Aspartate aminotransferase activity in gingival crevicular fluid during orthodontic treatment. A controlled short-term longitudinal study

Adverse effects of orthodontic forces on dental pulp. Appearance and character. A systematic review

OBJECTIVE

To comprehensively assess recent data on the effects of orthodontic forces on the dental pulp and to critically evaluate, whether any of the changes are permanent.

MATERIALS AND METHODS

Articles published between 2/2009 and 2/2022 were searched electronically on the PubMed, EMBASE and SCOPUS databases. The initial search retrieved 780 publications and, applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 33 relevant articles were identified. Twenty articles fulfilled the requirements for high (n = 1) or moderate (n = 19) methodological quality and were included. All assessments were made independently by three researchers.

RESULTS

Orthodontic forces appeared to cause a reduction in pulpal blood flow and a reduction in tooth sensibility, as indicated by increased response thresholds and increased amounts of negative responses to tooth sensibility tests. In addition, there were increases in the expression or activity levels of enzymes and neuropeptides associated with hypoxia and inflammation. Fibrotic tissue formation in the pulp was also reported.

CONCLUSIONS

Except for some histological and morphological alterations, the observed pulpal changes were in most cases only temporary, appearing within days of initiating the treatment and usually lasting for weeks. There were no clear signs of permanent damage.

Comparison of the efficacy of different periodic periodontal scaling protocols for oral hygiene in adolescents with fixed orthodontic appliances: A prospective cohort study

INTRODUCTION

The purpose of this reseach was to compare the effects of different periodic periodontal scaling protocols on the periodontal health of adolescents with fixed orthodontic appliances by assessing the aspartate aminotransferase (AST) and alkaline phosphatase (ALP) levels in gingival crevicular fluid and periodontal clinical indexes in a prospective cohort study.

METHODS

Forty-eight adolescents were divided into 3 groups according to the interval of periodontal scaling (group A: once a month; group B: once every 3 months; group C: once every 6 months). The AST and ALP levels in the gingival crevicular fluid were measured before orthodontic treatment (T₀) and at 1 (T₁), 3 (T₂), 6 (T₃), and 9 (T₄) months during orthodontic treatment. Periodontal clinical indexes (plaque index [PI], gingival index [GI], and probing depth) were also assessed.

RESULTS

At T₂, significantly lower AST and ALP levels were observed in group A than in groups B and C (P <0.05). At T₃ and T₄, lower AST and ALP levels were detected in groups A and B than in group C (P <0.05), and there was no significant difference between the A and B groups at T₄ (P >0.05). At T₂, the PI and GI were increased in groups B and C compared with group A, and at T₃ and T₄, significantly lower PI and GI values were observed in groups A and B than in group C (P <0.05).

CONCLUSIONS

Periodontal scaling promotes the oral hygiene of adolescents undergoing fixed orthodontic treatment, and periodontal scaling protocols administered monthly and once every 3 months are better for controlling periodontal health than treatments administered once every 6 months.

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.

A preliminary investigation of short-term cytokine expression in gingival crevicular fluid secondary to high-level orthodontic forces and the associated root resorption: case series analytical study

BACKGROUND

Orthodontically induced iatrogenic root resorption (OIIRR) is an unavoidable inflammatory process. Several factors claimed to be related to the severity of OIIRR. Orthodontic forces cause micro-trauma to the periodontal ligament and activate a cascade of cellular events associated with local periodontal inflammation. The purpose of this split-mouth study were (1) to investigate the changes in cytokine profile in the gingival crevicular fluid (GCF) secondary to heavy orthodontic forces and (2) to compare the cytokine expression between participants showing high and low root resorption.

METHODS

Eight participants requiring maxillary first premolar extractions involved in this study. The teeth on the tested side (TS) received 225 g of controlled buccal tipping force for 28 days, while the contralateral teeth act as a control (CS). GCF was collected from both TS and CS teeth at 0 h (prior to application of force) and 3 h, 1 day, 3 days, 7 days and 28 days after the application of force, and analysed with multiplex bead immunoassay to determine the cytokine levels.

