Desplazamiento de Tercer Molar Inferior a Espacio Submandibular: Reporte de Caso y Revisión de Literatura / Lower Third Molar Displacement to Submandibular Space: Case Report and Literature Review

El desplazamiento de un tercer molar a un espacio anatómico adyacente, ya sea en su totalidad o un fragmento de este, se encuentra descrito como una complicación rara pero posible de las exodoncias de terceros molares. En este reporte se aborda específicamente el desplazamiento accidental de un tercer molar inferior hacia el espacio submandibular izquierdo, el cual fue resuelto quirúrgicamente mediante un abordaje intraoral bajo anestesia general por el equipo de cirugía maxilofacial del Hospital de Urgencia Asistencia Pública, Santiago, Chile. Se realizó una revisión de literatura en la plataforma PubMed con las palabras claves "third molar - submandibular - displacement" obteniendo un total de 17 artículos en los cuales se reportan 15 casos. El propósito del presente escrito fue presentar recomendaciones sobre el manejo actual de esta complicación en base a la literatura disponible.

The displacement of a third molar into an adjacent anatomical space, either in its entirety or a fragment of it, has been described as a rare but posible complication of third molar extractions. This report will specifically address the accidental displacement of a lower third molar into the left submandibular space, which was surgically removed through an intraoral approach under general anesthesia, by the maxillofacial surgeon team of "Hospital de Urgencia Asistencia Pública", Santiago, Chile. An literature review was carried out on PubMed platform with the keywords ""third molar - submandibular - displacement"", obtaining a total of 17 articles where are reported 15 cases. The purpose of this paper is to present recommendations on the current management of this complication based on the available literature.

Influence of different orientations and rates of bidirectional distraction osteogenesis of the mandibular corpus: a three-dimensional study

Objective: The objective of this study was to evaluate the biomechanical effect of mandibular corpus distraction osteogenesis with different orientations and rates. Materials and Methods: A three-dimensional model of the mandible was created. The vertical surgical cut was made, the force was applied horizontally in a bidirectional manner within two orientations: parallel to the occlusal plane and parallel to the inferior border of the mandible with three rates (0.5mm, 1mm and 1.5mm). Results: The maximum values for von Mises stress when the force was applied parallel to the inferior border of the mandible with all three rates were smaller than those with force direction parallel to the occlusal plane. The displacement in all three directions x, y, and z were not parallel and prominent in the anterior part of the mandible, while the movement at the posterior part is negligible, x and z displacement were bigger when force was applied parallel to the inferior border of the mandible, z displacement was more prominent than x and y displacement, both directions produced upward rotation of the mandible, this rotation was more noticeable when the force was applied parallel to the inferior border of the mandible. Conclusions: A vertical cut can be used in the patient with a long anterior face. This site of distraction achieves more lengthening of mandible than expansion.

Intrusion of the extruded maxillary central incisor using skeletal anchorage system and unilateral segmental intrusion arch

Patients who have a moderate periodontitis with pathologic tooth migration of maxillary incisors, it is necessary not only periodontal treatment for reduce periodontal inflammation, but also orthodontic treatment to teeth repositioning. For orthodontic treatment, it is necessary to apply less force and careful considerations of the center of resistance of the tooth and optimal force of tooth movement. At this time, the segmental arch applied only to the target teeth, is more effective and predictable, because applied force and direction can be controlled. In addition, to design the orthodontic appliance that can prevent the unwanted tooth movement that used as an anchorage is important. In recent years, various types of skeletal anchorage system have been used for preventing loss of the anchorage. We reported the patient who had extruded maxillary central incisor due to pathologic tooth migration, treated by a successful periodontal-orthodontic multidisciplinary treatment using an orthodontic appliance designed to apply less traumatic force and reduce an anchorage loss.

Transmigrated canines associated to odontomas / Caninos transmigrados asociados a odontomas

We present the case of a 13-year-old patient with bilateral transmigration of mandibular canine associated with multiple composite odontoma. Impacted canines are very uncommon, with a 0.1 % to 3.6 % prevalence of appearance. The presence in the mandible is less frequent. The odontoma development is often associated with the impacted canines. The etiology is unknown but is associated with traumatic, infectious, hereditary or genetic factors. This pathology is asymptomatic and associated with eruption disorders in temporal and permanent dentition.

