A study of interleukin 1β levels in peri-miniscrew crevicular fluid (PMCF)

Oral Fluid Biomarkers for Peri-Implantitis: A Scoping Review

Peri-implantitis, a prevalent complication in dental implant therapy, poses a significant threat to long-term implant success. The identification of reliable biomarkers for the early detection and monitoring of peri-implantitis is crucial for timely intervention and improved treatment outcomes. Salivary and peri-implant sulcular fluid (PISF) biomarkers have become promising diagnostic tools in the field of implant dentistry. This scoping review aims to explore current studies in the literature on salivary and PISF biomarkers for peri-implantitis. A systematic search was conducted on 2 databases (PubMed and Scopus) to identify relevant studies published up to January 2023. A total of 86 articles were included, which underwent data extraction and analysis. Several biomarkers have been investigated in salivary and PISF samples for association with peri-implantitis. Investigations included a wide range of biomarkers, including inflammatory markers, matrix metalloproteinases and bone loss markers. The findings suggested that certain salivary and PISF biomarkers demonstrated potential in distinguishing healthy peri-implant conditions from peri-implantitis. Elevated levels of proinflammatory cytokines, such as interleukin-1β (IL-1β) and interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), and matrix metalloproteinases, have been consistently associated with peri-implantitis. Additionally, alterations in bone loss markers have shown potential as indicators of disease progression and treatment response. In conclusion, this scoping review provides an overview of current knowledge on salivary and PISF biomarkers for peri-implantitis. The identified biomarkers are promising as noninvasive diagnostic tools for early detection, monitoring, and personalised management of peri-implantitis. Future studies should focus on establishing standardised protocols and conducting well-designed clinical trials to validate the diagnostic accuracy and clinical relevance of these biomarkers.

Quantitative Evaluation of Pentraxin-3 in Peri-Miniscrew Implant Crevicular Fluid in Patients Undergoing Orthodontic Treatment: A Prospective Study

OBJECTIVE

To assess the levels of Pentraxin-3 (PTX3) in peri-miniscrew implant crevicular fluid (PMICF) before and after orthodontic force application Material and Methods: This study included 40 miniscrew implants (MSI) sites in 11 orthodontic patients with high arch discrepancy requiring first premolar extraction using maximum anchorage mechanics for the retraction of anterior teeth. After alignment, the en-masse anterior retraction was carried out using the MSI-supported direct anchorage method. PMICF was collected from the crevice of MSI using Periopaper strips 1.2µl (Oraflow Inc. USA) after one hour, 24 hours, and three weeks of MSI insertion and after one hour, 24 hours, seven days, three weeks, and six weeks of the force application. Samples were quantitatively analyzed for PTX3 levels through enzyme-linked immunosorbent assay (ELISA).

RESULTS

The trend in the change of PTX3 levels was evaluated using the Wilcoxon signed-rank test. The mean concentration of PTX3 immediately after MSI insertion was 1.19 ng/ml, significantly higher than after 3 weeks after MSI insertion (0.72 ng/ml), which may correspond to the baseline. After loading, the mean PTX3 concentration increased significantly with the peak at 24 hrs (1.28 ng/ml), followed by a gradual decline till the completion of the study (0.5 ng/ml).

CONCLUSION

After MSI insertion, a rise in PTX3 levels in PMICF suggests an underlying inflammatory process. The slow decline in PTX3 level and return to the baseline after loading suggests an adaptive bone response to the stimulus.

A quantitative analysis of macrophage-colony-stimulating factor in peri-miniscrew implant crevicular fluid before and after orthodontic loading

OBJECTIVES

To analyze macrophage-colony-stimulating factor (M-CSF), a bone remodeling biomarker in the peri-miniscrew implant crevicular fluid (PMICF) after insertion and orthodontic loading.