RESULTS

Statistically significant temporal increase was found in the TS teeth for tumour necrosis factor alpha (TNF-α) at 3 h and 28 days (p = 0.01). Interleukin 7 (IL-7) significantly peaked at the 28th day. Comparing cytokine profile for participants with high and low root resorption (>0.35 and <0.15 mm3, respectively), the levels of GM-CSF was significantly greater in low root resorption cases (p < 0.05). The amounts of root resorption which craters on mesial, distal surfaces and middle third region were significant in the TS teeth (p < 0.05).

CONCLUSIONS

IL-7 and TNF-α (pro-resorptive cytokine) increased significantly secondary to a high-level of orthodontic force application. Significantly high levels of granulocyte macrophage colony-stimulating factor (anti-resorptive cytokine) were detected in mild root resorption cases secondary to high-level orthodontic force application. A future long-term randomised clinical trial with larger sample taking in consideration gender, age and growth pattern distribution would be recommended.

Markers in blood and saliva for prediction of orthodontically induced inflammatory root resorption: a retrospective case controlled-study

BACKGROUND

Hormonal and enzymatic factors may render certain individuals more susceptible to orthodontically induced inflammatory root resorption (OIIRR). The objectives of this study are (1) to identify biochemical key markers in blood and saliva that may be correlated to the trend of extensive OIIRR and (2) to utilise these markers to predict a susceptible patient-receiving orthodontic treatment.

METHODS

Nine patients (mean age 23 + 2.9 years) who had moderate to severe OIIRR that assessed via orthopantomograms and met the inclusion criteria were classified as the root resorption group (RRG). Blood chemistry was evaluated using the collection of fasting blood and unstimulated saliva samples. Multiplex enzyme-linked immunosorbent assay (ELISA) arrays were used to screen blood and saliva samples for human cytokines, chemokines and several key enzymes that may play a role in root resorption following orthodontic force application. Biochemical findings from 16 matching subjects were used as the control (CG) for comparative measurements.

RESULTS

Patients with moderate to severe OIIRR showed a significant increase in salivary cytokines including interleukin (IL) 7, IL-10, IL-12p70 and interferon-gamma (IFN-γ) level as well as a significant decrease in IL-4 level. Osteocalcin and procollagen type I N-terminal peptide (P1NP) appeared to be the only blood factors that showed a significant difference, more in the CG than the RRG.

CONCLUSIONS

Saliva might be a more valuable way of measuring changes in cytokine expression than blood secondary to orthodontic treatment. Although the increased expression of pro-inflammatory and anti-inflammatory cytokines may be determinants in the development of moderate to severe OIIRR, cytokine expression may be affected by several potential inflammations in another part of the body. Future research could investigate the cause/effect relationship of different cytokines, in a larger group of patients and at different time intervals, using digital subtraction radiography techniques and microfluidic biosensors.

Comparative evaluation of pentraxin 3 levels in GCF during canine retraction with active tieback and NiTi coil spring: An in vivo study

Objectives:

To compare the levels of pentraxin 3 (PTX-3) in gingival crevicular fluid (GCF) in patients undergoing orthodontic canine retraction with active tieback and nickel titanium (NiTi) coil spring.

Materials and Methods:

Fifteen patients of the age group 15–25 years with first premolar extraction undergoing canine retraction were selected. One month after placement of 0.019” × 0.025” stainless steel wire, canine retraction was started with active tieback (150 g force) on upper right quadrant and NiTi coil spring (150 g force) on upper left quadrant. GCF samples were collected 1 h before commencement of canine retraction and thereafter at intervals of 1 h, 1 day, 1 week, and 2 weeks after application of force. The collected GCF was eluted from the microcapillary pipette in 100 μl phosphate-buffered saline (pH 5–7.2). The samples were analyzed for PTX-3 levels by the ELISA technique.

Results:

The mean levels of PTX-3 at 1 h before canine retraction (baseline) was 1.30 ± 0.22 ng/ml and at 1 h 1.66 ± 0.33 ng/ml, 1 day 2.65 ± 0.09 ng/ml, 1 week 1.96 ± 0.15 ng/ml, and 2 weeks 1.37 ± 0.18 ng/ml in active tieback group. The mean levels of PTX-3 at 1 h before canine retraction was 1.32 ± 0.30 ng/ml, and at 1 h 1.71 ± 0.39 ng/ml, 1 day 2.78 ± 0.12 ng/ml, 1 week 2.52 ± 0.18 ng/ml, and 2 weeks 2.12 ± 0.17 ng/ml in NiTi coil spring group. A significant difference of P < 0.001 was found in PTX-3 levels in GCF during canine retraction between active tieback and NiTi coil spring at 1 day, 1 week, and 2 weeks.

