Review Cytokines and Orthodontic tooth * Dr. Sharath Kumar Shetty, **Dr. Mahesh Kumar. Y, *** Dr. Smitha. P. L. * HOD and Professor, Director-PG Studies, ** Professor, *** PG Student Dept. of Orthodontics and Dentofacial Orthopaedics, KVG Dental College & Hospital, Sullia. D.K.. Abstract The main aim of this study is to evaluate cytokines in the gingival crevicular fluid (GCF) during orthodontic treatment, summarizing the regulation patterns of the most commonly studied cytokines and their clinical implications. Association exists between Prostaglandin E 2 (PGE 2 ) and Interleukin-(1L-1β) and pain, velocity of the tooth and treatment mechanics. IL-1β and PGE 2 showed different patterns of upregulation with IL-1β being more responsive to mechanical stress and PGE 2 more responsive to synergistic regulation of IL-1β and mechanical force. The results might be taken to support, at the cellular level, the use of light continuous forces for orthodontic treatment. Key words: Gingival crevicular fluid, Cytokines, Orthodontic tooth, Interleukin-1β. Journal of Dental Sciences & Research 2:1: Pages 132-141 Introduction During orthodontic treatment, the early response of periodontal tissues to mechanical stress involves several metabolic changes that allow tooth. The PDL, the soft tissue matrix that joins the dental root to the alveolar bone, is composed of an intricate network of blood vessels, and nerve endings, the principal cellular components. Orthodontic force produces a distortion of PDL matrix resulting in an alteration in cellular shape and cytoskeletal configuration, neuropepitide release, from afferent nerve endings. At the bimolecular level, these forces may induce the release of PGs, growth factors and cytokines. 1 Successful orthodontic tooth requires the remodeling of the periodontium, the particularly alveolar bone. When a small force is applied for a prolonged period, an inflammatory event occurs, with 132 Journal of Dental Sciences and Research
in the periodontium, resulting in bone resorption that accommodates the of the tooth. 2 Mechanical stress from orthodontic appliances is considered to induce cells in the periodontium to form biologically active substances, such as cytokines and enzymes, responsible for connective tissue remodeling. These substances can be monitored non-invasively in humans by following changes in the compositions of GCF during orthodontic tooth. 3 The interest of most reports was focused on the presence of new mediators and on the upregulation, down-regulation of the levels of these regulatory proteins in different treatment designs. 4 Among the more than 100 regulatory proteins detected in GCF, this review will focus on cytokines. Cytokines are biologically active substances expressed by the cells in the periodontium in response to mechanical stress. IL-1 is a polypeptide cytokines produced primarily by cells of the mononuclear phagocytic lineage. Target cell type includes osteoblasts and IL-1 generally promotes proinflammatory response. 5 The pleiotropic action of cytokines include numerous effects on cells of immune system and modulation of inflammatory response. Many characteristic features of cytokines makes them particularly interesting to orthodontics, as cytokines in GCF reflect the local microenvironment of periodontal tissue, the area where upon the effect of orthodontic force is exerted. Materials and Methods A number of key databases (medline, pubmed, embase, web of science) were searched in Jan 2010, using mesh terms of orthodontics tooth and crevicular fluid and using the free text terms of GCF, cytokines, inflammatory factors, regulatory proteins, tooth displacement, canine distalization, and root resorption. The search results from each databases were combined. The inclusion criteria were: human studies on GCF, cytokines (including prostaglandins, tumor necrosing factor, Interleukins, growth factors, colony-stimulating factors, and interferons) or their receptors as study mediators, orthodontic mechanics, GCF sampling and handling methods, cytokines measured, number of study subjects >= 5, or number of study teeth >= 10, proper oral hygiene control, no use of antibiotic/anti-inflammatory drugs before tooth and GCF sampling. The exclusion criteria were: animal studies, in vitro studies, studies on human GCF enzymes or any metabolic products other than mentioned in the inclusi on criteria. 133 Journal of Dental Sciences and Research
