Effect of different fabrication methods of occlusal devices on periradicular stress distribution: A photoelastic analysis.

STATEMENT OF PROBLEM: Investigations on the effectiveness of new methods for optimizing the fabrication of oral devices are lacking. PURPOSE: The purpose of this in vitro study was to evaluate stress distribution with photoelastic analysis in the periradicular area of teeth supporting occlusal devices fabricated by 5 different processes. MATERIAL AND METHODS: The occlusal devices were fabricated by vacuum thermoforming, heat-polymerized acrylic resin, chemical polymerized acrylic resin, 3-dimensional printing, and milling (computer-aided manufacturing). The devices were evaluated regarding initial fit, number of adjustments for passive fit, and stress distribution under 100-N and 400-N loads in the periradicular locations of posterior teeth. RESULTS: The 3-dimensional printing device did not require any adjustment for initial adaptation to the photoelastic model and presented a little friction with the model. The heat-polymerized acrylic resin device did not seat initially, requiring more sites of adjustment until passive adaptation. At 100-N and 400-N loads, the use of the computer-aided manufacturing occlusal device resulted in the lowest stresses in periradicular areas (0.744 and 1.583, respectively), and the 3-dimensional printing occlusal device produced the highest stresses with a 400-N load application (2.427). The lowest mean of fringe pattern was observed for the computer-aided manufacturing device, and the highest mean of fringe pattern was observed for the vacuum thermoforming device. CONCLUSIONS: The computer-aided design and computer-aided manufacturing milled occlusal device presented the best initial adaptation and transferred lower stresses to the periradicular areas than the other evaluated devices.

Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane.

INTRODUCTION:: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. METHODS:: Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. RESULTS:: Significant statistical differences (p< 0.05) for surface roughness and bacterial adhesion reduction were observed on conventional brackets after surface treatment and between conventional and self-ligating brackets; no significant statistical differences were observed between self-ligating groups (p> 0.05). CONCLUSION:: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.

Analysis of residual stress and hardness in regions of pre-manufactured and manual bends in fixation plates for maxillary advancement.

The aim of this study was to analyze, through Vickers hardness test and photoelasticity analysis, pre-bent areas, manually bent areas, and areas without bends of 10-mm advancement pre-bent titanium plates (Leibinger system). The work was divided into three groups: group I-region without bend, group II-region of 90° manual bend, and group III-region of 90° pre-fabricated bends. All the materials were evaluated through hardness analysis by the Vickers hardness test, stress analysis by residual images obtained in a polariscope, and photoelastic analysis by reflection during the manual bending. The data obtained from the hardness tests were statistically analyzed using ANOVA and Tukey's tests at a significance level of 5 %. The pre-bent plate (group III) showed hardness means statistically significantly higher (P < 0.05) than those of the other groups (I-region without bends, II-90° manually bent region). Through the study of photoelastic reflection, it was possible to identify that the stress gradually increased, reaching a pink color (1.81 δ / λ), as the bending was performed. A general analysis of the results showed that the bent plate region of pre-bent titanium presented the best results.

Stress distribution in the peri-implant area of pure titanium and titanium-zirconium small implants

Aim: In dental implant treatment, there is a demand for mechanically stronger implants. Despite the existence of several studies showing the clinical success of narrow diameter implants, most of them are based on pure titanium (cpTi) alloys. There is a few clinical evidences of the success rate of titanium-zirconium (TiZr) narrow diameter implants. The aim of this study was to evaluate the stress distribution in the peri-implant area of narrow diameter cpTi and TiZr implants under axial and oblique loads. Methods: Photoelastic models were produced using epoxy resin (PL2, Vishay Precision Group) from a master model. The implants (cpTi and TiZr; Straumann AG) had 3.3 mm in diameter and 12 mm in height. Loads of 100 N and 200 N were applied to the abutment at angles of 0° (axial), 10°, 20°, and 30° (oblique). A circular polariscope (Eikonal) was used under dark field white-light configuration. The isochromatic fringes were analyzed in the peri-implant region in 5 areas, using ASTM table with isochromatic fringes; cervical-mesial, cervical-distal, mid-mesial, mid-distal and apical. Results: In general, under axial and oblique loads, the stress in the TiZr implant was lower than in the cpTi implant. The load of 200 N produced the highest stress values in cpTi and TiZr implants. In both implants and loads, the fringes were located more in apical area at all angles evaluated. Conclusion: It can be concluded that for small implants, the load inclination and intensity change the pattern of stress distribution and the cpTi implant exhibited the highest peri-implant stress

Influence of bone loss and inclination of incisor on periradicular stresses due to simulated bite force / Influência da perda óssea e da inclinação do incisivo na distribuição de tensões perirradiculares decorrentes da simulação de forças oclusais

