Nickel-titanium Closed-coil Springs Research Articles

Exacerbating orthodontic tooth movement in mice with salt-sensitive hypertension

Background/purposeOrthodontic tooth movement (OTM) is a critical aspect of dental treatment that requires the precise control of bone remodeling processes. Hypertension (HTN) can affect the effectiveness of OTM. Salt-sensitive hypertension (SSHTN) is of particular concern due to its detrimental effects on bone health, potentially altering orthodontic outcomes. This study aimed to investigate the effects of SSHTN on OTM using a mouse model. Materials and methodsMale mice were divided into a normal and an SSHTN group. The SSHTN model was generated by administering N(ω)-nitro-l-arginine methyl ester (l-NAME) followed by a high-salt diet. The OTM was performed using a nickel-titanium (Ni-Ti) closed-coil spring, and the tooth movement was measured after 12 days. Silicone imprinting was used to estimate the OTM distance. Osteoclast activity was assessed using tartrate-resistant acid phosphatase (TRAP) staining of decalcified maxillary sections. ResultsSSHTN mice exhibited significantly increased tooth movement compared to normal mice. This enhanced movement was associated with more osteoclasts in the SSHTN group than in the control group. These findings suggest that SSHTN increases OTM levels by promoting bone resorption. ConclusionSSHTN significantly affected OTM by enhancing osteoclast activity and increasing tooth movement. These results underscore the importance of considering hypertensive conditions in orthodontic treatment planning as they may require adjustments in force application to prevent potential adverse effects.

Role of Pulsed Electromagnetic Field on Alveolar Bone Remodeling during Orthodontic Retention Phase in Rat Models.

Alveolar bone remodeling during the retention phase is essential for successful orthodontic treatment. Pulsed electromagnetic field (PEMF) therapy is an adjunctive therapy for bone-related diseases that induces osteogenesis and prevents bone loss. This study aimed to examine the role of PEMF exposure during the retention phase of orthodontic treatment in alveolar bone remodeling. A total of 36 male Wistar rats were divided into control, PEMF 7, and PEMF 14 groups; a 50 g force nickel-titanium closed-coil spring was inserted to create mesial movement in the first molar for 21 d. Furthermore, the spring was removed, and the interdental space was filled with glass ionomer cement. Concurrently, rats were exposed to a PEMF at 15 Hz with a maximum intensity of 2.0 mT 2 h daily, for 7 and 14 days. Afterwards, the cements were removed and the rats were euthanized on days 1, 3, 7, and 14 to evaluate the expression of Wnt5a mRNA and the levels of RANKL, OPG, ALP, and Runx2 on the tension side. The data were analyzed with ANOVA and post hoc tests, with p < 0.05 declared statistically significant. PEMF exposure significantly upregulated Wnt5a mRNA expression, OPG and ALP levels, and Runx2 expression, and decreased RANKL levels in the PEMF 7 and 14 groups compared to the control group (p < 0.05). This study showed that PEMF exposure promotes alveolar bone remodeling during the orthodontic retention phase on the tension side by increasing alveolar bone formation and inhibiting resorption.

The effect of single versus multiple piezocisions on the rate of canine retraction: a randomized controlled trial

