Phase Of Orthodontic Tooth Movement Research Articles

Differential gene expression and protein-protein interaction networks of human periodontal ligament stromal cells under mechanical tension

Orthodontic treatment is based on complex strategies and takes up to years until a desired therapeutic outcome is accomplished, implying long periods of high costs and discomfort for the patient. Choosing the optimal settings for force intensities in the initial phase of orthodontic tooth movement is the key to successful orthodontic treatment. It is known that orthodontic tooth movement is mainly mediated by tensile and compressive forces that are communicated to the alveolar bone via the periodontal ligament. While the revelation of the complex molecular network was already approached by transcriptomic analysis of compressed periodontal ligament cells, the entity of molecular key players activated by tensile forces remains elusive. Therefore, the aim of this study was to assess the effect of mechanical tensile forces on the gene expression profile of human primary periodontal ligament stromal cells, mimicking the initial phase of orthodontic tooth movement. A transcriptomic analysis of tension-treated and untreated periodontal ligament stromal cells yielded 543 upregulated and 793 downregulated differentially expressed genes. Finally, six highly significant genes were found in the transcriptome that are related to biological processes with relevance to orthodontic tooth movement, including apelin, fibroblast growth factor receptor 2, noggin, sulfatase 1, secreted frizzled-related protein 4 and stanniocalcin 1. Additionally, differences of gene expression profiles between individual cell donors showed a high effect size. Closer understanding of the roles of the identified candidates in the initial phase of orthodontic tooth movement could help to clarify the underlying mechanisms, which will be essential for the development of personalized treatment strategies in orthodontics.

MALDI-TOF/MS Profiling of Whole Saliva and Gingival Crevicular Fluid in Patients with the Invisalign System and Fixed Orthodontic Appliances.

The movement of teeth by orthodontic treatment with the Invisalign (IN) system and fixed orthodontic appliances (FOA) is characterized by the reconstruction of periodontal ligaments, alveolar bone, and gingiva. A reflection of these phenomena can be found in the composition of gingival crevicular fluid (GCF). A total of 90 samples from 45 participants (45 whole saliva and 45 GCF), including 15 patients with FOA, 15 patients with IN, and 15 patients with oral health, were subjected to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF/MS) analysis. Mass fingerprints were generated for each sample. Three models were tested: a quick classifier (QC), a genetic algorithm (GA), and a supervised neural network (SNN). For both groups of samples (saliva and GCF), the GA model showed the highest recognition abilities of 88.89% (saliva) and 95.56% (GCF). Differences between the treated (FOA and IN) groups and the control group in saliva and GCF samples were determined using cluster analysis. In addition, we monitored the effect of long-term orthodontic treatment (after 6 months) in the lag phase of orthodontic tooth movement. The results show increased levels of inflammatory markers (α-defensins), which may indicate an ongoing inflammatory process even after 21 days from force application.

Xanthohumol exerts anti-inflammatory effects in an in vitro model of mechanically stimulated cementoblasts

Xanthohumol (XN) is a prenylated plant polyphenol that naturally occurs in hops and its products, e.g. beer. It has shown to have anti-inflammatory and angiogenesis inhibiting effects and it prevents the proliferation of cancer cells. These effects could be in particular interesting for processes within the periodontal ligament, as previous studies have shown that orthodontic tooth movement is associated with a sterile inflammatory reaction. Based on this, the study evaluates the anti-inflammatory effect of XN in cementoblasts in an in vitro model of the early phase of orthodontic tooth movement by compressive stimulation. XN shows a concentration-dependent influence on cell viability. Low concentrations between 0.2 and 0.8 µM increase viability, while high concentrations between 4 and 8 µM cause a significant decrease in viability. Compressive force induces an upregulation of pro-inflammatory gene (Il-6, Cox2, Vegfa) and protein (IL-6) expression. XN significantly reduces compression related IL-6 protein and gene expression. Furthermore, the expression of phosphorylated ERK and AKT under compression was upregulated while XN re-established the expression to a level similar to control. Accordingly, we demonstrated a selective anti-inflammatory effect of XN in cementoblasts. Our findings provide the base for further examination of XN in modulation of inflammation during orthodontic therapy and treatment of periodontitis.

