Lingual Force Research Articles

Effect of thermomechanical ageing on force transmission by orthodontic aligners made of different thermoformed materials: An experimental study.

Investigating the impact of thermal and mechanical loading on the force generation of orthodontic aligners made from various thermoplastic materials and different compositions. Five distinct materials were utilized including, three multi-layer (Zendura FLX, Zendura VIVA, CA Pro) and two single-layer (Zendura A and Duran). A total of 50 thermoformed aligners (n = 10) underwent a 48-hour ageing protocol, which involved mechanical loading resulting from a 0.2 mm facial malalignment of the upper right central incisor (Tooth 11) and thermal ageing through storage in warm distilled water at 37°C. The force exerted on Tooth 11 of a resin model was measured both before and after ageing using pressure-sensitive films and a biomechanical setup. Before ageing, pressure-sensitive films recorded normal contact forces ranging from 83.1 to 149.7 N, while the biomechanical setup measured resultant forces ranging from 0.1 to 0.5 N, with lingual forces exceeding facial forces. Multi-layer materials exhibited lower force magnitudes compared to single-layer materials. After ageing, a significant reduction in force was observed, with some materials experiencing up to a 50% decrease. Notably, multi-layer materials, especially Zendura VIVA, exhibited lower force decay. The force generated by aligners is influenced by both the aligner material and the direction of movement. Multi-layer materials exhibit superior performance compared to single-layer materials, primarily because of their lower initial force, which enhances patient comfort, and their capability to maintain consistent force application even after undergoing ageing.

In vitro study examines posterior torque impact on 3D mechanics of anterior teeth in clear aligner treatment

IntroductionThis study utilizes investigate the impact of posterior torques on the three-dimensional force exerted on the lower anterior teeth during the retraction in orthodontic clear aligners treatment.MethodsFour groups of mandibular dental arch light-cured resin models will be created, including: mandibular posterior teeth with standard torque, mandibular posterior teeth with labial torque, and mandibular posterior teeth with lingual torque. Each group will consist of 12 sets of clear aligners. The aligners will be worn, and measurements will be taken using the six-axis measurement platform to evaluate the three-dimensional force exerted on the lower anterior teeth under various initial torques applied to the mandibular posterior teeth. SPSS 26.0 used for ANOVA analysis, α = 0.05 significance level.ResultsComparing mandibular posterior teeth with standard torque to those with labial torque, no statistically significant changes were observed in buccolingual force. In the mesiodistal direction, mandibular incisors exhibited a significant decrease in distal force, while canines showed a significant increase. Both findings had a significance level of P < 0.05; Lingual torque on mandibular posterior teeth, compared to standard torque, led to a significant increase in lingual force for incisors and a significant increase in labial force for canines in the buccolingual direction (P < 0.05). Additionally, mandibular incisors exhibited a significant decrease in distal force in the mesiodistal direction (P < 0.05).ConclusionVarying initial torques on mandibular posterior teeth significantly impact force on lower anterior teeth. Labial torque reduces lingual force on incisors and increases distal force on canines. Lingual torque increases lingual force on incisors and labial force on canines.

Assessment of mechanical characteristics of polyetheretherketone as orthodontic fixed lingual retainers

Background/purposePolyetheretherketone (PEEK) is known for its strength, flexibility, biocompatibility, and potential as a replacement for metals in dental appliances; however, uncertainty remains about the mechanical characteristics and dimensions of PEEK-made orthodontic fixed lingual retainers (FLRs). This study aimed to determine the optimal shape of PEEK-made orthodontic FLRs using the finite element method (FEM) and the three-point bending test (TPBT). Materials and methodsSeventy-five three-dimensional PEEK rod-shaped models were created, which included five thicknesses (0.4, 0.6, 0.8, 1.0, and 1.2 mm), five widths (0.7, 0.9, 1.1, 1.3, and 1.5 mm), and three cross-sectional shapes (rectangular, oval, and hemielliptical). A 0.9-mm (0.036-inch) stainless steel wire (SSW) was used as a control and the FEM was used to determine six optimal dimensions among the PEEK models. The selected models were then fabricated and subjected, along with the SSW, to the experimental TPBT to assess their mechanical responses against lingual and biting pressures. ResultsThe FEM analysis revealed that Von Mises stresses on the PEEK models decreased with an increase in width and thickness. Six optimal shapes of PEEK models were chosen based on acceptable lingual and biting stresses as well as patient comfort compared to the SSW. Furthermore, PEEK models showed significantly lower deformation during the 3.1-mm deflection test than did the SSW, while no notable differences were observed among different sizes of PEEK models. The hemielliptical PEEK model with a thickness of 1.0 mm and width of 1.5 mm was found to be mechanically robust enough to withstand lingual forces, while none of the PEEK models, including the SSW, were able to resist biting forces. ConclusionWithin the limitations of this in vitro study, PEEK-made orthodontic FLRs with a hemielliptical cross-sectional shape and a thickness-to-width ratio of 1.0:1.5 would be suitable for use as orthodontic FLRs.

