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OBJECTIVES: To evaluate anchorage loss after en masse retraction in bimaxillary dentoalveolar protrusion patients using friction vs frictionless mechanics. MATERIALS AND METHODS: Thirty patients with bimaxillary dentoalveolar protrusion needing extraction of upper first premolars and en masse retraction with maximum anchorage were included in this two-arm, parallel, single-center, single-blinded randomized clinical trial with a 1:1 allocation ratio using fully sealed opaque envelopes. Friction group retraction utilized elastomeric power chain between miniscrews and hooks crimped mesial to upper canines on 17 × 25 stainless steel archwire. Frictionless group used customized T-loop springs loading upper first molars indirectly anchored to miniscrews. Activation was every 4 weeks until full retraction. The primary outcome assessed was anchorage loss evaluated at cusp tip and root apex of the first molar. First molar rotation, incisor tip and torque, and root resorption of anterior teeth were evaluated on digital models and cone beam computed tomography taken before and after space closure. RESULTS: Anchorage loss at crown of first molar was significantly more in frictionless group by 2.1 mm (95% CI = -0.4 to 3.5), (P = .014), while there was no significant difference in anchorage loss at root apex between groups. Significant mesial in molar rotation of 6.672° (95% CI = 12.2-21.2), (P = 0.02) was greater in the frictionless group. Both groups showed comparable tip, torque, and root resorption values. No severe harms were reported. There was mild gingival overgrowth and inflammation in the frictionless group due to T-loop irritation. CONCLUSIONS: Extra anchorage considerations are needed during en masse retraction when frictionless mechanics is implemented as higher anchorage loss and molar rotation were detected. No difference in tip, torque, and root resorption was observed.

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BACKGROUND: Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome. OBJECTIVE: To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion. TRIAL DESIGN: Two-arm parallel group, single-center randomized clinical trial. MATERIALS AND METHODS: Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure. BLINDING: The outcome assessor was blinded through data concealment during assessment. RESULTS: Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ±â€…0.66 mm/month in the frictionless group compared to 0.72 ±â€…0.36 mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ±â€…0.72 mm in the friction group compared to 1.29 ±â€…0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference. HARM: one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash. LIMITATION: The study focused only on the maxillary arch. CONCLUSION: Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant. TRIAL REGISTRATION: Clinicaltrials.gov with the identifier NCT03261024.

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INTRODUCTION: The study aimed to determine the influence of palatal injection of platelet-rich plasma (PRP) on the rate and type of orthodontic tooth movement (OTM) during the en-masse retraction of upper anterior teeth. MATERIALS AND METHODS: Two-arm parallel-group trial, in which 30 class II division 1 adult patients (7 males and 23 females) aged 16 to 27 years were recruited. The sample was randomly divided into two groups: the experimental group, in which PRP was injected in the palatal mucosa of the maxillary six anterior teeth immediately before starting the en-masse retraction of upper anterior teeth, whereas in the control group, traditional treatment was employed. Following the first premolar extraction, space closure was accomplished using frictionless mechanics for the en-masse retraction of upper anterior teeth. In both groups, a rigid segmented arch made of stainless steel with a diameter of 0.021 x 0.025 inch and an 8-mm power arm was used for the upper anterior teeth, and mini-implants were inserted between the upper second premolar and first molar at 8 mm apical from the archwire line. NiTi coil springs were used for retraction. Measurements were recorded at the onset of space closure (T0) and every 40 days till the middle of the en-masse retraction of upper anterior teeth (T1). RESULTS: Thirty patients completed the trial, and no patients were lost to follow-up in both groups. The OTM rate in the PRP group was similar to that of the control group (P = 0.596). The upper anterior teeth in the two groups were retracted mostly by controlled tipping and partially by translation. Statistically insignificant differences were observed between the two groups regarding the rest of the cephalometric variables. No serious harms were observed in either group. CONCLUSIONS: PRP was ineffective in accelerating the OTM rate during the en-masse retraction of upper anterior teeth and it did not affect the type of tooth movement.

