Comparison of the impacts of two kinds of brackets on external apical root resorption in orthodontic treatment of bimaxillary protrusion patients / 中国组织工程研究

BACKGROUND: In orthodontic treatment, there will be different degrees of external apical resorption. Severe root resorption will reduce the root/shoot ratio, reduce the stability of teeth, and even cause teeth to loosen and fall out. OBJECTIVE: To compare the difference of external apical root resorption between high torque self-locking bracket and traditional straight wire bracket in orthodontic treatment of bimaxillary protrusion patients. METHODS: Forty-nine patients with bimaxillary protrusion, aged 13-16 years, who were treated in the Hospital of Stomatology of Southwest Medical University from January 2016 to December 2019, were enrolled in this study. The patients were divided into the high torque self-locking bracket group (n=24) and the traditional straight wire bracket group (n=25). Cone beam CT was taken before and after orthodontic treatment. The root morphology and length of maxillary central incisors and lateral incisors were observed by CS 3D Imaging Software. The amount of external apical root resorption between maxillary incisor and lateral incisor was calculated. This study was approved by the Medical Ethics Committee of Hospital of Stomatology of Southwest Medical University. RESULTS AND CONCLUSION: (1) The two groups after orthodontic treatment had achieved a good correction effect. The course of treatment was shorter in the high torque self-locking bracket group than that in the traditional straight wire bracket group (P 0.05). In the same appliance group, the amount of external apical root resorption of the maxillary central incisors was less than the lateral incisors (P < 0.05). (4) Results indicate that compared with the traditional straight wire bracket, the high torque self-locking bracket may have the advantages of short treatment course and low risk of apical absorption in the orthodontic treatment of bimaxillary protrusion.

Effect of double chain method on the closure of orthodontic teeth / 解剖学报

Objective To study the safety and effectiveness of the double chain method on the closure of the space of the teeth. Methods Totally 72 cases of different maxillary and mandible dentition space were included in the study. The pulp vitality was measured before and after treatment, the maxillary and mandible first molar teeth. All values were compared to assess the safety of dental pulp vitality. There were 36 cases in tooth extraction group and non-tooth extraction group.The observation period was 4 weeks, the changes of the alveolar space between maxillary and mandible teeth in adult and minor groups were measured before and after treatment. The difference of the total groove spacing before and after treatment were calculated and compared, to assess the effectiveness of space closure. Results In all 72 patients, there was no significant difference in the vitality of the pulp before and after treatment (P>0. 05). Compared to before treatment, the sum of the distance between the upper and lower mandibular groove using the double chain method was significantly reduced for both adult and juvenile patients in the four week tooth extraction group and the nontooth extraction group,the difference was statistically significant (P<0. 05). Conclusion Double chain closed teeth space does not cause pulp degeneration and necrosis. It is safe in clinical practice. Double chain method is effective, and can simplify the clinical operation.

Therapeutic effect analysis of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique / 华西口腔医学杂志

OBJECTIVE@#This study aimed to investigate the therapeutic effects and advantages of skeletal class Ⅲ malocclusion treatment by transmission straight wire technique.@*METHODS@#Ninety-seven patients who received treatment for skeletal class Ⅲ malocclusion at the Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2012 to January 2017 were selected for this retrospective study. All these patients refused surgery. They were divided into two groups in accordance with the type of skeletal malocclusion: mild-to-moderate skeletal malocclusion group (-4°≤ANB <0°) and severe skeletal malocclusion group (-8°≤ANB<-4°). Each of the two groups was divided further into two small groups in accordance with the technique used: T group (transmission straight wire technique) and M group (MBT technique).@*RESULTS@#The crossbite of all 59 patients in the mild-to-moderate skeletal malocclusion group was successfully treated. The molars were classified as classⅠrelationship, and the facial profile improved. Significant differences were found in the values of U1/SN angle, L1/MP angle, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05). In the severe skeletal malocclusion group, the crossbite of all 38 patients was cured or partially cured. Fourteen patients showed severe lower anterior teeth inclination (five in the T group and nine in the M group), and the profiles did not significantly improve. Significant differences were observed in the values of U1-NA value, U1/SN angle, L1-NB value, L1/MP angle, LLP, and Lip-Diff between the T and M groups before and after the treatment (P<0.05). The extent of incisor root resorption was lighter in the T group than in the M group (P<0.05).@*CONCLUSIONS@#Relative to the MBT technique, the transmission straight wire technique has great advantages in improving facial profile, reducing the compensatory inclination of the upper and lower anterior teeth, and reducing the risk of root resorption in the treatment of skeletal class Ⅲ malocclusion.