3D Finite Element Study of the Physiological Anchorage Control Concept on Anchorage Molars in Lingual Orthodontics.

To study the effect of the physiological anchorage control concept on anchorage molars in lingual and labial orthodontic techniques. Three-dimensional finite element models, including the right maxillary first molar, periodontal ligament, alveolar bone, and buccal tube, were established. The models were divided into the McLaughlin-Bennett-Trevisi (MBT™) straight-wire model with 0-degree maxillary first molar axial inclination and the physiologic anchorage Speewire system (PASS) model with -7-degree maxillary first molar axial inclination. Simulated sliding retraction forces (1 N, 1.5 N, and 2 N) were loaded on the buccal side and lingual side, and retraction forces (0.5 N, 0.75 N, and 1 N) were loaded on the buccal and lingual sides simultaneously. The displacements, principal stresses, and von Mises stresses of the periodontal ligament under different conditions were derived. The anchorage molars showed different degrees of rotation, tipping, intrusion, and extrusion. As the force increased, these displacement trends also increased. The mesial displacement of the buccal + lingual force loading was less than that of the other two groups. Under the same force load method, the mesial displacement of the PASS group was less than that of the MBT group. Tilt movement increases the tensile stress of the distal cervical margin and root mesial apical third and the compressive stress of the mesial cervical margin and root distal apical third. The maximum stress of the periodontal ligament was less than that of the other two groups when the lingual force was loaded. The physiological anchorage control concept in lingual orthodontics provides better sagittal anchorage control than in labial orthodontics, but there is no significant difference numerically. Attention should be given to the control of torsion, torque, and arch width. Tilt movement increases the PDL stress of the cervical margin and root apical third. The sliding retraction force should be loaded lingually to maintain the force value of 1∼1.5 N.

In Vitro Comparison of Different Invisalign® and 3Shape® Attachment Shapes to Control Premolar Rotation.

Aim: To evaluate in vitro the differences of various Invisalign® attachments in their effectiveness during derotation of an upper second premolar in terms of forces and moments created and compare them to the 3Shape® box attachment as well as to no attachment at all. Materials and Methods: A Force System Identification (FSI) machine, comprising two load sensors, was used in this study. Sensor 1 was connected to the test tooth (i.e. upper second premolar) carrying a different attachment design, and the fixed sensor (Sensor 2) was connected to the base model. Once the corresponding aligner was passively seated on the teeth, 12 different setups (i.e. 11 different attachments and one setup with no attachment at all) were tested by rotating the test tooth 4.5° mesially and 4.5° distally, in increments of 0.45°. Results: The vertical rectangular attachments were able to generate the highest derotational moment on both mesial and distal rotations but also received the most side effects (intrusive force, torque, and tipping). The no-attachment setup performed least favorably in terms of derotational ability but exhibited the least side effects. In the y-axis, all attachments received a buccal root torque with a lingual force during disto-rotation and a lingual root torque with a buccal force during mesio-rotation. Conclusion: Attachments are necessary for derotating an upper second premolar. An aligner incremental change of more than 1° derotation can generate high moments. The vertical rectangular attachments perform best in derotations; however, they exhibit the most side effects. Finally, despite presenting the least side effects, derotation of a premolar with no attachment is not as efficient.