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OBJECTIVE: To evaluate and compare the displacement pattern of maxillary anterior teeth in the sagittal and vertical planes and evaluate the stress distribution in pdl, bone, teeth of the maxillary anterior region, and around the mini-implants during simultaneous en-masse retraction and intrusion using two, three, and four mini-implants combinations. METHODS: A three-dimensional FEM model of maxillary teeth and periodontal ligament housed in the alveolar bone with extracted first premolarswasgenerated. The models were broadly divided into three groups according to the number of mini-implants. Mini-implants were placed bilaterally between the second premolar and molar in group I, and along with bilateral implants, an additional mid-implant was placed between the central incisors as in group II, whereas in group III, anterior mini-implants were placed in between lateral incisors and canine bilaterally. RESULTS: The two mini-implant model showed the maximum amount of retraction in the sagittal plane followed by three and four mini-implant models. In the vertical plane, all six anterior teeth showed intrusion only in the four mini-implant model. The stress in cortical bone, cancellous bone, PDL, around the mini-implants, and in lateral incisor was maximum in the three mini-implant model, followed by four mini-implants with the least stress in the two mini-implant model. CONCLUSION: The four mini-implant model is better than the three and two mini-implants model as there is a more even distribution of force in the four mini-implants model as compared to the three mini-implants model.

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BACKGROUND: Low-intensity electrical stimulation (LIES) is considered a relatively recent technology that has received little attention in orthodontics as a method of acceleration. This study aimed to evaluate patient-reported outcome measures when LIES is used to accelerate the en-masse retraction of the upper anterior teeth. MATERIALS AND METHODS: The sample consisted of 40 patients (8 males, 32 females; mean age 21.1 ± 2.3 years), with Class II division I malocclusion who required extraction of the first premolars to retract upper anterior teeth. They were randomly assigned to the LIES group (n = 20) and the conventional en-masse retraction group (CER; n = 20). Patient responses regarding pain, discomfort, burning sensation, swelling, chewing difficulty, speech difficulty, and painkillers' consumption were recorded at these nine assessment times: 24 h (T1), 3 days (T2), and 7 days (T3) after force application, then in the second month after 24 h (T4), 3 days (T5), and 7 days (T6) of force re-activation, and finally after 24 h (T7), 3 days (T8), and 7 days (T9) of force re-activation in the third month. RESULTS: The mean values of pain perception were smaller in the LIES group than those in the CER group at all assessment times with no statistically significant differences between the two groups except during the second and third months (T5, T6, T8, and T9; P < 0.005). However, discomfort mean values were greater in the LIES group with significant differences compared to CER group during the first week of the follow-up only (T1, T2, and T3; P < 0.005). Burning sensation levels were very mild in the LIES group, with significant differences between the two groups at T1 and T2 only (P < 0.001). Speech difficulty was significantly greater in the LIES group compared to CER group at all studied times (P < 0.001). High levels of satisfaction and acceptance were reported in both groups, without any significant difference. CONCLUSION: Both the LIES-based acceleration of en-masse retraction of upper anterior teeth and the conventional retraction were accompanied by mild to moderate pain, discomfort, and chewing difficulty on the first day of retraction. These sensations gradually decreased and almost disappeared over a week after force application or re-activation. TRIAL REGISTRATION: ClinicalTrials.gov, ClinicalTrials.gov, NCT05920525. Registered 17 June 2023 - retrospectively registered, http://clinicaltrials.gov/study/NCT05920525?term=NCT05920525&rank=1 .