Conclusion:

The results showed that PTX-3 levels increased from 1 h after application of orthodontic force and reached peak at 1 day, followed by a gradual decrease at 1 week and 2 weeks in both active tie back and NiTi coil spring groups.

Biomarkers in orthodontic tooth movement

Tooth movement by orthodontic treatment is characterized by remodeling changes in the periodontal ligament, alveolar bone, and gingiva. A reflection of these phenomenons can be found in the gingival crevicular fluid (GCF) of moving teeth, with significant elevations in the concentrations of its components like, cytokines, neurotransmitters, growth Factors, and a arachidonic acid metabolites. GCF arises at the gingival margin and can be described as a transudate or an exudate. Several studies have focused on the composition of GCF and the changes that occur during orthodontic tooth movement (OTM). GCF component analysis is a non-invasive method for studying the cellular response of the underlying periodontium. Clinically, GCF can be easily collected using platinum loops, filter paper strips, gingival washings, and micropipettes. A number of GCF biomarkers involve in bone remodeling during OTM. The data suggest that knowledge of all the biomarkers present in the GCF that can be used to mark the changes in tooth that is undergoing orthodontic treatment may be of clinical usefulness leading to proper choice of mechanical stress to improve and to shorten treatment time and avoid side effects.

Aspartate aminotransferase activity in the pulp of teeth treated for 6 months with fixed orthodontic appliances

Objective

To measure aspartate aminotransferase (AST) activity in the pulp of teeth treated with fixed appliances for 6 months, and compare it with AST activity measured in untreated teeth.

Methods

The study sample consisted of 16 healthy subjects (mean age 25.7 ± 4.3 years) who required the extraction of maxillary premolars for orthodontic reasons. Of these, 6 individuals had a total of 11 sound teeth extracted without any orthodontic treatment (the control group), and 10 individuals had a total of 20 sound teeth extracted after 6 months of orthodontic alignment (the experimental group). Dental pulp samples were extracted from all control and experimental teeth, and the AST activity exhibited by these samples was determined spectrophotometrically at 20℃.

Results

Mean AST values were 25.29 × 10^-5 U/mg (standard deviation [SD] 9.95) in the control group and 27.54 × 10^-5 U/mg (SD 31.81) in the experimental group. The difference between these means was not statistically significantly (p = 0.778), and the distribution of the AST values was also similar in both groups.

Conclusions

No statistically significant increase in AST activity in the pulp of mechanically loaded teeth was detected after 6 months of orthodontic alignment, as compared to that of teeth extracted from individuals who had not undergone orthodontic treatment. This suggests that time-related regenerative processes occur in the dental pulp.

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.

Levels of matrix metalloproteinase-7 and osteopontin in human gingival crevicular fluid during initial tooth movement

Purpose

During orthodontic treatment, the early response of periodontal tissues to mechanical stress involves several metabolic changes that allow tooth movement. The purpose of this investigation was to evaluate osteopontin (OPN) and matrix metalloproteinase (MMP)-7 in the gingival crevicular fluid (GCF) of human teeth exposed to orthodontic force.

Materials and Methods

GCF samples were obtained from 15 healthy orthodontic patients (age, 12-22 years). In each patient, the left maxillary canine having the fixed orthodontic appliance was used as the test tooth, and its antagonist, with no appliance, was the control. Orthodontic force, 75 g was applied using a 16 × 22 beta titanium closing loop. The GCF sampling on the disto-buccal aspects of experimental and control tooth was performed at specific time interval with sterilized absorbent paper point. Processing was carried out with enzyme-linked immunosorbent assay to detect OPN and MMP-7 levels.

Results

The peak level of OPN was seen after 1 h application of orthodontic force which was 1280.36 pg/ml ± 185.02. The peak level of MMP-7 was seen at 0 h which was 598.3 pg/ml ± 107.5. The levels of OPN after 1 h increased to 1280.36 pg/ml ± 185.02, and they decreased at 24 h to 1012.86 pg/ml ± 168.47 (P= 0.001). The levels of MMP-7 after 1 h decreased to 478 pg/ml ± 99.7 which increased at 24 h to 526.9 pg/ml ± 99.2.