Presentamos el caso de un paciente de 13 años de edad con trasmigración bilateral de canino mandibular asociado a múltiples odontomas compuestos. Los caninos impactados son muy poco frecuentes, con una prevalencia de aparición de 0,1 % a 3,6 %. La presencia en la mandíbula es menos frecuente. El desarrollo de odontomas se asocia a menudo con los caninos impactados. La etiología es desconocida pero está asociada con factores traumáticos, infecciosos, hereditarios o genéticos. Esta patología es asintomática y está asociada a trastornos de erupción en dentición temporal y permanente.

Transmigrant impacted mandibular canine: a case report / Transmigração de canino impactado em mandíbula: relato de caso

Transmigration of canines across mandibular midline is a rare and elusive phenomenon described in the dental literature. Etiology of this phenomenon is obscure, but in some cases supernumerary teeth may be one of the causes. Surgical extraction is indicated due to pathologic lesions, infection, trauma to the adjacent teeth, pain, ectopic eruption and interference with prosthesis they may cause. The aim of this paper is to describe the treatment of a transmigrant impacted mandibular canine near the inferior border and to review the literature about its incidence, prevalence and treatment options. Vestibular access in the anterior mandible was performed followed by osteotomy and odontosection, for tooth removal. Canine impaction is more prevalent in the maxilla than in the mandible, but canine transmigration is more frequent in the mandible. Females seem to be more affected than males, with the left side being more prevalent than the right. Although the literature is controversial about treatment protocol for transmigrant teeth several authors indicate its extraction to prevent lesions that are associated with impacted teeth, specially when orthodontic traction is contraindicated due to the position of those dental units. (AU)

Transmigração de caninos através da linha mediana mandibular é um fenômeno raro descrito na literatura odontológica. A etiologia deste fenômeno é obscura, mas em alguns casos os dentes supranumerários podem ser uma das possíveis causas. A extração cirúrgica é indicada devido a lesões patológicas, infecção, trauma aos dentes adjacentes, dor, erupção ectópica e possível interferência ao uso de próteses que possam causar. O objetivo deste trabalho é descrever o tratamento de um canino mandibular transmigrado perto da borda inferior e analisar a literatura sobre sua incidência, prevalência e opções trapêuticas. Acesso vestibular na mandíbula anterior foi realizado seguido de osteotomia e odontosecção, para remoção do dente. A impactação canina é mais prevalente na maxila do que na mandíbula, mas a transmigração canina é mais freqüente na mandíbula. Mulheres parecem ser mais afetadas do que os homens, com o lado esquerdo sendo mais prevalente do que o direito. Embora a literatura seja controversa quanto ao protocolo de tratamento para dentes transmigrados, vários autores indicam sua extração para prevenir lesões associadas aos dentes impactados, especialmente quando o tracionamento ortodôntica é contra-indicado devido à posição dessas unidades dentárias.(AU)

A Ortodontia como adjunto no tratamento periodontal / The orthodontic movementation as an adjunctive to periodontal treatment

O tratamento ortodôntico em adultos com o periodonto reduzido tem exigido uma cooperação interdisciplinar, objetivando transformar pacientes que apresentam espaços interdentais esteticamente não atraentes, extrusões, ou ainda migração dentária patológica, em pessoas com dentições esteticamente melhoradas e função mastigatória restabelecida. O tratamento do paciente com alterações periodontais pode ser afetado pela Ortodontia de maneira positiva através de uma correta indicação, planejamento e execução conjunta das terapias periodontal e ortodôntica. Este trabalho se propôs a revisar a literatura sobre a inter-relação entre a Ortodontia e a Periodontia, apresentando um caso clínico no qual as terapias conjuntas foram essenciais para o estabelecimento da harmonia entre função mastigatória e estética dentogengival.