Fracture Resistance of Incisal Tooth Fragment reattached with different Materials and Preparation

The purpose of this study is to analyze the fracture resistance of reattached tooth according to the resin materials and tooth preparation type under physiological conditions. Uncomplicated crown fracture in the oblique direction was reproduced on the extracted 64 anterior teeth. Depending on the composite resin material, reattachment was performed using a flowable resin and a packable resin. Depending on retentive forms, reattachment was performed using simple reattachment, 1.0 mm × 1.0 mm labial chamfer bevel, 1.0 mm × 1.0 mm lingual chamfer bevel and 1.0 mm × 1.0 mm circumferential bevel. A load was applied to the palatal surface of the tooth using a universal testing machine at an angle of 125 degree, which is the interincisal angle of normal children. Under the masticatory pressure condition, fracture resistance of lingual chamfer groups was 28.28 ± 7.41 MPa and 27.54 ± 4.45 MPa, which was significantly higher than those of simple reattachment groups, 17.21 ± 5.87 MPa and 20.10 ± 6.00 MPa, in both flowable and packable resin groups. When considering the lingual force similar to masticatory pressure, the fragment retention was significantly improved when the lingual chamfer was formed compared to the simple reattachment. Clinicians may consider the design of the lingual chamfer in order to improve fracture resistance to masticatory pressure during fragment reattachment.

Reciprocal force generated by two sliding jigs: An alternative mechanic for molar protraction

Objective: When a first molar is lost, orthodontic replacement with second and third molars would be an excellent treatment option. There are some side effects that tend to occur during molar protraction, such as mesial tipping of molar that could increase the time required to correct. These side effects can be avoided by understanding the biomechanical variables affecting molar protraction. The author tries to present the modification of sliding jigs, instead of the power arm function, with additional of lingual force, for molar protraction.Methods: This case report describes the management of a 23-years-old woman who was missing left mandibular first molar, had class III skeletal profile, and anterior crossbite. After anterior crossbite correction, the left mandibular first molar extraction spaces were closed by protraction of the second and third molars. Mesial tipping was detected in the early protraction phase when using conventional method. Consequently, uprighting procedure was done and protraction was continued using reciprocal force generated by two sliding jigs and lingual buttons to achieve bodily movement of tooth.Results: The result was excellent, the space was closed without tipping and rotation.Conclusion: The presented article provides an alternative mechanic for molar protraction using sliding jigs and how it can be designed to achieve predictable result.

The influence of tongue strength on children's performance in computer games reliant on lingual force generation.

Oral motor exercises, for recovering tongue strength, can be integrated with computer games to increase motivation, especially for treatments in children. The aim of this study was to investigate the influence of tongue strength on motor performance in computer games reliant on lingual force generation. An observational study was carried out at a speech-language pathology outpatient university clinic. Twenty participants (10 with normal tongue strength and 10 with reduced tongue strength) aged 8-13years used an intra-oral joystick controlled by the tongue to play six computer games during which they had to reach targets that appeared on the screen. Motor performance was measured by the number of attempts to score and the time during which the target force was maintained. Tongue motor performance was compared between groups and across directions of tongue movement, resistance force levels, order of target appearance, continuous force application time on the target, age and sex. Children with normal tongue strength had a lower number of attempts to score (P=.014) and maintained the target force for longer periods (P=.002) than those with reduced tongue strength. The performance was better for both groups (a) in the downward direction compared with the performance in other directions, (b) in games with the lowest resistive force level (0.5N) compared to those with other levels of resistive force and (c) in the second and third rounds compared with the first round. There were no gender-related differences in performance. Older participants performed better than younger participants. Tongue strength, direction of movement, force to reach the target, time of continuous force application, order of target appearance and age influenced tongue motor performance.

Design and Development of a Novel Oral Care Simulator for the Training of Nurses.

A Novel Oral Care Simulator was designed and developed to measure and visualise the facial and lingual forces exerted on teeth by the action of tooth brushing, considering the irregular geometry and structural composition of human dentition and the emulation of the realistic biomechanical deflection of the teeth. FEA simulations were carried out on a central incisor under facial loading and an appropriate force sensing mechanism was designed. An anatomically accurate mandibular jaw and 16 teeth were 3D printed, on which 16 force sensing structures were embedded. The signals from the sensors were amplified using a multichannel signal amplifier built using instrumentation amplifiers which were then visualised through a GUI. The developed simulator is capable of indicating the magnitude of a force upto 15 N exerted on to the facial and lingual surfaces of teeth at a frequency of 60Hz and above and it is capable of alerting the user if the force exceeds a pre-specified threshold. The designed force sensing mechanism considers the irregular geometry and structural composition of human dentition in measuring the facial and lingual forces. It provides a reliable feedback by indicating the force and emulating the realistic biomechanical deflection of teeth. Nurses who care for the disabled, elderly and sick have explicitly stated the requirement for a simulator to train themselves on brushing the teeth of their subjects as their incorrect technique can cause longterm dental damage, for which a device has not been developed to date.

