Interleukin-1beta and beta-glucuronidase in gingival crevicular fluid from molars during rapid palatal expansion

Rapid maxillary expansion supplementary methods: A scoping review of animal studies

INTRODUCTION

Maxillary constriction is a relatively common condition. Various treatment modalities have been proposed for this condition such as rapid maxillary expansion (RME). Although RME can significantly expand the suture in a relatively short period of time, it has a number of drawbacks, mainly a lengthy retention period. The primary objective of this study was to assess the efficacy of the supplementary methods used in conjunction with RME for new bone formation (NBF) at the midpalatal suture (MPS). Relapse, bone healing, and root resorption were also studied as the secondary outcomes.

MATERIALS AND METHODS

The PubMed, Embase, and Cochrane library online databases were searched according to the PRISMA-ScR guideline. Animal studies on the effects of non-surgical supplementary methods other than laser therapy on NBF in RME were included and reviewed.

RESULT

Thirty-eight articles met the inclusion criteria. The supplementary methods were categorized into 6 groups: hormones, chemical agents, drugs, vitamins, proteins, and some other substances, which could not be assigned to any group. All the aforementioned substances enhanced NBF. Drugs such as bisphosphonates also increased bone resorption. The oestrogen hormone was shown to reduce treatment relapse. Lastly, stem cell application accelerated bone healing at the expanded MPS.

CONCLUSION

Administration of hormones, chemical agents, drugs, vitamins, herbs, and proteins may improve the outcomes of RME, shorten the retention period and consequently, reduce relapse in animals. However, the generalizability of these findings is limited due to the insubstantial number of studies published on each substance.

Comparison of cytokine level changes in gingival crevicular fluid between the aligner and pendulum appliance during early molar distalization : A single-center, prospective, observational study

PURPOSE

There is currently a lack of evidence pertaining to gingival crevicular fluid cytokine levels in patients treated with the pendulum appliance. This study aimed to compare changes in cytokine secretion levels in gingival crevicular fluid (GFC) between the aligner and pendulum appliance in patients undergoing molar distalization.

METHODS

GFC samples were collected from 28 participants with asymmetrical dental class II malocclusion who were undergoing molar distalization using aligners or pendulum appliances. An enzyme-linked immunosorbent assay was used to detect cytokine secretion levels during asymmetrical molar distalization for up to 14 days. Periodontal health indices and tooth movements were also assessed.

RESULTS

No significant difference was found for the distalization distance between the two appliances. The Silness and Loe Plaque Index and Lobene Modified Gingival Index increased in the pendulum group but not in the aligner group at 14 days. Interleukin-1β and tumor necrosis factor‑α were upregulated in both groups. In the pendulum group, receptor activator of nuclear factor kappa‑Β ligand and osteoprotegerin secretion levels were significantly upregulated and downregulated, respectively; smaller changes in these two cytokines were observed in the aligner group.

CONCLUSIONS

Pendulum appliances exert stronger forces than aligners, which cause more changes in the secretion of inflammatory mediators in young patients.

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.

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.

Levels of Cytokines in Gingival Crevicular Fluid during Rapid Maxillary Expansion and the Subsequent Retention Period

OBJECTIVE

To monitor the effects of rapid maxillary expansion (RME) on bone metabolic activities during and after 3 months of retention.

STUDY DESIGN

Fifteen patients with a mean age of 12.9 ± 0.6 years were treated with a bonded expansion device, activated 2 turns per day. The retention period was 3 months. Clinical periodontal parameters were recorded at baseline and after retention. Gingival crevicular fluid (GCF) samples were collected from maxillary first molars from the compression sides at baseline, then at 1 and 10 days and after retention. Tension side samples were obtained at baseline and after retention. Interleukin-1beta (IL-1β), transforming growth factor beta1 (TGF-β1), prostaglandin E₂ (PGE₂) and nitric oxide (NO) levels were specifically measured.

RESULTS

Periodontal parameters increased significantly after retention relative to baseline values. Levels of IL-1β, TGF-β1 and PGE₂ increased on day 10, and decreased after retention on the compression side. NO levels were elevated on day 10, and remained higher after retention on the compression side. Tension side cytokine levels remained higher relative to baseline values after retention.

CONCLUSIONS

The results of this study indicate the importance of ongoing adaptive bone activities after 3 months of retention with RME, which should be considered questionable as an effective retention period.

