Bodily Tooth Movement Research Articles

Effect of material composition and thickness of orthodontic aligners on the transmission and distribution of forces: an in vitro study.

To investigate the effects of material type and thickness on force generation and distribution by aligners. Sixty aligners were divided into six groups (n = 10): one group with a thickness of 0.89mm using Zendura Viva (Multi-layer), four groups with a thickness of 0.75mm using Zendura FLX (Multi-layer), CA Pro (Multi-layer), Zendura (Single-layer), and Duran (Single-layer) sheets, and one group with a thickness of 0.50mm using Duran sheets. Force measurements were conducted using Fuji® pressure-sensitive films. The lowest force values, both active and passive, were recorded for the multi-layered sheets: CA Pro (83.1N, 50.5N), Zendura FLX (88.9N, 60.7N), and Zendura Viva (92.5N, 68.5N). Conversely, the highest values were recorded for the single-layered sheets: Duran (131.9N, 71.8N) and Zendura (149.7N, 89.8N). The highest force was recorded at the middle third of the aligner, followed by the incisal third, and then the cervical third. The net force between the incisal and cervical thirds (FI-FC) showed insignificant difference across different materials. However, when comparing the incisal and middle thirds, the net force (FI-FM) was higher with single-layered materials. Both overall force and net force (FI-FM) were significantly higher with 0.75mm compared to those with a thickness of 0.50mm. Multi-layered aligner materials exert lower forces compared to their single-layered counterparts. Additionally, increased thickness in aligners results in enhanced retention and greater force generation. For effective bodily tooth movement, thicker and single-layered rigid materials are preferred. This research provides valuable insights into the biomechanics of orthodontic aligners, which could have significant clinical implications for orthodontists. Orthodontists might use this information to more effectively tailor aligner treatments, considering the specific tooth movement required for each individual patient. In light of these findings, an exchangeable protocol for aligner treatment is suggested, which however needs to be proven clinically. This protocol proposes alternating between multi-layered and single-layered materials within the same treatment phase. This strategy is suggested to optimize treatment outcomes, particularly when planning for a bodily tooth movement.

In vitro biomechanics of divot use, and their placement, in orthodontic aligner therapy.

To evaluate biomechanics of an aligner utilizing divots and the effect of their vertical placement on the right maxillary central incisor. An invitro Orthodontic SIMulator (OSIM) was used to test forces and moments generated by aligners incorporating divots. The OSIM arch was scanned to generate a. STL version that was modified to create four models by placing divots on different positions of the right central maxillary incisor: GI - divots on gingival-third of lingual surface and incisal-third of labial surface; GM - divots on gingival-third of lingual surface and middle-third of labial surface; MI - divots on middle-third of lingual surface and incisal-third of labial surface; MM - divots on middle-third of lingual surface and middle-third of labial surface. Aligners (n = 30/model) were fabricated using a 0.75 mm thick polyethylene terephthalate material and Biostar® machine following the manufacturer's recommendations. A one-way MANOVA followed by one-way ANOVA (α = 0.05) was utilized to test effect of models on buccolingual force (Fy) and mesiodistal moment (Mx) at 0.20 mm of lingual displacement of the right maxillary central incisor. Mean Mx for GI (-5.68 ± 7.38 Nmm), GM (3.75 ± 5.54 Nmm), MI (-4.27 ± 1.48 Nmm) and MM (1.96 ± 0.99 Nmm) models showed statistical differences between GI and GM, GI and MM, GM and MI and MI and MM. GI exerted the largest Fy (1.87 ± 0.75 N) followed by GM (1.10 ± 0.47 N), MI (0.70 ± 0.23 N) and MM (0.28 ± 0.08 N) with significant differences between GI and GM, GI and MI, GI and MM and GM and MM models. Vertical divot placement on a right central incisor had a significant effect on aligner biomechanics. Buccolingual forces exerted by models GI, GM and MI were within the range suggested by literature for bodily tooth movement without major root tipping for GM and MI models.

Comparative Assessment of the Efficacy of Newly Designed Multiple Variability Loop and Opus Loop for Anterior en Masse Retraction in Orthodontics: A Finite Element Study.