Effect of 1% curcumin gel on myeloperoxidase activity in GCF and periodontal status in the initial phase of orthodontic tooth movement.

To explore the potential effect of locally applied 1% Curcumin on myeloperoxidase (MPO) enzymatic activity in gingival crevicular fluid (GCF) and on the periodontal status during the initial phase of orthodontic tooth movement. Forty patients (26 females and 14 males) aged 12-25 years who required fixed orthodontic treatment were randomly divided into two equal groups. The control and test groups were similar in the various baseline parameters, including standard oral hygiene protocol. Moreover, 1% Curcumin gel was applied around mandibular anterior teeth in the test group twice daily, from three days before to 14 days after the placement of archwires. MPO activity and periodontal status were recorded at five different time points; before placement of archwire (baseline), immediately after placement of archwire, 2 hours, 7 days, and 14 days later. The data were analyzed using the paired t-test for intra-group differences and the unpaired t-test for intergroup differences at five different time points. Statistical significance in the intragroup and intergroup difference of Plaque and Gingival index was calculated using the unpaired t-test. Maximum MPO enzymatic activity in GCF was observed two hours after the placement of the archwire. MPO activity decreased slightly on the seventh day, but values were still elevated as compared to baseline. However, MPO activity came back to the values similar to baseline on day 14 in the control group and significantly lower than the baseline in the test group. The inter-group differences in clinical periodontal parameters were non-significant. The locally applied 1% Curcumin gel appears to decrease the MPO activity in GCF on the 14th day after placement of the archwires. However, clinical periodontal status in the initial phase of tooth movement is unaffected by curcumin if patients adhere to good plaque control.

A Study to Evaluate Il1 And Il6 Gingival Crevicular Fluid Levels in Adolescents and Young Adults During the Early Phase of Orthodontic Tooth Movement.

Background:Evaluating the biomarkers during orthodontic therapy allows us to monitor the effectiveness of the treatment, anticipate the future outcome, and also individualize the treatment according to the response of tissue to different force intensities. The crevicular fluid analysis is a valuable diagnostic method that can be used to examine noninvasive cellular metabolic activity. The goal of this study was to compare the levels of interleukin (IL)-1 and IL-6 in the gingival crevicular fluid (GCF) of clinically healthy adolescents and young adults throughout orthodontic treatment.Methods:GCF was obtained from 20 orthodontic patients ranging in age from 11 to 28 years old. Measurements were done before (T0) and after (T24) the activation of distalization forces (T1). Enzyme-linked immunosorbent assay (ELISA) testing was used to look at IL-1 and IL-6. Two-sided t-tests were utilized as statistical testing.Results:The crevicular fluid rate (0.57 L at T0 vs. 0.95 L at T1, P = 0.001) and IL-1 levels (15.67 pg/L at T0 vs. 27.94 pg/L at T1, P = 0.009) both increased significantly between the two time periods. Only a third of the sites tested positive for IL-6. At T1, adolescents have a considerably higher amount of IL than young adults (42.96 pg/L vs. 17.93 pg/L, P = 0.006).Conclusion:Adolescent periodontal tissues are more susceptible to orthodontic forces than young adult periodontal tissues in the early stages of orthodontic treatment.

Identification of bone morphogenetic protein 4 in the saliva after the placement of fixed orthodontic appliance

BackgroundThis study was conducted in order to explore the effects of orthodontic tooth movement (OTM) on the changes of salivary proteome. This prospective observational pilot study recruited 12 healthy teenage boys with malocclusion treated with a fixed orthodontic appliance and 6 appropriate control participants. Saliva samples were collected a day before and at 0, 2, 7, and 30 days after initialization of treatment, corresponding to the initial, lag, and post-lag phases of OTM. Pooled samples were analyzed by liquid chromatography-mass spectrometry, ELISA, and Western blotting. To date, there is no published data on the presence of BMP molecules or their antagonists in the saliva or in the gingival cervical fluid related to orthodontic conditions.ResultsA total of 198 identified saliva proteins were classified based on their functional characteristics. Proteins involved in bone remodeling were observed exclusively 30 days post appliance placement, including bone morphogenetic protein 4 (BMP4), a BMP antagonist BMP-binding endothelial regulator, insulin-like growth factor-binding protein 3, cytoskeleton-associated protein 4, and fibroblast growth factor 5. Based on the analysis of protein interactions, BMP4 was found to have a central position in this OTM-related protein network.ConclusionsThe placement of a fixed orthodontic appliance induced occurrence of proteins involved in bone remodeling in the saliva at a time corresponding to the post-lag period of OTM. Limitations of this study include a relatively small sample size, limited time of monitoring patients, and the lack of interindividual variability assessment.