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Excessive orthodontic force can induce inflammatory tooth root resorption due to sustained high stresses within the periodontal ligament (PDL). This study aimed to analyze the PDL pressures during upper incisor retraction using the en masse method with TISAD. The finite element method (FEM) ensured consistent conditions across cases. The models included bone geometry, adjacent teeth, PDL, and orthodontic hardware, analyzed with LS-Dyna. The pressure ranged from 0.37 to 2.5 kPa across the dental arch, with the central incisors bearing 55% of the load. The pressure distribution remained consistent regardless of the force or hook height. The critical pressure (4.7 kPa) was exceeded at 600-650 g force, with notable pressure (3.88 kPa) on the palatal root wall of the right central incisor. Utilizing 0.017 × 0.025 SS archwires in MBT 0.018 brackets provided good torque control and reduced the root resorption risk when forces of 180-200 g per side were applied, maintaining light to moderate stress. Triple forces may initiate resorption, highlighting the importance of nonlinear finite element analysis (FEA) for accurate oral cavity simulations.

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OBJECTIVES: This finite element study aimed to simulate maxillary canine movement during anterior teeth retraction. MATERIALS AND METHODS: Three methods of maxillary canine movement including miniscrew sliding with high hooks (MSH), miniscrew sliding with low hooks (MSL), and the traditional sliding method (TS) without using miniscrews were simulated using three-dimensional finite element analysis. The initial displacement of the maxillary canine, the maximum principal stress of the periodontal ligament and the Von Mises stress were calculated. RESULTS: The distolingual tipping movements of the canine were shown in three movement modes. MSH showed a small tendency to lingual tipping movement and a extrusion movement while MSL had the largest lingual inclination. TS demonstrated a tendency toward distolingual torsion displacement. Compressive stress values were mainly concentrated in the range - 0.003 to -0.006 MPa. For tensile stress, the distribution of MSH and MSL was concentrated in the range 0.005 to 0.009 MPa, TS was mainly distributed about 0.003 MPa. Von Mises equivalent stress distribution showed no significant difference. CONCLUSIONS: The loss of tooth torque was inevitable, irrespective of which method was used to close the extraction space. However, miniscrew application and higher hooks reduced the loss of torque and avoided lingual rotation. CLINICAL RELEVANCE: This study shows that miniscrew implants with different hooks can better control the movement of the maxillary canines. The non-invasive nature of the finite element analysis and its good simulation of dental stress and instantaneous motion trend have a clinical advantage in the analysis of tooth movement.

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(1) Background: This study aimed to compare patient-reported outcome measures when accelerating en masse retraction between the piezocision procedure and the subsequent application of low-level laser therapy (FC+LLLT), with the piezocision alone (FC), and in a control group. (2) Methods: A three-arm randomized controlled trial (RCT) was conducted involving 60 patients (41 females and 19 males) with Class II division I malocclusion. The en masse retraction was performed using NiTi closed coil springs attached to miniscrews. The LLLT was performed using an 808 nm Ga-Al-As diode laser. Patient responses regarding pain, discomfort, swelling, and chewing difficulties were reported at ten assessment points. (3) Results: The greatest pain levels were observed 24 h after the application of force during the first and third months of retraction. The mean pain, discomfort, swelling, and chewing difficulties were significantly smaller in the control group than in the FC and FC+LLLT groups. High satisfaction levels were reported in all three groups (p < 0.05). (4) Conclusions: The accelerated en masse retraction via piezocision, followed by a small course of LLLT, was accompanied by significantly fewer pain, discomfort, and chewing difficulties than the control group. LLLT is a valuable addition to piezocision, with an improved patient experience.