Association among pain, masticatory performance, and proinflammatory cytokines in crevicular fluid during orthodontic treatment

INTRODUCTION

Orthodontic patients usually complain about masticatory limitations associated with the activation of fixed appliances. The aim of this investigation was to evaluate whether orthodontic pain reflects differences in the objective evaluation of mastication and in the levels of proinflammatory cytokines in the crevicular fluid of patients undergoing orthodontic treatment.

METHODS

Twenty patients with malocclusions requiring orthodontic treatment were included in this prospective study. Their pain experience, masticatory performance, and levels of interleukin 1-beta and prostaglandin E2 in crevicular fluid were evaluated at 3 times: before bracket placement, 24 hours after archwire placement, and 30 days after the initial appointment. All variables were compared with those of a control group of 25 subjects with normal occlusion.

RESULTS

The masticatory performance of the patients was significantly reduced at 24 hours after bracket placement, the period in which they reported higher values of pain and had higher levels of interleukin 1-beta. The levels of prostaglandin E2 did not change in the periods evaluated, and there were no correlations between the levels of cytokines and the functional limitations observed. The only significant correlation was between pain and decreased masticatory performance.

CONCLUSIONS

The masticatory performance of orthodontic patients is significantly reduced only during the period of greatest pain. However, these alterations did not correlate with any measurement of interleukin 1-beta or prostaglandin E2 in the crevicular fluid, suggesting that these solitary measurements are inadequate to predict the temporary pain and masticatory limitations experienced by patients undergoing orthodontic treatment.

Biomarkers of Orthodontic Tooth Movement in Gingival Crevicular Fluid: A Systematic Review

BACKGROUND

The analysis of gingival crevicular fluid (GCF) may be an acceptable way to examine the ongoing biochemical processes associated with bone turnover during orthodontic tooth movement. If it is possible to biologically monitor and predict the outcome of orthodontic forces, then the management of appliances could be based on individual tissue responses, and the effectiveness of the treatment could be improved.

METHODOLOGY

A literature search was carried out in major databases, such as medline, EMBASE, cochrane library, web of science, google scholar and scopus for relevant studies. Publications in English between 2000 and 2014 which estimated GCF markers as indicators of orthodontic tooth movement were included.

RESULTS

The list of biomarkers available to date was compiled and presented in table format. Each biomarker is discussed separately based on the available evidence.

CONCLUSION

Several sensitive GCF markers are available to detect the biomechanical changes occurring during orthodontic tooth movement. Further focused research might help to analyze the sensitivity and reliability of these indicators, which in turn can lead to the development of chairside tests to assess the outcome of orthodontic therapy.

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.

Myeloperoxidase enzymatic activity is increased in patients with different levels of dental crowding after initial orthodontic activation

INTRODUCTION

Orthodontic tooth movement implies application of forces that generate an inflammatory process. The myeloperoxidase (MPO) enzyme is found inside neutrophil granules. MPO activity indirectly reflects the level of inflammation. The aim of this study was to measure MPO activity in gingival crevicular fluid (GCF) and whole saliva in orthodontic patients with different levels of dental crowding at the alignment phase of orthodontic treatment with the same archwires.

METHODS

Twenty patients were classified according to the irregularity index into 2 groups: severe and minimum crowding (10 in each group). MPO activity was evaluated in GCF and saliva at 0 and 2 hours, and 7 and 14 days after the orthodontic appliances were activated. MPO activity was measured using the modified Bradley-Bozeman technique.

RESULTS

In both groups, the maximum activity was at 2 hours (P <0.05) after activation. MPO activity remained elevated until day 7, and values similar to baseline were found at day 14 in the GCF and saliva samples. Enzymatic activity did not show statistical differences between the groups.

CONCLUSIONS

The amount of dental crowding does not seem to influence MPO activity, which showed similar patterns in GCF and saliva, but the values in GCF reflected the inflammatory changes more accurately than did the values in saliva. The quantification of MPO activity is a useful biologic marker as an indirect measurement of inflammation generated with tooth movement independent of the amount of crowding.

Understanding the advances in biology of orthodontic tooth movement for improved ortho-perio interdisciplinary approach

This article provides an insight on detailed current advances in molecular understandings of periodontal ligament cells and the influence of orthodontic force on them in the light of recent advances in molecular and genetic sciences. It sequentially unfolds the cellular events beginning from the mechanical force initiated events of cellular responses to bone remodeling. It also highlights the risks and limitations of orthodontic treatment in certain periodontal conditions, the important areas of team work, orthodontic expectations from periodontal treatment and the possibility of much more future combined research to improve the best possible periodontal health and esthetic outcome of the patient.

