeling was observed for CD117 and CD133, whereas a low expression was detected for CD34, CD45, HLA-DR, CD184, CD146, and STRO-1. All cultures differentiated into three cell types. Conclusions The isolated pulp cells can be considered stem cells. The facility for obtaining cells seems to be related to the root resorption process, so, therefore, the cells from group 1 were able to proliferate in vitro, whereas group 2 cells were not.

IL‐8 and MCP‐1 induced by excessive orthodontic force mediates odontoclastogenesis in periodontal tissues

The aim of this study was to investigate how interleukin (IL)-8 (cytokine-induced neutrophil chemoattractant; CINC-1) and monocyte chemotactic protein (MCP)-1/CCL2 contribute to root resorption during orthodontic tooth movement. Forty 6-week-old male Wistar rats were subjected to orthodontic force of 10 or 50 g to induce a mesially tipping movement of the upper first molars for 7 days. We determined the expressions of CINC-1, CXCR2, and MCP-1 proteins in root resorption area using immunohistochemistry. Furthermore, we investigated the effects of compression forces (CF) on IL-8 and MCP-1 production by human periodontal ligament (hPDL) cells. We observed an effect of chemokine treatment on rat odonto/osteoclasts in dentin slices that recapitulated root resorption. The immunoreactivity for CINC-1/CXCR2 and MCP-1 was detected in odontoclasts and PDL fibroblasts by the orthodontic force of 50 g on day 7. CF increased the secretion and the expression of mRNA of IL-8 and MCP-1 from PDL cells in a magnitude-dependent manner. Moreover, CINC-1 and MCP-1 stimulated osteoclastogenesis from rat osteoclast precursor cells. IL-8 (CINC-1) and MCP-1 may therefore facilitate the process of root resorption because of excessive orthodontic force.