Introduction: Adults with sequelae of periodontal disease tend to have bone loss, with consequent flaring of the maxillary incisors. Objective: The influence of bone loss and the inclination of the maxillary incisor in the distribution of stresses due to simulated bite forces was studied. Material and method: Models in epoxy resin were made in three conditions (without bone loss and with bone loss of 5mm and 8mm). Increases in the labial inclination of the maxillary incisor of 10° and 20° were obtained with a beveled metallic block. Loads of 100N were applied five times in each condition using a universal test machine. The models were observed and filmed with a circular polariscope. Orders of isochromatic fringes (stresses) on the labial, lingual, and apex surfaces were recorded. The agreement of the data was evaluated using the weighted kappa test, and the results were 0.89 and 0.82 for intra- and inter-examiners, respectively. Result: The results of the Kruskal-Wallis and SNK tests indicated higher stresses (2.0) with increased labial inclination in the labial surface; higher stresses (2.67) with increased bone loss; higher greater stresses with the association of bone loss and labial-inclination (3.6); and the highest stresses tended to concentrate on the labial surfaces, except in cases of normal inclination and without bone loss (0.45). Conclusion: It was concluded that increases in both the labial inclination of the maxillary incisors and bone loss increase periradicular stresses, and the combination of these factors further increases the stresses due to bite forces, with the highest concentration on the labial side.

Introdução: Adultos com sequelas de doenças periodontais tendem a apresentar perda óssea, com consequente vestibularização dos incisivos superiores. Objetivo: A influência da perda óssea e da inclinação do incisivo superior na distribuição de tensões devido a forças mastigatórias simuladas foram avaliadas nesse estudo. Material e método: Modelos em resina epóxi foram confeccionados em três condições (sem perda óssea e com perda óssea de 5mm e 8mm). Aumentos na inclinação vestibular do incisivo superior de 10° e 20° foram obtidos com um bloco metálico chanfrado. Cargas de 100N foram aplicadas cinco vezes em cada condição usando uma máquina de ensaio universal. Os modelos foram observados e filmados com um polariscópio circular. Ordens de franjas isocromáticas (tensões) nas faces vestibular, lingual e apical foram registradas. A concordância dos dados foi avaliada pelo teste kappa ponderado e os resultados foram 0,89 e 0,82 para intra e interexaminadores, respectivamente. Resultado: Os resultados dos testes de Kruskal-Wallis e SNK indicaram maiores tensões (2,0) com aumento da inclinação vestibular na face vestibular; maiores tensões (2,67) com aumento da perda óssea; maior tensão com a associação de perda óssea e inclinação vestibular (3,6); e as maiores tensões tenderam a concentrar-se na face vestibular, exceto em casos de inclinação normal e sem perda óssea (0,45). Conclusão: Concluiu-se que aumentos tanto da inclinação vestibular dos incisivos superiores quanto da perda óssea aumentam as tensões perirradiculares, e a combinação desses fatores aumenta ainda mais as tensões devido às forças mastigatórias, com a maior concentração na face vestibular.

Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane

ABSTRACT Introduction: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods: Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results: Significant statistical differences (p< 0.05) for surface roughness and bacterial adhesion reduction were observed on conventional brackets after surface treatment and between conventional and self-ligating brackets; no significant statistical differences were observed between self-ligating groups (p> 0.05). Conclusion: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.

RESUMO Introdução: a deposição de filme de polímero a plasma foi criada para modificar as propriedades de superfície dos braquetes ortodônticos metálicos, com o intuito de inibir a adesão bacteriana. Métodos: filmes finos de polímero de hexametildisiloxano (HMDSO) foram depositados em braquetes ortodônticos de aço inoxidável convencionais (n = 10) e autoligáveis (n = 10), utilizando a técnica de radiofrequência PECVD (Plasma-Enhanced Chemical Vapor Deposition). As amostras foram divididas em dois grupos, de acordo com o tipo de braquete, e dois subgrupos após o tratamento de superfície. A microscopia eletrônica de varredura (MEV) foi realizada para avaliar a presença de adesão bacteriana sobre as superfícies das amostras (região de ranhura horizontal e aletas) e a integridade da camada de filme. A Interferometria Confocal (CI) avaliou a rugosidade, e a molhabilidade superficial foi avaliada por goniometria. Para análise de adesão bacteriana, as amostras foram expostas durante 72 horas a uma solução de Streptococcus mutans, para formação de biofilme. Os valores obtidos para a rugosidade da superfície foram analisados pelo teste de Mann-Whitney, enquanto a adesão do biofilme foi avaliada pelos testes de Kruskal-Wallis e SNK. Resultados: observaram-se diferenças estatisticamente significativas (p <0,05) para a rugosidade superficial e redução da adesão bacteriana em braquetes convencionais após o tratamento da superfície, e entre braquetes convencionais e autoligáveis. Não foram observadas diferenças estatísticas significativas entre os grupos autoligáveis (p> 0,05). Conclusão: a deposição de polímero a plasma só foi efetiva na redução da rugosidade superficial e adesão bacteriana em braquetes convencionais. Observou-se, também, que os braquetes convencionais apresentaram menor adesão ao biofilme do que os braquetes autoligáveis, apesar da ausência de filme.