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

Background

This study provides a vital insight in assessing the clinical and biochemical changes in interleukin (IL)-1β levels in peri-miniscrew crevicular fluid (PMCF) during the course of orthodontic tooth movement.

Methods

The study comprised the analysis of IL-1β in peri-miniscrew crevicular fluid obtained from crevices around the miniscrews inserted in 11 patients (eight females and three males, mean age 17.3 ± 4.64 years) with all first premolar extraction and maximum anchorage requirement using miniscrew-supported anchorage. Miniscrews were loaded at 3 weeks after placement by 200-g nitinol closed coil springs of 9-mm length for en masse retraction. Peri-miniscrew crevicular fluid was collected at miniscrew placement (T1), at 3 weeks (T2/baseline) and on loading at 0 (T3) and 1 day (T4), 21 (T5), 72 (T6), 120 (T7), 180 (T8) and 300 (T9) days. IL-1β levels were estimated by enzyme-linked immunosorbent assay (ELISA). Peri-miniscrew tissue was examined for signs of inflammation, and also, miniscrew mobility was assessed with Periotest and handles of two mouth mirrors.

Results

IL-1β levels in all miniscrews were significantly higher at T1 and peaked again at T4 showing a bimodal peak. However, there was a gradual and statistically significant decrease in IL-1β till T5, while further changes till the end of the study were statistically not significant.

Conclusions

The changing levels of IL-1β levels in PMCF over a duration of 300 days are suggestive of the underlying inflammatory process. IL-1β levels in PMCF show a significant rise during miniscrew insertion and on immediate loading. The trend of gradually reducing IL-1β levels around the miniscrew over the period after loading towards baseline is suggestive of adaptive bone response to stimulus.

Response of immortalized murine cementoblast cells to hypoxia in vitro

OBJECTIVES

The aim of the study was to investigate the impact of hypoxia on proliferation, apoptosis and mineralization of cementoblast-like cells (OCCM-30) in vitro.

METHODS

The effects of different periods of hypoxia (2% O2) on proliferation, apoptosis, cementoblastic potential and root cementum resorption capability of OCCM-30 were evaluated, by using MTT, flow cytometry, alkaline phosphatase (ALP) activity assay, reverse transcription-polymerase chain reaction measurement, enzyme-linked immunosorbent assay and mineralization nodule formation assay.

RESULTS

OCCM-30 viability was significantly inhibited by hypoxia while the apoptosis ratio was enhanced in a time-dependent manner; hypoxia inducible factor-1α and vascular endothelial growth factor mRNA were induced by hypoxia in different manners; temporary hypoxia (<24 h) stimulated cementoblastic function of OCCM-30, while long-term hypoxia inhibited it, manifested by decreased mRNA level or release of ALP, osteocalcin, bone sialoprotein, osteopontin and osteoprotegerin. In addition, hypoxia affected mineralized nodule formation of OCCM-30 in a time-dependent fashion; moreover, root cementum resorption function was also induced by hypoxia, manifested by increased receptor activator of nuclear factor kappa B ligand mRNA and protein expression.

CONCLUSION

Temporary exposure of OCCM-30 to hypoxia inhibited proliferation, promoted apoptosis and mineralization, while longer duration of hypoxia could inhibit the cementoblast function. The findings may provide theoretical basis for developing novel therapeutics to prevent root resorption during orthodontic treatment.

Metabolic changes of human dental pulp after rapid palatal expansion

OBJECTIVES

To investigate rapid palatal expansion (RPE)-induced metabolic changes in human dental pulp by measuring the expression and activity of aspartate aminotransferase (AST).

METHODS

mRNA and protein levels of AST in human dental pulp were measured by quantitative real-time polymerase chain reaction and Western blot, respectively. Furthermore, the activity of AST was measured by a full automatic biochemical analyzer.

RESULTS

AST mRNA and protein levels were found to be expressed in normal dental pulp. Moreover, the expression of AST was increased significantly after 14 days of RPE and then decreased at 1 month in retention. Three and 6 months after RPE, the AST expression level was gradually decreased to its baseline level. Similarly, AST activity was significantly elevated after 14 days of RPE, which was then down-regulated at 1 month in retention but was still kept at a higher level as compared with the control group. The enzymatic activity of AST was slowly decreased to its baseline level at 3 and 6 months in retention.

CONCLUSIONS

These results showed that significant reversible metabolic changes occurred in dental pulp during RPE, which revealed the high capacity of the pulp tissue for adaptation to this orthopedic method.