The data were extracted in 3 categories 1.Orthodontic mechanics Number of study subjects, age of study subjects, control systems and tooth and treatment mechanics (appliances, force magnitudes, force reactivations) studied. 2. GCF sampling and handling methods Most studies had a sampling time of 30s and sampled repeatedly with either no time interval or with intervals of 1min, 5 min, 10 min. The storage temperature was -20-30 o c, or - 70-80 o c. The cytokine levels were presented differently and expressed in terms of weight, of total GCF protein or of total GCF volume. So, the sampling methods (paper strips, volume/weight measuring, repeated sampling), storage systems (buffer, temperature) and cytokine measurements (assays, total amount/, measurement units) were studied. 3. Cytokine measurements Duration of the study, number of samples, time-points and sites (pressure/tension), target cytokines, up-regulation or down-regulation and peak levels were studied. Cytokines levels were up-regulated in most studies and many cytokines peak at 24h, irrespective of treatment mechanics. RESULTS The studies are listed in Table1 (orthodontic mechanics), Table2 (GCF sampling methods) and Table3 (cytokine measurements). 134 Journal of Dental Sciences and Research
Table 1 : GCF cytokines and orthodontic tooth : Orthodontic mechanics Reference N Age Control Tooth Force System Force Reactivations (yr) (cn) 6 60 - Baseline UCI,LI Fixed orthodontic treatment - No 7 9 10-18 Base Line UIM,CI Modified hyrax appliance - Yes,1week 8 10 15±1 Baseline UC Hybrid Retractor, - No Distraction 9 10 15±4 Antagonistic UC Sectional, 60,120, No Distalizing 240N 10 18 9-14 Antagonistic UM Separation Elastics - No 11 18 16-19 Baseline UC 0.014 NiTi, aligning - No 12 15 15±3 Control & UC Elastic Chain, 250 No antagonistic distalyzing 13 10 15±2 Control & UC Elastic Chain, 250 No antagonistic distalyzing 14 15 17±2 Baseline UC 0.014 NiTi, - No aligning 15 18 9-14 Antagonistic UM Separation Elastics - No 16 19 22±2 Contralatera UC Elastic Chain, 250 No l distalyzing 3 10 23±2 Control & Antagonistic UC Elastic Chain, distalyzing 250 No 5 10 10-30 Antagonistic UC Sectional, 18,60 No distalyzing 17 10 15-17 Baseline LC,UC Sectional, distalyzing 90,115 No 18 10 18-22 Antagonistic UC, LC Sectional, distalizing 100 Yes, 1 Week 19 43 10-14 Contralatera ULI 0.012 NiTi 70 No l aligning 41 21-27 Contralatera ULI 0.012 NiTi 70 No l aligning 20 7 12-16 Antagonistic UC Sectional, distalizing 18,60 No 21 12 14 Control & UC Elastic chain 250 No Antagonistic distalizing 22 12 14 Control& Antagonistic UC Elastic chain distalizing 250 No 1 20 13-36 Baseline UC Elastic ligature, 150 No distalizing 2 10 24-27 Contralatera l ULI 0.014 NiTi, Aligning 100 No Tooth -UM, upper molar: LC, lower canine: UC, upper canine: UCI, upper central incisor: ULI, upper lateral incisor. 135 Journal of Dental Sciences and Research
Table-2 GCF sampling and handling methods Reference Sampling duration (sec) Repeated sampling Storage temperature ( 0 C) Measuring total amount/ Expressing in 6 30 1min -80 Total protein ng /µl -1 7 30 - - Protein pg 8 30 4/1min -80 Concentration pgµl -1 9 30 2/1min -70 Protein ng µl -1 10 20 No -70 Total amount pg 11 30 No -20 Concentration pg µl -1 12 60 2/min -30 Concentration pg µl -1 13 60 2 min -30 Concentration pg µl -1 14 30 No -20 Total amount pg 15 20 No -70 Total amount pg 16 60 2/0min -30 Protein 3 60 2/1min -30 Protein 5 30 2/1min -70 Protein 17. 30 2/1min -70 Total amount 18 30 4/1min -70 Protein 19 30 2/5 min -80 Total amount 20 30 2/1 min -70 Protein 21 30 2/1 min -30 Protein 22 30 2/1 min -30 Protein pg µg -1 ng µl -1 ng µl -1 pg pg µl -1 Pg µg -1 pg pg µl -1 IL-1β in ngg -1 pg/ µg -1 pg µg -1 1 - No - Total amount ng 2 30 2/1 min -80 Total amount pg 136 Journal of Dental Sciences and Research
