Anchorage Reinforcement Research Articles

Quantitative evaluation of vertical control in orthodontic camouflage treatment for skeletal class II with hyperdivergent facial type

BackgroundIn this study, we sought to quantify the influence of vertical control assisted by a temporary anchorage device (TAD) on orthodontic treatment efficacy for skeletal class II patients with a hyperdivergent facial type and probe into the critical factors of profile improvement.MethodsA total of 36 adult patients with skeletal class II and a hyperdivergent facial type were included in this retrospective case–control study. To exclude the effect of sagittal anchorage reinforcement, the patients were divided into two groups: a maxillary maximum anchorage (MMA) group (N = 17), in which TADs were only used to help with anterior tooth retraction, and the MMA with vertical control (MMA + VC) group (N = 19), for which TADs were also used to intrude the maxillary molars and incisors. The treatment outcome was evaluated using dental, skeletal, and soft-tissue-related parameters via a cephalometric analysis and cast superimposition.ResultsA significant decrease in ANB (P < 0.05 for both groups), the retraction and uprighting of the maxillary and mandibular incisors, and the retraction of protruded upper and lower lips were observed in both groups. Moreover, a significant intrusion of the maxillary molars was observed via the cephalometric analysis (− 1.56 ± 1.52 mm, P < 0.05) and cast superimposition (− 2.25 ± 1.03 mm, P < 0.05) of the MMA + VC group but not the MMA group, which resulted in a remarkable decrease in the mandibular plane angle (− 1.82 ± 1.38°, P < 0.05). The Z angle (15.25 ± 5.30°, P < 0.05) and Chin thickness (− 0.97 ± 0.45°, P < 0.05) also improved dramatically in the MMA + VC group, indicating a better profile and a relaxed mentalis. Multivariate regression showed that the improvement in the soft tissue was closely related to the counterclockwise rotation of the mandible plane (P < 0.05).ConclusionsTAD-assisted vertical control can achieve intrusion of approximately 2 mm for the upper first molars and induce mandibular counterclockwise rotation of approximately 1.8°. Moreover, it is especially important for patients without sufficient retraction of the upper incisors or a satisfactory chin shape.

Evaluation of the Co-Go-Me angle as a predictor in Class II patients treated with Herbst appliance and skeletal anchorage: a retrospective cohort study.

A condylion-gonion-menton (Co-Go-Me) angle threshold of 125.5° has been introduced as a predictive parameter of cephalometric mandibular response in the orthopedic treatment of growing Class II patients with functional appliances, despite some contradictions in the literature. Considering the lack of studies evaluating the role of skeletal anchorage, this study aims to reassess the threshold of 125.5° in the Co-Go-Me angle as a useful predictor in growing skeletal Class II patients treated with acrylic splint Herbst appliance and two mini-screws in the lower arch (STM2). Thirty-five consecutively treated patients (20 males, 15 females; mean age, 11.37 years) with mandibular retrusion were classified into two groups according to their Co-Go-Me baseline values (Group 1, <125.5°; Group 2, >125.5°). The STM2 protocol involved the use of the MTH Herbst appliance with an acrylic splint in the lower arch and two interradicular mini-screws as anchorage reinforcement. Cephalometric analysis was performed by the same operator for each patient at baseline (T0) and at the end of the Herbst phase (T1). The effects of time and group on the variables were assessed by a repeated-measures analysis of variance. The primary research outcome was the difference between the groups in terms of mandibular responsiveness to treatment referred to as the relative difference (T1-T0) in Co_Gn. The mean duration of the treatment was 9.5 months. No statistically significant differences between groups were detected at baseline, except from the expected SN/GoMe° (p < 0.001) and Co-Go mm (p = 0.028). No statistically significant changes between groups, which were caused by the treatment, were found considering the mandibular sagittal and vertical skeletal parameters. Similarly, no statistically significant differences were found in the dental changes between the high-angle and low-angle patients, apart from the upper molar sagittal position (p = 0.013). The 125.5° threshold in the Co-Go-Me value was not a reliable predictive parameter for the mandibular response in growing patients treated with the MTH Herbst appliance and lower skeletal anchorage. Due to its effective control in the sagittal and vertical planes, the STM2 technique might be an appropriate protocol to use in treating skeletal Class II patients, regardless of the growth pattern.