Tratamiento de maloclusión de clase III con arco multiloop edgewise arch wire (meaw) reporte de caso clínico / Treatment malocclusion class III with multiloop edgewise arch wire (meaw) case report

Resumen En la actualidad hay diferentes formas de abordar la maloclusión de clase III, todas las formas tienen como objetivo principal solucionar la maloclusión y están encaminadas a diagnosticar y llevar al paciente a una oclusión es table, estética y sobretodo sin daño alguno a los tejidos que conforman el sistema estomatognático. Se muestra en este artículo el manejo de la ma loclusión de clase III con arcos de Multiloop Edgewise Arch Wire (MEAW) como una opción rápida, estable y de excelentes resultados para la solu ción de este tipo de discrepancias. La maloclusión de clase III puede ser tra tada de diferentes formas como el tratamiento temprano, la compensación dental, el camuflaje esquelético y la opción quirúrgica. La compensación dental puede ser de diferentes formas, como por ejemplo: exodoncias de premolares inferiores, torque inferior negativo y positivo superior, con ayuda de anclaje esquelético (mini tornillos) y muchas más que no se enuncian. En los casos que se involucra el perfil o la simetría facial y su origen es de características de ADF (Anomalía Dentocranéo Maxilofacial) requirieran de cirugía ortognatica para su solución, puesto que es de origen esquelético y debido a severidad es no compensable. Este articulo muestra un manejo diferente como opción de compensación de maloclusión de clase III. Es un reporte de caso clínico de un paciente del Posgrado de Ortodoncia de la Universidad Antonio Nariño de la clínica de arco recto manejado con brac kets de prescripción MBT Gemini Unitek 3M slot 0.022"x0.025" los cua les se les coloca arcos de Multiloop Edgewise Arch Wire (MEAW) después de ocho meses de tratamiento, cuatro meses en alineación y nivelación y cuatro meses del uso arcos de Multiloop Edgewise Arch Wire (MEAW) la corrección dentoalveolar se corrige gracias a la retracción canina y molar de 6mm bilateral haciendo rotar el plano de oclusión según la filosofía del tratamiento de Multiloop Edgewise Arch Wire (MEAW) obteniendo las seis llaves de la oclusión de Andrews.

Abstract At present, there are different ways of approaching Class III malocclusion, all of which have the main objective of solving malocclusion and are aimed at diagnosing and bringing the patient to a stable, aesthetic occlusion and above all without any damage to the tissues that make up the Stomatognatic system. This paper deals with the handling of Class III malocclusion with Multiloop Edgewise Arch Wire (MEAW) as a fast, stable and excellent choice for solving this type of discrepancy. Class III malocclusion can be treated in different ways such as early treatment, den tal compensation, skeletal camouflage and surgical option. The dental compensation can be of different forms, as for example: extractions of lower premolars, negative inferior torque and superior positive, with the aid of skeletal anchorage (TAD) and many more that are not stated. In cases, involving facial profile or symmetry and its origin is the characteristics of ADF (Maxillofacial Dentocranial Anomaly) require orthognathic surgery for its solution, since it is of skeletal origin and due to severity is not compensable. This article shows a different management as an option for class III malocclusion compensation. It is a clinical case report of a patient of the Orthodontics Postgraduate of the Antonio Nariño University of the straight arch clinic handled with MBT Gemini Unitek 3M slot 0.022 "x0.025" brackets which are placed with Multiloop Edgewise Arch arcs Wire (MEAW) after eight months of treatment, four months in alignment and leveling, and four months of use Multiloop Edgewise Arch Wire (MEAW) correction is corrected by bilateral canine and molar retraction by rotating the plane Of occlusion according to the philosophy of the treatment of Mul tiloop Edgewise Arch Wire (MEAW) obtaining the six keys of the Andrews occlusion.