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This article reviews and critically analyzes the literature on mini-implants (temporary anchorage devices) for anterior en masse retraction in orthodontics. The search methods used were an E-database search, a secondary computerized search of orthodontics journals, and a reference list of selected studies. Eligibility criteria included individuals who underwent orthodontic treatment for correction of malocclusion with premolar extraction. Data were taken from PubMed and Scopus as well as the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews. Keywords used for searching the article were temporary anchorage devices, premolar extraction, orthodontics, and anterior en masse retraction, Anterior en masse retraction with sliding mechanics in pre-adjusted edgewise appliances was considered for the study. Data collection and analysis involved three different researchers performing three steps of selection. All titles were initially filtered for irrelevant review articles. In the first step, all summaries from the selected studies were reviewed, and in the second, the entire content of the papers was read. The study was then discarded based on qualifying standards. A chart was created using the data from the final chosen research as well as the findings. The following information was evaluated for the final table: author, publication year, research structure, study group, sample size, methods/measures, study findings, and conclusion about frictionless mechanics. Results showed that a meta-analysis was not feasible due to clinical and statistical variability, as well as variations in study design, sample selection, and sample size. Thus, it was concluded that sliding mechanisms are widely employed in orthodontic treatment, but temporary anchorage devices and sliding mechanisms deliver great results. There is a need to raise awareness about these devices and use them with care.

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OBJECTIVE: This study aimed to assess the levels of pain, discomfort, and functional impairment associated with the en-masse retraction of the upper anterior teeth when treating Class II division 1 malocclusion patients using traditional corticotomy or flapless corticotomy. In addition, an assessment of patients' satisfaction with the selected surgical intervention was undertaken at one-month post-operatively. MATERIALS AND METHODS: The study sample comprised 40 patients with Class II division 1 malocclusion, randomly assigned to either the traditional corticotomy group (n=20) or the flapless corticotomy group (n=20). Patients underwent extraction of the maxillary first premolars, and orthodontic mini-screws were placed between the maxillary second premolars and the first molars for skeletal anchorage. An en-masse retraction was accomplished in both groups. Patients were asked to fill in a questionnaire at 24 hours (T1), four days (T2), seven days (T3), 14 days (T4), and 28 days (T5) after the surgical intervention using standardized questionnaires. Most questions were answered on a visual analog scale where zero scores meant the absence of pain, discomfort, or functional impairment, and 100 scores meant the worst feelings of these traits. RESULTS: All patients in both groups entered data analysis with no dropouts. All measured levels were significantly greater in the traditional corticotomy group during the first two weeks following the corticotomy intervention in terms of pain perception (P˂0.001), discomfort (P=0.004), and difficulty in chewing (P=0.015). Additionally, during the first week following corticotomy, levels of perception of discomfort (P˂0.001), difficulty in swallowing (P=0.001), and limitation of jaw movement (P˂0.001) were significantly greater in the traditional corticotomy group. Patient satisfaction, the recommendation to a friend, and acceptance of flapless corticotomy were significantly greater than traditional corticotomy (P=0.002, P=0.001, respectively). 78% of patients in the traditional corticotomy group considered it more discomfort than a tooth extraction, while 50% of patients in the flapless corticotomy group considered tooth extraction more discomfort, with a significant difference between the two groups (P=0.001). CONCLUSIONS: The levels of negative patients' reported outcomes were significantly smaller with flapless corticotomy than with traditional corticotomy. Traditional corticotomy was associated with mild to moderate levels of pain, swallowing difficulty, moderate levels of discomfort, chewing difficulty, and jaw movement limitation after 24 hours of the surgical procedure. In contrast, flapless corticotomy was less problematic and associated with mild pain, swelling, chewing difficulty, jaw movement limitation, and swallowing difficulty at the same assessment time. Patient satisfaction, acceptance, and recommendation to a friend were greater for flapless corticotomy than traditional intervention.