Accuracy of Digital Orthodontic Treatment Planning: Assessing Aligner-Directed Tooth Movements and Exploring Inherent Intramaxillary Side Effects.

Background: The attainment of precise posterior occlusion alignment necessitates a deeper understanding of the clinical efficacy of aligner therapy. This study aims to determine whether the treatment goals defined in the virtual planning of aligner therapy are effectively implemented in clinical practice, with a particular focus on the influence of distalization distances on potential vertical side effects. Methods: In this retrospective, non-interventional investigation, a cohort of 20 individuals undergoing Invisalign® treatment was examined. Pre- and post-treatment maxillary clinical and ClinCheck® casts were superimposed utilizing a surface-surface matching algorithm on palatal folds, median palatine raphe, and unmoved teeth as the stable references. The effectivity of planned versus clinical movements was evaluated. Groupings were based on distalization distances, planned vertical movements, and Class II elastic prescription. Statistics were performed with a two-sample t-test and p-value < 0.05. Results: Clinically achieved distalization was significantly lower than virtually planned distalization, regardless of additional vertical movements, where a lack of implementation was contingent upon the extent of distalization, with no mitigating effects observed with the application of Class II elastics. Intriguingly, no adverse vertical side effects were noted; however, the intended intrusions or extrusions, as per the therapeutic plans, remained unattainable regardless of the magnitude of distalization. Conclusions: These findings underscore the imperative for future investigations to delve deeper into the intricacies surrounding translational mesio-distal and vertical movements, thereby enhancing predictability within orthodontic practice. To facilitate successful clinical implementation of vertical and translational movements via aligners, the incorporation of sliders emerges as a promising strategy for bolstering anchorage reinforcement.

A comparative study on anterior teeth retraction-related hard and soft tissue changes with physiologic anchorage control technique

Aim of this comparative cross-sectional study was to evaluate the effect of anterior teeth retraction and related hard and soft tissue change under physiologic anchorage control in patients with chief complain of protrusive teeth. 68 Class I or II orthodontic patients undergoing four-premolar extraction and requiring maximum or medium anchorage were included. Patients were treated with physiologic anchorage control technique (PASS group, n = 34, 18.6 ± 7.7 years, 10 male and 24 female) and self-ligation technique (Damon group, n = 34, 17.5 ± 5.4 years, 13 male and 21 female), respectively. TADs were used for anchorage reinforcement in Damon group. Pre- and post-treatment cephalograms were collected. Twenty-six skeletal, dental and soft tissue items were measured and analyzed using a blinded method. T test and paired rank-sum test were used for statistical analysis. The baseline characteristics were similar between groups (P > 0.05). After treatment, inter-group comparison showed statistically significant differences in the decrease of skeletal measurements ∠ANB (− 0.73 ± 1.05° in PASS group and − 0.25 ± 0.84° in the Damon group), Wits value (− 2.56 ± 2.29 mm in PASS group and − 0.47 ± 2.15 mm in Damon group) and soft tissue measurement UL-E (− 2.75 ± 1.36 mm in PASS group and − 2.03 ± 1.30 mm in Damon group) and the increase of FCA and Z angle, which was 2.03 ± 2.12°and 9.52 ± 4.78°in PASS group and 0.97 ± 2.12°and 6.96 ± 4.43°in Damon group, respectively (P < 0.05). Our results indicated that significant anterior teeth retraction and profile improvement could be achieved with PASS technique without additional anchorage devices. Appropriate application of physiologic anchorage control could reduce the dependence of TADs for anterior teeth retraction.

The effect of enhanced structure in the posterior segment of clear aligners during anterior retraction: a three-dimensional finite element and experimental model analysis