Evolución de pacientes adultos tratados con técnica de arco recto / Evolution of Adult Patients Treated with Straight Wire Technique

Introducción: la técnica de arco recto produce una revolución en la aparatología fija ortodóncica y su uso en pacientes adultos representa una herramienta para el especialista. Objetivo: describir la evolución de los pacientes adultos tratados con la técnica de arco recto después del tratamiento. Métodos: se realizó un estudio cuasi experimental, en el período de septiembre de 2014 a septiembre de 2015. El universo quedó constituido por 60 pacientes, en las edades de 19 a 59 años, que fueron atendidos en el Servicio de Ortodoncia de la Clínica Estomatológica Docente Mario Pozo. El examen y el estudio de los casos se realizó en el sillón dental con luz artificial por los autores de la investigación, utilizando set de clasificación, pie de rey, regla milimetrada, modelos de estudio, radiografías periapicales y panorámicas. Resultados: en los pacientes estudiados prevaleció la evolución favorable en el 88,33%, y de ellos, el sexo masculino con el 94,44%. El grupo de edad de 19 a 34 años predominó en el 95,34% de los casos y el tipo facial euriprosopo que representó el 100%. No hubo diferencias significativas en cuanto al estado del periodonto de inserción en los pacientes antes y después del tratamiento con esta técnica. Conclusiones: la mayoría de los pacientes adultos tratados con técnica de arco recto tuvieron una evolución favorable, sin alteraciones periodontales.

Introduction: the Straight Archwire Technique has caused a true revolution in fixed orthodontic appliances and its use in adults represents an important tool for the specialists. Objective: to describe the evolution of adult patients treated with straight wire technique after treatment. Method: a quasi-experimental study was conducted in the period from September 2014 to September 2015. It included 60 patients, aged 19-59 years, who were treated at Orthodontics Department of at the “Mario Pozo” Teaching Odontology Clinic. The examination and study of cases was performed in the dental chair with artificial light by the authors of the research, using a classification set, caliper, millimeter ruler, study models, and periapical and panoramic radiographs. Results: in the studied patients with positive developments prevailed 88.33%, specifically the age group of 19-34 years with 94.44% and the euriprosopic facial type with 100%. There were no significant differences in the condition of the insertion periodontium in patients before and after the Straight Archwire treatment. Conclusion: the majority of adult patients treated with the straight archwire technique showed a satisfactory progress without periodontal alterations.

Comparison between transmission technique and MBT straight wire technique in correction of protruding in adults / 中华医学美学美容杂志

Objective To evaluate the curative effect by using transmission straight wire appliance in treatment of adult patients with protruding,to compare with MBT straight wire technique,and to discuss their similarities and differences.Methods Totally 40 protruding patients were assigned into two groups randomly:the transmission straight wire technique group were treated with transmission straight wire appliance,and the MBT straight wire technique group were treated with MBT appliance together with extraoral arch or screw implant anchorage.Cephalometric measurements were compared before and after treatment.Results Average period of treatment was (19 ±4) months for transmission group and (23 ± 4) months for MBT group.The difference was statistically significant (P＜0.05).After treatment,U1/SN,U1/NA,U1-NA,L1/NB,L1-NB,U1-AP,L1-AP,UL-EP,LL-EP were significantly reduced for both patients groups (P＜0.01).U1/L1,nasolabial angle and z angle were increased for both groups (P＜0.05).MP/SN increased by 1.93°(P＜0.05)for transmission group vs.0.81° (P＞0.05) for MBT group.There was no statistically significant difference between the two groups (P＞0.05) except MP/SN (P＜0.05).However,the retraction of anterior teeth in transmission group was greater than that of MBT group,and U1/NA changed (-20.95±8.79)° in transmission group vs.(-16.00 ± 6.52)° in MBT group.Conclusions Both techniques can achieve satisfactory results for protruding cases.The transmission technology can improve soft tissue profile quicker,but anterior teeth have excessive vertical trend,where attention should be paid to control torque on anterior teeth.

Tratamento multidisciplinar visando a excelência: apresentação de um caso clínico / Multidisciplinary treatment aiming at excellence: a clinical case report

Resumo / Atualmente, quando os pacientes vêm ao nosso consultório, sabem exatamente o que querem e já vislumbram um resultado final próximo à excelência. Alinhamento e nivelamento é pouco. Hoje os pacientes almejam uma aparência próxima aos artistas do “Jet Set”, com dentes brancos e reluzentes. Assim, ao final do tratamento ortodôntico, uma finalização estética deve ser envolvida. Portanto, hoje, para se alcançar os resultados esperados, o tratamento multidisciplinar é imprescindível. O presente artigo aborda um tratamento restaurador total em um paciente adulto, sendo iniciado pelo tratamento ortodôntico e finalizado por reabilitação bucal total com prótese sobre implante e restauração tipo full veneer (FV). Esse tipo de técnica é usada em casos onde é possível cobrir todas as faces de um dente com o um mínimo de desgaste ou até sem preparo algum, mantendo a maior área possível em esmalte e preservando a estrutura dentária. O artigo evidencia a importância do tratamento ortodôntico prévio ao tratamento reabilitador para se alcançar resultados excelentes.