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OBJECTIVE: To evaluate the changes in surface morphology of two different types of mini-implants after clinical en masse retraction using scanning electron microscopy. MATERIAL AND METHODS: Fifty mini-implants of Dentos (Korea, Absoanchor, BH-1817-08) and Orlus (Korea, Yesanchor, C-1817) were inserted in patients in a split-mouth design who required en masse anterior retraction and absolute anchorage. Surface characteristics of mini-implants such as pitch (distance between consecutive threads), flank width (distance between root and crest), and taper were studied using scanning electron microscope (FEI nanosem450) before and after clinical use. RESULTS: Statistically significant difference (p value = 0.003) was found in a mean reduction of pitch dimension among the two groups with a mean difference of 25.000 µm. Also, a statistically significant difference was noted (p value = 0.001) in a mean reduction of flank width among Dentos implants as compared to Orlus implants. A statistically significant difference (p = 0.001) was seen in the mean reduction of taper dimension among Dentos group (0.0140 ± 0.02271) as compared to the Orlus group (0.0810 ± 0.05152). CONCLUSION: A marked reduction in surface morphology such as the pitch, flank width, and taper of both mini-implants after retrieval was observed. Dentos group of mini-implants displayed better dimensional stability post-retrieval as compared to the Orlus group of mini-implants. All the mini-screws showed milling defects in form of scratches on observation under scanning electron microscopy despite a smooth appearance to the naked eye.

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BACKGROUND: Shortening the duration of orthodontic treatment by speeding up the rate of tooth movement has become an essential goal for both orthodontists and patients. This preliminary report aimed to investigate the safety and effectiveness of a new intraoral removable electrical device in accelerating the en-masse retraction of the upper anterior teeth using low-intensity direct electrical current. METHODS: This prospective preliminary interventional clinical study was conducted at the Department of Orthodontics, Faculty of Dentistry, Damascus University, Syria, between March 2019 and February 2020. The sample consisted of six patients (four females and two males; mean age: 19.55 ± 0.89 years) whose initial diagnosis was class II division I malocclusion, and their treatment plan suggested the extraction of upper first premolars followed by en-masse retraction. The electrical stimulation was applied on the maxillary anterior region during the en-masse retraction phase using a specially fabricated removable device that was designed by two coauthors of this manuscript (RIS, MYH). Patients were asked to wear their own electrical devices inside their mouths for five hours daily. The primary outcomes were the en-masse retraction rate and duration. The secondary outcomes were safety and patient acceptance. RESULTS: The average total retraction rate during the treatment period was 0.97±0.06 mm/month. The total amount of retraction achieved during follow-up was 5.65 ± 0.85 mm, which was about 91.86% of the space resulting from the extraction of the upper first premolars. The mean treatment duration to complete the en-masse retraction was 5.66±0.81 months. No side effects of the electrical stimulation were found during the follow-up. CONCLUSIONS: Low-intensity direct electrical current could be an effective method to accelerate orthodontic movement. The electrical accelerating device used in this study effectively increased the en-masse retraction rate of the upper anterior teeth without any side effects and with high patient acceptance.

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INTRODUCTION: Present Finite-element-method (FEM) study evaluates the stress distribution values at the Temporomandibular-Joint (TMJ) during en-masse retraction of the mandibular dentition using buccal shelf bone screws with varying magnitudes of forces. MATERIAL AND METHODS: Nine replicas of a pre-existing three-dimensional finite element model of the craniofacial skeleton and articular disc from Cone-Beam-Computed-Tomography (CBCT) data and Magnetic-Resonance-Imaging (MRI) data of a patient were used. Buccal shelf (BS) bone screws were inserted buccal to the mandibular second molar region. Forces of magnitudes 250 gm, 350 gm and 450 gm were applied through NiTi coil springs along with stainless-steel archwires of sizes 0.016 × 0.022-inch, 0.017 × 0.025-inch and 0.019 × 0.025-inch. RESULTS: On the articular disc, the maximum stress was observed at the inferior region and the inferior part of the anterior and posterior zone at all force levels. The stress on the articular disc and displacement of teeth increased with increase in force levels in all the 3 archwires. The maximum stress at the articular disc and displacement of teeth was observed for 450 gm force and the least for 250 gm force. No significant difference in the amount of displacement of teeth or the stresses produced at the articular disc was seen with increasing the size of the archwire. CONCLUSION: With the present FEM study, we can deduce that it is better to use forces of lower levels on patients with temporomandibular-disorders (TMD) so as to reduce the stresses produced at the TMJ to avoid worsening of the TMD condition.

