Bracket Slot Research Articles

Various methods of ligation ties

During fixed orthodontic treatment, ligation is used to keep the arch wire in the slot of the bracket. It can also be used to move the tooth in a particular direction depending upon the type of ligature used and its method of ligation. Ligation can be done using Stainless steel (SS) ligatures or elastomeric modules. SS ligature wire provides secured tie of arch wire to bracket slot, lesser friction and slower rate of force decay compared to elastomeric modules. Elastomeric modules are easier to place and take lesser chair side time. Elastic ligature does not have sharp edges and they exert lesser force on the bracket. So, they are preferred in those situations where there is higher tendency for debonding of brackets. Elastic ligature may be a substitute for the wire ligatures in most situations. In various treatment mechanics ligation ties are modified to accomplish variable tooth movement or to maintain arch form integrity during finishing of an orthodontic case. This article will highlight different ligation ties used in different bracket systems and their indications as well. Keywords: Ligation Ties, Stainless steel Ligation, Elastic modules, Rotation ties.

Does anchorage loss differ with 0.018-inch and 0.022-inch slot bracket systems?

To compare maxillary first molar anchorage loss between 0.018-inch and 0.022-inch slot fixed appliance systems. Patients requiring bilateral maxillary premolar extractions (n = 74) within a randomized clinical trial comparing the effectiveness of 0.018-inch and 0.022-inch slot MBT bracket systems (3M-Unitek, Monrovia, Calif) were included. Three-dimensional pre- and posttreatment digital models were landmarked and measured (R700 scanner and OrthoAnalyzer software, 3Shape, Copenhagen, Denmark). Anteroposterior position of the first molars was measured using the third medial rugae point as a reference. Anchorage loss (AL) represented the subtraction of the posttreatment distance from the pretreatment distance for both anchorage loss right (ALR) and left (ALL) sides. The values were then compared using a two-way analysis of variance. There were 41 and 33 cases for the 0.018-inch and 0.022-inch bracket slot systems, respectively. The baseline characteristics were similar between groups, except for the presence or absence of anchorage devices (P = .050). For the total sample: 0.018-inch ALR = 3.86 mm, ALL = 3.30 mm and 0.022-inch ALR = 3.73 mm, ALL = 3.47 mm (P = .970). There was also no significant difference between the 0.018-inch and 0.022-inch groups when subjects with anchorage devices were excluded (P = .383). Bracket slot size does not influence maxillary molar anchorage loss during orthodontic treatment.

In vitro comparison of frictional forces of a new polycrystalline ceramic bracket versus metal-insert ceramic bracket before and after aging

The purpose of this study was to compare the friction of two types of polycrystalline ceramic brackets before and after aging. A total of 60 second-upper right premolar brackets were divided into two groups: Clarity™ Advanced (3M Unitek, Monrovia, CA) and Clarity™ (3M Unitek). All brackets had a nominal 0.022-in slot size and a McLaughlin Bennett Travesi (MBT) prescription. Each bracket was submitted to a friction test, using the YL01 UTM universal testing machine (YLE GMBH, Germany) before and after thermocycling. All tests were carried out in the presence of artificial saliva, using .019×.025-in. rectangular stainless steel (SS) archwires (3M Unitek). Bracket slot surfaces were observed under an optical microscope (Olympus CX41, Tokyo, Japan) before and after aging. Before aging, the Clarity Advanced group showed significantly lower friction than the Clarity group (P=0.011). After aging, the friction of the Clarity Advanced bracket decreased significantly (P<0.001), whereas the friction of the Clarity bracket increased significantly (P<0.001). The microscopic qualitative evaluation showed that the slot surfaces of all aged Clarity brackets revealed important pit corrosion when compared with the original brackets. The new Clarity Advanced ceramic bracket shows good physical friction properties due to the various modifications added by the manufacturers.