Evaluation of IL1β and IL6 Gingival Crevicular Fluid Levels during the Early Phase of Orthodontic Tooth Movement in Adolescents and Young Adults

Background: The crevicular fluid analysis represents a useful diagnosis tool, with the help of which noninvasive cellular metabolic activity can be analyzed. The aim of the study is to investigate comparatively IL1β and IL6 in the gingival crevicular fluid of clinically healthy adolescents and young adults during the acute phase of orthodontic treatment. Methods: Gingival crevicular fluid was collected from 20 patients (aged between 11 and 28) undergoing orthodontic treatment. Measurements were taken before (T0) and after 24 h after distalization forces were activated (T1). IL1β and IL 6 were analyzed using Elisa tests. The statistical tests used were two-sided t tests. Results: Between the two time periods there was a significant raise both in the crevicular fluid rate (0.57 µL at T0 vs. 0.95 µL at T1, p = 0.001) and in IL1β levels (15.67 pg/µL at T0 vs. 27.94 pg/µL at T1, p = 0.009). We were able to identify IL6 only in a third of the sites. There is a significantly increased level of ILβ at T1 in adolescents, more than in young adults (42.96 pg/µL vs. 17.93 pg/µL, p = 0.006). Conclusions: In the early stage of orthodontic treatment, the periodontal tissues of adolescents are more responsive to orthodontic forces than those of young adults.

Parameter identification for the simulation of the periodontal ligament during the initial phase of orthodontic tooth movement

The paper is concerned with simulation of the periodontal ligament response to force in the initial phase of orthodontic tooth movement. This is based on two previous investigations, a in vitro experiment with specimens of porcine mandibular premolars and a in vivo experiment on human upper first incisors. For the curve fit of the in vitro experiment a model function, assuming viscoelasticity, was introduced. The viscoelastic model function was augmented by a ramp rise time term, to account for observed dependence of the response on actuator velocity, and a previous load history term, to account for the effect of the previous tests on the current test. The correlation coefficient of a curve fit for all tests grouped together was Next, a curve fit of the in vivo experiment was done. Good correlation was found for a simplified model function, without viscoelastic term (). For both tests, in vitro and in vivo, the ramp rise time term improved correlation. A finite element model of the specimen of the in vitro experiment was created. For the PDL a hyperelastic constitutive model for compressible material was used and model parameters were identified. The present work indicates that the macroscopic response of the periodontal ligament to an external load can be simulated with a poro-visco-hyperelastic model. The simulation showed that poroelastic behaviour will gradually cease when viscoelastic relaxation progresses. This followed also from dimensionless analysis. As a consequence, for slow loading, or if initial response to fast loading is not of interest, a visco-hyperelastic model may suffice. To identify parameters of the finite element model several optimisation problems were solved. A model function, which can be regarded as a reduced order model, allowed a full factorial experiment (analysis) at low cost, to identify initial parameters. The thus found parameters were further refined with an optimum interpolation meta-model. That is, for limited number of parameter combinations the response was simulated with the finite element model and a refined parameter study was conducted by means of optimal interpolation. The thus found optimal parameters were verified by simulation with the finite element model. Optimal interpolation is computationally cheap, which allowed full factorial experiments at low cost.

Effects of orthodontic force magnitude on cell apoptosis and RANKL-induced osteoclastogenesis : Studies in arat model.