Conclusions

Orthodontic forces affect both OPN and MMP-7 protein levels on the compression side in a time-dependent fashion.

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.

Enzymatic evaluation of gingival crevicular fluid in cleft palate patients during orthodontic treatment: A clinico-biochemical study

Background:

Therapeutic goal in patients with cleft lip and palate is esthetics and long-term health of the stomatognathic system. Patients with cleft lip and palate routinely require extensive and prolonged orthodontic treatment. The osseous structures are absent or poorly developed in the osseous clefts and may be traumatized in the course of orthodontic therapy; hence require constant monitoring during orthodontic treatment. The aim of the study was to evaluate the tissue response of cleft palate patients by quantitative analysis of enzyme activity during orthodontic treatment and assess any difference in the tissue response with that of noncleft patients undergoing orthodontic treatment.

Materials and Methods:

20 patients requiring orthodontic treatment agedbetween 15 to 25 years were included to participate in the studyof which ten were cleft palate patients (group I) and ten noncleft patients (group II). The GCF samples were collected at incisor and molar sites during orthodontic treatment on days as per the study design in both the groups. The GCF enzymatic levels were estimated and compared.

Results:

Both groups showed significant increased enzyme activity at the incisor site compared to molar site corresponding to the phases of tooth movement.

Conclusion:

There was significant difference in enzyme activity between the incisor adjacent to the cleft site and molar site. There was no difference in the tissue response between cleft palate patients and noncleft patients during orthodontic treatment.

Cellular response within the periodontal ligament on application of orthodontic forces

During application of controlled orthodontic force on teeth, remodeling of the periodontal ligament (PDL) and the alveolar bone takes place. Orthodontic forces induce a multifaceted bone remodeling response. Osteoclasts responsible for bone resorption are mainly derived from the macrophages and osteoblasts are produced by proliferations of the cells of the periodontal ligament. Orthodontic force produces local alterations in vascularity, as well as cellular and extracellular matrix reorganization, leading to the synthesis and release of various neurotransmitters, cytokines, growth factors, colony-stimulating factors, and metabolites of arachidonic acid. Although many studies have been reported in the orthodontic and related scientific literature, research is constantly being done in this field resulting in numerous current updates in the biology of tooth movement, in response to orthodontic force. Therefore, the aim of this review is to describe the mechanical and biological processes taking place at the cellular level during orthodontic tooth movement.

Biomarkers of periodontal tissue remodeling during orthodontic tooth movement in mice and men: overview and clinical relevance

Biologically active substances are expressed by cells within the periodontium in response to mechanical stimuli from orthodontic appliances. Several possible biomarkers representing biological modifications during specific phenomena as simile-inflammatory process, bone resorption and formation, periodontal ligament changes, and vascular and neural responses are proposed. Citations to potentially published trials were conducted by searching PubMed, Cochrane databases, and scientific textbooks. Additionally, hand searching and contact with experts in the area were undertaken to identify potentially relevant published and unpublished studies. Selection criteria were as follows: animal models involving only mice and rats undergoing orthodontic treatment; collection of gingival crevicular fluid (GCF) as a noninvasively procedure for humans; no other simultaneous treatment that could affect experimental orthodontic movement. The data suggest that knowledge of the remodeling process occurring in periodontal tissues during orthodontic and orthopedic therapies may be a clinical usefulness procedure leading to proper choice of mechanical stress to improve and to shorten the period of treatment, avoiding adverse consequences. The relevance for clinicians of evaluating the rate of some substances as valid biomarkers of periodontal effects during orthodontic movement, by means of two models of study, mice and men, is underlined.

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.

Gingival crevicular fluid protein content and alkaline phosphatase activity in relation to pubertal growth phase

OBJECTIVE

To evaluate gingival crevicular fluid (GCF) protein content and alkaline phosphatase (ALP) activity in growing subjects in relation to stages of skeletal maturation, ie, the growth phase, as prepubertal, pubertal, and postpubertal.

SUBJECTS AND METHODS

Fifty healthy growing subjects (31 girls and 19 boys; age range, 7.8-17.7 years) were enrolled in this study that followed a double-blind, prospective, cross-sectional design. Collection of GCF was performed at the mesial and distal sites of both central incisors, for the maxilla and mandible. Growth phase was assessed through the cervical vertebral maturation method. GCF parameters were expressed as total protein content, total ALP activity, and normalized ALP activity.