In vivo and in vitro evaluation of the mechanical properties of orthodontic elastomeric ligatures

BackgroundElastomeric ligatures are polyurethane materials for securing arch wires into bracket slots. The mechanical properties of these ligatures deteriorate over time when exposed to different media prolonging treatment time. ObjectivesTo determine the mechanical properties of different brands of elastomeric ligatures in three media. MethodologyExperimental study assessing four brands of elastomeric ligatures: Dalton, American Orthodontics, Ormco, and Orthoclassics. A total of 120 ligatures per brand were divided equally and exposed to the oral environment, dry medium, and artificial saliva for 6 weeks. A digital force gauge was used to measure maximum tensile force and maximum tensile extension before and after exposure of elastomeric ligatures to the media. Normal distribution was assessed using Kolmogrov-Smirnoff test. Analysis of variance was used to compare mean maximum tensile force and mean maximum tensile extension between and within groups of elastomeric ligatures; level of significance was set at P < 0.05. ResultsTensile properties of all brands of elastomeric ligatures were significantly different from one another in as-received condition. After 6 weeks in the different media, all the ligatures experienced a significant reduction in maximum tensile force P < 0.0001, whereas Ormco and American Orthodontics were the only brands with significant difference in maximum tensile extension in all the media P < 0.0001. ConclusionThere were significant differences in mechanical properties of the elastomeric ligatures of the brands in as-received condition and after exposure to different media.

Precision of the dimensions of orthodontic bracket slots – systematic review

Abstract Introduction: The aim of this study was to revising and presenting results of in vitro studies referring to the precision of the dimensions of orthodontic brackets’ slots. Materials and methods: Search was proceeded for studies describing results of measurements of the dimensions of orthodontic brackets slots performed with the use of various available measuring instruments. Brackets from various manufacturers were taken into consideration. Search was performed in Pub-Med and Google Scholar. The following keywords were used: „bracket slot”, „orthodontic bracket slot dimension”. Studies were included, if they based on two separate measurements: at the slot opening and along the slot bottom. Studies were rejected if they described an analysis of bracket slot structure or roughness without providing slot dimensions. Results: Finally, 13 papers were selected from PubMed and 9 papers – from Google Scholar (all the papers from PubMed were found in Google Scholar as well). All the studies analysed, regardless of the method of measurement and material used for the manufacturing of orthodontic brackets revealed, that slot dimensions were higher or lower than the declared standard size. Moreover, analysis of slot appearance provided interesting information pertaining to the shape of bracket slots, e.g. parallelism, convergence or divergence of their walls. Conclusions: Basing on the review it can be stated that orthodontic brackets are characterized by imperfections that may characterize single brackets, bracket sets or series. They may potentially influence the process of three-dimensional aligning of individual teeth during orthodontic treatment.

Force‐deflection behaviour of NiTi archwires in a polytetrafluoroethylene (Teflon) bracket system

AbstractIn orthodontic treatment, archwire forces for tooth movement is influenced by the magnitude of friction encountered during the sliding motion of archwire along the bracket slot. Friction will reduce the archwire force, and subsequently modify the constant force delivery trend into a slope. The aim of this work is to investigate the force‐deflection behaviour of nickel‐titanium (NiTi) shape memory alloy archwire on polytetrafluoroethylene (Teflon) as the bracket. Sliding tests was performed to determine the coefficient of friction of polytetrafluoroethylene‐NiTi material combinations. The force‐deflection behaviour was evaluated from a modified bending tests, at two different configurations; commercial stainless‐steel bracket and hand‐made polytetrafluoroethylene bracket. During test, wires were deflected into different deflections (2 mm, 3 mm and 4 mm) by using four commercial NiTi archwires at different sizes and geometry. From the test; coefficient of friction for polytetrafluoroethylene‐NiTi wire was recorded as small as 0.07. On force‐deflection graphs, bending load on 3 mm and 4 mm deflection were observed higher on stainless steel (SS) bracket compared with polytetrafluoroethylene bracket. Due to small coefficient of friction on polytetrafluoroethylene‐NiTi configuration, the NiTi archwire exhibited the activation and deactivation force within the plateau limit. Greater friction on stainless steel‐nickel‐titanium bracket configuration causes wire to release force in a slope trend. This finding highlights the potential of polytetrafluoroethylene as a material in the bracket slot to minimize friction during orthodontic treatment.

Biomechanical analysis for total distalization of the mandibular dentition: A finite element study.

The aim of this finite element study was to analyze and clarify the mechanics of tooth movement patterns for total distalization of the mandibular dentition based on force angulation. Long-term orthodontic movement of the mandibular dentition was simulated by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. Displacement of each tooth was caused by movement of the whole dentition, elastic deflection of the archwire, and clearance gap between the archwire and bracket slot. The whole dentition was rotated clockwise or counterclockwise when the line of action of the force passed below or above the center of resistance. Elastic deflection of the archwire induced a lingual tipping of the anterior teeth. It became larger when increasing the magnitude of angulation. The archwire could be rotated within the clearance gap between the archwire and the bracket slot, and thereby the teeth tipped. Mechanics of total mandibular distalization was clarified. Selective use of force angulation with a careful biomechanical understanding can achieve proper distalization of the whole mandibular dentition.