The orthodontic treatment for adults with reduced periodontium needs a multidisciplinary action, transforming patients with non-attractive interdental spaces, extrusions, or pathologic migrations into esthetically improved dentitions and still retrieving the masticatory function. There is a positive effect of orthodontic treatment for patients with periodontal problems when correct indication, planning, and execution are made. This paper revises the literature regarding the ortho-perio relationship, presenting a clinical case where both therapies were essential to reestablish harmony and function for dentogingival esthetics.

Orthodontic decompensation in skeletal Class III malocclusion: redefining the amount of movement assessed by Cone-Beam Computed Tomography

Introduction:Cone-Beam Computed Tomography (CBCT) is essential for tridimensional planning of orthognathic surgery, as it allows visualization and evaluation of bone structures and mineralized tissues. Tomographic slices allow evaluation of tooth inclination and individualization of movement performed during preoperative decompensation. The aim of this paper was to assess maxillary and mandibular incisors inclination pre and post orthodontic decompensation in skeletal Class III malocclusion.Methods:The study was conducted on six individuals with skeletal Class III malocclusion, surgically treated, who had Cone-Beam Computed Tomographic scans obtained before and after orthodontic decompensation. On multiplanar reconstruction view, tomographic slices (axial, coronal and sagittal) were obtained on the long axis of each incisor. The sagittal slice was used for measurement taking, whereas the references used to assess tooth inclination were the long axis of maxillary teeth in relation to the palatal plane and the long axis of mandibular teeth in relation to the mandibular plane.Results:There was significant variation in the inclination of incisors before and after orthodontic decompensation. This change was of greater magnitude in the mandibular arch, evidencing that natural compensation is more effective in this arch, thereby requiring more intensive decompensation.Conclusion:When routinely performed, the protocols of decompensation treatment in surgical individuals often result in intensive movements, which should be reevaluated, since the extent of movement predisposes to reduction in bone attachment levels and root length.

Introdução: a tomografia computadorizada de feixe cônico (TCFC) é essencial para o planejamento tridimensional de cirurgias ortognáticas, pois permite a visualização e avaliação de estruturas ósseas e tecidos mineralizados. Os cortes tomográficos permitem avaliar a inclinação dos dentes e individualizar o movimento realizado durante a descompensação dentária.Objetivo: o objetivo do presente estudo foi avaliar a inclinação dos incisivos superiores e inferiores antes e depois da descompensação ortodôntica da má oclusão de Classe III esquelética.Métodos:o estudo foi realizado em seis indivíduos com má oclusão de Classe III esquelética que passaram por tratamento cirúrgico e apresentaram exames de TCFC feitos antes e depois da descompensação ortodôntica. A reconstrução multiplanar foi feita a partir dos cortes tomográficos (axial, coronal e sagital) adquiridos no eixo longitudinal de cada incisivo. O corte sagital foi usado para a realização de medições, e as referências usadas para avaliar a inclinação dentária foram o eixo longitudinal dos dentes superiores em relação ao plano palatino e o eixo longitudinal dos dentes inferiores em relação ao plano mandibular.Resultados:houve uma variação significativa entre a inclinação dos incisivos antes e depois da descompensação ortodôntica. A alteração foi maior na arcada inferior, evidenciando que a compensação natural é mais efetiva nessa arcada, o que exige uma descompensação mais extensa.Conclusão:quando realizados rotineiramente, os protocolos de tratamento para descompensação em pacientes cirúrgicos geralmente resultam em movimentação extensa, que deve ser reavaliada, já que a extensão do movimento predispõe à perda de inserção e à redução do comprimento da raiz.