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OBJECTIVE: To compare rate and anchorage loss during en-masse retraction of anterior maxillary teeth between friction mechanics (FM) and frictionless mechanics (FLM). SETTING AND SAMPLE POPULATION: Thirty-eight patients requiring en-masse retraction of protruded anterior maxillary teeth were randomly allocated into FM and FLM groups. METHODS: En-masse retraction with sliding mechanics (FM) using an elastomeric chain was compared with continuous mushroom loop archwire mechanics (FLM). Study models and lateral cephalograms were taken before (T1) and immediately after retraction (T2). The primary outcome was the rate of en-masse retraction. Anchorage loss was the secondary outcome. Intergroup comparison was performed using an independent t test (P < .05). RESULTS: Baseline characteristics were similar between groups. Thirty-six patients completed the trial. Two patients were lost to follow-up in the FLM group. The rate of en-masse retraction did not differ significantly (P = .625) between FM (0.7 mm/mo) and FLM (0.8 mm/mo) groups. The intragroup comparison showed significant anchorage loss in FM (2.28 mm) and FLM (1.13 mm) groups; however, the intergroup comparison showed no statistically significant difference (P = .093). Maxillary first molar showed a statistically significant change in angulation between the two mechanic groups (P < .001). Vertical movement of the maxillary incisor and first molar showed no significant difference between FM and FLM groups (P = .143, P = .546, respectively). CONCLUSIONS: The rate of en-masse retraction and anchorage loss was comparable between the FM and FLM groups. Significant anchorage loss was seen with both mechanics. The result suggests that both the mechanic group require external reinforcement to prevent anchorage loss.

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Background This study aimed to evaluate the levels of pain and discomfort associated with employing mini-implants as a temporary skeletal anchorage device compared to the traditional transpalatal arches (TPAs) during upper anterior teeth retraction in patients with upper dentoalveolar protrusion and to determine the level of acceptance of both techniques among patients. Methodology The study sample consisted of 38 patients (29 women and nine men) with an average age of 21.7 years. The patients were randomly and equally distributed into two groups. In the first group: upper anterior teeth were en-masse retracted using mini-implants (the TAD group), whereas, in the second group, TPAs were used during the two-step retraction of upper anterior teeth (the TPA group). Standardized questionnaires were distributed to all patients after 24 hours of mini-implant application. The questionnaire asked the patients to rate their pain perception, swelling sensation, eating difficulties, talking impairments, and cleansing difficulties on a four-point Likert scale on the third-day, one-week, two-week, and one-month follow-ups after the anchorage application. Wilcoxon matched-pairs signed-rank tests were used to evaluate intragroup changes, whereas Mann-Whitney U tests were employed to examine intergroup differences. Results Patients in the TAD group had higher pain and swelling levels than those in the TPA group, and differences were statistically significant at the first three assessment time points. The differences between the two groups were statistically insignificant regarding eating and talking difficulties, whereas differences were statistically significant for brushing difficulties. These impairments decreased to almost normal levels after one month of treatment initiation. Conclusions TPAs, when used for anchorage in the two-step retraction technique, were less problematic compared to mini-implants with en-masse retraction, where the sensation of pain or swelling around the mini-implants did not last for more than a week. The difficulties of cleaning, chewing, and speaking in the presence of mini-implants were temporary and mostly disappeared within two weeks of mini-implant application.

