Concentración de la enzima AST (aspartato aminotransferasa) en dientes sometidos a fuerzas ortodónticas intrusivas / Enzyme concentration AST (aspartate transaminase) teeth in orthodontic forces under intrusive

Introducción: Reportes en la literatura describen, como las fuerzas ortodónticas aplicadas durante los movimientos dentales conllevan a reacciones pulpares, alteraciones y molestias en un tratamiento de ortodoncia. La aspartato aminotransferasa (AST) es una enzima catalogada como un indicador de necrosis celular; sin embargo, es necesario evaluar su actividad en dientes sometidos a las diferentes fuerzas que se aplican durante un tratamiento ortodóntico. Objetivo: Comparar las concentraciones de aspartato aminotransferasa en tejido pulpar de dientes sometidos a fuerzas ortodónticas intrusivas y dientes libre de fuerzas. Método: Se realizó un estudio cuasi-experimental de boca dividida en 34 premolares superiores procedentes de 20 sujetos que requerían extracción de los mismos para fines ortodónticos. 20 premolares fueron expuestos por 48 horas a fuerzas intrusivas (75 g/fuerza). Los dientes contralaterales fueron usados como grupo control. Se extrajo el tejido pulpar y se midió la concentración de AST. Se tuvo en cuenta una significancia estadística de p<0,05. Resultados: Al realizar las comparaciones de las concentraciones de la enzima en ambos grupos no se encontró una diferencia estadísticamente significativa (p= 0,436). El grupo control mostró una concentración promedio de 1,78±1,13 U/mg mientras que los premolares expuestos a fuerzas intrusivas reportaron una media de 1,94±1,2 U/mg. Conclusión: La actividad de la AST a nivel del tejido pulpar no tiene variación significativa al inducir movimientos intrusivos con fuerzas aproximadas de 75 g/fuerza en la muestra estudiada

Background: Reports in the literature describe as orthodontic forces applied during dental movements lead to pulp reactions, alterations and discomfort in orthodontic treatment. Aspartate aminotransferase (AST) is an enzyme classified as an indicator of cell necrosis; However, it is necessary to evaluate their activity in teeth subjected to various forces applied during orthodontic treatment. Objective: To compare aspartate aminotransferase concentrations in teeth pulp tissue subjected to intrusive orthodontic forces and forces free teeth. Method: A quasi-experimental study of mouth divided into 34 premolars from 20 subjects requiring removal thereof for orthodontic purposes was performed. 20 premolars were exposed for 48 hours to intrusive forces (75 g/force). Contralateral teeth were used as control group. the pulp tissue was removed and the concentration of AST was measured. statistical significance of p <0.05 was taken into account. Results: When making comparisons of enzyme concentrations in both groups not a statistically significant difference (p= 0.436) was found. The control group showed an average concentration of 1.78±1.13 U/mg while the premolars exposed to intrusive forces reported an average of 1.94±1.2 U/mg. Conclusion: AST activity level does not vary pulp tissue by inducing movements intrusive forces approximate 75 g/force

Effects of different types of tooth movement and force magnitudes on the amount of tooth movement and root resorption in rats.

OBJECTIVE: To investigate differences in the amount of tooth movement and root resorption that occurred after tipping and bodily movement of the maxillary first molar in rats. MATERIALS AND METHODS: Ten-week-old female Wistar rats were divided into two groups according to type of tooth movement and subdivided into four subgroups according to the magnitude of applied force. Nickel-titanium closed-coil springs exerting forces of 10, 25, 50, or 100 g were applied to the maxillary left first molars to induce mesial tooth movement. We designed a novel orthodontic appliance for bodily tooth movement. Tooth movement distance and root resorption were measured using microcomputed tomography and scanning electron and scanning laser microscopy. RESULTS: The amount of tooth movement in the bodily tooth movement group was less than half that in the tipping tooth movement group. The greatest amount of tooth movement occurred in the 10-g tipping and 50-g bodily tooth movement subgroups, and the amount of tooth movement decreased with the application of an excessive magnitude of force. Conversely, root resorption increased when the heavier orthodontic force was applied in both groups. Root resorption in the tipping tooth movement group was approximately twice that in the bodily tooth movement group. CONCLUSIONS: Root resorption in the tipping tooth movement group was more pronounced than that in the bodily tooth movement group. Although the amount of tooth movement decreased when extremely heavy forces were applied, root resorption increased in both the tipping and bodily tooth movement groups in rats.