The effect of simvastatin on relapse of tooth movement and bone mineral density in rats measured by a new method using microtomography

PURPOSE: To evaluate the effect of simvastatin on relapse of tooth movement in rats using microtomography (micro CT), as well as the correlation of bone density with the orthodontic relapse. METHODS: Twenty-five adult male Wistar rats, divided into two groups, had stainless steel springs installed on left maxillary first molar. The molars were moved for 18 days, and after removing the springs, were applied by oral gavage, 5mg/kg of simvastatin in the experimental group for 20 days. Tooth relapse was assessed with a micro CT scanner, and the images chosen through the Data Viewer software 1.5.0.0 had their measurement guides made and checked by the software Image ProR plus 5.1, and compared by Mann-Whitney test. After rats were sacrificed, bone mineral density was evaluated by micro CT through the software CT Analyzer 1.13 and compared by independent T-test, as well as by Spearman correlation test. RESULTS: Relapse and bone mineral density (BMD) was lower in the experimental group than in the control group, however without a statistically significant difference. CONCLUSION: Simvastatin did not inhibit the relapse of tooth movement in rats, and there was no correlation between bone density and orthodontic relapse. .

Importancia del primer molar permanente y consecuencias clínicas de su pérdida en edades tempranas del desarrollo / Importance of the first permanent molar and clinical consequences of its loss at early developmental stages

El primer molar permanente es la undiad más importante de la masticación y es esencial en el desarrollo de una oclusión funcionalmente deseable. La pérdida de este molar en un niño puede conducir a cambios en las arcadas dentarias que se perpetúan a lo largo del tiempo. Si no se toman medidas preventivas o correctivas apropiadas, podrán encontrarse: disminución en la función local, desviaciones de las piezas dentarias, extrusión de la pieza antagonista y trastornos de las articulaciones temporomandibulares, entre otras alteraciones. El presente artículo pretende evidenciar el protagonismo del primer molar permanente en la cavidad bucal y las consecuencias negativas que derivan de su ausencia. Además, deja entrever las necesidades de conocimiento por parte del odontólogo en los cuidados preventivos de dichas piezas dentarias y sobre la existencia de posibles tratamientos al momento de una pérdida inminente.

Transmigration of the Mandibular Canine: A Report of Two Rare Cases.

When the tooth, instead of erupting in its normal position, remains impacted and crosses midline and is seen on the opposite side of the jaw, it is termed as Transmigration; e.g., right side tooth is seen on the left side and vice-versa. This phenomenon occurs without any pathology intervening cause. Canines are commonly seen unerupted and remain impacted, but rarely seen crossing the midline and migrating to the opposite side. They are usually symptomless. Here, we present two such rare cases of transmigration of the mandibular canine, one from the right side to the left side and appearing piercing the lower border of the mandible and producing a hard bulge on the left side of the lower jaw, but without any pain. The other case is of transmigration of mandibular left canine toward the right side well below the inferior alveolar canal beyond mental foramen facing toward posterior region of the mandible and causing pain symptoms in the jaw due to its close proximity to inferior alveolar canal. It is very essential to have panoramic radiograph to detect such abnormalities at an early stage to plan treatment and avoid future complications. Cone beam computed tomography images also play an important role.

Esthetic reconstruction of the anterior teeth area following a combined periodontic-orthodontic treatment in adult periodontal patients / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the role of the combined periodontic-orthodontic treatment in the esthetic reconstruc- tion of the anterior teeth area following periodontitis.</p><p><b>METHODS</b>Thirteen adult patients with anterior teeth displacements were treated. The probing pocket depth (PD; 102 teeth, 612 sites), bleeding on probing (102 teeth, 204 sites), papilla index (PI; 128 papillae), and papillary height (PH; 128 papillae) of each patient were assessed at baseline, 3 months after the initial therapy, and the end of the orthodontic treatment. Non-parametric and paired-sample t tests were carried out for the statistical analysis of the data.</p><p><b>RESULTS</b>Three months after initial therapy, the sites with PD ≤ 3 mm accounted for 79.58% (487/612) of the observed teeth, and 88.73% (181/204) of the buccal and lingual sites of the teeth showed negative bleeding on probing. These findings were better than those at baseline [26.31% (161/612) and 22.06% (45/204), respectively] (P < 0.05), but no sig- nificant difference was observed compared with pro-orthodontic treatment (P > 0.05). Prior to orthodontic treatment, the levels of the PI of 8 and 21 papillae were III and II, respectively, among the 128 observed papillae. After the orthodontic treatment, 51 papillae were at level III and 68 papillae were at level II. The PH of the 102 papillae was 2.84 mm ± 0.62 mm after ortho- dontic treatment. This result indicated significant difference compared with that of pre-orthodontic treatment (1.69 mm ± 0.57 mm) (P < 0.05).</p><p><b>CONCLUSION</b>After initial therapy, moderate orthodontic teeth movements may reconstruct the interproximal soft tissue, with esthetic improvement of the papillary level and resolution of the periodontal defects.</p>