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BACKGROUND: Micro-osteoperforations (MOPs) as a surgical technique is increasingly being used as a method to enhance orthodontic tooth movement. However, its iatrogenic effects on root and alveolar bone morphology have been less studied. OBJECTIVE: This parallel-groups single-centered trial aimed to assess the impact of micro-osteoperforations (MOPs) on orthodontically induced inflammatory root resorption (OIIRR) and alveolar bone during en-masse retraction stage of maxillary and mandibular anterior teeth. METHODS: Fifty-two patients (mean age 21.35±2.2 years) with Class I bi-dentoalveolar protrusion, requiring all 1st premolar extractions and miniscrews for anchorage, were randomly distributed into two groups (n=26 each): MOP group treated using single application of MOP's and control group treated with routine sliding mechanics, for en-masse retraction. The primary outcomes were assessed using CBCT-based measurements. RESULTS: Anterior teeth in MOP group showed increased mean OIIRR than control group, though the difference was statistically non-significant [maxillary anteriors, MOP group - OIIRR=0.78±0.29mm and control group OIIRR=0.73±0.36mm; mandibular anteriors, MOP group - OIIRR=0.733±0.20mm and control group OIIRR=0.70±0.24mm]. Levander and Malmgren's Index for objective scoring of OIIRR revealed only mild resorption with most teeth in both the groups (47% and 51%, respectively). Lateral incisors showed highest OIIRR followed by central incisors and canines in both groups. Lingual side bone thickness and height decreased significantly, however, the differences between the two groups were non-significant (P>0.05). CONCLUSION: Within the settings of the current RCT, en-masse retraction when combined with single application of micro-osteoperforations did not pose an increased risk of root resorption or alveolar bone changes compared to routine sliding mechanics.

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BACKGROUND: Orthodontic treatment is commonly more time-consuming in adults than in teenagers, especially when it comes to the maxillary en-masse retraction, which may take 9 months or even longer. As to solve this concern, orthodontists have been striving to seek new methods for shortening orthodontic treatment time. Piezocision, as a popular alternative treatment, has been widely used in different types of tooth movement. However, its effect on en-masse retraction of maxillary anterior teeth remains unclear. This randomized controlled trial intends to figure out the role piezocision plays in accelerating en-masse retraction. METHODS: This protocol is designed for a prospective, single-center, assessor-blinded and parallel-group randomized controlled trial. Twenty adult patients aged from 18 to 40 whose orthodontic treatment required bilateral maxillary first premolars extraction will be randomly assigned to the piezocision group and the control group at a ratio of 1:1. The piezocision group will undergo en-masse retraction immediately after the piezo surgery, while the control group will start en-masse retraction directly. Both groups will be followed up every 2 weeks to maintain the retraction force until the end of space closure. The space closing time is set as the primary endpoint. Meanwhile, the secondary endpoints include the change of root length, labial and palatal alveolar bone thickness, vertical bone height, probing depth of maxillary anterior teeth, cephalometric measurements, visual analogue scale, and postoperative satisfaction questionnaire. DISCUSSION: This study will attempt to provide more convincing evidence to verify whether piezocision will shorten the time of en-masse retraction or not. Distinguished with previous studies, our study has made some innovations in orthodontic procedure and primary outcome measurement, aiming to clarify the efficacy and safety of piezocision-assisted en-masse retraction in Chinese population. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR 1900024297 . Registered on 5 July 2019.

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Aims: This finite element study was undertaken to evaluate the pattern of stress distribution around the implant and anterior teeth during en-masse retraction in the premolar extraction case. Displacement of the teeth and play of wire in the bracket slot were also evaluated to determine the most favorable height of the power arm attached to the arch-wire. Materials and methods: A three-dimensional (3D) finite element model of the maxilla was constructed using computed tomography (CT) scan. A total of 12 models were fabricated with different heights of power arms placed distal to the canine. A retraction force of 1.5 N was applied from the implant placed between the roots of the second premolar and first molar, and the response was predicted using Analysis of Systems (ANSYS) software. Results: When power-arm height was near the center of resistance of the anterior segment, stability in the stress distribution around the implant site and anterior teeth was observed. Displacement of the teeth varied along the three planes of space with the change in power-arm height. Conclusion: For en-masse retraction, power-arm height should be kept at a level of the center of resistance. Play in the bracket slot and the archwire show a negative role in the bodily movement of anterior teeth. Clinical significance: For efficient en-masse retraction of anterior teeth, it is imperative to study the most effective site of application of force. Therefore, our study recommends certain key points to keep in mind during the attachment of the power arm and engaging wire in the bracket slot, which could benefit the orthodontist immensely. How to cite this article: Singh H, Khanna M, Walia C, et al. Displacement Pattern, Stress Distribution, and Archwire Play Dimensions during En-masse Retraction of Anterior Teeth using Sliding Mechanics: A FEM Study. Int J Clin Pediatr Dent 2022;15(6):739-744.