Table 3 Cytokine measurements Ref Duration Sampling Cytokine U/D Peak Main results points 6 7d - OPN RANKL - - Increased levels of OPG, RANKL with root resorption during Orthodontic tooth 7 21d 3,8,30days IL-1β & BG - 24 hr Increased levels of IL - 1β & BG during orthodontic /orthopedic force application 8 7d 0,1,24,168 hours 9 84d 0,1,3,7,14,28, 42, 56,70,84d 10 14d 0,1min,1h,1d, 7d IL-1β PGE 2 11 6 months 0,7,21,6month IL-1β s +7d,21d TNF-α 12 7d 0,1,24,168 h RANKL OPG 13 7d 0,1,24,168 h RANKL OPG 14 6 months 0,7d,21d,6mon IL-2 ths +7d,+21d IL-6 IL-8 15 7d 0,1,24,168 h Ih-1β Pg E 2 TNF-α 24 hr Hybrid no change with time distraction higher than hybrid IL-1β - - Tooth rate relate to IL-1ra IL-1 gene polymorphisms 24 hr Higher levels in tension sites. Higher levels in tension sites - - Tend to increase Tend to increase UP 24 hr Lower ratio values in adults Down Lower ratio values in adults UP 24 hr No changes at 1hr/168h Down No changes at 1hr/168h - - Tend to increase 7d,back at 21d - - Decrease at 7d, back to baseline Down 7 d at 21d Associated with pain at 24h Weak association with pain at 1hr 16 7d 0,1,4,8,24,72,1 IL-1β Correlated with P substance 20,168,h 3 7d 0,1,24,168hr t-pa Increased only at 24h PAI 5 84d -28,- 24,0,1,3,14,28, IL-1β IL-1ra - - The ratio of the 2 correlate with the rate of tooth 42,56,70,84d 17 30d 0,1,24,6,10,30 d IL-8 - - Tend to increase with early phase 18 3week 0,1,24,168h Repeat twice IL-1β 24h Higher level at reactivate PGE 2 24h Remain higher for 1week 19 0, PGE 2 regulated in both age groups IL-6 GM-CSF - Increased only in youngsters Increased only in adults 20 84d -28,- 14,0,1,3,14,28, 42,56,70,84d IL-1β IL-1.G 21 7d 0,1,24,1684 IL-1β IL-6 EGF TNF-α <3day <3day No changes No changes at 1 hr or 168 hr No changes at 1hr or 168hr No changes at 1hr or 168hr No changes at 1hr or 168hr 22 7d 0,1,24,1684 TGF-B1 No change at 1 hr / 168 hr 1 5 min 0,5 min TNF-α - More than twofold increase 137 Journal of Dental Sciences and Research
2 7d 0,1,24,48,168h r IL-1β PGE 2 24h Increased at 1h, back to baseline at 168hr Stay high at 48h, back to baseline at 168hr. TNF-α, Tumor necrosis factor :IL-Iβ, interleukin 1β : IL-Ira, Interleukin I receptor antagonist: PGE 2,Prostaglandin :RANKL, Receptor activator of nuclear factor-kb ligand: OPG,Osteoprotegerin: IL-2, Interleukin 2: IL-6, Interleukin 6: IL-8, Interleukin 8: t-pa, tissue-type plasminogen activator : TGF-B1, Transforming growth factor: EGF, Epidermal growth factor :PAI,Plasminogen activator inhibitor :GM-CSF, Granulocyte macrophage colony-stimulating factor, U/D, up-regulation or down-regulation. Discussion This is an attempt to review systematically evaluated studies on Cytokines that are expressed in GCF during orthodontic tooth. Most of the results were the peak levels of the various Cytokines measured 24h after applying an orthodontic force, irrespective of treatment mechanics. GIANNOPOULOU et.al 15 reported that the intensity of pain at 1h was associated with PGE 2 levels, where as pain intensity at 24h was associated with IL-1β levels. VAMAGUCHI et al 16 showed a significant correlation between IL-1β and substances P, a peptide involved in pain, neurotransmission, during orthodontic treatment in adults. IWASAKI et al 5, 20 found a positive correlation with the IL- 1β:IL-1 receptor antagonist(il- 1ra) ratio. They suggested that the speed of tooth is related to stress and to IL-1 gene cluster polymorphisms. Interlukin-6 and granulocyte macrophages colony stimulating factor (GM- CSF)showed less responsiveness in adults than in Juveniles. 12,19 LEE et.al 18 compared the production of pge 2 and IL-1β to continuous/interrupted force, showed different responses: PGE 2 levels showed less consistent changes with different force regimens than IL-1β. IL-1β levels may reach a significant elevation between 1h. 10,15,2 SUGIYAMA et al 23 found that amount of Cathepsin B ingcf is increased by orthodontic tooth. This increased Cathepsin B may be involved in extracellular matrix degradation in response to mechanical stress. The peak of IL-1βhas been observed at 24h, 16,18,21 and 72h. 1 Without force reactivation, IL-1β has been shown to decrease significantly at 168h to baseline level, but with force reactivation it reached an even higher peak. 21 A heavy decaying force1 6,21 tend to result in a significant 138 Journal of Dental Sciences and Research
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