Evaluation of surface roughness of the bracket slot before and after burning

Slot bracket base is one important element to enable sliding movement of the archwire. Bracket reconditioning by means of burning changes the surface roughness of slot bracket base. The heat above 450 °C shows microstructure changes of the slot surface. On this basis, the present study aims to evaluate surface roughness changes of the slot bracket base before and after reconditioning by means of burning. Sixteen premolar brackets standard edgewise were divided into two groups each consisting of eight brackets. These two groups were tested at three different points using Scanning Electron Microscopy (SEM), with 3000 times of magnification. Subsequentl,group A was burned for 5 seconds (approximately 450 °C) and group B was burned for 10 seconds(approximately 643 °C). After treatment,these two groups were tested for the second time using Scanning Electron Microscopy (SEM), with 3000 times magnification and the images were analyzed using a discrete scale quantitative classification. Afterwards, the data were analyzed using ANOVA (p≤0.05) and post hoc analysis. The result showed that surface roughness of the slot bracket base burned for 10 seconds experienced more significant change than that of bracket burned for 5 seconds and that of the control bracket(p≤0.05).Bracket reconditioning using burning either for 5 to 10 seconds change the surface roughness of the slot bracket base.

Fracture strength of monocrystalline and polycrystalline ceramic brackets during archwire torque

Abstract Introduction In recent years, there has been an increasing demand for esthetic treatments, especially among orthodontic patients. Objective This study determined the fracture strength of monocrystalline and polycrystalline ceramic brackets of different manufacturers during archwire torque. Material and method Sixty ceramic brackets (Roth, right upper central incisors, 0.022 x 0.028-inch slot) were allocated into two groups (30 specimens per group) according to the type of ceramics: monocrystalline and polycrystalline. Subsequently, the groups were divided into three subgroups (n = 10) according to the manufacturer: Orthometric, Eurodonto and Ortho Technology. Sixty PVC cylinders were filled with chemically activated acrylic resin (CAAR), the brackets were fixed with CAAR onto the cylinder surface and the excess material was used to partially cover the base of the bracket. After 24h, the U-shaped wire base (0.019 x 0.025 inches; 6 mm height and width) was inserted into the bracket slot and fixed thereon with a stainless-steel wire. Vertical folds were made at the ends of the “U” to support the universal test machine chisel. The fracture strength test was performed at a speed of 1.0 mm/min until fracture into a universal test machine (Instron). The data were recorded, transformed into g.mm and submitted to two-way ANOVA followed by Tukey’s post-hoc test (SAS Institute Inc., Cary, NC, USA, version 9.3) (α=5%). Result Monocrystalline brackets showed a higher fracture strength than polycrystalline brackets, regardless of the manufacturer (p&lt;0.05). The highest fracture strength values were observed in Ortho Technology and Orthometric brackets, with no significant difference between them (p&gt;0.05). Conclusion Monocrystalline ceramic brackets have a higher fracture strength than polycrystalline brackets, with significant manufacturer-dependent differences.

Lubricating conditions: effects on friction between orthodontic brackets and archwires with different cross-sections.

Objective: This study investigated the effect of the condition of lubrication on the friction between brackets and NiTi archwires of different rounded cross-sections. Methods: Brackets (Roth, GAC) were affixed to a device connected to a universal testing machine into which segments of archwire were placed (NiTi, Nitinol, GAC) with cross-sections of 0.012-in, 0.016-in and 0.020-in. Once the wire was in the bracket slot, the following lubricants were applied: human saliva (HS: positive control), distilled water (DI), mucin-based (MUC) or carboxymethylcellulose-based (CMC) artificial saliva. In the negative control group, no lubricant was used. The combination between the wire cross-sections and the lubrication condition generated 15 groups with 15 samples each. Data were submitted to two-way analysis of variance and Tukey’s test. Results: There was no significant interaction between the wire cross-section and the condition of lubrication (p= 0.901). Irrespective of whether lubricants were used or not, there was a significant increase in friction with an increase in the cross-section of the wire (p< 0.001). For any wire, the group tested in the presence of MUC was not different from that in which HS was applied. On the other hand, when the application of lubricants was suppressed, significantly higher friction values were observed. The CMC group and the DI group demonstrated intermediate behavior. Conclusions: Friction increased with the increase of the cross-section of the NiTi archwire, but regardless of the archwire, friction with MUC artificial saliva was similar to that of HS and lower than in dry conditions.