Introduction Two different mechanisms are used to close the space after extractions, i.e., friction/sliding mechanics and frictionless/loop mechanics. The focus of this study is on space closure using frictionless or loop mechanics, which utilize loops to achieve the desired tooth movement. Loops are designed to increase the resiliency of the archwire so that the ideal moment-to-force ratio (M/F) of 8:1 to 10:1 for bodily tooth movement can be obtained. By incorporating various loop designs, the resiliency of archwires may be increased, and an ideal M/F ratio can be obtained. Method Different pre-activation bends were incorporated in the titanium molybdenum alloy (TMA) wire at alpha (canine side) and beta (premolar side), respectively. A total of 36 finite element method (FEM) models were prepared with and without pre-activation bends to evaluate the moment-to-force ratio. Result The results obtained from the finite element method (FEM) analysis provided valuable insights into the force and moment generated during activation while retracting the tooth. Specifically, the alpha bend at 15 degrees and the beta bend at 20 degrees produced the most desirable results for generating moments on the anterior and posterior teeth, respectively. Conclusion To ensure the proper utilization of the multiple variability (MV) loop, we recommend its preparation using a 0.019 x 0.025-inch TMA wire. This selection will maximize the loop's capabilities and enhance its performance in achieving the desired tooth movement.

Comparison of stainless steel and titanium-molybdenum alloy closing loop archwires using numeric simulation model based on finite element method

The objective of this study was to determine and compare the moment-to-force (Mc/F) ratio and the type of tooth movement generated in the anterior and posterior segments in orthodontic space closure with stainless steel and titanium-molybdenum alloy loop archwires. Three-dimensional model of the maxilla from which the first premolar was extracted, 18 × 25-mm slot stainless steel brackets, and 16 × 22-mm stainless steel and β titanium-molybdenum alloy (TMA) closing loop archwires with anterior gable bend of 15° and posterior gable bend of 25° were constructed. The archwires were engaged in the brackets, and 1-mm activations were carried out, which were repeated 5 times. The anterior and posterior segment Mc/F ratio and the type of tooth movement generated by the 2 wires were compared. It was found that the Mc/F ratio for the anterior segment was approximately 5 mm, and for posterior teeth was approximately 10 mm for both stainless steel and TMA closing loop archwire. The anterior teeth exhibited controlled tipping, whereas the posterior teeth showed bodily tooth movement, which was in accordance with the Mc/F ratio that was obtained. The Mc/F ratio and the type of tooth movement exhibited by stainless steel and TMA closing loop archwires were similar in both anterior and posterior segments.

Cephalometric evaluation of deep overbite correction using anterior bite turbos.

To evaluate the outcome of treating deep overbite (OB) using anterior bite elevators concurrently with a pre-adjusted edgewise appliance. The Case Western Reserve University (CWRU) cephalometric analysis was used to isolate tipping movement of upper (TUI) and lower incisors (TLI), bodily tooth movement of upper (BUI), and lower incisors (BLI), as well as vertical skeletal changes in the anterior region of the maxilla (MXSK) and mandible (MNSK). Thirty treated subjects were examined at pretreatment (T1) and posttreatment (T2) and compared to an untreated control group matched on age, sex, and Angle malocclusion from the Bolton Brush Growth Study Collection (CWRU, Cleveland, Ohio). Overbite (OB) in the treated group was decreased significantly (P < .001) (-5.6 mm) compared to controls. Statistically significant (P < .001) changes were found for BUI (-0.7 mm), TUI (0.9 mm), TLI (-1.4 mm), BLI (-1.1 mm), and MNSK (-1.6 mm). Most of the overbite correction was in the lower arch and included tipping and intrusion of the lower incisors along with an increase in lower vertical facial height. Deep OB correction was achieved efficiently using anterior bite elevators with pre-adjusted edgewise appliance. Correction using bite turbos would be a treatment option for individuals presenting with decreased lower facial height and deep bite.

Effect of trimming line design and edge extension of orthodontic aligners on force transmission: A 3D finite element study

ObjectivesTo investigate in a numerical study the effect of the geometry and the extension of orthodontic aligner edges and the aligner thickness on force transmission to upper right central incisor tooth (Tooth 11). MethodsA three-dimensional (3D) digital model, obtained from a 3D data set of a complete dentulous maxilla, was imported into 3-matic software. Aligners with four different trimming line designs (scalloped, straight, scalloped extended, straight extended) were designed, each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were exported to a finite element (FE) software (Marc/Mentat). A facial 0.2 mm bodily malposition of tooth 11 was simulated. ResultsThe maximum resultant force was in the range of (7.5 - 55.2) N. The straight trimming designs had higher resultant force than the scalloped designs. The resultant force increases with increasing the edge extension of the aligner. The normal contact forces were unevenly distributed over the entire surface and were concentrated in six areas: Incisal, Mesio-Incisal, Disto-Incisal, Middle, Mesio-Cervical, and Disto-Cervical. The resultant force increases super linearly with increasing thickness. ConclusionsThe design of the trimming line, the edge extension, and the thickness of the aligner affect significantly the magnitude of the resultant force and the distribution of normal contact force. The straight extended trimming design exhibited better force distribution that may favor a bodily tooth movement. Clinical relevanceA straight extended trimming design of an orthodontic aligner may improve the clinical outcomes. In addition, the manufacturing procedures of the straight design are much simpler compared to the scalloped design.

