Evaluation of slot height in Roth prescription orthodontic brackets.

The dimensional accuracy of orthodontic brackets slots is extremely important, since inaccuracy can affect orthodontic mechanics. The aim of this study was to investigate the slot heights of Roth prescription brackets from several commercial manufacturers. A total of 360 maxillary and mandibular incisor brackets from 6 different commercial models (Kirium Line, Ovation, Roth Light, Synthesis, Integra, and Miniature Twin) were selected and divided into 18 experimental groups containing maxillary central incisor, maxillary lateral incisor, or mandibular central incisor brackets (n = 20). Brackets were viewed under a scanning electron microscope to acquire a clear image of all slot edges, and slot heights were measured at 2 locations on each bracket to acquire mean values. Group means and standard deviations were calculated and compared with the manufacturer reference value of 0.5588 mm (0.0220 inch) plus or minus a tolerance level of 0.0100 mm (∼0.0004 inch). With the exception of Synthesis maxillary lateral incisor brackets (P = 0.230), all brackets had slot heights that were significantly smaller than 0.5588 mm (P < 0.05). The measured slot heights were 1.84% to 14.91% smaller than the reference value. Virtually all measured bracket slot heights were smaller than claimed by the manufacturers, with great variability within the same brand and indication, revealing a lack of precision in the fabrication process.

Masticatory evaluation of anterior open bite malocclusion using the colorimetric capsule method.

This pediatric study aimed to assess the masticatory function of patients with anterior open bite through a method that utilizes colorimetric capsules. The sample consisted of 106 patients aged 7-11 years, of whom 51 presented with anterior open bite (experimental group) and 55 presented with normal overbite (control group). The colorimetric capsules used in this evaluation contained basic fuchsin granules, which were used to produce a solution after they were ground during chewing. Each patient was asked to chew 1 capsule for 20 seconds. The absorbance of the obtained solutions was analyzed with a spectrophotometer. Greater masticatory efficiency is directly related to the greater light absorbance of a solution, since light absorbance increases with solution concentration. A nonparametric Wilcoxon test indicated that the solutions obtained from the control group presented significantly greater light absorbance than did those from the experimental group (P < 0.05). Therefore, children with an anterior open bite exhibited less masticatory efficiency than those with a normal overbite.

Dentoskeletal and Soft Tissue Effects in the Treatment of Class II Malocclusion with Klammt's Elastic Open Activator.

AIM: The purpose of this study was to evaluate the dentoskeletal and soft tissue effects resulting from treatment with Klammt's elastic open activator (EOA) functional orthopedic appliance in patients with Class II malocclusion characterized by mandibular deficiency. MATERIALS AND METHODS: Teleradiographs were evaluated in the lateral aspect of the initial (T1) and final (T2) orthopedic phases for 16 patients with Class II, Division 1 malocclusion. The age range was from 9 to 11.2 years, with a mean age of 9.9 years. The cephalometric points were demarcated, and cephalometric measurements were obtained by the same investigator to avoid interobserver variability. RESULTS: The EOA promoted increased lower anterior facial height (LAFH), increased effective mandibular length, clockwise rotation of the mandible, retrusion and verticalization of the upper incisors, proclination and protrusion of the lower incisors, extrusion of the upper molars, mesial movement of the lower molars and anterior projection of the lower lip. CONCLUSION: Skeletal changes characterized by an increase in mandibular length and dentoalveolar changes with an emphasis on the verticalization and retrusion of the upper incisors, proclination of the lower incisors and mesial positioning of the lower molars were key to improving the occlusal relationship and esthetic facial factors. CLINICAL SIGNIFICANCE: The EOA is well indicated in patients with Class II malocclusion due to mandibular deficiency with increased overbite, proclined upper incisors and verticalized lower incisors.

Tomographic evaluation of dentoskeletal changes due to the treatment of class II malocclusion with Forsus appliance.

