Segmented mechanics for traction of impacted maxillary canine: case report with a 3-year follow-up

Abstract

Young patients are increasingly concerned with smile aesthetics, resulting in the early visit to the dental office. It is of great importance that professionals such as orthodontists, pediatric dentists, and general practitioners are aware of the potential changes in positioning and development that may compromise aesthetics, considering they may prevent future complex orthodontic treatments. This case report describes the treatment of a patient aged 9 years and 4 months, who complained at assessment about the size and position of maxillary incisors. Clinically, the patient presented atresic maxilla and eruption of teeth 12 and 22. The poor positioning of tooth 22 alerted for the potential retention of tooth 23. A two-phase treatment was proposed, including an intercepting phase and a corrective phase. In the intercepting phase, rapid maxillary expansion (RME) was performed, which increased the room for eruption of tooth 23 and prevented the collapse of tooth 22. After the activation period, the Haas expander was locked and removed six months later. Twenty-five months after the removal, the second phase started with fixed corrective orthodontics and traction of tooth 23, for which the enamel was drilled and traction was performed using the segmented technique with a 0.019" x 0.025" Titanium Molybdenum Alloy (TMA) cantilever and anchorage in passive transpalatal arch (PTA). The use of this technique minimizes the side effects on the teeth adjacent to tooth 23 and enamel drilling prevents potential losses of the traction device by detachment. After 4 months of segmented mechanics, the devices were removed and the PTA was maintained. Twenty-six months later, the patient was 14 years and 4 months old, presenting direct subdivision Class III molar relationship, upper and lower crowding, and unsatisfactory relationship between bone bases due to the excessive mandibular growth. A new RME was performed, and after 3 months a Capelozza Pattern III fixed appliance was installed in the lower arch. Additionally, an upper fixed appliance was installed after the RME retention period. One year and 4 months later, the appliances were removed and a maxillary Hawley plate was installed with a 0.6-mm fixed mandibular intercanine arch. The follow-up lasted 3 years and 4 months and the results were maintained, preserving the occlusal and facial characteristics.

Effects of stress relaxation in beta-titanium cantilevers used in orthodontic mechanics

“…Immediately after the cantilevers were preactivated (baseline), they were tested using a tabletop universal testing machine (Series 4400 System, Instron, Norwood, MA), equipped with a load cell of 10 3 cN (load accuracy of 0.5%), at the testing speed of 5.0 mm per minute. Bluehill 2 Universal static testing software was used to set variables of the test and export data.…”

“…Anchored at only one end, a cantilever is a beam with which the orthodontist can easily and accurately predict tooth movement. [1][2][3] By producing effects on the tooth in all three planes, controlling and individualizing the forces applied, cantilevers can be applied to provide intrusion or extrusion of one or several teeth simultaneously. They can also perform tractions, uprightings, retractions, and early corrections of the deep curve of Spee.…”

“…They can also perform tractions, uprightings, retractions, and early corrections of the deep curve of Spee. [1][2][3][4][5][6] Because of their formability and springback characteristics, titanium-molybdenum alloys, also called β-titanium, are often used for the manufacturing of cantilevers. [1][2][3][4][5][7][8][9][10] This alloy in straight-wire applications can be deflected 105 percent more than stainless steel without permanent deformation, and its stiffness makes it ideal in applications where less force is required but a lower modulus of elasticity would be inadequate to develop the required force magnitudes.…”

“…[1][2][3][4][5][6] Because of their formability and springback characteristics, titanium-molybdenum alloys, also called β-titanium, are often used for the manufacturing of cantilevers. [1][2][3][4][5][7][8][9][10] This alloy in straight-wire applications can be deflected 105 percent more than stainless steel without permanent deformation, and its stiffness makes it ideal in applications where less force is required but a lower modulus of elasticity would be inadequate to develop the required force magnitudes. 11 Therefore, the use of β-titanium alloys enables the construction of cantilevers with simpler designs, saving time during the clinical procedures.…”

Dentes supranumerários impactados em região de nervo mentoniano: relato de caso

“…A etiologia das impactações ainda é um ponto bastante divergente entre as pesquisas já realizadas, inúmeros autores descrevem distintas condições relevantes que levam um dente a impactar, sendo eles: origem genética, obstrução dos incisivos laterais, deficiência maxilar e distúrbios relacionados ao folículo dentário (Mohammed et al, 2020;Lima et al, 2019;Ngan et al, 2005;Franco et al, 2005).…”