Miniscrew Placement Research Articles

Dental Implants and Orthodontic Mini-Screws in a Patient with Undiagnosed Von Willebrand’s Disease: A Case Report

Dental Implants and Orthodontic Mini-Screws in a Patient with Undiagnosed Von Willebrand’s Disease: A Case Report

Distalization of mandibular molar with iatrogenic root fracture in Class III malocclusion: a case report

BackgroundPlacement of interradicular orthodontic miniscrews poses a potential risk of root damage, including superficial root contact and root fracture. This case report describes the iatrogenic root-injured tooth movement of a 27-year-old male with skeletal Class III malocclusion as nonsurgical orthodontic treatment.Case presentationAn orthodontic miniscrew between the mandibular right first and second molars perforated the distal root of the mandibular first molar. A root fracture was discovered 4 months after miniscrew placement. Owing to the potential risk of ankylosis related to surgical intervention, a direct orthodontic distalizing force was applied towards the fractured distal root segment without additional treatment, resulting in considerable movement of the fractured tooth with maintaining tooth vitality. However, gradual root resorption of a fractured tooth with a separate root segment was observed. The mandibular arch distalization of skeletal Class III malocclusion was successfully performed and retained for 3 years 8 months with stable occlusion.ConclusionsThis case reveals a clinical remedy when root movement of a tooth with root fracture is indicated. The use of extra-alveolar miniscrews or miniplates can be considered for mandibular arch distalization to prevent potential root injuries caused by miniscrew placement.Clinical trial numberNot applicable.

Patient's Perspective on Miniscrews During Orthodontic Treatment-A Systematic Review With Meta-Analysis.

During orthodontic treatment, undesirable reciprocal forces are generated during tooth movement, which explains the use of anchorage strategies to minimise their harmful effects through intra and/or extraoral appliances. Miniscrews are intraoral devices used for temporary skeletal anchorage. Miniscrews are small-sized intraoral devices used for temporary skeletal anchorage and are easy to place and remove. However, some studies refer to adverse effects such as inflammation, pain, and discomfort. This systematic review aims to synthesise the available evidence on the use of miniscrews during orthodontic treatment from the patient's perspective. The literature search was conducted using various databases MedLine through PubMed, Cochrane Library, Web of Science Core Collection, and EMBASE. A search was also carried out in the grey literature. The search terms used were "Orthodontic Anchorage Procedures," "mini-implant," "Mini Dental Implant," "Miniscrew," and "microimplant." Cochrane risk of bias tools was used to assess the quality of included studies. Patients tend to overestimate the pain inherent in this procedure. The insertion of micro implants is more accepted than the tooth extraction procedure, with less postoperative pain reported. The location, surgical technique, and type of anaesthesia used in the placement of miniscrews influence levels of discomfort. Additionally, the execution of a good surgical technique and the clinician's communication skills are factors that influence patient satisfaction and positive perception. The most frequent outcome reported is pain and discomfort, which varies depending on its location (less with mini interradicular screws than with extra-alveolar screws). Most patients are satisfied or very satisfied with this application.

Evaluating palatal mucosal thickness in orthodontic miniscrew sites using cone-beam computed tomography

PurposeTo comprehensively analyze the palatal thickness of soft tissues and determine optimal regions for the placement of palatal orthodontic miniscrews.MethodsCone-beam computed tomography (CBCT) images on the coronal plane were obtained from 60 patients (30 female, 30 male; age range 19–45; mean age 32 ± 11), with 3-mm intervals in the regions of the canine (Ca), first premolar (Pr1), second premolar (Pr2), midpoint between the first and second molars (M1-M2), first molar (M1), second molar (M2) and midpalate.ResultsThe mucosal thickness measurements between the teeth showed significantly greater thickness in the Ca region at the 3 mm point, in the Pr1 region at the 6 mm point, and in the Pr2 region at the 9 and 12 mm points. At the 9 mm point, the Pr1 region demonstrated greater thickness than the M1-M2 whereas the Pr2 region was thicker than the M1 and M1-M2 regions. At the 12 and 15 mm points, the thickness increased from anterior to posterior: the Pr1 region was thinner than the Pr2, M1, and M2 regions and the Pr2 region was thinner than the M2 region. A schematization was devised for the optimal areas recommended for miniscrews in the palatal region.ConclusionThe mucosal thickness in the palatal region increases from anterior to posterior except the midpalatal region. Based on the results, in terms of soft tissue, the most suitable place for miniscrew placement is 6 mm from the gingival margin of the teeth and in the median portion of the palate. The findings may guide clinicians in choosing the optimal sites for palatal mini-implants.