PURPOSE: This study evaluated dentoalveolar skeletal changes promoted by the Forsus appliance, associated to fixed orthodontic appliance, in the correction of Class II, division 1 malocclusion, from Computed Tomography (CT). METHODS: sample consisted of 10 youngsters (7 males and 3 females), with a mean age of 13.86 years. Two Forsus® models were installed after the alignment and leveling phase of the teeth. Two tomographic images of each patient, T1 and T2 (initial and immediately after removal of Forsus® appliance) were done to perform the anatomical tracings and obtain the variables of interest. The data were described by means and standard deviations. For the comparison between the initial and final phases, the paired "t" test was used and a significance level of 5% was considered (p < 0.05). RESULTS: small skeletal changes were observed, such as posterior maxillary displacement and a slight mandibular growth. Larger dentoalveolar changes occurred as extrusion, retrusion and lingualization of upper incisors; Intrusion, protrusion and vestibularization of the lower incisors; Mesialization and extrusion of lower molars. CONCLUSION: Considering the patients evaluated in this study, Forsus® presented similar results to other mandibular propulsion appliances, with dentoalveolar effects that favored Class II correction, however, with very slight skeletal modifications.

Cephalometric evaluation of symmetric and asymmetric extraction treatment for patients with Class II subdivision malocclusions.

INTRODUCTION: The purpose of this study was to cephalometrically compare the dentoskeletal and soft-tissue changes consequent to orthodontic treatment in patients with Class II subdivision malocclusion treated with asymmetric and symmetric extractions. METHODS: The sample included 54 patients with Class II subdivision malocclusion and full complement of permanent teeth, including first molars, at the beginning of treatment. Patients in group 1 (n = 27) were treated with the asymmetric extraction of 3 premolars and had initial and final mean ages of 14.07 and 16.71 years. Patients in group 2 (n = 27) were treated with the symmetric extraction of 4 premolars and had initial and final mean ages of 13.35 and 15.75 years. Lateral cephalometric radiographs were taken at pretreatment and posttreatment. T tests were used to compare the groups at pretreatment and the treatment changes between groups. RESULTS: The results demonstrated that the asymmetric extraction group had significantly less mandibular incisor retraction, less soft-tissue retraction, and greater increases in mandibular incisor extrusion and mandibular molar asymmetry index than the symmetric extraction group. CONCLUSIONS: It was concluded that the 3-premolar asymmetric extraction protocol in Class II subdivision malocclusions produces significantly less mandibular incisor and soft-tissue retraction than the 4-premolar extraction protocol.

Longitudinal effects of rapid maxillary expansion.

OBJECTIVE: To evaluate the long-term effects of rapid maxillary expansion (RME) via banded expanders in the sagittal and vertical facial planes. MATERIALS AND METHODS: The sample consisted of 25 patients who had undergone RME (with either Haas-type or Hyrax hygienic expanders) followed by standard edgewise orthodontic therapy. This sample was compared with a group of 25 patients who had edgewise treatment only and with a control nontreatment group of 26 subjects, matched by age and gender with the patients of the other two groups. Lateral cephalograms were taken before treatment (T1), at the end of treatment (T2), and at 3 years posttreatment (T3), comprising a 5-year average time of observation. RESULTS: RME treatment, in the long-term, did not influence the sagittal position of the apical jaw bases or the facial vertical dimension. CONCLUSION: Unfavorable cephalometric changes resulting immediately after RME are temporary, and therefore concerns about using RME in patients with vertical growth patterns or an extremely convex facial profile are not substantiated.

Analysis on the precision of the dimensions of self-ligating brackets.

OBJECTIVE: The present study aimed to evaluate the precision of the torque applied by 0.022" self-ligating brackets of different brands, the precision of parallelism between the inner walls of their slots, and precision of their slot height. Eighty brackets for upper central incisors of eight trademarked models were selected: Abzil, GAC, American Orthodontics, Morelli, Orthometric, Ormco, Forestadent, and Ortho Organizers. Images of the brackets were obtained using a scanning electron microscope (SEM) and these were measured using the AutoCAD 2011 software. The tolerance parameters stated in the ISO 27020 standard were used as references. The results showed that only the Orthometric, Morelli, and Ormco groups showed results inconsistent with the ISO standard. Regarding the parallelism of the internal walls of the slots, most of the models studied had results in line with the ISO prescription, except the Morelli group. In assessing bracket slot height, only the Forestadent, GAC, American Orthodontics, and Ormco groups presented results in accordance with the ISO standard. The GAC, Forestadent, and American Orthodontics groups did not differ in relation to the three factors of the ISO 27020 standard. Great variability of results is observed in relation to all the variables.