MATERIALS AND METHODS

This prospective study included 40 miniscrew implant (MSI) sites in 10 subjects undergoing fixed orthodontic mechanotherapy utilizing miniscrew anchorage. After dental alignment, miniscrews were inserted between the second premolar and first molar roots. After 21 days of insertion, MSIs were direct loaded with closed-coil springs (200 g force) for en masse retraction of anterior teeth. PMICF was collected with Periopaper™ strips from the gingival crevice around MSIs at six time points (T1-T6: 1 hour, 1 day, 21 days postinsertion, and 7, 21, and 42 days postloading). PMICF was quantified for M-CSF by enzyme-linked immunosorbent assay. Paired comparison of mean M-CSF concentrations before and after loading stages (T1-T6) was made using the Wilcoxon signed-rank test.

RESULTS

The mean M-CSF concentration showed a significant peak at T3 (21 days postinsertion; 12.646 pg/mL; T1 vs T3: P < .0001). After orthodontic loading of miniscrews, M-CSF levels increased to 13.570 pg/mL at T4 (7 days after loading; T1 vs T4: P < .001) and maintained at a plateau to T5 (21 days postloading; 11.994 pg/mL). However, the difference between preloading and postloading was not statistically significant (T3 vs T4).

CONCLUSIONS

The maximum M-CSF activity around MSIs was observed at around 3 weeks of miniscrew insertion, suggesting underlying bone remodeling after surgical injury. However, orthodontic force on MSIs did not cause any significant surge in M-CSF levels postloading.

Comparison of interleukin expression in gingival crevicular fluid between patients with invisible orthodontics treat-ment and fixed orthodontics treatment

OBJECTIVES

To compare the expression levels of interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-16, and IL-18 in gingival crevicular fluid between patients with invisible orthodontics treatment and fixed orthodontics treatment.

METHODS

A total of 67 patients with invisible orthodontic treatment were selected as the observation group, and 40 patients with fixed orthodontic treatment were selected as the control group. The expression levels of IL-1β, IL-6, IL-8, IL-10, IL-16, and IL-18 in gingival crevicular fluid before, 24 h, and 12 months after orthodontic treatment were detected.

RESULTS

No significant difference in basic characteristics and interleukin expression levels in gingival crevicular fluid was observed between the two groups before orthodontic treatment (P>0.05). After 24 h of orthodontic treatment, the expression levels of IL-1β, IL-6, IL-8, IL-10, and IL-18 in gingival crevicular fluid increased in both groups; however, no significant difference was observed between the two groups (P>0.05). After 12 months of orthodontic treatment, the expression levels of IL-1β, IL-6, IL-8, IL-10, and IL-18 in gingival crevicular fluid in the observation group were significantly lower than those in the control group (P<0.05), and no significant difference in the expression level of IL-16 was observed between the two groups (P>0.05).

CONCLUSIONS

Compared with patients with fixed orthodontics treatment, those with invisible orthodontics treatment had weaker oral inflammatory response, which was conducive to the recovery of the oral microenvironment.

Orthodontics Surgical Assistance (Piezosurgery®): Experimental Evidence According to Clinical Results

Orthodontic tooth movement (OTM) is based on intermitted or continuous forces applied to teeth, changing the mechanical loading of the system and arousing a cellular response that leads to bone adaptation. The traditional orthodontic movement causes a remodeling of the alveolar bone and changes in the periodontal structures that lead to tooth movement. The use of a piezoelectric instrument in orthodontic surgery has already shown great advantages. The purpose of this study is to rank the behavior of inflammatory mediators in accelerating orthodontic tooth movement. Ten patients with malocclusion underwent orthodontic surgical treatment, which included a first stage of surgically guided orthodontic movement (monocortical tooth dislocation and ligament distraction, MTDLD) to accelerate orthodontic movements. In all cases, corticotomy was performed by Piezosurgery. Bone and dental biopsy was executed to evaluate changes in the cytokines IL-1beta, TNF-alpha and IL-2 in different time intervals (1, 2, 7, 14 and 28 days). The molecular mediators are IL-1 beta, TNF-alpha and IL-2. Immediately after the surgical procedure there was a mild expression of the three molecular markers, while the assertion of IL-1 beta and TNF-alpha reached the maximum value after 24 h and 48 h, indicating a strong activation of the treated tissues. The Piezosurgery® surgical technique induces an evident stress in short times, within 24–48 h from the treatment, but it decreases significantly during the follow-up.