Evaluation on effectiveness of individual lingual orthodontics and labial straight wire orthodontics by X-ray cephalometrics / 吉林大学学报(医学版)

Objective To compare the X-ray cephalometric results of teeth and skeleton relationship between individual lingual orthodontic and labial straight wire orthodontics,and to provide reliable theoretical foundation for selecting orthodontic system in clinic. Methods The general conditions of the patients, classification of malocclusion,severity of denture crowding and orthodontic design were used as the selection criteria. Thirty familiar adult patients with malocclusion in clinic were divided into two groups randomly:individual lingual orthodontics group (A group)and labial straight wire orthodontics group (B group),15 cases in each group.X-ray cephalometrics were taken using Steiner and Tweed cephalometrics analysis,the results of analysis were compared between pre-treatment and post-treatment in two groups respectively, and the course of treatment in two groups was compared,too.The difference of treatment effect and course of treatment between two different orthodontic systems was evaluated.Results The relationship of first molar and canine of the patients in two groups was neutral relationship,overbite and overjet of anterior teeth was shallow,the teeth arrangement was orderly and no space was left after treatment.There was no statistically significant difference (P>0.05)between two groups in each measured values detected by Steiner Analysis after orthodontic treatment;there was no statistically significant difference (P>0.05)between two groups in each measured value detected by Tweed Analysis after orthodontic treatment;and there was no statistical significance (P>0.05 )in the D-values of Steiner Analysis and Tweed Analysis between two groups before and after treatment.The duration of treatment of the patients in two groups had no significant difference (P>0.05).Conclusion Both individual lingual orthodontics and labial straight wire orthodontics could obtain well teeth arrangement and occluding relationship and achieve satisfying clinical orthodontic outcome.

A clinical study on the effect of maxillary incisor torque with controlling root auxiliary arch / 实用口腔医学杂志

Objective:To explore the torque effect of controlling root auxiliary arch on the straight wire appliance on maxillary anterior teeth.Methods:22 patients with class Ⅱ1 extraction treatment,treated with straightwire appliance,at the detailing treatment stage were treated with controlling root auxiliary arch over the erect or introverted maxillary incisors for positive torque.The main arch wire of 0.46 mm ×0.64 mm stainless steel edge wire was used in 14 cases,the main arch wire of 0.46 mm stainless steel round wire was used in 8 cases.Cephalometric results before and after maxillary incisor torque were analyzed by t test.Results:After maxillary incisor torque in the 22 cases 1-SN and UIa-NA value increased(P ＜0.01),positive torque was achieved by controlling root auxiliary arch on the upper incisors;the round wire maxillary incisor torque worked faster than the edge wire(P ＜0.05).Conclusion:At the detailing stage of treatment straight wire appliance on front teeth,controlling root auxiliary arch is simple and effective in the treatment of exces-sive erect or lingual inclination of maxillary incisor.

Establishment of a three-dimensional finite element model of transmission straight wire appliance / 中国组织工程研究

BACKGROUND:With the development of modern orthodontics, to invent an efficient appliance is the focus in recent studies. Transmission straight wire appliance was born on this background. This appliance can accelerate occlusion and shorten treatment duration. The relationship between distal width and angulation of gable bends of main arch wire needs to study in depth. OBJECTIVE:To establish three-dimensional finite element model of transmission straight wire appliance with better biological and mechanical similarity, and to obtain the relationship between distal width and angulation of gable bend of main arch wire. METHODS:By using scanning of spiral CT with 64 rows, the sectional image data in DICOM format of maxil ary dentition and maxil ae of the volunteers (Class Ⅱ, division 1) were obtained. With the help of Ansys workbench 13.0, Mimics 10.01, Unigraphics NX and Geomagic Studio 8.0 softwares, the three-dimensional finite element model including transmission straight wire appliance, bend, Australian Orthodontic Wire, maxil ae, maxil ary tooth and periodontal ligament was established in Windows XP Service Pack 3 system. RESULTS AND CONCLUSION:A three-dimensional finite element model of transmission straight wire appliance was established, which consisted of 250 929 elements and 657 766 nodes. Furthermore, three-dimensional finite element model had higher geometric similarity and mechanical similarity, as wel as the advantages of adding or subtracting components according to the requirement of the research. The model was conductive to analyze the mechanical system of transmission straight wire appliance and guide the clinical application and appliance modification.