Homemade CAD-CAM surgical guide for palatal mini-screw insertion for maxillary molar distalization providing anchorage. A two times original protocol

Temporary Anchorage Devices have revolutionized our approach to anchorage management. However, their placement may carry risks, such as root perforation, damage to the periodontal ligament, buccal-nasal communication, etc. The aim of this article is to describe an original protocol in two times for the placement of a palatal mini-screw through guided surgery using a guide created by Computer-Aided Design and Manufacturing (CAD/CAM) followed by the transfer of placement information to the laboratory for the fabrication of a Custom Medical Device (CMD) for distalization. A two-stage protocol is described and illustrated step by step. Phase 1 comprises 7 steps (including superimposition of maxillary cast and profile teleradiography, surgical tray design), followed by phase 2, which involves 3 final steps (including production of impression for laboratory, production of laboratory model with transfer of mini-screw position). Although the position of the mini screws remains precise, a discrepancy between the planning and the intraoral situation exists. The addition of a second step therefore enables the distalization appliance to be fitted precisely and without pitfalls. Finally, this protocol ensures safe placement, making work easier for the practitioner and, ultimately, for the patient. In a two-stage process, the placement of palatal mini screws through guided surgery using a guide created by CAD/CAM followed by the transfer of this information to the laboratory for the fabrication of a CMD for distalization proves to be a relevant approach.

To evaluate the effectiveness of biting on chewie as pain management during debonding: A cross-sectional study

: During orthodontic treatment, pain and discomfort are frequently felt by patients during procedures like separator placement, archwire placement, orthodontic force application, miniscrew placement and debonding. The purpose of this study is to look into the effects of biting on Chewie for pain management during debonding procedure. Out of sample size of 128 sites, 64 sites (right or left) was assigned as Chewie and 64 sites as control group and debonding was carried out. Pain was evaluated on VAS scale from 1 to 10. Chewie group has a mean value of 1.76, with a 95% confidence interval ranging from 1.59 (Lower) to 1.93 (Upper). Conventional group has a mean value of 2.00, with a 95% confidence interval ranging from 1.79 (Lower) to 2.20 (Upper). : Debonding performed with gently squeezing action and biting on the chewie will be sufficient to keep pain to a minimum level and no other additional pain-relief method will be required.

Anatomical Bone Characteristics of the Buccal Step Insertion Site for Mini-Screw Placement in Orthodontic Treatment: A CBCT Study

Background: To analyze the anatomical characteristics of a posterior area in the mandible localized distally to the second molars and extending in the vestibular direction toward the bony step, which we define as “buccal step”, in a patient with different skeletal patterns for mini-screw insertion. Methods: The sample included 85 CBCT (cone beam computed tomography) records selected from the digital archive. Analysis focused on the buccal step area. Sections were obtained in axial view using reference lines, and measurements of cortical and total bone were taken at specific points M0 (starting point, 6 mm apical from CEJc—cementoenamel junction crest), M2 (located 2 mm posterior to M0 in the apical direction), and M4 (positioned 4 mm posterior to M0 in the apical direction) in both directions. Six measurements were recorded for each scan root plane, assessing cortical and total bone depth. Results: The thickness of the bone increases toward the inside of the mouth at all tested sites (M0, M2, M4), which is good for placing mini-screws. Cortical bone thickness decreases toward the inside of the mouth, with no significant differences among the sites except for M0 vs. M4. People with a particular jaw shape (hypo-divergent) have a thicker cortical bone, indicating that facial structure affects bone thickness. Conclusions: The posterior buccal step insertion site has biomechanical advantages and reduces the risk of damaging roots during mini-screw insertions.

Contributions of Alveolar Bone Density and Habitual Chewing Side to the Unilateral Failure of Orthodontic Mini-Screws: A Cross-Sectional Study

