Incisor Position Research Articles

The research on the effect of temperature of electro-surgical unit to surgical smoke distribution in theatre-in vitro and simulation study.

In electro-surgery, surgical smoke was hazard to surgeons and patient in theatre. In order to institute effective countermeasures, quantifying of the effect of tip temperature of electro-surgical unit to surgical smoke distribution in theatre was studied. The relation of tip temperature to power of electro-surgical unit through in vitro cutting experiment. Based on experiment data, the mathematical model was established to simulate the electro-surgery in laminar operation room. As the power of electro-surgical knife increased, the knife tip temperature increased. Total content of (CO, CO2, CH4, NH3) in waste gas and net flow rate of waste gas at outlet increased with the rising temperature of knife tip and formation rate of condensed tar droplets and non-viable particles also increased. Based on simulation, it was found that The maximum height of surgical smoke rising right above the incision of electro-surgical unit was increased with rising temperature of electro-surgical knife tip. There was a spread route of dispersed surgical smoke near the walls of theatre through natural convection. The polynomial fitting relationship was derived. As the tip temperature of knife increased from 200 to 500°C, maximum ascending height of surgical smoke right above the incision position of electro-surgical unit increased from 1.1 m to 1.45 m. When the tip temperature of electro-knife was more 400°C, the CO content in the surgeon's operating zone was more than 200 ppm, which would cause the surgeon's HbCO level increased. As the patient's tissue in the wound during operation was open, when the electro-knife of more than 400°C, the content of condensed tar droplets and in-viable particle was higher than 20 g/m3 and 12 g/m3 in the zone around patient's wound of open tissue, which should be hazard to health of patient.

Developmental characteristics of the permanent upper lateral incisor in unilateral cleft lip and palate

ObjectivesThis study aims to provide insights into the developmental characteristics of the upper lateral incisor in individuals with unilateral clefts.Materials and methodsPanoramic radiographs of a consistent group of Caucasian children taken over time (ages 6, 9, and 12) were extensively reviewed. The study assessed the distribution pattern, eruption path, tooth development, and crown size of the upper lateral incisor within the cleft region.ResultsThe most commonly observed distribution pattern was the lateral incisor located distal to the cleft, accounting for 49.2% of cases. Furthermore, a significant delay in tooth development of the upper lateral incisor on the cleft side was noted at ages 6 and 9 (p > 0.001). Compared with the non-cleft side, these incisors often erupted along the alveolar cleft and exhibited microdontia (88.3%, p < 0.041).ConclusionLateral incisors on the cleft side display unique distribution patterns, microdontia, and delayed tooth development. Careful monitoring of the cuspid eruption is essential, as it can influence the eruption of the lateral incisor.Clinical relevanceA comprehensive understanding of the development of the upper lateral incisor relative to the cleft is vital for determining its prognosis over time. The position of the upper lateral incisor can also influence the timing and prognosis of secondary alveolar bone grafting. Preserving the upper lateral incisor favors arch length, perimeter, and symmetry in individuals with unilateral clefts.

Forced Esthetic Position: A Diagnostic Strategy for Anteroposterior Repositioning in Orthognathic Surgeries.

Considering the esthetic goals involved in orthognathic surgeries, one of the challenges is to define the horizontal projection of the jaws. Most of the cephalometric analyses are focused on the position of the upper incisor and upper lip. Planning the correction of a mandibular retrognathism can be simplified by clinical simulation asking the patient to project their mandible. A forced esthetic position protocol is presented as a starting point for the planning in orthognathic cases.

Sagittal Position of the Upper Incisor in Relation to the Forehead in Peruvian Individuals with Different Skeletal Relationships.

