Ione Helena Vieira Portella Brunharo

Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27ºC and 35ºC, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27ºC and 35ºC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27ºC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35ºC wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35ºC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region.

Surgical treatment of dental and skeletal Class III malocclusion

Orthodontic preparation for surgical treatment of skeletal Class III malocclusion involves joint planning with an oral and maxillofacial surgeon to address the functional and esthetic needs of the patient. In order to allow surgical manipulation of the jaws in the preoperative phase, the need to achieve a negative overjet through incisor decompensation often leads the orthodontist to extract the upper first premolars. This report illustrates an orthodontic preparation case where due to specific factors inherent in the patients psychological makeup retroclination of the upper incisors and proclination of the mandibular incisors was achieved without removing any teeth. This case was presented to the Brazilian Board of Orthodontics and Facial Orthopedics (BBO) in partial fulfillment of the requirements for obtaining the BBO Diploma.

Mechanical properties of NiTi and CuNiTi shape-memory wires used in orthodontic treatment. Part 1: stress-strain tests

OBJECTIVE This research aimed to compare, through traction tests, eight types of superelastic and heat-activated NiTi archwires, by six trade companies (GAC, TP, Ormco, Masel, Morelli and Unitek) to those with addition of copper (CuNiTi 27°C and 35°C, Ormco). METHODS The tests were performed in an EMIC mechanical testing machine, model DL10000, capacity of 10 tons, at the Military Institute of Engineering (IME). RESULTS The results showed that, generally, heat-activated NiTi archwires presented slighter deactivation loadings in relation to the superelastic ones. Among the archwires that presented deactivation loadings biologically more adequate are the heat-activated by GAC and by Unitek. Among the superelastic NiTi, the CuNiTi 27°C by Ormco were the ones that presented slighter deactivation loadings, being statistically (ANOVA) similar to the ones presented by the heat-activated NiTi archwires from Unitek. When compared the CuNiTi 27°C and 35°C archwires, it was observed that the 27°C presented deactivation forces of, nearly, ⅓ of the presented by the 35°C. CONCLUSIONS It was concluded that the CuNiTi 35°C archwires presented deactivation loadings biologically less favorable in relation to the other heat-activated NiTi archwires, associated to lower percentage of deformation, on the constant baselines of deactivation, showing less adequate mechanical behavior under traction, in relation to the other archwires.

Fios ortodônticos: conhecer para otimizar a aplicação clínica

The huge variety of orthodontic wires brands available in market might generate confusion as regard to the best choice for clinical application. Therefore mechanical properties knowledge about wires would help the professional to apply the best orthodontic technique depending on the treatment phase. The wires manufacturing evolution and the new orthodontic techniques proposed guided the market into the search for better quality alloys, in order to make them biologically more effective to teeth and support tissues. This paper aims to summarize some main characteristics of orthodontic wires related to their history, mechanical properties and clinical application as regard to individual phase of treatment.

Influence of surface treatment on shear bond strength of orthodontic brackets

INTRODUCTION The shear bond strength of orthodontic brackets bonded to micro-hybrid and micro-particulate resins under different surface treatment methods was assessed. METHODS Two hundred and eighty test samples were divided into 28 groups (n = 10), where 140 specimens were filled with Durafill micro-particulate resin and 140 with Charisma composite. In 140 samples, a coupling agent (silane) was applied. The surface treatment methods were: Phosphoric and hydrofluoric acid etching, sodium bicarbonate and aluminum oxide blasting, stone and burs. A Universal Instron Machine was used to apply an occlusal shear force directly to the resin composite bracket surface at a speed of 0.5 mm/min. The means were compared using analysis of variance and multivariate regression to assess the interaction between composites and surface treatment methods. RESULTS Means and standard deviations for the groups were: Sodium bicarbonate jet 11.27 ± 2.78; burs 9.26 ± 3.01; stone 7.95 ± 3.67; aluminum oxide blasting 7.04 ± 3.21; phosphoric acid 5.82 ± 1.90; hydrofluoric acid 4.54 ± 2.87, and without treatment 2.75 ± 1.49. An increase of 1.94 MPa in shear bond strength was seen in Charisma groups. Silane agent application reduced the Charisma shear bond strength by 0.68 Mpa, but increased Durafill means for bicarbonate blasting (0.83), burs (0.98) and stone drilling (0.46). CONCLUSIONS The sodium bicarbonate blasting, burs and stone drilling methods produced adequate shear bond strength and may be suitable for clinical use. The Charisma micro hybrid resin composite showed higher shear bond means than Durafill micro particle composite.