BackgroundPiezocision is a minimally invasive surgical method aiming to accelerate tooth movement. However, its effect was found to be transient, appertaining to the regional acceleratory phenomenon (RAP). Hence, the aim of the study was to evaluate the effect of single and multiple piezocisions on the rate of orthodontic tooth movement (OTM). Moreover, the impact of both protocols on canine tipping and orthodontically induced inflammatory root resorption (OIIRR) has been assessed.MethodsThirty indicated patients for the therapeutic extraction of maxillary first premolars were enlisted in this split-mouth study, and they were randomly split into two equal groups, each including 15 subjects. In the Single Application Group (SAG), one side of the maxillary arch arbitrarily received a single piezocision before the onset of canine retraction, whereas in the Multiple Application Group (MAG), piezocisions were randomly performed on one side, three times on a monthly basis, over the 12-week study period. The contralateral sides of both groups served as the controls. Canine retraction was carried out bilaterally using nickel-titanium closed-coil springs, delivering 150 g of force, and the rate of tooth movement, as well as canine tipping were evaluated on a monthly basis, over a 3-month period. Cone-bean computed tomography scans were also conducted pre- and post- canine retraction, and OIIRR was assessed using Malmgren Index.ResultsThe reported outcomes revealed a significant increase in the amount of canine retraction, canine tipping, as well as root resorption scores on the experimental sides in both groups SAG and MAG post-retraction (p < 0.001). However, upon comparing the experimental sides in both groups, non-significant differences have been observed between them regarding all the assessed outcomes (p > 0.05).ConclusionsSingle and multiple piezocisions effectively accelerate OTM in comparison to conventional orthodontic treatment, with relative outcomes reported by both intervention frequencies. Accordingly, single piezocision is recommended as an adjunct to OTM. Furthermore, significant tooth tipping as well as a significantly higher root resorption risk accompanies both single and multiple piezocision applications in conjunction with OTM.Name of the RegistryClinicaltrials.govTrial Registration NumberNCT05782088Date of Registration23/03/2023 “Retrospectively registered”.URLhttps://clinicaltrials.gov/ct2/show/NCT05782088

Efficacy of low-level laser therapy enhances the rate of canine retraction by increasing &amp;beta; glucoronidase and pentraxin – 3 in gingival crevicular fluid: A clinical study

The aim of the study was to evaluate the efficacy of low-level laser therapy in enhancing the rate of orthodontic tooth movement using β glucoronidase and pentraxin-3 (TNF) biomarkers in gingival crevicular fluid.A split-mouth design was used in 16 subjects (8 experimental and 8 controlled) aged 14 to 25 years, who’s maxillary first premolars were extracted. A gallium-aluminium-arsenide semiconductor diode laser (wavelength, 810 nm; energy density, 10 J/cm2; power output, 100 mW) delivered low-level laser therapy to the experimental canine undergoing distalization at 10 points. The control canine was distalized without low-level laser therapy. The experimental and control canines were distalized using a force of 150 g provided by nickel-titanium closed coil springs. Gingival crevicular fluid was collected at 5 time points from the control and experimental sides, and the levels of β glucoronidase and pentraxin-3 were analysed by enzyme-linked immuno-sorbent assay (ELISA). The rate of canine retraction was calculated by using ortho analyser software.Increased levels of β glucoronidase and pentraxin-3 were observed in the experimental canines compared with the control canines (P &amp;#60;0.001). Cumulative tooth movements over an 8-week experimental period were greater for the experimental canines compared with the control canines. A positive correlation existed between the β glucoronidase and pentraxin-3 levels and the amounts of tooth movement across all time intervals.Low level laser therapy in adjunct with continuous and light forces leads to increase in β glucoronidase and pentraxin-3 leading to accelerated orthodontic tooth movement.: Low-level laser therapy fastens the rate of canine retraction thus accelerating the orthodontic tooth movement. The levels of β glucoronidase and Pentraxin 5 are increased significantly after laser irradiation which aids in accelerating orthodontic tooth movement.

Effect of bone-marrow-derived mesenchymal stem cells on the rate of orthodontic tooth movements in rabbits.

This study aimed to evaluate the effects of BMAC and BM-MSCs on orthodontic tooth movements in rabbits. A100- gram nickel-titanium closed-coil springs were used to initiate orthodontic tooth movement of the lower first premolars in 35 male New Zealand rabbits for 21 days. Using a split-mouth design, autologous BMAC or BM-MSCs were submucosally injected into the right sides of the lower jaw, while the left sides served as the control. On days 7, 14, and 21, a three-dimensional digital model scan was used to measure the amount of tooth movement. The microfocus computed tomography (Micro-CT) and histological findings were examined on day 0 as the baseline measurement and on days 7, 14, and 21. Compared to the control group, the quadrant receiving BMAC and BM-MSCs had a considerably greater amount of tooth movement. Histomorphometric analysis revealed that both BMAC and BM-MSCs had significantly higher numbers of osteoclasts and active bone-resorptive lacunae. The resorptive changes were greater in the BMAC and BM-MSCs groups than in the control group. The submucosal injection of BMAC and BM-MSCs accelerates orthodontic tooth movement (OTM) by decreasing bone density and supplying more osteoclast progenitor cells.