Ortodontia lingual: arco reto ou arco em forma de cogumelo? / Lingual Orthodontics: straight-wire or mushroom archwire?

A Ortodontial lingual aplica dois tipos de arco com mais frequência em sua técnica. Foi introduzido mais recentemente o arco reto lingual, depois de décadas utilizando o arco em forma de cogumelo. Alguns autores defendem o uso do arco reto por terem diversas vantagens em relação ao arco cogumelo. Porém, outros ainda persistem com o arco cogumelo como uma escolha ideal para a ortodontia lingual. Esse trabalho teve como objetivo levantar comparativamente e discutir algumas vantagens e desvantagens de ambas formas de arco. Pode-se concluir que há vantagens e desvantagens em cada tipo; o arco reto pode ser uma boa opção para o ortodontista que necessita facilitações práticas para exercer a técnica e o arco em forma de cogumelo pode ser mais confortável. O arco reto pode ser uma melhor opção quando se deseja melhor controle de torque na região anterior; o arco em forma de cogumelo pode ser uma melhor opção quando se deseja alinhamentos; e os procedimentos laboratoriais para a adoção do arco reto podem ser mais trabalhosos que o arco em forma de cogumelo.

There are two archwires commonly used for lingual orthodontics. The lingual straight-wire was recently introduced after decades using the mushroom archwire. Some authors defend the use of the straight-wire affirming it has several advantages over the mushroom archwire. However, several authors still persist with the mushroom archwire as an ideal choice for lingual orthodontics technique. This study aimed to discuss the advantages and disadvantages of both archwire types establishing a comparison between both of them. It was concluded that each one of them have its advantages and disadvantages. Straigh-wire can be a good option when a more precise control of torque in the anterior region is required. In the other hand the mushroom archwire can be more comfortable, and it can also be a better option when aiming to obtain alignments. Regarding the laboratory procedures the adoption of the straight-wire can be more laborious than the mushroom archwire.

Biomechanical modeling of dentulous mandible-straight wire appliance / 医用生物力学

Objective To establish the model of dentulous mandible and straight wire appliance and investigate the stress and displacement distributions of the roots and periodontal tissues under en masse space closure with sliding mechanics. Methods The three-dimensional finite element model of mandible and teeth was developed from CT images, which consisted of the dentin, enamel, dental pulp, PDL (periodontal ligament), cortical and cancellous bone. The models of Roth straight wire brackets with actual data were also constructed. The dental adhesives were used to stick the brackets on the corresponding teeth. Contact elements were used to simulate the interaction between the stainless steel arch wire and the brackets. Moreover, spring elements were used to connect the brackets and the arch wire. The load with the value of 1 N was applied on the model to close the space. Results The lingual tipping of lateral and central incisors was found, corresponding with the clinical observation of en masse space closure with sliding mechanics. High stress in the teeth and periodontal tissue appeared at the incisors and the distal roots of the first molars. The maximum von Mises stresses in PDL of the central incisors and the distal roots of the first molars were 3.97 kPa and 5.75 kPa, respectively. Conclusions In order to avoid root resorption of incisors, the torque of the brackets could be increased. Less orthodontic forces or orthodontic implant could be used to avoid distal roots of first molars.

O paradigma do protocolo de tratamento da sobre mordida profunda / The paradigm of deep bite treatment protocol

A sobremordida profunda presente na curva de Spee acentuada é uma característica comum nas maloclusões dento-esqueletais exigindo do profissional muita acuidade e intervenção precoce para se evitar que problemas funcionais e disfunções das articulações temporomandibulares sejam instalados, bem como, o restabelecimento da normalidade do crescimento mandibular. É largamente aceito pela comunidade ortodôntica, como meta de tratamento, a rotação horária da mandíbula no propósito de aumentar a altura facial inferior e, consequentemente, corrigir a sobremordida profunda. Assim, esse protocolo, passa a ser o grande paradigma, pois este trabalho tem como proposta elucidar que a rotação anti-horária da mandíbula deve ser considerada quando estamos diante de um paciente adulto com sobremordida profunda e disfunção articular.