Expression of circulating cell-free nucleic acids around miniscrew implant during orthodontic tooth movement-a prospective study

OBJECTIVES

Literature shows that the expression of various biomarkers in peri-miniscrew crevicular fluid (PMICF) is related to the stability of miniscrew implants (MSIs). The present study investigated the role and alterations in levels of circulating cell-free nucleic acids (cfNAs) in PMICF before and after orthodontic loading.

MATERIAL AND METHODS

This prospective study consisted of forty-six MSIs placed between the second premolar and first molar in the maxillary and mandibular arches. Direct loading was done after 3 weeks of MSI insertion with nickel-titanium closed coil spring exerting a force of 200 g. The PMICF sample was collected at various time intervals, and the level of cfNA was determined. Clinical parameters, including implant mobility and gingival health, were also assessed. Pre-loading and post-loading parameters were assessed using Wilcoxon's rank-sum test.

RESULTS

Among 46 MSIs, 36 were stable during the study and 10 MSIs showed peri-implant inflammation and increased mobility. There was a significant rise in the cfNA concentration 24 h after implant insertion (0.4 ± 0.86 ng/μl). The level of cfNAs significantly decreased over 3 weeks and reached the baseline level (0.2 ± 0.31 ng/μl). There was also a significant rise in the levels of cfNA (0.8 ± 0.70 ng/μl) at 24 h after loading MSIs, which gradually decreased to 0.2 ± 0.24 ng/μl after 63 days. The expression of cfNAs was on the average 0.32 units more in the cases with failed implants (P = 0.05).

CONCLUSIONS

cfNA levels in PMICF showed an upward trend 24 h after MSI insertion and 24 h after orthodontic loading. The expression of cfNA was more in cases with failed MSIs. Hence, the cfNAs can be considered as a prognostic biomarker of MSI stability.

Comparison of the efficacy of two-time versus one-time micro-osteoperforation on maxillary canine retraction in orthodontic patients: A split-mouth randomized controlled clinical trial

BACKGROUND

Micro-osteoperforation (MOP), a minimally invasive technique for accelerating the rate of orthodontic tooth movement has been research extensively, but with varied clinical results.

OBJECTIVE

To compare the efficacy of one-time versus two-time micro-osteoperforation on the rate of maxillary canine retraction, its influence on anchorage loss, canine angulation and the levels of interleukin (IL-1β) in gingival crevicular fluid (GCF).

MATERIALS AND METHODS

The split-mouth study included 16 patients in which the left and right sides were randomly allocated to the control side (one-time MOP) and experimental side (two-time MOP). MOP was performed on both sides distal to the maxillary canines and canine retraction was carried out using NiTi closed coil springs (150gm) and direct anchorage with miniscrew implants. The second MOP was performed on experimental side one month after the first MOP. The rate of canine movement was assessed using 3D model superimposition over a period of six months. The type of tooth movement, anchorage loss and levels of IL-1β were also evaluated.

RESULTS

Sixteen patients (mean age, 17.87±3.34 years) were analysed for a rate of canine retraction, anchorage loss, and type of tooth movement, while 15 patients were analysed for IL-1β. The rate was significantly higher on two-time MOP side after two months (P<0.001). No statistical difference was found in anchorage loss and controlled tipping of canines was observed. The IL-1β levels immediately after 2^nd MOP were significantly higher than 1^st MOP (P<0.001).