Effectiveness of a low-intensity static magnetic field in accelerating upper canine retraction: a randomized controlled clinical trial

IntroductionNeodymium-iron-boron magnets have been suggested as a contemporary method for accelerating the process of orthodontic tooth movement (OTM).A limited number of clinical trials evaluated their effectiveness in accelerating OTM which is desirable for both orthodontists and patients.The present study aimed to investigate the effectiveness of a low-intensity static magnetic field (SMF) in accelerating upper canine retraction movement.Materials and methodsSeventeen patients (mean age 20.76 ± 2.9 years) with their orthodontic treatment decision to extract the upper and lower first premolars due to bimaxillary protrusion malocclusion were included in this split-mouth study. Canine retraction was performed using Nickel-titanium (Ni-Ti) closed-coil springs (150 g of force on each side). The experimental side received SMF via an auxiliary wire that carried 4-neodymium iron-born magnets with an air gap of 2 mm between the magnets to produce a magnetic field density of 414 mT in the region corresponding to the lateral ligament of the upper canine. To determine the rate of upper canine retraction and upper molar drift, alginate impressions were taken once a month to create plaster casts, which were analyzed digitally via a three-dimensional method.ResultsThe rate of upper canine retraction was significantly greater (P < 0.05) on the SMF side than that on the control side during the first and second months, with an overall duration (19.16%) that was greater than that on the control side. The peak acceleration occurred during the second month (38.09%).No significant differences in upper molar drift were detected between the experimental and control sides (P > 0.05).ConclusionA low-intensity static magnetic field was effective at accelerating upper canine retraction. The difference between the two sides was statistically significant but may not be clinically significant.The SMF did not affect upper molar drift during the upper canine retraction phase.Trial registrationThe trial was retrospectively registered at the ISRCTN registry (ISRCTN59092624) (31/05/2022).

Osteoblast differentiation of Gli1⁺ cells via Wnt and BMP signaling pathways during orthodontic tooth movement

ObjectivesFactors that induce bone formation during orthodontic tooth movement (OTM) remain unclear. Gli1 was recently identified as a stem cell marker in the periodontal ligament (PDL). Therefore, we evaluated the mechanism of differentiation of Cre/LoxP-mediated Gli1/Tomato+ cells into osteoblasts during OTM. MethodsAfter the final administration of tamoxifen to 8-week-old Gli1-CreERT2/ROSA26-loxP-stop-loxP-tdTomato mice for 2 days, nickel–titanium closed coil springs were attached between the upper anterior alveolar bone and the first molar. Immunohistochemical localizations of β-catenin, Smad4, and Runx2 were observed in the PDL on 2, 5, and 10 days after OTM initiation. ResultsIn the untreated tooth, few Gli1/Tomato+ cells were detected in the PDL. Two days after OTM initiation, the number of Gli1/Tomato+ cells increased in the PDL on the tension side. On this side, 49.3 ± 7.0% of β-catenin+ and 48.7 ± 5.7% of Smad4+ cells were found in the PDL, and Runx2 expression was detected in some Gli1/Tomato+ cells apart from the alveolar bone. The number of positive cells in the PDL reached a maximum on day 5. In contrast, on the compression side, β-catenin and Smad4 exhibited less immunoreactivity. On day 10, Gli1/Tomato+ cells were aligned on the alveolar bone on the tension side, with some expressing Runx2. ConclusionsGli1+ cells in the PDL differentiated into osteoblasts during OTM. Wnt and bone morphogenetic proteins signaling pathways may be involved in this differentiation.