The aim of this study was to evaluate the time course of orthodontic force-induced apoptosis and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in arat model under light- and heavy-force conditions. Male Wistar rats were divided into light-force (10 cN) and heavy-force (60 cN) groups (N = 28/group). Each group was divided into four time-course subgroups to evaluate all phases of orthodontic tooth movement. Mesialization appliances were placed on three united maxillary molars unilaterally and activated. Tooth movements were calculated, and periodontal ligament (PDL) widths were measured. Expression of Bax, Bcl‑2, caspase3, caspase9, and RANK-RANKL were assessed by immunohistochemistry. Expression levels at the PDL-alveolar bone border were compared between experimental and control groups and force groups. The rate of tooth movement did not differ between the force groups. PDL widths were higher on the tension side in the heavy-force group in the post-lag phase. Pro-apoptotic protein Bax expression was elevated in the heavy-force group, whereas anti-apoptotic protein Bcl‑2 expression was elevated in the light-force group. RANK expression on days7 and21 and RANKL expression on day21 differed between the force groups. Evidence of orthodontic force-induced apoptosis is more robust with stronger forces than with weaker forces. Exuberant RANKL-induced osteoclastogenesis that was seen when applying alow force results from increased RANK and RANKL expression in the post-lag phase.

Genetic polymorphisms influence gene expression of human periodontal ligament fibroblasts in the early phases of orthodontic tooth movement.

Genetic polymorphisms could be involved in the individual rate of OTM (orthodontic tooth movement) corresponding to the clinical phenomenon of "slow movers" and "fast movers". This study evaluated, if genetic polymorphisms in RANK, RANKL, OPG, COX2 and IL6 are associated with the expression of RANKL, OPG, COX2 and IL6 by human periodontal ligament (hPDL) fibroblasts during OTM. Primary hPDL fibroblasts from periodontal connective tissue of teeth extracted from 57 human subjects for medical reasons were collected, isolated, cultivated and characterized. To simulate orthodontic forces in PDL pressure areas, a physiological compressive force of 2 g/cm2 was applied to the hPDL fibroblasts under cell culture conditions at 70% confluency for 48h, using a glass disc. Thereafter we analysed relative expression of RANKL, OPG, COX2 and IL6 by RT-qPCR. We also performed genotyping analysis of seven genetic polymorphisms in RANK, RANKL, OPG, COX2 and IL6. Relative gene expression was compared among the genotypes. The genotype TT in polymorphism rs9594738 (RANKL) had a higher RANKL expression in the recessive model (p = 0.021; TT vs. CT + CC). For polymorphism rs9594738 (RANKL), in the recessive model, TT was associated with a higher RANKL/OPG expression ratio (p = 0.013; TT vs. CT + CC). In the dominant model, GG genotype in rs5275 (COX2) was associated with a lower gene expression of COX2 (p = 0.04; GG vs. AA + AG). Genetic polymorphisms in genes associated with OTM affect the relative force-induced upregulation of these genes in hPDL fibroblasts.

Expression kinetics of human periodontal ligament fibroblasts in the early phases of orthodontic tooth movement.

Human periodontal ligament (hPDL) fibroblasts play acrucial mediating role in orthodontic tooth movement (OTM). In this study, we investigated the expression kinetics of genes associated with OTM in its early phase to obtain better insight into the timing and regulation of molecular and cellular signalling and transformation processes occurring in compressive areas of the periodontal ligament during OTM. Adherent hPDL fibroblasts were stimulated with physiological orthodontic compressive forces of 2 g/cm2 for 24, 48, 72, and 96 h under cell culture conditions. At each time point, we quantified relative gene expression of genes involved in bone remodelling (ALPL), inflammation (COX2, IL-6), extracellular matrix reorganization (COL1A2, P4HA1, FN1, MMP8) and angiogenesis (VEGF-A) by means of RT-qPCR as well as protein expression of osteoclastogenesis-regulating RANK-L and OPG relative to pressure-untreated controls incubated for corresponding time periods. In addition, coculture experiments with osteoclast precursor cells were performed to determine the extent of hPDL-fibroblast-mediated osteoclastogenesis (TRAP staining). As primary response to compressive forces within 24 h, we observed an induction of genes associated with angiogenesis, inflammation, osteoblastogenesis, and the remodelling of the extracellular matrix, with RANK-Lexpression at first slightly inhibited and only increased after 48 h. Major hPDL-mediated osteoclastogenesis was observed after 72 h with minor, non-RANK-L-dependent osteoclastogenesis occurring as early as 24 h after compressive force application. hPDL fibroblasts seem to play amajor mediating role in the early phase of OTM with adifferentiated, time-dependent regulation and expression pattern of cytokines and other mediators.