The aim of this study was to determine the sagittal position of the upper incisor considering Andrews' analysis based on the position of the forehead in Peruvian individuals with different skeletal relationships. This retrospective, cross-sectional study included 212 lateral head radiographs of Peruvian individuals (males: 85, mean age 21.38 ± 6.88, and females: 127, mean age 21.18 ± 6.95), with different skeletal relationships (Class I group = 96, Class II group = 57, Class III group = 59). The values of the ANB, SNA, SNB angles as well as the forehead anterior limit line (FALL) and goal anterior limit line (GALL) points were identified in the radiographs, and then a vertical line was drawn in each point to determine if the upper incisor was positioned forward (protruded), backward (retruded) or within (adequate) these lines. Two trained and calibrated investigators performed all the measurements. The Chi-square test was used to evaluate associations. A p-value < 0.05 was considered statistically significant. Overall, the sagittal position of the upper incisor showed a significant association with the sagittal skeletal relationship (p = 0.001). The upper incisors showed an adequate position (41.7%), protruded position (56.10%), and retruded position (42.40%), for Class I, II, and III skeletal relationships, respectively, as highest percentages in each Class. Statistical significance was found for females only (p = 0.005). Skeletal Class I mainly showed an adequate position of the upper central incisor, whereas for Class II a protruded position was most frequently found, and Class III presented a retruded position. Andrews' analysis based on the position of the forehead in Peruvian individuals is a valuable tool for orthodontic diagnosis. How to cite this article: Bazán-Mendoza JR, Arias-Modesto PB, Ruíz-Mora GA, et al. Sagittal Position of the Upper Incisor in Relation to the Forehead in Peruvian Individuals with Different Skeletal Relationships. J Contemp Dent Pract 2023;24(11):821-825.

Recovery bone formation on radiographic palatal bone dehiscences after incisor retraction with microimplants.

To investigate the difference in labial and palatal alveolar bone thickness and height during the retention period after incisor retraction treatment with microimplant. A sample of 21 patients (mean age: 17.80 ± 4.38 years) who underwent incisor retraction treatment using microimplants after premolar extraction was investigated. The cone-beam computed tomography images at pretreatment, posttreatment, and retention were used to measure anterior alveolar bone thickness (labial, palatal, and total; at three vertical levels) and height (labial and palatal) and differences in the incisor position during treatment or retention. Repeated-measures analysis of variance with Bonferroni correction was performed to compare the variables at T0, T1, and T2. The maxillary central incisor moved posteriorly by approximately 8.0 mm along with intrusive movement of 1.8 mm after treatment. The alveolar bone thickness significantly decreased on the palatal side and increased on the labial side after treatment. Thereafter, the palatal bone thickness significantly increased and labial bone thickness decreased during the retention period. The palatal interdental bone depressed by incisor retraction showed substantial bone deposition after retention. Radiographic palatal bone dehiscences on the incisor root and palatal bone depression between the incisor roots were apparent after treatment. This palatal bone loss around the incisor roots noticeably recovered with newly formed bone during retention.

Application of the "3-2-1" body surface localization method in intertrochanteric femoral fractures: a technical note.

In femoral intertrochanteric fractures, poor incision positioning may result in inaccurate intramedullary nail placement direction, which increases the difficulty of reduction and thus the size and number of incisions. Repeated intraoperative fluoroscopy not only increases the radiation exposure of the surgeon but also affects the operative outcomes. This technical note proposes a method of identifying incision positioning preoperatively using the "3-2-1" body surface localization method. This auxiliary positioning technique uses a body surface locator and the lower limb force axis. It can predict the incisions for the needle insertion point, spiral blade, and locking nails, create minimally invasive incisions, avoid incorrect incision position, facilitate accurate intraoperative intramedullary nail placement, reduce the incision size, intraoperative bleeding, and radiation exposure, and improve surgical efficiency and reduction quality.

Анкетування як важливий інструмент для виявлення факторів впливу на затримку прорізування зубів

Aim. To identify risk factors for delayed eruption of permanent anterior teeth in children aged 7 to 14 years, based on clinical examination, radiological examination, parental/caregiver questioning. Materials and Methods. The study included Ukrainian children aged 7-14 years who had delayed eruption of permanent teeth. They were divided into two groups. Group I was composed of 56 (40.0%) children aged 7-9 years with early mixed dentition; Group II was made of 84 (60.0%) individuals aged 10-14 years who had the final stage of mixed dentition. After careful history taking and physical examination, a clinical examination was performed to identify abnormal positions of incisors or canines and to determine the condition of the oral cavity and the bite; a radiological examination included CBCT; and the children’s parents /caregivers were surveyed with the use of the questionnaire we had developed. Results. It has been established that the main risk factors for delayed eruption of permanent teeth are arch-length deficiency, recurrent colds, respiratory disorders, delay in chewing food, pathology in the first trimester of pregnancy, premature extraction of primary teeth, use of a pacifier, delayed loss of deciduous teeth, bad habits, allergies, formula and mixed feeding, orthodontic treatment in the parents’ history, ectopic teething, and injuries to the maxillofacial area in children. Conclusions. A comprehensive history taking, an appropriate determination of the stages of dental development and an assessment of the potential risks of delayed teething are of paramount importance in the diagnosis of pathology, as they allow for the prediction of future orthodontic complications. Key words: delayed eruption of permanent teeth, questionnaire, X-ray examination, dental trauma, ENT pathology, bad habits, CBCT, early loss of primary teeth, allergy, burdened family history, stressor.