En masse retraction of anterior teeth through rapid periodontal distraction by a retraction screw: A randomized control trial

Rapid distraction of the periodontal ligament is an effective method to shorten the orthodontic treatment time. The objectives of the present study were to assess the effects of an HYCON device (Adenta GmbH, Germany) on the rate of en masse retraction of the anterior teeth, duration of retraction, anchorage loss, root resorption, and soft tissue changes. This study was conducted on 60 female patients aged >18 years, divided randomly into two equal groups: Group 1 comprised 30 patients with HYCON, and group 2 comprised 30 patients with nickel-titanium closed coil springs. Skeletal, dental, and soft tissue changes were evaluated on pre- and post-retraction lateral cephalograms, and the rates of anterior tooth movement and anchorage loss were assessed monthly on the dental casts of the patients. Root resorption was assessed using intraoral periapical radiograph. Student's t test was used for the analysis of parametric data, and the Mann-Whitney U test was used for nonparametric data. HYCON significantly shortened the retraction duration by 3 months. The rate of anterior teeth retraction was two times faster in group 1, compared with group 2. There was a significant difference in the anchorage loss between the groups in only first 2 months of treatment. Group 2 showed significantly more root resorption and soft tissue changes than group 1 (P < 0.05). HYCON is an effective device for significantly shortening the duration of retraction with anchorage loss of 2 to 2.5 mm. However, careful monitoring for possible root resorption should be performed.

Displacement and stress distribution pattern during complete mandibular arch distalization using buccal shelf bone screws - A three-dimensional finite element study.

To evaluate and compare the distribution of stress and displacement of teeth during mandibular arch distalization using buccal shelf screws. Three three-dimensional finite element models of mandibular arch were constructed with third molars extracted. Models 1, 2, and 3 were constructed on the basis of the lever arm heights of 0 mm, 3 mm, and 6 mm, respectively, between the lateral incisor and canine. A buccal shelf screw was placed at the area in the second molar region with the initial point of insertion being inter-dental between the first and second molars and 2 mm below the mucogingival junction. MBT pre-adjusted brackets (slot size 0.022 × 0.028") were placed over the clinical crown's center with a 0.019 × 0.025" stainless-steel archwire on three models. A retraction force of 300 g was applied with buccal shelf screws and a lever arm bilaterally using nickel-titanium closed coil springs. The displacement of each tooth was calculated on X, Y, and Z axes, and the von Mises stress distribution was visualized using color-coded scales using ANSYS 12.1 software. The maximum von Mises stress in the cortical and cancellous bones was observed in model 1. The maximum von Mises stress in the buccal shelf screw and the cortical bone decreased as the height of the lever arm increased. Applying orthodontic forces at the level of 6 mm lever arm height resulted in greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of 0 mm lever arm height. Displacement of the entire arch may be dictated by a direct relationship between the center of resistance of the whole arch and the line of action generated between the buccal shelf screw and force application points at the archwire, which makes the total arch movement highly predictable.

Effect of age on orthodontic tooth movement in mice

Background/purposeThe number of middle-aged and elderly orthodontic patients is increasing due to changes in age composition. It is important to investigate the detailed mechanisms of bone remodeling in orthodontic tooth movement (OTM) in the elderly. However, there are few reports on the mechanism of tooth movement in the elderly. The purpose of the present study was to analyze OTM and osteoclastogenesis in aged mice and to elucidate the mechanism. Materials and methodsIt has been reported that tumor necrosis factor (TNF)-α plays an important role in osteoclast formation and OTM. First, 8-week-old and 78-week-old male C57BL/6J mice were subcutaneously injected with TNF-α into the calvaiae, and micro-CT, tartrate-resistant acid phosphatase (TRAP) staining, and real-time PCR were performed to evaluate osteoclast formation and bone resorption. Furthermore, osteoclastogenesis by TNF-α and receptor activator of nuclear factor-kappa B ligand (RANKL) using bone marrow cells was evaluated in vitro. Finally, a nickel-titanium closed-coil spring was attached, mesial movement of the maxillary left first molar was performed, and tooth movement distance and osteoclast formation were evaluated. ResultsCompared to 8-week-old mice, 78-week-old mice had decreased TNF-α-induced bone resorption, osteoclastogenesis, and TRAP and cathepsin K expression in the calvariae. In vitro osteoclast formation also decreased in 78-week-old mice. Furthermore, tooth movement distance and osteoclastogenesis were reduced. ConclusionOTM decreased in aged mice, which was shown to be caused by a decrease in osteoclastogenesis. Therefore, it was suggested that it is necessary to keep in mind that tooth movement may be suppressed when treating elderly patients.