Comparison of Maxillary Canine Retraction Using Split-Mouth Design With Dual Force Cuspid Retractor and T-loop Segmental Arch: A Split-Mouth Randomized Clinical Trial.

Introduction This study was designed to explore the differences between two frictionless mechanics for canine retraction i.e., dual force cuspid retractor and T-loop segmental arch. T-loop for canine retraction creates a biomechanical system to deliver a predetermined force and a relatively constant moment-to-force ratio whereas dual force cuspid retractor uses power arms on buccal as well as palatal aspects for canine retraction. Bodily tooth movement can be achieved by both methods, but in this study, our main focus was to reduce the canine retraction timing with better three-dimensional control. Method This split-mouth study was conducted on a total of 20 cuspids of ten patients (five male and five female). Where one side of the arch was selected for T-loop and the other side for dual force cuspid retractor, randomly. Inclusion criteria for this study were; no congenitally missing teeth (excluding third molar), class I or class II molar relationship, no previous history of orthodontic treatment, good oral periodontal status, patients in whom extraction of maxillary first premolar during treatment was indicated. Both groups were compared for the duration of canine retraction, anchorage loss; tipping, and rotation of cuspid and molar, individually, after retraction. Result The result of this study showed that the duration of canine retraction was significantly less in group one, i.e., dual force cuspid retractor 73.8 ± 12.38 days, than in group two, i.e., T-loop 109.4 ± 16.71 days. The anchorage loss in group one was 0.60 ± 0.61 mm and that in group two was 2.40 ± 0.87 mm. Also, the amount of tipping and rotation of the cuspid and molar individually was significantly lesser in group one than in group two. Conclusion In this study, the dual force cuspid retractor shortens the duration of canine retraction with better three-dimensional control and better anchorage preservation when compared to T-loop.

Effect of the Maxillary Sinus on Tooth Movement during Orthodontics Based on Biomechanical Responses of Periodontal Ligaments

The maxillary sinus is a common anatomic limitation for orthodontic tooth movement. The effect of orthodontic forces on a particular anatomy can be studied using finite element analysis (FEA). Our study aimed to determine the effect of different tooth penetration depths into the maxillary sinus floor (MSF) on the orthodontic force system for bodily tooth movement. Using the cone-beam computed tomography of a patient with low MSF, we modeled the geometry of canine, premolar, and molar teeth with their periodontal ligaments and the alveolar bone surrounding them. The models were manually modified to simulate different root penetration depths. Thereafter, the center of resistance and stress distributions for teeth penetrating into the MS were determined using FEA. Moreover, the force systems for teeth with a low MSF to varying degree were evaluated based on the FEA results. During orthodontic tooth movement, the individual differences in the periodontal anatomy should be considered. The CR position decreases with the penetration depth, while the average hydrostatic stress in the PDL increases rapidly. In this paper, we present the correction coefficients of the orthodontic force and moment for a tooth penetrating into the MSF, which is necessary for personalized treatment planning.

Effect of archwire plane and archwire size on anterior teeth movement in sliding mechanics in customized labial orthodontics: a 3D finite element study

BackgroundThe aim of this study was to evaluate anterior teeth movement with different archwire planes and archwire sizes during space closure with and without miniscrew in sliding mechanics.MethodsA 3D finite element method was applied to simulate anterior teeth retraction with and without miniscrew and power arm. Initial displacements and pressure stresses of periodontal tissue in anterior teeth were calculated after the teeth were applied with retraction forces with different archwire planes and archwire sizes.ResultsHigh archwire plane showed better torque control of anterior teeth in both sliding mechanics. With intramaxillary retraction, anterior teeth showed lingual tipping and extrusion movement, whereas larger-size archwires did not reduce it. In miniscrew sliding mechanics, anterior teeth showed labial tipping and intrusion movement. Compared with intramaxillary retraction, the retraction force produced less pressure stress on periodontal tissue in miniscrew sliding mechanics with long power arm.ConclusionsHigher archwire plane is conducive to anterior teeth torque control. In order to achieve the bodily movement of the anterior teeth during space closure, it is more important to choose the appropriate method (miniscrew sliding mechanics with long power arm), instead of increasing the size of the archwire.