BackgroundMesial tipping of posterior teeth occurs frequently during space closure with clear aligners (CAs). In this study, we proposed a new modification of CA by localized thickening of the aligner to form the enhanced structure and investigate its biomechanical effect during anterior retraction.MethodsTwo methods were employed in this study. First, a finite element (FE) model was constructed, which included alveolar bone, the first premolars extracted maxillary dentition, periodontal ligaments (PDL), attachments and aligners. The second method involved an experimental model—a measuring device using multi-axis transducers and vacuum thermoforming aligners. Two groups were formed: (1) The control group used common CAs and (2) the enhanced structure group used partially thickened CAs.ResultsFE model revealed that the enhanced structure improved the biomechanics during anterior retraction. Specifically, the second premolar, which had a smaller PDL area, experienced a smaller protraction force and moment, making it less likely to tip mesially. In the same vein, the molars could resist movement due to their larger PDL area even though they were applied larger forces. The resultant force of the posterior tooth was closer to the center of resistance, reducing the tipping moment. The canine was applied a larger retraction force and moment, resulting in sufficient retraction of anterior teeth. The experimental model demonstrated a similar trend in force variation as the FE model.ConclusionsEnhanced structure allowed force distribution more in accordance with optimal principles of biomechanics during the extraction space closure while permitting less mesial tipping and anchorage loss of posterior teeth and better retraction of anterior teeth. Thus, enhanced structure alleviated the roller coaster effect associated with extraction cases and offered a new possibility for anchorage reinforcement in clear aligner therapy.

Effectiveness of Anchorage Reinforcement using Skeletally Anchored Class II Elastics in Adolescent Patients

Effectiveness of Anchorage Reinforcement using Skeletally Anchored Class II Elastics in Adolescent Patients

Effect of Different Anchorage Reinforcement Methods on Long-Term Maxillary Whole Arch Distalization with Clear Aligner: A 4D Finite Element Study with Staging Simulation.

The objective of this study was to examine how various anchorage methods impact long-term maxillary whole arch distalization using clear aligners (CAs) through an automated staging simulation. Three different anchorage reinforcement methods, namely, Class II elastics, buccal temporary anchorage device (TAD), and palatal TAD, were designed. Orthodontic tooth movement induced by orthodontic forces was simulated using an iterative computation method. Additionally, the automatic adjustment of the CA was simulated through the application of the thermal expansion method. The results indicated that the palatal TAD group had the largest retraction of incisors, followed by the buccal TAD group and the Class II elastic group, while the least was in the control group. The largest distal displacements and efficiency of molar distalization for the first and the second molars were noticed in the palatal TAD group. Arch width increased at the molar and premolar levels in all groups. The FEM results suggested palatal TAD had the best performance considering anterior teeth anchorage maintenance, both sagittally and vertically. However, attention should be paid to the possible increasement of arch width.

Basalt fiber as natural reinforcement to improve the performance of ecological grouting slurry for the conservation of earthen sites

Abstract Grouting material is the core force transfer medium of grouting sealing and anchorage reinforcement methods for cracks in earthen sites; the performance of grouting slurry is the key to affecting the reinforcement effect. To solve the problems of poor flexural strength, easy shrinkage and cracking of existing grouting slurry, using Glutinous Rice Pulp, Calcined Ginger Nuts, and Loess Soil as substrates, and choosing the content and length of basalt fiber (BF) as control variables, 13 groups of specimens were designed by orthogonal test method to explore the influence of mixed fiber on the mobility, shrinkage, compressive, and flexural strength. The microstructure was analyzed by SEM to explain the strengthening mechanism from physical and chemical perspectives. The results show that the mobility decreases linearly with the increase in BF content and length; after mixing BF, the shrinkage rate is significantly reduced, but when the fiber length and content are relatively high, the surface is prone to cracking. The excellent bridging ability of BF can effectively improve the compressive and flexural strength of the specimen. When the fiber length and content are high, the specimen shows certain ductile failure characteristics, and the fracture energy increases more than 10 times.

Effective contribution ratio of the molar during sequential distalization using clear aligners and micro-implant anchorage: a finite element study