Upper incisor position in the sagittal plane when smiling. A photographic and CBCT study.

The aim of this study was to analyze the anteroposterior position between the upper incisors (UI) and the soft tissues based on photographs in which the head has been oriented along the Frankfort Horizontal Plane. Restrospective case-control study carried out by analizing photographic and CBCT images of 109 patientes. The sample was divided into 4 different groups: 21 normocclusive (N), 29 Class II/1st, 29 Class II/2nd y 30 Class III. All patients were positioned using the Frankfurt plane (FH). From this aligned position of the head, a vertical line was drawn perpendicular to the FH passing through the Soft-Tissue Nasion (LN), and the distance in centimeters from of the UI to this vertical line was measured on both the CBCT and the photo of the patient's profile. The UI was located in front of the LN in the groups N, Class II/1st y Class III (0,4, 0,2, 0,1cm respectively) and behind the LN in the group Class II/2nd (0,2cm). There were significant differences between the Class II/2nd and Normocclusive groups and Class II/2nd and Class II/1st (p<0.001 y p=0.004 respectively). Orthodontic and/or surgical correction of various malocclusions can be planned based on the position of the UI with respect to the LN established in Normocclusive patients. Key words:Upper incisors, facial profile, CBCT, photograph, Frankfurt plane, Soft-Tissue Nasion.

Measurement of distance between maxillary central incisors and incisive papilla in dentate individuals.

Objective: To measure the distance amongst the incisive papilla’s centre and posterior border to the incisal edge of the upper central incisors in dentate individuals.Methodology: This descriptive cross-sectional study was conducted at Department of Prosthodontics at Isra Dental Col-lege, Hyderabad from May, 2020 to Feb, 2021. During study period, 200 patients aged between 20-40 years of either gender were included. Impressions and casts made. On the cast and distance measured and recorded for maxillary central incisor and incisive papilla with the help of vernier calliper.Results: Mean distance between maxillary central incisive papilla’s centre was 9.20mm while it was 12.47mm from up-per incisor to the incisive papilla’s posterior border. Distance among the maxillary central incisor to the incisive papilla’s center and posterior border were significant statically in both genders.Conclusion: While fabricating removable prosthesis, the results of current study may used as primary point for position of maxillary incisors.&#x0D; Key words: Anatomical landmarks, Central incisors &amp; Incisive papilla. Removeable prosthesis

Assessing inter- and intra-examiner reliability of orthodontists in devising incisor position objectives on cephalograms: a comparative study between senior and junior practitioners

BackgroundEffective orthodontic treatment planning hinges on accurately defining incisor position objectives (IPO) in cephalograms. The purpose of this study was to estimate the inter-examiner and intra-examiner reliability of different orthodontists in devising IPOs on cephalograms.MethodsTen orthodontists, who were divided into to the senior group (N = 5) and the junior group (N = 5) based on their clinical experience, formulated IPOs for 60 pre-treatment cephalograms twice with an interval of 2 weeks, utilizing SmartOrtho software. The type and magnitude of movement were read directly in the software. A paired t-test assessed the absolute differences between the first and second IPO devising within each group and between the senior and junior groups in each time’s IPO devising. The intra-examiner and inter-examiner reliabilities were calculated.ResultsThere were significant differences in all types of upper incisor movement and lower incisor protrusion/retraction movement between the first and second IPO devising of the senior group. The junior group exhibited significant differences in the twice the upper incisor extrusion/intrusion movement and upper incisor torque movement devising. Additionally, significant differences in all types of incisor movement between the senior and junior groups in each time’s IPO devising. Intra-examiner reliabilities were excellent for both two groups and moderate for the junior group in most types of incisor movement, respectively. The inter-examiner reliability between the two groups ranged from moderate to good across different types of incisor movement.ConclusionsAmong orthodontists, both senior and junior practitioners displayed the best inter-examiner reliability in lower incisor extrusion/intrusion movement. In terms of intra-examiner reliability, senior orthodontists had better intra-examiner reliability in upper incisor position objectives devising than the junior orthodontists. Furthermore, senior orthodontists tended to adopt a more recessive, intrusive, and lingually torqued incisor position approach compared to junior orthodontists.