CD40-CD40 ligand interaction between periodontal ligament cells and cementoblasts enhances periodontal tissue remodeling in response to mechanical stress.

We analyzed the localization and expression of Cluster of differentiation 40 ligand (CD40L) in murine periodontal tissue applied with the orthodontic force to determine the CD40L-expressing cells under mechanical stress. Furthermore, we investigated whether CD40-CD40L interaction played an important role in transducing mechanical stress between periodontal ligament (PDL) cells and cementoblasts and remodeling the periodontal tissue for its homeostasis. PDL is a complex tissue that contains heterogeneous cell populations and is constantly exposed to mechanical stress, such as occlusal force. CD40 is expressed on PDL cells and upregulated under mechanical stress. However, whether its ligand, CD40L, is upregulated in periodontal tissue in response to mechanical stress, and which functions the CD40-CD40L interaction induces by converting the force to biological functions between the cement-PDL complex, are not fully understood. The orthodontic treatment was applied to the first molars at the left side of the upper maxillae of mice using a nickel-titanium closed-coil spring. Immunohistochemistry was performed to analyze the localization of CD40L in the periodontal tissue under the orthodontic force. Human cementoblasts (HCEM) and human PDL cells were stretched in vitro and analyzed CD40L and CD40 protein expression using flow cytometry. A GFP-expressing CD40L plasmid vector was transfected into HCEM (CD40L-HCEM). CD40L-HCEM was co-cultured with human PDL cells with higher alkaline phosphatase (ALP) activity (hPDS) or lower ALP (hPDF). After co-culturing, cell viability and proliferation were analyzed by propidium iodide (PI) staining and bromodeoxyuridine (BrdU) assay. Furthermore, the mRNA expression of cytodifferentiation- and extracellular matrix (ECM)-related genes was analyzed by real-time PCR. Immunohistochemistry demonstrated that CD40L was induced on the cells present at the cementum surface in periodontal tissue at the tension side under the orthodontic treatment in mice. The flow cytometry showed that the in vitro-stretching force upregulated CD40L protein expression on HCEM and CD40 protein expression on human PDL cells. Co-culturing CD40L-HCEM with hPDF enhanced cell viability and proliferation but did not alter the gene expression related to cytodifferentiation and ECM. In contrast, co-culturing CD40L-HCEM with hPDS upregulated cytodifferentiation- and ECM-related genes but did not affect cell viability and proliferation. We revealed that in response to a stretching force, CD40L expression was induced on cementoblasts. CD40L on cementoblasts may interact with CD40 on heterogeneous PDL cells at the necessary time and location, inducing cell viability, proliferation, and cytodifferentiation, maintaining periodontal tissue remodeling and homeostasis.

Force Degradation Properties of Two Nickel-Titanium Closed Coil Springs

Force Degradation Properties of Two Nickel-Titanium Closed Coil Springs

Effect of leukocyte platelet-rich fibrin on the rate of canine movement – A prospective and randomized control trial

