Extruded upper first molar intrusion: Comparison between unilateral and bilateral miniscrew anchorage

Abstract

Objective: The aim of his study was to evaluate the stress on tooth and alveolar bone caused by orthodontic intrusion forces in a supraerupted upper molar, by using a three-dimensional Finite Element Method (FEM). Methods: A superior maxillary segment was modeled in the software SolidWorks 2010 (SolidWorks Corporation, Waltham, MA, USA) containing: cortical and cancellous bone, supraerupted first molar, periodontal tissue and orthodontic components. A finite element model has simulated intrusion forces of 4N onto a tooth, directed to different mini-screw locations. Three different intrusion mechanics vectors were simulated: anchoring on a buccal mini-implant; anchoring on a palatal mini-implant and the association of both anchorage systems. All analyses were performed considering the minimum principal stress and total deformation. Qualitative analyses exhibited stress distribution by color maps. Quantitative analysis was performed with a specific software for reading and solving numerical equations (ANSYS Workbench 14, Ansys, Canonsburg, Pennsylvania, USA). Results: Intrusion forces applied from both sides (buccal and palatal) resulted in a more homogeneous stress distribution; no high peak of stress was detected and it has allowed a vertical resultant movement. Buccal or palatal single-sided forces resulted in concentrated stress zones with higher values and tooth tipping to respective force side. Conclusion: Unilateral forces promoted higher stress in root apex and higher dental tipping. The bilateral forces promoted better distribution without evidence of dental tipping. Bilateral intrusion technique suggested lower probability of root apex resorption.

Biomechanics for Orthodontic Intrusion of Severely Extruded Maxillary Molars for Functional Prosthetic Rehabilitation

“…In a finite element study, a unilateral force promoted higher stress in the root apex and higher dental tipping, and the bilateral forces promoted better distribution without evidence of dental tipping. However, the bilateral intrusion technique suggested a lower probability of root apex resorption [19], as applied in the present case.…”

Mini-implantes associados à ancoragem ortodôntica para intrusão de molares: Uma revisão de literatura

“…Considerando os limites da mucosa queratinizada, o mini-implante deve ser instalado o mais apical possível, atentando-se para que na maxila ele seja rosqueado mais perpendicularmente ao eixo do dente ou em um ângulo de até 30 a 45 graus para evitar tocar estruturas nobres como o seio maxilar (Poggio, 2006;Carano et al, 2005;Fonseca, 2019). Sugii et al (2018) realizaram uma pesquisa em um segmento de maxila modelado no software SolidWorks 2010 (SolidWorks Corporation, Waltham, MA, EUA), O modelo simula osso cortical e medular, primeiro molar extruído, tecido periodontal e acessórios ortodônticos. O modelo recebeu forças intrusivas aplicadas a partir de mini-implantes em três diferentes vetores, mecânica simulada a partir de ancoragem em mini-implante vestibular, localizado entre o primeiro e o segundo molar ligado por acessórios a um tubo duplo do mesmo lado, ancoragem em mini-implante palatino, localizado entre o primeiro e o segundo pré-molar, associado à um botão, e força bilateral, a associação de ambas.…”

“…Araújo et al (2008) sugeriu o uso de mini-implantes entre as raízes mesial e distal do molar a ser intruído, sendo um por vestibular e o outro por palatino, um deslocado para mesial e outro para distal. Segundo a pesquisa feita por Sugii et al (2018), os miniimplantes assim instalados, proporcionam um movimento dentário vertical controlado, evitando forças obliquas que promovam inclinações dentárias indesejadas. E em termos de efetividade de ancoragem, para Paccini et al (2016) o uso de dois miniimplantes é suficiente, pois se associado a um terceiro dispositivo não demonstrará ganhos significativos na ancoragem.…”

Immediate orthodontic load on dental implants: an option for adult treatment

“…It should be emphasized that it is important to use a bilateral force system, with insertion of miniscrews on the buccal and palatal sides, to minimize the tooth inclination and the possibility of root apex resorption. 24 For insertion of the endosseous implant in the edentulous space to serve as anchorage unit, a multidisciplinary orthodontic, prosthetic and esthetic planning was designed, considering the prosthetic space, need for tooth movement, position and size of future prosthetic crown. 14,25 In general, the literature indicates that immediate load can be applied to implants with primary stability whose torque during surgery reached between 35 and 60 N/cm.…”