Osteocalcin and N-telopeptides of type I collagen marker levels in gingival crevicular fluid during different stages of orthodontic tooth movement.

INTRODUCTION: The aim of the study was to quantitatively and qualitatively analyze changes in the gingival crevicular fluid (GCF) during orthodontic movement by assessing the levels of cross-linked N-telopeptides of type I collagen marker (NTx) and osteocalcin (OC) activity. METHODS: Twenty patients requiring all first premolars to be extracted were selected and treated with conventional straight-wire mechanotherapy. The canines were retracted with closed-coil springs. The maxillary canine on one side acted as the experimental site, and the contralateral canine was the control. GCF was collected from around the canines before retraction, and 1 hour, 1 day, 7 days, 14 days, and 21 days after retraction. GCF NTx and OC levels were estimated and compared with the control side. RESULTS: The results showed statistically significant changes in NTx and OC levels on days 7, 14, and 21 when we compared the experimental and control sides. The peak in all activity of the variables occurred on day 14 after retraction. CONCLUSIONS: The study showed that NTx and OC levels can be successfully estimated in the GCF, and its increased levels might indicate the active tooth movement phase in orthodontic therapy.

Simulação 3D de movimento ortodôntico / 3D simulation of orthodontic tooth movement

OBJETIVO: desenvolver e validar, através do Método dos Elementos Finitos (MEF), um modelo numérico tridimensional (3D) de um incisivo central superior para simular o movimento dentário. MÉTODOS: esse modelo contempla a unidade dentária, o osso alveolar e o ligamento periodontal. Permite a simulação dos diferentes movimentos dentários e a determinação dos centros de rotação e de resistência. Limita o movimento ao espaço periodontal, registrando a direção, quantificando o deslocamento dentário e as tensões iniciais no ligamento periodontal. RESULTADOS: a análise dos deslocamentos dentários e das áreas que recebem tensões iniciais possibilita determinar os tipos de movimentos dentários. Com base nas forças ortodônticas, é possível quantificar a intensidade das tensões em cada região do dente, do ligamento periodontal ou do osso alveolar. Com base nas tensões axiais ao longo do ligamento periodontal e da tensão capilar, é possível predizer, teoricamente, as regiões em que deve ocorrer a remodelação óssea. CONCLUSÃO: o modelo foi validado pela determinação do módulo de elasticidade do ligamento periodontal de forma compatível com dados experimentais existentes na literatura. Os métodos utilizados na construção do modelo permitiram a criação de um modelo completo para uma arcada dentária, o qual possibilita realizar variadas simulações que envolvem a mecânica ortodôntica.

OBJECTIVE: To develop and validate a three-dimensional (3D) numerical model of a maxillary central incisor to simulate tooth movement using the Finite Element Method (FEM). METHODS: This model encompasses the tooth, alveolar bone and periodontal ligament. It allows the simulation of different tooth movements and the establishment of centers of rotation and resistance. It limits the movement into the periodontal space, recording the direction, quantifying tooth displacement and initial stress in the periodontal ligament. RESULTS: By assessing tooth displacements and the areas that receive initial stress it is possible to determine the different types of tooth movement. Orthodontic forces make it possible to quantify stress magnitude in each tooth area, in the periodontal ligament and in the alveolar bone. Based on the axial stress along the periodontal ligament and the stress in the capillary blood vessel (capillary blood stress) it is theoretically possible to predict the areas where bone remodeling is likely to occur. CONCLUSIONS: The model was validated by determining the modulus of elasticity of the periodontal ligament in a manner consistent with experimental data in the literature. The methods used in building the model enabled the creation of a complete model for a dental arch, which allows a number of simulations involving orthodontic mechanics.

How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign.