IntroductionThis study aims to investigate the biomechanical effects of anchorage reinforcement using clear aligners (CAs) with microimplants during molar distalization. And also explores potential clinical strategies for enhancing anchorage in the sequential distalization process.MethodsFinite element models were established to simulate the CAs, microimplants, upper dentition, periodontal ligament (PDL), and alveolar bone. In group set I, the 2nd molars underwent a distal movement of 0.25 mm in group set II, the 1st molars were distalized by 0.25 mm after the 2nd molars had been placed to a target position. Each group set consisted of three models: Model A served as the control model, Model B simulated the use of microimplants attached to the aligner through precision cuts, and Model C simulated the use of microimplants attached by buttons. Models B and C were subjected to a series of traction forces. We analyzed the effective contribution ratios of molar distalization, PDL hydrostatic stress, and von Mises stress of alveolar bone.ResultsThe distalization of the 2nd molars accounted for a mere 52.86% of the 0.25-mm step distance without any reinforcement of anchorage. The remaining percentage was attributed to the mesial movement of anchorage teeth and other undesired movements. Models B and C exhibited an increased effective contribution ratio of molar distalization and a decreased loss of anchorage. However, there was a slight increase in the undesired movement of molar tipping and rotation. In group set II, the 2nd molar displayed a phenomenon of mesial relapse due to the reciprocal force produced by the 1st molar distalization. Moreover, the efficacy of molar distalization in terms of contribution ratio was found to be positively correlated with the magnitude of force applied. In cases where stronger anchorage reinforcement is required, precision cuts is the superior method.ConclusionsThe utilization of microimplants in conjunction with CAs can facilitate the effective contribution ratio of molar distalization. However, it is important to note that complete elimination of anchorage loss is not achievable. To mitigate undesired movement, careful planning of anchorage preparation and overcorrection is recommended.

Headgear in orthodontics and dentofacial orthopedics

Extra oral appliances have been used since ages to bring about dental changes, skeletal changes and for anchorage reinforcement. Growth modifications can be done with help of these appliances. This can be done by inhibiting the growth or redirection of the growth. The biomechanics of the extraoral appliances needs to be understood well for using these appliances. The topic of headgear is vast and the following article tries to cover the details regarding the same in brief. The location of centre of resistance for application of force is important and plays a significant role in biomechanics and outcome of treatment results. Various types of headgears and their use depending on different criterias are discussed in detail.

Temporary Anchorage Devices.

Reaction to the force application is observed in the clinical scenarios as anchorage loss, which is the unwanted movement of the teeth. A plethora of approaches have been developed over time in orthodontics to overcome anchorage loss. These approaches are termed anchorage reinforcement procedures. Anchorage lossrefers to the unintended movement or shifting of teeth that are intended to remain stable and serve as anchoring points during orthodontic treatment. This loss of stability can occur in various dimensions, including horizontal, vertical, or transverse, and can result in undesired changes to the overall positioning and alignment of teeth. Anchorage can be termed as conventional intraoral anchorage which usually leads to significant anchorage loss. The conventional extraoral anchorage such as headgear suffers from the issue of compliance.

Three-dimensional morphologic analysis of the maxillary alveolar bone after anterior tooth retraction with temporary anchorage devices.

To investigate three-dimensional (3D) morphologic changes in the alveolar bone around the maxillary central incisors of patients who underwent premolar extraction and subsequent anterior tooth retraction using temporary anchorage devices (TADs). The subjects consisted of 16 patients with bimaxillary protrusion. The maxillary anterior teeth were retracted using sliding or loop mechanics and TADs for anchorage reinforcement. Cephalograms and computed tomography scans taken pretreatment and posttreatment were registered with respect to the palatal structures. The movement of the maxillary central incisors and morphologic changes in the anterior alveolar bone were evaluated quantitatively. Displacement in the palatal direction was observed in the alveolar bone around the incisors and the interdental septum. The displacement and bone remodeling/tooth movement ratio were larger on the labial side than the palatal side, and decreased progressively from the crest to apex level. The bone thickness was significantly increased on the labial side and decreased on the palatal side. Regional differences exist in morphologic changes of the alveolar bone during anterior tooth retraction using TADs. Attention should be paid to the crest region of the palatal alveolar bone because of its small original thickness and low remodeling activity.

EXPERIMENTAL STUDY ON THE STRUCTURAL PERFORMANCE OF RC SOFT-FIRST-STORY COLUMN-BEAM JOINTS WITH MECHANICAL ANCHORAGE OF COLUMN LONGITUDINAL REBAR

The present study describes the structural performance of a soft-first-story column-beam joint with mechanical anchorage of column longitudinal rebar. A new strengthening method using the anchorage reinforcement is presented to prevent brittle anchorage failure in this type of structure. A series of static loading tests was conducted using two scaled models representing the above column-beam joint to verify the effectiveness of the proposed strengthening. The test results clarified that the structural performance of the joint specimen was significantly improved by arranging the anchorage reinforcement.