Analysis of stress in the walls of simulated artificial root canals during instrumentation with reciproc system: a pilot study using a photoelastic model / Análise de estresse nas paredes de canais artificiais simulados durante a instrumentação com sistema reciproc: um estudo piloto usando um modelo fotoelástico

Objective: The aim of this pilot study was to perform in vitro analysis of the stress related to instrumentation of artificial root canals with Reciproc System by using the photoelasticity method. Material and Methods: Photoelastic models consisted of two epoxy resin blocks simulating root canals, which were attached with cyanoacrylate adhesive to a base and placed at the centre of a circular polariscope in a darkfield configuration. The Reciproc R25 instrument was mounted to a VDW motor and used in block 1 up to 12 mm (working length) and then the same instrument was used in block 2. The images were captured by video camera and analysed at the time of the fourth penetration. Isochromatic fringes were observed in the cervical, middle and apical thirds at mesial and distal regions of each block. Therefore, they were divided into cervical-mesial (CM), cervicaldistal (CD), middle-mesial (MM), middle-distal (MD), apical-mesial (AM) and apical-distal (AD). Results: In the first instrumentation, it was found that the greatest stress occurred at the middle-distal region (1.38), followed by middle-mesial (1.20), apicaldistal (1.20) and apical-mesial regions (1.20). In the second instrumentation, the greatest stress occurred at the middle-mesial (1.20), apical-distal (1.20), apical-mesial (1.20) and middle-distal regions (0.90). Conclusion: The greatest stress occurred in the middle and apical thirds during the first instrumentation. Reutilization caused less stress.

O objetivo deste estudo piloto foi realizar a análise in vitro do estresse relacionado a instrumentação de canais artificiais utilizando o sistema de instrumentação Reciproc por meio da fotoelasticidade. Material e Métodos: Modelos fotoelásticos de dois blocos de resina epóxi com um canal simulado foram fixados com adesivo de cianoacrilato sobre uma base no centro de um polariscope circular na configuração de campo escuro. O instrumento Reciproc R25 foi inserido no motor VDW e utilizado no bloco 1 até 12 mm (comprimento de trabalho) e, sem seguida, o mesmo instrumento foi utilizado no bloco 2. As imagens foram captadas pela câmara de vídeo e analisadas no tempo da quarta penetração. As franjas isocromáticas foram observadas nos terços cervical, médio e apical, em regiões mesial e distal de cada bloco. Sendo assim, divididos em: CM - cérvico-mesial, CD - cérvicodistal, MM - médio-mesial, MD - médio-distal, AM - apical-mesial e AD - apical-distal. Resultados: Na primeira utilização do instrumento, o maior estresse ocorreu na região médio-distal (1,38), seguido por médio-mesial (1,20), apical-distal (1,20) e apicalmesial (1,20). No segundo uso, o maior estresse ocorreu na região médio-mesial (1,20), apical-distal (1,20), apical-mesial (1,20) e médio-distal (0,90). Conclusão: O maior estresse ocorreu nos terços médio e apical na primeira utilização, sendo que a reutilização promoveu menos estresse.

Association between overbite and craniofacial growth pattern.

The purpose of the present study was to assess the association between overbite and craniofacial growth pattern. The sample comprised eighty-six cephalograms obtained during the orthodontic pretreatment phase and analyzed using the Radiocef program to identify the craniofacial landmarks and perform orthodontic measurements. The variables utilized were overbite, the Jarabak percentage and the Vert index, as well as classifications resulting from the interpretation of these measurements. In all the statistical tests, a significance level of 5% was considered. Measurement reliability was checked by calculating method error. Weighted Kappa analysis showed that agreement between the facial types defined by the Vert index and the direction of growth trend established by the Jarabak percentage was not satisfactory. Owing to this lack of equivalency, a potential association between overbite and craniofacial growth pattern was evaluated using the chi-square test, considering the two methods separately. No relationship of dependence between overbite and craniofacial growth pattern was revealed by the results obtained. Therefore, it can be concluded that the classification of facial growth pattern will not be the same when considering the Jarabak and the Ricketts anayses, and that increased overbite cannot be associated with a braquifacial growth pattern, nor can openbite be associated with a dolichofacial growth pattern.