Comparison of Rate of En masse Retraction and Anchorage Loss in Conventional Labial Appliance with Labial and Lingual Force: A Clinical Study

Comparison of Rate of En masse Retraction and Anchorage Loss in Conventional Labial Appliance with Labial and Lingual Force: A Clinical Study

Evaluation of the load system produced by a single intrusion bend in a maxillary lateral incisor bracket with different alloys.

To evaluate if a 0.5-mm vertical bend applied on an incisor bracket produces movements in other planes and if different wires influence these effects. An acrylic model of a treated patient with brackets passively bonded was attached to an Orthodontic Force Tester, and a load cell was attached to the left lateral incisor. Thirty 0.019 × 0.025-inch archwires were divided into three groups according to their alloy: SS (stainless steel), B-Ti (beta-titanium), and MF (beta-titanium wire coated with nickel-titanium). Step-bends of 0.5 mm high were placed on the lateral incisor bracket using a universal plier, and the forces and moments in three dimensions were statistically analyzed by analysis of variance and Tukey post hoc test. SS produced a larger force (3.4 N) than the B-Ti (1.41 N) and the MF (0.53 N; P < .001). Lingual forces were produced by the SS (0.82 N) and B-Ti (0.31 N) groups, while in the MF group, the force was insignificant. SS produced a mesial force of 0.24 N, while the B-Ti force was insignificant and MF produced 0.09 N. Groups produced different crown-distal tipping moments (SS = 31.48 N-mm, B-Ti = 11.7 N-mm, and MF = 4.55 N-mm) and different crown-buccal tipping moments. SS produced larger moments (3.63 N-mm) than B-Ti (1.02 N-mm) and MF (0.36 N-mm) wires. A mesial-out rotational moment was observed in all groups (SS = 7.17 N-mm, B-Ti = 3.46 N-mm, and MF = 0.86 N-mm). A 0.5-mm intrusion bend produced lingual and mesial side effects. In addition to the distal and buccal crown-tipping moments, there was a mesial-out moment. Compared with SS, B-Ti and MF wires produced lower forces. These more flexible wires showed side effects with lesser intensity.

Comparison of Rate of En masse Retraction and Anchorage Loss in Conventional Labial Appliance with Labial and Lingual Force: A Clinical Study

Aims: The rate of en masse retraction and anchorage loss were compared between labial appliance with lingual force and conventional labial appliance. Subjects and Methods: The sample consists of 14 patients and they were divided into two groups. In Group 1 – labial appliance with lingual force, elastomeric chain was placed from the palatal surface of the canines to the palatal surface of the molars. In Group 2 – labial appliance with labial force, elastomeric chain was placed from the crimpable hook distal to lateral incisor to the molar tube hooks. The rate of en masse retraction and anchorage loss was calculated for both the groups during retraction in dental casts (R 0 , initial; R 1 , 4 weeks; R 2 , 8 weeks; and R 3 , 12 weeks). Statistical Analysis Used: Student's paired t -test. Results: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, i.e., Group 1. The difference of anchorage loss in Group 1 and Group 2 shows t = 4.824 and P value= 0.000, which is statistically highly significant. The difference of rate of retraction in Group 1 and Group 2 shows t = 3.573 and P value = 0.004, which is statistically signifcant. Conclusions: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, thus indicating that this new technique of space closure utilizes biomechanical advantage of lingual force in conventional labial appliance.

In-vivo determination of critical force levels using an intraoral electromechanical device to measure nonpathologic tooth mobility.

