Factors related to the control of maxillary anterior teeth torque in invisible appliances / 口腔疾病防治

@#Invisible appliance technology is a novel orthodontic technology that uses computer aided design and polymer materials to achieve a more aesthetic and comfortable treatment. Compared with traditional lip-bracket orthodontic treatments, the greatest advantages of an invisible appliance are aesthetics. In the orthodontic process, the control of the anterior teeth may not be accurate, which often directly affects the patient′s postoperative side appearance; however, in clinical practice, there is still a large deficiency in the control of the anterior tooth torque by an invisible appliance compared to traditional lip-bracket orthodontic treatments. The factors related to the expression efficiency of anterior tooth torque include the combination of morphology and position of different types of brackets and wires, the tooth movement mode and clincheck design. This article reviews the factors that influence lingual orthodontics and clear aligner therapy in the treatment of anterior tooth torque.

Evaluation of changes in the maxillary alveolar bone after incisor intrusion / 대한치과교정학회지

OBJECTIVE: This study was performed to investigate the changes in alveolar bone after maxillary incisor intrusion and to determine the related factors in deep-bite patients. METHODS: Fifty maxillary central incisors of 25 patients were evaluated retrospectively. The maxillary incisors in Group I (12 patients; mean age, 16.51 ± 1.32 years) were intruded with a base-arch, while those in Group II (13 patients; mean age, 17.47 ± 2.71 years) were intruded with miniscrews. Changes in the alveolar envelope were assessed using pre-intrusion and post-intrusion cone-beam computed tomography images. Labial, palatal, and total bone thicknesses were evaluated at the crestal (3 mm), midroot (6 mm), and apical (9 mm) levels. Buccal and palatal alveolar crestal height, buccal bone height, and the prevalence of dehiscence were evaluated. Two-way repeated measure ANOVA was used to determine the significance of the changes. Pearson's correlation coefficient analysis was performed to assess the relationship between dental and alveolar bone measurement changes. RESULTS: Upper incisor inclination and intrusion changes were significantly greater in Group II than in Group I. With treatment, the alveolar bone thickness at the labial bone thickness (LBT, 3 and 6 mm) decreased significantly in Group II (p < 0.001) as compared to Group I. The LBT change at 3 mm was strongly and positively correlated with the amount of upper incisor intrusion (r = 0.539; p = 0.005). CONCLUSIONS: Change in the labial inclination and the amount of intrusion should be considered during upper incisor intrusion, as these factors increase the risk of alveolar bone loss.

Orthodontic treatment with maxillary incisor extraction / 实用口腔医学杂志

Objective:To evaluate the effectiveness and treatment feature of maxillary incisor extraction in orthodontics.Methods:9 patients underwent orthodontic treatment with maxillary incisor extraction,5 female and 4 male,with an average age of 1 7.2 years at the start,were included.5 patients were treated by extraction of both upper incisors and lower first premolars,4 by extraction of the abnor-mal incisor and the first premolars in the other three quadrants.Cephalometric and Bolton index analysis were carried out.Results:Sat-isfactory treatment results were observed in all patients.Before treatment the predicted Bolton index of the patients of the anterior ratio and the overall ratio were 80.1 4% and 91 .3%,after orthodontic treatment 78.68% and 90.28%,respectively.Cephalometric analysis showed that U1 -NA(mm),U1 -NA,L1 -NB(mm),L1 -NB,U1 -SN,L1 -MP,UL-E and LL-E were decreased(P <0.05).Conclu-sion:Individual treatment plan based on Bolton index analysis and the corresponding techniques and methods,the patients with abnor-mal upper incisors can be effectively treated with the extraction of maxillary incisors.

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.

A rare case of dilated invaginated odontome with talon cusp in a permanent maxillary central incisor diagnosed by cone beam computed tomography

It has been a challenge to establish the accurate diagnosis of developmental tooth anomalies based on periapical radiographs. Recently, three-dimensional imaging by cone beam computed tomography has provided useful information to investigate the complex anatomy of and establish the proper management for tooth anomalies. The most severe variant of dens invaginatus, known as dilated odontome, is a rare occurrence, and the cone beam computed tomographic findings of this anomaly have never been reported for an erupted permanent maxillary central incisor. The occurrence of talon cusp occurring along with dens invaginatus is also unusual. The aim of this report was to show the importance of cone beam computed tomography in contributing to the accurate diagnosis and evaluation of the complex anatomy of this rare anomaly.

Carga imediata em região anterior com utilização da coroa clínica do dente natural perdido: relato de caso / Immediate loading in anterior region using the clinical crown of the lost natural tooth: a case report

Atualmente, um dos grandes desafios da Odontologia está relacionado à reabilitação bucal de pacientes que sofreram perdas dentárias por trauma, em especial nos elementos anterossuperiores. Nessas situações, os resultados estéticos e funcionais, associados à manutenção da saúde periodontal, são primordiais para a obtenção do sucesso e para o estabelecimento de um prognóstico adequado. Para essas situações dispomos da Implantodontia, que possibilita restituições dentárias por meio da inserção de implantes osseointegráveis suportando próteses aparafusadas ou cimentadas em substituição aos elementos perdidos. Uma etapa de provisionalização bem executada possibilita a manutenção dos tecidos gengivais em uma arquitetura harmoniosa, favorecendo o resultado final do tratamento como um todo. O presente artigo visa apresentar um caso clínico de fratura radicular de incisivo central superior direito (11) por traumatismo dentário, no qual se realizou a exodontia desse elemento, a inserção de implante imediato e a provisionalização subsequente com a coroa clínica do dente natural fraturado. Assim, verifica-se que a utilização da coroa do dente fraturado na confecção do provisório é uma técnica plausível quando se necessita não apenas de um resultado estético adequado, mas função imediata e, principalmente, manutenção da harmonia gengival e dentária.