Comparative photoelastic study of dental and skeletal anchorages in the canine retraction

OBJECTIVE: To compare dental and skeletal anchorages in mandibular canine retraction by means of a stress distribution analysis. METHODS: A photoelastic model was produced from second molar to canine, without the first premolar, and mandibular canine retraction was simulated by a rubber band tied to two types of anchorage: dental anchorage, in the first molar attached to adjacent teeth, and skeletal anchorage with a hook simulating the mini-implant. The forces were applied 10 times and observed in a circular polariscope. The stresses located in the mandibular canine were recorded in 7 regions. The Mann-Whitney test was employed to compare the stress in each region and between both anchorage systems. The stresses in the mandibular canine periradicular regions were compared by the Kruskal-Wallis test. RESULTS: Stresses were similar in the cervical region and the middle third. In the apical third, the stresses associated with skeletal anchorage were higher than the stresses associated with dental anchorage. The results of the Kruskal-Wallis test showed that the highest stresses were identified in the cervical-distal, apical-distal, and apex regions with the use of dental anchorage, and in the apical-distal, apical-mesial, cervical-distal, and apex regions with the use of skeletal anchorage. CONCLUSIONS: The use of skeletal anchorage in canine retraction caused greater stress in the apical third than the use of dental anchorage, which indicates an intrusive component resulting from the direction of the force due to the position of the mini-implant and the bracket hook of the canine. .

OBJETIVO: comparar as ancoragens dentária e esquelética na retração do canino inferior, por meio do estudo da distribuição de tensões. MÉTODOS: foi confeccionado um modelo fotoelástico de segundo molar a canino, sem o primeiro pré-molar, e simulada a retração do canino inferior com elástico preso a dois tipos de ancoragem: dentária, no primeiro molar conjugado aos dentes adjacentes; e ancoragem esquelética, em gancho simulando o mini-implante. As forças foram aplicadas 10 vezes e observadas no polariscópio circular. As tensões no canino inferior foram registradas em 7 regiões. O teste de Mann-Whitney foi aplicado para comparar as tensões em cada região, considerando os dois sistemas de ancoragem. As tensões nas regiões perirradiculares do canino foram comparadas pelo teste de Kruskal-Wallis. RESULTADOS: as tensões foram similares tanto na região cervical quanto no terço médio. No terço apical, as tensões associadas à ancoragem esquelética foram maiores que as tensões associadas à ancoragem dentária. Os resultados do teste de Kruskal-Wallis mostraram que as maiores tensões foram identificadas nas regiões cervicodistal, apicodistal e na região do ápice com o uso da ancoragem dentária; e com o uso da ancoragem esquelética, as maiores tensões se localizaram nas regiões apicodistal, apicomesial, cervicodistal e no ápice. CONCLUSÃO: o uso de ancoragem esquelética na retração promoveu maior tensão no terço apical do que o uso da ancoragem dentária, indicando um componente intrusivo devido à direção da força decorrente da posição do mini-implante e do gancho do braquete do canino. .

Influência de diferentes aplicaçõesde cargas e interposição de aparelhooclusal plano em implantes dentais:análise fotoelástica / Influence of different loads and interposing of plane occlusalappliance in dental implants: photoelastic analysis

Se forças oclusais excederem a capacidade de absorção do sistema implante/osso, o implante tende a fracassar. O objetivo deste estudo foi avaliar a tensão peri-implantar com e sem utilização de placa oclusal plana sob carregamentos diferentes. Materiais e Métodos: Foram confeccionados cinco modelos fotoelásticos, com um implante em cada. Sobre estes implantes foram instaladas coroas unitárias e construída uma placa oclusal plana. Foram aplicadas cargas axiais de 100N, 200N e 300N, com e sem a presença da placa oclusal plana, por meio da máquina universal de ensaio conjugada ao polariscópio. O teste de Mann-Whitney foi utilizado para comparar os grupos com e sem placa, em todas as condições de carregamento. O teste de Kruskal-Wallis foi utilizado para comparar as tensões decorrentes das cargas de 100, 200 e 300N e também para comparar as tensões nas seis áreas periimplantares analisadas. Resultados: Os resultados dos testes de Mann-Whitney não identificaram diferenças estatísticas (p>0,05) ao comparar as ordens de franjas com e sem a utilização de aparelho oclusal plano, em todas as áreas periimplantares analisadas, sob cargas verticais de 100, 200 e 300N. Os resultados dos testes de Kruskal-Wallis indicaram tensões significativamente maiores nas regiões apicais (p<0,05) e que nas áreas apicais as tensões foram maiores com o carregamento de 300N (p<0,05). Conclusões: A utilização da placa oclusal plana sobre a prótese unitária não reduziu significativamente as tensões nas regiões periimplantares; as tensões tendem a se concentrarem na região periapical e nestas áreas a maior magnitude de força implicou em maior tensão...