Treatment of generalized spacing with clear aligner therapy: Report of a case

Clear Aligners are becoming popular among patients in recent years because of its invisible nature , comfort to wear, less orthodontic emergencies and better hygiene control. However proper case selection is vital for the success. With the better understanding of aligner biomechanics and improvement in aligner materials and attachment design, more complex teeth movement is also possible with clear aligners. As there is always controversy on whether aligners cause tipping or bodily tooth movement, In this case report, a skeletal class I patient with generalized spacing in maxilla and mandible is presented which is treated effectively by bodily movement of incisors.

Efficient Design of a Clear Aligner Attachment to Induce Bodily Tooth Movement in Orthodontic Treatment Using Finite Element Analysis.

Clear aligner technology has become the preferred choice of orthodontic treatment for malocclusions for most adult patients due to their esthetic appeal and comfortability. However, limitations exist for aligner technology, such as corrections involving complex force systems. Composite attachments on the tooth surface are intended to enable active control of tooth movements. However, unintended tooth movements still occur. In this study, we present an effective attachment design of an attachment that can efficiently induce tooth movement by comparing and analyzing the movement and rotation of teeth between a general attachment and an overhanging attachment. The 3D finite element modes were constructed from CBCT data and used to analyze the distal displacement of the central incisor using 0.5- and 0.75-mm-thick aligners without an attachment, and with general and overhanging attachments. The results show that the aligner with the overhanging attachment can effectively reduce crown tipping and prevent axial rotation for an intended distal displacement of the central incisor. In all models, an aligner with or without attachments was not capable of preventing the lingual inclination of the tooth.

Effect of Magnet Position on Tipping and Bodily Tooth Movement in Magnetic Force-Driven Orthodontics.

The goal of our study is to launch magnetic force-driven orthodontics. This continuous study investigated the influence of magnet position on tipping and bodily tooth movement, using 3D printing technology and digital analysis. Orthodontic typodont models (TMs) for space-closure were 3D printed to mimic maxillary central incisors. Nd-Fe-B magnets were placed in the middle third (Model-M), and the cervical third (Model-C), of the tooth. TMs, before and after movement, were digitally scanned and superimposed. The 3D digital coordinates (X, Y, and Z axes), and rotations (yaw, pitch, and roll) of the tooth crown and root, were calculated and compared between the two magnet position settings. Model-M showed higher rates of movement, but more rotation than Model-C (p < 0.01). The root apex of Model-M moved in the opposite direction of the crown (R = −0.29), indicating tipping movement. In contrast, the crown and root apex moved in the same direction (R = 0.56) in Model-C, indicating bodily movement. These patterns were confirmed in a typodont model of a moderate crowding case. The results validated that modifying the magnet position increased the amount of bodily tooth movement, and decreased rotation/tipping in an ex vivo setting.

A novel and simple design of the closing loop producing optimal force magnitude and moment-to-force ratio for en-masse retraction of anterior teeth

ABSTRACT Purpose: The aim of this study was to clarify the mechanical conditions of loop activation that produce the optimal force system allowing controlled movement of the anterior teeth. Materials and Methods: The closing loop examined in this study was a 10-mm-high teardrop type bent from a 0.017 × 0.025-inch stainless steel archwire. A loop design that can generate a high moment-to-force (M/F) ratio and the optimal force magnitude was investigated by varying the rate of the cross-sectional reduction of the loop apex, the amount of loop activation and the degree of gable bend. Forces and moments acting on closing loops were calculated using structural analysis based on the tangent stiffness method. Results: A force magnitude of 302 g and an M/F ratio higher than 10 (sufficiently high to achieve bodily movement of the anterior teeth) could be produced when the thickness of the cross-section of a 10-mm-high teardrop loop was reduced by half for a distance of 3 mm from the apex and a gable bend of 30° was incorporated into the loop. Conclusions: The optimal force magnitude and M/F ratio for achieving controlled tipping or bodily movement of the anterior teeth can be produced by partially reducing the thickness of the teardrop loop, and by placing a gable bend of 20° to 30° in the 0.018-inch bracket slot system.