Assessment of Myeloperoxidase Activity at Different Force Levels in Gingival Crevicular Fluid during Initial Phase of Orthodontic Tooth Movement

Assessment of Myeloperoxidase Activity at Different Force Levels in Gingival Crevicular Fluid during Initial Phase of Orthodontic Tooth Movement

Proinflammatory mediators related to orthodontically induced periapical root resorption in rat mandibular molars.

The early phase of orthodontic tooth movement involves acute inflammatory response that may induce bone resorption. The aim of this study was to localize and quantify cells in the periodontium expressing proinflammatory mediators during orthodontically induced periapical root resorption of the rat mandibular molars. The levels of proinflammatory cytokines interleukin-1 (IL-1) α and β, tumor necrosis factor-α (TNF-α), inflammatory enzymes cyclooxygenase (COX) 1 and 2, and their product prostaglandin E2 (PGE2) in the root resorption site were compared to those in the corresponding area of the untreated periodontal ligament (PDL) of physiologically drifting teeth. Continuous heavy orthodontic force was applied to the mandibular first molar for 8 and 15 days while in occlusion to induce root resorption. Frozen sections including root resorption lacunae were analyzed for the activity of non-specific esterase (NSE) and tartrate-resistant acid phosphatase (TRAP) by enzyme histochemistry and for the expression of IL-1α, IL-1β, TNF-α, COX-1, COX-2, and PGE2 by immunohistochemistry. The active root resorption lacunae had significantly more TRAP-positive multinucleated odontoclasts, whereas the number of NSE-positive cells of the monocyte-macrophage lineage did not differ from that in the control PDL. Several types of periodontal cells exhibited a significant increase in the expression of IL-1α, IL-1β, TNF-α, COX-2, and PGE2 in the root resorption zone, while COX-1 was rarely detected. These data suggest that proinflammatory mediators expressed in periodontal cells may synergistically promote apical root resorption in response to continuous heavy mechanical force applied to teeth.

Assessment of Myeloperoxidase Activity at Different Force Levels in Gingival Crevicular Fluid during Initial Phase of Orthodontic Tooth Movement

Assessment of Myeloperoxidase Activity at Different Force Levels in Gingival Crevicular Fluid during Initial Phase of Orthodontic Tooth Movement

Differences in IL-1β and IL-6 levels in the gingival crevicular fluid during acute phase of orthodontic tooth movement between juveniles and young adults

Background/Aim. There is little information, about the difference in cytokine levels in the gingival crevicular fluid (GCF) during orthodontic tooth movement (OTM), between juveniles (children) and young adults (adults). The aim of this study was to examine the levels of interleukins IL-1? and IL- 6 in GCF of these two age groups during the acute phase of OTM. Methods. The subjects, 10 children and 10 adults, underwent OTM of a single tooth, with an untreated antagonistic tooth used as the control group. GCF was sampled from both the control and treatment sites right before the beginning (the baseline) and 24 h, 72 h and 168 h upon initiation of OTM. Cytokine levels were determined by enzymelinked immunosorbent assay (ELISA). Results. The levels of both GCF IL-1? and IL-6 showed a bimodal peak during early phase of OTM, at 24 h and 168 h, in both age groups. As the statistic has shown, the increase in IL-1? levels was more prominent after 168 h in treated teeth of children, compared to both children?s control teeth and treated teeth of adults, whilst the GCF IL-6 levels in the same group increased significantly after 24 h, as well as after 168 h, approximately 70 and 55 fold, respectively. In the same time periods the increase of IL-6 levels in GCF of adults was notably lesser, averaging approximately 5 and 10 fold, respectively, compared to the control teeth. In addition, the amount of tooth movement was statistically larger for children than for adults 168 hours upon the initiation of OTM. Conclusion. GCF IL-1? and IL-6 were increasingly expressed during initial phase of OTM in both children and adults. However, excretory response of cytokines in children?s GCF, especially the concentration of IL-6, was at a significantly higher level than that of adults?, which accords to the finding that the initial OTM is faster in children.