Introduction: If occlusal forces exceed the capacity of the implant/bone system, the implant tends to fail. The aim of this study was to evaluate the peri-implant stress with and without use of flat occlusal splint under various loads. Materials and Methods: Five photoelastic models were made with an implant in each. About these implants crowns were installed and built a flat occlusal splint. Axial loads of 100N, 200N and 300N, with and without the presence of the occlusal plane plate, were applied by universal testing machine conjugate to the polariscope. The Mann-Whitney test was used to compare the groups with and without plate, in all conditions of loading. The Kruskal-Wallis test was used to compare the stresses resulting from loads of 100, 200 and 300N and also to compare the peri-implant stresses in the six areas analyzed. Results: The results of Mann-Whitney tests identify no significant differences (p> 0.05) comparing fringe orders with and without the use of flat occlusal appliance, in all peri-implant areas examined under vertical loads 100, 200 and 300N. The results of Kruskal-Wallis tests indicated significantly higher stress in the apical regions (p <0.05) and in the apical areas stresses were higher with the loading of 300N (p <0.05). Conclusions: The use of flat occlusal splint on the unitary prosthesis did not significantly reduce the stress in the peri-implant regions; stress tend to concentrate on the periapical region and in these areas the largest magnitude of force resulted in higher stress...

Forces in stainless steel, TiMolium and TMA intrusion arches, with different bending magnitudes.

The present study compared forces in stainless steel, TiMolium and TMA, V-bend intrusion arches with different magnitudes of flexion. The sample consisted of rectangular-section wires, caliber .017" x .025", with ten arches of each alloy. All V-bends were made 48 mm from the midline, using the same phantom upper jaw, maintaining the same distance between the tubes fixed to the molars and the midline. Loads necessary to deflect the arches by 5, 10, 15 and 20 mm were measured by means of an Instron dynamometer with a 1 kgf load cell. Calculations for sample size confirmed the suitability of using 10 arches of each alloy. Variance tests (ANOVA) of one factor and three levels, complemented by the Tukey test for multiple comparisons, identified that TMA(R) intrusion arches required a smaller quantity of load in relation to conventional steel and TiMolium at all levels of flexion. Furthermore, TiMolium presented intermediary characteristics between steel and TMA, and in all alloys increase in distance entailed a significant increase in force between all registered values, and that the increase in load necessary to deflect the arches at the intervals tended to decrease from first to last interval, these differences being more significant in steel, less in TiMolium and practically non-existent in TMA.

Correlation between transverse expansion and increase in the upper arch perimeter after rapid maxillary expansion.

The purpose of the present study was to assess the correlation between transverse expansion and the increase in upper arch perimeter, after maxillary expansion. Dental casts of eighteen patients were obtained before treatment and again five months after maxillary expansion. Measurements of intermolar width, intercanine width, arch length and arch perimeter were made with a digital caliper on photocopies taken from the dental casts. After assessment of the method error, a multiple regression model was developed following the identification of the best subset of variables. The resulting equation led to the conclusion that the increase in arch perimeter is approximately given by the addition of 0.54 times the intercanine expansion, and 0.87 times the arch length alteration.

Distribuição de tensões em modelo fotoelástico decorrente da intrusão dos incisivos inferiores por meio do arco base de Ricketts / Stress distribution in a photoelastic model resulting from intrusion of mandibular incisors using Ricketts utility arch

OBJETIVO: o presente estudo analisou a distribuição de tensões, em modelo fotoelástico, gerada por arco base de intrusão de incisivos inferiores. Compararam-se as tensões entre os terços radiculares de cada incisivo e, ainda, verificou-se a existência de diferenças de concentrações de tensões entre incisivos. MÉTODOS: foram confeccionados 15 arcos base de intrusão e a força de ativação foi mensurada em 50gf na região da linha média. O modelo fotoelástico foi observado em polariscópio circular, na configuração de campo escuro, e fotografado. As fotografias frontais foram analisadas e as ordens de franjas em cada região registradas. A análise de Kappa ponderado identificou a repetibilidade do método. A comparação entre as tensões foi realizada pelo teste de Kruskal-Wallis complementado com teste de Dunn com nível alfa de 5 por cento. RESULTADOS E CONCLUSÕES: os resultados identificaram que as maiores magnitudes de tensões foram observadas nas regiões cervicais. Ao se comparar as ordens de franjas entre os dentes, as maiores magnitudes de tensões foram observadas nos incisivos centrais. Portanto, a região cervical pode estar mais sujeita a reabsorções, assim como os incisivos centrais, por concentrarem maiores tensões.

