Evaluation of frictional forces in vitro between brackets and orthodontic wires in upper cusp distalization according to the Tweed-Merrifield Sequential Directional Force Technique

Orientador: Maria Beatriz Borges de Araujo MagnaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo desse estudo foi avaliar in vitro a força de atrito gerada na mecânica de distalização do canino superior pelo uso do gancho ¿J¿ na Técnica da Força Direcional Seqüencial de Tweed-Merrifield, de acordo com as variáveis: tipo e marcas dos braquetes; espessura e marcas dos fios; técnica de amarração e análise das superfícies dos fios e braquetes em microscopia eletrônica de varredura, microscopia de força atômica, além de rugosímetro. Foram utilizados 192 braquetes Edgewise de aço inoxidável de dois tipos e duas marcas comerciais e duas marcas de fios ortodônticos (Morelli, Sorocaba, São Paulo, Brasil e GAC, Central Islip, Nova Iorque, EUA) de aço inoxidável em quatro espessuras, amarrados por ligadura metálica e elastomérica em meio seco e à temperatura ambiente. Foi utilizada uma placa de acrílico retangular simulando um segmento de aparelho fixo composto por quatro braquetes duplos. Cada fio a ser testado teve suas extremidades dobradas justas aos braquetes terminais para que não deslizasse na canaleta e foi amarrado aos braquetes com ligadura de aço inoxidável. A placa de acrílico juntamente com o segmento do fio montado foi fixada no mordente da base da máquina de ensaio universal Instron 4411 (Instron Ltd., High Wycombe, Bucks, Reino Unido) de maneira a ficar posicionada em 45° em relação ao solo, o que foi realizado com o auxílio do esquadro, simulando a angulação do aparelho extrabucal gancho ¿J¿ com o plano oclusal, durante a mecânica de distalização do canino superior. O braquete foi puxado a velocidade de 0,5mm/minuto através do segmento do fio por uma distância de 5mm. Os testes foram repetidos três vezes, trocando-se a combinação braquete/fio a ser testada para cada três grupos. Os valores médios foram obtidos e a força de atrito foi calculada. Após o recorte das canaletas dos braquetes e limpeza dos fios e braquetes, esses foram analisados em microscopia eletrônica de varredura e de força atômica. Além disso, sobre a superfície dos fios foi efetuada a leitura da rugosidade de superfície em micrometros. Os dados foram submetidos à Análise de Variância e ao teste de Tukey (5%). Concluiu-se que: os braquetes duplos proporcionaram maior atrito do que os braquetes simples; os braquetes e fios da marca Morelli proporcionaram maior atrito do que os da GAC; quanto maior a espessura dos fios, maior foi o atrito; a técnica de amarração que gerou maior atrito foi com ligadura elástica quando comparada à ligadura de aço inoxidável; a rugosidade do fio diminuiu com o uso em alguns casos e os fios da marca GAC apresentaram qualitativamente lisura de superfície superior ao da marca MorelliAbstract: This study aimed to evaluate in vitro frictional forces that result from upper cusp distalization due to using the J-Hook, according to the Tweed-Merrifield Sequential Directional Force technique; variables were: bracket type and manufacturer, wire diameter and manufacturer, ligation method and microscopic surface analysis of brackets and wires. One hundred and ninety-two stainless steel Edgewise brackets, of two different types and manufacturers were used, ligated to orthodontic wires of four diameters and two manufacturers (Morelli, Sorocaba, São Paulo, Brazil and GAC, Central Islip, New York, USA) by means of metallic and elastomeric ligatures, at extraoral environment and ambient temperature. A rectangular acrylic plate was manufactured, imitating a fixed appliance section of four double brackets. The ends of each wire were tightly bended to the terminal brackets, in order to eliminate sliding, and were fixed to the brackets by stainless steel ligatures. Each sample, comprising the acrylic plate, as well as the bracket and wire section, was fixed unto a Instron 4411 testing machine (Instron Ltd., High Wycombe, Bucks, United Kingdom), so that each of them was at a 45º inclination, relative to the horizontal plane, thus imitating the extraoral position of the J-hook, relative to the occlusal plane, during upper cusp distalization. The bracket was pulled for 5mm sliding at a speed of 0.5mm/minute. Tests were performed other three times, each for a different bracket/wire combination, over the three groups. The mean values were obtained and frictional forces were calculated. After cutting bracket slots and cleaning wires and brackets, these were analyzed by scanning electron and atomic force microscopy. Also, surface rugosity, in micrometers, was evaluated. Data underwent Variance analysis and Tukey test (5%). Final observations were: twin brackets provide greater frictional forces; brackets and wires manufactured by Morelli showed greater frictional forces than those by GAC; the larger the wire diameter, the greater the frictional forces; elastomeric ligatures resulted in greater friction than stainless steel ligatures; usage made the wires less roughness just in some cases, and GAC manufactured wires presented greater surface smoothness than those by MorelliDoutoradoOrtodontiaDoutor em Radiologia Odontológic