Involvement of COX-2/PGE2 signalling in hypoxia-induced angiogenic response in endothelial cells

To evaluate the impact of hypoxia on the angiogenic capability of endothelial cells (ECs), and further investigate whether the cyclooxygenase-2 (COX-2)/prostaglandin E(2) (PGE(2)) signalling is involved in the angiogenic response of ECs to hypoxia. We explored the impact of various periods (1, 3, 6, 12, 24 hrs) of hypoxia (2% O(2)) on human umbilical vein endothelial cells (HUVECs) in vitro. We observed cell viability, migration, tube formation, analysed COX-2, vascular endothelial growth factor (VEGF), AQP1 mRNA transcription, protein expression and measured PGE(2), VEGF protein concentration in cell supernatants. Then we treated HUVECs with COX-2 selective inhibitor NS398, EP1/2 combined antagonist AH6809 and exogenous PGE(2) to investigate the role of COX-2/PGE(2) signalling in the angiogenic response of ECs to hypoxia. The results demonstrated that short-term hypoxic treatment enhanced HUVECs proliferation, migration, tube formation, significantly up-regulated COX-2, VEGF, AQP1 mRNA level, protein expression and promoted PGE(2) , VEGF release. The pharmacological inhibition study revealed that exposure of HUVEC to NS398 and AH6809 under hypoxia impaired the biological responses of ECs to hypoxia. Exogenous PGE(2) augments the effects of hypoxia on HUVECs, and partially reversed the inhibitory effects of NS398 on HUVECs proliferation and angiogenic capability. Short-term hypoxic treatment enhanced angiogenic capability of ECs, and COX-2/PGE(2) signalling may play a critical role in the biological response of ECs to hypoxia.

Efficiency of low-level laser therapy in reducing pain induced by orthodontic forces

OBJECTIVE

The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on reducing post-adjustment orthodontic pain via evaluation of gingival crevicular fluid (GCF) composition changes at the level of prostaglandin-E(2) (PGE(2)) and visual analogue scale (VAS).

BACKGROUND DATA

LLLT has been found to be effective in pain relief. PGE(2) has the greatest impact on the process of pain signals and can be detected in GCF in order to investigate the response of dental and periodontal tissues in a biochemical manner.

MATERIALS AND METHODS

Nineteen patients (11 females and 8 males; mean age 13.9 years) were included in this study. Maxillary first molars were banded and then a randomly selected first molar at one side was irradiated (λ820 nm; continuous wave; output power: 50 mW; focal spot: 0.0314 cm(2); exposure duration: 5 sec; power density: 1.59 W/cm(2); energy dose: 0.25 J; energy density: 7.96 J/cm(2) for each shot), while the molar at the other side was served as placebo control. The GCF was collected from the gingival crevice of each molar to evaluate PGE(2) levels, before band placement, 1 and 24 h after laser irradiation. Pain intensity was analyzed at 5 min, 1 h, and 24 h after band placement by using VAS.

RESULTS

Although no difference was found in pain perception at 5 min and 1 h, significant reduction was observed with laser treatment 24 h after application (p<0.05). The mean PGE(2) levels were significantly elevated in control group, whereas a gradual decrease occurred in laser group. The difference in PGE(2) levels at both 1 and 24 h were statistically significant between two groups (p<0.05).

CONCLUSIONS

The significant reductions in both pain intensity and PGE(2) levels revealed that LLLT was efficient in reducing orthodontic post-adjustment pain.

Myeloperoxidase activity is increased in gingival crevicular fluid and whole saliva after fixed orthodontic appliance activation

INTRODUCTION

Orthodontic tooth movement uses mechanical forces that result in inflammation in the first days. Myeloperoxidase (MPO) is an enzyme found in polymorphonuclear neutrophil (PMN) granules, and it is used to estimate the number of PMN granules in tissues. So far, MPO has not been used to study the inflammatory alterations after the application of orthodontic tooth movement forces. The aim of this study was to determine MPO activity in the gingival crevicular fluid (GCF) and saliva (whole stimulated saliva) of orthodontic patients at different time points after fixed appliance activation.

METHODS

MPO was determined in the GCF and collected by means of periopaper from the saliva of 14 patients with orthodontic fixed appliances. GCF and saliva samples were collected at baseline, 2 hours, and 7 and 14 days after application of the orthodontic force.

RESULTS

Mean MPO activity was increased in both the GCF and saliva of orthodontic patients at 2 hours after appliance activation (P <0.02 for all comparisons). At 2 hours, PMN infiltration into the periodontal ligament from the orthodontic force probably results in the increased MPO level observed at this time point.

CONCLUSIONS

MPO might be a good marker to assess inflammation in orthodontic movement; it deserves further studies in orthodontic therapy.