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BACKGROUND: Micro-osteoperforations is one of the non-invasive surgical techniques used in attempt to accelerate OTM. Conflicting reports on its effectiveness has been reported in the literature. OBJECTIVES: The objectives of this trial were to investigate the effect of micro-osteoperforations on the rate of space closure and on molar anchorage loss during mini-implant supported maxillary anterior en-masse retraction. TRIAL DESIGN: A single center, parallel arm, randomized controlled trial was conducted. METHOD: Sixty, male and female subjects (age range 16-25 years) having Class I bimaxillary protrusion or Class II div 1 malocclusion, who required fixed mechanotherapy with either upper 1st premolar or all four 1st premolar extractions were allocated into two groups using 1:1 allocation ratio. The allocation was done by block randomization method with a block size of 6. In the experimental group, 5 MOPs per side were performed only once just before the en-masse anterior retraction. Mini-screws were placed in order to obtain maximum anchorage. Impressions were taken every month till 4 months and rate of space closure was measured on 3D study models. RESULTS: Data of 27 subjects in control (attrition â€‹= â€‹3) and 28 subjects in experimental group (attrition â€‹= â€‹2) were analyzed at the end of this trial. There was a statistically significant increase in the rate of en-masse retraction for the 1st month(p â€‹= â€‹0.001,95%CI, 0.17, 0.37 â€‹mm) but there was no statistically significant difference for the subsequent 2nd (p â€‹= â€‹0.450,95%CI,0.13,0.43 â€‹mm), 3rd(p â€‹= â€‹0.204,95%CI,0.23,0.47 â€‹mm) and 4th month (p â€‹= â€‹0.680,95%CI,0.21,0.41 â€‹mm) between experimental and control groups. There was also no difference (p â€‹> â€‹0.05) in molar anchorage loss between both groups at all time intervals. CONCLUSION: Micro-osteoperforations (MOPs) did not accelerate the rate of anterior en-masse retraction over a period of 4 months; however, it temporarily increases the rate of retraction only for first month and no affect on molar anchorage. TRIAL REGISTRATION: The trial was registered at www.ctri.nic.in with CTRI No- CTRI/2019/03/018140).

RESUMEN

OBJECTIVE: The extent to which the modelling behaviour of the anterior alveolus limits tooth movement remains unclear. Will the labial and lingual cortical plates model as incisors retract, or will they remain unchanged, therefore limiting the extent of possible tooth movement? SETTING AND SAMPLE POPULATION: Pre- and post-treatment lateral cephalometric radiographs of 29 bimaxillary protrusive patients of South Korean descent were examined. Treatment consisted of two premolar extractions in one or both arches with en masse retraction of the incisors using miniscrew anchorage. MATERIALS AND METHODS: Pre- and post-treatment measurements of both tooth and cortical plate position were made at various increments along the length of the root and then compared using paired t tests. RESULTS: Despite the use of miniscrew anchorage, the incisors were retracted by controlled tipping. The labial cortical plates in both arches modelled to follow tooth movement. Following retraction of the incisors in the maxilla, the incisor root approached the lingual cortical plate, which remained unchanged. In the mandible, the lingual cortical plate position was unchanged except at the level closest to the cementoenamel junction. CONCLUSIONS: The maxillary and mandibular lingual cortical plates did not model to follow the incisor movement while the labial cortical plates did. These findings suggest that lingual cortical plates may act as limitations to planned orthodontic tooth movement.

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