OBJECTIVE: This study aimed to investigate stress distribution in a photoelastic model generated by Ricketts Utility Arch (RUA), also known as Ricketts base arch, for intrusion of mandibular incisors. Stresses in the root thirds of each incisor were compared and the existence of differences in the concentration of stresses between the incisors was also examined.METHODS: Fifteen intrusion RUAs were fabricated. Activation force was set at 50 gf in the midline region. The photoelastic model was observed in a circular polariscope in dark field configuration and photographed. Frontal view photographs were analyzed and fringe orders recorded in each region. Weighted Kappa analysis was used to identify method repeatability. Comparison between stresses was performed by Kruskal-Wallis test and complemented by Dunn's test at 5% alpha level.RESULTS AND CONCLUSIONS: Results showed that the major stress magnitudes were found in cervical regions. By comparing fringe orders between teeth the major stress magnitudes were found to be in the central incisors. Cervical regions and central incisors may therefore be more prone to resorption given their greater stresses.

Avaliação dos fatores determinantes da estética do perfil facial / Evaluation of the determinants of facial profile aesthetics

OBJETIVO: avaliar a influência da idade, do sexo, da relação oclusal sagital, do Padrão Facial e de 8 medidas do perfil facial sobre a estética do perfil. MÉTODOS: foram utilizadas tabelas de contingência, o Teste Qui-quadrado e o coeficiente de Cramér para avaliar a possível associação entre a nota dada por 32 avaliadores (14 ortodontistas, 12 leigos e 6 artistas) para a estética do perfil de 100 brasileiros - adultos, leucodermas, portadores de selamento labial passivo - e a idade, o sexo, a relação oclusal sagital, o Padrão Facial e as variáveis da análise facial numérica do perfil. RESULTADOS: não foi observada associação entre a idade, o sexo e a relação oclusal sagital e a estética do perfil facial. A associação foi observada entre a nota recebida para a estética do perfil e o Padrão Facial, o ângulo de convexidade facial e o ângulo do terço inferior da face. CONCLUSÃO: o Padrão Facial, definido na avaliação do perfil pela convexidade do perfil facial, e a projeção anterior do mento foram, entre os fatores avaliados, os determinantes para a estética do perfil facial.

OBJECTIVE: To evaluate the influence of age, gender, sagittal occlusal relationship, facial pattern and 8 facial profile measures on profile aesthetics. METHODS: Contingency tables, chi-square test and Cramer's coefficient were used to evaluate the possible association between the scores assigned by 32 examiners (14 orthodontists, 12 laypeople and 6 artists) to the aesthetics of the profile of 100 Brazilian Caucasian adults, all patients with lip seal competence, and age, gender, sagittal occlusal relationship, facial pattern and the variables of the numerical analysis of the facial profile. RESULTS: No association was found between age, gender and sagittal occlusal relationship and the aesthetics of facial profile. An association was observed between profile scores and facial pattern, facial convexity angle and lower face angle. CONCLUSIONS: Among the factors evaluated in this study, facial profile convexity and anterior chin projection were the key determinants of facial profile aesthetics.

Association between overbite and craniofacial growth pattern

The purpose of the present study was to assess the association between overbite and craniofacial growth pattern. The sample comprised eighty-six cephalograms obtained during the orthodontic pretreatment phase and analyzed using the Radiocef program to identify the craniofacial landmarks and perform orthodontic measurements. The variables utilized were overbite, the Jarabak percentage and the Vert index, as well as classifications resulting from the interpretation of these measurements. In all the statistical tests, a significance level of 5 percent was considered. Measurement reliability was checked by calculating method error. Weighted Kappa analysis showed that agreement between the facial types defined by the Vert index and the direction of growth trend established by the Jarabak percentage was not satisfactory. Owing to this lack of equivalency, a potential association between overbite and craniofacial growth pattern was evaluated using the chi-square test, considering the two methods separately. No relationship of dependence between overbite and craniofacial growth pattern was revealed by the results obtained. Therefore, it can be concluded that the classification of facial growth pattern will not be the same when considering the Jarabak and the Ricketts anayses, and that increased overbite cannot be associated with a braquifacial growth pattern, nor can openbite be associated with a dolichofacial growth pattern.

Análise fotoelástica da distribuição de tensões geradas pela mecânica de verticalização nos segundos molares inferiores / Photoelastic analysis of stress distribution in lower second molars caused by uprighting mechanic

A verticalização de molares inferiores é indicada quando ocorre inclinação mesial dos segundos molares atribuída à ausência do primeiro molar. Existem inúmeras metodologias para realização de tal movimento. O objetivo do estudo foi analisar e comparar in vitro, por meio de fotoelasticidade a distribuição de tensões nos segundos molares inferiores geradas por diferentes métodos de verticalização com aplicação de diferentes cargas. Foi avaliado um modelo confeccionado em resina flexível com a mecânica de cantiléver. Foram utilizadas forças de 50 gf, 100 gf, 150 gf, 200 gf, 250 gf e 300 gf. As regiões do segundo molar selecionadas para avaliação foram: mesial da raiz cervical, apical da raiz mesial, cervical da raiz distal e apical da raiz distal. A resultante das forças aplicadas foi aferida por meio da quantificação das franjas isocromáticas. Os valores de franjas foram descritos com uso de média e desvio padrão e verificada a concordância/reprodutibilidade entre as avaliações com uso do coeficiente de correlação intraclasse com os respectivos intervalos com 95% de confiança e calculadas as medidas de repetibilidade. Utilizando-se o cantiléver, as maiores tensões localizaram-se na região cervical mesial, seguidas de apical da raiz mesial e região cervical distal. Não foram detectadas tensões na apical da raiz distal. A aplicação de forças acima de 100 gf apresentou grandes áreas de tensões nas regiões cervical e apical da raiz mesial.