INTRODUCTION: The purpose of this prospective clinical study was to evaluate the efficacy of tooth movement with removable polyurethane aligners (Invisalign, Align Technology, Santa Clara, Calif). METHODS: The study sample included 37 patients treated with Anterior Invisalign. Four hundred one anterior teeth (198 maxillary and 203 mandibular) were measured on the virtual Treat models. The virtual model of the predicted tooth position was superimposed over the virtual model of the achieved tooth position, created from the posttreatment impression, and the 2 models were superimposed over their stationary posterior teeth by using ToothMeasure, Invisalign's proprietary superimposition software. The amount of tooth movement predicted was compared with the amount achieved after treatment. The types of movements studied were expansion, constriction, intrusion, extrusion, mesiodistal tip, labiolingual tip, and rotation. RESULTS: The mean accuracy of tooth movement with Invisalign was 41%. The most accurate movement was lingual constriction (47.1%), and the least accurate movement was extrusion (29.6%)- specifically, extrusion of the maxillary (18.3%) and mandibular (24.5%) central incisors, followed by mesiodistal tipping of the mandibular canines (26.9%). The accuracy of canine rotation was significantly lower than that of all other teeth, with the exception of the maxillary lateral incisors. At rotational movements greater than 15 degrees, the accuracy of rotation for the maxillary canines fell significantly. Lingual crown tip was significantly more accurate than labial crown tip, particularly for the maxillary incisors. There was no statistical difference in accuracy between maxillary and mandibular teeth of the same tooth type for any movements studied. CONCLUSIONS: We still have much to learn regarding the biomechanics and efficacy of the Invisalign system. A better understanding of Invisalign's ability to move teeth might help the clinician select suitable patients for treatment, guide the proper sequencing of movement, and reduce the need for case refinement.

Biomecánica, aplicaciones clínicas (parte I) / Biomechanics, clinical applications (part I)

Este trabajo valoriza el diagnóstico frente a la tendencia simplista de utilizar recetas. Se requiere la dsecripción de la anomalía, determinar su naturaleza y su causa para luego establecer las metas del tratamiento y el plan de medidas para lograrlas. Los sistemas de fuerzas a aplicar pueden conocerse. Las respuestas biológicas están condicionadas por las características propias de cada individuo. Se definen los conceptos de fuerzas, momentos, cuerpos rígidos, transmisibilidad, centros de resistencia y rotación. Se ilustra con ejemplos de sistemas aplicados a los dientes, describiéndose los diferentes tipos de movimientos dentarios a obtenerse (AU)

In vivo determination of the centres of resistance of maxillary anterior teeth subjected to retraction forces.

This study was designed to locate the centres of resistance of consolidated units of two, four, and six anterior teeth during retraction in two human subjects. Initial displacements of these units were separately measured when retraction forces were applied at different levels by means of a device for displacement measurement using magnetic sensors and magnets. By calculating the angle of rotation from the displacements measured, the location of the centre of resistance was determined for each unit. The results showed that the centres of resistance of the two- and four-incisor units were approximately at the same position, whilst that of the six-tooth unit was observed to be more incisal. Clinically, this finding indicates that translation can be achieved with a smaller amount of moment-to-force ratio in en masse retraction than in two- or four-incisor retraction. The results also indicate that the location of the centre of resistance of the anterior segment during retraction may depend on the palatal alveolar bone height, rather than on the labial alveolar bone height.

Avaliaçäo da recidiva da sobremordida profunda: estudo longitudinal cefalométrico e de modelos / Evaluation of the relapse of the deep overbite: cephalometric longitudinal study and of models

A recidiva da sobremordida profunda apresenta-se, ainda, como uma incógnita. As divergências de opiniöes suscitadas pela literatura decorrem das diferentes metodologias, incluindo os materiais e os métodos, como também, dos diversos componentes envolvidos em sua etiologia. Revisando a literatura pertinente, os fatores que provavelmente encontram-se envolvidos com esta recidiva säo: o padräo de crescimento facial, as alturas faciais anteriores e posteriores, a altura do ramo ascendente e o comprimento do corpo da mandíbula, o ângulo goníaco, o ângulo interincisivos, a recidiva do apinhamento ântero-inferior e da sobressaliência, além da movimentaçäo dos incisivos e dos molares. Dentro deste contexto, propôs-se avaliar a recidiva desta má oclusäo observando-se os fatores relatados acima. Para a composiçäo da amostra, selecionaram-se 48 jovens, leucodermas, de ambos os sexos, que apresentavam, inicialmente, Classe I e Classe II, 1ª divisäo, com sobremordida de no mínimo 3,5mm, tratados com extraçöes dos quatro primeiros pré-molares. As tomadas radiográficas e os modelos de estudo foram obtidos em 3 fases: ao início, ao final e 5 anos após o tratamento ortodôntico. Os resultados permitiram concluir que os fatores dentários correlacionados com a recidiva da sobremordida profunda foram a sobressaliência, a movimentaçäo dos incisivos e dos molares e o ângulo interincisivos. Para os fatores esqueléticos, somente apresentou correlaçäo estatisticamente significante a variável N-Me (altura facial anterior total). Verificou-se, também, uma forte correlaçäo da quantidade de correçäo com a quantidade de recidiva