Comparison of levels of inflammatory mediators IL-1beta and betaG in gingival crevicular fluid from molars, premolars, and incisors during rapid palatal expansion

INTRODUCTION

Previously, we reported fluctuation of the levels of the inflammatory mediators interleukin-1beta (IotaL-1beta) and beta-glucuronidase (betaG) in gingival crevicular fluid (GCF) from the maxillary first molars in adolescents undergoing rapid palatal expansion. In this study, we compared the responses of IL-1beta and betaG in the GCF of the maxillary first molars, first premolars, and central incisors during palatal expansion at the same patients.

METHODS

Nine patients requiring palatal expansion were selected at the postdoctoral orthodontic clinic at Columbia University College of Dental Medicine. Each patient received periodontal prophylaxis and instructions in proper home care including rinsing with chlorhexidine. Four weeks after periodontal prophylaxis, a modified hyrax appliance was placed. The jackscrew was activated twice daily until the appropriate expansion was achieved. GCF samples were collected before and after periodontal prophylaxis and during passive wearing of the appliance, active orthodontic treatment, and retention. Fluid samples were collected with filter paper strips and analyzed by ELISA and time-dependent fluorometry for IL-1beta and betaG, respectively. The values recorded after periodontal prophylaxis were used as the baseline. Paired t tests were used to compare mediator levels at baseline with the levels obtained at each subsequent observation.

RESULTS

The results validate that IL-1beta and betaG are present in the GCF of adolescents, and, although their level decreases after a strict regimen of plaque control, it increases during orthodontic or orthopedic movement. Moreover, this study demonstrates that both heavy and light forces evoke increased levels of IL-1beta and betaG, stronger forces cause higher levels of inflammatory mediators, and both IL-1beta and betaG respond to direct and indirect application of mechanical force to teeth.

CONCLUSIONS

This investigation corroborates previous findings that an inflammatory process occurs during application of mechanical force to teeth. Although this inflammation is considered relatively aseptic, additional inflammation, such as that induced by plaque accumulation, must be avoided during orthodontic or orthopedic treatment.

Tumor Necrosis Factor–α Levels during Two Different Canine Distalization Techniques

Objectives: To compare levels of tumor necrosis factor (TNF)-α while applying continuous and heavy interrupted forces.

Materials and Methods: A hybrid retractor was used in the first group. In the second group, rapid canine distalization through periodontal distraction was performed. Gingival crevicular fluid samples were collected from the distal sides of the canine teeth before attaching the appliances and at 1 hour, 24 hours, and 1 week after the force was applied.

Results: In the hybrid reactor group, concentration of TNF-α decreased at 1 week according to 24-hour measurements. In the rapid canine distalization group, it severely increased at 1 hour. In the evaluation of between-group differences, significantly higher values were determined in the rapid canine distalization group at 1 hour and 1 week.

Conclusions: Heavy interrupted force induces a rapid release of TNF-α, and the tissue response continues for a longer time period. To avoid the harmful effects of heavy interrupted force, there might be feedback mechanisms that prevent the mediators from increasing excessively.

Speed of tooth movement is related to stress and IL-1 gene polymorphisms

INTRODUCTION

The variables affecting speed of tooth movement are unquantified. In particular, the effects of stress and human biological variations are unknown. Therefore, our objectives in this study were to determine relationships between (1) stress and velocity of tooth translation (v(t)), and (2) interleukin-1 (IL-1) gene cluster polymorphisms, IL-1beta and IL-1 receptor antagonist (IL-1RA) in gingival crevicular fluid (GCF), and v(t).

METHODS

Ten subjects had their maxillary first premolars extracted and cheek wipe samples genotyped. In each subject, a maxillary canine received 26 kPa and the other received 13 or 52 kPa of stress. GCF samples and tooth movements were measured at 9 or 10 visits over 84 days.

RESULTS

Mean v(t) for canines retracted by 13, 26, and 52 kPa were 0.054, 0.072, and 0.064 mm per day, respectively. Faster v(t) was shown from 26 kPa than 13 kPa (P = .015) and 52 kPa (P = .030), with higher IL-1beta/IL-1RA in GCF at experimental relative to control sites, and in subjects with homozygosity for allele 1 (A1,A1) compared with at least 1 copy of A2 (A2+) at IL-1RN(VNTR(86 bp)) (P = .032), and with A2+ compared with A1,A1 at IL-1B(+3954) (P = .051).

CONCLUSIONS

Stress, IL-1beta/IL-1RA in GCF, and IL-1 gene cluster polymorphisms are related to v(t).