Migración de caninos inferiores: reporte de un caso y reseña de la literatura / Transmigrant impacted mandibular canines: report of a case and review of the literature

Objetivo: el objetivo de este trabajo es presentar la exodoncia de un canino inferior izquierdo transpuesto y evaluar las alternativas terapéuticas frente a casos similares. Caso clínico: se desarrolla el caso de una mujer de 30 años de edad con migración del canino inferior izquierdo. Conclusión: se destaca la importancia de otener un diagnóstico clínico y radiográfico temprano para poder realizar tratamientos precoces, a fin de evitar la migración y sus posibles complicaciones. Se enfatiza también la necesidad del estudio anatomopatológico de los tejidos blandos obtenidos con la pieza quirúrgica.

Effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats

OBJECTIVE@#To investigate effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats.@*METHODS@#Eighty SD rats were randomly divided into 4 groups, blank control group (group A) with 5 rats, treatment normal group (group B) with 25 rats, inflammation control group (group (group C) with 25 rats, inflammation treatment group (group D) with 25 rats. Immunohistochemistry and histomorphometric analysis was performed to measure the expression of IL-6, IL-8 and the first molar to the recent movement in the distance.@*RESULTS@#The expression of IL-8 reached a maximum on day 5 and declined thereafter in group B; the expression of IL-6 reached a maximum on day 5 in group B. The expression of IL-6 and IL-8 was gradually weakened with time in group C. The expression of IL-6 and IL-8 were high, and reached a maximum on day 5 and declined thereafter in group D. AD of positive cells in group D were higher than group B at each time point (P<0.05). The time which 0.49 N orthodontic force was loaded was longer, orthodontic tooth movement distance was greater. Movement distance in group D were longer than group B (P<0.05).@*CONCLUSIONS@#Orthodontic force as well as inflammatory stimulus can evoke the expression of IL-6 and IL-8. Under the combined effects of inflammation and orthodontic force, the expression of IL-6, IL-8 will increase.

Transmigrated teeth / Transmigração dentária

Pre-eruptive migration of a tooth across the midline is called transmigration. This article reviews the literature on tooth transmigration. In the literature there is no consensus on the definition of true cases of transmigration and impacted teeth. Transmigration is a rare phenomenon that typically affects the mandibular canines. There is no known etiology for its occurrence, however, there are many and varied etiological factors involved in transmigrated teeth, such as ectopic growth of the tooth bud, retention or premature loss of a primary tooth, inadequate eruption space and excessive length of crown. Genetic factors, endocrine disorders and trauma have also been also proposed as etiological factors. In most clinical reports, transmigrated teeth were found in a horizontal position, below the apices of the erupted teeth and in the majority of cases, such a migrated tooth remains impacted; however, it may sometimes erupt later in its new position. When it is diagnosed in radiographic exams, careful evaluation is necessary in order to establish the most adequate treatment. Extraction of the transmigrated tooth appeared to be the only choice of treatment.

A migração pré-eruptiva de um dente através da linha média é chamada de transmigração. O objetivo deste artigo é apresentar uma revisão da literatura sobre a transmigração dentária. Na literatura não há consenso sobre a definição de casos de verdadeiros de transmigração e dentes impactados. Transmigração é um fenômeno raro, que normalmente afeta os caninos inferiores e a sua etiologia é desconhecida, porém vários fatores etiológicos podem estar envolvidos nos casos de transmigração, tais como o crescimento ectópico da raiz do dente, retenção ou perda prematura de um dente decíduo, espaço insuficiente erupção e comprimento excessivo da coroa. Fatores genéticos, doenças endócrinas e trauma também foram citados como possíveis fatores etiológicos. Nos relatos clínicos os dentes transmigrados foram encontrados em posição horizontal, abaixo os ápices dos dentes irrompidos e na maioria das vezes, um dente com transmigração permanece impactado; no entanto, posteriormente, pode irromper em sua nova posição. Quando diagnosticado, por exames radiográficos, é necessário um planejamento criterioso para o estabelecimento do tratamento mais adequado. A exodontia é o tratamento de escolha para os casos de transmigração dentária.