One of the major current challenges in Dentistry is oral rehabilitation after tooth loss due to trauma. Esthetic and functional results, together with periodontal health, define success and prognosis. Implant dentistry provides the resources for the placement of osseointegrated screw-retained implants or cemented prostheses to replace missing teeth. Carefuluse of provisional prostheses preserves the harmonious architecture of gingival tissues and affects final treatmentresults positively. This study describes a clinical case of root fracture of the right maxillary central incisor (tooth # 11)due to dental trauma. The tooth was extracted, an immediate implant was placed and the provisional prosthesis was fabricated using the clinical crown of the fractured tooth. The use of a fractured tooth for provisional restorations is a viable technique that has good esthetic and functional results and preserves gingival and dental balance.

Inclinación de incisivos: cálculo de la cantidad de desplazamiento bucolingual y sus efectos en la longitud del arco dental / Incisor inclination: estimate of the quantity of bucolingual displacement and their effects on the dental arc lenght

Se presentan métodos para calcular con mayor precisión la cantidad de desplazamiento incisal en los movimientos de inclinación bucolingual, basados en las fórmulas longitud de arco y longitud de cuerda de una circunferencia y la ley del senocon centro de rotación dinámico. Cuando se usan arcos preformados de alambre durante las fases de alineación ortodóncica, la inclinación producida sobre los dientes anteriores afecta la forma y la longitud del arco total. Actualmente, esto es un aspectopoco evaluado. Se ofrecen guías para calcular estas variaciones con el propósito de lograr análisis de espacio más exactos. Representaciones y análisis de casos refuerzan esta propuesta.

Methods are presented to calculate more precisely the quantity of incisor displacement during buccolingual inclination movements. It is based on the arc length and chord length of a circle and law of sines with dynamic rotation center formulas. When preformed archwires are used during the orthodontic alignment phases, the inclination taking place on the anterior teeth affects the form and total arch length. At present this aspect has not been evaluated in depth. Guidelines are offered to calculate these variations with the purpose of achieving a more exact space analysis. Representations and case analysis reinforce this proposal.

Three-dimensional finite element analysis on the effect of maxillary incisor torque / 대한치과교정학회지

The purpose of this study was to investigate the stress distribution in the periodontal tissue and the displacement of teeth when active torque was applied to the maxillary incisors by three-dimensional finite element analysis. A three-dimensional finite element model consisted of the maxillary teeth and surrounding periodontal membrane, .022 x .028 Roth prescription bracket and stainless steel, NiTi and TMA rectangular ideal arch wires which were modeled by hexahedron elements. Applied active torques were 2, 5 and 10 degrees. The findings of this study showed that the reaction force acting on the bracket was the extrusion force on the mesial side of the incisors and canine and the intrusion force on the distal side of the incisors and canine. The amount of force and moment was greatest at the lateral incisor. When active anterior labial crown torque was applied, labial crown and distal tipping and intrusion of the incisors took place, and lingual crown distal tipping and extrusion of the canine occured. An excessive force was concentrated on the lateral incisor, when the stainless steel wire was used. NiTi or TMA wire is desirable for torque control.

The relationship between facialasymmetry and maxillary dental arch shape / 대한치과교정학회지

This study was designed to examine the dental asymmetry in person with facial asymmetry and to examine the relationship between the degree of mandibular deviation and asymmetry of maxillary dental arch. The samples were divided to asymmetry group and normal group. The asymmetry group consisted of 21 subjects(6 males and 15 females) and their mean age was 23.5 years. The normal group consisted of 20 subjects(10 males and 10 females) and their mean age was 18.6 Years. Anteroposterior, transverse position of all maxillary teeth except 3rd molars, vertical position of maxillary Ist molars, and angulation of central incisors were measured. The anterivposterior and transverse positions of teeth were measured on the maxillary dental casts, the vertical position of maxillary 1st molars and angulation of maxillary incisors were measured on posteroanterior cephalometiic radiographs. The data were analyzed to examine whether significant asymmetries existed in each of the asymmetry and normal groups. The results of this study were as follows : 1. In the asymmetry group, the correlation between the degree of mandibular deviation and that of 3-dimensional dental asymmetry was not so high. 2. In the asymmetry group, the teeth in deviated side were more laterally positioned than that of undeviated side. There were differences in the anteroposterior position of maxillary 1st and 2nd molars and the angulation of maxillary central incisors. 3. In the asymmetry group, the transverse asymmetry was larger in the posterior teeth rather than in the anterior teeth and larger than the anteroposterior asymmetry.

A study on the pattern of the root resorption following maxillary incisor retraction / 대한치과교정학회지

This study was carried out in order to find out the pattern of the root resorption following maxillary incisor retraction after maxillary 1st bicuspid extration in maxillary protrusion patients. For this study, thirty two patient who received orthodontic treatment were chosen. The results were as follows; 1. Of the total 192 teeth, 61 teeth(31.77%) showed no apical root loss, 64 teeth(33.33%) fell into the class "slight", 46 teeth(23.96%) fell into the class "moderate". Only 21 teeth(10.94%) were classified as "excessive". 2. No correlation was noted between the amount of apical root loss and the types of tooth movement of the maxillary central incisors. 3. The patients who were treated with standard brackets had more changes in tooth axis and less movement of root apexes, but the patients with straight brackets had less changes in tooth axis and more movement of root apexes. 4. Comparing the degree of root resorption between bracket types, patients who had used standard brackets showed more apical root loss than patients who had used straight brackets. 5. The most frequent degree of root resorption observed in standard bracket patients was second degree, followed by first degree and third degree. The most frequent degree of root resorption observed in straight bracket patients was zero degree, followed by first, second degree and third degree.