Objectives: The present study was conducted to investigate the effects of leukocyte and platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction for a period of 5 months. Material and Methods: A split-mouth study was conducted on 16 patients (32 extraction sockets) (Nine males and seven females; age ranging 17–25 years) with Class II Div 1 malocclusion or Class I bimaxillary protrusion, requiring therapeutic extraction of bilateral maxillary first premolars. After the initial leveling and alignment, L-PRF plugs were placed immediately in the randomly selected socket (Experimental Group) and the other side served as control for secondary healing (Control Group). This was followed by the activation of nickel-titanium closed coil springs for canine retraction. The rate of canine movement, canine rotation, tipping, root resorption, and molar movement was assessed at monthly intervals for 5 months (T0–T5). Data were collected from study models. Assessment of pain accompanying the procedure was done using a Likert scale. The trial was registered at the Clinical Trials Registry of India (REF/2022/02/051837). Results: The study revealed that there was a significant increase in the rate of canine movement on the experimental side in the first 2 months and significant molar anchorage loss was seen only in the 1st month. There were statistically non-significant differences in canine rotation, tipping, probing depth, root resorption, and pain perception between the groups. Conclusion: The use of L-PRF plugs in the extraction sockets enhanced the rate of canine movement in the first 2 months of treatment with less anchorage loss and no deleterious effects on periodontium.

Root resorption during maxillary molar intrusion with clear aligners: a randomized controlled trial.

To compare changes in maxillary molar root resorption, intrusion amount, dentoskeletal measures, and maximum bite force (MBF) between clear aligners (CA) and fixed appliances with miniscrew (FM) during molar intrusion. Forty adults with anterior open bite were randomized into either CA or FM groups. Lateral cephalograms, cone-beam computed tomography (CBCT), and MBF were collected at pretreatment (T0) and 6 months of treatment (T1). Maxillary molar intrusion in FM were intruded by nickel-titanium (NiTi) closed-coil spring delivered force (150 grams/side) while clear aligners combined with squeezing exercise were performed in CA. Parametric tests were used for statistical analysis. After 6 months of treatment, significant root resorption of 0.21-0.24 mm in CA and 0.38-0.47 mm in FM were found while maxillary molars were intruded 0.68 and 1.49 mm in CA and FM, respectively. CA showed significant less root resorption and intrusion than FM. Overbite, bite closing, and MBF increased significantly. CA showed significantly less overbite and SN-MP changes but more MBF increase than FM. MBF in CA was correlated with the amount of maxillary molar intrusion (r = 0.736, P < .05). Maxillary molar intrusion and root resorption in CA were half the amount in FM in 6 months. The amount of maxillary molar root resorption was one-third of the intrusion distance. CA displayed less overbite increase and bite closing but more MBF increase than FM. MBF in CA was positively correlated with the molar intrusion amount.

Finite element analysis of tooth movement under different retraction force and intrusive force in double-archwire lingual orthodontics system

The objectives of this study were to evaluate the tooth movement tendency during space closure in maxillary anterior teeth by various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system. Mini-implant-double slot lingual orthodontics system models of the bilateral maxillary first premolar extraction cases were constructed. Three-dimensional finite element models of the maxilla were constructed with definite position mini-implants (8 mm) and power arms (6 mm). Different retraction forces(50gf、100gf、150gf)were applied with the help of a nickel-titanium closed coil spring on the plate side. Intrusive forces(0gf、50gf、100gf)were applied with the help of the mini-implant between the two central incisors, and the initial displacements of the maxillary anterior teeth were analyzed. Variable amounts of displacements like controlled tipping, uncontrolled tipping, lingual crown tipping, labial root tipping, extrusion and distal crown tipping were observed in all the models, and these tendencies increased as the magnitude of retraction force increased, and these tendencies decreased as the magnitude of intrusive force increased. When the intrusive force was greater than or equal to the retraction force, the maxillary central incisors showed the trend of lingual crown tipping and labial root tipping, resulting in uncontrolled tipping movement. In terms of horizontal changes, the increasing width of bilateral anterior teeth was observed, with canines showing the least increasing trend. Various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system provide a new choice for torque control of the anterior teeth. Although anterior mini-implants and elastics can achieve incisor intrusion and lingual root torque, they cannot achieve the expected torque without additional torque control methods.

Evaluation of maxillary canine and molar movement during the first phase of extraction space closure: a multilevel analysis.