Morphological Evaluation of the Incisive Canal in the Aspect of the Diagnosis and Planning of Orthodontic Treatment—CBCT Study

Background: Understanding the anatomy of the incisive canal is crucial for effective diagnosis and treatment planning in clinical orthodontics. This is because, during orthodontic tooth movement, there is a risk of contact between the roots of the upper central incisors and the incisive canal. Objective: The aim of this study was to assess the anatomical variability of the incisive canal using cone beam computed tomography (CBCT), as well as to evaluate its correlation with age, sex, and the position of the maxillary central incisors. There are only a few studies on this topic. Materials and methods: We analysed CBCT data from 67 patients aged from 13 to 49 years. This study was conducted at the Wroclaw Medical University. Measurements were performed twice by two independent researchers, and intra-observer error and correlation were calculated. The mean difference between the first and second observations and between observers was also assessed. We examined the dimensions of the incisive canal and its relationship to the roots of the upper central incisors in relation to age and gender. Results: Our study results revealed a significant correlation between the width and length of the incisive canal. Males exhibited a significantly greater canal length at the lowest point of the incisive canal on the palatal wall. Additionally, males had wider canals compared to females. The analysis of canal width and distance between the most mesial point of the root and the line passing through the most anterior point of the incisive canal showed a negative correlation in all age groups of men. The analysis of incisal inclination and incisal canal inclination showed a very strong relationship, especially in the age group of 13 to 20 years. Several potential risk groups of contact between the roots of central incisors and the incisive canal have been identified based on their structure and the planned incisors’ orthodontic movement. Conclusions and implications: Knowledge of the anatomy of the incisive canal and the use of 3D imaging in high-risk patients can prevent resorption of the incisor root by considering the individual anatomical conditions of the patient when planning orthodontic tooth movement. We recommend performing a CBCT scan before starting orthodontic treatment in the case of moderate and significant retraction of the incisors, or a significant change in their inclination due to the wide anatomical diversity of the incisive canal, especially in adult patients.

Development and Validation of a Predictive Model to Evaluate the Risk of Dysphagia Following Anterior Cervical Discectomy and Fusion.

A retrospective study. To investigate the potential risk factors of dysphagia after anterior cervical discectomy and fusion (ACDF) and to establish and validate a prediction model. The clinical data of 252 patients who underwent anterior cervical discectomy and fusion in our hospital from January 2018 to October 2020 were retrospectively analyzed and divided into the dysphagia group and the non-dysphagia group according to whether dysphagia occurred after surgery. Age, gender, body mass index, smoking and drinking history, hypertension history, diabetes history, disease duration, placement of Hemovac negative pressure drain, number of segments involved in surgery, whether C4-5/C5-6 segment surgery, incision length, incision position, level of preoperative EAT-10 score, whether preoperative tracheal exercise, and changes in cervical curvature before and after surgery were recorded in both groups. Risk factors for postoperative dysphagia were identified and nomogram prediction models were developed. A total of 252 patients were included in the study, 115 of whom presented with dysphagia within 1 week after anterior cervical fusion. The results of multivariate logistic regression analysis indicated that male gender (OR = .045, 95% CI .223-.889) and whether preoperative tracheal exercise (OR = .260, 95% CI .107-.633) were independent risk factors associated with reduced incidence of postoperative dysphagia. The incidence of dysphagia symptoms after anterior cervical decompression and fusion gradually decreased with the extension of follow-up time, and preoperative tracheal exercise and shortening the operation time may help to reduce the occurrence of postoperative dysphagia.