Governing the Friction in Fixed Orthodontic Appliance

: Friction is defined as the force that resists a movement when objects move tangentially against each another. Various forces arise, when two surfaces which are in contact slide against one another. An orthodontist has various difficulties related to friction specially with sliding mechanics and has to deals with it successfully to provide effective tooth movement. During Orthodontic treatment, sliding mechanics is used widely. Friction generated at the bracket/archwire interface is one of the disadvantages of this mechanics, which reduces the quality of desired orthodontic movement acquired. Both clinicians and scientists have an interest in the role of friction in Orthodontics, due to its application. As per clinical studies, the resistance to bodily tooth movement by sliding has far too less to do with friction. It is mainly a binding-and-release situation that is similar to conventional and self-ligating brackets.

Effects of 6 different chemical treatments on force kinetics of memory elastic chains versus conventional chains: An in vitro study

Effects of different oral hygiene controls on force kinetics of memory elastic chains are not assessed adequately or in the case of many oral care products, non-existent. This study assessed these. This in-vitro study was performed on 647 observations of 132 elastic chains assessed at 5 intervals. In each of the treatments (artificial saliva, fluoride, OralB mouthrinse, whitening OralB mouthrinse, toothpaste, and whitening toothpaste), 11 memory and 11 conventional chains were tested. Chains were stretched for 100%; their initial force was measured (g), and immersed in artificial saliva at 37°C. For treatments other than artificial saliva, the specimens were removed from the saliva twice daily and the main treatment was applied. After washing with distilled water, they were immersed back in artificial saliva. At the days 1st, 7th, 14th, and 28th, their force was re-measured. Data were analysed statistically (α=0.05). Force degradation of elastic chains was observed in both memory/conventional types (P=0.000) although memory chains showed slightly less declines especially in the beginning days. The interaction of treatment and time was significant (P=0.000) meaning that different treatments caused different rates of force decay, with fluoride having the fastest drop rate followed by whitening toothpaste. However, the difference among 5 intervals of time was not significant (P=0.569). When elastic types were assessed separately, this variable as well became significant (P≤0.002). One-sample t-test showed that all final residual forces (28th day) were either above 150g or at its level. Chain force degrades over time but stays sufficient for bodily tooth movement after 4 weeks. Memory chains are preferable as they provide greater forces for longer durations. Fluoride mouthwash followed by whitening toothpaste cause the most rapid declines. Both chain types still retained adequate forces after 4 weeks, even after treatment with fluoride or whitening toothpaste.

Complex orthodontic-surgical rehabilitation of adults with malocclusions and deformations in dentition

The aim of the study was the development and substantiation of the method of orthodontic treatment of patients with malocclusions and deformities of dentoalveolar arches with the combined use of braces, orthodontic miniscrew, piezo-surgical corticotomy or laser corticotomy to improve the efficiency and reduce the time of complex treatment. The results of complex rehabilitation of 80 adult patients with dentoalveolar anomalies and deformities of dentition are presented. As a result of the orthodontic treatment of patients who underwent piezo-surgical corticotomy the bodily movement of the posterior teeth in the area of the previously removed tooth was achieved. After piezo-surgical or laser corticotomy the rate of tooth protraction remained elevated for 3 to 5 months (on average 0.3±0.5 mm/month), then gradually decreased. Piezo-surgical corticotomy led to a decrease in bone density, which was measured on the Hounsfield scale. As a result of orthodontic treatment in patients who underwent laser corticotomy an expansion of the upper jaw and normalization of occlusion in the transversal and sagittal directions was achieved: in the region of the hard palate by 7.1±0.4 mm; in the region of the alveolar bone by 6.5±0.5 mm; in the region of the roots of molars by 6.4±0.9 mm; in the area of crowns of molars by 8.3±0.7 mm. It was found that the combined use of piezo-surgical corticotomy and orthodontic miniscrews improve the efficiency and reduce the duration of orthodontic treatment by 3 to 6 months.