RESULTS

The total GCF protein content was similar between the different growth phases. On the contrary, the total ALP activity showed a peak for the pubertal growth phase. The normalized GCF ALP activity was only poorly associated with growth phase. No differences were seen between the maxillary and mandibular sites, or between the sexes, for any GCF parameter.

CONCLUSIONS

The total GCF protein content is not sensitive to the growth phase. However, GCF ALP activity has potential as a diagnostic aid for identification of the pubertal growth phase in individual subjects when expressed as total, but not normalized, values.

Repeatability of gingival crevicular fluid collection and quantification, as determined through its alkaline phosphatase activity: implications for diagnostic use

BACKGROUND AND OBJECTIVE

In spite of four decades of studies on gingival crevicular fluid, no data have been reported on the repeatability of gingival crevicular fluid collection and the subsequent quantification procedures. The present study reports, for the first time, on the repeatability and method error of gingival crevicular fluid collection and quantification, as determined through its alkaline phosphatase (ALP) activity. Diagnostic considerations are then explored.

MATERIAL AND METHODS

Twenty-seven healthy subjects (17 women and 10 men; mean age ± SD, 21.2 ± 4.8 years) with optimal periodontal status were enrolled according to a blind prospective design. The gingival crevicular fluid was collected at baseline, and after 1 d, 1 wk and 3 mo. At each clinical session, two consecutive rounds of gingival crevicular fluid collection were made from each of the four maxillary incisors, allowing the recovery of resting and flow gingival crevicular fluid. The total ALP activities were determined spectrophotometrically, and repeatability and method errors for the resting, flow and overall (resting + flow) gingival crevicular fluid ALP activities were calculated, relative to the corresponding baseline levels.

RESULTS

No significant differences were seen over time, although the flow gingival crevicular fluid ALP activity was generally lower than that for the resting gingival crevicular fluid. The method errors ranged from 40 to 58%, with the flow and overall gingival crevicular fluid activities showing the highest and lowest errors, respectively.

CONCLUSION

Reliable use of the gingival crevicular fluid ALP collection and quantification, both in research and diagnosis on an individual basis, should take into account relevant errors, and variations are to be considered as true only above relevant thresholds.

Pentraxin-3 levels in gingival crevicular fluid during orthodontic tooth movement in young and adult patients

OBJECTIVES

To measure the levels of pentraxin-3 (PTX-3) in gingival crevicular fluid (GCF) in orthodontic young and adult patients in the first 2 weeks after the orthodontic appliance to determine whether those changes occur during orthodontic treatment and if those values could be the expression of an inflammatory state.

MATERIALS AND METHODS

GCF samples were collected with paper strips from 16 orthodontic young patients and 13 orthodontic adult patients from an upper canine requiring distalization as a test tooth. A contralateral canine was used as a control tooth. The absorbed volume was eluted in 100 µL phosphate-buffered saline (pH  =  7.2). PTX-3 levels in GCF were determined using a commercial enzyme-linked immunosorbent assay kit, and the results were expressed in ng/mL.

RESULTS

The results showed an increase of GCF levels of PTX-3 from 1 hour before the orthodontic appliance to a maximum at 24 hours, followed by a decrease in both groups of adult and young patients.

CONCLUSIONS

The results suggest PTX-3 involvement in periodontal orthodontic remodeling and the aseptic inflammation induced by the orthodontic forces.

Cellular and molecular changes in orthodontic tooth movement

Tooth movement induced by orthodontic treatment can cause sequential reactions involving the periodontal tissue and alveolar bone, resulting in the release of numerous substances from the dental tissues and surrounding structures. To better understand the biological processes involved in orthodontic treatment, improve treatment, and reduce adverse side effects, several of these substances have been proposed as biomarkers. Potential biological markers can be collected from different tissue samples, and suitable sampling is important to accurately reflect biological processes. This paper covers the tissue changes that are involved during orthodontic tooth movement such as at compression region (involving osteoblasts), tension region (involving osteoclasts), dental root, and pulp tissues. Besides, the involvement of stem cells and their development towards osteoblasts and osteoclasts during orthodontic treatment have also been explained. Several possible biomarkers representing these biological changes during specific phenomenon, that is, bone remodelling (formation and resorption), inflammation, and root resorption have also been proposed. The knowledge of these biomarkers could be used in accelerating orthodontic treatment.

