ABSTRACT
ABSTRACT It is undeniable that extra-alveolar mini-implants anchorage has revolutionized Orthodontics. Correspondingly, the proper understanding of mini-implants biomechanics allowed to broaden the range of dental movements as never seen before in clinical practice. However, in order to produce better treatments, especially regarding the effects in occlusal plane, it is important to be aware of the numerous possibilities of applying force systems based on skeletal anchorage. Thus, this paper aims to address, by means of clinical cases, the application of biomechanics concepts that are extremely relevant to the proper employment of extra-alveolar mini-implants.
RESUMO É inegável que a ancoragem com mini-implantes extra-alveolares revolucionou a nossa especialidade. No mesmo sentido, o correto entendimento da biomecânica com mini-implantes permitiu ampliar a gama de movimentos dentários como nunca visto na prática clínica. Deve-se, porém, atentar às diversas possibilidades dos sistemas de aplicação das forças decorrentes do uso da ancoragem esquelética, com vistas a produzir tratamentos cada vez mais eficientes, principalmente em relação aos efeitos no plano oclusal. Assim, o presente artigo versa, por meio de casos clínicos, sobre a aplicação de conceitos da biomecânica que são extremamente relevantes para o correto emprego dos mini-implantes extra-alveolares.
Subject(s)
Orthodontics , Dental Implants , Orthodontic Anchorage ProceduresABSTRACT
OBJECTIVE: The purpose of this study was to analyze stress distributions in the roots, periodontal ligaments (PDLs), and bones around cylindrical and tapered miniscrews inserted at different angles using a finite element analysis. METHODS: We created a three-dimensional (3D) maxilla model of a dentition with extracted first premolars and used 2 types of miniscrews (tapered and cylindrical) with 1.45-mm diameters and 8-mm lengths. The miniscrews were inserted at 30°, 60°, and 90° angles with respect to the bone surface. A simulated horizontal orthodontic force of 2 N was applied to the miniscrew heads. Then, the stress distributions, magnitudes during miniscrew placement, and force applications were analyzed with a 3D finite element analysis. RESULTS: Stresses were primarily absorbed by cortical bone. Moreover, very little stress was transmitted to the roots, PDLs, and cancellous bone. During cylindrical miniscrew insertion, the maximum von Mises stress increased as insertion angle decreased. Tapered miniscrews exhibited greater maximum von Mises stress than cylindrical miniscrews. During force application, maximum von Mises stresses increased in both groups as insertion angles decreased. CONCLUSIONS: For both cylindrical and tapered miniscrew designs, placement as perpendicular to the bone surface as possible is recommended to reduce stress in the surrounding bone.
Subject(s)
Bicuspid , Dentition , Finite Element Analysis , Head , Maxilla , Periodontal LigamentABSTRACT
O número de tratamentos ortodônticos em pacientes adultos, que frequentemente apresentam problemas periodontais, ausências dentárias e próteses, aumentou muito nos últimos tempos. Com este novo panorama, novas estratégias devem ser utilizadas para atender às necessidades específicas destes tipos de pacientes, como estética, forças suaves, menor tempo de tratamento e menor dependência da colaboração. O uso de ancoragem esquelética associada aos aparelhos autoligados reduz o número de extrações de pré-molares, emprega uma mecânica simples e eficiente, minimiza os efeitos colaterais indesejados, diminui a necessidade de colaboração do paciente e torna os tratamentos mais previsíveis. Este artigo ilustra a correção de uma má oclusão de Classe II de Angle, de natureza dentoalveolar, cujo caso também apresentava mordida cruzada e problemas periodontais. Foram utilizados miniparafusos ortodônticos para efetuar a distalização do arco superior e corrigir a Classe II, associados ao sistema de aparelhos autoligados com fios termoativados. Esta associação trouxe benefícios na correção ortodôntica da paciente com problemas periodontais, pois houve ganho de inserção clínica por meio da formação de epitélio juncional longo, especialmente na região anterossuperior, após movimentação ortodôntica leve, realizada com o sistema de aparelhos autoligados. Tal associação reduziu a intensidade das forças aplicadas, evitou o uso de elásticos de Classe II e diminui a quantidade de consultas sem prejudicar a eficiência da correção.
The number of orthodontic treatment for adult patient has increased considerably. These patients frequently present periodontal conditions, absent teeth and prosthesis. In this scenario, new strategies must be used to meet specific needs of these patients such as: gentle force, aesthetics and briefer treatments requiring lower compliance. Skeletal anchorage associated with sel-ligating appliances reduces the number of pre-molars extraction. It uses simple and efficient mechanics, minimizes undesirable side-effects and reduces the need of compliance of patients, resulting on a more predictable treatment. The present article illustrates the correction of Angle Class II malocclusion of dentoalveolar nature, associated to crossbite and periodontal conditions. Orthodontic mini-screws were used to perform distalization of the maxillary arch for the correction of Class II, combined with self-ligating appliance with heat-activated wire. This association brought benefits to the corrective orthodontic treatment of a patient with periodontal conditions since there was a gain on clinical attachment due to the formation of long junctional epithelium, especially on the anterosuperior region after light orthodontic movement performed with self-ligating appliance. The association also reduced the forces applied; avoid the use of Class II elastics and reduced the number of appointments without compromising the efficiency of the correction.
Subject(s)
Humans , Female , Middle Aged , Malocclusion, Angle Class II , Orthodontic Appliances , PeriodonticsABSTRACT
OBJECTIVE: The purpose of this experimental study was to evaluate the effect of immediate orthodontic loading on the stability at the bone-implant interface of titanium miniscrews in a rabbit model. METHODS: Forty titanium miniscrews (1.6 mm diameter, 8 mm length) were inserted in the tibiae of 10 rabbits. Twenty test group miniscrews were subjected to continuous orthodontic forces of 200 g immediately after implantation for a period of 6 weeks. The remaining 20 control group miniscrews were left unloaded for the same follow-up interval. Removal torque values were recorded using a digital torque gauge. An independent t-test was performed. RESULTS: All the miniscrews were stable, and exhibited no mobility or displacement throughout the experimental period. Histologically, miniscrews were well-integrated into bone. No statistically significant differences in removal torque data were found between the loaded test and the unloaded control groups. CONCLUSIONS: These findings suggest that titanium miniscrews can be used as anchoring units for orthodontic tooth movement immediately after insertion.