ABSTRACT
@#In many cases, tooth movement over a considerable distance is needed to meet the major goal of orthodontic treatment, which has always been to correct malocclusion and improve the facial profile in patients with skeletal malocclusion. However, tooth movement over a considerable distance also carries risks of dehiscence, fenestration, root exposure, and so forth. The reason lies in neglecting many limits for tooth movement, especially anatomical characteristics. This review focuses on structural limits for orthodontic molar movement, such as the alveolar cortex, the maxillary sinus floor, and the mandibular canal. In addition, we set the strategy in clinical orthodontics. For the alveolar cortex and the mandibular canal, orthodontists are recommended to move the root away from the cortical bone initially and formulate personalized molar movement plans according to clinical examination and cone-beam computed tomography (CBCT) and other imaging examinations. First, the molar root was controlled by torque away from the bone plate, and then, the molar movement amount and direction were controlled according to the personalized movement path. In regard to the maxillary sinus floor, light and continuous forces and scientific biomechanics are suitable for bodily tooth movement. In summary, better therapeutic efficacy and long-term stabilization could be achieved by circumventing the limits and risks caused by anatomical limitations and characteristics.
ABSTRACT
@#The normal torque angle of the maxillary anterior teeth is an important factor in the aesthetics and function of the anterior teeth, and torque control of the front teeth is an extremely important aspect of the correction process. At present, the normal torque angle of the front teeth is among the phase Ⅲ clinical test items recognized by the American orthodontic professional committee; consequently, good control of front teeth torque is of great significance to the aesthetics of the upper anterior teeth. In this paper, the influence of a lip appliance on the bad torque of upper anterior teeth and the associated methods of control are reviewed in detail. The advantages and disadvantages of various control methods for the anterior teeth and the significance of correct anterior teeth torque angle are summarized. The existing research results indicate that the torsion of a straight arch wire applied directly to individual teeth is too great, making it difficult to enter the groove. Although the bending of the arch wire overcomes these shortcomings, the procedure is cumbersome; it stimulates the soft tissue of the vestibular groove and increases the patient’s discomfort. The bending mechanism of the rocking chair is more complicated; it is greatly affected by the friction between the arch wire and the bracket and is not conducive to closing the tooth extraction gap using the sliding method. The portal auxiliary arch and the single bending torque are suitable for correcting the torque angle of a single tooth. Auxiliary arch torque can be used to correct the upright upper anterior teeth during the process of closing the extraction space and after adduction; therefore, this procedure is worth popularizing. However, the accuracy of orthodontic control of anterior teeth torque requires further study.
ABSTRACT
El presente artículo muestra el diseño de un dispositivo háptico concebido para aplicaciones biomédicas, específicamente para medicina quirúrgica en la que el operador, a través del sentido del tacto, sienta y manipule objetos simulados en un ambiente tridimensional y tele-operado. La interfaz háptica que se presenta corresponde a un robot tipo serie, con una arquitectura de cuatro grados de libertad que le permite al usuario posicionar y orientar el efector final en el entorno de trabajo. Para el estudio de los movimientos del robot se parte del modelado geométrico y dinámico del mismo, hasta la implementación de un controlador por par calculado. Finalmente, se realiza la simulación de la interfaz háptica en un ambiente virtual.
This paper presents the design of haptic device that is conceived for biomedical applications. Specifically, the device can be used for surgery training allowing the user to feel and handle simulated objects a tridimensional and tele-operated environment. The haptic interface is a serial robot with four degrees of freedom that allows to set the orientation and position of the end-effector into the work environment. Kinematic and dynamic models are used to study the robot movements and to build a calculated torque controller. Finally, a simulation of the haptic interface is done in a virtual environment.