Biochemical characterization of human gingival crevicular fluid during orthodontic tooth movement using Raman spectroscopy.

This study used Raman spectroscopy to report the first human gingival crevicular fluid (GCF) biochemical characterization during the early phase of orthodontic tooth movement. This technique allows for label-free and noninvasive biochemical change monitoring in GCF during orthodontic tooth movement. Ten orthodontic patients (20.8 ± 2.5 years) participated in the study. GCF samples were obtained before (baseline, 0 days) and during orthodontic treatment at 1, 7 and 28 days. For Raman spectroscopic measurement, GCF samples (5 µl) were deposited onto a gold-coated substrate, then dried at room temperature. Raman spectra GCF analysis during orthodontic treatment indicated that the hydroxyapatite to primarily collagen-dominated matrix band (phosphate 984 cm(-1)/amide I 1667 cm(-1)) intensity ratio decreased at day 7 (P < 0.05). The carbonate apatite to hydroxyapatite ratio (carbonate 1088 cm(-1)/phosphate 984 cm(-1)) was significantly higher on day 7 compared to day 0 (P < 0.05). These results indicate that demineralization occurs during the alveolar bone remodeling process. We also found notable peak shifts in the amide I range during orthodontic tooth movement. The 1658 cm(-1) in baseline red shifted to 1667 cm(-1) at orthodontic treatment day 7. Curve fitting in the amide I (1615-1725 cm(-1)) range demonstrated that increased random coil conformation was accompanied by a decrease in β-sheet structure during orthodontic tooth movement. Thus, we suggest Raman spectroscopy could be used for label-free, non-invasive GCF quality assessment during orthodontic tooth movement. Furthermore, this method may prove to be a powerful diagnostic and prognostic tool for monitoring orthodontic tooth movement in a clinical setting.

Cellular response to orthodontically-induced short-term hypoxia in dental pulp cells

Orthodontic force application is well known to induce sterile inflammation, which is initially caused by the compression of blood vessels in tooth-supporting apparatus. The reaction of periodontal ligament cells to mechanical loading has been thoroughly investigated, whereas knowledge on tissue reactions of the dental pulp is rather limited. The aim of the present trial is to analyze the effect of orthodontic treatment on the induction and cellular regulation of intra-pulpal hypoxia. To investigate the effect of orthodontic force on dental pulp cells, which results in circulatory disturbances within the dental pulp, we used a rat model for the immunohistochemical analysis of the accumulation of hypoxia-inducible factor-1α in the initial phase of orthodontic tooth movement. To further examine the regulatory role of circulatory disturbances and hypoxic conditions, we analyze isolated dental pulp cells from human teeth with regard to their specific reaction under hypoxic conditions by means of flow cytometry, immunoblot, ELISA and real-time PCR on markers (Hif-1α, VEGF, Cox-2, IL-6, IL-8, ROS, p65). In vivo experiments showed the induction of hypoxia in dental pulp after orthodontic tooth movement. The induction of oxidative stress in human dental pulp cells showed up-regulation of the pro-inflammatory and angiogenic genes Cox-2, VEGF, IL-6 and IL-8. The present data suggest that orthodontic tooth movement affects dental pulp circulation by hypoxia, which leads to an inflammatory response inside treated teeth. Therefore, pulp tissue may be expected to undergo a remodeling process after tooth movement.