This study aimed to analyze the relationship between bone density, habitual chewing side (HCS), and mini-screw stability to investigate the intra-individual factors contributing to mini-screw failure. This retrospective study included 86 sides in 43 adults, who underwent bilateral maxillary mini-screw placement with subsequent unilateral failure of the mini-screw. Pre-treatment cone-beam computed tomography was used to measure the buccal cortical bone thickness and bone density on the failed and successful sides. Pre-treatment mandibular kinesiographic records were used to determine the HCS. Paired t-tests, one-proportion z-tests, and multivariable multilevel Poisson regression were used to examine the statistical significance. The buccal cortical bone thicknesses were 0.93 ± 0.27 mm (unsuccessful side) and 1.01 ± 0.27 mm (successful side), with no significant difference. The bone density on the unsuccessful side (1059.64 ± 202.64 mg/cm3) was significantly lower than the success side (1317.89 ± 332.23 mg/cm3). Regarding HCS, 27.9% of failures occurred on the preferred side, and 62.8% occurred on the non-preferred side. After adjusting for all factors, the non-preferred side showed a 2.22 times higher prevalence ratio for mini-screw failure than the preferred side. HCS is significantly related to mini-screw stability, while the cortical bone thickness, bone density, and site of mini-screw implantation were not correlated.

Site selection of micro-implant anchorages in the infrazygomatic crest in adult orthodontic patients.

To determine the optimal placement of miniscrews, this study compared adult male and female patients in terms of cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest region. The cone beam computed tomography imaging data of 200 patients (20-30 years old; 100 males and 100 females) were collected. The right maxillary posterior teeth in the sagittal plane were divided into six levels from proximal to distal, and three measurement sites were positioned at vertical distances of 8, 10, and 12 mm from the cementum. Cortical bone density, cortical bone thickness, and available bone width were measured in 18 measurement sites in the infrazygomatic crest and analyzed statistically. The highest cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest in adult male and female patients were at the level of the interradicular space between the maxillary second premolar and maxillary first molar. The bone cortical density and thickness increased with vertical height, whereas the available bone width decreased with increasing vertical height. Differences were observed in cortical bone density, cortical bone thickness, and available bone width between adult male and female patients. The optimal implantation sites of the micro-implant anchorages in the infrazygomatic crest were at the level of the interradicular space between the maxillary second premolar and the maxillary first molar, and the vertical height of the optimal implantation site in males was appropriately higher than that in females.

Analysis of Stress Distribution and Displacement Based on the Miniscrew Positions of the Palatal Slope Bone-borne Expander: A Finite Element Study.

This study aimed to investigate the stress distribution pattern of the palatal slope bone-borne expander on the maxillary area according to a different anteroposterior position of anchored miniscrews using finite element analysis. Nasomaxillary stereolithography files with three different anteroposterior anchored miniscrew positions of the palatal slope bone-borne expander were determined as model A, B, and C. Each model consists of four supported miniscrews. Model A: two anterior miniscrews were located between the maxillary canine and the first premolar, and two posteriors between the second premolar and the first molar. Model B: two anteriors were between the lateral incisor and the canine, and two posteriors were the same as in model A. Model C: two anteriors were the same as in model A, and two posteriors were distal to the first molar. One turn of expander screws was applied. Maximum principal stress, equivalent elastic strain, equivalent von Mises stress, and transverse displacement were evaluated. The maximum principal stress was mostly found at the bone-miniscrew interface. Model A exhibited an intersecting area of stress between the supported miniscrews. The highest value of principal stress was in model B, while model C showed a uniform distribution pattern. The elastic strain pattern was similar to the principal stress in all models. The highest value of equivalent von Mises stress was located on the expander screw. The largest amount of transverse displacement of teeth was in model A, while model C exhibited a more consistent transverse displacement than other models. Vertical displacement of posterior teeth was also noticed. Based on the result, it revealed that the various anteroposterior miniscrew placements of the palatal slope bone-borne expander had various patterns of stress distribution and resulted in various outcomes. It may be inferred that model A's miniscrew location was advantageous for obtaining expansion quantities, but model C's miniscrew position was advantageous for maintaining consistent biomechanics.

The impact of immediate versus delayed mini-screw placement on alveolar bone preservation and bone density following tooth extraction: evidence from a canine model

The aim of this study was to evaluate the impact of mini-screw placement on the alveolar ridge using a split-mouth design. Twelve beagles underwent bilateral extraction of their lateral teeth. In the immediate group, a mini-screw was unilaterally placed approximately 3–4 mm below the alveolar crest of the extraction site on the experimental side. The delayed group received mini-screws six weeks after tooth extraction. On average, the dogs were sacrificed after 11 weeks, and the maxillary bones were excised and scanned using cone-beam computed tomography (CBCT). Histopathological examinations were conducted to assess inflammation and bone formation scores. The results showed that in the immediate group, bone height was significantly greater on the intervention side compared to the control side (p < 0.05), whereas there was no significant difference in the delayed group. In both groups, there was a significant increase in bone density around the mini-screws compared to the control sides (p < 0.05). Mini-screw insertion led to a significant enhancement of bone growth in both groups (p < 0.05), with no notable differences between the two groups. The mini-screws did not have any impact on bone inflammation or width. Overall, both immediate and delayed mini-screw placement in the extraction socket positively influenced bone dimensions, density, and histological properties. However, immediate insertion was more effective than delayed placement in preserving vertical bone height, despite delayed insertion resulting in higher bone density.