Gingival crevicular fluid alkaline phosphatase activity as a non-invasive biomarker of skeletal maturation

OBJECTIVES

To evaluate the gingival crevicular fluid (GCF) alkaline phosphatase (ALP) activity in growing subjects in relation to the stages of individual skeletal maturation.

SETTING AND SAMPLE POPULATION

The Department of Biomedicine, University of Trieste. Seventy-two healthy growing subjects (45 women and 27 men; range, 7.8-17.7 years).

MATERIALS AND METHODS

Double-blind, prospective, cross-sectional design. Samples of GCF were collected from each subject at the mesial and distal sites of both of the central incisors, in the maxilla and mandible. Skeletal maturation phase was assessed through the cervical vertebral maturation (CVM) method. Enzymatic activity was determined spectrophotometrically.

RESULTS

The relationship between GCF ALP activity and CVM stages was significant. In particular, a twofold peak in enzyme activity was seen at the CS3 and CS4 pubertal stages, compared to the pre-pubertal stages (CS1 and CS2) and post-pubertal stages (CS5 and CS6), at both the maxillary and mandibular sites. No differences were seen between the maxillary and mandibular sites, or between the sexes.

CONCLUSIONS

As an adjunct to standard methods based upon radiographic parameters, the GCF ALP may be a candidate as a non-invasive clinical biomarker for the identification of the pubertal growth spurt in periodontally healthy subjects scheduled for orthodontic treatment.

Change in dental pulp parameters in response to different modes of orthodontic force application

OBJECTIVES

(1) To evaluate dental pulp sensitivity by electrical pulp testing and measure aspartate aminotransferase activity in the pulp after 14 days of orthodontic intrusion, and (2) to compare those measurements with measurements obtained in teeth after 7 days of intrusion and 7 days of rest.

MATERIALS AND METHODS

The study sample included 13 subjects (mean age = 16.5 +/- 2.7 years). For every subject, before extraction, two contralateral premolars were included in a spring and loaded by a force. Two study groups were formed: Group A, teeth with 14 days of mechanical load, and Group B, teeth with 7 days of mechanical load plus 7 days of rest. Electrical pulp testing and aspartate aminotransferase activity measurements were performed after 14 days in all tested teeth. After extraction, aspartate aminotransferase activity in the pulp was determined spectrophotometrically at 20 degrees C.

RESULTS

Mean aspartate aminotransferase activity values were 0.21 U/mg (SD = 0.15) in Group A and 0.27 U/mg (SD = 0.17) in Group B. Mean electrical pulp testing readings were 38.92 microA (SD = 24.61) in Group A and 36.77 microA (SD = 26.84) in Group B. Mean values of the intrusive force magnitude did not differ in both groups.

CONCLUSIONS

Different durations of orthodontic intrusion, defined as 14 days of load and 7 days of load followed by 7 resting days, were not reflected by electrical pulp testing or by aspartate aminotransferase activity levels in the pulp of the affected teeth. However, the response threshold to electrical pulp stimulation was elevated in all tested teeth.

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.

Cellular, molecular, and tissue-level reactions to orthodontic force

Remodeling changes in paradental tissues are considered essential in effecting orthodontic tooth movement. The force-induced tissue strain produces local alterations in vascularity, as well as cellular and extracellular matrix reorganization, leading to the synthesis and release of various neurotransmitters, cytokines, growth factors, colony-stimulating factors, and metabolites of arachidonic acid. Recent research in the biological basis of tooth movement has provided detailed insight into molecular, cellular, and tissue-level reactions to orthodontic forces. Although many studies have been reported in the orthodontic and related scientific literature, a concise convergence of all data is still lacking. Such an amalgamation of the rapidly accumulating scientific information should help orthodontic clinicians and educators understand the biological processes that underlie the phenomenon of tooth movement with mechanics (removable, fixed, or functional appliances). This review aims to achieve this goal and is organized to include all major findings from the beginning of research in the biology of tooth movement. It highlights recent developments in cellular, molecular, tissue, and genetic reactions in response to orthodontic force application. It reviews briefly the processes of bone, periodontal ligament, and gingival remodeling in response to orthodontic force. This review also provides insight into the biological background of various deleterious effects of orthodontic forces.