CONCLUSION

The two-time intervention of MOP is more efficacious than one-time MOP in accelerating tooth movement.

Evaluation of heat shock protein 70 and toll-like receptor 4 expression in gingival crevicular fluid in response to orthodontic forces

OBJECTIVES

The aim of this study was to assess the concentrations of heat shock protein 70 (HSP70) and toll-like receptor 4 (TLR4) during orthodontic tooth movement and to compare their levels with interleukin-1β (IL-1β), a well-known proinflammatory biomarker.

MATERIALS AND METHODS

This study consisted of 20 patients (8 males, 12 females; mean age 14.75 ± 2.34 years) who needed maxillary premolar extraction and segmental canine distalization. Concentrations of HSP70, TLR4, and IL-1β were examined before extraction (T1), at the 1st (T2), 4th (T3), 7th (T4), 14th (T5), and 30th (T6) days of canine retraction by enzyme-linked immunosorbent assay analysis of gingival crevicular fluid samples. Statistical analyses were performed with repeated measure ANOVA and Spearman's rank correlation coefficient analysis (p < 0.05).

RESULTS

HSP70 increased gradually from T1 to T6 and showed significant differences between T1-T6 and T2-T6 (T1:3.28 ± 0.92 ng/ml; T2:3.72 ± 0.66 ng/ml; T6:9.35 ± 2.45 ng/ml). The lowest TLR4 concentration was at T1, peaked at T3 and remained constant afterwards with significant differences between T1-T3, T1-T4, and T1-T6 (T1:0.71 ± 0.02 pg/ml; T3:1.04 ± 0.11 pg/ml; T4:0.95 ± 0.06 pg/ml; T6:1.00 ± 0.07 pg/ml). IL-1β increased from T1 to T6 with significant differences between T1-T4, T1-T5, and T1-T6 (T1:55.71 ± 5.48 pg/ml; T4:100.11 ± 16.92 pg/ml; T5:103.71 ± 23.19 pg/ml; T6:125.12 ± 22.04 pg/ml). The increase in HSP70 and TLR4 from T2-T3 showed a significant correlation (r = 0.598; p = 0.005).

CONCLUSIONS

The increased levels of HSP70, TLR4, and IL-1β show the contribution of these mediators to the inflammatory response from the early stages of orthodontic tooth movement.

CLINICAL RELEVANCE

The regulation of HSP70, TLR4, and/or IL-1β secretion during orthodontic force application could provide alterations for desired optimal tooth movement.

Levels of TGF-β1 in peri-miniscrew implant crevicular fluid

The peri-miniscrew implant crevicular fluid is analogous to gingival crevicular fluid, and its contents reflect the state of inflammation and health during the life of the miniscrews in the mouth. The stability of MSI is fundamental to its role as an anchorage. This study aimed to evaluate transforming growth factor-beta one (TGF-β1) of the peri-miniscrew implant crevicular fluid (PMICF), on implant insertion, pre- and post-loading of MSIs to find a clue to their role in the stability of MSI. Fifty-two MSIs sites were placed in the mouths of 13 patients aged 12-26 years undergoing orthodontic treatment. PMICF was collected using micro-pipettes at T1 (day 0, 1 h after MSI implantation), T2 (day 1), T3/baseline (day 21, preloading of MSI), T4 (day 21, 1 h post loading), T5 (day 22, 1 day post loading), T6 (day 43, 3 weeks post loading). The levels of TGF-β1 were estimated by enzyme-linked immunosorbent assay (ELISA). The data were subjected to statistical analysis. Of the 52 MSIs, 20 MSIs failed at T3. In the case of successful MSIs, the TGF-β1 levels were found to monotonously decrease from T1 (~1400 pg/mL) until T3 (~700 pg/mL) and saturate thereafter. In the case of failed MSIs, the levels of TGF-β1 at various time periods were approximately constant and of much lower value than corresponding time periods of successful MSIs. This study highlights the role of TGF- β1 in bone metabolism around miniscrew reflecting the state of inflammation from 1 h post-implantation.