Are self-ligating brackets’ slots dimensions accurate?

The purpose of this study is to measure the dimensions of the slot's top and base of passive self-ligating brackets of three commercial and available systems and to compare the measured dimensions with the manufacturers' published dimensions. Digital microscope was used to measure the slot's top and base of 40 Central incisor brackets by three different manufacturers, Carriere SLX (Ortho Organizer, USA), Damon Q (Oramco USA) and Smart Clip (3M Unitek USA). The measurements were taken after the doors of all brackets were removed and compared with the manufacturers' claimed dimensions. All brackets showed a significant increase in dimensions from both the slot's top and base compared to the manufacturers' published dimensions. For the base of the bracket's slot, Carriere SLX brackets showed the least difference while Damon Q brackets had the greatest. Moreover, for the top of the bracket's slot, the Smart clip brackets showed the greatest difference. The percentage of difference between the actual measurements and the manufacturers' prescriptions shows that for the slot's base, Carriere SLX brackets had the smallest percentage increase by .36%, followed by Smart clip by 6.7% and the Damon Q brackets by 8.1%. While for the slot's top Carriere SLX had the smallest percentage increase by .72%, followed by Damon Q by 12.3% increase and finally Smart Clip brackets by 12.8%. The actual measurements of passive self-ligating brackets from 3 manufacturers were larger than the manufacturers' published dimension. This amount of increase may affect the amount torque expression.

Bracket slot size selection: after all a matter of taste?

The publication of the three-paper series on the effects of two slot sizes on treatment parameters in this issue, targets a topic, which has attracted a lot of discussion based primarily on anecdotal evidence. The conclusive evidence contribute to the lack of variation of treatment variables with slot size selection, clarifies one of the traditional beliefs on this issue; several others still hold strong however. This commentary has the objective of highlighting some points, which could be taken into consideration in interpreting the results of this three-part trial.

Novel methods reveal that parallelism contributes to the functional vertical slot dimension in ceramic and metal brackets

To validate a novel method for measuring the clinically relevant bracket slot and use these methods to test the hypothesis that various metal injection molded (MIM) and esthetic ceramic injection molded (CIM) brackets have a bracket slot accuracy within 1 mil (0.001") of their reported slot dimension. A Nikon iNEXIV-VMA-2520 laser microscope was used to measure slots of six series of CIM brackets and two series of MIM brackets via a vision measuring system of 256 gray levels to capture each edge of the slot, largely taking out human subjectivity. This system had a maximum permissible error of 2 + 8 L/1000 μm with a point resolution of 0.1 μm and was estimated to be more accurate than previous methods by a factor of 10. The video image for each bracket was autofocused by a blinded operator, and 40 point-to-line measurements were calculated along the clinical slot and averaged. Vertical slot dimension varied from series to series and within the series of brackets. Three of six CIM and two of three MIM brackets had a statistically significant mean slot size 0.001 inches larger than reported. The reported precision of these CIM brackets, as determined from standard deviation, varied from series to series. A novel system that incorporates parallelism into analysis of vertical bracket slot dimension was described. When the entire clinically relevant slot was considered, MIM and CIM brackets had similar precision but were significantly oversized, with contribution from a nonparallel, likely diverging, vertical slot dimension.

Finite element analysis of orthodontic bracket tie wing deformation due to labial crown torque

To measure the tie wing deformation of conventional orthodontic bracket during applied archwire torque using finite element analysis (FEA). Maxillary (upper) right central incisor stainless steel (SS) conventional orthodontic bracket dimensions were obtained using profile projector. A three-dimension model of the bracket was done. A finite element (FE) model of the bracket was constructed. A SS archwire applied torque was obtained theoretically for the angles of twist from 5° to 40°. Rectangular archwire labial crown torque was applied as a couple in two positions into the bracket slot. Further, the SS bracket profile was considered as ceramic to study the effect of materials. The FE results showed that there was increased bracket tie wing deformation with increasing torque in both the materials. The tie wing deformation varies from 0.24 μm to 12.4 μm and 0.153 μm to 6.65 μm for SS and ceramic respectively. The deformation of occlusal side tie wings was more than the gingival side tie wings. Tie wing deformation leads to the loss of applied torque and might delay the tooth movement. This insilico study visualizes the orthodontic bracket tie wing deformation to clinicians.