Lactate dehydrogenase activity in human gingival crevicular fluid during orthodontic treatment: a controlled, short-term longitudinal study

BACKGROUND

During orthodontic tooth movement, the early response of periodontal tissues to mechanical stress is an acute inflammatory one. This study uses a longitudinal design to examine lactate dehydrogenase (LDH) activity in gingival crevicular fluid (GCF) to determine if GCF LDH can be used as a diagnostic aid in monitoring tooth movement and tissue response during orthodontic treatment.

METHODS

Seventeen patients (mean age: 16.1 years) participated in the study. Each patient was undergoing treatment for distal movement, and an upper first molar served as the test tooth (TT), while the contralateral (CT) and antagonist (AT) teeth were used as controls. The CT was included in the orthodontic appliance, but was not subjected to the distal movement; the AT was free from any orthodontic appliance. The GCF around the experimental teeth was harvested from both mesial and distal tooth sites immediately before appliance activation, and on days 7, 14, and 21. Clinical gingival conditions were also recorded.

RESULTS

Gingival crevicular fluid LDH activity was significantly elevated in all sites of the TT and CT, as compared to the AT, where LDH activity remained at the baseline level throughout the study. Enzyme activity levels were also greater in the TT than in the CT, and in the compression sites.

CONCLUSIONS

Our results suggest that GCF LDH levels reflect the biological activity that takes place in the periodontium during orthodontic movement, and therefore they can be used as a diagnostic tool for monitoring for correct orthodontic tooth movement in clinical practice.

Aspartate aminotransferase activity in pulp of orthodontically treated teeth

This study examines the aspartate aminotransferase activity in the pulp of orthodontically treated teeth. Seventeen healthy male and female subjects (ages: 14.5-19.6; mean 16.8 +/- 1.6 years) who needed extraction of the maxillary first premolars for orthodontic reasons were enrolled in the study. One randomly chosen maxillary first premolar, included in a straight-wire fixed orthodontic appliance and supporting orthodontic force, was considered as the test tooth. The contralateral first premolar, included in the orthodontic appliance but not subjected to mechanical stress, was used as the control tooth. After a week of treatment, the dental pulp tissues were extracted from both experimental teeth. Aspartate aminotransferase activity was significantly elevated in the test teeth as compared with the control teeth. These results demonstrate that in the early phases of treatment, orthodontic force application to the teeth can lead to significant metabolic changes in the pulp of these teeth.

Lactate dehydrogenase activity in gingival crevicular fluid during orthodontic treatment

During orthodontic treatment, the early response of periodontal tissues to mechanical stress involves several metabolic changes that allow tooth movement. Many studies have evaluated such modifications by analysis of various host metabolites released into the gingival crevicular fluid (GCF). This study used a cross-sectional design to examine the lactate dehydrogenase (LDH) activity in GCF to assess whether GCF LDH can be proposed as a sensitive marker for periodontal tissue modifications during orthodontic tooth movement. Thirty-seven subjects, 16 males and 21 females (mean age 18.7 years, range 14.0 to 26.7 years), participated in this study. Each subject underwent a session of professional oral hygiene and received oral hygiene instructions; 2 weeks later, a fixed orthodontic appliance was placed on the maxillary arch. A randomly selected maxillary canine was considered as the test tooth, and its antagonist, which had no appliance, was used as the control tooth. From 2 to 12 weeks after orthodontic appliance placement, GCF was harvested from both experimental teeth at the mesiobuccal angle, for GCF volume and LDH activity determinations. Clinical monitoring consisted of recording supragingival plaque presence, bleeding on probing, and probing depth at the same collection sites. The results showed that no differences in clinical conditions and GCF volume occurred between the experimental teeth. On the contrary, GCF LDH activity in the test teeth was significantly greater than that of the control teeth (P <.01). Moreover, no differences were found in the enzymatic activity between the sexes by experimental tooth, and no significant correlation was present between GCF LDH activity and patients' ages within experimental teeth. Our enzymatic results initially indicated a possible role of GCF LDH during the early phases of orthodontic treatment and therefore warrant further study as a possible diagnostic tool for tissue response during orthodontic treatment.