Effect of orthodontic forces on levels of enzymes in gingival crevicular fluid (GCF): A systematic review

Objective:

Orthodontic force application releases multiple enzymes in gingival crevicular fluid (GCF) for activation, resorption, reversal, deposition of osseous elements and extracellular matrix degradation. The current systematic review critically evaluated all existing evidence on enzymes in orthodontic tooth movement.

Methods:

Literature was searched with predetermined search strategy on electronic databases (PubMed, Scopus, Embase), along with hand search.

Results:

Initial search identified 652 studies, shortlisted to 52 studies based on PRISMA. Quality assessment further led to final inclusion of 48 studies (13 moderately and 35 highly sensitive studies). Primary outcomes are significant upregulation in GCF levels of enzymes-aspartate aminotransferase (AST), alkaline phosphatase (ALP), matrix metalloproteinases (MMPs), lactate dehydrogenase (LDH), β-glucuronidase (βG), tartrate resistant acid phosphatase (TRAP), acid phosphatase (ACP) and down regulation in cathepsin B (Cb). Site specificity is shown by ALP, TRAP, AST, LDH, MMP9 with levels at compression site increasing earlier and in higher quantities compared with tension site. ALP levels are higher at tension site only in retention. A positive correlation of LDH, ALP and AST is also observed with increasing orthodontic force magnitude.

Conclusions:

A strong evidence of variation in enzymes (ALP, AST, ACP TRAP, LDH, MMPs, Cb) in GCF is found in association with different magnitude, stages and sites of orthodontic force application.

Influence of orthodontic loading on biomarkers levels around miniscrews

OBJECTIVE

The aim of this study was to evaluate the levels of Interleukin-1α (IL-1α), Interleukin-1β (IL-1β), Interleukin-1 receptor antagonist (IL-1Ra), Interleukin-10 (IL-10), Interleukin-13 (IL-13), Vascular endothelial growth factor (VEGF), Granulocyte-colony stimulating factor (G-CSF), and Growth related oncogene (GRO) in the peri-miniscrew implant crevicular fluid (MICF) under orthodontic loading.

DESIGN

The study sample comprised 14 miniscrews immediately loaded and 17 unloaded ones. A load of 200gF was immediately applied to the miniscrews in the loaded group after the placement surgery. Peri-miniscrew implant crevicular fluid was collected at baseline, at day 7, and at day 21. The levels of the biomarkers were measured using a multiplexed bead immunoassay. Intergroup comparisons were made using Mann-Whitney test. Friedman and Dunn's multiple comparison tests were used to evaluate intragroup differences over time.

RESULTS

Although no statistical differences were observed between the groups at any time point for any of the 8 biomarkers evaluated, there was a statistically significant increase (p < 0.02) in the levels of all the biomarkers over time on both groups.

CONCLUSIONS

An immediate loading of 200gF does not alter the balance in the inflammatory response in peri-miniscrew tissues.

Comparison of BALP, CTX-I, and IL-4 levels around miniscrew implants during orthodontic tooth movement between two different amounts of force

OBJECTIVES

To evaluate the Interleukin-4 (IL-4), bone-specific alkaline phosphatase (BALP), and C-telopeptide of type I collagen (CTX-I) levels in peri-miniscrew crevicular fluid (PMCF) during orthodontic tooth movement between 75 and 150 g of distalization force.

MATERIALS AND METHODS

Thirty miniscrews were placed bilaterally between the maxillary second premolars and first molars. The right and the left maxillary canines were moved distally using either 75 or 150 g of force. PMCF samples were collected before loading (T0); at 2 hours (T1) and 24 hours (T2) later; and on days 7 (T3), 14 (T4), 21 (T5), 30 (T6), and 90 (T7) after force application. Enzyme-linked immunosorbent assay kits were used to determine BALP, CTX-I, and IL-4 levels.