The association between periodontal disease and seizure severity in refractory epilepsy patients.

PURPOSE: Periodontal diseases are common in most populations and affect people at all socioeconomic levels. Evidence suggests that patients with epilepsy actually have higher risks of dental disease and increased oral health needs, but the frequency and consequences of poor controlled seizures on dental and periodontal health have not been reported before. We aimed to assess the impact of seizure frequency on periodontal status and oral hygiene in a sample of epilepsy patients. METHODS: One hundred and nine consecutive patients treated for epilepsy at the outpatient clinic of our University Hospital were invited to take part in an oral examination to determine their periodontal disease status, together with a control group. In addition, seizure frequency and use of medication were documented. RESULTS: In logistic regression model, patients were significantly more susceptible to bad oral hygiene, gingivitis and periodontitis that controls (p<0.001); seizure frequency was significantly related to bad oral hygiene (p=0.010), gingivitis (p<0.001) and periodontitis (p<0.001). Tooth brushing habits and presence of caries were associated with oral health in patients group. CONCLUSION: Our study found a significant positive correlation between periodontal disease and seizure severity. Epilepsy patients need to focus more on their oral health and quality of oral hygiene.

Halogen light versus LED for bracket bonding: shear bond strength.

INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus) and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE). RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.

Otimização do procedimento de colagem de braquetes ortodônticos utilizando um recipiente fotoprotetor: passo a passo / Optimization of the bonding procedure of orthodontic brackets using a photoprotective vessel: step-by-step

A resina composta fotoativável é usualmente utilizada para o procedimento de colagem de braquetes ortodônticos. No entanto, seu uso requer cuidados antes da fotoativação, pois sua polimerização pode ocorrer precocemente por outras fontes de luz, que não a de um fotoativador dentário (e.g., luz ambiente). Foi idealizado um recipiente fotoprotetor que permite o armazenamento temporário do conjunto de pinças com os braquetes preparados com resina em sua base, evitando o processo de polimerização da resina antes do momento desejado. Objetivo: este estudo tem como objetivo apresentar uma descrição detalhada do procedimento de colagem de braquetes ortodônticos estéticos cerâmicos, quando se utiliza um recipiente fotoprotetor para otimizar o atendimento. Relato de caso: paciente do sexo feminino, 24 anos de idade, submeteu-se ao tratamento ortodôntico em clínica particular. Foram utilizados braquetes ortodônticos autoligados, cerâmicos de alumina policristalina. A colagem dos braquetes foi realizada na arcada inferior de maneira tradicional, porém se fez uso de um recipiente fotoprotetor (protótipo) para otimizar o procedimento. O recipiente teve como finalidade principal o armazenamento temporário de braquetes ortodônticos apreendidos em pinças ortodônticas, já com resina composta para colagem em suas bases. Concluiu-se a instalação do aparelho ortodôntico com a colocação de um arco ortodôntico redondo Ni-Ti 0,014". Considerações finais: a utilização do recipiente fotoprotetor mostrou-se clinicamente eficaz e apresentou um bom resultado final da satisfação tanto do profissional quanto do paciente. O seu uso foi capaz de reduzir o tempo de cadeira do paciente durante o procedimento e impediu a polimerização precoce da resina composta de colagem utilizada. (AU)

The photo-activated resin composite is usually used for the bonding procedure of orthodontic brackets. However, their use requires caution prior to photoactivation, as their polymerization may occur early by light sources other than a dental photoactivator (e.g. ambient light). A photoprotective vessel has been developed to allow temporary storage of the clamps assembly with the resin-prepared brackets, avoiding the polymerization process of the resin prior to the desired moment. Objective: this study purpose was to present a detailed description of the bonding procedure of ceramic orthodontic brackets when using a photoprotective vessel to optimize care. Case report: a 24-year-old female patient underwent orthodontic treatment in a private practice. Orthodontic brackets of polycrystalline alumina ceramics were used for treatment. Bracket bonding was performed in the lower arch in the traditional manner, however a photoprotective vessel (prototype) was used to optimize the procedure. The main purpose of the vessel was the temporary storage of orthodontic brackets- -clamps assembly, already with composite resin for bonding in their bases. The installation of the orthodontic appliance was finished with the placement of a 0.014" round Ni-Ti orthodontic arch. Final considerations: the use of the photoprotective vessel was clinically effective and with a good end result in both professional and patient satisfaction. Its use was able to reduce the patient's chair time during the procedure and prevented the early polymerization of the bonded composite resin used. (AU)