The orthodontist’s civil responsibility post-orthodontic therapy

Objective: The aim of this work was to investigate what the orthodontist’s difficulties are, analyzing whether the adopted procedures are able to satisfy the complaints of individuals, who already concluded orthodontic therapy, according to the determinations of the civil code and the Costumer’s Defense Code, as well as the relationship between patient and professional. Methods: A questionnaire was sent by postal service to all the odonthology specialists inrolled in the CRO/RJ amounting to 990 professionals.Results: The percentual analysis of the analysis showed that 96.9% of them adopt some pattern of kind of contract. The majority (65.8%)regards the orthodontist’s Civil Responsibility as a result. In case of reincident postrentation, 87.2% of the professionals inform the individual that it’s possible and also propose them orthodontic re-treatment. Concerning the conduct adopted by the orthodontist towards the individual’s dissatisfaction, 76.5%, anyhow, try to avoid a lawsuit. Conclusion: Some professionals may be subject to future court problems, there was wide divergence between professionals in relation to the time of filing of the orthodontic documentation and there was a relative same opinion of professionals in making an oversight of the patient in the period post-restraint

Knoop hardness of enamel and shear bond strength of brackets bonded with composite resin with and without fluoride

OBJECTIVE: The aim of this study was to evaluate the Knoop hardness of enamel, shear bond strength and failure pattern (adhesive, bracket/resin interface or mixed) after bonding and debonding brackets, using resin composite with fluoride (Ortho Lite Cure, Ortho Source®) and without fluoride (Orthobond, Morelli®). METHODS: Fragments (6 mm x 6 mm) of 40 bovine incisor crowns were embedded in acrylic self-polymerizing resin. The Knoop hardness measurements were performed before and after bonding metal brackets. The specimens were divided into two groups, according to composite resin: with fluoride (Ortho Lite Cure, Ortho Source®) and without fluoride (Orthobond, Morelli®). After bonding, the specimens were submitted to demineralization and remineralization cycling for 14 days. Shear bond strength testing was performed in a universal test machine (EMIC), at 5 mm/min crosshead speed. RESULTS: There was no significant difference in shear bond strength between Groups I and II. After demineralization and remineralization procedures (DE/RE), the specimens bonded with Ortho Lite Cure showed higher Knoop hardness than Orthobond. For both groups there was predominance of failure at bracket/resin interface. CONCLUSION: specimens bonded with fluoride resin composite showed higher microhardness after DE/RE cycling than those bonded with resin composite without fluoride, although no difference in shear bond strength was found

Nasolabial Angle In Finger Sucking Patients

The purpose of this study is to analise the nasolabial angle and other cephalometric measurements that express the anteroposterior relationship of maxilla and mandibule in individuals with finger sucking habit. Thirty lateral cephalograms were selected from the patient files of the scientific documentation service, Orthodontic Graduation Course of the Piracicaba College of Dentistry, FOP/UNICAMP. The selection criteria was white Brazilian female subjects, 7 to 10 years old, in the phase of mixed dentition, and presenting finger sucking habit. The observed cephalometric measurements were: nasolabial angle, SNA, SNB, ANB, 1.NA, 1-NA and Nperp-A. The results were compared using Student’s ‘t’ test and, significance level of 5% (á = 0,05). The analysis showed no differences in the nasolabial angle in subjects presenting finger sucking habit; the maxilla and mandibule was well positioned, relative to the cranial base, and the upper incisors were well positioned.414798-80