EXPERIMENTAL STUDY ON STRUCTURAL PERFORMANCE OF RC L-SHAPED BEAM-COLUMN JOINTS USING MECHANICAL ANCHORS

This paper describes the effects of anchorage reinforcement for the structural performance of RC L-shaped beam-column joints using mechanical anchors at the ends of column longitudinal rebar. The requirements of the anchorage reinforcement are summarized referring to the previous study. Static loading tests of two specimens with and without the requirements of the anchorage reinforcement were conducted to verify its effectiveness; however, anchorage failure occurred at the ends of exterior column longitudinal rebar. Therefore, the requirements were modified based on the experimental damage, which was verified the effectiveness to completely prevent the occurrence of anchorage failure.

Bisphosphonates: how to proceed in orthodontics

Bisphosphonates are mainly used in the treatment of osteoporosis and in oncology. They bind to bone and inhibit the action of osteoclasts, leading to a decrease in bone remodeling and thus hindering tooth movement. The main objective was to present, through a review of the literature, the indications and therapeutic modalities for orthodontic treatment of patients who are or have been treated with bisphosphonates. The second objective was to propose a decisional organization chart for medical care. The search was done by keywords on PubMed. 189articles were found, mostly case reports. 1)Intravenous treatment is a contraindication to ODF treatment. 2)Per os treatment is possible with precautions: to be in accordance with the prescribing practitioner, avoid major travels, avoid surgical procedures (extractions...) which must be as atraumatic as possible. A delay in healing is to be expected. The benefit-risk ratio must be taken into account. The risks – the patient must be informed of them– are slowed movement and osteonecrosis. Clinical and radiological follow-up is necessary and may warrant re-evaluation of treatment at any time: excessive tooth mobility, molar furcation damage, unusually persistent periodontal pain and symptoms, fistulas, exposed areas of necrotic bone. The articles are of low grade. Most of the articles are studies made on animals. Research is ongoing to evaluate the value of bisphosphonates as anchorage reinforcement.

Effects of upper-molar distalization using clear aligners in combination with Class II elastics: a three-dimensional finite element analysis

IntroductionThe effects of upper-molar distalization using clear aligners in combination with Class II elastics for anchorage reinforcement have not been fully investigated yet. The objective of this study is to analyze the movement and stress of the whole dentition and further explore guidelines for the selection of traction methods.MethodsThree-dimensional (3D) finite element models are established to simulate the sequential molar distalization process, including the initial distalization of the 2nd molar (Set I) and the initial distalization of the 1st molar (Set II). Each group set features three models: a control model without Class II elastics (model A), Class II elastics attached to the tooth by buttons (model B), and Class II elastics attached to the aligner by precision cutting (model C). The 3D displacements, proclination angles, periodontal ligament (PDL) hydrostatic stress and alveolar bone von Mises stress in the anterior area are recorded.ResultsIn all of the models, the maxillary anterior teeth are labial and mesial proclined, whereas the distal moving molars exhibit distal buccal inclination with an extrusion tendency. With the combination of Class II elastics, the anchorage was effectively reinforced; model C demonstrates superior anchorage reinforcement with lower stress distribution in comparison with model B. The upper canines in model B present an extrusion tendency. Meanwhile, the mandibular dentition in models B and C experience undesired movement tendencies with little discrepancy from each other.ConclusionsClass II elastics are generally effective for anchorage reinforcement as the upper-molar distalization is performed with clear aligners. Class II elastics attached to an aligner by precision cutting is a superior alternative for maxillary anchorage control in cases that the proclination of upper incisors and extrusion of upper canines are unwanted.

Seismic performance of precast wide beam-column connections with asymmetrical anchorage reinforcement details

This study aims to investigate the seismic performances of precast concrete (PC) wide beam-column connections under reversed cyclic loading, in which the precast beam width is 1.5 times larger than that of column. Experimental program consists of a monolithic reinforced concrete (RC) specimen and two PC specimens with unique connection details. To avoid reinforcement congestions and also to secure emulative connecting performances, the PC specimens were integrated by asymmetrically placed connecting bars anchored into the column panel zone, and their anchorage end details were chosen as a key testing variable. Detailed numerical models were developed to identify the failure mechanisms and key influencing factors of the cyclic responses of PC wide beam-column connections. It appeared that the precast wide beam-column connections with asymmetrical anchorage details can also provide the so-called emulative seismic performance as a monolithic connection. Significant effects of bond-slip behaviors of the anchorage connecting reinforcements in the joint and axial compression level of the column on the seismic performance of PC wide beam-column connections were also identified by the nonlinear numerical simulations.