Esthetic rehabilitation of mutilated maxillary anterior alveolar segment by combining orthodontic osseous distraction and implant-supported crowns: A clinical report

Bony defects in the esthetic zone, especially in the maxillary anterior region, increase the complexity of surgical and prosthetic procedures. Moving teeth with preprosthetic osseous distraction techniques can be an alternative nonsurgical option to traditional regenerative or reparative surgical therapies to increase bone volume. Healthy peri-implant bone, periodontium, and adjacent teeth provide a favorable environment for implant restorations. The esthetic rehabilitation of the maxillary region after the removal of 2 ankylosed central incisors is presented. The lateral incisors were moved mesially to the central incisor positions, and implants placed in the lateral incisor positions after new healthy bone had been induced.

Position of the lower incisor in patients of skeletal class I and II according to their facial biotype in a sample from a private clinic, Cali 2014 - 2020

Introducción: la sínfisis mentoniana es la articulación cartilaginosa medial de los huesos mandibulares, su posición se relaciona con los diferentes biotipos y puede influir en la posición del incisivo inferior. Objetivo: determinar si existen variaciones en la posición del incisivo inferior, en pacientes clase II con diferentes biotipos. Materiales y métodos: se evaluaron la totalidad de tomografías de pacientes clase I y II esquelética que asistieron entre 2014 y 2020 a una clínica privada, teniendo una muestra total de 74 pacientes, caracterizándolos por sexo y edad. Se determinó biotipo facial, Incisor Mandibular Plane Angle, distancias a la sínfisis como el ACV-ACL y altura desde el ápice. Para el análisis se utilizó I-CAT Visión Q, para las medidas de las tomografías digitales y para el análisis estadístico Stata 17. Resultados: se encontró un Incisor Mandibular Plane Angle mayor en pacientes clase II en los tres biotipos; los dolicofaciales clase II mostraron menor valor en corticales ACV–ACL, los pacientes mostraron mayor proinclinación en la clase II. La posición del incisivo en pacientes clase II presenta una proinclinación significativa en braquifaciales (p = 0.04). Conclusión: se encontraron variaciones entre los tres biotipos faciales en las diversas mediciones en pacientes clase I y II, el sexo femenino evidenció diferencias significativas en las clases en las medidas del Incisor Mandibular Plane Angle y la altura de la sínfisis a nivel del ápice; estos hallazgos son relevantes en el momento de realizar un tratamiento ortodóntico ya que puede limitar el movimiento de los incisivos inferiores.

Reliability of Software Prediction of Post Orthodontic Treatment Changes

Aim The aim of this study was to assess the accuracy of Dolphin VTO prediction in patients requiring extraction treatment by comparing the VTO-predicted values and post-treatment values. Method Digital pre and post-treatment lateral cephalograms of 52 patients having Class I bimaxillary protrusion were taken and transferred in Dolphin Imaging software for analysis and VTO prediction. A composite analysis was made containing 17 dental and soft tissue parameters (Holdaway, Mc Namara, Rakosi, Steiners, and Tweed analysis). Results A comparison between post-treatment and VTO-predicted values showed that software was able to predict soft tissue changes accurately in regions such as nose, inferior sulcus depth, and chin region ( p &gt; .05). In dental changes, software was able to predict the inclination of upper incisors to Sn and palatal plane correctly ( p &gt; .05). Parameters for other areas such as upper and lower lip, position of upper and lower incisor show significant difference in their VTO and post-treatment values ( p &lt; .05) showing inaccuracy of the software. Conclusion The VTO prediction of dental and soft tissue changes was significantly different from the post-treatment values for parameters such as superior sulcus depth, lower lip to h line, subnasal to h line, upper lip thickness, lip strain, nasolabial angle, interincisal angle, Ui-NA, Li-NB, and IMPA. For nasal prominence, inferior sulcus depth, chin thickness, UI-SN, and UI-PP, there was no significant difference seen. Since, for most of the parameters, a significant difference was found between the post-treatment and the predicted values, so it was inferred that the software-based VTO prediction could not be fully relied for any treatment planning.

Skeletal and dento-alveolar changes obtained with customised and preformed eruption guidance appliances after 1-year treatment in early mixed dentition.