First case of bimaxillary transmigration of impactedcanines: report of a rare case and review of literature / Primeiro caso de transmigração bimaxilar de caninosimpactados: relato de um caso raro e revisão da literatura

Objective: To present a rare case of bimaxillary transmigration of impacted canines. Discussion: Preeruptivemigration of a tooth across the midline is termed transmigration. Transmigration typically affectsthe mandibular canines, but occurs rarely in maxillary canines as well. Transmigration of mandibular canineacross the midline is rare. An even less common finding is transmigration of maxillary canine acrossthe midline. The least common finding is bimaxillary occurrence of canines transmigration. Conclusion:Migration of both upper and lower canine teeth on the same side across the midline is called bimaxillarytransmigration, which is a very rare phenomenon of oral and maxillofacial complex, often undetected inroutine dental examination, neither clinical, nor periapical radiographic examination.

Objetivo: Apresentar um caso raro de transmigração bimaxilar de caninos impactados. Discussão: A migraçãopré-eruptiva de um dente através da linha média é denominado transmigração. A transmigraçãotipicamente afeta os caninos inferiores, mas pode ocorrer raramente em caninos superiores também. Transmigraçãode canino inferior através da linha média é rara, porém um achado ainda menos comum é a ocorrênciade transmigração bimaxilar de caninos. Conclusão: A migração de caninos superiores e inferiores nomesmo lado e cruzando a linha média é chamada de transmigração bimaxilar, um fenômeno raro de sistema bucal e maxilofacial, frequentemente diagnosticado em exame clínico odontológico de rotina ou exame radiográficoperiapical.

Unusual intraosseous transmigration of impacted tooth

Transmigration of an impacted tooth through the symphyseal suture is a rare and special developmental anomaly of unknown etiology that is unique to the mandibular canine. Maxillary canine transmigration is even rarer. Transmigrated canines are particularly significant due to the aesthetic and functional importance. A maxillary lateral incisor crossing the mid-palatal suture has never been reported in the literature. The aim of this report is to present the first case of simultaneous transmigration of a lateral incisor and canine in the maxilla. The paper also reports four unusual cases of unilateral canine transmigration in the maxilla and mandible and successful eruption of one of the transmigrated mandibular canines following orthodontic traction. Etiology of transmigration and its clinical considerations are also discussed.

Corrección de plano oclusal mediante implantes oseointegrados / Correcting the occlusal plane through osseointegrated implants

Se presenta en el siguiente artículo un caso donde la migración dentaria ha generado como resultado un plano oclusal descendido. Una vez que se ha decidido resolver el caso mediante terapia con implantes, se describen las maniobras que se habrán de realizarpreviamente en el tejido óseo de modo de acondicionarlo, teniendo en cuenta que de éstas dependerá el éxito del tratamiento. La ubicación tridimensional del implante utilizando el proyecto rehabilitador como base, será fundamental para restablecer lafuncionalidad y la estética, con un plano en correcta ubicación.

This paper shows a case in which tooth migration has resulted in a lowered occlusal plane. Upon deciding to solve the case using implant therapy, the techniques to be used for the preparation the bone tissue are described, taking into consideration that the success of the treatment will depend on said techniques. The three-dimensional location of the implant in the rehabilitated tissue, will be basic for the reestablishment of functionality and aesthetics, with a plane that is properly located.