Assessment of mandibular cortical bone thickness for miniscrew placement in relation to the vertical facial patterns using CBCT: A cross-sectional Study

Introduction: The need of more anchorage in the orthodontic daily practice has introduced the use of temporary anchorage devices (TADs). Cortical bone thickness has been one of the major factors on the success rate of the stability of TADs. Different vertical dimension patterns can be found among orthodontic patients with potentially variable cortical bone thickness. Aim of the study: to assess the cortical bone thickness in the posterior region of the mandible in relation to different vertical facial patterns using Cone-beam computed tomography (CBCT) and to evaluate the progressive change in the thickness of cortical bone from 4,6 to 8 mm from the crest of the alveolar bone toward the apical region. Methods: Thirty-six participants were selected and their cephalometric x-rays and CBCTs were analyzed and compared. Vertical facial pattern was measured with the use of the mandibular plane angle and participants were grouped in 3 categories according to the measures. On the CBCTs, buccal and lingual cortical bone thickness were measured from 4,6 and 8 mm from the alveolar crestal bone and compared. All analyses were conducted using IBM SPSS Statistics for Windows, v.26 (IBM Corp., Armonk, NY, USA). The significance level was set at α = 0.05 for all statistical analyses. Results: There was no statistically significant differences were observed between the vertical dimensions groups in terms of buccal and lingual measurements at 4, 6, and 8 mm from cemento-enamel junction (CEJ) between 44/45, 45/46, and 46/47 (P&gt;0.05). Conclusions: There was a progressive increase in cortical bone thickness in most of the studied groups from the alveolar crest to the apical region.

Comparison between two types of grids for placement of mini-screw implant in posterior maxillary segment

Use of mini-screw implants is in vogue. It has brought about a drastic change in day to day practise for orthodontists. Despite being the most popular source of anchorage, it is not easy for newer clinicians to perfectly figure out the site of implant placement and the accuracy by which it should be placed to avoid failure. A customised grid or mesh is the simplest way to gain assistance for placement of miniscrew implants. This article focuses on comparison of two types of grids for placement of implant accurately and to guide the clinician in such a way that minimises all the possible errors.

Should Cone-Beam Computed Tomography Be Performed Prior to Orthodontic Miniscrew Placement in the Infrazygomatic Crest Area?-A Systematic Review.

There is no unequivocal scientific consensus for the temporary anchorage device (TAD) positioning in the infrazygomatic crest area (IZC). The two principal aims of this systematic review were to assess bone availability in the IZC and to establish both the target site and the need for cone-beam computed tomography (CBCT) prior to miniscrew placement. The study was performed following PRISMA guidelines (PROSPERO: CRD42023411650). The inclusion criteria were: at least 10 patients, three-dimensional radiological examination, and IZC assessment for the TAD placement. ROBINS-I tool and Newcastle-Ottawa Scale were used for quality evaluation. No funding was obtained. The study was based on the information coming from: PubMed, Google Scholar, Web of Science Core Collection, MDPI, Wiley, and Cochrane Libraries. The last search was carried out on 1 August 2023. Fourteen studies were identified for analysis. A narrative synthesis was performed to synthesize the findings of the different studies. Unfortunately, it is not possible to establish the generally recommended target site for IZC TAD placement. The reasons for this are the following: heterogeneity of available studies, inconsistent results, and significant risk of bias. The high variability of bone measurements and the lack of reliable predictors of bone availability justify the use of CBCT for TAD trajectory planning. There is a need for more high-quality studies aiming three-dimensional bone analysis of the IZC.

Computed Tomographic Evaluation of Buccal Shelf Dimensions in South Indian Patients With Sagittal Skeletal Class III Malocclusion: A Retrospective Study.