Cephalometric Evaluation Of Class Iii Malocclusion By A Modified Tweedmerrifield Analysis

A sample of cephalograms of 20 White Brazilian subjects (9 males, 11 females) of 17-36 years old, who presented Class III dental malocclusion was selected and traced. Results showed statistically significant differences among genders for FMIA, SNA, SNB, 1.NB, PFH, AFH, 1-NB and mandibular length. Anteroposterior jaw relation, as shown by SNA and SNB, presented a maxilla correctly positioned, as well as mandibular protrusion, which was related to a normal upper jaw length and an augmented lower jaw length. A vertical growth pattern prevailed, as evidenced by FMA, AFH, PHF and OCC.PL. Angle. The Z Angle, total chin and upper lip failed to clearly show any disturbance of facial esthetics and IMPA, 1.NA, 1- NA, 1.NB and 1-NB revealed dental compensation.412680-68

Relationship between posterior crossbite and postural alterations in children

Objective: To evaluate the posture of individuals with functional posterior crossbite, malocclusion is one of the most in need of orthodontic treatment. Methods: This work presents an analysis of postural among children 6 to 12 years who present functional posterior cross bite of both genders who are in mixed dentition or no intervention prior orthodontic and orthopedic. Was obtained images in the plans: front and back where it was analyzed the asymmetry or symmetry of the individual in the image and in the lateral, anterior, a posterior or normality. Results: 100% had some kind of postural change, and the asymmetry between the scapulae (shoulder) found the greatest change, as one of extreme importance in this age group represents a growing skeletal muscle. Conclusion: analyzes all of the children showed postural abnormalities and malocclusion are also of great importance not only to be treating the problem orally, but the postural problem with the help of a multidisciplinary team

Analysis of Tweed’s Facial Triangle in Black Brazilian youngsters with normal occlusion

A cephalometric study was carried on a sample of 37 Black youngsters of both genders (16 males, 21 females), descending from Black Brazilian parents or grandparents, age varying from 10 to 14 years, from the city of Piracicaba, Brazil, and all of them with normal occlusion. None of them has ever undergone orthodontic treatment. This study aimed to ascertain the mean values for the cephalometric measures which take part on the Tweed's Facial Triangle: FMA, FMIA and IMPA, and we also tried to verify the occurrence of sexual dimorphism in this ethnic group. Statistical analysis (Student's test, 5%) of the results show that this ethnic group presented lower incisors with greater inclination and a more convex facial profile, but no sexual dimorphism

Evaluation of enamel roughness after ceramic bracket debonding and clean-up with different methods

Aim: This study evaluated the surface roughness (Ra) and the topography (scanning electron microscopy) of the dental enamel after use of different methods for removal of residual resin after debonding of orthodontic brackets. Methods: Nine roughness measurements in three directions were made on enamel surface of 60 human premolars before bracket bonding (Ra initial). Ceramic brackets were bonded with Transbond XT and stored for 24 h/37°C before debonding with pliers. The specimens were divided in five groups according to the method used for removal of residual resin: control (C); carbide bur at slow-speed (CL); carbide bur at high speed (CH); Shofu tip at low speed (SB); Shofu tip at high speed (HB); debonding pliers (ZP). Nine final surface roughness measurements (Ra final) were made and one specimen of each group was observed by SEM. The data were analyzed statistically by ANOVA, Tukey′s test and paired t test (p<.05). Results: Ra final of SB was significantly higher than C, CL, CH, and ZP groups. The t-test showed that the Ra final was significantly higher than Ra initial for SB and CL. Conclusions: The method used for removal of residual resin influenced the roughness of the enamel. Carbide bur at high speed presented the best results and Shofu at low speed presented the worst results