An electromechanical device was used to experimentally characterize the movement of a single tooth within the periodontal ligament space. The force magnitude leading to the complete compression of the periodontal ligament is considered a critical force and is designated Fc. We investigated the effectiveness of the electromechanical device to repeatedly determine the critical force magnitude Fc. The study comprised 12 tests conducted on 11 subjects. Alternating labial and lingual forces were applied to a maxillary incisor by the device. The resulting immediate intra-alveolar tooth displacement was recorded in real time. Data processing was used to determine the tooth mobility curve for 193 push-pull cycles. The critical force Fc was mathematically determined for both the labial and lingual displacements of the tooth. The tooth mobility curve could be characterized for all 12 tests. A total of 386 values of Fc were calculated for the 12 different teeth. Values of Fc for each test ranged from 10.47 to 20.18g in the lingual direction, and from 12.56 to 21.72g in the labial direction. The electromechanical appliance was successful in repeatedly determining Fc invivo. The ability to experimentally determine the extent of periodontal ligament compression at a given force magnitude could shed new light on the question of an optimal orthodontic force and open new avenues of orthodontic research and treatment.

Effects of labial and lingual retraction and intrusion force on maxillary central incisor with varying collum angles: A three-dimensional finite elemental analysis

Effects of labial and lingual retraction and intrusion force on maxillary central incisor with varying collum angles: A three-dimensional finite elemental analysis

A finite element analysis of initial stresses and displacements in the tooth and the periodontium in periodontally compromised simulations: Labial versus lingual force application

Introduction: Orthodontics a unique branch in dentistry is inter-related with biology, mathematics and engineering sciences. Biomechanics is fundamental to the practice of orthodontics. Stresses generated at any point during orthodontic treatment are critical in remodeling of bone and type of tooth movement. Aims and Objectives: The aim of the following study is to determine the initial stresses produced in the tooth, periodontal ligament (PDL) and bone when force is applied on the tooth for intrusion and tipping on labial and lingual sides in the presence of varying alveolar bone heights. Materials and Methods: A geometric model generated using AutoCAD (Autodesk, Inc.). Six three-dimensional finite element models of a maxillary central incisor were designed with PDL and varying alveolar bone heights after applying the boundary conditions of the model, force was applied on the tooth. Results: Results were obtained with color coded three-dimensional fringe patterns. Conclusion: Alveolar bone loss causes an increase in the maximum initial stresses relative to the bone heights.

Three-dimensional finite element analysis of maxillary anterior teeth retraction force system in light wire technique

This study aims to construct a three-dimensional finite element model of a maxillary anterior teeth retraction force system in light wire technique and to investigate the difference of hydrostatic pressure and initial displacement of upper anterior teeth under different torque values of tip back bend. A geometric three-dimensional model of the maxillary bone, including all the upper teeth, was achieved via CT scan. To construct the force model system, lingual brackets and wire were constructed by using the Solidworks. Brackets software, and wire were assembled to the teeth. ANASYS was used to calculate the hydrostatic pressure and the initial displacement of maxillary anterior teeth under different tip-back bend moments of 15, 30, 45, 60, and 75 Nmm when the class II elastic force was 0.556 N. Hydrostatic pressure was concentrated in the root apices and cervical margin of upper anterior teeth. Distal tipping and relative intrusive displacement were observed. The hydrostatic pressure and initial displacement of upper canine were greater than in the central and lateral incisors. This hydrostatic pressure and initial intrusive displacement increased with an increase in tip-back bend moment. Lingual retraction force system of maxillary anterior teeth in light wire technique can be applied safely and controllably. The type and quantity of teeth movement can be controlled by the alteration of tip-back bend moment.

Effects of Lingual Effort on Swallow Pressures Following Radiation Treatment.

This article investigated the effects of increased oral lingual pressure on pharyngeal pressures during swallowing in patients who have undergone radiotherapy for head and neck cancer. It was hypothesized that increased oral lingual pressure would result in increased pharyngeal pressures. A within-subject experimental design was used with 20 participants who were status post external beam radiotherapy for head and neck cancer. Participants completed typical swallows and swallows with increased lingual force during manofluoroscopic swallow studies. The swallow condition order was randomized across participants. Manometric data revealed significant differences in swallow pressure by condition at the base of tongue and upper esophageal sphincter sensor locations without significant pressure differences in the lower pharynx. The effortful lingual swallows resulted in higher mean pressures at all locations. The results of this study suggest that use of a maneuver designed to increase oral tongue effort can also increase pharyngeal tongue base pressure. Therefore, therapeutic activities used to generate greater pressure of the oral tongue may also alter pharyngeal response. Further research is needed to determine the direct clinical effect on swallow function for individuals with head and neck cancer.