O efeito de diferentes níveis de PH em soluções de flúor a 1, 1% na corrosão de arcos NITI / The effect of different PH levels on fluoride solutions at 1. 1% on corrosion of NITI archs

Objetivo: Determinar o pH crítico para ocorrer a corrosão de arcos NiTi em soluções de flúor a 1,1%, variando o pH de 3,5 a 7,0. Materiais e Métodos: Doze amostras com 10mm de comprimento de fio superelástico NiTi 0017 x 0025 (Abzil), obtidas do segmento distal dos arcos. As amostras foram aleatoriamente separadas e imersas dentro de recipientes contendo 40ml de seis soluções (água, soluções fluoretadas com pH: 3,5; 4,0; 4,5; 5,0; 5,5; 6,0; 6,5 e 7,0), sob uma mesa agitadora durante 90 minutos. Todas as amostras foram, então, levadas ao MEV. As imagens das amostras imersas em água e soluções fluoretadas com pH 7,0, 6,5 e 6,0 não se apresentaram diferentes, no entanto a partir da solução fluoretada com pH 5,5, as imagens superficiais apresentaram características diferentes dos grupos anteriores. Conclusão: Com base nos resultados obtidos neste estudo, o pH crítico para corrosão de arcos NiTi em soluções de flúor a 1,1% parece estar entre 6,0 e 5,5

Objective: To determine the critical pH to occur corrosion of NiTi arches in 1.1% fluoride solutions by varying the pH between 3.5 and 7.0. Materials and Methods: Twelve samples of 10 mm length superelastic NiTi wire 0017 x 0025 (Abzil) obtained in the distal segment of the arcs. The samples were randomly separated and immersed in 40 ml of six solutions (water, fluoride solutions with pH: 3.5; 4.0; 4.5; 5.0; 5.5; 6.0; 6.5 and 7.0) under a shaker table for 90 minutes. All samples were observed under SEM. The images of the samples immersed in water and fluoride solutions at pH 7.0, 6.5 and 6.0 did not show differences, however from the fluoride solution at pH 5.5, the surface characteristics of images presented differences from above groups. Conclusion: Based on the results obtained in this study the critical pH for corrosion of NiTi arches in fluoride solutions to 1.1% appears to be between 6.0 and 5.5

Comparative in vitro study of the shear bond strength of brackets bonded with restorative and orthodontic resins.

The aim of this study was to evaluate the shear bond strength of brackets bonded with different restorative systems and compare it with that afforded by an established orthodontic bonding system. Seventy human bicuspids were used, divided into five different groups with 14 teeth each. Whereas a specific orthodontic bonding resin (Transbond™ XT) was used in the control group, the restorative systems Charisma, Tetric Ceram, TPH Spectrum and Z100 were used in the other four groups. Seven days after bonding the brackets to the samples, shear forces were applied under pressure in a universal testing machine. The data collected was evaluated using the ANOVA test and, when a difference was identified, the Tukey test was applied. A 5% level of significance was adopted. The mean results of the shear bond strength tests were as follows: Group 1 (Charisma), 14.98 MPa; Group 2 (Tetric Ceram), 15.16 MPa; Group 3 (TPH), 17.70 MPa; Group 4 (Z100), 13.91 MPa; and Group 5 or control group (Transbond™ XT), 17.15 MPa. No statistically significant difference was found among the groups. It was concluded that all tested resins have sufficient bond strength to be recommended for bonding orthodontic brackets.

Are torque values of preadjusted brackets precise?

OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º) presented statistically significant difference from the proposed values (-7º). For the mandibular canines, American Orthodontics (-6.34º) and Ortho Organizers (-6.25º) presented statistically significant differences from the standards (-6º). Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.

Metallographic analysis of the internal microstructure of orthodontic mini-implants.