Lower molars uprighting is indicated when mesial inclination of second molars occurs due to lack of first molars. There are many methodologies to perform such movement. The aim of this study was to analyze and compare in vitro, by means of photoelasticity, the stress distribution in lower second molars generated by different uprighting methods, with application of diferrent loads. It was assessed one model manufactured with flexible resin with cantilever mechanics. The loads used were 50gf, 100gf, 150gf, 200gf, 250gf, 300gf. The second molar areas selected for the assessment were the mesial of the cervical root, apical of the mesial root, cervical of the distal root and apical of the distal root. The resultant of forces applied was measured by quantifying isochromatic fringes. The fringe values were described using the mean and the standard deviation values and the agreement/reproducibility among the assessments were verified applying the intraclass correlation coefficient in the respective intervals with 95% confidence. Repeatability measures were calculated. Using cantilever, the highest strains were found in the mesial-cervical area, followed by the apical area of the mesial root and the distal-cervical area. In the apical area of the distal root strain was not found. The application of forces above 100gf showed large areas of tension in the cervical and apical regions of the mesial root.

Forces in stainless steel, TiMolium® and TMA® intrusion arches, with different bending magnitudes

The present study compared forces in stainless steel, TiMolium® and TMA®, V-bend intrusion arches with different magnitudes of flexion. The sample consisted of rectangular-section wires, caliber .017" x .025", with ten arches of each alloy. All V-bends were made 48 mm from the midline, using the same phantom upper jaw, maintaining the same distance between the tubes fixed to the molars and the midline. Loads necessary to deflect the arches by 5, 10, 15 and 20 mm were measured by means of an Instron dynamometer with a 1 kgf load cell. Calculations for sample size confirmed the suitability of using 10 arches of each alloy. Variance tests (ANOVA) of one factor and three levels, complemented by the Tukey test for multiple comparisons, identified that TMA® intrusion arches required a smaller quantity of load in relation to conventional steel and TiMolium® at all levels of flexion. Furthermore, TiMolium® presented intermediary characteristics between steel and TMA®, and in all alloys increase in distance entailed a significant increase in force between all registered values, and that the increase in load necessary to deflect the arches at the intervals tended to decrease from first to last interval, these differences being more significant in steel, less in TiMolium® and practically non-existent in TMA®.

O presente estudo comparou as forças em arcos de intrusão com dobra V confeccionados em aço inoxidável, TiMolium® e TMA®, com diferentes magnitudes de deflexão. A amostra constou de fios de secção retangular e calibre 0,017" x 0,025", com dez arcos de cada liga. Todas as dobras em V foram confeccionadas a 48 mm distantes da linha média, e foi utilizado o mesmo manequim de maxila para manter a mesma distância entre os tubos fixados nos molares e a linha média. As cargas necessárias para defletir os arcos em 5, 10, 15 e 20 mm foram mensuradas por meio de dinamômetro com célula de carga de 1 kgf, da marca Instron. O cálculo para o tamanho de amostra confirmou a possibilidade de se utilizar dez arcos de cada liga. Os testes de variância (ANOVA) de um fator e três níveis, complementados com os testes de Tukey para comparações múltiplas, identificaram que os arcos de intrusão de TMA® requereram menor quantidade de carga em relação ao aço convencional e ao TiMolium® em todos os níveis de deflexão; que o TiMolium® apresentou características intermediárias entre o aço e o TMA®; que em todas as ligas o aumento das distâncias implicou em aumento significativo da força entre todos os valores registrados; e que os incrementos de carga necessários para defletir os arcos nos intervalos tenderam a decrescer do primeiro ao último intervalo, sendo essas diferenças mais significantes no aço, menores no TiMolium® e praticamente inexistentes no TMA®.