This study was designed to analyze and compare the cusp and apex movements of the maxillary canines and first molars during canine retraction in the first step of extraction space closure, and to evaluate if these teeth follow a curvilinear (acceleration and/or deceleration) movement rate. Twenty-five patients (23.3 ± 5.1 years of age) were enrolled. The retraction of the maxillary canines was accomplished using nickel-titanium closed coil springs (100gf) on 0.020-in stainless steel archwire. Oblique cephalograms were traced and superimposed on the anatomic best fit of the maxilla (before the retraction [T0], and after one month [T1], three [T3], five [T5] and seven [T7] months). Statistics was based in a normally distributed data. Multilevel procedures were used to derive polynomials for each of the measurements. Student's t-test and one-way repeated measures ANOVA were conducted. The level of significance of 5% was adopted. Canine cusps and apexes did not follow a quadratic curve regarding horizontal movement (neither accelerate nor decelerate). Canine and molar cusps showed more horizontal movement than apexes (4.80 mm vs. 2.78 mm, and 2.64 mm vs. 2.17 mm, respectively). Canine did not accelerate or decelerate overtime horizontally; the cusps and apexes of the canines and molars showed more horizontal movement and larger rate at the beginning of canine retraction, followed by significantly smaller and constant movement rate after the first month.

Differentiation ability of Gli1+ cells during orthodontic tooth movement.

Orthodontic tooth movement (OTM) induces bone formation on the alveolar bone of the tension side; however, the mechanism of osteoblast differentiation is not fully understood. Gli1 is an essential transcription factor for hedgehog signaling and functions in undifferentiated cells during embryogenesis. In this study, we examined the differentiation of Gli1+ cells in the periodontal ligament (PDL) during OTM using a lineage-tracing analysis. After the final administration of tamoxifen for 2days to 8-week-old Gli1-CreERT2/ROSA26-loxP-stop-loxP-tdTomato (iGli1/Tomato) mice, Gli1/Tomato+ cells were rarely observed near endomucin+ blood vessels in the PDL. Osteoblasts lining the alveolar bone did not exhibit Gli1/Tomato fluorescence. To move the first molar of iGli1/Tomato mice medially, nickel-titanium closed-coil springs were attached between the upper anterior alveolar bone and the first molar. Two days after OTM initiation, the number of Gli1/Tomato+ cells increased along with numerous PCNA+ cells in the PDL of the tension side. As some Gli1/Tomato+ cells exhibited positive expression of osterix, an osteoblast differentiation marker, Gli1+ cells probably differentiated into osteoblast progenitor cells. On day 10, the newly formed bone labeled by calcein administration during OTM was detected on the surface of the original alveolar bone of the tension side. Gli1/Tomato+ cells expressing osterix localized to the surface of the newly formed bone. In contrast, in the PDL of the compression side, Gli1/Tomato+ cells proliferated before day 10 and expressed type I collagen, suggesting that the Gli1+ cells also differentiated into fibroblasts. Collectively, these results demonstrate that Gli1+ cells in the PDL can differentiate into osteoblasts at the tension side and may function in bone remodeling as well as fibril formation in the PDL during OTM.

Does leukocyte-platelet-rich fibrin (L-PRF) cause long term acceleration in the rate of canine retraction? A split-mouth, two-arm parallel group, randomized control trial

ABSTRACT Objective: The present study was conducted to investigate the effects of leukocyte-platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction for a period of 5 months. Methods: A split-mouth study was conducted on 16 subjects (9 males and 7 females; age range 17-25 years; mean age, 21.85±2.45 years) who required therapeutic extraction of bilateral maxillary first premolars. After the initial leveling and alignment, L-PRF plugs were placed in a randomly selected extraction socket (Experimental Group), and the other side served as a control (Control Group). Canine retraction was carried out by the activation of nickel-titanium (NiTi) closed-coil springs delivering 150 g of force. The rates of canine movement, canine rotation, tipping, root resorption, and molar movement were assessed at monthly intervals for five months (T0-T5). Pain, swelling and discomfort accompanying the procedure were assessed using a Likert scale. Results: The study revealed a significant increase in the rate of canine movement on the experimental side in the first two months, and significant molar anchorage loss was observed only in the first month for control side. There were no statistically significant differences between the groups regarding canine rotation, tipping, probing depth, root resorption, and pain perception. Conclusions: The use of L-PRF plugs in extraction sockets considerably enhanced the rate of canine movement only in the first two months, and long-term efficacy was not observed in this study.