Interleukins 2, 6, and 8 levels in human gingival sulcus during orthodontic treatment

INTRODUCTION

The aims of this study were to determine levels of interleukins 2, 6, and 8 during tooth movement, and test whether they differ from each other with leveling and distalization forces used in various treatment stages of standard orthodontic therapy.

METHODS

Fifteen patients (9 female, 6 male; ages, 15-19 years; mean age, 16.7 +/- 2.3 years) participated in this study. Each underwent a session of professional oral hygiene and received oral hygiene instructions. Two months later, a fixed orthodontic appliance was placed. The patients were seen at baseline, at days 7 and 21, and as the teeth were leveled. Records of the baseline scores for the distalization forces were taken at the sixth month. Scores of days 7 and 21 after 6 months of the distalization treatment were also recorded.

RESULTS

Increases were seen in the volume of gingival crevicular fluid and the concentrations of interleukins 2, 6, and 8.

CONCLUSIONS

Leveling and distalization of the teeth evoke increases in interleukins 2, 6, and 8 levels in the periodontal tissues that can be detected in gingival crevicular fluid.

The effect of gingival retraction procedures on periodontal indices and crevicular fluid cytokine levels: a pilot study

PURPOSE

The purpose of this study was to examine the effects of placement of retraction cord subgingivally upon periodontal indices including plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP), and attachment level (AL), as well as gingival crevicular fluid (GCF) and TNF-alpha levels.

METHODS

Ten teeth in 6 patients who were periodontally healthy were selected. These teeth had pocket depths of 3 mm or less, no evidence of significant loss of attachment, BOP, or plaque accumulation. The patients each received an oral prophylaxis. The following week, baseline measurements of periodontal indices and TNF-alpha were taken and the retraction cord was placed for 15 minutes. Following removal, the patients were dismissed. The periodontal indices measured included PI, GI, PD, BOP, and AL. In addition, the levels of TNF-alpha in GCF, were investigated. These measurements were made before gingival retraction as a baseline and on the 1st, 3rd, 7th, 14th, and 28th days post retraction.

RESULTS

A repeated measures ANOVA showed that TNF-alpha levels in GCF were significantly increased at all five intervals after gingival retraction compared to the baseline. The mean TNF-alpha level peaked at Day 1 (0.90 +/- 0.62), then declined at Days 3 (0.53 +/- 0.16), 7 (0.43 +/- 0.08), 14 (0.47 +/- 0.10), and 28 (0.43 +/- 0.08) but was still elevated 54% above baseline at Day 28, p < 0.01. The GI was significantly elevated at Day 1 (0.9 +/- 0.49), p < 0.01; Day 3 (0.53 +/- 0.32); and Day 7 (0.33 +/- 0.33), p < 0.05. Unlike TNF-alpha, GI recovered to the baseline by day 14. Other periodontal parameters, PI, PD, BOP, and AL were not significantly altered by the gingival retraction procedure.

CONCLUSION

This pilot study supports the previous research that gingival retraction causes an acute injury that heals clinically in 2 weeks as is indicated by the GI. It also provides the first evidence that gingival retraction results in an elevation of the proinflammatory cytokine, TNF-alpha, in GCF.

Pain Discomfort and Crevicular Fluid Changes Induced by Orthodontic Elastic Separators in Children

The objective of the present investigation was to study the experience of pain after placement of orthodontic elastic separators and the possible associations with the gingival crevicular fluid (GCF) composition changes at the level of interleukin 1-beta (IL-1beta), substance P (SP), and prostaglandin-E2 (PGE2). Eighteen children (mean age 10.8 yrs) in the beginning of the orthodontic treatment were included. Molar elastic separators were inserted mesially to 2 first upper or lower molars. One of the antagonist molars served as control. The GCF was collected from the distobuccal and distopalatal sites from each molar, before (day -7, day 0) and after the placement of separators (1 h, day 1, and day 7). Pain intensity was recorded using a visual analog scale (VAS). The contents of IL-1beta, SP, and PGE2 were determined by enzyme-linked immunosorbent assay. Pain intensity increased after 1 h (VAS = 11) and remained high on day 1 (VAS = 13). On day 7, no significant pain was reported. After 1 h, 1 day, and 7 days, mean GCF IL-1beta levels were significantly elevated at treatment teeth compared to control teeth (highest day 1). The GCF levels of SP and PGE2 for the treatment teeth were significantly higher at day 1 and day 7 than the control teeth. All 3 mediators remained at baseline levels throughout the experiment for the control teeth. The intensity of pain at 1 h was associated to PGE2 levels (R2 = 0.38; P < .05), whereas at day 1, the intensity of pain was associated to IL-1beta levels (R2 = 0.63, P < .0001). Thus, we report a rapid release of biochemical markers (1 h) that peaked after 1 day and partially decreased 7 days later. The intensity of pain followed a similar pattern. Associations were found between the experience of pain intensity and the GCF mediator levels.