The aim of this study was to assess the skeletal and dento-alveolar changes produced by a customised eruption guidance appliance (EGA) and a preformed EGA in subjects presenting a skeletal class II pattern during early mixed dentition and to evaluate the differences between the two devices. All subjects included in the study were randomly selected from the record's archive according to the following inclusion criteria: (1) patients presenting upper central incisor and first permanent molars fully erupted; (2) early mixed dentition with age between 7 to 9 years old; (3) Angle class I or class II malocclusion; (4) increased overjet > 4 mm;(5) deep bite with at least 2/3 overlapping of the incisors; (6) no previous orthodontic treatment apart from maxillary expansion treatment. All children belonging to the case group received treatment with a 3D printed EGA whereas the other patients belonging to the control group were treated with preformed EGA. Records consisted in digital dental models and lateral cephalogram at the beginning (T0) and after 1 year of treatment (T1). Data collected on the digital models included the dentoalveolar changes in overbite, overjet, sagittal molar relationship, and dental crowding. Cephalometric tracings were computed by a single blinded observer using Dolphin Imaging software. Statistical analysis was performed with SPSS (version 25.00; IBM Corp, Armonk, NY). Comparison regarding the cephalometric changes between T1-T2 was carried out with paired t-test. Difference in distribution regarding sagittal molar and canine relationship and anterior crowding between groups at T1 and T2 has been computed with chi-square test. The independent sample t-test was used to perform the between group comparison. In the short time, both the appliances showed to be effective in correcting class II malocclusion, anterior crowding, overjet and overbite. Custom-made appliance demonstrated to be significantly more effective in correcting anterior crowding, the dento-skeletal vertical relation and position of permanent incisor compared to the preformed appliance. Adopting a customised device, effects due to an average prescription appliance used to a specific patient can be reduced, resulting in more predictable results.

144. OPTIMIZING MEDIASTINAL ACCESS FOR RADICAL ESOPHAGECTOMY: A BILATERAL CERVICAL AND TRANSHIATAL APPROACH TO RESECT ESOPHAGEAL CANCER

Abstract Background Major medical centers have gradually attempted and promoted esophagectomy via mediastinal approach. However, this operation is challenging and requires a high level of technical proficiency from surgeons because of the limited space and restricted visibility of the mediastinum. The current surgical method limits its application in patients with locally advanced esophageal cancer, which underscores an urgent need for optimization to facilitate its refinement and dissemination. Methods We have implemented the following enhancements to the surgical procedure: 1. The cervical level was chosen for transecting the esophagus, and then the proximal esophageal stump was pulled down and invaginated. 2. Bilateral cervical incisions were made, with a small 0.5 cm incision at the anterior edge of the right sternocleidomastoid muscle. 3. The position of abdominal surgical incisions was adjusted so that all incisions were located on the left side of the abdominal midline. 4. A portion of the left diaphragm was dissected. 5. During the superior mediastinum procedure, gauze was positioned within the expanded superior mediastinum. Results 1. The surgical field was fully exposed, expanding the operative space for upper mediastinal surgery. 2. The difficulty of this surgery was reduced, and it was easier to expose both RLNs and completely remove the mediastinal lymph nodes. 3. The 106recR could be completely removed under endoscopy. 4. The thoracic duct could be fully exposed and freed. 5. During surgery, gauze is placed in the upper mediastinum to aid in hemostasis and improve visibility. 6. Even if the tumor was slightly larger or locally invaded surrounding tissues, it could be completely resected. 7.Complete resection of the esophageal mesorectum was successfully achieved. Conclusion Esophagectomy for esophageal cancer via bilateral cervical and transhiatal approach can achieve radical resection and can be applied to patients with locally advanced esophageal cancer. This surgical method expands the surgical indications, reduces the surgical difficulty for surgeons, and facilitates the promotion and popularization of the mediastinal approach surgery.

