Júlio de Araújo Gurgel

Debris, roughness and friction of stainless steel archwires following clinical use.

OBJECTIVE To investigate the degree of debris, roughness, and friction of stainless steel orthodontic archwires before and after clinical use. MATERIALS AND METHODS For eight individuals, two sets of three brackets (n = 16) each were bonded from the first molar to the first premolar. A passive segment of 0.019- x 0.025-inch stainless steel archwire was inserted into the brackets and tied by elastomeric ligature. Debris level (via scanning electron microscopy), roughness, and frictional force were evaluated as-received and after 8 weeks of intraoral exposure. Mann-Whitney, Wilcoxon signed-rank, and Spearman correlation tests were used for statistical analysis at the .05 level of significance. RESULTS There were significant increases in the level of debris (P = .0004), roughness of orthodontic wires (P = .002), and friction (P = .0001) after intraoral exposure. Significant positive correlations (P < .05) were observed between these three variables. CONCLUSION Stainless steel rectangular wires, when exposed to the intraoral environment for 8 weeks, showed a significant increase in the degree of debris and surface roughness, causing an increase in friction between the wire and bracket during the mechanics of sliding.

Ossification of the midpalatal suture after surgically assisted rapid maxillary expansion

The purpose of this study was to evaluate ossification of the midpalatal suture in adult patients immediately after surgically assisted rapid maxillary expansion (SARME) until 120 days post-surgery. The sample comprised 126 standardized occlusal radiographs of 21 adults (14 females and 7 males; mean age: 25.33 years) taken pre-expansion (T1), immediately after expansion (T2), and post-expansion (30, 60, 90, and 120 days of retention, respectively: T3, T4, T5, and T6) who had undergone SARME. The radiographs were digitized and the images were analysed and compared in relation to the morphology and radiopacity at the different treatment stages, especially concerning the characteristics of the midpalatal suture. Data were statistically analysed using analysis of variance and Tukeys test. The results demonstrated that from T2 to T6, the mean optical density (OD) increased. However, these values were not similar to those observed at T1. A retention period of 120 days was not sufficient for the re-establishment of OD and complete ossification within the suture in the evaluated patients.

Mechanical properties of beta-titanium wires

OBJECTIVE To evaluate the force-deflection behavior of six beta-titanium wires using a three-point bending test. MATERIALS AND METHODS The wires timolium (TIM), titanium molybdenum (ORG), beta titanium (BETA), resolve (RES), titanium molybdenum alloy (TMA), and TMA low friction (TMAL) were adapted into two stainless steel brackets, with no angulation or torque. Both brackets were bonded to an acrylic jig with a 10-mm interbracket distance. A testing machine (Instron) applied deflections of 0.2 to 2.0 mm. Force-deflection diagrams were determined from a passive position to an activation of 2 mm and then during deactivation. Forces of activation and deactivation at a deflection of 1 mm were compared by analysis of variance. RESULTS Results demonstrated that significant differences (P < .05) in force were observed among wires. During activation, forces for the wires were ranked from lowest to highest as TMAL = TMA = RES<ORG = BETA<TIM. During deactivation, forces for the wires were ranked from lowest to highest as TIM<ORG = BETA<RES =  TMA<TMAL. The wires exhibited similar activation-deactivation diagrams. CONCLUSION This study revealed significant differences in force during activation and deactivation among the six types of beta-titanium wires tested.

O uso de marcadores para identificação de posicionamento dentário em telerradiografias frontais póstero-anteriores: proposta de um método

AIM: to evaluate the reliability in the identification of the markers observed in frontal Cephalometric x-rays. METHODS: in 3 dry humans skull were adapted expansor appliances, in which markers were attached at orthodontics brackets and tubes. RESULTS: the statistical comparison of the 27 postero-anterior cephalograms revealed that the angular measures showed small variations; however the smallest error were for the lineal measures among the markers. CONCLUSION: the markers demonstrated its reliability for the use in longitudinal researches with frontal cephalometric x-rays.

Estudo in vitro da resistência ao cisalhamento da colagem direta de tubos ortodônticos em molares

OBJECTIVE: Although direct bonding takes up less clinical time and ensures increased preservation of gingival health, the banding of molar teeth is still widespread nowadays. It would therefore be convenient to devise methods capable of increasing the efficiency of this procedure, notably for teeth subjected to substantial masticatory impact, such as molars. This study was conducted with the purpose of evaluating whether direct bonding would benefit from the application of an additional layer of resin to the occlusal surfaces of the tube/tooth interface. METHODS: A sample of 40 mandibular third molars was selected and randomly divided into two groups: Group 1 - Conventional direct bonding, followed by the application of a layer of resin to the occlusal surfaces of the tube/ tooth interface, and Group 2 - Conventional direct bonding. Shear bond strength was tested 24 hours after bonding with the aid of a universal testing machine operating at a speed of 0.5mm/min. The results were analyzed using the independent t-test. RESULTS: The shear bond strength tests yielded the following mean values: 17.08 MPa for Group 1 and 12.60 MPa for Group 2. Group 1 showed higher statistically significant shear bond strength than Group 2. CONCLUSIONS: The application of an additional layer of resin to the occlusal surfaces of the tube/tooth interface was found to enhance bond strength quality of orthodontic buccal tubes bonded directly to molar teeth.