Effect of patterns of stainless steel ligation on orthodontic bracket with contact boundary conditions using finite element analysis

The objective of this work was to analyse the stress and deformation in the orthodontic bracket and archwire with different patterns of ligature tying namely full round pattern I (P-I), the figure of eight pattern II (P-II) and figure of eight pattern III (P-III) using finite element analysis (FEA). A standard edgewise stainless steel (SS) maxillary right central incisor orthodontic bracket was measured using profile projector. Solid models of the bracket, archwire and three patterns of ligature tie were done. The archwire was modelled and assembled into the bracket slot. The FE model of the assembly was done. Effect of three patterns of ligation on the archwire and bracket was analysed by applying archwire torque as a couple. The stress in the bracket and archwire for the patterns of ligation P-I, P-II and P-III were noted. The maximum deformation of the bracket and archwire for the patterns of ligation P-I, P-II and P-III were obtained. From the analysis, it was concluded that the magnitude of stress in the archwire and the deformation value in the bracket was high in P-I pattern. Ligature pattern P-II developed the least amount of stress and deflection in the bracket and archwire.

WILLIAMS SENDROMLU HASTANIN ORTODONTİK TEDAVİSİNİN SONUÇLARI VE TEDAVİDEKİ ZORLUKLAR

Williams Syndrome (WS) is a rare congenital and progressive multisystem disorder which is described with specific systemic disorders, skeletal and dental abnormalities and tongue thrusting. A 13-year-old patient applied to our clinic with complaining dental caries, malocclusion and tongue thrusting. The patient was treated with a full fixed standard edgewise appliance named as Mini Master Series from American Orthodontics (Central Islip, N.Y., USA), 0.018 inch bracket slots) for 2 years and 8 months. Despite poor oral hygiene, frequent appointments helped to complete the orthodontic treatment of the patient without caries formation. Also extraction of first molars with uncertain prognosis provided social benefits when it was compared to healthy premolar extractions. This case report presents the successful results of the orthodontic therapy and difficulties of an orthodontic treatment of a patient who was diagnosed with WS.

Radiographic Comparison of Apical Root Resorption During Orthodontic Treatment with Bracket Slot Size 0,018 inch and 0,022 inch

Objectives: Orthodontic induced apical root resorption is an unavoidable side effect of orthodontic treatments which is seen in more than 90% of the cases. Orthodontic Induced Inflammatory Root Resorption (OIIRR) occurs as a result of individual biologic variations and mechanical stimuli effects. Material and method: In this study the extent of root resorption is compared in patients who have received fixed orthodontic treatment (by straight wire system), with two different sizes of slots (0.018 inch and 0.022 inch) and the same wire diameter. For this purpose, panoramic radiographs were used to examine some 720 teeth before and after the treatment. Two different approaches were used to evaluate the root resorption, first based on Malgren classification and the other based on Crown-Root ratio (C/R). Result: Average duration of treatment for patients treated by 0.018-inch slot brackets was 26 months and for those who were treated by 0.022-inch slot brackets it was 25 months. No significant difference was found in the two groups explored in this study (p-value = 0.684). Slot size has no effect on root resorption and there are some other features including the efficiency of the slots which might be influential. Conclusion: As no significant difference was found in the two groups explored in this study, it could be argued that slot size has no effect on root resorption and there are some other features including the efficiency level of the slots which might be influential. As previous studies indicate, 0.022-inch slot brackets could have more influence on root resorption. Apex shape has no effect in that regard.

Finite element analysis of slot wall deformation in stainless steel and titanium orthodontic brackets during simulated palatal root torque.

Torque applied on anterior teeth is vital for root positioning and stability. The aim of this study was to evaluate the detailed slot wall deformation in stainless steel (SS) and titanium (Ti) edgewise brackets during palatal root torque using finite element analysis. A finite element model was developed from a maxillary central incisor SS bracket (0.022 in). The generated torque values from an SS rectangular archwire (0.019×0.025 in) while twisting from 5° to 40° were obtained experimentally by a spine tester, and the calculated torque force was applied in the bracket slot. The deformations of the slot walls in both SS and Ti brackets were measured at various locations. There were gradual increases in the deformations of both bracket slot walls from the bottom to top locations. In the SS bracket slot for the 40° twist, the deformations were 9.28, 36.8, and 44.8μm in the bottom, middle, and top slot wall locations, respectively. Similarly, in the Ti bracket slot for the 40° twist, the deformations were 39.2, 62.4, and 76.2μm in the bottom, middle, and top slot wall locations, respectively. The elastic limits were reached at 28° for SS and at 37° for Ti. Both SS and Ti bracket slots underwent deformation during torque application. There are variations in the deformations at different locations in the slot walls and between the materials.

Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study.

The aim of this study was to evaluate the efficacy of tooth alignment with conventional and self-ligating labial and lingual orthodontic bracket systems. We tested labial brackets (0.022″ slot size) and lingual brackets (0.018″ slot size). The labial brackets were: (i) regular twin brackets (GAC-Twin [Dentsply]), (ii) passive self-ligating brackets including (Damon-Q® [ORMCO]; Ortho classic H4™ [Orthoclassic]; FLI®SL [RMO]), and (iii) active self-ligating brackets (GAC In-Ovation®C [DENTSPLY] and SPEED™[Strite]). The lingual brackets included (i) twin bracket systems (Incognito [3M] and Joy™ [Adenta]), (ii) passive self-ligating bracket system (GAC In-Ovation®LM™ [Dentsply]), and (iii) active self-ligating bracket system (Evolution SLT [Adenta]). The tested wires were Thermalloy-NiTi 0.013″ and 0.014″ (RMO). The archwires were tied to the regular twin brackets with stainless steel ligatures 0.010″ (RMO). The malocclusion simulated a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). The results showed that lingual brackets are less efficient in aligning teeth when compared with labial brackets in general. The vertical correction achieved by labial bracket systems ranged from 72 to 95 per cent with 13″ Thermalloy wires and from 70 to 87 per cent with 14″ Thermalloy wires. In contrast, the achieved corrections by lingual brackets with 13″ Thermalloy wires ranged between 25-44 per cent and 29-52 per cent for the 14" Thermalloy wires. The anteroposterior correction achieved by labial brackets ranged between 83 and 138 per cent for the 13″ Thermalloy and between 82 and 129 per cent for the 14″ Thermalloy wires. On the other hand, lingual brackets corrections ranged between 12 and 40 per cent for the 13″ Thermalloy wires and between 30 and 45 per cent for the 14″ Thermalloy wires. This is a lab-based study with different labial and lingual bracket slot sizes (however they are the commonly used ones in clinical orthodontics) and study did not consider saliva, periodontal ligament, mastication and other oral functions. The effectiveness of lingual brackets in correcting vertical and anteroposterior displacement achieved during the initial alignment phase of orthodontic treatment is lower than that of the effectiveness of labial brackets.

Stress distribution of maxillary first molar PDL with highpull headgear traction; A finite element analysis

Statement of the problemHeadgear is most commonly used to correct anteroposterior discrepancies. Headgear can also be used to make more space for teeth to come in. In this instance the headgear is attached to the molars, via molar headgear bands and tubes, and helps to draw these molars backwards in the mouth, opening up space for the front teeth to be moved back using braces and bands. Stress on PDL of molars teeth and soreness of teeth when chewing, or when the teeth touch, is typical. Adults usually feel the soreness 12–24 h later, but younger patients tend to react sooner. PurposeApplication of heavy forces to maxillary dentition during treatment with headgear, induces high concentration of stresses in periodontal tissue. Quantification of this stress is of great concern in orthodontics. This study was designed to investigate the quantity and quality of stress response in the PDL of maxillary first molar which was subjected to highpull headgear traction using Finite Element Method. Materials and methodIn an experimental study, a three-dimensional finite element model of maxillary dentition, consisting of 17096 elements & 23013 nodes, was developed based on a young human skull. The forces were applied to the maxillary first molar in the stabilized arch by means of a rectangular full size arch wire in (022) slot bracket. Mechanical properties of this model were based on previous studies. A 350 g force was used for high pull headgear to affect the dentition (+30°) and stress distribution was investigated in buccal, palatal, mesial and distal side and in cervical, middle, apical sections of the PDL. The quantity of stresses were expressed as principal stresses, while the negative and positive signs indicated compressive and tensile stresses respectively. ResultsThe buccal surface of PDL of mesiobuccal root and the buccal, palatal, and distal surface in cervical regions of PDL of distobuccal root and the distal surface of the PDL of palatal root had received a great deal of stresses, in addition, the over all stress distribution in roots of molar had intrusive nature. ConclusionThe distribution of high stress concentration areas observed after using high pull headgear is limited to some root surfaces specially the distobuccal root.