175. OPTIMIZING MEDIASTINAL ACCESS FOR RADICAL ESOPHAGECTOMY: A BILATERAL CERVICAL AND TRANSHIATAL APPROACH TO RESECT ESOPHAGEAL CANCER

Abstract Background Major medical centers have gradually attempted and promoted esophagectomy via mediastinal approach. However, this operation is challenging and requires a high level of technical proficiency from surgeons because of the limited space and restricted visibility of the mediastinum. The current surgical method limits its application in patients with locally advanced esophageal cancer, which underscores an urgent need for optimization to facilitate its refinement and dissemination. Methods We have implemented the following enhancements to the surgical procedure: 1. The cervical level was chosen for transecting the esophagus, and then the proximal esophageal stump was pulled down and invaginated. 2. Bilateral cervical incisions were made, with a small 0.5 cm incision at the anterior edge of the right sternocleidomastoid muscle. 3. The position of abdominal surgical incisions was adjusted so that all incisions were located on the left side of the abdominal midline. 4. A portion of the left diaphragm was dissected. 5. During the superior mediastinum procedure, gauze was positioned within the expanded superior mediastinum. Results 1. The surgical field was fully exposed, expanding the operative space for upper mediastinal surgery. 2. The difficulty of this surgery was reduced, and it was easier to expose both RLNs and completely remove the mediastinal lymph nodes. 3. The 106recR could be completely removed under endoscopy. 4. The thoracic duct could be fully exposed and freed. 5. During surgery, gauze is placed in the upper mediastinum to aid in hemostasis and improve visibility. 6. Even if the tumor was slightly larger or locally invaded surrounding tissues, it could be completely resected. 7.Complete resection of the esophageal mesorectum was successfully achieved. Conclusion Esophagectomy for esophageal cancer via bilateral cervical and transhiatal approach can achieve radical resection and can be applied to patients with locally advanced esophageal cancer. This surgical method expands the surgical indications, reduces the surgical difficulty for surgeons, and facilitates the promotion and popularization of the mediastinal approach surgery. Video address: https://www.icloud.com.cn/iclouddrive/085wyZDN6Qqm6Ou06fhOsi-Rw#2023_ISDE_abstract_video

Soft tissue and incisor position changes in class I bimaxillary subjects after retraction using friction and frictionless mechanics

Aim: Bimaxillary protrusion is a common condition observed irrespective of race and ethnicity and is a chief concern for patients who seek orthodontic treatment. The aim of this study was to compare and evaluate changes in soft tissue structures and incisor positions in class I bimaxillary protrusion subjects undergoing orthodontic therapy when friction and frictionless mechanics were used. Methods: Two groups with a total of 40 patients aged 18–30 years diagnosed with class I bimaxillary protrusion treated by extracting first premolars were considered for this study. Patients treated with friction mechanics were included in Group 1 and those treated with frictionless mechanics in Group 2. The digital lateral cephalograms were calibrated and analyzed using Nemoceph software. Selected landmarks were marked on pre- and post-treatment cephalograms and assessed for intra- and inter-group soft tissue and incisor position changes. Student’s t-test was used to analyze the collected data using SPSS 20 software. Result: Intragroup comparison revealed significant changes in both groups. Inter-group comparison of the selected parameters between groups 1 and 2 showed differences but without any statistical significance, except for the inter-incisal angle. Conclusion: Pre- and post-treatment comparison analysis revealed significant soft tissue changes in both groups. However, the comparison between friction and frictionless mechanics showed no statistically significant changes.

A Novel Machine Learning Model for Predicting Orthodontic Treatment Duration.

In the field of orthodontics, providing patients with accurate treatment time estimates is of utmost importance. As orthodontic practices continue to evolve and embrace new advancements, incorporating machine learning (ML) methods becomes increasingly valuable in improving orthodontic diagnosis and treatment planning. This study aimed to develop a novel ML model capable of predicting the orthodontic treatment duration based on essential pre-treatment variables. Patients who completed comprehensive orthodontic treatment at the Indiana University School of Dentistry were included in this retrospective study. Fifty-seven pre-treatment variables were collected and used to train and test nine different ML models. The performance of each model was assessed using descriptive statistics, intraclass correlation coefficients, and one-way analysis of variance tests. Random Forest, Lasso, and Elastic Net were found to be the most accurate, with a mean absolute error of 7.27 months in predicting treatment duration. Extraction decision, COVID, intermaxillary relationship, lower incisor position, and additional appliances were identified as important predictors of treatment duration. Overall, this study demonstrates the potential of ML in predicting orthodontic treatment duration using pre-treatment variables.