Análise Facial Subjetiva / Subjective Facial Analysis

INTRODUÇÃO: a análise facial tem sido um recurso diagnóstico valorizado desde os primórdios da Ortodontia. Vários autores tentaram estabelecer referências de normalidade na direção das quais os pacientes ortodônticos deveriam ser tratados. Essa preocupação da Ortodontia está em concordância com a expectativa do paciente, cuja principal motivação para o tratamento ortodôntico é a melhora estética. Para que os objetivos do profissional possam solucionar a queixa do paciente é fundamental que o ortodontista conheça os parâmetros utilizados pela sociedade na avaliação estética. Sugerimos, por meio desse trabalho, uma nomenclatura que permita a realização da Análise Facial Subjetiva, estética e morfológica. OBJETIVO: avaliar a aplicação prática da análise. METODOLOGIA: solicitou-se a um grupo heterogêneo de avaliadores (14 ortodontistas, 12 leigos e 7 artistas) que dessem notas ao perfil facial de 100 indivíduos (50 de cada gênero) classificando-os como esteticamente desagradáveis (notas 1, 2 ou 3), esteticamente aceitáveis (notas 4, 5 ou 6) e esteticamente agradáveis (notas 7, 8 ou 9). RESULTADOS: 89 por cento dos perfis foram esteticamente aceitáveis, 8 por cento desagradáveis e 3 por cento agradáveis. Em 38,35 por cento das justificativas, o nariz foi a estrutura responsável pela estética desagradável, seguida pelo mento ("queixo") em 18,9 por cento dos relatos. CONCLUSÃO: foi possível observar, portanto, que a Análise Facial Subjetiva é mais um instrumento diagnóstico, que tem sua importância aumentada por ser o parâmetro pelo qual o paciente e as pessoas com as quais ele convive vão avaliar os resultados do tratamento.

INTRODUCTION: facial analysis has been an important diagnostic method since the beginning of Orthodontics. Many authors have tried to define references of beauty to be reached with orthodontic treatment. This preoccupation is in accordance with patient expectation with orthodontic treatment. The main motivation for them is esthetic improvement. To solve it successfully orthodontists must know witch parameters the population use for esthetic evaluation. With suggest, through this paper, the Subjective Facial Analysis, esthetic and morphologic. AIM: to evaluate the application of the analysis proposed. METHODS: it was asked a heterogeneous group (14 orthodontists, 12 laymen, 7 artists) to classify 100 photographs of facial profile as esthetically pleasant (grades 7, 8 or 9), acceptable (grades 4, 5 or 6) or unpleasant (grades 1, 2 or 3). Eigthy nine percent of the sample was esthetically acceptable, 8 percent esthetically unpleasant and 3 percent esthetically pleasant. The nose and the chin were the structures of the facial profile more frequently related by appraisers (38.35 percent and 18.9 percent respectively) as responsible for the unpleasant esthetic appearance. CONCLUSION: subjective Facial Analysis is a diagnostic tool, important because is the parameter used by patients and relatives to evaluate the results of orthodontic treatment.

Estudo comparativo do perfil facial de indivíduos Padrões I, II e III portadores de selamento labial passivo / Comparative analyses of facial profile among Patterns I, II and III faces with passive lip sealment

OBJETIVO: avaliar as características numéricas do perfil facial. METODOLOGIA: avaliou-se uma amostra de 50 indivíduos, brasileiros, adultos, leucodermas, portadores de selamento labial passivo, classificados pela avaliação morfológica do perfil em 41 por cento Padrão II e 9 por cento Padrão III. A análise facial numérica do perfil foi realizada em fotografias padronizadas. As medidas obtidas para as variáveis estudadas nos dois padrões foram comparadas entre si e com as do Padrão I por meio da Análise de variância (ANOVA) complementada pelo Teste de Tukey. RESULTADOS E CONCLUSÕES: não foram observadas diferenças estatísticas entre os Grupos Padrão I, II e III nas medidas obtidas para os ângulos nasolabial e do sulco mentolabial e a proporção entre as alturas faciais média e inferior. O ângulo interlabial foi mais obtuso no Padrão III. Esse Padrão também apresentou menor convexidade facial e menor proporção do terço inferior da face. O ângulo do terço inferior da face, que avalia a protrusão mandibular, foi mais obtuso no Padrão II.

Correlation between transverse expansion and increase in the upper arch perimeter after rapid maxillary expansion

O presente estudo avaliou a correlação entre expansão transversal e aumento no perímetro do arco dentário superior, após disjunção maxilar, em dezoito pares de modelos de gesso, obtidos antes e depois de aproximadamente cinco meses da disjunção maxilar. Os modelos foram fotocopiados e as variáveis largura intermolares, largura intercaninos, comprimento e perímetro do arco dentário superior foram mensuradas por meio de paquímetro digital. Depois de verificado o erro do método, um modelo de regressão múltipla foi desenvolvido em seqüência à identificação do melhor conjunto de variáveis. A equação resultante permitiu concluir que o aumento no perímetro do arco é dado pela adição de 0,54 vezes a alteração intercaninos e de 0,87 vezes a alteração no comprimento do arco.