Time-related changes in salivary levels of the osteotropic factors sRANKL and OPG through orthodontic tooth movement

In this study, we aimed to determine whether the variations in salivary concentrations of soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG), and their ratios, might be linked with the different phases of orthodontic tooth movement. Twenty healthy subjects who required fixed appliance therapy not involving tooth extractions or surgical procedures were selected. Unstimulated whole saliva samples were collected from each patient before fitting the orthodontic appliances, and at 24 to 48 hours, 2 weeks, 5 weeks, and 8 weeks after the activation. Salivary sRANKL and OPG concentrations were determined by enzyme-linked immunosorbent assays. The data were analyzed by using nonparametric statistics. Overall, median values of sRANKL showed significant increases, median OPG salivary values showed a significant downward trend, and the sRANKL/OPG ratio tended to increase significantly over time after the activation visit. However, clear fluctuations in the immunoenzymatic findings were noted at the different sampling times, indicating nonlinear trends in the levels of the biomarkers through time. Post-hoc pairwise comparisons showed significant differences between (1) all sRANKL values relative to those of the 8-week sampling time; (2) baseline/8-week OPG salivary levels; and (3) baseline, 24 to 48 hours, and 2-week sRANKL/OPG ratios compared with those of the 8-week test. The findings indicate that variations in salivary concentrations of sRANKL and OPG and their ratios might be linked to the different phases of orthodontic tooth movement. Hence, these analytes might serve in a panel of salivary functional biomarkers that could assist in the screening of orthodontic treatment in clinical practice.

Screening for salivary levels of deoxypyridinoline and bone-specific alkaline phosphatase during orthodontic tooth movement: a pilot study

Deoxypyridinoline (DPD) and bone-specific alkaline phosphatase (BAP) have been regarded as systemic determinants of bone remodelling. Owing this fact, this study aimed to determine whether the variations in the salivary concentration of these two biomarkers as detected through a longitudinal follow-up with four consecutive visits may be linked with the different phases of orthodontic tooth movement (OTM). Twenty-two healthy subjects who required fixed appliance therapy not involving tooth extractions/surgical procedures were selected. Unstimulated whole saliva samples were collected from each patient prior to fitting the orthodontic appliances and 24-48 hours, 2 weeks, and 5 weeks after the activation. Salivary DPD and BAP concentrations were determined by enzyme-linked immunosorbent assay. The data were analysed using non-parametric statistics. There were no statistically significant differences in salivary levels of biomarkers regarding demographic and clinical parameters. Overall, although DPD values revealed an increasing nature after force application and BAP values showed a descending trend, only the former showed statistically significant changes over time. Furthermore, p ost hoc comparisons for DPD salivary levels revealed significant differences between every paired sampling times, except for the pair baseline test/24-48 hours test. Synchronously, a moderate positive significant correlation between both salivary biomarkers was observed at 2 weeks test. The findings indicate that although salivary levels of DPD and BAP may act as indicators of increased bone remodelling, it appears that DPD dominates the earlier phases of OTM, whereas BAP might serve as indicator of bone formation as soon as the tooth movement stops.

Non-steroidal and steroidal anti-inflammatory use in the context of orthodontic movement

The early phase of orthodontic tooth movement involves sterile acute inflammation of the periodontal ligament in response to biomechanical forces. Anti-inflammatories are pharmacologic agents used in medical and dentistry clinics. The aim of the study was to analyse the bone remodelling during orthodontic movement under non-steroidal and steroidal treatment. Male Wistar rats (n = 90) were randomly divided into three groups: C (control), non-steroidal anti-inflammatory drug (NSAID; potassium diclofenac), and steroidal anti-inflammatory drug (SAID; dexamethasone dissodium phosphate). The animals of the C group received 0.9 per cent saline solution, the NSAID group received potassium diclofenac CATAFLAM® (5 mg/kg), and the SAID group received dexamethasone dissodium phosphate DEXANIL® (2 mg/kg). Animals were sacrificed 3, 7, or 14 days after placement of the orthodontic appliance. The upper first molars were processed histologically; we quantified the blood vessels, Howship lacunae, and osteoclast-like cells present on the tension and compression sides of the periodontal ligament. Bone formation was evaluated under polarized light microscopy; 4.5 Image Pro-Plus® software calculated the percentage of immature/mature collagen present. The results showed that, in 3 and 7 days, NSAID and SAID groups presented fewer blood vessels, Howship lacunae, and osteoclast-like cells when compared to the control group. On the 7th and 14th days, there was a lower percentage of mature collagen in the SAID group (P < 0.001). These data demonstrate that potassium diclofenac and dexamethasone inhibit bone resorption during the initial period of orthodontic movement and that dexamethasone delays the collagen maturation process in established bone matrix.