Clinico-radiographic examination of odontogenic myxoma with displacement of unerupted upper third molar: review of the literature / Examen clínico-radiográfico de un mixoma odontogénico con desplazamiento de un tercer molar no erupcionado: revisión de la literatura

Odotogenic myxoma is a benign tumor which presents in 3 percent to 6 percent of all odontogenic tumors. According to the WHO classification, multiple radiolucent areas of varying size, separated by straight or curved bony septa with poorly defined borders are the radiologic characteristics of the condition. We report the case of maxillary odontogenic myxoma in a 21 year old man. The radiological feature of the current case was interesting, due to the size of the lesion and severe displacement of the upper third molar.

El mixoma odontogénico es un tumor benigno que se presenta en el 3 por ciento a 6 por ciento de todos los tumores odontogénicos. De acuerdo a la clasificación de la OMS, las características radiológicas de esta patología presentan múltiples áreas radiolúcidas de tamaño variable, separadas por tabiques óseos rectos o curvos, con márgenes mal definidos. Presentamos un caso de mixoma odontogénico maxilar en un hombre de 21 años. La característica radiológica es interesante, debido al tamaño de la lesión y al desplazamiento severo del tercer molar superior.

Three-dimensional finite element analysis of maxillary incisor retraction with step-shaped vertical closing loop / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the displacement and stress distribution of upper incisors in three-dimensional (3D) space controlled by step-shaped vertical closing loop.</p><p><b>METHODS</b>The maxillary teeth and alveolar bone of a volunteer with normal occlusion were scanned with 3D spiral CT. Modeling and calculation were only carried out on right upper central incisor, lateral incisor and their alveolar bone in order to simplify the procedures. A 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was developed using Ansys finite element package. Finally, a 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was established based on mirror symmetry principle. The displacement of maxillary incisors and stress distribution in periodontal tissues were analyzed.</p><p><b>RESULTS</b>When step-shaped vertical closing loop was simply drew back 1 mm, the maximum displacement of upper central incisor in labial and lingual direction were 5.29 × 10(-2) and 0.71 × 10(-2) mm; 10.47 × 10(-3) and 10.20 × 10(-3) mm in gingival and occlusal direction, 10.26 × 10(-3) and 1.63 × 10(-3) mm in medial and distal direction; the maximum displacement of upper lateral incisor in labial and lingual direction were 3.31 × 10(-2) and 0.41 × 10(-2) mm, 10.52 × 10(-3) and 5.10 × 10(-3) mm in gingival and occlusal direction, 6.29 × 10(-3) and 4.64 × 10(-3) mm in medial and distal direction, the displacement trend of them were moving lingually and gingivally similar to bodily movement. The stress peach of upper central incisor, periodontal ligament and alveolar bone were 31.35, 2.52 and 4.64 MPa, the stress peach of upper lateral incisor, periodontal ligament and alveolar bone were 19.59, 1.28 and 4.12 Mpa, the stress distribution of them were similar and the periodontal ligament buffered the stress imposed on the tooth.</p>

Orthodontic treatment for maxillary anterior pathologic tooth migration by periodontitis using clear aligner

PURPOSE: Pathologic tooth migration (PTM) is a tooth displacement which is derived from imbalance of tooth retention force and is dominantly found out in maxillary anterior area. PTM in maxillary anterior area was tried to corrected with periodontal treatment and a clear aligner in this study and the result was evaluated clinically and radiographically. METHODS: For the treatment of a patient with chronic periodontal disease accompanied by maxillary anterior pathologic tooth migration, clear aligner was applied to move teeth after a series of case-related periodontal therapy. Clinically, probing depth, gingival recession, clinical attachment level and mobility were measured pre- and post-treatment, and radiographic examination was performed as well. RESULTS: Clinically, we found the decrease of the probing depth, gingival recession, clinical attachment level and mobility. And we could also acknowledge the reduction of vertical and horizontal dimension on infrabony defect radiographically. However, it is still controversial if there was an actual bone filling. CONCLUSIONS: Clear aligner is an effective appliance to move teeth since it costs little in terms of expense and time. In addition, it wraps whole crowns, providing advantages to deal with crowding, spacing, and size of arch. In short, clear aligner could be a useful treatment option for PTM patient, since it provides decreased probing depth, gingival recession, clinical attachment level, mobility and esthetical restoration.