Avaliação radiográfica da localização de caninos superiores não irrompidos

A erupcao ectopica e a impaccao de caninos superiores sao problemas bastante comuns na populacao. A excelencia do tratamento ortodontico traduz-se na correcao da oclusao, harmonia do sorriso, saude periodontal e estabilidade pos-tratamento. Para obtermos tais condicoes, a manutencao dos caninos e fundamental. Portanto, o objetivo deste estudo foi avaliar radiograficamente a localizacao de caninos superiores nao irrompidos utilizando-se radiografias panorâmicas. Foram selecionadas setenta radiografias panorâmicas de pacientes com impaccao uni ou bilateral de caninos, candidatos a tratamento cirurgico. Para determinacao da posicao espacial dos caninos superiores nao irrompidos foram selecionados metodos descritos na literatura e uma avaliacao proposta neste trabalho. A localizacao de caninos nao irrompidos e fundamental para estabelecer o plano de tratamento, auxiliando no acesso cirurgico e na direcao das forcas ortodonticas a serem aplicadas no dente impactado. Os pacientes que tiveram suas radiografias utilizadas neste estudo serao tratados pelas disciplinas de Ortodontia e Cirurgia, com exodontia do canino ou exposicao cirurgica para colagem do dispositivo de tracionamento associada ao tratamento ortodontico corretivo.

Clinical Efficiency of Two Sequences of Orthodontic Wires to Correct Crowding of the Lower Anterior Teeth.

This study compared time to correction of mandibular anterior crowding using two arch wire sequences, one with conventional nickel-titanium (NiTi) arch wires and the other with conventional and NiTi heat-activated arch wires. Twenty-two boys and girls (mean age: 16.68 ± 2.66) with moderate crowding (3-6 mm) were assigned randomly to one of two groups and followed up for five months (six assessments) when arch wires were changed. Time to crowding correction was analyzed statistically using the Kaplan-Meier method. Data were collected during the five-month follow-up, and time to correction was compared between groups using the log rank test. At the end of follow-up, mandibular crowding was corrected in 100% of the cases in the group treated with the sequence that included NiTi heat-activated arch wires, whereas about 30% of those treated with NiTi arch wires were not completely corrected. There was a significant difference in time to complete treatment between groups (log rank = 5.996; p < 0.05). In the group treated with the sequence that included heat-activated wires, alignment and leveling of mandibular anterior teeth were completed earlier than in the group treated only with conventional NiTi arch wires. Clinical trial registration is found at RBR-7g5zng.This study compared time to correction of mandibular anterior crowding using two arch wire sequences, one with conventional nickel-titanium (NiTi) arch wires and the other with conventional and NiTi heat-activated arch wires. Twenty-two boys and girls (mean age: 16.68 ± 2.66) with moderate crowding (3–6 mm) were assigned randomly to one of two groups and followed up for five months (six assessments) when arch wires were changed. Time to crowding correction was analyzed statistically using the Kaplan-Meier method. Data were collected during the five-month follow-up, and time to correction was compared between groups using the log rank test. At the end of follow-up, mandibular crowding was corrected in 100% of the cases in the group treated with the sequence that included NiTi heat-activated arch wires, whereas about 30% of those treated with NiTi arch wires were not completely corrected. There was a significant difference in time to complete treatment between groups (log rank = 5.996; p < 0.05). In the group treated with the sequence that included heat-activated wires, alignment and leveling of mandibular anterior teeth were completed earlier than in the group treated only with conventional NiTi arch wires. Clinical trial registration is found at RBR-7g5zng.

Mini-implants as provisional anchorage for the replacement of missing anterior teeth: A clinical report

This clinical report describes an adult patient referred for orthodontic treatment with mini-implants as anchorage to correct the root angulation of maxillary lateral incisors. The purpose of this report was to demonstrate the versatility of mini-implants placed in a vertical direction in esthetic areas. During orthodontic treatment, some aspects must be observed to preserve the interim restoration against the occlusal loads to avoid screw fracture. A fixed appliance was placed to correct the position of the maxillary anterior teeth and to complete the treatment. Acceptable esthetics and function were achieved.

Cirurgia ortognática de modelos: protocolo para mandíbula

INTRODUCTION: The cast surgery has great importance in orthognatic surgery treatment planning. AIM: In this article, a step by step lower model surgery will be presented, emphasizing important details and advantages of this procedure.

Effect of vertical placement angle on the insertion torque of mini-implants in human alveolar bone

ABSTRACT Objective: The aim of the present ex-vivo study was to evaluate the effect of the vertical placement angle of mini-implants on primary stability by analyzing maximum insertion torque (MIT). Methods: Mini-implants were placed in 30 human cadavers, inserted at either a 90° or 60° angle to the buccal surface of the maxillary first molar. Out of 60 self-drilling mini-implants used, half were of the cylindrical type and half were of the conical type. Primary stability was assessed by means of measuring the MIT. Data were subjected to analysis of variance (ANOVA) and Newman-Keuls tests. A significance level of 5% was adopted. Results: The MIT was higher for both mini-implant types when they were placed at a 90° angle (17.27 and 14.40 Ncm) compared with those placed at a 60° angle (14.13 and 11.40 Ncm). Conclusions: MIT values were differed according to the vertical mini-implant placement angle in the maxillary posterior area. Regardless of the type of mini-implant used, placement at a 90° angle resulted in a higher MIT.