PERSPECTIVE

The study may help to detect, in an initial stage, individuals prone to perceive higher level of pain during orthodontic treatment. This may help in the development of methods that will better control and/or alleviate the discomfort of pain during tooth movement.

Tooth movement and cytokines in gingival crevicular fluid and whole blood in growing and adult subjects

INTRODUCTION

Tooth movement has been studied largely with respect to the force required for tipping when pressure distribution varies along the length of the periodontal ligament. But important factors for effective canine translation include the nature and magnitude of applied stress and the patient's cell biology. The purpose of this research was to test 3 hypotheses: (1) the velocity of tooth translation (v(t)) is related to applied stress and growth status, (2) a threshold of stress accounts for the lag phase, and (3) v(t) is correlated with the ratio (AI) of 2 cytokines (IL-1beta, IL-1RA) measured in gingival crevicular fluid (GCF) and stimulated whole blood (SWB).

METHODS

Continuous maxillary canine retraction stresses of 13 kPa and 4, 26, or 52 kPa were applied bilaterally in 6 growing and 4 adult subjects for 84 days. Dental models and GCF samples were collected at 1- to 14-day intervals. Cytokines were measured in GCF and SWB cell cultures.

RESULTS

V(t) was positively related to stress and was higher in growing subjects (P = .001). It was also related to AI(GCF) in growers (R2= 0.56) and nongrowers (R2= 0.72). Canines moved with 52 kPa showed a lag phase, and postlag phase AI(GCF) was twice that of lag phase AI(GCF). Mean v(t) and associated AI(GCF) during the postlag phase were nearly double the values for canines moved with 13 and 26 kPa. SWB production of cytokines was dose-dependent. For growing subjects, SWB IL-1RA was correlated with v(t) (R = 0.70-0.72), and AI(SWB) and IL-1beta concentrations were correlated with AI(GCF) (R = 0.73-0.78).

CONCLUSIONS

V(t) varied with growth status and stresses < or = 52 kPa; stresses of < 52 kPa showed no lag phase; and equivalent stresses yielded subject-dependent differences in v(t), which correlated with cytokines in GCF and SWB.

Effects of continuous and interrupted orthodontic force on interleukin-1beta and prostaglandin E2 production in gingival crevicular fluid

The purpose of this study was to evaluate the effects of a light continuous force and an interrupted force with weekly reactivation on interleukin-1beta (IL-1beta) and prostaglandin E(2) (PGE(2)); possible interactions between these 2 potent mediators of the bone resorption process were assessed in vivo. Ten healthy young adults (mean age 20.6 years, 2 men, 8 women) with 4 premolars extracted were assessed. In each subject, 1 maxillary canine (E1) received continuous force with a nickel-titanium coil spring. The opposite canine (E2) received an interrupted force with a screw-attached retractor; the force was reactivated weekly by 2 turns of the screw. An antagonistic canine was used as a control. Gingival crevicular fluid was collected from the distal side of each tooth, 10 times in 3 weeks, and IL-1beta and PGE(2) levels were measured. For E1, the IL-1beta level showed a significant elevation at 24 hours and then decreased and maintained an insignificant but high mean concentration, compared with the control site. The PGE(2) level showed a significant elevation at 24 hours and then decreased. For E2, a significant elevation of IL-1beta level was observed at 24 hours and a greater significant elevation at 24 hours after the first reactivation, compared with the control sites. The PGE(2) level increased significantly at 24 hours and remained high for 1 week. The synergistic up-regulation of PGE(2) by appliance reactivation and secreted IL-1beta was not evident with either type of force after 1 week. Both experimental sites showed significant tooth movement compared with the control sites at 3 weeks; however, there was no significant difference between the 2 experimental sites. A well-controlled mechanical stress with timely reactivation can effectively upregulate IL-1beta secretion, but there might be limitations in increasing the mediator levels, because of the feedback mechanisms in vivo. In addition, the analysis of crevicular fluid is a useful method for assessing cellular response to orthodontic force in vivo.