Finite element analysis of mandibular molar protraction mechanics using miniscrews.

The aim of this study was to determine the most desirable force system to achieve molar protraction from an interdental miniscrew minimizing side-effects. Several iterations of force delivery were simulated through variations in the height of a miniscrew, length of a molar extension arm, and incorporation of a lingual force. A three-dimensional mesh model of the right posterior segment of the mandible was developed from cone beam computed tomography data from a patient missing a first molar. Protraction appliances were constructed using computer-aided design software and integrated with finite element software. After mesh generation, a total of 80 loading conditions were simulated by altering the extension arm length (2-10mm), miniscrew height (0-8mm), and magnitude of protraction force from the lingual side (0-1.5 N). A constant labial force of 1 N was used in all models. As the length of the extension arm increased, mesial tipping decreased, rotation decreased, and buccolingual inclination remained the same without lingual traction force. Lingual traction reduced rotation but increased tipping. Similar trends were observed in all situations despite of the height of the miniscrew. The height of the miniscrew is not as critical in affecting tooth movement during mandibular second molar protraction as the length of the extension arm. The most ideal force system in the model appeared to be the longest extension arm (10mm) with the addition of a lingual force of half or equal magnitude of the labial force.

Comparison of tongue muscle characteristics of preterm and full term infants during nutritive and nonnutritive sucking

BackgroundIndependent oral feeding requires coordination of suck, swallow and breathe and the lingual musculature plays a significant role in this coordinative action. However, clinical benchmarks of lingual function fundamental to successful feeding have not been explored. AimsThe present study tests our model for quantifying infant lingual force and size and compares the muscle measures of interest in two cohorts: healthy full-term infants (FT) (N=5) and healthy preterm infants (PT) (N=6). MethodUsing an instrumented pacifier and bottle nipple, we determined the resultant compressive forces applied to the nipple by the tongue during nutritive (NS) and nonnutritive sucking (NNS). Muscle size was estimated from measures of posterior tongue thickness using ultrasonography. ResultsAfter controlling for weight and post menstrual age, statistically significant differences were found between FT and PT infants beginning to feed for NNS frequency and NS tongue force. Clinically significant differences were detected for NNS tongue force and posterior tongue thickness. Additionally, PT infants demonstrated a significant difference in mean tongue force between NS and NNS and FT infants did not. FT infants demonstrated a significant difference in mean frequency between NS and NNS and PT infants did not. Linear regression indicated that mean posterior tongue thickness alone predicted 55% of the variance in NS force. ConclusionsResults demonstrate the feasibility of our approach and suggest that infant tongue muscle characteristics necessary for successful feeding differ between healthy full term infants and preterm infants who are beginning oral feeding.

Oropharyngeal dysphagia may occur in late-onset Pompe disease, implicating bulbar muscle involvement

Late-onset Pompe disease (presenting after 12 months of age) often presents with limb-girdle and respiratory weakness, but oropharyngeal dysphagia has not been reported previously. A retrospective review of all late-onset Pompe disease patients evaluated in the neuromuscular clinic at Duke University Medical Center from 1999-2010 was performed. Twelve patients were identified and 3 had symptoms of oropharyngeal dysphagia. The medical record was reviewed, including the results of electromyography, videofluroscopic swallow examinations, and motor speech examination including instrumental assessment of lingual force with the Iowa Oral Performance Instrument. Oropharyngeal dysphagia was mild in two cases and severe in one. One of the two patients with mild severity demonstrated oral stage swallow signs; in the other, residual material was observed in the area of the cervical esophagus. In the patient with severe oropharyngeal dysphagia, both the oral and pharyngeal stages of swallowing were affected with penetration and aspiration documented. The degree of swallowing impairment appeared to correlate with overall physical strength and function. Oropharyngeal dysphagia may occur in patients with late-onset Pompe disease, implicating bulbar muscle involvement. Screening for symptoms of dysphagia may help reduce morbidity and mortality, while improving understanding of the late-onset Pompe disease phenotype. Further studies, including examination of the relationship between lingual weakness and oropharyngeal dysphagia, are warranted.