Comparison of the effectiveness of butterfly arch versus transpalatal arch in anchorage reinforcement: A linear 3D finite element study.

Background. Although there are various intraoral and extraoral appliances for anchorage management in orthodontics, most fail to preserve the anchorage efficiently. Thus, there is a need for an appliance that can preserve anchorage in the sagittal, vertical, and transverse directions with good patience compliance and cost-effectiveness. This study compared the efficacy of butterfly arch and transpalatal arch (TPA) as an anchorage reinforcing unit during orthodontic space closure using a linear finite element model. Methods. A 3D model of the maxilla and associated structures was developed from CT images of an individual's skull at a slice thickness of 1 mm. The magnitude of movements of anchor teeth in vertical, horizontal, and transverse directions was calculated in first premolar extraction cases during anterior retraction using a linear finite element model analysis and compared in two situations-butterfly arch and TPA attached to maxillary first molar for anchorage. Results. The anterior teeth had similar movements in the case of TPA and butterfly arch. There was more mesial and lingual movement in the first molars with TPA than in the butterfly arch, which had buccal but no mesial movement. The anterior teeth showed extrusion and the second premolars showed intrusion with TPA. Also, the von Mises stress and maximum principal stress were maximum with TPA at the cervical region of anterior and posterior teeth compared to the butterfly arch, where both stresses were uniformly distributed all over the teeth. Conclusion. A butterfly arch with its unique design, configuration, and biomechanical properties can be used as a device that can maintain the posterior anchorage efficiently.

A new perspective on the relationship between anchorage and palatal morphology: Three-dimensional digital model analysis.

The tooth movements were generally analyzed in two dimensions on cephalometric radiographs. Nowaday, 3D digital model analysis, which does not have any harmful effects on patients, can be used to evaluate the palatal morphology and coronal tooth movements in a very comfortable and easy way. To investigate the effect of palatal morphology on anchorage reinforcement during intraoral molar distalization with pendulum appliance using 3D model analysis. The material consisted of before (T0) and after (T1) dental plaster models of Class II malocclusion patients (17 females, 3 males) treated with pendulum appliance for molar distalization and Nance appliance for anchorage. T0 and T1 digital models were superimposed using the palatal area as a reference via three points and surface-matching software, and the changes in teeth movement were calculated for left and right central incisors, first premolars, and first and second molars. Palatal morphology was evaluated at T0 on digital models as palatal inclination, palatal depth angles, and anterior hard palate area. Wilcoxon test was used to evaluate the treatment results and Spearman's correlation analysis was performed to evaluate the relationship between palatal morphology and dental movement. The upper limit for the level of significance was taken as 0.05. Mesial movement of first premolars and distal movement of first and second molars were found to be statistically significant (P < 0.001). A weak negative correlation was found between the palatal inclination and the movement of first premolars (P < 0.045 and P < 0.003). Palatal depth angles and anterior hard palate area had no correlation with dental movements. Presented results supported that the mesial movement of premolar teeth decreased as the inclination of the palate increased.

Dentofacial asymmetry: non-surgical orthodontic treatment using extra-alveolar miniscrews

Asymmetric malocclusions have been always a challenge to orthodontists, with different dental, skeletal or dentoskeletal factors being probable causes for the condition. It is key to distinguish between dental and skeletal asymmetry before determining a predictable force system for corrective treatment. The use of mini-implants (MIs) to address anchorage needs in modern orthodontic practice has become an important tool for orthodontists. They have been widely used for anchorage reinforcement purposes and placed in the dentoalveolar region, especially between tooth roots (inter-radicular miniscrews). However, placement sites other than root areas allow more versatility of orthodontic movement since tooth roots do not interfere in tooth displacement, such as the extra-alveolar miniscrews.Objective The objective of the present paper is to present biomechanical concepts in which extra-alveolar mini-implants are placed in the infrazygomatic crest (IZC) and buccal shelf (BS) areas for correction of dento-facial asymmetries allowing predictable outcomes to be achieved with minimal need for patient's compliance and minor mechanic side effects.