Effective orthodontic anchorage may be obtained by miniimplants inserted into the maxillary bones. However, the risk of miniimplant failure is one of the most important issues, especially the rupture of its structure referred to as fracture, mainly due to metal deficiencies. This study analyzed the internal microstructure of orthodontic mini-implants, ascertaining the composition of the metal to detect possible discontinuities from the surface to the core of the screws. Eighteen samples of mini-implants, of 3 different brands, were obtained. The samples were cold-embedded in methyl methacrylate polymer, and were sectioned both longitudinally (3 samples of each brand) and transversely (the other 3 screws of each brand). After preparation, the samples were observed using a light microscope at up to 2,000 x magnification. The results showed that the mini-implants thus analyzed were composed of an Alpha-Beta globular phase of titanium alloy, patterns A1 and A9 (in accordance with the "Technical Committee of European Titanium Producers"). The miniimplants did not present any defects such as bubbles, imperfections or fissures, in either longitudinal or transverse sections, in their internal microstructure. All samples met the requirements of international norms. Orthodontists must be aware of the metal composition and internal microstructure of mini-implants, to decrease the risk of fractures.

Prevalência de dentes supranumerários em pacientes de Ortodontia / Supernumerary teeth prevalence in Orthodontic patients

Existem várias alterações nos arcos dentários, entre estas se encontram as de número, forma e tamanho dos dentes. O dente supranumerário representa um fator etiológico importante e frequente da má oclusão. Este trabalho teve o objetivo de avaliar a prevalência de dentes supranumerários nos pacientes tratados nos cursos de pós-graduação em Ortodontia da Universidade Cidade de São Paulo. A amostra, composta por 1117 radiografias panorâmicas de pacientes que se submeteram a tratamento ortodôntico corretivo, foi estudada quanto à distribuição da prevalência de dentes supranumerários entre os gêneros, os arcos dentários e as regiões bucais. A média de idade da amostra foi de 13,7 anos, sendo que 56% dos pacientes eram do gênero feminino e 44% do masculino. Do total analisada, apenas 18 pacientes (1,61%) apresentaram dentes supranumerários. Em relação ao gênero, verificou-se uma prevalência de 1,9% no gênero feminino, enquanto o gênero masculino apresentou prevalência de 1,2%. Na comparação entre os gêneros não se verificou diferença com significância estatística. No total foram constatados 24 dentes supranumerários, uma vez que existiram radiografias de pessoas com a presença de mais de um dente supranumerário. Destes 24 dentes, 16 estavam no arco superior e 8 no arco inferior. A partir da metodologia aplicada e dos resultados obtidos, pôde-se concluir que: a prevalência de dentes supranumerários foi de 1,61% dos indivíduos da amostra; não se pôde verificar diferença significante na prevalência de supranumerários entre os gêneros masculino e feminino; e a prevalência de dentes supranumerários foi estatisticamente semelhante para os arcos dentários superior e inferior, apesar de 66,7% deles terem sido localizados no arco superior

There are several tooth abnormalities in the dental arches, which can be in the number, shape or size of the teeth. The supernumerary teeth represent an important etiologic factor of malocclusion, quietly frequent. This study aimed to evaluate the prevalence of supernumerary teeth in the patients who has been orthodontic treated in the Graduation course of University of São Paulo City (UNICID). The sample, which consisted of 1117 panoramic radiographs of patients who have undergone orthodontic treatment, was studied on the distribution of the prevalence of supernumerary teeth gender, dental arches and mouth regions. The average age of the sample was 13.7 years, and 56% of patients were female and 44% male. Of the total analyzed, only 18 patients (1.61%) had supernumerary teeth. Regarding to gender, there was a prevalence of 1.9% among females, while males showed prevalence of 1.2%. In comparing genders, there was no statistically significant difference. A total of 24 supernumerary teeth were observed, once existed radiographs from people with more than one supernumerary tooth. Considering these 24 supernumerary teeth, 16 were located in the upper arch, while just 8 were in the lower arch. From the applied methodology and the results obtained, it could be concluded that: the prevalence of supernumerary teeth was 1.61% of individuals in the sample; There was not found significant differences in the prevalence of supernumerary between males and females; and prevalence of supernumerary teeth was statistically similar to the upper and lower dental arches, although 66.7% of them being located on the upper arch

Posicionadores de braquetes ortodônticos ? revisão de literatura e desenvolvimento de um projeto de patente / Orthodontic brackets positioning ? literature review and development of a patent project