RESULTS

There was no significant difference between the force groups at all time points with respect to BALP, CTX-I, and IL-4 levels (P > .05). There was no significant difference among time points for the two force groups in terms of BALP and IL-4 levels (P > .05). The CTX-I level at T3 was significantly higher than at T0 for both force groups (P < .05).

CONCLUSIONS

Both 75 g and 150 g of orthodontic force are within optimal force limits, and there is no difference in biochemical markers of bone turnover.

Extra-Alveolar Bone Screws for Conservative Correction of Severe Malocclusion Without Extractions or Orthognathic Surgery

PURPOSE OF REVIEW

Evaluate management of challenging malocclusions conservatively (no extractions or orthognathic surgery).

RECENT FINDINGS

Most malocclusions have a predominately environmental etiology. Optimal esthetics and function are restored by aligning the dentition over the apical base of bone at the appropriate vertical dimension of occlusion (VDO). Extra-alveolar (E-A) anchorage is achieved at three intraoral sites: mandibular buccal shelf (MBS), infrazygomatic crest (IZC), and anterior ramus. MBS and IZC bone screws effectively anchor the conservative correction of severe dental and skeletal malocclusions. All bone screw sites are effective for anchoring lever arms to recover impacted teeth. Rather than extracting teeth, E-A anchorage corrects crowding by retracting the posterior segments to increase arch length. Skeletal malocclusion is corrected by aligning teeth over the apical base of bone and restoring the VDO by retracting and posteriorly rotating the dental arches as segments. Challenging dental and skeletal malocclusions can be treated routinely via determinate mechanics anchored with E-A bone screws.

A review of biomarkers in peri-miniscrew implant crevicular fluid (PMICF)

Background

The temporary anchorage devices (TADs) which include miniscrew implants (MSIs) have evolved as useful armamentarium in the management of severe malocclusions and assist in complex tooth movements. Although a multitude of factors is responsible for the primary and secondary stability of miniscrew implants, contemporary research highlights the importance of biological interface of MSI with bone and soft tissue in augmenting the success of implants.

The inflammation and remodeling associated with MSI insertion or loading are reflected through biomarkers in peri-miniscrew implant crevicular fluid (PMICF) which is analogous to the gingival crevicular fluid. Analysis of biomarkers in PMICF provides indicators of inflammation at the implant site, osteoclast differentiation and activation, bone resorption activity and bone turnover. The PMICF for assessment of these biomarkers can be collected non-invasively via paper strips, periopaper or micro capillary pipettes and analysed by enzyme-linked immunosorbent assay (ELISA) or immunoassays. The markers and mediators of inflammation have been previously studied in relation to orthodontic tooth movement include interleukins (IL-1β, IL-2, IL-6 and IL-8), growth factors and other proteins like tumour necrosis factor (TNF-α), receptor activator of nuclear factor kappa-B ligand (RANKL), chondroitin sulphate (CS) and osteoprotegerin (OPG).

Studies have indicated that successful and failed MSIs have different concentrations of biomarkers in PMICF. However, there is a lack of comprehensive information on this aspect of MSIs. Therefore, a detailed review was conducted on the subject.

Results

A literature search revealed six relevant studies: two on IL-1β; one on IL-2, IL-6 and IL-8; one on TNF-α; one on CS; and one on RANKL/OPG ratio. One study showed an increase in IL-1β levels upon MSI loading, peak in 24 hours (h), followed by a decrease in 21 days to reach baseline in 300 days. A 6.87% decrease in IL-2 levels was seen before loading and a 5.97% increase post-loading. IL-8 showed a 6.31% increase after loading and IL-6 increased by 3.08% before MSI loading and 15.06% after loading. RANKL/OPG ratio increased in loaded compared to unloaded MSIs.