The deep bite present in the Spee accentuated curve is a common characteristic in the dentoskeletal malocclusions demanding from the professional very criterion and earlyintervention to avoid that functional problems and TMJ dysfunctions are installed, as well as, the reestablishment of the mandible growth normality. It is widely accepted by the orthodontics community, as the treatment goals, the mandible clockwise rotation in thepurpose of the increase the lower face height and consequently, to correct the deep bite. And this protocol, passes the being the great (or and this protocol become the great) paradigm, because this work has a proposal to elucidate that the mandible counterclockwise rotation should be considered when we are before an adult patient with deep bite and TMJ dysfunction.

Effects of lingual orthodontics on function and aesthetics of stomatognathic system / 中华医学美学美容杂志

Objective To evaluate the functional and aesthetic disturbance of patients treated with lingual orthodontic surgery and to investigate the key points of laboratory procedure and clinical treatment of lingual orthodontic deformity. Methods A total of 30 cases of Angle class Ⅰ with moder-ate crowding were selected. They were equally divided into two groups: one group was treated using lingual brackets, and the other using conventional labial brackets. Each patient completed a four-part survey right after the bracket placing and 7, 28, 56 days after the treatment. The differences of tongue-lip-cheek soreness, eating and speech difficulties and aesthetic problems were evaluated be-tween two groups. Lateral cephalograms were analyzed at the start of the treatment and the end of the overall treatment. Results Speech difficulties of lingual orthodontics were significantly greater (P<0.01) than that in the labial orthodontics group in the first week of the treatment. Eating difficulties were greater (P<0.01) in the lingual orthodontics group by 28 days, whereas aesthetic problems were greater in group using labial appliance than group lingual appliance. Conclusions In the first two months of the orthodontic treatment, eating and speech difficulties are the most severe problems for the lingual group. Lingual orthodontics offers important aesthetic advantages over labial orthodontics, and it will be one of the development directions of current orthodontics.

Labial and buccal surface contours of Korean normal occlusion in a three-dimensional digital model / 대한치과교정학회지

OBJECTVIE: This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth and to obtain the curve-ratio data in an attempt to fabricate bracket bases fit for each individual Korean permanent tooth. METHODS: Three-dimensional digital models were made from 30 sets of dental casts with normal anatomic structures. According to the FA points, horizontal and vertical reference planes were established and lines were drawn on the tooth surfaces in reference to these planes. The curvature was expressed as the coefficient of a quadratic equation. Lines mesial, distal, gingival and occlusal to the horizontal, vertical reference planes and the FA point were drawn. RESULTS: The curvature measured for each line revealed that there are no significant differences between male and female, except for maxillary canines and maxillary second bicuspids (p > 0.05). There were notable differences in the mesio-distal or gingivo-occlusal curvatures among the mandibular lateral incisors, maxillary canines, maxillary and mandibular first and second bicuspids and first molars (p < 0.05). CONCLUSIONS: The labial & buccal crown curvatures of teeth in Korean normal occlusion were measured on the mesial and distal, gingival and occlusal sides respectively in this study. Based on these data, a SWA can be developed to fit the individual features of Korean tooth crowns.

Transmission straight wire appliance treats Angle Ⅱ 1 malocclusion:report of 13 cases / 第三军医大学学报

Objective To observe the clinical effects of transmission straight wire appliance on the treatment of AngleⅡ1 malocclusion and explore its mechanism.Methods Thirteen AngleⅡ1 malocclusion patients (6 males and 7 females) were treated with the appliance by extracting 4 first premolars or 2 first maxillary premolars.The results of cephalometric measurements before and after treatment were statistically analyzed.Results The average treatment time of 13 cases was 15.6 months.The overbite's treatment cost 4.2 months averagely.Overbite,overjet and molar relationship were turned to normal (only one adult case had complete distal in the molar relationship by extracting 2 first maxillary premolar) and lateral appearances were improved after treatment.The results of cephalometric analysis showed that the changes of SNB,ANB,U1-NA angle,L1-NB angle,U1-LI angle,U1-NA length,L1-NB length,L6-MP length,L1C-MP length,overbite,and overjet were of high statistical significance (P0.05).Conclusion Transmission straight wire appliance can quickly and efficiently correct AngleⅡ1 malocclusion.

