Regular papers Biomechanical study of changes in buccal bone structure induced by expansion screw

Abstract

Orthodontics searches for reaching occlusal equilibrium and the functionality of the stomatognathic system: bones, teeth, periodontal ligament, tongue, temporomandibular joints (TMJ) and other oral biological structures, that can happen during the growth of a person. When this equilibrium is not reached, morphological changes, known as malocclusions, occur. Malocclusion problems resulting from the maxilla’s narrowing are commonly found in the population. They lead to dysfunctions in the jaw joint and alterations in chewing, speech and breathing. Patients should be treated precociously so that the results allow for proper aesthetic improvements. Steady dental position and a remodeled bone contour are desired through a functional occlusal gear for attaining normality. These bone growth disturbances cause an unfavorable esthetic effect that impacts in the self-esteem of the patients. Malocclusion patients, mainly children and teenagers, as well as young adults, need orthodontic and orthopedic treatment to open the maxillary suture and bone remodeling of the palatal contour and a better architecture of the dental arches. The orthodontist should know the level of applied forces in the oral correction devices and the clinical follow up of the treatment. The treatment involves reactions of organic structures, starting with inflammatory process, prevention pain and irreversible injuries to live tissues as well as uncontrolled bone resorption and lost of tooth elements (Proffit, 1995; Burst & MacNamara, 1995). The connection between physical phenomena and organic reactions, in addition to knowledge of the material properties, is essential to get the expected results from the treatment. One of the techniques for correction of this pathology requires the installation of a mobile device in the mouth that allows bone remodeling, with a bone resorption area and deposition of neoformed bone tissue. It is necessary to use a methodology that correlates the imposed displacement with the bone structure deformation, cortical as well as trabecular, and the impact absorption by the mucosa, quantifying the level of forces and stresses reached. The purpose is to arrive at a less traumatic application of forces, attenuating painful symptoms such as chronic headaches, partial necrosis of the bone and even the loss of dental elements. The mechanisms of the dental movement phases and bone remodeling should preserve the biological and functional integrity of the stomatognathic system, not only the dental elements but also the occlusal gear, the periodont and the temporomandibular joint, as well the aesthetic and individual characteristics of the patients (Sandy et al., 1993). Expansion screw is the main orthopedic accessory used to allow bone remodeling in the dental arch with objective to correct deviations in the shape and boundary of the buccal bone and to reach an adequate dental occlusion (Haas, 1965; Silva Filho, 2007).