Em Ortodontia, a colagem de braquetes é um dos passos mais importantes durante o tratamento, principalmente na técnica Straight Wire, na qual os acessórios possuem uma forma específica para levar cada dente à posição prescrita, no que se refere à inclinação, angulação, ou mesmo adequando a posição vestíbulo-lingual das coroas, que variam devido às suas diferentes espessuras anatômicas. Outro ponto fundamental é a altura na qual os braquetes são posicionados, o que interfere diretamente na oclusão e na estética do sorriso. Se ocorre o posicionamento incorreto dos braquetes, além de contatos prematuros e outros possíveis danos, o profissional despenderá mais tempo realizando dobras compensatórias ou recolagens de acessórios. Assim sendo, o objetivo deste trabalho foi desenvolver e inscrever um projeto de patente, composto por um conjunto de posicionadores de braquetes ortodônticos, no intuito de promover um melhor e mais fácil posicionamento dos braquetes durante a colagem, diminuindo a chance de erros, otimizando o processo e tornando a rotina daclínica ortodôntica mais previsível e eficiente

In Orthodontics, brackets bonding is one of the most important steps during the treatment, especially in Straight Wire technique, in which accessories have an specific shape to led each tooth to its correct position, considering inclination, angulation, or even the buccal-lingual crowns position, that varies according to its thickness. Another important point is the height of the brackets, what interferes directly in the occlusion and in smile aesthetics. When an incorrect positioning of the brackets occurs, the clinician wastes time with rebonding or making wire bends. The aim of this study was to develop and submit a patent project, composed by a kit of brackets positioners, to promote a better and easier positioning during bonding, decreasing the chances of errors, optimizing the process and improving the orthodontic routine, with more predictability and efficiency

The importance of the facial profile in orthodontic diagnosis and treatment planning: a patient report.

Orthodontic treatment to improve not only tooth alignment but also facial esthetics is a given in modern society. This paper illustrates this assumption with a report of a patient with a Class I, maxillary retrusion, concave profile, and retrusion of the upper and lower lips. Maxillary expansion was followed by face mask therapy and orthodontic treatment, which significantly improved the soft tissue profile by projecting the upper lip.

Halogen light versus LED for bracket bonding: shear bond strength

INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus) and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE). RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.

INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus) e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe). RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado um protocolo de aplicação da luz com tempo de ativação de 40 segundos.

Effects of masticatory hypofunction on mandibular morphology, mineral density and basal bone area

AIM: This experimental study investigated the association between masticatory hypofunction and mandibular morphological dimensions and internal bone characteristics. METHODS: Twentyfour 21-day-old male Wistar rats were randomly divided into two groups, according to the diet consistency. The control group (CG) was fed a solid diet (pellets) and the experimental group (EG) received a powdered diet during 50 days. All animals were euthanized and their mandibles removed and processed for histomorphometric analysis. A calibrated examiner performed linear and angular measurements (mandibular body length and height, mandibular lengths, ramus depth and height, mandibular base depth, mandibular head and gonial angle) on photographs, estimated bone density in the mandibular ramus region on digital radiographs and assessed the area of cortical and trabecular bone tissue in the second molar region, in 5-µm-thick serial cuts stained with Cason's Trichrome. Measurements for the study groups were compared using Mann-Whitney test (α=0.05). larvae to induce experimental candidiasis, and after 24 hours, the survival rate was assessed. RESULTS: some of the macroscopic dimensions evaluated on photographs were significantly smaller in EG compared to CG, specifically mandibular ramus height (10.77 mm vs. 11.11 mm, p=0.0375), mandibular body length (21.67 mm vs. 22.36 mm, p=0.0165) and height (4.24 mm vs. 4.54 mm, p=0.0016), as well as mandibular base depth (1.24 mm vs. 1.47 mm, p=0.0325). The relative mineral bone density was significantly decreased in EG (1.04) compared to CG (1.25), p<0.001. Rats in the EG also presented smaller trabecular and cortical bone area (2.36 mm²) than those in CG (3.16 mm²), p<0.001. CONCLUSIONS: Based on the above-mentioned measurements, it may be concluded that masticatory hypofunction induced by a powdered diet affected mandibular morphology and was associated with significantly reduced bone content.