A study for the development of the Korean orthodontic bracket / 대한치과교정학회지

The aim of this study was development of the Straight-Wire Appliance(SWA) suitable for the treatment of Korean. To accomplish the object of this study, Korean adult with normal occlusion were selected with following criteria: 1) no functional abnormality in the craniofacial area, 2) good dental arch form and posterior occlusal relationship, 3) Angle Class I occlusal relationship, 4) no experience of orthodontic, nor prosthodontic treatment, especially, no dental treatment on labial and buccal surfaces of teeth, 5) good facial profile. Impression were taken for upper and lower dental arches of the selected normal occlusion samples and the orthodontic dental stone models were fabricated. 5 well-trained orthodontists had examined the acquired dental stone models to select study samples which satisfy the Six keys to optimal occlusion of Andrews. 155 pairs of dental stone models (92 pairs of Male, 63 of Female) were finally selected. 3 dimensional digitization were performed with the Coordinate Measuring Machine(CMM, MPC802, WEGU-Messtechnik, Germany) and measuring of Angulation, Inclination, In-and-Out, Molar offset angle and Arch form were accomplished with a measuring software to achieve data for the development of SWA. Before the measurement, error study was performed on the 3 dimensional digitization with CMM, and the analysis of reliability of computerized measuring method adapted in this study and conventional manual method presented by Andrews was performed. Results of this study were as follows: 1. Equi-distance digitization with mesh size 0.25 mm, 0.5 mm and 1.0 mm were acceptable in 3 dimensional digitization of dental stone model with the CMM, and the digitization with 1.0 mm mesh size was recommendable in terms of efficiency. 2. Computerized measuring method with 3 dimensional digitization was more reliable than manual measuring method of Andrews. 3. Data were collected for the development of SWA suitable for the morphological characteristics of Korean with the computerized measuring method with 3 dimensional digitization.

Crown angulations of posterior teeth of normal occlusion measured from marginal ridge plane / 대한치과교정학회지

In the previous studies about prescription of preadjusted appliance, occlusal plane was used as a reference plane for crwon angulation (tip) measurement But this reference plane is not parallel to the he connecting the facial axis points at which the centers of brackets are positioned (Andrews' plane), due to the curve of Spee. Therefore, we developed a new reference plane unaffected by the curve of Spee and more parallel to the Andrews' plane. It is an imaginary line connecting mesial and distal marginal ridges of each posterior tooth, and we named it 'marginal ridge plane'. In this study, crown angulations of posterior teeth of 29 normal occlusion samples were measured and measurements from both reference planes were compared. Crown angulation measurements measured from occlusal plane were different from crown angulation measurements from marginal ridge plane in the upper and lower 2nd molars (p<0.01), and 1st premolars (p<0.05). These results were analyzed as the crown angulation measurements from occlusal plane were affected by the curve of Spee. Crown angulations should be vaned according to the amount of curve of Spee to maintain- the continuity of marginal ridges. To solve this problem, determining bracket angulation as the bracket slot is parallel to the marginal ridge plane of each posterior teeth is recommended.

Clinical consideration on using the elastic "tie backs" during space closure / 대한치과교정학회지

Preadjusted appliance, following the original concept of the Andrews Straight-Wire appliance, became increasingly common in the 1980s. In six phases of treatment, anchorage control, leveling and aligning, overbite control, overjet reduction, space closure, and finishing are very effective with using the preadjusted appliances. Space closure is the phase of treatment in which the difference between standard edgewise and preadjusted mechanics is most noticeable. Orthodontists have been able to reduce the use of closing loops and, because of the level slot lineup, enjoy the advantages of sliding mechanics. In 1990, Dr. John C. Bennett and Richard P. McLaughlin introduced the new space closure system, namely, elastic "tiebacks". They found an .019"X.025" working archwire most effective in an .022"-slot system. Hooks of .024" stainless steel or .028" brass wire are soldered to the upper and lower archwires. The force required for space closure is delivered by elastic "tiebacks". An elastic module stretched by 2-3mm(to twice its normal length) usually delivers 0.5-1.5mm of space closure per month. Group movement and sliding mechanics are combined for gentle, controlled space closure, so that about 0.5mm of incisor retraction and 0.5mm of mesial molar movement can be seen each month. The tiebacks are replaced every four to six weeks. By using the elastic "tiebacks", the next two cases were treated during space closure. Even though we found some clinical problems of this mechanics, long treatment time, hard to control of vertical dimension and anchorage, the application method of this system is so simple that orthodontists can manage many patients during short chair time. But we must apply this mechanics after perfect understanding of the biomechanics in tooth movement.