Conclusions

Cytokines (mainly ILs and TNF-α) and RANKL/OPG ratio showed alteration in PMICF levels upon loading of MSIs as direct or indirect anchorage.

Effects of Low-Level Laser Therapy in Orthodontic Patients on Immediate Inflammatory Response After Mini-Implants Insertion: A Preliminary Report

BACKGROUND

The primary stability of a mini-implant is crucial to treatment sequence since most orthodontic mini-implant failures occur at an early stage. Irritation or inflammation of peri-implant tissues has been related to decreasing mini-implant success.

PURPOSE

This study evaluates the effect of low-level laser therapy on initial inflammation after orthodontic mini-implants installation.

METHODS

Ten volunteers received two mini-implants (1.3 mm diameter, 7 mm length). One mini-implant was inserted on each side of the maxilla following manufacturer recommendation. On the right side, low-level laser therapy (LLLT) was applied (diode laser 660 nm, 40 mW, 1 min, 2.4 J of total energy). Peri-implant crevicular fluid (PGF) was obtained after 24 h (T1), 48 h (T2), and 72 h (T3) to identify levels of interleukin (IL)-6 and IL-8 around mini-implants and around upper first premolars.

RESULTS

An increase in interleukin levels was observed for both groups, compared to upper first premolar. PGF around nonirradiated mini-implants showed higher levels of IL-8. Levels of IL-6 24 h after mini-implant insertion were higher for laser group.

CONCLUSIONS

LLLT modulates the initial inflammation after the insertion of mini-implant, possibly increasing the mini-implant success prognostic and decreasing patient discomfort.

Effect of orthodontic forces on cytokine and receptor levels in gingival crevicular fluid: a systematic review

This systematic review aimed to generate evidence on role of potent markers of inflammation [cytokines, chemokines, their associated receptors and antagonists] following the application of orthodontic forces. Subsequent to registration with PROSPERO, literature search followed a predetermined search strategy to key databases along with hand search (HS). Seventy-seven articles from PubMed (P), 637 from Scopus (S), 51 from Embase (E), and 3 from hand search (HS) were identified. A total of 39 articles were shortlisted that met strict inclusion and exclusion criteria and quality assessment. Each study was evaluated for participant characteristics, study design, oral hygiene regimen, and gingival crevicular fluid (GCF) handling. Among these studies, biomarkers in the order of frequency were interleukin (IL)-1β (N = 21), tumor necrosis factor (TNF)-α (N = 10), IL-8,IL-6(N=8), receptor activator of nuclear factor kappa-B ligand (RANKL) (N = 7), monocyte chemoattractant protein (MCP)-1 (N = 3), IL-2 (N=4), IL-4, IL-10, RANTES (N = 2), IL-1, IL-5, IL-1α, IP-10, osteopontin (OPN) (N = 1) and receptors and their antagonists in the order of osteoprotegerin (OPG) (N = 8), IL-1RA (N = 5), and RANK (N = 1). Results revealed an immediate release of inflammatory bone-resorptive mediators, IL-1β and TNF-α, where IL-1β increased as early as 1 min to 1 h reaching peak at 24 h while TNF-α increased at 1 h or 1 day. This was accompanied by a fall in bone-protective mediator (OPG) levels at 1 h and 24 h after orthodontic force application. Continuous forces were accompanied by a decrease in mediator levels after attaining peak levels (most commonly at 24 h) while repeated activations in interrupted force upregulated their secretion. Significant correlations of IL-1β levels with pain intensity, rate of orthodontic tooth movement (OTM) and of activity index (AI) (IL-1β/IL-1RA) with velocity of tooth movement and growth status of individuals have also been deduced. A greater AI and RANKL/OPG ratio was seen in juveniles as compared to adults or non-growers that were associated with faster rate of OTM in juveniles. None of the studies addressed the effect of estrous cycle in female subjects. Lack of homogeneity in several parameters calls for a better controlled research on the biology of OTM.