Evaluation of lower anterior dental changes in patients treated with self-ligating brackets

The aim of this study was to evaluate and compare changes in linear distance and inclination of lower incisors and canines and intercanine distance after a 30 months orthodontic treatment with self-ligating appliances. Seven patients were treated orthodontically with a Roth prescription passive self-ligating bracket. To perform the measurements and comparisons, CBCT scans were taken before the start of the orthodontic treatment (T1) and after a period of 30 months treatment (T2). The following measurements were performed: (1) the lower incisors and canines inclination in relation to the mandibular plane, (2) intercanine linear distance in millimeters and (3) linear distance in millimeters of the incisal and apical part of lower anterior teeth to a plane (POGM) passing through pogonion point and perpendicular to the mandibular plane. No significant difference were observed between T1 and T2 for canine inclination (p=0.835), incisors inclination (p=0.149), canine incisal distance to POGM (p=0.423) and incisors incisal distance to POGM (p=0.966), however canine apical distance (p=0.049) and incisors apical distance (p=0.002) to POGM was lower at T1 than at T2. The intercanine distance was significantly lower (p=0.022) at T1 when compared to T2. The use of passive self-ligating brackets in orthodontic treatment to solve 4mm tooth crowding were able to produce dental arch expansion by bodily tooth movement.

Resolving differences between animal models for expedited orthodontic tooth movement.

To highlight differences in commonly used animal models of orthodontic tooth movement (OTM). Narrative review. A critical review of the literature on animal models has become increasingly important in the last decade as methods to increase the rate of tooth movement have been intensely sought. We provide a review focusing on the rodent and canine models for expedited OTM and describe the challenges in extrapolation of the results to the clinical practice of orthodontics. We review and contrast the two (rodent, canine) most commonly used animal models for OTM. We then describe animal models to study bone adaptation, remodelling and modelling, which are keys events in describing and quantifying OTM. Understanding the differences between animal models and their adaptation biology as it relates to OTM is key to make valid conclusions. The rodent model can be used to understand the initial phases of tooth movement. Unlike the dog model, the rodent model does not lend itself to understand prolonged adaptation in response to bodily tooth movement. Extrapolation of rate of tooth movement to humans is more challenging from rodent model data.

Effect of gingival fibroblasts and ultrasound on dogs' root resorption during orthodontic treatment.

Objectives:To investigate the effect of using osteogenic induced gingival fibroblasts (OIGFs) and low intensity pulsed ultrasound (LIPUS) on root resorption lacunae volume and cementum thickness in beagle dogs that received orthodontic tooth movement.Materials and Methods:Seven beagle dogs were used, from which gingival cells (GCs) were obtained and were induced osteogenically to produce OIGFs. Each third and fourth premolar was randomly assigned to one of the five groups, namely, LIPUS, OIGFs, bone morphogenetic protein-2 (BMP-2), OIGFs + LIPUS, and control. All groups received 4 weeks of bodily tooth movement, then LIPUS-treated groups received LIPUS for 20 min/day for 4 weeks, and OIGFs groups received an injection of OIGFs near the root apex. Microcomputed tomography analysis was used to calculate root resorption lacunae volume and histomorphometric analysis was performed to measure the cementum thickness of each root at 3 root levels on compression and tension sides.Results:There was no significant difference in resorption volume between the treatment groups. OIGFs + LIPUS increased cementum thickness (P > 0.05) in third premolars near the apex, and LIPUS increased cementum thickness (P > 0.05) in fourth premolars near the apex. Furthermore, BMP2 increased cementum thickness at the coronal third at the compression side.Conclusion:OIGFs, LIPUS, and BMP-2 can be potential treatments for orthodontically induced root resorption, however, improvements in experimental design and treatment parameters are required to further investigate these repair modalities.

Effect of increasing the vertical intrusive force to obtain torque control in lingual orthodontics: A three-dimensional finite element method study.

Biomechanical differences between lingual and labial orthodontics (LiO and LaO). To investigate the effects of intrusive forces in lingual technique during retraction treatment mechanics. Intrusive forces act differently in both techniques because of the different location of force vectors in relation to the center of resistance. Increasing the vertical intrusive force is one of the methods routinely used to prevent the uncontrolled tipping and obtain bodily tooth movement in LaO. However, its effects in lingual technique need to be investigated to derive at an optimal treatment mechanics. Finite element method which has been successfully used to simulate tooth movement and optimize orthodontic mechanics effectively was used in this study. An accurate model of the upper central and lateral incisors with the surrounding structures was developed, and the "ANSYS" version 7.0 software was used for analysis. Intrusive forces as high as 3.6N was required to obtain translation in LiO that too in an undesirable direction. Efforts to obtain torque control by increasing the intrusive force only would not be successful. Forces that produce a translation in LaO tends to produce uncontrolled tipping in lingual technique. To obtain adequate torque control in lingual technique, a combination of the reduction in horizontal retraction forces, increased lingual root torque application, and increase in vertical intrusive forces is desirable.