Background Computed tomographic evaluation of mandibular buccal shelf region in skeletal class III malocclusion cone beam computed tomography (CBCT) studies have been reported to have great alteration in the thickness of mandibular buccal shelf region owing to the different growth patterns and ethnic variations. The aim of this study was to determine the total and cortical bone thicknessin the mandibularbuccal shelf(MBS) region for extra-alveolar mini-screw placement in South Indian patients with sagittal skeletal class III malocclusion. Material and methods This retrospective computed tomographic study consisted of archived files of the Dravidian population with class III skeletal base that met the eligibility criteria. The total bone and cortical bone thickness of the buccal shelf regions were evaluated in relation to three anatomical sites at various depths and angulations. One-way ANOVA and Tukey honestly significant difference (HSD) post hoc tests were used for statistical analysis. Pearson correlation coefficient was performed to compare if any relation existed between bone thickness and the growth pattern. Results The maximum bone thickness in the buccal shelf region in our study was found at the distal portion of the second molar root, 8-12 mm from its cementoenamel junction (CEJ) and at 30-45 ° angulation (p-value<0.005). There was a positive correlation between the hypo-divergent growth pattern and the thickness of the bone. Conclusion Based on the sites recorded, the preferred site for mini screw placement in Class III patients is the distobuccal cusp region with respect to the second molarat a depth of 8-12 mmand at angulation of 30-45 °. There was a moderate correlation with hypo-divergent growth patterns, suggestive of a wider and thicker mandibular buccal shelf region in these subjects.

Clinical Experience and Digital Knowledge in Virtual Planning of Palatal Orthodontic Miniscrew Insertion

At present, temporary anchorage devices (TADs) are continuously gaining importance because of their usability and their possibility to broaden clinical force applications; however, how difficult can their placement planning be? Aim: The aim is to evaluate the association between clinical experience, digital knowledge and the capability of virtual planning in palatal orthodontic miniscrew insertion in various types of clinicians, divided by different levels of experience. Methods: A total of 30 participants (10 dental students, 10 orthodontics students and 10 orthodontists) with different levels of clinical and digital experience were randomly recruited in this cross-sectional study. All participants performed a pre-test survey followed by two consecutive digital planning tests and, finally a post-test survey. The digital planning test was made using software BlueSkyBio-BlueSkyPlan, a surgical guide module. The differences in terms of planning execution time, miniscrew insertion and surgical guide realization were evaluated. The Kruskal–Wallis and Mann–Whitney U-tests were performed to determine the effects of independent variables and interactions between groups. Results: The relation between clinical experience and bicorticalism was statistically significant (p = 0.017); in the planning execution time, a significant difference was evident between the dental students and the orthodontics students (T1: p = 0.015 and T2: p = 0.019), who, having good digital knowledge, took an average of 4.58 min less in T1 (p = 0.025), while this difference was significantly reduced in T2 (p = 0.106). Conclusion: Clinical experience increased miniscrew placement accuracy and digital knowledge reduced execution planning time but both had a stronger impact in the first test than in the second.

Effects of an augmented reality aided system on the placement precision of orthodontic miniscrews: A pilot study

Background/purposeAugmented reality (AR) is gaining popularity in medical applications, which may aid clinicians in achieving improved clinical outcomes. The purpose of this study was to determine the positional and angle errors of orthodontic miniscrew placement by using a self-developed AR aided system. Materials and methodsCone beam computed tomography (CBCT) and patient printed models were used in in vitro experiments. The participants were divided into a control group and an AR group, in which traditional orthodontic methods and the AR-aided system were used respectively. After the information obtained from the CBCT images and navigation system was combined on the display device, the AR-aided system indicated the planned miniscrew position to guide the clinicians during the placement of miniscrews. Both methods were compared by a senior and a junior dentist, and the position and angle of miniscrew placement were statistically analyzed using Wilcoxon's signed-rank and Mann–Whitney U tests. ResultsWhen the AR-aided system was used, the accuracy of miniscrew placement in the mesiodistal position considerably increased (83%) when the procedure was performed by a senior clinician. In addition, the accuracy of miniscrew placement in the mesiodistal position and the angle of miniscrew placement considerably increased by approximately 67% and 72%, respectively, when the procedure was performed by a junior clinician. The position error of miniscrew placement was smaller for the junior clinician when the AR-aided system was used than for the senior clinician. ConclusionThe AR-aided system improved the accuracy of miniscrew placement regardless of the clinician's level of experience.

Do the miniscrews of the prefabricated systems for the “appliance first” protocol of miniscrew-assisted rapid palatal expansion have lengths that meet the palatal thickness of patients?