Diagnóstico de má oclusão de Classe III por alunos de graduação

AIM: The aim of this article was to check the ability of undergraduate students to identify Class III malocclusion and also recognize the correct timing for referring them for orthodontic treatment, taking into consideration the patients dental and skeletal ages. METHODS: The sample included 138 senior students of 10 Dental Schools in the State of Rio de Janeiro, which answered a written questionnaire with objective questions. It was also presented to them the facial photographs and study models of a unilateral Class III patient, which also included other dental irregularities. RESULTS: It could be observed that it was easy for most of the students to identify the dental midline deviation (n = 124 or 90%) and the anterior crossbite (n = 122 or 89%). However, approximately half of the sample (n = 63 or 46% of the students) was able to classify the studied clinical case as a unilateral Class III. Only 46% of the group (n = 63) could identify the early loss of a deciduous tooth. Almost the totality of the sample agreed on the orthodontic treatment need, however, it was hard for them to agree on the best timing for referring the case to the specialist and the beginning of this therapy. CONCLUSION: The students graduate in Dental School with difficulties on the correct diagnosis of Class III cases and are not fully aware of a basic protocol for the treatment of this abnormality.

Assessment of the orthodontic knowledge demonstrated by dental school undergraduates: recognizing the key features of Angle Class II, Division 1 malocclusion

OBJECTIVE: To investigate the ability of undergraduate students in diagnosing Angle Class II malocclusion and evaluate the clinical approach of these students toward a patient displaying this condition. METHODS: The sample consisted of 138 students attending the last semester of 10 dental schools in the State of Rio de Janeiro/Brazil assessed by questionnaires with closed questions. They were presented with photographs and dental casts of a patient in the mixed dentition, with Angle Class II malocclusion, increased overjet and overbite, deviated dental midlines and anterior diastemas in the upper arch. RESULTS: It was found that students easily identified increased overjet (92% of students), followed by the presence of diastemas (89%), midline deviation (84.7%) and increased overbite (77.3%). Conversely, approximately half the sample (n=70 or 51% of the students) were able to identify bilateral Angle Class II malocclusion. Nearly all agreed on the need for treatment and that it should be provided by a specialist (n=131 or 95%), but found it difficult to determine the ideal moment to start orthodontic treatment: 48.9% of the sample would begin treatment at the end of the mixed dentition, 41.7% would indicate treatment during deciduous dentition and 7.9% during permanent dentition. CONCLUSIONS: On completion of their undergraduate courses, students encounter difficulties in diagnosing Class II and even find it hard to articulate ideas about a basic treatment protocol to correct this malocclusion.

A correção da mordida cruzada posterior unilateral com desvio funcional melhora a assimetria facial

OBJETIVO: avaliar, atraves de fotografias clinicas de 30 pacientes, as alteracoes ocorridas na assimetria labial presente em pacientes portadores de mordida cruzada posterior unilateral funcional (MCPUF), apos a correcao ortodontica. METODOS: para quantificar essas modificacoes, foram mensuradas as areas dos quadrantes labiais antes (T1) e apos o tratamento (T2). Os labios superiores e inferiores foram subdivididos em 4 quadrantes e as suas areas foram medidas e expressas como percentagem da sua area total. A quantidade de correcao da assimetria foi obtida calculando a diferenca no percentual da area entre os quadrantes do labio em T1 e T2. RESULTADOS: os resultados demonstraram haver uma melhora significativa na assimetria observada inicialmente nestes pacientes do lado onde o desvio postural da mandibula se apresentava.