Rate of upper incisor retraction in Class II division 1 patients managed with palatal versus buccal miniscrew supported segmental orthodontics: Randomized parallel clinical trial

This study was conducted to compare maxillary incisor retraction rates using buccal orthodontics with segmented arch approach supported by a buccal or palatal mini-screw in non-growing Class II Division 1 patients during a 3-month period. All patients between September 2018 and December 2021 with following criteria were included: non-growing class II division 1 protrusion, indication for premolar extraction, no or little crowding, normal overbite, no previous orthodontic treatment, no systematic disease, good oral hygiene, no periodontal problems or oral habits. Mini-implant was inserted buccally or palatally between upper second premolar and first molar bilaterally. Incisor retraction was manipulated by a 200-gram force through a nickel-titanium closed-coil spring extended from the mini-implant to the segmental design. Study casts were made before retraction and after every 4 weeks (T0: baseline, T1: 4 weeks, T2, 8 weeks, T3: 12 weeks). A repeated measures ANOVA was performed for total comparison of data (mm of retraction) on 3D casts. A pairwise t test with Bonferroni correction was used for comparison between two experimental periods for the same group. An independent samples t-test was also used for comparison between two groups for the same experimental period. Of 30 patients meeting the eligibility criteria, only 28 were included with mean age 16±2.5 years. Repeated measures ANOVA revealed significant differences in incisor retraction between the time intervals for both buccal and palatal groups (P=0.001). In addition, the paired-sample t test indicated a significant difference between each time interval for both the buccal and palatal groups (P=0.001), except between T3 and T2 for the palatal group (P=0.09). The independent sample t-test revealed significant differences between the buccal and palatal groups at T1 (Mean: 0.55 [0.355-0.748],=0.001) and T2 (Mean: 1.4 [0.91-1.88], P=0.001); whereas no significant difference was found at T3 (Mean: 1.15 [0.67-1.63], P=0.945). Anterior retraction using a segmental palatal model with mini-screws was effective regardless of the buccal or palatal situation of the minivis. Retraction of incisors with palatal miniscrews was significantly faster in the first two months.

Anti-inflammatory effect of caffeic acid phenethyl ester supplementation on TNF-α and NF-κB expressions throughout experimental tooth movement in vivo

Context: Orthodontic tooth movement (OTM) changes the periodontal tissue and increases the incidence of root resorption (OIRR). Caffeic acid phenethyl ester (CAPE), an antioxidant and anti-inflammatory chemical generated from honey propolis, might be useful in controlling inflammation during OTM and so reducing the risk of OIRR. Aims: To evaluate if CAPE supplementation has an anti-inflammatory impact on tumor necrosis factor-α (TNF-α) and nuclear transcription factor κB (NF-κB) during experimental OTM in male Wistar rats (Rattus novergicus). Methods: Forty-eight healthy male Wistar rats were divided into positive control group (OTM 10 g/mm2 force application) and experimental group (OTM application and CAPE administration). Each groups were observed for 3, 7, 14 days. A nickel-titanium closed coil spring that was 8.0 mm long, thick was inserted between the upper left first molar and upper central incisor in order to move the molar mesially. A 20 mg/kg body weight dose of CAPE was taken orally. Using immunohistochemistry, the expression of TNF-α and NF-κB was examined on the compression side of the OTM. Both the Tukey's honest significant difference test and the one-way analysis of variance test were applied (p&lt;0.05). Results: TNF-α and NF-κB expression in the compression side differed considerably across groups (p&lt;0.05). Daily administration of CAPE significantly downregulates TNF-α and NF-κB expression on the compression side. Conclusions: Administration of CAPE throughout OTM can successfully reduce the number of TNF-α and NF-κB expressions in the compression side in vivo.