In the "appliance first" protocol of miniscrew-assisted rapid palatal expansion, the prefabricated shape of the expanders limits the potential locations for miniscrew placement. Considering the influence of palatal thickness on the selection of the optimal length of miniscrews, this study aimed to evaluate the thickness of both bone and mucosa of the palate of patients aged 6-65 years and suggest optimal lengths of miniscrews for this approach. Two hundred and eighty-two cone-beam computed tomography of patients of both sexes were divided into 3 groups according to age. The thicknesses of bone and mucosa were measured in the anterior and posterior regions of the palate. Males showed a greater thickness of palatal bone than females. The thickness of both bone and mucosa was greater in the anterior region of the palate. The young patients showed greater bone thickness than adults and mature adults. The mature adults showed thinner bone thickness in the posterior region of the palate and greater mucosal thickness along the palate than young patients and adults. Development of miniscrews with longer thread lengths is necessary. Miniscrews with a 3-mm thread length would prevent excessive extravasation in the posterior region of the palate. The thickness of both bone and mucosa of the palate is variable and influenced by sex and age. Manufacturing additional miniscrews with different lengths of thread is suggested to achieve bicortical anchorage in patients undergoing the "appliance first" protocol of miniscrew-assisted rapid palatal expansion.

Matrix Metalloproteinase-8 Levels in Peri-Miniscrew Crevicular Fluid During Immediate and Delayed Orthodontic Loading--A Split-Mouth Study.

Purpose: To compare the matrix metalloproteinase-8 (MMP-8) levels in the peri-miniscrew implant crevicular fluid (PMCF) of immediate-loaded and delayed-loaded miniscrew implants at different time intervals. Materials and Methods: Titanium orthodontic miniscrews were placed bilaterally in the attached gingiva of 15 patients between the maxillary second premolar and maxillary first molar for en masse retraction. This split-mouth study was designed to have an immediate-loaded miniscrew on one side and a delayed-loaded miniscrew on the other side that was loaded 8 days after miniscrew placement. PMCF was collected from the mesiobuccal aspects of the immediate-loaded implants at 24 hours, 8 days, and 28 days after loading, and from the delayed-loaded miniscrew implants at 24 hours and 8 days before loading and 24 hours and 28 days after loading. An enzyme-linked immunosorbent assay kit was used to assess MMP-8 levels in the PMCF samples. Unpaired t test, ANOVA F-test, and Tukey post hoc test were used to evaluate data at the P < .05 level. Results: Although there were slight alterations in the MMP-8 levels in the PMCF over time, there was no statistically significant difference in the MMP-8 levels between groups. There was a statistically significant decrease in the levels of MMP-8 between 24 hours after miniscrew placement and 28 days after loading on the delayed-loaded side (P < .05). Conclusion: The MMP-8 levels did not vary much between immediate-loaded and delayed-loaded miniscrew implants as a result of the force application. However, there was no significant difference between immediate loading and delayed loading in terms of biologic response to mechanical stress. The increase in MMP-8 levels after 24 hours post-miniscrew insertion, as well as the subsequent gradual reduction over the course of the study period in both immediate and delayed groups after loading, is probably due to the bone adapting to stimuli.

Finite Element Analysis of Maxillary Teeth Movement with Time during En Masse Retraction Using Orthodontic Mini-Screw

Introduction: The aim of this study was to determine the placement of an orthodontic mini-screw (OMS) and the length of an anterior retraction hook (ARH) with en masse retraction. Continuous maxillary tooth movement pattern was simulated by finite element analysis (FEA). Materials and methods: Extraction of the first premolar was hypothesized with a finite element model. The placement of OMS was analyzed for the following two groups: (1) a high OMS (HOMS) group with OMS placed horizontally at the mesial side of the second premolar and apically 10 mm above the arch wire, and (2) a low OMS (LOMS) group with OMS placed horizontally between the second premolar and the first molar and apically 8 mm above the arch wire. According to the height of ARH, each group was divided into three subgroups. Results: When the extraction space of the first premolar was closed, anterior teeth were intruded in the HOMS group but extruded in the LOMS group. In all cases, the first molar was intruded. According to the intrusion of the first molar and extrusion of anterior teeth, the occlusal plane rotated clockwise (CW) in the LOMS group. However, in the HOMS1 group, the occlusal plane rotated counterclockwise (CCW) due to more intrusion of anterior teeth than that of the first molar. Conclusion: By analyzing six cases of different OMS and ARH, changes of incisor and molar in en masse retraction with the extraction of the first premolar could be predicted. In addition, OMS placement and ARH length can be determined based on results of incisal showing. This study can also help esthetic orthodontic results.