Impact of Increased Occlusal Contact, Interleukin-1 Genotype, and Periodontitis Severity on Gingival Crevicular Fluid IL-1β Levels

BACKGROUND

The study of occlusal therapy in humans with periodontitis is problematic due to potential irreversible bone loss in control subjects. The hypothesis of this pilot investigation was that increased interocclusal contact initiated by short-term occlusal splint disuse would increase tooth mobility and the bone-resorptive cytokine interleukin (IL)-1beta in gingival crevicular fluid (GCF), comparable to IL-1-positive genotype and increased periodontitis severity.

METHODS

Nineteen non-smoking chronic periodontitis patients using nocturnal occlusal splints and undergoing periodontal maintenance in a private practice were evaluated at five time points: 24 hours after continuous splint use; 1, 2, and 3 days after no occlusal splint use; and 14 days after resumption of customary nighttime splint use. Subjects were evaluated to confirm that the plaque index and gingival index were < or = 1.0, and to categorize past periodontitis (moderate or severe) and IL-1 genotype (1A +4845 plus IL-1B +3954). Test sites on two anterior teeth vulnerable to occlusal trauma were sampled for mobility, GCF IL-1beta, and IL-1 receptor antagonist (ra).

RESULTS

Tooth mobility remained low during the 3-day period when patients were not wearing their occlusal appliance. GCF IL-1beta decreased after not wearing the appliances (P = 0.016), especially at 48 hours. At this time, genotype-positive subjects had higher levels of GCF IL-1beta/IL-1ra than genotype-negative subjects (P = 0.045), and patients who had experienced severe periodontitis had higher IL-1beta levels than moderate periodontitis subjects (P = 0.004).

CONCLUSIONS

These findings suggest that short-term discontinuation of occlusal splint therapy in non-smoking periodontitis patients undergoing periodontal maintenance does not result in potential signs of early occlusal trauma (increasing mobility or GCF IL-1beta). Longer-term studies may be needed to determine appropriate therapy applications for periodontitis-susceptible patients with definable occlusal discrepancies and/or parafunction.

Genetic predisposition to external apical root resorption

External apical root resorption (EARR) can be an undesirable sequela of orthodontic treatment. Previous studies have suggested that EARR has a substantial genetic component. Linkage and association were examined between polymorphisms of the interleukin IL-1 (IL-1A and IL-1B) genes and EARR in 35 white American families. Buccal swab cells were collected for DNA isolation and analysis. The EARR in the maxillary central incisors, the mandibular central incisors, and the mesial and distal roots of the mandibular first molar were analyzed separately and together by using both linkage and association methods of analysis. Highly significant (P =.0003) evidence of linkage disequilibrium of IL-1B polymorphism with the clinical manifestation of EARR was obtained. The analysis indicates that the IL-1B polymorphism accounts for 15% of the total variation of maxillary incisor EARR. Persons homozygous for the IL-1B allele 1 have a 5.6 fold (95% CI 1.9-21.2) increased risk of EARR greater than 2 mm as compared with those who are not homozygous for the IL-1 beta allele 1. Data indicate that allele 1 at the IL-1B gene, known to decrease the production of IL-1 cytokine in vivo, significantly increases the risk of EARR. These findings are consistent with an interpretation of EARR as a complex condition influenced by many factors, with the IL-1B gene contributing an important predisposition to this common problem. Defining genetic contributions to EARR is an important factor in understanding the contribution of environmental factors, such as habits and therapeutic biomechanics.

Human interleukin-1 beta and interleukin-1 receptor antagonist secretion and velocity of tooth movement

The cytokines interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1RA) probably play a part in orthodontic tooth movement. Here, the force magnitudes and the area of force application in the compressed periodontal ligament (PDL) were controlled and the velocity of tooth movement correlated with concentrations of IL-1 beta and IL-1RA in the gingival crevicular fluid (GCF). Seven individuals undergoing orthodontic treatment involving maxillary first premolar extractions and distal movement (bodily retraction) of the maxillary canines participated in the 84-day study. For each participant, continuous retraction forces were applied so that they received equivalent PDL stresses of 13 kPa for one canine and 4 kPa for the other. GCF cytokine concentrations from experimental and control teeth were expressed relative to total protein in the GCF and compared using an 'Activity Index' (AI)=Experimental (IL-1 beta/IL-1RA)/Control (IL-1 beta/IL-1RA). The results showed that the velocity of tooth movement in an individual was related to their AI. The correlation between AI and tooth movement was stronger from the distal (R(d)=0.78) than from the mesial (R(m)=0.65) of retracted teeth. The results demonstrate that equivalent force systems produce individual differences in cytokine production, which correlate with interindividual differences in the velocity of canine retraction.